Commit Graph

19181 Commits

Author SHA1 Message Date
Vincent Sanders 75c349062a ARM: 8153/1: Enable gcov support on the ARM architecture
Enable gcov support for ARM based on original patches by David
Singleton and George G. Davis

Riku - updated to patch to current mainline kernel. The patch
has been submitted in 2010, 2012 - for symmetry, now in 2014 too.

https://lwn.net/Articles/390419/
http://marc.info/?l=linux-arm-kernel&m=133823081813044

v2: remove arch/arm/kernel from gcov disabled files

Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Vincent Sanders <vincent.sanders@collabora.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-09-26 14:39:57 +01:00
Guenter Roeck b63adb9795 kernel: add support for kernel restart handler call chain
Various drivers implement architecture and/or device specific means to
restart (reset) the system.  Various mechanisms have been implemented to
support those schemes.  The best known mechanism is arm_pm_restart, which
is a function pointer to be set either from platform specific code or from
drivers.  Another mechanism is to use hardware watchdogs to issue a reset;
this mechanism is used if there is no other method available to reset a
board or system.  Two examples are alim7101_wdt, which currently uses the
reboot notifier to trigger a reset, and moxart_wdt, which registers the
arm_pm_restart function.

The existing mechanisms have a number of drawbacks.  Typically only one
scheme to restart the system is supported (at least if arm_pm_restart is
used).  At least in theory there can be multiple means to restart the
system, some of which may be less desirable (for example one mechanism may
only reset the CPU, while another may reset the entire system).  Using
arm_pm_restart can also be racy if the function pointer is set from a
driver, as the driver may be in the process of being unloaded when
arm_pm_restart is called.  Using the reboot notifier is always racy, as it
is unknown if and when other functions using the reboot notifier have
completed execution by the time the watchdog fires.

Introduce a system restart handler call chain to solve the described
problems.  This call chain is expected to be executed from the
architecture specific machine_restart() function.  Drivers providing
system restart functionality (such as the watchdog drivers mentioned
above) are expected to register with this call chain.  By using the
priority field in the notifier block, callers can control restart handler
execution sequence and thus ensure that the restart handler with the
optimal restart capabilities for a given system is called first.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jonas Jensen <jonas.jensen@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2014-09-26 00:00:06 -07:00
Zefan Li e756c7b698 Revert "cgroup: remove redundant variable in cgroup_mount()"
This reverts commit 0c7bf3e8ca.

If there are child cgroups in the cgroupfs and then we umount it,
the superblock will be destroyed but the cgroup_root will be kept
around. When we mount it again, cgroup_mount() will find this
cgroup_root and allocate a new sb for it.

So with this commit we will be trapped in a dead loop in the case
described above, because kernfs_pin_sb() keeps returning NULL.

Currently I don't see how we can avoid using both pinned_sb and
new_sb, so just revert it.

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Reported-by: Andrey Wagin <avagin@gmail.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-26 00:16:23 -04:00
Linus Torvalds f4cb707e7a ACPI and power management fixes for 3.17-rc7
- Revert of a recent hibernation core commit that introduced
    a NULL pointer dereference during resume for at least one user
    (Rafael J Wysocki).
 
  - Fix for the ACPI LPSS (Low-Power Subsystem) driver to disable
    asynchronous PM callback execution for LPSS devices during system
    suspend/resume (introduced in 3.16) which turns out to break
    ordering expectations on some systems.  From Fu Zhonghui.
 
  - cpufreq core fix related to the handling of sysfs nodes during
    system suspend/resume that has been broken for intel_pstate
    since 3.15 from Lan Tianyu.
 
  - Restore the generation of "online" uevents for ACPI container
    devices that was removed in 3.14, but some user space utilities
    turn out to need them (Rafael J Wysocki).
 
  - The cpufreq core fails to release a lock in an error code path
    after changes made in 3.14.  Fix from Prarit Bhargava.
 
  - ACPICA and ACPI/GPIO fixes to make the handling of ACPI GPIO
    operation regions (which means AML using GPIOs) work correctly
    in all cases from Bob Moore and Srinivas Pandruvada.
 
  - Fix for a wrong sign of the ACPI core's create_modalias() return
    value in case of an error from Mika Westerberg.
 
  - ACPI backlight blacklist entry for ThinkPad X201s from Aaron Lu.
 
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Merge tag 'pm+acpi-3.17-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI and power management fixes from Rafael Wysocki:
 "These are regression fixes (ACPI hotplug, cpufreq, hibernation, ACPI
  LPSS driver), fixes for stuff that never worked correctly (ACPI GPIO
  support in some cases and a wrong sign of an error code in the ACPI
  core in one place), and one blacklist item for ACPI backlight
  handling.

  Specifics:

   - Revert of a recent hibernation core commit that introduced a NULL
     pointer dereference during resume for at least one user (Rafael J
     Wysocki).

   - Fix for the ACPI LPSS (Low-Power Subsystem) driver to disable
     asynchronous PM callback execution for LPSS devices during system
     suspend/resume (introduced in 3.16) which turns out to break
     ordering expectations on some systems.  From Fu Zhonghui.

   - cpufreq core fix related to the handling of sysfs nodes during
     system suspend/resume that has been broken for intel_pstate since
     3.15 from Lan Tianyu.

   - Restore the generation of "online" uevents for ACPI container
     devices that was removed in 3.14, but some user space utilities
     turn out to need them (Rafael J Wysocki).

   - The cpufreq core fails to release a lock in an error code path
     after changes made in 3.14.  Fix from Prarit Bhargava.

   - ACPICA and ACPI/GPIO fixes to make the handling of ACPI GPIO
     operation regions (which means AML using GPIOs) work correctly in
     all cases from Bob Moore and Srinivas Pandruvada.

   - Fix for a wrong sign of the ACPI core's create_modalias() return
     value in case of an error from Mika Westerberg.

   - ACPI backlight blacklist entry for ThinkPad X201s from Aaron Lu"

* tag 'pm+acpi-3.17-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Revert "PM / Hibernate: Iterate over set bits instead of PFNs in swsusp_free()"
  gpio / ACPI: Use pin index and bit length
  ACPICA: Update to GPIO region handler interface.
  ACPI / platform / LPSS: disable async suspend/resume of LPSS devices
  cpufreq: release policy->rwsem on error
  cpufreq: fix cpufreq suspend/resume for intel_pstate
  ACPI / scan: Correct error return value of create_modalias()
  ACPI / video: disable native backlight for ThinkPad X201s
  ACPI / hotplug: Generate online uevents for ACPI containers
2014-09-25 15:25:52 -07:00
NeilBrown cbbce82209 SCHED: add some "wait..on_bit...timeout()" interfaces.
In commit c1221321b7
   sched: Allow wait_on_bit_action() functions to support a timeout

I suggested that a "wait_on_bit_timeout()" interface would not meet my
need.  This isn't true - I was just over-engineering.

Including a 'private' field in wait_bit_key instead of a focused
"timeout" field was just premature generalization.  If some other
use is ever found, it can be generalized or added later.

So this patch renames "private" to "timeout" with a meaning "stop
waiting when "jiffies" reaches or passes "timeout",
and adds two of the many possible wait..bit..timeout() interfaces:

wait_on_page_bit_killable_timeout(), which is the one I want to use,
and out_of_line_wait_on_bit_timeout() which is a reasonably general
example.  Others can be added as needed.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
2014-09-25 08:23:57 -04:00
Zefan Li 2ad654bc5e cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags
When we change cpuset.memory_spread_{page,slab}, cpuset will flip
PF_SPREAD_{PAGE,SLAB} bit of tsk->flags for each task in that cpuset.
This should be done using atomic bitops, but currently we don't,
which is broken.

Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happened
when one thread tried to clear PF_USED_MATH while at the same time another
thread tried to flip PF_SPREAD_PAGE/PF_SPREAD_SLAB. They both operate on
the same task.

Here's the full report:
https://lkml.org/lkml/2014/9/19/230

To fix this, we make PF_SPREAD_PAGE and PF_SPREAD_SLAB atomic flags.

v4:
- updated mm/slab.c. (Fengguang Wu)
- updated Documentation.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>
Fixes: 950592f7b9 ("cpusets: update tasks' page/slab spread flags in time")
Cc: <stable@vger.kernel.org> # 2.6.31+
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-24 22:16:06 -04:00
Tomeu Vizoso 7990da71eb PM / QoS: Add PM_QOS_MEMORY_BANDWIDTH class
Also adds a class type PM_QOS_SUM that aggregates the values by summing them.

It can be used by memory controllers to calculate the optimum clock frequency
based on the bandwidth needs of the different memory clients.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-25 01:18:33 +02:00
Rafael J. Wysocki 5c4dd348af Revert "PM / Hibernate: Iterate over set bits instead of PFNs in swsusp_free()"
Revert commit 6efde38f07 (PM / Hibernate: Iterate over set bits
instead of PFNs in swsusp_free()) that introduced a NULL pointer
dereference during system resume from hibernation:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff810a8cc1>] swsusp_free+0x21/0x190
PGD b39c2067 PUD b39c1067 PMD 0
Oops: 0000 [#1] SMP
Modules linked in: <irrelevant list of modules>
CPU: 1 PID: 4898 Comm: s2disk Tainted: G         C     3.17-rc5-amd64 #1 Debian 3.17~rc5-1~exp1
Hardware name: LENOVO 2776LEG/2776LEG, BIOS 6EET55WW (3.15 ) 12/19/2011
task: ffff88023155ea40 ti: ffff8800b3b14000 task.ti: ffff8800b3b14000
RIP: 0010:[<ffffffff810a8cc1>]  [<ffffffff810a8cc1>]
swsusp_free+0x21/0x190
RSP: 0018:ffff8800b3b17ea8  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8800b39bab00 RCX: 0000000000000001
RDX: ffff8800b39bab10 RSI: ffff8800b39bab00 RDI: 0000000000000000
RBP: 0000000000000010 R08: 0000000000000000 R09: 0000000000000000
R10: ffff8800b39bab10 R11: 0000000000000246 R12: ffffea0000000000
R13: ffff880232f485a0 R14: ffff88023ac27cd8 R15: ffff880232927590
FS:  00007f406d83b700(0000) GS:ffff88023bc80000(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 00000000b3a62000 CR4: 00000000000007e0
Stack:
 ffff8800b39bab00 0000000000000010 ffff880232927590 ffffffff810acb4a
 ffff8800b39bab00 ffffffff811a955a ffff8800b39bab10 0000000000000000
 ffff88023155f098 ffffffff81a6b8c0 ffff88023155ea40 0000000000000007
Call Trace:
 [<ffffffff810acb4a>] ? snapshot_release+0x2a/0xb0
 [<ffffffff811a955a>] ? __fput+0xca/0x1d0
 [<ffffffff81080627>] ? task_work_run+0x97/0xd0
 [<ffffffff81012d89>] ? do_notify_resume+0x69/0xa0
 [<ffffffff8151452a>] ? int_signal+0x12/0x17
Code: 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 41 54 48 8b 05 ba 62 9c 00 49 bc 00 00 00 00 00 ea ff ff 48 8b 3d a1 62 9c 00 55 53 <48> 8b 10 48 89 50 18 48 8b 52 20 48 c7 40 28 00 00 00 00 c7 40
RIP  [<ffffffff810a8cc1>] swsusp_free+0x21/0x190
 RSP <ffff8800b3b17ea8>
CR2: 0000000000000000
---[ end trace f02be86a1ec0cccb ]---

due to forbidden_pages_map being NULL in swsusp_free().

Fixes: 6efde38f07 "PM / Hibernate: Iterate over set bits instead of PFNs in swsusp_free()"
Reported-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-25 00:59:54 +02:00
David S. Miller 4daaab4f0c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-09-24 16:48:32 -04:00
Tejun Heo 2aad2a86f6 percpu_ref: add PERCPU_REF_INIT_* flags
With the recent addition of percpu_ref_reinit(), percpu_ref now can be
used as a persistent switch which can be turned on and off repeatedly
where turning off maps to killing the ref and waiting for it to drain;
however, there currently isn't a way to initialize a percpu_ref in its
off (killed and drained) state, which can be inconvenient for certain
persistent switch use cases.

Similarly, percpu_ref_switch_to_atomic/percpu() allow dynamic
selection of operation mode; however, currently a newly initialized
percpu_ref is always in percpu mode making it impossible to avoid the
latency overhead of switching to atomic mode.

This patch adds @flags to percpu_ref_init() and implements the
following flags.

* PERCPU_REF_INIT_ATOMIC	: start ref in atomic mode
* PERCPU_REF_INIT_DEAD		: start ref killed and drained

These flags should be able to serve the above two use cases.

v2: target_core_tpg.c conversion was missing.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-09-24 13:31:50 -04:00
Tejun Heo d06efebf0c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block into for-3.18
This is to receive 0a30288da1 ("blk-mq, percpu_ref: implement a
kludge for SCSI blk-mq stall during probe") which implements
__percpu_ref_kill_expedited() to work around SCSI blk-mq stall.  The
commit reverted and patches to implement proper fix will be added.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
2014-09-24 13:00:21 -04:00
Jiri Olsa 802c8a61d4 Revert "perf: Do not allow optimized switch for non-cloned events"
This reverts commit 1f9a7268c6.

With the fix of the initial state for the cloned event we now correctly
handle the error described in:

  1f9a7268c6 perf: Do not allow optimized switch for non-cloned events

so we can revert it.

I made an automated test for this, but its not suitable for automated
perf tests framework. It needs to be customized for each machine (the
more cpu the higher numbers for GROUPS/WORKERS/BYTES) and it could take
longer time to hit the issue.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140910143535.GD2409@krava.brq.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:48:13 +02:00
Jiri Olsa 1929def9e6 perf: Fix child event initial state setup
Currently we initialize the child event based on the original
parent state. This is wrong, because the original parent event
(and its state) is not related to current fork and also could
be already gone.

We need to initialize the child state based on the immediate
parent event state.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1410520708-19275-2-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:48:12 +02:00
Jiri Olsa dc633982ff perf: Do not POLLHUP event if it has children
Currently we return POLLHUP in event polling if the monitored
process is done, but we didn't consider possible children,
that might be still running and producing data.

Before returning POLLHUP making sure that:

   1) the monitored task has exited and that
   2) we don't have any children to monitor

Also adding parent wakeup when the child event is gone.

Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410520708-19275-1-git-send-email-jolsa@kernel.org
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:48:11 +02:00
Kirill Tkhai 8aa6f0ebf4 sched/rt: Use resched_curr() in task_tick_rt()
Some time ago PREEMPT_NEED_RESCHED was implemented,
so reschedule technics is a little more difficult now.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140922183642.11015.66039.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:12 +02:00
Kirill Tkhai f1e3a0932f sched: Use rq->rd in sched_setaffinity() under RCU read lock
Probability of use-after-free isn't zero in this place.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # v3.14+
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140922183636.11015.83611.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:11 +02:00
Kirill Tkhai 16303ab2fe sched: cleanup: Rename 'out_unlock' to 'out_free_new_mask'
Nothing is locked there, so label's name only confuses a reader.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140922183630.11015.59500.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:10 +02:00
Kirill Tkhai 66339c31bc sched: Use dl_bw_of() under RCU read lock
dl_bw_of() dereferences rq->rd which has to have RCU read lock held.
Probability of use-after-free isn't zero here.

Also add lockdep assert into dl_bw_cpus().

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # v3.14+
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140922183624.11015.71558.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:09 +02:00
Kirill Tkhai 7a96c231ca sched/fair: Remove duplicate code from can_migrate_task()
Combine two branches which do the same.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140922183612.11015.64200.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:07 +02:00
Peter Zijlstra c55f5158f5 sched, mips, ia64: Remove __ARCH_WANT_UNLOCKED_CTXSW
Kirill found that there's a subtle race in the
__ARCH_WANT_UNLOCKED_CTXSW code, and instead of fixing it, remove the
entire exception because neither arch that uses it seems to actually
still require it.

Boot tested on mips64el (qemu) only.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kirill Tkhai <tkhai@yandex.ru>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: oleg@redhat.com
Cc: linux@roeck-us.net
Cc: linux-ia64@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Link: http://lkml.kernel.org/r/20140923150641.GH3312@worktop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:05 +02:00
Oleg Nesterov 5bd96ab6fe sched: print_rq(): Don't use tasklist_lock
read_lock_irqsave(tasklist_lock) in print_rq() looks strange. We do
not need to disable irqs, and they are already disabled by the caller.

And afaics this lock buys nothing, we can rely on rcu_read_lock().
In this case it makes sense to also move rcu_read_lock/unlock from
the caller to print_rq().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140921193341.GA28628@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:04 +02:00
Oleg Nesterov 3472eaa1f1 sched: normalize_rt_tasks(): Don't use _irqsave for tasklist_lock, use task_rq_lock()
1. read_lock(tasklist_lock) does not need to disable irqs.

2. ->mm != NULL is a common mistake, use PF_KTHREAD.

3. The second ->mm check can be simply removed.

4. task_rq_lock() looks better than raw_spin_lock(&p->pi_lock) +
   __task_rq_lock().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140921193338.GA28621@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:03 +02:00
Oleg Nesterov 8651c65844 sched: Fix the task-group check in tg_has_rt_tasks()
tg_has_rt_tasks() wants to find an RT task in this task_group, but
task_rq(p)->rt.tg wrongly checks the root rt_rq.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Link: http://lkml.kernel.org/r/20140921193336.GA28618@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:47:00 +02:00
Nicolas Pitre 83a0a96a5f sched/fair: Leverage the idle state info when choosing the "idlest" cpu
The code in find_idlest_cpu() looks for the CPU with the smallest load.
However, if multiple CPUs are idle, the first idle CPU is selected
irrespective of the depth of its idle state.

Among the idle CPUs we should pick the one with with the shallowest idle
state, or the latest to have gone idle if all idle CPUs are in the same
state.  The later applies even when cpuidle is configured out.

This patch doesn't cover the following issues:

- The idle exit latency of a CPU might be larger than the time needed
  to migrate the waking task to an already running CPU with sufficient
  capacity, and therefore performance would benefit from task packing
  in such case (in most cases task packing is about power saving).

- Some idle states have a non negligible and non abortable entry latency
  which needs to run to completion before the exit latency can start.
  A concurrent patch series is making this info available to the cpuidle
  core.  Once available, the entry latency with the idle timestamp could
  determine when the exit latency may be effective.

Those issues will be handled in due course.  In the mean time, what
is implemented here should improve things already compared to the current
state of affairs.

Based on an initial patch from Daniel Lezcano.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-pm@vger.kernel.org
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/n/tip-@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:46:59 +02:00
Daniel Lezcano 442bf3aaf5 sched: Let the scheduler see CPU idle states
When the cpu enters idle, it stores the cpuidle state pointer in its
struct rq instance which in turn could be used to make a better decision
when balancing tasks.

As soon as the cpu exits its idle state, the struct rq reference is
cleared.

There are a couple of situations where the idle state pointer could be changed
while it is being consulted:

1. For x86/acpi with dynamic c-states, when a laptop switches from battery
   to AC that could result on removing the deeper idle state. The acpi driver
   triggers:
	'acpi_processor_cst_has_changed'
		'cpuidle_pause_and_lock'
			'cpuidle_uninstall_idle_handler'
				'kick_all_cpus_sync'.

All cpus will exit their idle state and the pointed object will be set to
NULL.

2. The cpuidle driver is unloaded. Logically that could happen but not
in practice because the drivers are always compiled in and 95% of them are
not coded to unregister themselves.  In any case, the unloading code must
call 'cpuidle_unregister_device', that calls 'cpuidle_pause_and_lock'
leading to 'kick_all_cpus_sync' as mentioned above.

A race can happen if we use the pointer and then one of these two scenarios
occurs at the same moment.

In order to be safe, the idle state pointer stored in the rq must be
used inside a rcu_read_lock section where we are protected with the
'rcu_barrier' in the 'cpuidle_uninstall_idle_handler' function. The
idle_get_state() and idle_put_state() accessors should be used to that
effect.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Cc: linaro-kernel@lists.linaro.org
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:46:58 +02:00
Juri Lelli 91ec6778ec sched/deadline: Fix inter- exclusive cpusets migrations
Users can perform clustered scheduling using the cpuset facility.
After an exclusive cpuset is created, task migrations happen only
between CPUs belonging to the same cpuset. Inter- cpuset migrations
can only happen when the user requires so, moving a task between
different cpusets. This behaviour is broken in SCHED_DEADLINE, as
currently spurious inter- cpuset migration may happen without user
intervention.

This patch fix the problem (and shuffles the code a bit to improve
clarity).

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: raistlin@linux.it
Cc: michael@amarulasolutions.com
Cc: fchecconi@gmail.com
Cc: daniel.wagner@bmw-carit.de
Cc: vincent@legout.info
Cc: luca.abeni@unitn.it
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1411118561-26323-4-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:46:57 +02:00
Juri Lelli a5e7be3b28 sched/deadline: Clear dl_entity params when setscheduling to different class
When a task is using SCHED_DEADLINE and the user setschedules it to a
different class its sched_dl_entity static parameters are not cleaned
up. This causes a bug if the user sets it back to SCHED_DEADLINE with
the same parameters again.  The problem resides in the check we
perform at the very beginning of dl_overflow():

	if (new_bw == p->dl.dl_bw)
		return 0;

This condition is met in the case depicted above, so the function
returns and dl_b->total_bw is not updated (the p->dl.dl_bw is not
added to it). After this, admission control is broken.

This patch fixes the thing, properly clearing static parameters for a
task that ceases to use SCHED_DEADLINE.

Reported-by: Daniele Alessandrelli <daniele.alessandrelli@gmail.com>
Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Reported-by: Vincent Legout <vincent@legout.info>
Tested-by: Luca Abeni <luca.abeni@unitn.it>
Tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Tested-by: Vincent Legout <vincent@legout.info>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Fabio Checconi <fchecconi@gmail.com>
Cc: Dario Faggioli <raistlin@linux.it>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1411118561-26323-2-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 14:46:56 +02:00
Oleg Nesterov be34f0f3e6 sched/numa: Kill the wrong/dead TASK_DEAD check in task_numa_fault()
current->state == TASK_DEAD means that the task is doing its
last schedule(), page fault is obviously impossible at this
stage.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140921194743.GA30114@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-24 09:35:05 +02:00
Richard Guy Briggs 9eab339b19 audit: get comm using lock to avoid race in string printing
When task->comm is passed directly to audit_log_untrustedstring() without
getting a copy or using the task_lock, there is a race that could happen that
would output a NULL (\0) in the output string that would effectively truncate
the rest of the report text after the comm= field in the audit, losing fields.

Use get_task_comm() to get a copy while acquiring the task_lock to prevent
this and to prevent the result from being a mixture of old and new values of
comm.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:56 -04:00
Richard Guy Briggs f874738e8c audit: remove open_arg() function that is never used
open_arg() was added in commit 55669bfa "audit: AUDIT_PERM support"
and never used.  Remove it.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:55 -04:00
Richard Guy Briggs 9ef9151477 audit: correct AUDIT_GET_FEATURE return message type
When an AUDIT_GET_FEATURE message is sent from userspace to the kernel, it
should reply with a message tagged as an AUDIT_GET_FEATURE type with a struct
audit_feature.  The current reply is a message tagged as an AUDIT_GET
type with a struct audit_feature.

This appears to have been a cut-and-paste-eo in commit b0fed40.

Reported-by: Steve Grubb <sgrubb@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:55 -04:00
Richard Guy Briggs 54e05eddbe audit: set nlmsg_len for multicast messages.
Report:
	Looking at your example code in
	http://people.redhat.com/rbriggs/audit-multicast-listen/audit-multicast-listen.c,
	it seems that nlmsg_len field in the received messages is supposed to
	contain the length of the header + payload, but it is always set to the
	size of the header only, i.e. 16. The example program works, because
	the printf format specifies the minimum width, not "precision", so it
	simply prints out the payload until the first zero byte. This isn't too
	much of a problem, but precludes the use of recvmmsg, iiuc?

	(gdb) p *(struct nlmsghdr*)nlh
	$14 = {nlmsg_len = 16, nlmsg_type = 1100, nlmsg_flags = 0, nlmsg_seq = 0, nlmsg_pid = 9910}

The only time nlmsg_len would have been updated was at audit_buffer_alloc()
inside audit_log_start() and never updated after.  It should arguably be done
in audit_log_vformat(), but would be more efficient in audit_log_end().

Reported-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:54 -04:00
Richard Guy Briggs 219ca39427 audit: use union for audit_field values since they are mutually exclusive
Since only one of val, uid, gid and lsm* are used at any given time, combine
them to reduce the size of the struct audit_field.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:53 -04:00
Burn Alting e7df61f4d1 audit: invalid op= values for rules
Various audit events dealing with adding, removing and updating rules result in
invalid values set for the op keys which result in embedded spaces in op=
values.

The invalid values are
        op="add rule"       set in kernel/auditfilter.c
        op="remove rule"    set in kernel/auditfilter.c
        op="remove rule"    set in kernel/audit_tree.c
        op="updated rules"  set in kernel/audit_watch.c
        op="remove rule"    set in kernel/audit_watch.c

Replace the space in the above values with an underscore character ('_').

Coded-by: Burn Alting <burn@swtf.dyndns.org>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:53 -04:00
Richard Guy Briggs 01478d7d60 audit: use atomic_t to simplify audit_serial()
Since there is already a primitive to do this operation in the atomic_t, use it
to simplify audit_serial().

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:52 -04:00
Fabian Frederick 6eed9b2613 kernel/audit.c: use ARRAY_SIZE instead of sizeof/sizeof[0]
Use kernel.h definition.

Cc: Eric Paris <eparis@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:51 -04:00
Richard Guy Briggs 691e6d59d2 audit: reduce scope of audit_log_fcaps
audit_log_fcaps() isn't used outside kernel/audit.c.  Reduce its scope.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:51 -04:00
Richard Guy Briggs c0a8d9b069 audit: reduce scope of audit_net_id
audit_net_id isn't used outside kernel/audit.c.  Reduce its scope.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
2014-09-23 16:37:50 -04:00
Richard Guy Briggs b4f0d3755c audit: x86: drop arch from __audit_syscall_entry() interface
Since the arch is found locally in __audit_syscall_entry(), there is no need to
pass it in as a parameter.  Delete it from the parameter list.

x86* was the only arch to call __audit_syscall_entry() directly and did so from
assembly code.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-audit@redhat.com
Signed-off-by: Eric Paris <eparis@redhat.com>

---

As this patch relies on changes in the audit tree, I think it
appropriate to send it through my tree rather than the x86 tree.
2014-09-23 16:21:28 -04:00
Richard Guy Briggs 84db564aad audit: add arch field to seccomp event log
The AUDIT_SECCOMP record looks something like this:

type=SECCOMP msg=audit(1373478171.953:32775): auid=4325 uid=4325 gid=4325 ses=1 subj=unconfined_u:unconfined_r:unconfined_t:s0 pid=12381 comm="test" sig=31 syscall=231 compat=0 ip=0x39ea8bca89 code=0x0

In order to determine what syscall 231 maps to, we need to have the arch= field right before it.

To see the event, compile this test.c program:

=====
int main(void)
{
        return seccomp_load(seccomp_init(SCMP_ACT_KILL));
}
=====

gcc -g test.c -o test -lseccomp

After running the program, find the record by:  ausearch --start recent -m SECCOMP -i

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
signed-off-by: Eric Paris <eparis@redhat.com>
2014-09-23 16:21:26 -04:00
Richard Guy Briggs 4a99854c58 audit: __audit_syscall_entry: ignore arch arg and call syscall_get_arch() directly
Since every arch should have syscall_get_arch() defined, stop using the
function argument and just collect this ourselves.  We do not drop the
argument as fixing some code paths (in assembly) to not pass this first
argument is non-trivial.  The argument will be dropped when that is
fixed.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
2014-09-23 16:21:26 -04:00
David S. Miller 1f6d80358d Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts:
	arch/mips/net/bpf_jit.c
	drivers/net/can/flexcan.c

Both the flexcan and MIPS bpf_jit conflicts were cases of simple
overlapping changes.

Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-23 12:09:27 -04:00
Linus Torvalds 324c7b62d0 Merge branch 'for-3.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fix from Tejun Heo:
 "One late fix for cgroup.

  I was waiting for another set of fixes for a long-standing obscure
   cpuset bug but am not sure whether they'll be ready before v3.17
  release.  This one is a simple fix for a mutex unlock balance bug in
  an allocation failure path in pidlist_array_load().

  The bug was introduced in v3.14 and the fix is tagged for -stable"

* 'for-3.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: fix unbalanced locking
2014-09-23 09:06:18 -07:00
Josh Triplett 3cf6b0151b Merge branches 'tiny/bloat-o-meter-no-SyS', 'tiny/more-procless', 'tiny/no-advice', 'tiny/tinyconfig' and 'tiny/x86-boot-compressed-use-yn' into tiny/next 2014-09-22 23:14:40 -07:00
Ingo Molnar 6273143359 Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
Pull the v3.18 RCU changes from Paul E. McKenney:

"
  * Update RCU documentation.  These were posted to LKML at
    https://lkml.org/lkml/2014/8/28/378.

  * Miscellaneous fixes.  These were posted to LKML at
    https://lkml.org/lkml/2014/8/28/386.  An additional fix that
    eliminates a documented (but now inconvenient) deadlock between
    RCU hotplug and expedited grace periods was posted at
    https://lkml.org/lkml/2014/8/28/573.

  * Changes related to No-CBs CPUs and NO_HZ_FULL.  These were posted
    to LKML at https://lkml.org/lkml/2014/8/28/412.

  * Torture-test updates.  These were posted to LKML at
    https://lkml.org/lkml/2014/8/28/546 and at
    https://lkml.org/lkml/2014/9/11/1114.

  * RCU-tasks implementation.  These were posted to LKML at
    https://lkml.org/lkml/2014/8/28/540.
"

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-23 07:21:42 +02:00
Tomasz Figa a4a8c2c496 ARM: exynos: Move to generic PM domain DT bindings
This patch moves Exynos PM domain code to use the new generic PM domain
look-up framework introduced in previous patches, thus also allowing
the new code to be compiled with CONFIG_ARCH_EXYNOS.

This patch was originally submitted by Tomasz Figa when he was employed
by Samsung.

Link: http://marc.info/?l=linux-pm&m=139955336002083&w=2
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-22 15:57:40 +02:00
Tomasz Figa aa42240ab2 PM / Domains: Add generic OF-based PM domain look-up
This patch introduces generic code to perform PM domain look-up using
device tree and automatically bind devices to their PM domains.

Generic device tree bindings are introduced to specify PM domains of
devices in their device tree nodes.

Backwards compatibility with legacy Samsung-specific PM domain bindings
is provided, but for now the new code is not compiled when
CONFIG_ARCH_EXYNOS is selected to avoid collision with legacy code.
This will change as soon as the Exynos PM domain code gets converted to
use the generic framework in further patch.

This patch was originally submitted by Tomasz Figa when he was employed
by Samsung.

Link: http://marc.info/?l=linux-pm&m=139955349702152&w=2
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-22 15:57:40 +02:00
Todd E Brandt 0cadc70282 PM / sleep: new suspend_resume trace event for console resume
This patch adds another suspend_resume trace event for analyze_suspend
to capture. The resume_console call can take several hundred milliseconds
if the printk buffer is full of debug info. The tool will now inform
testers of the wasted time and encourage them to disable it in
production builds.

Signed-off-by: Todd Brandt <todd.e.brandt@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-22 14:53:23 +02:00
Zhihui Zhang 9c58c79a8a sched: Clean up some typos and grammatical errors in code/comments
Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com>
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1411262676-19928-1-git-send-email-zzhsuny@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-21 09:00:02 +02:00
Zefan Li 0c7bf3e8ca cgroup: remove redundant variable in cgroup_mount()
Both pinned_sb and new_sb indicate if a new superblock is needed,
so we can just remove new_sb.

Note now we must check if kernfs_tryget_sb() returns NULL, because
when it returns NULL, kernfs_mount() may still re-use an existing
superblock, which is just allocated by another concurent mount.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-20 13:09:35 -04:00
Zefan Li 3e2cd91ab9 cgroup: fix missing unlock in cgroup_release_agent()
The patch 971ff4935538: "cgroup: use a per-cgroup work for release
agent" from Sep 18, 2014, leads to the following static checker
warning:

	kernel/cgroup.c:5310 cgroup_release_agent()
	warn: 'mutex:&cgroup_mutex' is sometimes locked here and sometimes unlocked.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-20 12:23:35 -04:00
Linus Torvalds 598a0c7d09 Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Ingo Molnar:
 "Two kernel side fixes: a kprobes fix and a perf_remove_from_context()
  fix (which does not yet fix the migration bug which is WIP)"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Fix a race condition in perf_remove_from_context()
  kprobes/x86: Free 'optinsn' cache when range check fails
2014-09-19 10:31:36 -07:00
Zefan Li a25eb52e81 cgroup: remove CGRP_RELEASABLE flag
We call put_css_set() after setting CGRP_RELEASABLE flag in
cgroup_task_migrate(), but in other places we call it without setting
the flag. I don't see the necessity of this flag.

Moreover once the flag is set, it will never be cleared, unless writing
to the notify_on_release control file, so it can be quite confusing
if we look at the output of debug.releasable.

  # mount -t cgroup -o debug xxx /cgroup
  # mkdir /cgroup/child
  # cat /cgroup/child/debug.releasable
  0   <-- shows 0 though the cgroup is empty
  # echo $$ > /cgroup/child/tasks
  # cat /cgroup/child/debug.releasable
  0
  # echo $$ > /cgroup/tasks && echo $$ > /cgroup/child/tasks
  # cat /proc/child/debug.releasable
  1   <-- shows 1 though the cgroup is not empty

This patch removes the flag, and now debug.releasable shows if the
cgroup is empty or not.

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-19 09:29:32 -04:00
Zefan Li 4e2ba65068 perf/cgroup: Remove perf_put_cgroup()
Commit 5a17f543ed ("cgroup: improve css_from_dir() into css_tryget_from_dir()")
removed perf_tryget_cgroup(), so let's also remove perf_put_cgroup().

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-19 09:17:47 -04:00
Vincent Guittot bd61c98f9b sched: Test the CPU's capacity in wake_affine()
Currently the task always wakes affine on this_cpu if the latter is idle.
Before waking up the task on this_cpu, we check that this_cpu capacity is not
significantly reduced because of RT tasks or irq activity.

Use case where the number of irq and/or the time spent under irq is important
will take benefit of this because the task that is woken up by irq or softirq
will not use the same CPU than irq (and softirq) but a idle one.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: preeti@linux.vnet.ibm.com
Cc: riel@redhat.com
Cc: Morten.Rasmussen@arm.com
Cc: efault@gmx.de
Cc: nicolas.pitre@linaro.org
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409051215-16788-8-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:28 +02:00
Vincent Guittot 26bc3c50d3 sched: Allow all architectures to set 'capacity_orig'
'capacity_orig' is only changed for systems with an SMT sched_domain level in order
to reflect the lower capacity of CPUs. Heterogenous systems also have to reflect an
original capacity that is different from the default value.

Create a more generic function arch_scale_cpu_capacity that can be also used by
non SMT platforms to set capacity_orig.

The __weak implementation of arch_scale_cpu_capacity() is the previous SMT variant,
in order to keep backward compatibility with the use of capacity_orig.

arch_scale_smt_capacity() and default_scale_smt_capacity() have been removed as
they were not used elsewhere than in arch_scale_cpu_capacity().

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Reviewed-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
[ Added default_scale_cpu_capacity() back. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: riel@redhat.com
Cc: Morten.Rasmussen@arm.com
Cc: efault@gmx.de
Cc: nicolas.pitre@linaro.org
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409051215-16788-5-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:27 +02:00
Vincent Guittot 65fdac08c2 sched: Fix avg_load computation
The computation of avg_load and avg_load_per_task should only take into
account the number of CFS tasks. The non-CFS tasks are already taken into
account by decreasing the CPU's capacity and they will be tracked in the
CPU's utilization (group_utilization) of the next patches.

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: riel@redhat.com
Cc: Morten.Rasmussen@arm.com
Cc: efault@gmx.de
Cc: nicolas.pitre@linaro.org
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409051215-16788-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:26 +02:00
Vincent Guittot 05bfb65f52 sched: Remove a wake_affine() condition
In wake_affine() I have tried to understand the meaning of the condition:

 (this_load <= load &&
  this_load + target_load(prev_cpu, idx) <= tl_per_task)

but I failed to find a use case that can take advantage of it and I haven't
found clear description in the previous commit's log.

Futhermore, the comment of the condition refers to the task_hot function that
was used before being replaced by the current condition:

/*
 * This domain has SD_WAKE_AFFINE and
 * p is cache cold in this domain, and
 * there is no bad imbalance.
 */

If we look more deeply the below condition:

 this_load + target_load(prev_cpu, idx) <= tl_per_task

When sync is clear, we have:

 tl_per_task = runnable_load_avg / nr_running
 this_load = max(runnable_load_avg, cpuload[idx])
 target_load =  max(runnable_load_avg', cpuload'[idx])

It implies that runnable_load_avg == 0 and nr_running <= 1 in order to match the
condition. This implies that runnable_load_avg == 0 too because of the
condition: this_load <= load.

but if this _load is null, 'balanced' is already set and the test is redundant.

If sync is set, it's not as straight forward as above (especially if cgroup
are involved) but the policy should be similar as we have removed a task that's
going to sleep in order to get a more accurate load and this_load values.

The current conclusion is that these additional condition don't give any benefit
so we can remove them.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: preeti@linux.vnet.ibm.com
Cc: riel@redhat.com
Cc: Morten.Rasmussen@arm.com
Cc: efault@gmx.de
Cc: nicolas.pitre@linaro.org
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409051215-16788-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:25 +02:00
Vincent Guittot afdeee0510 sched: Fix imbalance flag reset
The imbalance flag can stay set whereas there is no imbalance.

Let assume that we have 3 tasks that run on a dual cores /dual cluster system.
We will have some idle load balance which are triggered during tick.
Unfortunately, the tick is also used to queue background work so we can reach
the situation where short work has been queued on a CPU which already runs a
task. The load balance will detect this imbalance (2 tasks on 1 CPU and an idle
CPU) and will try to pull the waiting task on the idle CPU. The waiting task is
a worker thread that is pinned on a CPU so an imbalance due to pinned task is
detected and the imbalance flag is set.

Then, we will not be able to clear the flag because we have at most 1 task on
each CPU but the imbalance flag will trig to useless active load balance
between the idle CPU and the busy CPU.

We need to reset of the imbalance flag as soon as we have reached a balanced
state. If all tasks are pinned, we don't consider that as a balanced state and
let the imbalance flag set.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: riel@redhat.com
Cc: Morten.Rasmussen@arm.com
Cc: efault@gmx.de
Cc: nicolas.pitre@linaro.org
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409051215-16788-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:24 +02:00
Aaron Tomlin 0d9e26329b sched: Add default-disabled option to BUG() when stack end location is overwritten
Currently in the event of a stack overrun a call to schedule()
does not check for this type of corruption. This corruption is
often silent and can go unnoticed. However once the corrupted
region is examined at a later stage, the outcome is undefined
and often results in a sporadic page fault which cannot be
handled.

This patch checks for a stack overrun and takes appropriate
action since the damage is already done, there is no point
in continuing.

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dzickus@redhat.com
Cc: bmr@redhat.com
Cc: jcastillo@redhat.com
Cc: oleg@redhat.com
Cc: riel@redhat.com
Cc: prarit@redhat.com
Cc: jgh@redhat.com
Cc: minchan@kernel.org
Cc: mpe@ellerman.id.au
Cc: tglx@linutronix.de
Cc: rostedt@goodmis.org
Cc: hannes@cmpxchg.org
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lubomir Rintel <lkundrak@v3.sk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1410527779-8133-4-git-send-email-atomlin@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:24 +02:00
Aaron Tomlin a70857e46d sched: Add helper for task stack page overrun checking
This facility is used in a few places so let's introduce
a helper function to improve code readability.

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dzickus@redhat.com
Cc: bmr@redhat.com
Cc: jcastillo@redhat.com
Cc: oleg@redhat.com
Cc: riel@redhat.com
Cc: prarit@redhat.com
Cc: jgh@redhat.com
Cc: minchan@kernel.org
Cc: mpe@ellerman.id.au
Cc: tglx@linutronix.de
Cc: hannes@cmpxchg.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1410527779-8133-3-git-send-email-atomlin@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:23 +02:00
Aaron Tomlin d4311ff1a8 init/main.c: Give init_task a canary
Tasks get their end of stack set to STACK_END_MAGIC with the
aim to catch stack overruns. Currently this feature does not
apply to init_task. This patch removes this restriction.

Note that a similar patch was posted by Prarit Bhargava
some time ago but was never merged:

  http://marc.info/?l=linux-kernel&m=127144305403241&w=2

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dzickus@redhat.com
Cc: bmr@redhat.com
Cc: jcastillo@redhat.com
Cc: jgh@redhat.com
Cc: minchan@kernel.org
Cc: tglx@linutronix.de
Cc: hannes@cmpxchg.org
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Daeseok Youn <daeseok.youn@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1410527779-8133-2-git-send-email-atomlin@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:22 +02:00
Kirill Tkhai a15b12ac36 sched: Do not stop cpu in set_cpus_allowed_ptr() if task is not running
If a task is queued but not running on it rq, we can simply migrate
it without migration thread and switching of context.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1410519814.3569.7.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:21 +02:00
Kirill Tkhai 1ba93d4272 sched/dl: Simplify pick_dl_task()
1) Nobody calls pick_dl_task() with negative cpu, it's old RT leftover.

2) If p->nr_cpus_allowed is 1, than the affinity has just been changed
  in set_cpus_allowed_ptr(); we'll pick it just earlier than migration
  thread.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410529340.3569.27.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:20 +02:00
Kirill Tkhai f3f1768f89 sched/rt: Remove useless if from cleanup pick_next_task_rt()
_pick_next_task_rt() never returns NULL.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410529321.3569.26.camel@tkhai
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:20 +02:00
Kirill Tkhai f3cd1c4ec0 sched/core: Use put_prev_task() accessor where possible
Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410529300.3569.25.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:19 +02:00
Kirill Tkhai a8edd07532 sched/fair: cleanup: Remove useless assignment in select_task_rq_fair()
new_cpu is reassigned below, so we do not need this here.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410529276.3569.24.camel@tkhai
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:18 +02:00
Kirill Tkhai f139caf2e8 sched, cleanup, treewide: Remove set_current_state(TASK_RUNNING) after schedule()
schedule(), io_schedule() and schedule_timeout() always return
with TASK_RUNNING state set, so one more setting is unnecessary.

(All places in patch are visible good, only exception is
 kiblnd_scheduler() from:

      drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c

 Its schedule() is one line above standard 3 lines of unified diff)

No places where set_current_state() is used for mb().

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410529254.3569.23.camel@tkhai
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Anil Belur <askb23@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: David Airlie <airlied@linux.ie>
Cc: David Howells <dhowells@redhat.com>
Cc: Dmitry Eremin <dmitry.eremin@intel.com>
Cc: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Isaac Huang <he.huang@intel.com>
Cc: James E.J. Bottomley <JBottomley@parallels.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Liang Zhen <liang.zhen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masaru Nomura <massa.nomura@gmail.com>
Cc: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Oleg Drokin <green@linuxhacker.ru>
Cc: Peng Tao <bergwolf@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Robert Love <robert.w.love@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Ursula Braun <ursula.braun@de.ibm.com>
Cc: Zi Shen Lim <zlim.lnx@gmail.com>
Cc: devel@driverdev.osuosl.org
Cc: dm-devel@redhat.com
Cc: dri-devel@lists.freedesktop.org
Cc: fcoe-devel@open-fcoe.org
Cc: jfs-discussion@lists.sourceforge.net
Cc: linux390@de.ibm.com
Cc: linux-afs@lists.infradead.org
Cc: linux-cris-kernel@axis.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-nfs@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linux-raid@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: qla2xxx-upstream@qlogic.com
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: user-mode-linux-user@lists.sourceforge.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:17 +02:00
Rik van Riel 9c368b5b6e sched, time: Fix lock inversion in thread_group_cputime()
The sig->stats_lock nests inside the tasklist_lock and the
sighand->siglock in __exit_signal and wait_task_zombie.

However, both of those locks can be taken from irq context,
which means we need to use the interrupt safe variant of
read_seqbegin_or_lock. This blocks interrupts when the "lock"
branch is taken (seq is odd), preventing the lock inversion.

On the first (lockless) pass through the loop, irqs are not
blocked.

Reported-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: prarit@redhat.com
Cc: oleg@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1410527535-9814-3-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:17 +02:00
Chuansheng Liu c6f4459fc3 smp: Add new wake_up_all_idle_cpus() function
Currently kick_all_cpus_sync() can break non-polling idle cpus
thru IPI interrupts.

But sometimes we need to break the polling idle cpus immediately
to reselect the suitable c-state, also for non-idle cpus, we need
to do nothing if we try to wake up them.

Here adding one new function wake_up_all_idle_cpus() to let all cpus
out of idle based on function wake_up_if_idle().

Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: daniel.lezcano@linaro.org
Cc: rjw@rjwysocki.net
Cc: linux-pm@vger.kernel.org
Cc: changcheng.liu@intel.com
Cc: xiaoming.wang@intel.com
Cc: souvik.k.chakravarty@intel.com
Cc: luto@amacapital.net
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1409815075-4180-2-git-send-email-chuansheng.liu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:15 +02:00
Chuansheng Liu f6be8af1c9 sched: Add new API wake_up_if_idle() to wake up the idle cpu
Implementing one new API wake_up_if_idle(), which is used to
wake up the idle CPU.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: daniel.lezcano@linaro.org
Cc: rjw@rjwysocki.net
Cc: linux-pm@vger.kernel.org
Cc: changcheng.liu@intel.com
Cc: xiaoming.wang@intel.com
Cc: souvik.k.chakravarty@intel.com
Cc: chuansheng.liu@intel.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409815075-4180-1-git-send-email-chuansheng.liu@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:14 +02:00
Rik van Riel ba7e5a279e sched/numa: Use select_idle_sibling() to select a destination for task_numa_move()
The code in task_numa_compare() will only examine at most one idle CPU per node,
because they all have the same score. However, some idle CPUs are better
candidates than others, due to busy or idle SMT siblings, etc...

The scheduler has logic to find the best CPU within an LLC to place a
task. The NUMA code should probably use it.

This seems to reduce the standard deviation for single instance SPECjbb2005
with a low warehouse count on my 4 node test system.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140904163530.189d410a@cuia.bos.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:14 +02:00
Paul E. McKenney dd56af42bd rcu: Eliminate deadlock between CPU hotplug and expedited grace periods
Currently, the expedited grace-period primitives do get_online_cpus().
This greatly simplifies their implementation, but means that calls
to them holding locks that are acquired by CPU-hotplug notifiers (to
say nothing of calls to these primitives from CPU-hotplug notifiers)
can deadlock.  But this is starting to become inconvenient, as can be
seen here: https://lkml.org/lkml/2014/8/5/754.  The problem in this
case is that some developers need to acquire a mutex from a CPU-hotplug
notifier, but also need to hold it across a synchronize_rcu_expedited().
As noted above, this currently results in deadlock.

This commit avoids the deadlock and retains the simplicity by creating
a try_get_online_cpus(), which returns false if the get_online_cpus()
reference count could not immediately be incremented.  If a call to
try_get_online_cpus() returns true, the expedited primitives operate as
before.  If a call returns false, the expedited primitives fall back to
normal grace-period operations.  This falling back of course results in
increased grace-period latency, but only during times when CPU hotplug
operations are actually in flight.  The effect should therefore be
negligible during normal operation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Tested-by: Lan Tianyu <tianyu.lan@intel.com>
2014-09-18 16:22:27 -07:00
Zefan Li 52de4779f2 cpuset: simplify proc_cpuset_show()
Use the ONE macro instead of REG, and we can simplify proc_cpuset_show().

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18 13:27:23 -04:00
Zefan Li 006f4ac497 cgroup: simplify proc_cgroup_show()
Use the ONE macro instead of REG, and we can simplify proc_cgroup_show().

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18 13:27:23 -04:00
Zefan Li 971ff49355 cgroup: use a per-cgroup work for release agent
Instead of using a global work to schedule release agent on removable
cgroups, we change to use a per-cgroup work to do this, which makes
the code much simpler.

v2: use a dedicated work instead of reusing css->destroy_work. (Tejun)

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18 13:14:22 -04:00
Zefan Li eb4aec84d6 cgroup: fix unbalanced locking
cgroup_pidlist_start() holds cgrp->pidlist_mutex and then calls
pidlist_array_load(), and cgroup_pidlist_stop() releases the mutex.

It is wrong that we release the mutex in the failure path in
pidlist_array_load(), because cgroup_pidlist_stop() will be called
no matter if cgroup_pidlist_start() returns errno or not.

Fixes: 4bac00d16a
Cc: <stable@vger.kernel.org> # 3.14+
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
2014-09-18 12:32:52 -04:00
Li Zefan 0c8fc2c121 cgroup: remove bogus comments
We never grab cgroup mutex in fork and exit paths no matter whether
notify_on_release is set or not.

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18 06:34:16 +09:00
Li Zefan 244bb9a633 cgroup: remove redundant code in cgroup_rmdir()
We no longer clear kn->priv in cgroup_rmdir(), so we don't need
to get an extra refcnt.

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18 06:34:15 +09:00
Li Zefan 6213daab25 cgroup: remove some useless forward declarations
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18 06:34:15 +09:00
Tejun Heo 9253b279f4 Merge branch 'for-3.17-fixes' of ra.kernel.org:/pub/scm/linux/kernel/git/tj/cgroup into for-3.18
Pull to receive a4189487da ("cgroup: delay the clearing of
cgrp->kn->priv") for the scheduled clean up patches.

Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-18 06:29:05 +09:00
Paul E. McKenney 59da22a020 rcutorture: Rename rcutorture_runnable parameter
This commit changes rcutorture_runnable to torture_runnable, which is
consistent with the names of the other parameters and is a bit shorter
as well.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:44 -07:00
Davidlohr Bueso 630952c22b locktorture: Introduce torture context
The amount of global variables is getting pretty ugly. Group variables
related to the execution (ie: not parameters) in a new context structure.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:40 -07:00
Davidlohr Bueso 4a3b427f0b locktorture: Support rwsems
We can easily do so with our new reader lock support. Just an arbitrary
design default: readers have higher (5x) critical region latencies than
writers: 50 ms and 10 ms, respectively.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:36 -07:00
Davidlohr Bueso 4f6332c1dc locktorture: Add infrastructure for torturing read locks
Most of it is based on what we already have for writers. This allows
readers to be very independent (and thus configurable), enabling
future module parameters to control things such as rw distribution.
Furthermore, readers have their own delaying function, allowing us
to test different rw critical region latencies, and stress locking
internals. Similarly, statistics, for now will only serve for the
number of lock acquisitions -- as opposed to writers, readers have
no failure detection.

In addition, introduce a new nreaders_stress module parameter. The
default number of readers will be the same number of writers threads.
Writer threads are interleaved with readers. Documentation is updated,
respectively.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:07 -07:00
Davidlohr Bueso d36a7a0d5e torture: Address race in module cleanup
When performing module cleanups by calling torture_cleanup() the
'torture_type' string in nullified However, callers are not necessarily
done, and might still need to reference the variable. This impacts
both rcutorture and locktorture, causing printing things like:

[   94.226618] (null)-torture: Stopping lock_torture_writer task
[   94.226624] (null)-torture: Stopping lock_torture_stats task

Thus delay this operation until the very end of the cleanup process.
The consequence (which shouldn't matter for this kid of program) is,
of course, that we delay the window between rmmod and modprobing,
for instance in module_torture_begin().

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:06 -07:00
Davidlohr Bueso 1e6757a921 locktorture: Make statistics generic
The statistics structure can serve well for both reader and writer
locks, thus simply rename some fields that mention 'write' and leave
the declaration of lwsa.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:05 -07:00
Davidlohr Bueso f095bfc0ea locktorture: Teach about lock debugging
Regular locks are very different than locks with debugging. For instance
for mutexes, debugging forces to only take the slowpaths. As such, the
locktorture module should take this into account when printing related
information -- specifically when printing user passed parameters, it seems
the right place for such info.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:41:04 -07:00
Davidlohr Bueso 42ddc75ddd locktorture: Support mutexes
Add a "mutex_lock" torture test. The main difference with the already
existing spinlock tests is that the latency of the critical region
is much larger. We randomly delay for (arbitrarily) either 500 ms or,
otherwise, 25 ms. While this can considerably reduce the amount of
writes compared to non blocking locks, if run long enough it can have
the same torturous effect. Furthermore it is more representative of
mutex hold times and can stress better things like thrashing.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 13:40:59 -07:00
Davidlohr Bueso 23a8e5c2d2 locktorture: Rename locktorture_runnable parameter
... to just 'torture_runnable'. It follows other variable naming
and is shorter.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-16 10:15:48 -07:00
Paul E. McKenney 96b4672703 Merge branch 'rcu-tasks.2014.09.10a' into HEAD
rcu-tasks.2014.09.10a: Add RCU-tasks flavor of RCU.
2014-09-16 10:10:44 -07:00
Paul E. McKenney e98d06dd6c Merge branches 'doc.2014.09.07a', 'fixes.2014.09.10a', 'nocb-nohz.2014.09.16b' and 'torture.2014.09.07a' into HEAD
doc.2014.09.07a: Documentation updates.
fixes.2014.09.10a: Miscellaneous fixes.
nocb-nohz.2014.09.16b: No-CBs CPUs and NO_HZ_FULL updates.
torture.2014.09.07a: Torture-test updates.
2014-09-16 10:08:34 -07:00
Paul E. McKenney c847f14217 rcu: Avoid misordering in nocb_leader_wait()
The NOCB follower wakeup ordering depends on the store to the tail
pointer happening before the wakeup.  However, because atomic_long_add()
does not return a value, it does not provide ordering guarantees, and
the locking in wake_up() only guarantees that the store will happen
before the unlock, which might be too late.  Even though this is only a
theoretical issue, this commit adds a smp_mb__after_atomic() after the
final atomic_long_add() to provide the needed ordering guarantee.

Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:03 -07:00
Paul E. McKenney 1772947bd0 rcu: Handle NOCB callbacks from irq-disabled idle code
If an RCU callback is queued on a no-CBs CPU from idle code with irqs
disabled, and if that CPU stays idle forever after, the callback will
never be invoked.  This commit therefore adds a check for this situation
in ____call_rcu_nocb(), invoking the RCU core solely for the purpose
of the ensuing return-to-idle transition.  (If the CPU doesn't return
to idle, the next scheduling-clock interrupt will fix things up.)

Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:03 -07:00
Paul E. McKenney 39953dfd40 rcu: Avoid misordering in __call_rcu_nocb_enqueue()
The NOCB leader wakeup ordering depends on the store to the header
happening before the check for the leader already being awake.  However,
because atomic_long_add() does not return a value, it does not provide
ordering guarantees, the incorrect comment in wake_nocb_leader()
notwithstanding.  This commit therefore adds a smp_mb__after_atomic()
after the final atomic_long_add() to provide the needed ordering
guarantee.

Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:03 -07:00
Paul E. McKenney 663e131090 rcu: Don't track sysidle state if no nohz_full= CPUs
If there are no nohz_full= CPUs, then there is currently no reason to
track sysidle state.  This commit therefore short-circuits this state
tracking if !tick_nohz_full_enabled().

Note that these checks will need to be revisited if nohz_full= state
can ever be changed at runtime.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:02 -07:00
Paul E. McKenney 417e8d2655 rcu: Eliminate redundant rcu_sysidle_state variable
Now that we have rcu_state_p, which references rcu_preempt_state for
TREE_PREEMPT_RCU and rcu_sched_state for TREE_RCU, we don't need a
separate rcu_sysidle_state variable.  This commit therefore eliminates
rcu_preempt_state in favor of rcu_state_p.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:02 -07:00
Pranith Kumar 22c2f66961 rcu: Check for have_rcu_nocb_mask instead of rcu_nocb_mask
If we configure a kernel with CONFIG_NOCB_CPU=y, CONFIG_RCU_NOCB_CPU_NONE=y and
CONFIG_CPUMASK_OFFSTACK=n and do not pass in a rcu_nocb= boot parameter, the
cpumask rcu_nocb_mask can be garbage instead of NULL.

Hence this commit replaces checks for rcu_nocb_mask == NULL with a check for
have_rcu_nocb_mask.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:02 -07:00
Paul E. McKenney 35ce7f29a4 rcu: Create rcuo kthreads only for onlined CPUs
RCU currently uses for_each_possible_cpu() to spawn rcuo kthreads,
which can result in more rcuo kthreads than one would expect, for
example, derRichard reported 64 CPUs worth of rcuo kthreads on an
8-CPU image.  This commit therefore creates rcuo kthreads only for
those CPUs that actually come online.

This was reported by derRichard on the OFTC IRC network.

Reported-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:02 -07:00
Paul E. McKenney 9386c0b75d rcu: Rationalize kthread spawning
Currently, RCU spawns kthreads from several different early_initcall()
functions.  Although this has served RCU well for quite some time,
as more kthreads are added a more deterministic approach is required.
This commit therefore causes all of RCU's early-boot kthreads to be
spawned from a single early_initcall() function.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:01 -07:00
Pranith Kumar f4aa84ba24 rcu: Return false instead of 0 in rcu_nocb_adopt_orphan_cbs()
Return false instead of 0 in rcu_nocb_adopt_orphan_cbs() as this has
bool as return type.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:01 -07:00
Pranith Kumar 4afc7e269b rcu: Use false for return in __call_rcu_nocb()
Return false instead of 0 in __call_rcu_nocb() as this has bool as
return type.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:01 -07:00
Pranith Kumar 0a9e1e111b rcu: Use true/false for return in rcu_nocb_adopt_orphan_cbs()
Return true/false in rcu_nocb_adopt_orphan_cbs() instead of 0/1 as
this function has return type of bool.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:00 -07:00
Pranith Kumar c271d3a957 rcu: Use true/false for return in __call_rcu_nocb()
Return true/false instead of 0/1 in __call_rcu_nocb() as this returns a
bool type.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:00 -07:00
Pranith Kumar 949cccdbe6 rcu: Check the return value of zalloc_cpumask_var()
This commit checks the return value of the zalloc_cpumask_var() used for
allocating cpumask for rcu_nocb_mask.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:08:00 -07:00
Paul E. McKenney f4579fc57c rcu: Fix attempt to avoid unsolicited offloading of callbacks
Commit b58cc46c5f (rcu: Don't offload callbacks unless specifically
requested) failed to adjust the callback lists of the CPUs that are
known to be no-CBs CPUs only because they are also nohz_full= CPUs.
This failure can result in callbacks that are posted during early boot
getting stranded on nxtlist for CPUs whose no-CBs property becomes
apparent late, and there can also be spurious warnings about offline
CPUs posting callbacks.

This commit fixes these problems by adding an early-boot rcu_init_nohz()
that properly initializes the no-CBs CPUs.

Note that kernels built with CONFIG_RCU_NOCB_CPU_ALL=y or with
CONFIG_RCU_NOCB_CPU=n do not exhibit this bug.  Neither do kernels
booted without the nohz_full= boot parameter.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2014-09-16 10:07:59 -07:00
Jiri Olsa c88f209613 perf: Do not check PERF_EVENT_STATE_EXIT on syscall read path
Revert PERF_EVENT_STATE_EXIT check on read syscall path.
It breaks standard way to read counter, which is to open
the counter, wait for the monitored process to die and
read the counter.

Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Stephane Eranian <eranian@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/20140908143107.GG17728@krava.brq.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-16 10:30:36 +02:00
Davidlohr Bueso db0e716a15 locking/rwsem: Move EXPORT_SYMBOL() lines to follow function definition
rw-semaphore is the only type of lock doing this ugliness of
exporting at the end of the file.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: dave@stgolabs.net
Cc: peterz@infradead.org
Link: http://lkml.kernel.org/r/1410500066-5909-1-git-send-email-dave@stgolabs.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-16 09:49:01 +02:00
Linus Torvalds 1536340e7c Merge branches 'locking-urgent-for-linus' and 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull futex and timer fixes from Thomas Gleixner:
 "A oneliner bugfix for the jinxed futex code:

   - Drop hash bucket lock in the error exit path.  I really could slap
     myself for intruducing that bug while fixing all the other horror
     in that code three month ago ...

  and the timer department is not too proud about the following fixes:

   - Deal with a long standing rounding bug in the timeval to jiffies
     conversion.  It's a real issue and this fix fell through the cracks
     for quite some time.

   - Another round of alarmtimer fixes.  Finally this code gets used
     more widely and the subtle issues hidden for quite some time are
     noticed and fixed.  Nothing really exciting, just the itty bitty
     details which bite the serious users here and there"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Unlock hb->lock in futex_wait_requeue_pi() error path

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  alarmtimer: Lock k_itimer during timer callback
  alarmtimer: Do not signal SIGEV_NONE timers
  alarmtimer: Return relative times in timer_gettime
  jiffies: Fix timeval conversion to jiffies
2014-09-13 14:22:12 -07:00
Frederic Weisbecker 9b01f5bf39 nohz: nohz full depends on irq work self IPI support
The nohz full functionality depends on IRQ work to trigger its own
interrupts. As it's used to restart the tick, we can't rely on the tick
fallback for irq work callbacks, ie: we can't use the tick to restart
the tick itself.

Lets reject the full dynticks initialization if that arch support isn't
available.

As a side effect, this makes sure that nohz kick is never called from
the tick. That otherwise would result in illegal hrtimer self-cancellation
and lockup.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-09-13 18:46:41 +02:00
Frederic Weisbecker 4327b15f64 nohz: Consolidate nohz full init code
The supports for CONFIG_NO_HZ_FULL_ALL=y and the nohz_full= kernel
parameter both have their own way to do the same thing: allocate
full dynticks cpumasks, fill them and initialize some state variables.

Lets consolidate that all in the same place.

While at it, convert some regular printk message to warnings when
fundamental allocations fail.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-09-13 18:46:40 +02:00
Frederic Weisbecker 76a33061b9 irq_work: Force raised irq work to run on irq work interrupt
The nohz full kick, which restarts the tick when any resource depend
on it, can't be executed anywhere given the operation it does on timers.
If it is called from the scheduler or timers code, chances are that
we run into a deadlock.

This is why we run the nohz full kick from an irq work. That way we make
sure that the kick runs on a virgin context.

However if that's the case when irq work runs in its own dedicated
self-ipi, things are different for the big bunch of archs that don't
support the self triggered way. In order to support them, irq works are
also handled by the timer interrupt as fallback.

Now when irq works run on the timer interrupt, the context isn't blank.
More precisely, they can run in the context of the hrtimer that runs the
tick. But the nohz kick cancels and restarts this hrtimer and cancelling
an hrtimer from itself isn't allowed. This is why we run in an endless
loop:

	Kernel panic - not syncing: Watchdog detected hard LOCKUP on cpu 2
	CPU: 2 PID: 7538 Comm: kworker/u8:8 Not tainted 3.16.0+ #34
	Workqueue: btrfs-endio-write normal_work_helper [btrfs]
	 ffff880244c06c88 000000001b486fe1 ffff880244c06bf0 ffffffff8a7f1e37
	 ffffffff8ac52a18 ffff880244c06c78 ffffffff8a7ef928 0000000000000010
	 ffff880244c06c88 ffff880244c06c20 000000001b486fe1 0000000000000000
	Call Trace:
	 <NMI[<ffffffff8a7f1e37>] dump_stack+0x4e/0x7a
	 [<ffffffff8a7ef928>] panic+0xd4/0x207
	 [<ffffffff8a1450e8>] watchdog_overflow_callback+0x118/0x120
	 [<ffffffff8a186b0e>] __perf_event_overflow+0xae/0x350
	 [<ffffffff8a184f80>] ? perf_event_task_disable+0xa0/0xa0
	 [<ffffffff8a01a4cf>] ? x86_perf_event_set_period+0xbf/0x150
	 [<ffffffff8a187934>] perf_event_overflow+0x14/0x20
	 [<ffffffff8a020386>] intel_pmu_handle_irq+0x206/0x410
	 [<ffffffff8a01937b>] perf_event_nmi_handler+0x2b/0x50
	 [<ffffffff8a007b72>] nmi_handle+0xd2/0x390
	 [<ffffffff8a007aa5>] ? nmi_handle+0x5/0x390
	 [<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
	 [<ffffffff8a008062>] default_do_nmi+0x72/0x1c0
	 [<ffffffff8a008268>] do_nmi+0xb8/0x100
	 [<ffffffff8a7ff66a>] end_repeat_nmi+0x1e/0x2e
	 [<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
	 [<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
	 [<ffffffff8a0cb7f8>] ? match_held_lock+0x8/0x1b0
	 <<EOE><IRQ[<ffffffff8a0ccd2f>] lock_acquired+0xaf/0x450
	 [<ffffffff8a0f74c5>] ? lock_hrtimer_base.isra.20+0x25/0x50
	 [<ffffffff8a7fc678>] _raw_spin_lock_irqsave+0x78/0x90
	 [<ffffffff8a0f74c5>] ? lock_hrtimer_base.isra.20+0x25/0x50
	 [<ffffffff8a0f74c5>] lock_hrtimer_base.isra.20+0x25/0x50
	 [<ffffffff8a0f7723>] hrtimer_try_to_cancel+0x33/0x1e0
	 [<ffffffff8a0f78ea>] hrtimer_cancel+0x1a/0x30
	 [<ffffffff8a109237>] tick_nohz_restart+0x17/0x90
	 [<ffffffff8a10a213>] __tick_nohz_full_check+0xc3/0x100
	 [<ffffffff8a10a25e>] nohz_full_kick_work_func+0xe/0x10
	 [<ffffffff8a17c884>] irq_work_run_list+0x44/0x70
	 [<ffffffff8a17c8da>] irq_work_run+0x2a/0x50
	 [<ffffffff8a0f700b>] update_process_times+0x5b/0x70
	 [<ffffffff8a109005>] tick_sched_handle.isra.21+0x25/0x60
	 [<ffffffff8a109b81>] tick_sched_timer+0x41/0x60
	 [<ffffffff8a0f7aa2>] __run_hrtimer+0x72/0x470
	 [<ffffffff8a109b40>] ? tick_sched_do_timer+0xb0/0xb0
	 [<ffffffff8a0f8707>] hrtimer_interrupt+0x117/0x270
	 [<ffffffff8a034357>] local_apic_timer_interrupt+0x37/0x60
	 [<ffffffff8a80010f>] smp_apic_timer_interrupt+0x3f/0x50
	 [<ffffffff8a7fe52f>] apic_timer_interrupt+0x6f/0x80

To fix this we force non-lazy irq works to run on irq work self-IPIs
when available. That ability of the arch to trigger irq work self IPIs
is available with arch_irq_work_has_interrupt().

Reported-by: Catalin Iacob <iacobcatalin@gmail.com>
Reported-by: Dave Jones <davej@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-09-13 18:38:15 +02:00
Frederic Weisbecker a80e49e2cc nohz: Move nohz full init call to tick init
This way we unbloat a bit main.c and more importantly we initialize
nohz full after init_IRQ(). This dependency will be needed in further
patches because nohz full needs irq work to raise its own IRQ.
Information about the support for this ability on ARM64 is obtained on
init_IRQ() which initialize the pointer to __smp_call_function.

Since tick_init() is called right after init_IRQ(), this is a good place
to call tick_nohz_init() and prepare for that dependency.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-09-13 18:34:44 +02:00
Steven Rostedt (Red Hat) 3ddee63a09 ftrace: Only disable ftrace_enabled to test buffer in selftest
The ftrace_enabled variable is set to zero in the self tests to keep
delayed functions from being traced and messing with the checks. This
only needs to be done when the checks are being performed, otherwise,
if ftrace_enabled is off when calls back to the utility that is being
tested, it can cause errors to happen and the tests can fail with
false positives.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-12 20:48:49 -04:00
Steven Rostedt (Red Hat) 84bde62ca4 ftrace: Add sanity check when unregistering last ftrace_ops
When the last ftrace_ops is unregistered, all the function records should
have a zeroed flags value. Make sure that is the case when the last ftrace_ops
is unregistered.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-12 20:48:43 -04:00
Richard Larocque 474e941bed alarmtimer: Lock k_itimer during timer callback
Locks the k_itimer's it_lock member when handling the alarm timer's
expiry callback.

The regular posix timers defined in posix-timers.c have this lock held
during timout processing because their callbacks are routed through
posix_timer_fn().  The alarm timers follow a different path, so they
ought to grab the lock somewhere else.

Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: Richard Larocque <rlarocque@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-09-12 13:59:12 -07:00
Richard Larocque 265b81d23a alarmtimer: Do not signal SIGEV_NONE timers
Avoids sending a signal to alarm timers created with sigev_notify set to
SIGEV_NONE by checking for that special case in the timeout callback.

The regular posix timers avoid sending signals to SIGEV_NONE timers by
not scheduling any callbacks for them in the first place.  Although it
would be possible to do something similar for alarm timers, it's simpler
to handle this as a special case in the timeout.

Prior to this patch, the alarm timer would ignore the sigev_notify value
and try to deliver signals to the process anyway.  Even worse, the
sanity check for the value of sigev_signo is skipped when SIGEV_NONE was
specified, so the signal number could be bogus.  If sigev_signo was an
unitialized value (as it often would be if SIGEV_NONE is used), then
it's hard to predict which signal will be sent.

Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: Richard Larocque <rlarocque@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-09-12 13:59:12 -07:00
Richard Larocque e86fea7649 alarmtimer: Return relative times in timer_gettime
Returns the time remaining for an alarm timer, rather than the time at
which it is scheduled to expire.  If the timer has already expired or it
is not currently scheduled, the it_value's members are set to zero.

This new behavior matches that of the other posix-timers and the POSIX
specifications.

This is a change in user-visible behavior, and may break existing
applications.  Hopefully, few users rely on the old incorrect behavior.

Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Sharvil Nanavati <sharvil@google.com>
Signed-off-by: Richard Larocque <rlarocque@google.com>
[jstultz: minor style tweak]
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-09-12 13:59:11 -07:00
Andrew Hunter d78c9300c5 jiffies: Fix timeval conversion to jiffies
timeval_to_jiffies tried to round a timeval up to an integral number
of jiffies, but the logic for doing so was incorrect: intervals
corresponding to exactly N jiffies would become N+1. This manifested
itself particularly repeatedly stopping/starting an itimer:

setitimer(ITIMER_PROF, &val, NULL);
setitimer(ITIMER_PROF, NULL, &val);

would add a full tick to val, _even if it was exactly representable in
terms of jiffies_ (say, the result of a previous rounding.)  Doing
this repeatedly would cause unbounded growth in val.  So fix the math.

Here's what was wrong with the conversion: we essentially computed
(eliding seconds)

jiffies = usec  * (NSEC_PER_USEC/TICK_NSEC)

by using scaling arithmetic, which took the best approximation of
NSEC_PER_USEC/TICK_NSEC with denominator of 2^USEC_JIFFIE_SC =
x/(2^USEC_JIFFIE_SC), and computed:

jiffies = (usec * x) >> USEC_JIFFIE_SC

and rounded this calculation up in the intermediate form (since we
can't necessarily exactly represent TICK_NSEC in usec.) But the
scaling arithmetic is a (very slight) *over*approximation of the true
value; that is, instead of dividing by (1 usec/ 1 jiffie), we
effectively divided by (1 usec/1 jiffie)-epsilon (rounding
down). This would normally be fine, but we want to round timeouts up,
and we did so by adding 2^USEC_JIFFIE_SC - 1 before the shift; this
would be fine if our division was exact, but dividing this by the
slightly smaller factor was equivalent to adding just _over_ 1 to the
final result (instead of just _under_ 1, as desired.)

In particular, with HZ=1000, we consistently computed that 10000 usec
was 11 jiffies; the same was true for any exact multiple of
TICK_NSEC.

We could possibly still round in the intermediate form, adding
something less than 2^USEC_JIFFIE_SC - 1, but easier still is to
convert usec->nsec, round in nanoseconds, and then convert using
time*spec*_to_jiffies.  This adds one constant multiplication, and is
not observably slower in microbenchmarks on recent x86 hardware.

Tested: the following program:

int main() {
  struct itimerval zero = {{0, 0}, {0, 0}};
  /* Initially set to 10 ms. */
  struct itimerval initial = zero;
  initial.it_interval.tv_usec = 10000;
  setitimer(ITIMER_PROF, &initial, NULL);
  /* Save and restore several times. */
  for (size_t i = 0; i < 10; ++i) {
    struct itimerval prev;
    setitimer(ITIMER_PROF, &zero, &prev);
    /* on old kernels, this goes up by TICK_USEC every iteration */
    printf("previous value: %ld %ld %ld %ld\n",
           prev.it_interval.tv_sec, prev.it_interval.tv_usec,
           prev.it_value.tv_sec, prev.it_value.tv_usec);
    setitimer(ITIMER_PROF, &prev, NULL);
  }
    return 0;
}

Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Turner <pjt@google.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Reviewed-by: Paul Turner <pjt@google.com>
Reported-by: Aaron Jacobs <jacobsa@google.com>
Signed-off-by: Andrew Hunter <ahh@google.com>
[jstultz: Tweaked to apply to 3.17-rc]
Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-09-12 13:59:03 -07:00
Thomas Gleixner 13c42c2f43 futex: Unlock hb->lock in futex_wait_requeue_pi() error path
futex_wait_requeue_pi() calls futex_wait_setup(). If
futex_wait_setup() succeeds it returns with hb->lock held and
preemption disabled. Now the sanity check after this does:

        if (match_futex(&q.key, &key2)) {
	   	ret = -EINVAL;
		goto out_put_keys;
	}

which releases the keys but does not release hb->lock.

So we happily return to user space with hb->lock held and therefor
preemption disabled.

Unlock hb->lock before taking the exit route.

Reported-by: Dave "Trinity" Jones <davej@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Darren Hart <dvhart@linux.intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1409112318500.4178@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-09-12 22:04:36 +02:00
Rasmus Villemoes acbbe6fbb2 kcmp: fix standard comparison bug
The C operator <= defines a perfectly fine total ordering on the set of
values representable in a long.  However, unlike its namesake in the
integers, it is not translation invariant, meaning that we do not have
"b <= c" iff "a+b <= a+c" for all a,b,c.

This means that it is always wrong to try to boil down the relationship
between two longs to a question about the sign of their difference,
because the resulting relation [a LEQ b iff a-b <= 0] is neither
anti-symmetric or transitive.  The former is due to -LONG_MIN==LONG_MIN
(take any two a,b with a-b = LONG_MIN; then a LEQ b and b LEQ a, but a !=
b).  The latter can either be seen observing that x LEQ x+1 for all x,
implying x LEQ x+1 LEQ x+2 ...  LEQ x-1 LEQ x; or more directly with the
simple example a=LONG_MIN, b=0, c=1, for which a-b < 0, b-c < 0, but a-c >
0.

Note that it makes absolutely no difference that a transmogrying bijection
has been applied before the comparison is done.  In fact, had the
obfuscation not been done, one could probably not observe the bug
(assuming all values being compared always lie in one half of the address
space, the mathematical value of a-b is always representable in a long).
As it stands, one can easily obtain three file descriptors exhibiting the
non-transitivity of kcmp().

Side note 1: I can't see that ensuring the MSB of the multiplier is
set serves any purpose other than obfuscating the obfuscating code.

Side note 2:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>
#include <sys/syscall.h>

enum kcmp_type {
        KCMP_FILE,
        KCMP_VM,
        KCMP_FILES,
        KCMP_FS,
        KCMP_SIGHAND,
        KCMP_IO,
        KCMP_SYSVSEM,
        KCMP_TYPES,
};
pid_t pid;

int kcmp(pid_t pid1, pid_t pid2, int type,
	 unsigned long idx1, unsigned long idx2)
{
	return syscall(SYS_kcmp, pid1, pid2, type, idx1, idx2);
}
int cmp_fd(int fd1, int fd2)
{
	int c = kcmp(pid, pid, KCMP_FILE, fd1, fd2);
	if (c < 0) {
		perror("kcmp");
		exit(1);
	}
	assert(0 <= c && c < 3);
	return c;
}
int cmp_fdp(const void *a, const void *b)
{
	static const int normalize[] = {0, -1, 1};
	return normalize[cmp_fd(*(int*)a, *(int*)b)];
}
#define MAX 100 /* This is plenty; I've seen it trigger for MAX==3 */
int main(int argc, char *argv[])
{
	int r, s, count = 0;
	int REL[3] = {0,0,0};
	int fd[MAX];
	pid = getpid();
	while (count < MAX) {
		r = open("/dev/null", O_RDONLY);
		if (r < 0)
			break;
		fd[count++] = r;
	}
	printf("opened %d file descriptors\n", count);
	for (r = 0; r < count; ++r) {
		for (s = r+1; s < count; ++s) {
			REL[cmp_fd(fd[r], fd[s])]++;
		}
	}
	printf("== %d\t< %d\t> %d\n", REL[0], REL[1], REL[2]);
	qsort(fd, count, sizeof(fd[0]), cmp_fdp);
	memset(REL, 0, sizeof(REL));

	for (r = 0; r < count; ++r) {
		for (s = r+1; s < count; ++s) {
			REL[cmp_fd(fd[r], fd[s])]++;
		}
	}
	printf("== %d\t< %d\t> %d\n", REL[0], REL[1], REL[2]);
	return (REL[0] + REL[2] != 0);
}

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
"Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-10 15:42:12 -07:00
Patrick Palka 000a7d66ec kernel/printk/printk.c: fix faulty logic in the case of recursive printk
We shouldn't set text_len in the code path that detects printk recursion
because text_len corresponds to the length of the string inside textbuf.
A few lines down from the line

    text_len = strlen(recursion_msg);

is the line

    text_len += vscnprintf(text + text_len, ...);

So if printk detects recursion, it sets text_len to 29 (the length of
recursion_msg) and logs an error.  Then the message supplied by the
caller of printk is stored inside textbuf but offset by 29 bytes.  This
means that the output of the recursive call to printk will contain 29
bytes of garbage in front of it.

This defect is caused by commit 458df9fd48 ("printk: remove separate
printk_sched buffers and use printk buf instead") which turned the line

    text_len = vscnprintf(text, ...);

into

    text_len += vscnprintf(text + text_len, ...);

To fix this, this patch avoids setting text_len when logging the printk
recursion error.  This patch also marks unlikely() the branch leading up
to this code.

Fixes: 458df9fd48 ("printk: remove separate printk_sched buffers and use printk buf instead")
Signed-off-by: Patrick Palka <patrick@parcs.ath.cx>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-10 15:42:12 -07:00
Daniel Borkmann b954d83421 net: bpf: only build bpf_jit_binary_{alloc, free}() when jit selected
Since BPF JIT depends on the availability of module_alloc() and
module_free() helpers (HAVE_BPF_JIT and MODULES), we better build
that code only in case we have BPF_JIT in our config enabled, just
like with other JIT code. Fixes builds for arm/marzen_defconfig
and sh/rsk7269_defconfig.

====================
kernel/built-in.o: In function `bpf_jit_binary_alloc':
/home/cwang/linux/kernel/bpf/core.c:144: undefined reference to `module_alloc'
kernel/built-in.o: In function `bpf_jit_binary_free':
/home/cwang/linux/kernel/bpf/core.c:164: undefined reference to `module_free'
make: *** [vmlinux] Error 1
====================

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Fixes: 738cbe72ad ("net: bpf: consolidate JIT binary allocator")
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-10 14:05:07 -07:00
Andreea-Cristina Bernat fb5a613b4f kernel: trace_syscalls: Replace rcu_assign_pointer() with RCU_INIT_POINTER()
The uses of "rcu_assign_pointer()" are NULLing out the pointers.
According to RCU_INIT_POINTER()'s block comment:
"1.   This use of RCU_INIT_POINTER() is NULLing out the pointer"
it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.

The following Coccinelle semantic patch was used:
@@
@@

- rcu_assign_pointer
+ RCU_INIT_POINTER
  (..., NULL)

Link: http://lkml.kernel.org/p/20140822142822.GA32391@ada

Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-10 10:48:47 -04:00
Steven Rostedt (Red Hat) fef5aeeee9 ftrace: Replace tramp_hash with old_*_hash to save space
Allowing function callbacks to declare their own trampolines requires
that each ftrace_ops that has a trampoline must have some sort of
accounting that keeps track of which ops has a trampoline attached
to a record.

The easy way to solve this was to add a "tramp_hash" that created a
hash entry for every function that a ops uses with a trampoline.
But since we can have literally tens of thousands of functions being
traced, that means we need tens of thousands of descriptors to map
the ops to the function in the hash. This is quite expensive and
can cause enabling and disabling the function graph tracer to take
some time to start and stop. It can take up to several seconds to
disable or enable all functions in the function graph tracer for this
reason.

The better approach albeit more complex, is to keep track of how ops
are being enabled and disabled, and use that along with the counting
of the number of ops attached to records, to determive what ops has
a trampoline attached to a record at enabling and disabling of
tracing.

To do this, the tramp_hash has been replaced with an old_filter_hash
and old_notrace_hash, which get the copy of the ops filter_hash and
notrace_hash respectively. The old hashes is kept until the ops has
been modified or removed and the old hashes are used with the logic
of the accounting to determine the ops that have the trampoline of
a record. The reason this has less of a footprint is due to the trick
that an "empty" hash in the filter_hash means "all functions" and
an empty hash in the notrace hash means "no functions" in the hash.

This is much more efficienct, doesn't have the delay, and takes up
much less memory, as we do not need to map all the functions but
just figure out which functions are mapped at the time it is
enabled or disabled.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-10 10:48:45 -04:00
Steven Rostedt (Red Hat) e1effa0144 ftrace: Annotate the ops operation on update
Add three new flags for ftrace_ops:

  FTRACE_OPS_FL_ADDING
  FTRACE_OPS_FL_REMOVING
  FTRACE_OPS_FL_MODIFYING

These will be set for the ftrace_ops when they are first added
to the function tracing, being removed from function tracing
or just having their functions changed from function tracing,
respectively.

This will be needed to remove the tramp_hash, which can grow quite
big. The tramp_hash is used to note what functions a ftrace_ops
is using a trampoline for. Denoting which ftrace_ops is being
modified, will allow us to use the ftrace_ops hashes themselves,
which are much smaller as they have a global flag to denote if
a ftrace_ops is tracing all functions, as well as a notrace hash
if the ftrace_ops is tracing all but a few. The tramp_hash just
creates a hash item for every function, which can go into the 10s
of thousands if all functions are using the ftrace_ops trampoline.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-10 10:48:44 -04:00
Steven Rostedt (Red Hat) 5fecaa044a ftrace: Grab any ops for a rec for enabled_functions output
When dumping the enabled_functions, use the first op that is
found with a trampoline to the record, as there should only be
one, as only one ops can be registered to a function that has
a trampoline.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-10 10:48:43 -04:00
Steven Rostedt (Red Hat) 3296fc4e25 ftrace: Remove freeing of old_hash from ftrace_hash_move()
ftrace_hash_move() currently frees the old hash that is passed to it
after replacing the pointer with the new hash. Instead of having the
function do that chore, have the caller perform the free.

This lets the ftrace_hash_move() be used a bit more freely, which
is needed for changing the way the trampoline logic is done.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-10 10:48:42 -04:00
Steven Rostedt (Red Hat) f7aad4e1a8 ftrace: Set callback to ftrace_stub when no ops are registered
The clean up that adds the helper function ftrace_ops_get_func()
caused the default function to not change when DYNAMIC_FTRACE was not
set and no ftrace_ops were registered. Although static tracing is
not very useful (not having DYNAMIC_FTRACE set), it is still supported
and we don't want to break it.

Clean up the if statement even more to specifically have the default
function call ftrace_stub when no ftrace_ops are registered. This
fixes the small bug for static tracing as well as makes the code a
bit more understandable.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-10 10:48:18 -04:00
Daniel Borkmann 738cbe72ad net: bpf: consolidate JIT binary allocator
Introduced in commit 314beb9bca ("x86: bpf_jit_comp: secure bpf jit
against spraying attacks") and later on replicated in aa2d2c73c2
("s390/bpf,jit: address randomize and write protect jit code") for
s390 architecture, write protection for BPF JIT images got added and
a random start address of the JIT code, so that it's not on a page
boundary anymore.

Since both use a very similar allocator for the BPF binary header,
we can consolidate this code into the BPF core as it's mostly JIT
independant anyway.

This will also allow for future archs that support DEBUG_SET_MODULE_RONX
to just reuse instead of reimplementing it.

JIT tested on x86_64 and s390x with BPF test suite.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-09 16:58:56 -07:00
Steven Rostedt (Red Hat) 8735405988 ftrace: Add helper function ftrace_ops_get_func()
Add the helper function to what the mcount trampoline is to call
for a ftrace_ops function. This helper will be used by arch code
in the future to set up dynamic trampolines. But as this does the
same tests that are performed in choosing what function to call for
the default mcount trampoline, might as well use it to clean up
the existing code.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-09 19:26:06 -04:00
Alexei Starovoitov 02ab695bb3 net: filter: add "load 64-bit immediate" eBPF instruction
add BPF_LD_IMM64 instruction to load 64-bit immediate value into a register.
All previous instructions were 8-byte. This is first 16-byte instruction.
Two consecutive 'struct bpf_insn' blocks are interpreted as single instruction:
insn[0].code = BPF_LD | BPF_DW | BPF_IMM
insn[0].dst_reg = destination register
insn[0].imm = lower 32-bit
insn[1].code = 0
insn[1].imm = upper 32-bit
All unused fields must be zero.

Classic BPF has similar instruction: BPF_LD | BPF_W | BPF_IMM
which loads 32-bit immediate value into a register.

x64 JITs it as single 'movabsq %rax, imm64'
arm64 may JIT as sequence of four 'movk x0, #imm16, lsl #shift' insn

Note that old eBPF programs are binary compatible with new interpreter.

It helps eBPF programs load 64-bit constant into a register with one
instruction instead of using two registers and 4 instructions:
BPF_MOV32_IMM(R1, imm32)
BPF_ALU64_IMM(BPF_LSH, R1, 32)
BPF_MOV32_IMM(R2, imm32)
BPF_ALU64_REG(BPF_OR, R1, R2)

User space generated programs will use this instruction to load constants only.

To tell kernel that user space needs a pointer the _pseudo_ variant of
this instruction may be added later, which will use extra bits of encoding
to indicate what type of pointer user space is asking kernel to provide.
For example 'off' or 'src_reg' fields can be used for such purpose.
src_reg = 1 could mean that user space is asking kernel to validate and
load in-kernel map pointer.
src_reg = 2 could mean that user space needs readonly data section pointer
src_reg = 3 could mean that user space needs a pointer to per-cpu local data
All such future pseudo instructions will not be carrying the actual pointer
as part of the instruction, but rather will be treated as a request to kernel
to provide one. The kernel will verify the request_for_a_pointer, then
will drop _pseudo_ marking and will store actual internal pointer inside
the instruction, so the end result is the interpreter and JITs never
see pseudo BPF_LD_IMM64 insns and only operate on generic BPF_LD_IMM64 that
loads 64-bit immediate into a register. User space never operates on direct
pointers and verifier can easily recognize request_for_pointer vs other
instructions.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-09 10:26:47 -07:00
Steven Rostedt (Red Hat) f1ff6348b3 ftrace: Add separate function for non recursive callbacks
Instead of using the generic list function for callbacks that
are not recursive, call a new helper function from the mcount
trampoline called ftrace_ops_recur_func() that will do the recursion
checking for the callback.

This eliminates an indirection as well as will help in future code
that will use dynamically allocated trampolines.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-09-09 10:26:48 -04:00
Masanari Iida da3dae54e4 Documentation: Docbook: Fix generated DocBook/kernel-api.xml
This patch fix spelling typo found in DocBook/kernel-api.xml.
It is because the file is generated from the source comments,
I have to fix the comments in source codes.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2014-09-09 10:34:56 +02:00
Cong Wang 3577af70a2 perf: Fix a race condition in perf_remove_from_context()
We saw a kernel soft lockup in perf_remove_from_context(),
it looks like the `perf` process, when exiting, could not go
out of the retry loop. Meanwhile, the target process was forking
a child. So either the target process should execute the smp
function call to deactive the event (if it was running) or it should
do a context switch which deactives the event.

It seems we optimize out a context switch in perf_event_context_sched_out(),
and what's more important, we still test an obsolete task pointer when
retrying, so no one actually would deactive that event in this situation.
Fix it directly by reloading the task pointer in perf_remove_from_context().

This should cure the above soft lockup.

Signed-off-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1409696840-843-1-git-send-email-xiyou.wangcong@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-09 06:53:42 +02:00
Andreea-Cristina Bernat 70691d4a0b perf/core: Replace rcu_assign_pointer() with RCU_INIT_POINTER()
The use of "rcu_assign_pointer()" is NULLing out the pointer.
According to RCU_INIT_POINTER()'s block comment:

  "1.   This use of RCU_INIT_POINTER() is NULLing out the pointer"

it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.

The following Coccinelle semantic patch was used:
  @@
  @@

  - rcu_assign_pointer
  + RCU_INIT_POINTER
    (..., NULL)

Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: http://lkml.kernel.org/r/20140822132605.GA20130@ada
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-09 06:53:05 +02:00
Andreea-Cristina Bernat e0455e194a perf/callchain: Replace rcu_assign_pointer() with RCU_INIT_POINTER()
The use of "rcu_assign_pointer()" is NULLing out the pointer.
According to RCU_INIT_POINTER()'s block comment:

 "1.   This use of RCU_INIT_POINTER() is NULLing out the pointer"

it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.

 The following Coccinelle semantic patch was used:
 @@
 @@

 - rcu_assign_pointer
 + RCU_INIT_POINTER
   (..., NULL)

Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: paulmck@linux.vnet.ibm.com
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: http://lkml.kernel.org/r/20140822141536.GA32051@ada
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-09 06:53:04 +02:00
Ingo Molnar bdea534db8 Linux 3.17-rc4
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Merge tag 'v3.17-rc4' into perf/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-09 06:48:07 +02:00
Jason Low 8236d907ab sched: Reduce contention in update_cfs_rq_blocked_load()
When running workloads on 2+ socket systems, based on perf profiles, the
update_cfs_rq_blocked_load() function often shows up as taking up a
noticeable % of run time.

Much of the contention is in __update_cfs_rq_tg_load_contrib() when we
update the tg load contribution stats.  However, it turns out that in many
cases, they don't need to be updated and "tg_contrib" is 0.

This patch adds a check in __update_cfs_rq_tg_load_contrib() to skip updating
tg load contribution stats when nothing needs to be updated. This reduces the
cacheline contention that would be unnecessary.

Reviewed-by: Ben Segall <bsegall@google.com>
Reviewed-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: jason.low2@hp.com
Cc: Yuyang Du <yuyang.du@intel.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Chegu Vinod <chegu_vinod@hp.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409643684.19197.15.camel@j-VirtualBox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-09 06:47:29 +02:00
Lai Jiangshan 5cd038f53e sched: Migrate waking tasks
Current code can fail to migrate a waking task (silently) when TTWU_QUEUE is
enabled.

When a task is waking, it is pending on the wake_list of the rq, but it is not
queued (task->on_rq == 0). In this case, set_cpus_allowed_ptr() and
__migrate_task() will not migrate it because its invisible to them.

This behavior is incorrect, because the task has been already woken, it will be
running on the wrong CPU without correct placement until the next wake-up or
update for cpus_allowed.

To fix this problem, we need to finish the wakeup (so they appear on
the runqueue) before we migrate them.

Reported-by: Sasha Levin <sasha.levin@oracle.com>
Reported-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Tested-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/538ED7EB.5050303@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-09 06:47:27 +02:00
Srinivas Pandruvada 2ce986892f PM / sleep: Enhance test_suspend option with repeat capability
Enhanced test_suspend boot paramter to repeat tests multiple times,
by adding optional repeat count. The new boot param syntax:
test_suspend="mem|freeze|standby[,N]"

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-09 01:48:02 +02:00
Srinivas Pandruvada bc7115b144 PM / sleep: Support freeze as test_suspend option
Added freeze as one of the option for test_suspend boot param.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-09 01:48:01 +02:00
Rik van Riel eb1b4af0a6 sched, time: Atomically increment stime & utime
The functions task_cputime_adjusted and thread_group_cputime_adjusted()
can be called locklessly, as well as concurrently on many different CPUs.

This can occasionally lead to the utime and stime reported by times(), and
other syscalls like it, going backward. The cause for this appears to be
multiple threads racing in cputime_adjust(), both with values for utime or
stime that is larger than the original, but each with a different value.

Sometimes the larger value gets saved first, only to be immediately
overwritten with a smaller value by another thread.

Using atomic exchange prevents that problem, and ensures time
progresses monotonically.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: umgwanakikbuti@gmail.com
Cc: fweisbec@gmail.com
Cc: akpm@linux-foundation.org
Cc: srao@redhat.com
Cc: lwoodman@redhat.com
Cc: atheurer@redhat.com
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/1408133138-22048-4-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-08 08:17:02 +02:00
Rik van Riel e78c349679 time, signal: Protect resource use statistics with seqlock
Both times() and clock_gettime(CLOCK_PROCESS_CPUTIME_ID) have scalability
issues on large systems, due to both functions being serialized with a
lock.

The lock protects against reporting a wrong value, due to a thread in the
task group exiting, its statistics reporting up to the signal struct, and
that exited task's statistics being counted twice (or not at all).

Protecting that with a lock results in times() and clock_gettime() being
completely serialized on large systems.

This can be fixed by using a seqlock around the events that gather and
propagate statistics. As an additional benefit, the protection code can
be moved into thread_group_cputime(), slightly simplifying the calling
functions.

In the case of posix_cpu_clock_get_task() things can be simplified a
lot, because the calling function already ensures that the task sticks
around, and the rest is now taken care of in thread_group_cputime().

This way the statistics reporting code can run lockless.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Daeseok Youn <daeseok.youn@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guillaume Morin <guillaume@morinfr.org>
Cc: Ionut Alexa <ionut.m.alexa@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Michal Schmidt <mschmidt@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: umgwanakikbuti@gmail.com
Cc: fweisbec@gmail.com
Cc: srao@redhat.com
Cc: lwoodman@redhat.com
Cc: atheurer@redhat.com
Link: http://lkml.kernel.org/r/20140816134010.26a9b572@annuminas.surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-08 08:17:01 +02:00
Rik van Riel 90ed9cbe76 exit: Always reap resource stats in __exit_signal()
Oleg pointed out that wait_task_zombie adds a task's usage statistics
to the parent's signal struct, but the task's own signal struct should
also propagate the statistics at exit time.

This allows thread_group_cputime(reaped_zombie) to get the statistics
after __unhash_process() has made the task invisible to for_each_thread,
but before the thread has actually been rcu freed, making sure no
non-monotonic results are returned inside that window.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Guillaume Morin <guillaume@morinfr.org>
Cc: Ionut Alexa <ionut.m.alexa@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Michal Schmidt <mschmidt@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: umgwanakikbuti@gmail.com
Cc: fweisbec@gmail.com
Cc: srao@redhat.com
Cc: lwoodman@redhat.com
Cc: atheurer@redhat.com
Link: http://lkml.kernel.org/r/1408133138-22048-2-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-08 08:17:00 +02:00
Ingo Molnar e2627dce26 Linux 3.17-rc4
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Merge tag 'v3.17-rc4' into sched/core, to prevent conflicts with upcoming patches, and to refresh the tree

Linux 3.17-rc4
2014-09-08 08:11:34 +02:00
David S. Miller eb84d6b604 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2014-09-07 21:41:53 -07:00
Linus Torvalds d030671f3f Merge branch 'for-3.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
 "This pull request includes Alban's patch to disallow '\n' in cgroup
  names.

  Two other patches from Li to fix a possible oops when cgroup
  destruction races against other file operations and one from Vivek to
  fix a unified hierarchy devel behavior"

* 'for-3.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: check cgroup liveliness before unbreaking kernfs
  cgroup: delay the clearing of cgrp->kn->priv
  cgroup: Display legacy cgroup files on default hierarchy
  cgroup: reject cgroup names with '\n'
2014-09-07 20:20:16 -07:00
Tejun Heo a34375ef9e percpu-refcount: add @gfp to percpu_ref_init()
Percpu allocator now supports allocation mask.  Add @gfp to
percpu_ref_init() so that !GFP_KERNEL allocation masks can be used
with percpu_refs too.

This patch doesn't make any functional difference.

v2: blk-mq conversion was missing.  Updated.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Nicholas A. Bellinger <nab@linux-iscsi.org>
Cc: Jens Axboe <axboe@kernel.dk>
2014-09-08 09:51:30 +09:00
Paul E. McKenney 284a8c93af rcu: Per-CPU operation cleanups to rcu_*_qs() functions
The rcu_bh_qs(), rcu_preempt_qs(), and rcu_sched_qs() functions use
old-style per-CPU variable access and write to ->passed_quiesce even
if it is already set.  This commit therefore updates to use the new-style
per-CPU variable access functions and avoids the spurious writes.
This commit also eliminates the "cpu" argument to these functions because
they are always invoked on the indicated CPU.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:35 -07:00
Paul E. McKenney 1d082fd061 rcu: Remove local_irq_disable() in rcu_preempt_note_context_switch()
The rcu_preempt_note_context_switch() function is on a scheduling fast
path, so it would be good to avoid disabling irqs.  The reason that irqs
are disabled is to synchronize process-level and irq-handler access to
the task_struct ->rcu_read_unlock_special bitmask.  This commit therefore
makes ->rcu_read_unlock_special instead be a union of bools with a short
allowing single-access checks in RCU's __rcu_read_unlock().  This results
in the process-level and irq-handler accesses being simple loads and
stores, so that irqs need no longer be disabled.  This commit therefore
removes the irq disabling from rcu_preempt_note_context_switch().

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:34 -07:00
Paul E. McKenney 4ff475ed4c rcu: Additional information on RCU-tasks stall-warning messages
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:33 -07:00
Paul E. McKenney 8f20a5e83d rcu: Make rcu_tasks_kthread()'s GP-wait loop allow preemption
The grace-period-wait loop in rcu_tasks_kthread() is under (unnecessary)
RCU protection, and therefore has no preemption points in a PREEMPT=n
kernel.  This commit therefore removes the RCU protection and inserts
cond_resched().

Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:31 -07:00
Paul E. McKenney 176f8f7a52 rcu: Make TASKS_RCU handle nohz_full= CPUs
Currently TASKS_RCU would ignore a CPU running a task in nohz_full=
usermode execution.  There would be neither a context switch nor a
scheduling-clock interrupt to tell TASKS_RCU that the task in question
had passed through a quiescent state.  The grace period would therefore
extend indefinitely.  This commit therefore makes RCU's dyntick-idle
subsystem record the task_struct structure of the task that is running
in dyntick-idle mode on each CPU.  The TASKS_RCU grace period can
then access this information and record a quiescent state on
behalf of any CPU running in dyntick-idle usermode.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:30 -07:00
Paul E. McKenney 84a8f446ff rcu: Defer rcu_tasks_kthread() creation till first call_rcu_tasks()
It is expected that many sites will have CONFIG_TASKS_RCU=y, but
will never actually invoke call_rcu_tasks().  For such sites, creating
rcu_tasks_kthread() at boot is wasteful.  This commit therefore defers
creation of this kthread until the time of the first call_rcu_tasks().

This of course means that the first call_rcu_tasks() must be invoked
from process context after the scheduler is fully operational.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:29 -07:00
Paul E. McKenney c7b24d2b9a rcu: Improve RCU-tasks energy efficiency
The current RCU-tasks implementation uses strict polling to detect
callback arrivals.  This works quite well, but is not so good for
energy efficiency.  This commit therefore replaces the strict polling
with a wait queue.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:27 -07:00
Paul E. McKenney 52db30ab23 rcu: Add stall-warning checks for RCU-tasks
This commit adds a ten-minute RCU-tasks stall warning.  The actual
time is controlled by the boot/sysfs parameter rcu_task_stall_timeout,
with values less than or equal to zero disabling the stall warnings.
The default value is ten minutes, which means that the tasks that have
not yet responded will get their stacks dumped every ten minutes, until
they pass through a voluntary context switch.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:26 -07:00
Paul E. McKenney 69c604557c rcutorture: Add torture tests for RCU-tasks
This commit adds torture tests for RCU-tasks.  It also fixes a bug that
would segfault for an RCU flavor lacking a callback-barrier function.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-09-07 16:27:24 -07:00
Steven Rostedt 06c2a9238f rcu: Export RCU-tasks APIs to GPL modules
This commit exports the RCU-tasks synchronous APIs,
synchronize_rcu_tasks() and rcu_barrier_tasks(), to
GPL-licensed kernel modules.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-09-07 16:27:23 -07:00
Paul E. McKenney 3f95aa81d2 rcu: Make TASKS_RCU handle tasks that are almost done exiting
Once a task has passed exit_notify() in the do_exit() code path, it
is no longer on the task lists, and is therefore no longer visible
to rcu_tasks_kthread().  This means that an almost-exited task might
be preempted while within a trampoline, and this task won't be waited
on by rcu_tasks_kthread().  This commit fixes this bug by adding an
srcu_struct.  An exiting task does srcu_read_lock() just before calling
exit_notify(), and does the corresponding srcu_read_unlock() after
doing the final preempt_disable().  This means that rcu_tasks_kthread()
can do synchronize_srcu() to wait for all mostly-exited tasks to reach
their final preempt_disable() region, and then use synchronize_sched()
to wait for those tasks to finish exiting.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:22 -07:00
Paul E. McKenney 53c6d4edf8 rcu: Add synchronous grace-period waiting for RCU-tasks
It turns out to be easier to add the synchronous grace-period waiting
functions to RCU-tasks than to work around their absense in rcutorture,
so this commit adds them.  The key point is that the existence of
call_rcu_tasks() means that rcutorture needs an rcu_barrier_tasks().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:21 -07:00
Paul E. McKenney bde6c3aa99 rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loops
RCU-tasks requires the occasional voluntary context switch
from CPU-bound in-kernel tasks.  In some cases, this requires
instrumenting cond_resched().  However, there is some reluctance
to countenance unconditionally instrumenting cond_resched() (see
http://lwn.net/Articles/603252/), so this commit creates a separate
cond_resched_rcu_qs() that may be used in place of cond_resched() in
locations prone to long-duration in-kernel looping.

This commit currently instruments only RCU-tasks.  Future possibilities
include also instrumenting RCU, RCU-bh, and RCU-sched in order to reduce
IPI usage.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:20 -07:00
Paul E. McKenney 8315f42295 rcu: Add call_rcu_tasks()
This commit adds a new RCU-tasks flavor of RCU, which provides
call_rcu_tasks().  This RCU flavor's quiescent states are voluntary
context switch (not preemption!) and userspace execution (not the idle
loop -- use some sort of schedule_on_each_cpu() if you need to handle the
idle tasks.  Note that unlike other RCU flavors, these quiescent states
occur in tasks, not necessarily CPUs.  Includes fixes from Steven Rostedt.

This RCU flavor is assumed to have very infrequent latency-tolerant
updaters.  This assumption permits significant simplifications, including
a single global callback list protected by a single global lock, along
with a single task-private linked list containing all tasks that have not
yet passed through a quiescent state.  If experience shows this assumption
to be incorrect, the required additional complexity will be added.

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:27:19 -07:00
Paul E. McKenney 38706bc5a2 rcutorture: Add callback-flood test
Although RCU is designed to handle arbitrary floods of callbacks, this
capability is not routinely tested.   This commit therefore adds a
cbflood capability in which kthreads repeatedly registers large numbers
of callbacks.  One such kthread is created for each four CPUs (rounding
up), and the test may be controlled by several cbflood_* kernel boot
parameters, which control the number of bursts per flood, the number
of callbacks per burst, the time between bursts, and the time between
floods.  The default values are large enough to exercise RCU's emergency
responses to callback flooding.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: David Miller <davem@davemloft.net>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
2014-09-07 16:24:48 -07:00
Joe Perches eea203fea3 rcu: Use pr_alert/pr_cont for printing logs
User pr_alert/pr_cont for printing the logs from rcutorture module directly
instead of writing it to a buffer and then printing it. This allows us from not
having to allocate such buffers. Also remove a resulting empty function.

I tested this using the parse-torture.sh script as follows:

$ dmesg | grep torture > log.txt
$ bash parse-torture.sh log.txt test
$

There were no warnings which means that parsing went fine.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:24:47 -07:00
Pranith Kumar 58ade2dbe9 rcutorture: Fix a sparse warning by marking boost_mutex static
This commit fixes the following sparse warning by marking boost_mutex
static:

kernel/rcu/rcutorture.c:185:1: warning: symbol 'boost_mutex' was not declared. Should it be static?

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-09-07 16:24:17 -07:00
Paul E. McKenney 73a860cd58 rcu: Replace flush_signals() with WARN_ON(signal_pending())
Currently, when RCU awakens from a wait_event_interruptible() that
might have awakened prematurely, it does a flush_signals(). This is
done on the off-chance that someone figured out how to deliver a signal
to a kthread, which is supposed to be impossible.  Given that this
is supposed to be impossible, this commit changes the flush_signals()
calls into WARN_ON(signal_pending()).

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:20 -07:00
Pranith Kumar 2aa792e6fa rcu: Use rcu_gp_kthread_wake() to wake up grace period kthreads
The rcu_gp_kthread_wake() function checks for three conditions before
waking up grace period kthreads:

*  Is the thread we are trying to wake up the current thread?
*  Are the gp_flags zero? (all threads wait on non-zero gp_flags condition)
*  Is there no thread created for this flavour, hence nothing to wake up?

If any one of these condition is true, we do not call wake_up().
It was found that there are quite a few avoidable wake ups both during
idle time and under stress induced by rcutorture.

Idle:

Total:66000, unnecessary:66000, case1:61827, case2:66000, case3:0
Total:68000, unnecessary:68000, case1:63696, case2:68000, case3:0

rcutorture:

Total:254000, unnecessary:254000, case1:199913, case2:254000, case3:0
Total:256000, unnecessary:256000, case1:201784, case2:256000, case3:0

Here case{1-3} are the cases listed above. We can avoid these wake
ups by using rcu_gp_kthread_wake() to conditionally wake up the grace
period kthreads.

There is a comment about an implied barrier supplied by the wake_up()
logic.  This barrier is necessary for the awakened thread to see the
updated ->gp_flags.  This flag is always being updated with the root node
lock held. Also, the awakened thread tries to acquire the root node lock
before reading ->gp_flags because of which there is proper ordering.

Hence this commit tries to avoid calling wake_up() whenever we can by
using rcu_gp_kthread_wake() function.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
CC: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:19 -07:00
Paul E. McKenney ade9862470 rcu: Make TINY_RCU tinier by putting error checks under #ifdef
The rcu_idle_enter_common() and rcu_idle_exit_common() functions contain
error checks that have to the best of my knowledge have never triggered
over the past several years.  These are nevertheless valuable when
creating new architectures or doing other low-level changes, so the
checks should not be deleted.  This commit instead places these checks
under #ifdef CONFIG_RCU_TRACE so that they are executed only when
specifically requested.

The savings are significant:

	Before:

	   text    data     bss     dec     hex filename
	   1749      39       0    1788     6fc /tmp/b/kernel/rcu/tiny.o
	    632     152       0     784     310 /tmp/b/kernel/rcu/update.o
				   ----
				   2572

	After:

	   text    data     bss     dec     hex filename
	   1281      37       0    1318     526 /tmp/b/kernel/rcu/tiny.o
	    632     152       0     784     310 /tmp/b/kernel/rcu/update.o
				   ----
				   2102

This amounts to 470 bytes, or 18% of the original.

Switched from #ifdef to IS_ENABLED() on Josh Triplett's advice.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2014-09-07 16:18:18 -07:00
Paul E. McKenney 9fdd3bc900 rcu: Break more call_rcu() deadlock involving scheduler and perf
Commit 96d3fd0d31 (rcu: Break call_rcu() deadlock involving scheduler
and perf) covered the case where __call_rcu_nocb_enqueue() needs to wake
the rcuo kthread due to the queue being initially empty, but did not
do anything for the case where the queue was overflowing.  This commit
therefore also defers wakeup for the overflow case.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:17 -07:00
Pranith Kumar 66d701ea7e rcu: Remove stale comment in tree.c
This commit removes a stale comment in rcu/tree.c which was left
out when some code was moved around previously in commit 2036d94a7b
("rcu:  Rework detection of use of RCU by offline CPUs") For reference,
the following updated comment exists a few lines below this which means
the same:

/* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:16 -07:00
Pranith Kumar fafb6e843f rcu: Update tiny.c references to tree.c
This commit updates the references to rcutree.c which is now rcu/tree.c

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:15 -07:00
Ard Biesheuvel a8a29b3b7b rcu: Define tracepoint strings only if CONFIG_TRACING is set
Commit f7f7bac9cb ("rcu: Have the RCU tracepoints use the tracepoint_string
infrastructure") unconditionally populates the __tracepoint_str input section,
but this section is not assigned an output section if CONFIG_TRACING is not set.
This results in the __tracepoint_str turning up in unexpected places, i.e.,
after _edata.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:14 -07:00
Oleg Nesterov 85b39d305b rcu: Uninline rcu_read_lock_held()
This commit uninlines rcu_read_lock_held(). According to "size vmlinux"
this saves 28549 in .text:

	- 5541731 3014560 14757888 23314179
	+ 5513182 3026848 14757888 23297918

Note: it looks as if the data grows by 12288 bytes but this is not true,
it does not actually grow. But .data starts with ALIGN(THREAD_SIZE) and
since .text shrinks the padding grows, and thus .data grows too as it
seen by /bin/size. diff System.map:

	- ffffffff81510000 D _sdata
	- ffffffff81510000 D init_thread_union
	+ ffffffff81509000 D _sdata
	+ ffffffff8150c000 D init_thread_union

Perhaps we can change vmlinux.lds.S to .data itself, so that /bin/size
can't "wrongly" report that .data grows if .text shinks.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:13 -07:00
Pranith Kumar e02b2edfa1 rcu: Use true/false instead of 1/0 for a bool type
This commit uses true/false instead of 1/0 for bool types in rcu_gp_fqs()
and force_qs_rnp().

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:12 -07:00
Pranith Kumar d0bc90fd37 rcu: Return bool type for rcu_try_advance_all_cbs()
Return a bool type instead of 0 in rcu_try_advance_all_cbs().

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:10 -07:00
Pranith Kumar f534ed1fd7 rcu: Use bool type for return value in rcu_is_watching()
Use a bool type for return in rcu_is_watching().

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:09 -07:00
Pranith Kumar bf33eb1aef rcu: Fix sparse warning about rcu_batches_completed_preempt() being non-static
fix sparse warning about rcu_batches_completed_preempt() being non-static by
marking it as static

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:08 -07:00
Pranith Kumar 4de376a1b1 rcu: Remove remaining read-modify-write ACCESS_ONCE() calls
Change the remaining uses of ACCESS_ONCE() so that each ACCESS_ONCE() either does a load or a store, but not both.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2014-09-07 16:18:07 -07:00
Linus Torvalds 6fef37c9a7 ACPI and power management fixes for 3.17-rc4
- Fix for recently broken test_suspend= command line argument
    (Rafael J Wysocki).
 
  - Fixes for regressions related to the ACPI video driver caused
    by switching the default to native backlight handling in 3.16
    from Hans de Goede.
 
  - Fix for a sysfs attribute of ACPI device objects that returns
    stale values sometimes due to the fact that they are cached
    instead of executing the appropriate method (_SUN) every time
    (broken in 3.14).  From Yasuaki Ishimatsu.
 
  - Fix for a deadlock between cpuidle_lock and cpu_hotplug.lock
    in the ACPI processor driver from Jiri Kosina.
 
  - Runtime output validation for the ACPI _DSD device configuration
    object missing from the support for it that has been introduced
    recently.  From Mika Westerberg.
 
  - Fix for an unuseful and misleading RAPL (Running Average Power
    Limit) domain detection message in the RAPL driver from Jacob Pan.
 
  - New Intel Haswell CPU ID for the RAPL driver from Jason Baron.
 
  - New Clevo W350etq blacklist entry for the ACPI EC driver
    from Lan Tianyu.
 
  - Cleanup for the intel_pstate driver and the core generic PM
    domains code from Gabriele Mazzotta and Geert Uytterhoeven.
 
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Merge tag 'pm+acpi-3.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI and power management fixes from Rafael Wysocki:
 "These are regression fixes (ACPI sysfs, ACPI video, suspend test),
  ACPI cpuidle deadlock fix, missing runtime validation of ACPI _DSD
  output, a fix and a new CPU ID for the RAPL driver, new blacklist
  entry for the ACPI EC driver and a couple of trivial cleanups
  (intel_pstate and generic PM domains).

  Specifics:

   - Fix for recently broken test_suspend= command line argument (Rafael
     Wysocki).

   - Fixes for regressions related to the ACPI video driver caused by
     switching the default to native backlight handling in 3.16 from
     Hans de Goede.

   - Fix for a sysfs attribute of ACPI device objects that returns stale
     values sometimes due to the fact that they are cached instead of
     executing the appropriate method (_SUN) every time (broken in
     3.14).  From Yasuaki Ishimatsu.

   - Fix for a deadlock between cpuidle_lock and cpu_hotplug.lock in the
     ACPI processor driver from Jiri Kosina.

   - Runtime output validation for the ACPI _DSD device configuration
     object missing from the support for it that has been introduced
     recently.  From Mika Westerberg.

   - Fix for an unuseful and misleading RAPL (Running Average Power
     Limit) domain detection message in the RAPL driver from Jacob Pan.

   - New Intel Haswell CPU ID for the RAPL driver from Jason Baron.

   - New Clevo W350etq blacklist entry for the ACPI EC driver from Lan
     Tianyu.

   - Cleanup for the intel_pstate driver and the core generic PM domains
     code from Gabriele Mazzotta and Geert Uytterhoeven"

* tag 'pm+acpi-3.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / cpuidle: fix deadlock between cpuidle_lock and cpu_hotplug.lock
  ACPI / scan: not cache _SUN value in struct acpi_device_pnp
  cpufreq: intel_pstate: Remove unneeded variable
  powercap / RAPL: change domain detection message
  powercap / RAPL: add support for CPU model 0x3f
  PM / domains: Make generic_pm_domain.name const
  PM / sleep: Fix test_suspend= command line option
  ACPI / EC: Add msi quirk for Clevo W350etq
  ACPI / video: Disable native_backlight on HP ENVY 15 Notebook PC
  ACPI / video: Add a disable_native_backlight quirk
  ACPI / video: Fix use_native_backlight selection logic
  ACPICA: ACPI 5.1: Add support for runtime validation of _DSD package.
2014-09-07 11:57:27 -07:00
Linus Torvalds 81368f8bb8 Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU fix from Ingo Molnar:
 "A boot hang fix for the offloaded callback RCU model (RCU_NOCB_CPU=y
  && (TREE_CPU=y || TREE_PREEMPT_RC)) in certain bootup scenarios"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Make nocb leader kthreads process pending callbacks after spawning
2014-09-07 10:51:42 -07:00
Linus Torvalds ebc54f278f Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Thomas Gleixner:
 "Three fixlets from the timer departement:

   - Update the timekeeper before updating vsyscall and pvclock.  This
     fixes the kvm-clock regression reported by Chris and Paolo.

   - Use the proper irq work interface from NMI.  This fixes the
     regression reported by Catalin and Dave.

   - Clarify the compat_nanosleep error handling mechanism to avoid
     future confusion"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timekeeping: Update timekeeper before updating vsyscall and pvclock
  compat: nanosleep: Clarify error handling
  nohz: Restore NMI safe local irq work for local nohz kick
2014-09-07 10:37:48 -07:00
xiaofeng.yan 177ef2a631 sched/deadline: Fix a precision problem in the microseconds range
An overrun could happen in function start_hrtick_dl()
when a task with SCHED_DEADLINE runs in the microseconds
range.

For example, if a task with SCHED_DEADLINE has the following parameters:

  Task  runtime  deadline  period
   P1   200us     500us    500us

The deadline and period from task P1 are less than 1ms.

In order to achieve microsecond precision, we need to enable HRTICK feature
by the next command:

  PC#echo "HRTICK" > /sys/kernel/debug/sched_features
  PC#trace-cmd record -e sched_switch &
  PC#./schedtool -E -t 200000:500000:500000 -e ./test

The binary test is in an endless while(1) loop here.
Some pieces of trace.dat are as follows:

  <idle>-0   157.603157: sched_switch: :R ==> 2481:4294967295: test
  test-2481  157.603203: sched_switch:  2481:R ==> 0:120: swapper/2
  <idle>-0   157.605657: sched_switch:  :R ==> 2481:4294967295: test
  test-2481  157.608183: sched_switch:  2481:R ==> 2483:120: trace-cmd
  trace-cmd-2483 157.609656: sched_switch:2483:R==>2481:4294967295: test

We can get the runtime of P1 from the information above:

  runtime = 157.608183 - 157.605657
  runtime = 0.002526(2.526ms)

The correct runtime should be less than or equal to 200us at some point.

The problem is caused by a conditional judgment "delta > 10000"
in function start_hrtick_dl().

Because no hrtimer start up to control the rest of runtime
when the reset of runtime is less than 10us.

So the process will continue to run until tick-period is coming.

Move the code with the limit of the least time slice
from hrtick_start_fair() to hrtick_start() because the
EDF schedule class also needs this function in start_hrtick_dl().

To fix this problem, we call hrtimer_start() unconditionally in
start_hrtick_dl(), and make sure the scheduling slice won't be smaller
than 10us in hrtimer_start().

Signed-off-by: Xiaofeng Yan <xiaofeng.yan@huawei.com>
Reviewed-by: Li Zefan <lizefan@huawei.com>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409022941-5880-1-git-send-email-xiaofeng.yan@huawei.com
[ Massaged the changelog and the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-07 11:09:59 +02:00
Thomas Gleixner 9bf2419fa7 timekeeping: Update timekeeper before updating vsyscall and pvclock
The update_walltime() code works on the shadow timekeeper to make the
seqcount protected region as short as possible. But that update to the
shadow timekeeper does not update all timekeeper fields because it's
sufficient to do that once before it becomes life. One of these fields
is tkr.base_mono. That stays stale in the shadow timekeeper unless an
operation happens which copies the real timekeeper to the shadow.

The update function is called after the update calls to vsyscall and
pvclock. While not correct, it did not cause any problems because none
of the invoked update functions used base_mono.

commit cbcf2dd3b3 (x86: kvm: Make kvm_get_time_and_clockread()
nanoseconds based) changed that in the kvm pvclock update function, so
the stale mono_base value got used and caused kvm-clock to malfunction.

Put the update where it belongs and fix the issue.

Reported-by: Chris J Arges <chris.j.arges@canonical.com>
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1409050000570.3333@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-09-06 12:58:18 +02:00
Thomas Gleixner 849151dd54 compat: nanosleep: Clarify error handling
The error handling in compat_sys_nanosleep() is correct, but
completely non obvious. Document it and restrict it to the
-ERESTART_RESTARTBLOCK return value for clarity.

Reported-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2014-09-06 12:58:18 +02:00
Daniel Borkmann 60a3b2253c net: bpf: make eBPF interpreter images read-only
With eBPF getting more extended and exposure to user space is on it's way,
hardening the memory range the interpreter uses to steer its command flow
seems appropriate.  This patch moves the to be interpreted bytecode to
read-only pages.

In case we execute a corrupted BPF interpreter image for some reason e.g.
caused by an attacker which got past a verifier stage, it would not only
provide arbitrary read/write memory access but arbitrary function calls
as well. After setting up the BPF interpreter image, its contents do not
change until destruction time, thus we can setup the image on immutable
made pages in order to mitigate modifications to that code. The idea
is derived from commit 314beb9bca ("x86: bpf_jit_comp: secure bpf jit
against spraying attacks").

This is possible because bpf_prog is not part of sk_filter anymore.
After setup bpf_prog cannot be altered during its life-time. This prevents
any modifications to the entire bpf_prog structure (incl. function/JIT
image pointer).

Every eBPF program (including classic BPF that are migrated) have to call
bpf_prog_select_runtime() to select either interpreter or a JIT image
as a last setup step, and they all are being freed via bpf_prog_free(),
including non-JIT. Therefore, we can easily integrate this into the
eBPF life-time, plus since we directly allocate a bpf_prog, we have no
performance penalty.

Tested with seccomp and test_bpf testsuite in JIT/non-JIT mode and manual
inspection of kernel_page_tables.  Brad Spengler proposed the same idea
via Twitter during development of this patch.

Joint work with Hannes Frederic Sowa.

Suggested-by: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Kees Cook <keescook@chromium.org>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-05 12:02:48 -07:00
Andreea-Cristina Bernat 35b123e2f7 sched/fair: Replace rcu_assign_pointer() with RCU_INIT_POINTER()
The use of "rcu_assign_pointer()" is NULLing out the pointer.
According to RCU_INIT_POINTER()'s block comment:

  "1.   This use of RCU_INIT_POINTER() is NULLing out the pointer"

it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.

The following Coccinelle semantic patch was used:
 @@
 @@

 - rcu_assign_pointer
 + RCU_INIT_POINTER
   (..., NULL)

Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: paulmck@linux.vnet.ibm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140822145043.GA580@ada
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-05 08:11:57 +02:00
Thierry Reding 8d38821cbc resources: Add device-managed request/release_resource()
Provide device-managed implementations of the request_resource() and
release_resource() functions.  Upon failure to request a resource, the new
devm_request_resource() function will output an error message for
consistent error reporting.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
2014-09-04 14:41:43 -06:00
Frederic Weisbecker 40bea03959 nohz: Restore NMI safe local irq work for local nohz kick
The local nohz kick is currently used by perf which needs it to be
NMI-safe. Recent commit though (7d1311b93e)
changed its implementation to fire the local kick using the remote kick
API. It was convenient to make the code more generic but the remote kick
isn't NMI-safe.

As a result:

	WARNING: CPU: 3 PID: 18062 at kernel/irq_work.c:72 irq_work_queue_on+0x11e/0x140()
	CPU: 3 PID: 18062 Comm: trinity-subchil Not tainted 3.16.0+ #34
	0000000000000009 00000000903774d1 ffff880244e06c00 ffffffff9a7f1e37
	0000000000000000 ffff880244e06c38 ffffffff9a0791dd ffff880244fce180
	0000000000000003 ffff880244e06d58 ffff880244e06ef8 0000000000000000
	Call Trace:
	<NMI>  [<ffffffff9a7f1e37>] dump_stack+0x4e/0x7a
	[<ffffffff9a0791dd>] warn_slowpath_common+0x7d/0xa0
	[<ffffffff9a07930a>] warn_slowpath_null+0x1a/0x20
	[<ffffffff9a17ca1e>] irq_work_queue_on+0x11e/0x140
	[<ffffffff9a10a2c7>] tick_nohz_full_kick_cpu+0x57/0x90
	[<ffffffff9a186cd5>] __perf_event_overflow+0x275/0x350
	[<ffffffff9a184f80>] ? perf_event_task_disable+0xa0/0xa0
	[<ffffffff9a01a4cf>] ? x86_perf_event_set_period+0xbf/0x150
	[<ffffffff9a187934>] perf_event_overflow+0x14/0x20
	[<ffffffff9a020386>] intel_pmu_handle_irq+0x206/0x410
	[<ffffffff9a0b54d3>] ? arch_vtime_task_switch+0x63/0x130
	[<ffffffff9a01937b>] perf_event_nmi_handler+0x2b/0x50
	[<ffffffff9a007b72>] nmi_handle+0xd2/0x390
	[<ffffffff9a007aa5>] ? nmi_handle+0x5/0x390
	[<ffffffff9a0d131b>] ? lock_release+0xab/0x330
	[<ffffffff9a008062>] default_do_nmi+0x72/0x1c0
	[<ffffffff9a0c925f>] ? cpuacct_account_field+0xcf/0x200
	[<ffffffff9a008268>] do_nmi+0xb8/0x100

Lets fix this by restoring the use of local irq work for the nohz local
kick.

Reported-by: Catalin Iacob <iacobcatalin@gmail.com>
Reported-and-tested-by: Dave Jones <davej@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-09-04 22:35:59 +02:00
Li Zefan aa32362f01 cgroup: check cgroup liveliness before unbreaking kernfs
When cgroup_kn_lock_live() is called through some kernfs operation and
another thread is calling cgroup_rmdir(), we'll trigger the warning in
cgroup_get().

------------[ cut here ]------------
WARNING: CPU: 1 PID: 1228 at kernel/cgroup.c:1034 cgroup_get+0x89/0xa0()
...
Call Trace:
 [<c16ee73d>] dump_stack+0x41/0x52
 [<c10468ef>] warn_slowpath_common+0x7f/0xa0
 [<c104692d>] warn_slowpath_null+0x1d/0x20
 [<c10bb999>] cgroup_get+0x89/0xa0
 [<c10bbe58>] cgroup_kn_lock_live+0x28/0x70
 [<c10be3c1>] __cgroup_procs_write.isra.26+0x51/0x230
 [<c10be5b2>] cgroup_tasks_write+0x12/0x20
 [<c10bb7b0>] cgroup_file_write+0x40/0x130
 [<c11aee71>] kernfs_fop_write+0xd1/0x160
 [<c1148e58>] vfs_write+0x98/0x1e0
 [<c114934d>] SyS_write+0x4d/0xa0
 [<c16f656b>] sysenter_do_call+0x12/0x12
---[ end trace 6f2e0c38c2108a74 ]---

Fix this by calling css_tryget() instead of cgroup_get().

v2:
- move cgroup_tryget() right below cgroup_get() definition. (Tejun)

Cc: <stable@vger.kernel.org> # 3.15+
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-05 01:36:19 +09:00
Li Zefan a4189487da cgroup: delay the clearing of cgrp->kn->priv
Run these two scripts concurrently:

    for ((; ;))
    {
        mkdir /cgroup/sub
        rmdir /cgroup/sub
    }

    for ((; ;))
    {
        echo $$ > /cgroup/sub/cgroup.procs
        echo $$ > /cgroup/cgroup.procs
    }

A kernel bug will be triggered:

BUG: unable to handle kernel NULL pointer dereference at 00000038
IP: [<c10bbd69>] cgroup_put+0x9/0x80
...
Call Trace:
 [<c10bbe19>] cgroup_kn_unlock+0x39/0x50
 [<c10bbe91>] cgroup_kn_lock_live+0x61/0x70
 [<c10be3c1>] __cgroup_procs_write.isra.26+0x51/0x230
 [<c10be5b2>] cgroup_tasks_write+0x12/0x20
 [<c10bb7b0>] cgroup_file_write+0x40/0x130
 [<c11aee71>] kernfs_fop_write+0xd1/0x160
 [<c1148e58>] vfs_write+0x98/0x1e0
 [<c114934d>] SyS_write+0x4d/0xa0
 [<c16f656b>] sysenter_do_call+0x12/0x12

We clear cgrp->kn->priv in the end of cgroup_rmdir(), but another
concurrent thread can access kn->priv after the clearing.

We should move the clearing to css_release_work_fn(). At that time
no one is holding reference to the cgroup and no one can gain a new
reference to access it.

v2:
- move RCU_INIT_POINTER() into the else block. (Tejun)
- remove the cgroup_parent() check. (Tejun)
- update the comment in css_tryget_online_from_dir().

Cc: <stable@vger.kernel.org> # 3.15+
Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-09-05 01:36:18 +09:00
Mark Rustad 315427691c locking/semaphore: Resolve some shadow warnings
Resolve some shadow warnings resulting from using the name
jiffies, which is a well-known global. This is not a problem
of course, but it could be a trap for someone copying and
pasting code, and it just makes W=2 a little cleaner.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1409739444-13635-1-git-send-email-jeffrey.t.kirsher@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-04 07:17:24 +02:00
Andy Lutomirski d39bd00dea seccomp: Allow arch code to provide seccomp_data
populate_seccomp_data is expensive: it works by inspecting
task_pt_regs and various other bits to piece together all the
information, and it's does so in multiple partially redundant steps.

Arch-specific code in the syscall entry path can do much better.

Admittedly this adds a bit of additional room for error, but the
speedup should be worth it.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
2014-09-03 14:58:17 -07:00
Andy Lutomirski 13aa72f0fd seccomp: Refactor the filter callback and the API
The reason I did this is to add a seccomp API that will be usable
for an x86 fast path.  The x86 entry code needs to use a rather
expensive slow path for a syscall that might be visible to things
like ptrace.  By splitting seccomp into two phases, we can check
whether we need the slow path and then use the fast path in if the
filter allows the syscall or just returns some errno.

As a side effect, I think the new code is much easier to understand
than the old code.

This has one user-visible effect: the audit record written for
SECCOMP_RET_TRACE is now a simple indication that SECCOMP_RET_TRACE
happened.  It used to depend in a complicated way on what the tracer
did.  I couldn't make much sense of it.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
2014-09-03 14:58:17 -07:00
Andy Lutomirski a4412fc948 seccomp,x86,arm,mips,s390: Remove nr parameter from secure_computing
The secure_computing function took a syscall number parameter, but
it only paid any attention to that parameter if seccomp mode 1 was
enabled.  Rather than coming up with a kludge to get the parameter
to work in mode 2, just remove the parameter.

To avoid churn in arches that don't have seccomp filters (and may
not even support syscall_get_nr right now), this leaves the
parameter in secure_computing_strict, which is now a real function.

For ARM, this is a bit ugly due to the fact that ARM conditionally
supports seccomp filters.  Fixing that would probably only be a
couple of lines of code, but it should be coordinated with the audit
maintainers.

This will be a slight slowdown on some arches.  The right fix is to
pass in all of seccomp_data instead of trying to make just the
syscall nr part be fast.

This is a prerequisite for making two-phase seccomp work cleanly.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: x86@kernel.org
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
2014-09-03 14:58:17 -07:00
Marc Zyngier 76ba59f836 genirq: Add irq_domain-aware core IRQ handler
Calling irq_find_mapping from outside a irq_{enter,exit} section is
unsafe and produces ugly messages if CONFIG_PROVE_RCU is enabled:
If coming from the idle state, the rcu_read_lock call in irq_find_mapping
will generate an unpleasant warning:

<quote>
===============================
[ INFO: suspicious RCU usage. ]
3.16.0-rc1+ #135 Not tainted
-------------------------------
include/linux/rcupdate.h:871 rcu_read_lock() used illegally while idle!

other info that might help us debug this:

RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
1 lock held by swapper/0/0:
 #0:  (rcu_read_lock){......}, at: [<ffffffc00010206c>]
irq_find_mapping+0x4c/0x198
</quote>

As this issue is fairly widespread and involves at least three
different architectures, a possible solution is to add a new
handle_domain_irq entry point into the generic IRQ code that
the interrupt controller code can call.

This new function takes an irq_domain, and calls into irq_find_domain
inside the irq_{enter,exit} block. An additional "lookup" parameter is
used to allow non-domain architecture code to be replaced by this as well.

Interrupt controllers can then be updated to use the new mechanism.

This code is sitting behind a new CONFIG_HANDLE_DOMAIN_IRQ, as not all
architectures implement set_irq_regs (yes, mn10300, I'm looking at you...).

Reported-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1409047421-27649-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
2014-09-03 12:57:27 +00:00
Ingo Molnar 651bc1a474 Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent
Pull an RCU fix from Paul E. McKenney:

 "This series contains a single commit fixing an initialization bug
  reported by Amit Shah and fixed by Pranith Kumar (and tested by Amit).
  This bug results in a boot-time hang in callback-offloaded configurations
  where callbacks were posted before the offloading ('rcuo') kthreads
  were created."

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-03 10:46:51 +02:00
Rafael J. Wysocki 62109b4317 PM / sleep: Fix test_suspend= command line option
After commit d431cbc53c (PM / sleep: Simplify sleep states sysfs
interface code) the pm_states[] array is not populated initially,
which causes setup_test_suspend() to always fail and the suspend
testing during boot doesn't work any more.

Fix the problem by using pm_labels[] instead of pm_states[] in
setup_test_suspend() and storing a pointer to the label of the
sleep state to test rather than the number representing it,
because the connection between the state numbers and labels is
only established by suspend_set_ops().

Fixes: d431cbc53c (PM / sleep: Simplify sleep states sysfs interface code)
Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-03 01:21:03 +02:00
Linus Torvalds 7505ceaf86 Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq handling fixlet from Thomas Gleixner:
 "Just an export for an interrupt flow handler which is now used in gpio
  modules"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irq: Export handle_fasteoi_irq
2014-09-01 10:36:27 -07:00
Thomas Gleixner 9ce7a25849 genirq: Simplify wakeup mechanism
Currently we suspend wakeup interrupts by lazy disabling them and
check later whether the interrupt has fired, but that's not sufficient
for suspend to idle as there is no way to check that once we
transitioned into the CPU idle state.

So we change the mechanism in the following way:

1) Leave the wakeup interrupts enabled across suspend

2) Add a check to irq_may_run() which is called at the beginning of
   each flow handler whether the interrupt is an armed wakeup source.

   This check is basically free as it just extends the existing check
   for IRQD_IRQ_INPROGRESS. So no new conditional in the hot path.

   If the IRQD_WAKEUP_ARMED flag is set, then the interrupt is
   disabled, marked as pending/suspended and the pm core is notified
   about the wakeup event.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ rjw: syscore.c and put irq_pm_check_wakeup() into pm.c ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-01 13:48:59 +02:00