Commit Graph

123 Commits

Author SHA1 Message Date
Yaowei Bai 77ef80c65a kernel/cpuset: current_cpuset_is_being_rebound can be boolean
Make current_cpuset_is_being_rebound return bool due to this particular
function only using either one or zero as its return value.

No functional change.

Link: http://lkml.kernel.org/r/1513266622-15860-4-git-send-email-baiyaowei@cmss.chinamobile.com
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06 18:32:47 -08:00
Tejun Heo 08a77676f9 string: drop __must_check from strscpy() and restore strscpy() usages in cgroup
e7fd37ba12 ("cgroup: avoid copying strings longer than the buffers")
converted possibly unsafe strncpy() usages in cgroup to strscpy().
However, although the callsites are completely fine with truncated
copied, because strscpy() is marked __must_check, it led to the
following warnings.

  kernel/cgroup/cgroup.c: In function ‘cgroup_file_name’:
  kernel/cgroup/cgroup.c:1400:10: warning: ignoring return value of ‘strscpy’, declared with attribute warn_unused_result [-Wunused-result]
     strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
	       ^

To avoid the warnings, 50034ed496 ("cgroup: use strlcpy() instead of
strscpy() to avoid spurious warning") switched them to strlcpy().

strlcpy() is worse than strlcpy() because it unconditionally runs
strlen() on the source string, and the only reason we switched to
strlcpy() here was because it was lacking __must_check, which doesn't
reflect any material differences between the two function.  It's just
that someone added __must_check to strscpy() and not to strlcpy().

These basic string copy operations are used in variety of ways, and
one of not-so-uncommon use cases is safely handling truncated copies,
where the caller naturally doesn't care about the return value.  The
__must_check doesn't match the actual use cases and forces users to
opt for inferior variants which lack __must_check by happenstance or
spread ugly (void) casts.

Remove __must_check from strscpy() and restore strscpy() usages in
cgroup.

Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ma Shimiao <mashimiao.fnst@cn.fujitsu.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
2018-01-19 08:51:36 -08:00
Roman Gushchin 4f58424da3 cgroup: make cgroup.threads delegatable
Make cgroup.threads file delegatable.
The behavior of cgroup.threads should follow the behavior of cgroup.procs.

Signed-off-by: Roman Gushchin <guro@fb.com>
Discovered-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2018-01-10 09:42:32 -08:00
Tejun Heo 74d0833c65 cgroup: fix css_task_iter crash on CSS_TASK_ITER_PROC
While teaching css_task_iter to handle skipping over tasks which
aren't group leaders, bc2fb7ed08 ("cgroup: add @flags to
css_task_iter_start() and implement CSS_TASK_ITER_PROCS") introduced a
silly bug.

CSS_TASK_ITER_PROCS is implemented by repeating
css_task_iter_advance() while the advanced cursor is pointing to a
non-leader thread.  However, the cursor variable, @l, wasn't updated
when the iteration has to advance to the next css_set and the
following repetition would operate on the terminal @l from the
previous iteration which isn't pointing to a valid task leading to
oopses like the following or infinite looping.

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000254
  IP: __task_pid_nr_ns+0xc7/0xf0
  PGD 0 P4D 0
  Oops: 0000 [#1] SMP
  ...
  CPU: 2 PID: 1 Comm: systemd Not tainted 4.14.4-200.fc26.x86_64 #1
  Hardware name: System manufacturer System Product Name/PRIME B350M-A, BIOS 3203 11/09/2017
  task: ffff88c4baee8000 task.stack: ffff96d5c3158000
  RIP: 0010:__task_pid_nr_ns+0xc7/0xf0
  RSP: 0018:ffff96d5c315bd50 EFLAGS: 00010206
  RAX: 0000000000000000 RBX: ffff88c4b68c6000 RCX: 0000000000000250
  RDX: ffffffffa5e47960 RSI: 0000000000000000 RDI: ffff88c490f6ab00
  RBP: ffff96d5c315bd50 R08: 0000000000001000 R09: 0000000000000005
  R10: ffff88c4be006b80 R11: ffff88c42f1b8004 R12: ffff96d5c315bf18
  R13: ffff88c42d7dd200 R14: ffff88c490f6a510 R15: ffff88c4b68c6000
  FS:  00007f9446f8ea00(0000) GS:ffff88c4be680000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000254 CR3: 00000007f956f000 CR4: 00000000003406e0
  Call Trace:
   cgroup_procs_show+0x19/0x30
   cgroup_seqfile_show+0x4c/0xb0
   kernfs_seq_show+0x21/0x30
   seq_read+0x2ec/0x3f0
   kernfs_fop_read+0x134/0x180
   __vfs_read+0x37/0x160
   ? security_file_permission+0x9b/0xc0
   vfs_read+0x8e/0x130
   SyS_read+0x55/0xc0
   entry_SYSCALL_64_fastpath+0x1a/0xa5
  RIP: 0033:0x7f94455f942d
  RSP: 002b:00007ffe81ba2d00 EFLAGS: 00000293 ORIG_RAX: 0000000000000000
  RAX: ffffffffffffffda RBX: 00005574e2233f00 RCX: 00007f94455f942d
  RDX: 0000000000001000 RSI: 00005574e2321a90 RDI: 000000000000002b
  RBP: 0000000000000000 R08: 00005574e2321a90 R09: 00005574e231de60
  R10: 00007f94458c8b38 R11: 0000000000000293 R12: 00007f94458c8ae0
  R13: 00007ffe81ba3800 R14: 0000000000000000 R15: 00005574e2116560
  Code: 04 74 0e 89 f6 48 8d 04 76 48 8d 04 c5 f0 05 00 00 48 8b bf b8 05 00 00 48 01 c7 31 c0 48 8b 0f 48 85 c9 74 18 8b b2 30 08 00 00 <3b> 71 04 77 0d 48 c1 e6 05 48 01 f1 48 3b 51 38 74 09 5d c3 8b
  RIP: __task_pid_nr_ns+0xc7/0xf0 RSP: ffff96d5c315bd50

Fix it by moving the initialization of the cursor below the repeat
label.  While at it, rename it to @next for readability.

Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: bc2fb7ed08 ("cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS")
Cc: stable@vger.kernel.org # v4.14+
Reported-by: Laura Abbott <labbott@redhat.com>
Reported-by: Bronek Kozicki <brok@incorrekt.com>
Reported-by: George Amanakis <gamanakis@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-12-20 07:09:19 -08:00
Prateek Sood 116d2f7496 cgroup: Fix deadlock in cpu hotplug path
Deadlock during cgroup migration from cpu hotplug path when a task T is
being moved from source to destination cgroup.

kworker/0:0
cpuset_hotplug_workfn()
   cpuset_hotplug_update_tasks()
      hotplug_update_tasks_legacy()
        remove_tasks_in_empty_cpuset()
          cgroup_transfer_tasks() // stuck in iterator loop
            cgroup_migrate()
              cgroup_migrate_add_task()

In cgroup_migrate_add_task() it checks for PF_EXITING flag of task T.
Task T will not migrate to destination cgroup. css_task_iter_start()
will keep pointing to task T in loop waiting for task T cg_list node
to be removed.

Task T
do_exit()
  exit_signals() // sets PF_EXITING
  exit_task_namespaces()
    switch_task_namespaces()
      free_nsproxy()
        put_mnt_ns()
          drop_collected_mounts()
            namespace_unlock()
              synchronize_rcu()
                _synchronize_rcu_expedited()
                  schedule_work() // on cpu0 low priority worker pool
                  wait_event() // waiting for work item to execute

Task T inserted a work item in the worklist of cpu0 low priority
worker pool. It is waiting for expedited grace period work item
to execute. This work item will only be executed once kworker/0:0
complete execution of cpuset_hotplug_workfn().

kworker/0:0 ==> Task T ==>kworker/0:0

In case of PF_EXITING task being migrated from source to destination
cgroup, migrate next available task in source cgroup.

Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-12-19 05:38:47 -08:00
Arnd Bergmann 50034ed496 cgroup: use strlcpy() instead of strscpy() to avoid spurious warning
As long as cft->name is guaranteed to be NUL-terminated, using strlcpy() would
work just as well and avoid that warning, so the change below could be folded
into that commit.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-12-15 05:09:47 -08:00
Ma Shimiao e7fd37ba12 cgroup: avoid copying strings longer than the buffers
cgroup root name and file name have max length limit, we should
avoid copying longer name than that to the name.

tj: minor update to $SUBJ.

Signed-off-by: Ma Shimiao <mashimiao.fnst@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-12-12 07:53:29 -08:00
Tejun Heo bdfbbda90a Revert "cgroup/cpuset: remove circular dependency deadlock"
This reverts commit aa24163b2e.

This and the following commit led to another circular locking scenario
and the scenario which is fixed by this commit no longer exists after
e8b3f8db7a ("workqueue/hotplug: simplify workqueue_offline_cpu()")
which removes work item flushing from hotplug path.

Revert it for now.

Signed-off-by: Tejun Heo <tj@kernel.org>
2017-12-04 14:55:59 -08:00
Tejun Heo 11db855c3d Revert "cpuset: Make cpuset hotplug synchronous"
This reverts commit 1599a185f0.

This and the previous commit led to another circular locking scenario
and the scenario which is fixed by this commit no longer exists after
e8b3f8db7a ("workqueue/hotplug: simplify workqueue_offline_cpu()")
which removes work item flushing from hotplug path.

Revert it for now.

Signed-off-by: Tejun Heo <tj@kernel.org>
2017-12-04 14:41:11 -08:00
Lucas Stach 52cf373c37 cgroup: properly init u64_stats
Lockdep complains that the stats update is trying to register a non-static
key. This is because u64_stats are using a seqlock on 32bit arches, which
needs to be initialized before usage.

Fixes: 041cd640b2 (cgroup: Implement cgroup2 basic CPU usage accounting)
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-11-28 07:16:08 -08:00
Wang Long ddf7005f32 debug cgroup: use task_css_set instead of rcu_dereference
This macro `task_css_set` verifies that the caller is
inside proper critical section if the kernel set CONFIG_PROVE_RCU=y.

Signed-off-by: Wang Long <wanglong19@meituan.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-11-27 11:37:33 -08:00
Prateek Sood 1599a185f0 cpuset: Make cpuset hotplug synchronous
Convert cpuset_hotplug_workfn() into synchronous call for cpu hotplug
path. For memory hotplug path it still gets queued as a work item.

Since cpuset_hotplug_workfn() can be made synchronous for cpu hotplug
path, it is not required to wait for cpuset hotplug while thawing
processes.

Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-11-27 08:48:10 -08:00
Prateek Sood aa24163b2e cgroup/cpuset: remove circular dependency deadlock
Remove circular dependency deadlock in a scenario where hotplug of CPU is
being done while there is updation in cgroup and cpuset triggered from
userspace.

Process A => kthreadd => Process B => Process C => Process A

Process A
cpu_subsys_offline();
  cpu_down();
    _cpu_down();
      percpu_down_write(&cpu_hotplug_lock); //held
      cpuhp_invoke_callback();
	     workqueue_offline_cpu();
            queue_work_on(); // unbind_work on system_highpri_wq
               __queue_work();
                 insert_work();
                    wake_up_worker();
            flush_work();
               wait_for_completion();

worker_thread();
   manage_workers();
      create_worker();
	     kthread_create_on_node();
		    wake_up_process(kthreadd_task);

kthreadd
kthreadd();
  kernel_thread();
    do_fork();
      copy_process();
        percpu_down_read(&cgroup_threadgroup_rwsem);
          __rwsem_down_read_failed_common(); //waiting

Process B
kernfs_fop_write();
  cgroup_file_write();
    cgroup_procs_write();
      percpu_down_write(&cgroup_threadgroup_rwsem); //held
      cgroup_attach_task();
        cgroup_migrate();
          cgroup_migrate_execute();
            cpuset_can_attach();
              mutex_lock(&cpuset_mutex); //waiting

Process C
kernfs_fop_write();
  cgroup_file_write();
    cpuset_write_resmask();
      mutex_lock(&cpuset_mutex); //held
      update_cpumask();
        update_cpumasks_hier();
          rebuild_sched_domains_locked();
            get_online_cpus();
              percpu_down_read(&cpu_hotplug_lock); //waiting

Eliminating deadlock by reversing the locking order for cpuset_mutex and
cpu_hotplug_lock.

Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-11-27 08:48:10 -08:00
Linus Torvalds 22714a2ba4 Merge branch 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "Cgroup2 cpu controller support is finally merged.

   - Basic cpu statistics support to allow monitoring by default without
     the CPU controller enabled.

   - cgroup2 cpu controller support.

   - /sys/kernel/cgroup files to help dealing with new / optional
     features"

* 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: export list of cgroups v2 features using sysfs
  cgroup: export list of delegatable control files using sysfs
  cgroup: mark @cgrp __maybe_unused in cpu_stat_show()
  MAINTAINERS: relocate cpuset.c
  cgroup, sched: Move basic cpu stats from cgroup.stat to cpu.stat
  sched: Implement interface for cgroup unified hierarchy
  sched: Misc preps for cgroup unified hierarchy interface
  sched/cputime: Add dummy cputime_adjust() implementation for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
  cgroup: statically initialize init_css_set->dfl_cgrp
  cgroup: Implement cgroup2 basic CPU usage accounting
  cpuacct: Introduce cgroup_account_cputime[_field]()
  sched/cputime: Expose cputime_adjust()
2017-11-15 14:29:44 -08:00
Linus Torvalds 5bbcc0f595 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller:
 "Highlights:

   1) Maintain the TCP retransmit queue using an rbtree, with 1GB
      windows at 100Gb this really has become necessary. From Eric
      Dumazet.

   2) Multi-program support for cgroup+bpf, from Alexei Starovoitov.

   3) Perform broadcast flooding in hardware in mv88e6xxx, from Andrew
      Lunn.

   4) Add meter action support to openvswitch, from Andy Zhou.

   5) Add a data meta pointer for BPF accessible packets, from Daniel
      Borkmann.

   6) Namespace-ify almost all TCP sysctl knobs, from Eric Dumazet.

   7) Turn on Broadcom Tags in b53 driver, from Florian Fainelli.

   8) More work to move the RTNL mutex down, from Florian Westphal.

   9) Add 'bpftool' utility, to help with bpf program introspection.
      From Jakub Kicinski.

  10) Add new 'cpumap' type for XDP_REDIRECT action, from Jesper
      Dangaard Brouer.

  11) Support 'blocks' of transformations in the packet scheduler which
      can span multiple network devices, from Jiri Pirko.

  12) TC flower offload support in cxgb4, from Kumar Sanghvi.

  13) Priority based stream scheduler for SCTP, from Marcelo Ricardo
      Leitner.

  14) Thunderbolt networking driver, from Amir Levy and Mika Westerberg.

  15) Add RED qdisc offloadability, and use it in mlxsw driver. From
      Nogah Frankel.

  16) eBPF based device controller for cgroup v2, from Roman Gushchin.

  17) Add some fundamental tracepoints for TCP, from Song Liu.

  18) Remove garbage collection from ipv6 route layer, this is a
      significant accomplishment. From Wei Wang.

  19) Add multicast route offload support to mlxsw, from Yotam Gigi"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (2177 commits)
  tcp: highest_sack fix
  geneve: fix fill_info when link down
  bpf: fix lockdep splat
  net: cdc_ncm: GetNtbFormat endian fix
  openvswitch: meter: fix NULL pointer dereference in ovs_meter_cmd_reply_start
  netem: remove unnecessary 64 bit modulus
  netem: use 64 bit divide by rate
  tcp: Namespace-ify sysctl_tcp_default_congestion_control
  net: Protect iterations over net::fib_notifier_ops in fib_seq_sum()
  ipv6: set all.accept_dad to 0 by default
  uapi: fix linux/tls.h userspace compilation error
  usbnet: ipheth: prevent TX queue timeouts when device not ready
  vhost_net: conditionally enable tx polling
  uapi: fix linux/rxrpc.h userspace compilation errors
  net: stmmac: fix LPI transitioning for dwmac4
  atm: horizon: Fix irq release error
  net-sysfs: trigger netlink notification on ifalias change via sysfs
  openvswitch: Using kfree_rcu() to simplify the code
  openvswitch: Make local function ovs_nsh_key_attr_size() static
  openvswitch: Fix return value check in ovs_meter_cmd_features()
  ...
2017-11-15 11:56:19 -08:00
Ingo Molnar 8a103df440 Merge branch 'linus' into sched/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-08 10:17:15 +01:00
Roman Gushchin 5f2e673405 cgroup: export list of cgroups v2 features using sysfs
The active development of cgroups v2 sometimes leads to a creation
of interfaces, which are not turned on by default (to provide
backward compatibility). It's handy to know from userspace, which
cgroup v2 features are supported without calculating it based
on the kernel version. So, let's export the list of such features
using /sys/kernel/cgroup/features pseudo-file.

The list is hardcoded and has to be extended when new functionality
is added. Each feature is printed on a new line.

Example:
  $ cat /sys/kernel/cgroup/features
  nsdelegate

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: kernel-team@fb.com
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-11-06 12:01:57 -08:00
Roman Gushchin 01ee6cfb14 cgroup: export list of delegatable control files using sysfs
Delegatable cgroup v2 control files may require special handling
(e.g. chowning), and the exact list of such files varies between
kernel versions (and likely to be extended in the future).

To guarantee correctness of this list and simplify the life
of userspace (systemd, first of all), let's export the list
via /sys/kernel/cgroup/delegate pseudo-file.

Format is siple: each control file name is printed on a new line.
Example:
  $ cat /sys/kernel/cgroup/delegate
  cgroup.procs
  cgroup.subtree_control

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: kernel-team@fb.com
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-11-06 12:01:54 -08:00
David S. Miller 2a171788ba Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Files removed in 'net-next' had their license header updated
in 'net'.  We take the remove from 'net-next'.

Signed-off-by: David S. Miller <davem@davemloft.net>
2017-11-04 09:26:51 +09:00
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Tejun Heo c3ba132987 cgroup: mark @cgrp __maybe_unused in cpu_stat_show()
The local variable @cgrp isn't used if !CONFIG_CGROUP_SCHED.  Mark the
variable with __maybe_unused to avoid a compile warning.

Reported-by: "kbuild-all@01.org" <kbuild-all@01.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-10-30 08:13:14 -07:00
Frederic Weisbecker edb9382175 sched/isolation: Move isolcpus= handling to the housekeeping code
We want to centralize the isolation features, to be done by the housekeeping
subsystem and scheduler domain isolation is a significant part of it.

No intended behaviour change, we just reuse the housekeeping cpumask
and core code.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1509072159-31808-11-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-27 09:55:30 +02:00
Tejun Heo d41bf8c9de cgroup, sched: Move basic cpu stats from cgroup.stat to cpu.stat
The basic cpu stat is currently shown with "cpu." prefix in
cgroup.stat, and the same information is duplicated in cpu.stat when
cpu controller is enabled.  This is ugly and not very scalable as we
want to expand the coverage of stat information which is always
available.

This patch makes cgroup core always create "cpu.stat" file and show
the basic cpu stat there and calls the cpu controller to show the
extra stats when enabled.  This ensures that the same information
isn't presented in multiple places and makes future expansion of basic
stats easier.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2017-10-26 10:56:33 -07:00
David S. Miller 53954cf8c5 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Just simple overlapping changes.

Signed-off-by: David S. Miller <davem@davemloft.net>
2017-10-05 18:19:22 -07:00
Alexei Starovoitov 468e2f64d2 bpf: introduce BPF_PROG_QUERY command
introduce BPF_PROG_QUERY command to retrieve a set of either
attached programs to given cgroup or a set of effective programs
that will execute for events within a cgroup

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
for cgroup bits
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-10-04 16:05:05 -07:00
Alexei Starovoitov 324bda9e6c bpf: multi program support for cgroup+bpf
introduce BPF_F_ALLOW_MULTI flag that can be used to attach multiple
bpf programs to a cgroup.

The difference between three possible flags for BPF_PROG_ATTACH command:
- NONE(default): No further bpf programs allowed in the subtree.
- BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
  the program in this cgroup yields to sub-cgroup program.
- BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
  that cgroup program gets run in addition to the program in this cgroup.

NONE and BPF_F_ALLOW_OVERRIDE existed before. This patch doesn't
change their behavior. It only clarifies the semantics in relation
to new flag.

Only one program is allowed to be attached to a cgroup with
NONE or BPF_F_ALLOW_OVERRIDE flag.
Multiple programs are allowed to be attached to a cgroup with
BPF_F_ALLOW_MULTI flag. They are executed in FIFO order
(those that were attached first, run first)
The programs of sub-cgroup are executed first, then programs of
this cgroup and then programs of parent cgroup.
All eligible programs are executed regardless of return code from
earlier programs.

To allow efficient execution of multiple programs attached to a cgroup
and to avoid penalizing cgroups without any programs attached
introduce 'struct bpf_prog_array' which is RCU protected array
of pointers to bpf programs.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
for cgroup bits
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-10-04 16:05:05 -07:00
Tejun Heo 3868314882 cgroup: statically initialize init_css_set->dfl_cgrp
Like other csets, init_css_set's dfl_cgrp is initialized when the cset
gets linked.  init_css_set gets linked in cgroup_init().  This has
been fine till now but the recently added basic CPU usage accounting
may end up accessing dfl_cgrp of init before cgroup_init() leading to
the following oops.

  SELinux:  Initializing.
  BUG: unable to handle kernel NULL pointer dereference at 00000000000000b0
  IP: account_system_index_time+0x60/0x90
  PGD 0 P4D 0
  Oops: 0000 [#1] SMP
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.14.0-rc2-00003-g041cd64 #10
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
  +1.9.3-20161025_171302-gandalf 04/01/2014
  task: ffffffff81e10480 task.stack: ffffffff81e00000
  RIP: 0010:account_system_index_time+0x60/0x90
  RSP: 0000:ffff880011e03cb8 EFLAGS: 00010002
  RAX: ffffffff81ef8800 RBX: ffffffff81e10480 RCX: 0000000000000003
  RDX: 0000000000000000 RSI: 00000000000f4240 RDI: 0000000000000000
  RBP: ffff880011e03cc0 R08: 0000000000010000 R09: 0000000000000000
  R10: 0000000000000020 R11: 0000003b9aca0000 R12: 000000000001c100
  R13: 0000000000000000 R14: ffffffff81e10480 R15: ffffffff81e03cd8
  FS:  0000000000000000(0000) GS:ffff880011e00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00000000000000b0 CR3: 0000000001e09000 CR4: 00000000000006b0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   <IRQ>
   account_system_time+0x45/0x60
   account_process_tick+0x5a/0x140
   update_process_times+0x22/0x60
   tick_periodic+0x2b/0x90
   tick_handle_periodic+0x25/0x70
   timer_interrupt+0x15/0x20
   __handle_irq_event_percpu+0x7e/0x1b0
   handle_irq_event_percpu+0x23/0x60
   handle_irq_event+0x42/0x70
   handle_level_irq+0x83/0x100
   handle_irq+0x6f/0x110
   do_IRQ+0x46/0xd0
   common_interrupt+0x9d/0x9d

Fix it by statically initializing init_css_set.dfl_cgrp so that init's
default cgroup is accessible from the get-go.

Fixes: 041cd640b2 ("cgroup: Implement cgroup2 basic CPU usage accounting")
Reported-by: “kbuild-all@01.org” <kbuild-all@01.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-09-25 14:02:53 -07:00
Tejun Heo 041cd640b2 cgroup: Implement cgroup2 basic CPU usage accounting
In cgroup1, while cpuacct isn't actually controlling any resources, it
is a separate controller due to combination of two factors -
1. enabling cpu controller has significant side effects, and 2. we
have to pick one of the hierarchies to account CPU usages on.  cpuacct
controller is effectively used to designate a hierarchy to track CPU
usages on.

cgroup2's unified hierarchy removes the second reason and we can
account basic CPU usages by default.  While we can use cpuacct for
this purpose, both its interface and implementation leave a lot to be
desired - it collects and exposes two sources of truth which don't
agree with each other and some of the exposed statistics don't make
much sense.  Also, it propagates all the way up the hierarchy on each
accounting event which is unnecessary.

This patch adds basic resource accounting mechanism to cgroup2's
unified hierarchy and accounts CPU usages using it.

* All accountings are done per-cpu and don't propagate immediately.
  It just bumps the per-cgroup per-cpu counters and links to the
  parent's updated list if not already on it.

* On a read, the per-cpu counters are collected into the global ones
  and then propagated upwards.  Only the per-cpu counters which have
  changed since the last read are propagated.

* CPU usage stats are collected and shown in "cgroup.stat" with "cpu."
  prefix.  Total usage is collected from scheduling events.  User/sys
  breakdown is sourced from tick sampling and adjusted to the usage
  using cputime_adjust().

This keeps the accounting side hot path O(1) and per-cpu and the read
side O(nr_updated_since_last_read).

v2: Minor changes and documentation updates as suggested by Waiman and
    Roman.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Roman Gushchin <guro@fb.com>
2017-09-25 08:12:05 -07:00
Waiman Long c4fa6c43ce cgroup: Reinit cgroup_taskset structure before cgroup_migrate_execute() returns
The cgroup_taskset structure within the larger cgroup_mgctx structure
is supposed to be used once and then discarded. That is not really the
case in the hotplug code path:

cpuset_hotplug_workfn()
 - cgroup_transfer_tasks()
   - cgroup_migrate()
     - cgroup_migrate_add_task()
     - cgroup_migrate_execute()

In this case, the cgroup_migrate() function is called multiple time
with the same cgroup_mgctx structure to transfer the tasks from
one cgroup to another one-by-one. The second time cgroup_migrate()
is called, the cgroup_taskset will be in an incorrect state and so
may cause the system to panic. For example,

  [  150.888410] Faulting instruction address: 0xc0000000001db648
  [  150.888414] Oops: Kernel access of bad area, sig: 11 [#1]
  [  150.888417] SMP NR_CPUS=2048
  [  150.888417] NUMA
  [  150.888419] pSeries
    :
  [  150.888545] NIP [c0000000001db648] cpuset_can_attach+0x58/0x1b0
  [  150.888548] LR [c0000000001db638] cpuset_can_attach+0x48/0x1b0
  [  150.888551] Call Trace:
  [  150.888554] [c0000005f65cb940] [c0000000001db638] cpuset_can_attach+0x48/0x1b 0 (unreliable)
  [  150.888559] [c0000005f65cb9a0] [c0000000001cff04] cgroup_migrate_execute+0xc4/0x4b0
  [  150.888563] [c0000005f65cba20] [c0000000001d7d14] cgroup_transfer_tasks+0x1d4/0x370
  [  150.888568] [c0000005f65cbb70] [c0000000001ddcb0] cpuset_hotplug_workfn+0x710/0x8f0
  [  150.888572] [c0000005f65cbc80] [c00000000012032c] process_one_work+0x1ac/0x4d0
  [  150.888576] [c0000005f65cbd20] [c0000000001206f8] worker_thread+0xa8/0x5b0
  [  150.888580] [c0000005f65cbdc0] [c0000000001293f8] kthread+0x168/0x1b0
  [  150.888584] [c0000005f65cbe30] [c00000000000b368] ret_from_kernel_thread+0x5c/0x74

To allow reuse of the cgroup_mgctx structure, some fields in that
structure are now re-initialized at the end of cgroup_migrate_execute()
function call so that the structure can be reused again in a later
iteration without causing problem.

This bug was introduced in the commit e595cd7069 ("group: track
migration context in cgroup_mgctx") in 4.11. This commit moves the
cgroup_taskset initialization out of cgroup_migrate(). The commit
10467270fb3 ("cgroup: don't call migration methods if there are no
tasks to migrate") helped, but did not completely resolve the problem.

Fixes: e595cd7069 ("group: track migration context in cgroup_mgctx")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v4.11+
2017-09-22 08:14:45 -07:00
Linus Torvalds 040b9d7ccf Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Three fixes:

   - fix a suspend/resume cpusets bug

   - fix a !CONFIG_NUMA_BALANCING bug

   - fix a kerneldoc warning"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix nuisance kernel-doc warning
  sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs
  sched/fair: Fix wake_affine_llc() balancing rules
2017-09-12 11:30:56 -07:00
Linus Torvalds a0725ab0c7 Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block
Pull block layer updates from Jens Axboe:
 "This is the first pull request for 4.14, containing most of the code
  changes. It's a quiet series this round, which I think we needed after
  the churn of the last few series. This contains:

   - Fix for a registration race in loop, from Anton Volkov.

   - Overflow complaint fix from Arnd for DAC960.

   - Series of drbd changes from the usual suspects.

   - Conversion of the stec/skd driver to blk-mq. From Bart.

   - A few BFQ improvements/fixes from Paolo.

   - CFQ improvement from Ritesh, allowing idling for group idle.

   - A few fixes found by Dan's smatch, courtesy of Dan.

   - A warning fixup for a race between changing the IO scheduler and
     device remova. From David Jeffery.

   - A few nbd fixes from Josef.

   - Support for cgroup info in blktrace, from Shaohua.

   - Also from Shaohua, new features in the null_blk driver to allow it
     to actually hold data, among other things.

   - Various corner cases and error handling fixes from Weiping Zhang.

   - Improvements to the IO stats tracking for blk-mq from me. Can
     drastically improve performance for fast devices and/or big
     machines.

   - Series from Christoph removing bi_bdev as being needed for IO
     submission, in preparation for nvme multipathing code.

   - Series from Bart, including various cleanups and fixes for switch
     fall through case complaints"

* 'for-4.14/block' of git://git.kernel.dk/linux-block: (162 commits)
  kernfs: checking for IS_ERR() instead of NULL
  drbd: remove BIOSET_NEED_RESCUER flag from drbd_{md_,}io_bio_set
  drbd: Fix allyesconfig build, fix recent commit
  drbd: switch from kmalloc() to kmalloc_array()
  drbd: abort drbd_start_resync if there is no connection
  drbd: move global variables to drbd namespace and make some static
  drbd: rename "usermode_helper" to "drbd_usermode_helper"
  drbd: fix race between handshake and admin disconnect/down
  drbd: fix potential deadlock when trying to detach during handshake
  drbd: A single dot should be put into a sequence.
  drbd: fix rmmod cleanup, remove _all_ debugfs entries
  drbd: Use setup_timer() instead of init_timer() to simplify the code.
  drbd: fix potential get_ldev/put_ldev refcount imbalance during attach
  drbd: new disk-option disable-write-same
  drbd: Fix resource role for newly created resources in events2
  drbd: mark symbols static where possible
  drbd: Send P_NEG_ACK upon write error in protocol != C
  drbd: add explicit plugging when submitting batches
  drbd: change list_for_each_safe to while(list_first_entry_or_null)
  drbd: introduce drbd_recv_header_maybe_unplug
  ...
2017-09-07 11:59:42 -07:00
Peter Zijlstra 50e7663233 sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs
Cpusets vs. suspend-resume is _completely_ broken. And it got noticed
because it now resulted in non-cpuset usage breaking too.

On suspend cpuset_cpu_inactive() doesn't call into
cpuset_update_active_cpus() because it doesn't want to move tasks about,
there is no need, all tasks are frozen and won't run again until after
we've resumed everything.

But this means that when we finally do call into
cpuset_update_active_cpus() after resuming the last frozen cpu in
cpuset_cpu_active(), the top_cpuset will not have any difference with
the cpu_active_mask and this it will not in fact do _anything_.

So the cpuset configuration will not be restored. This was largely
hidden because we would unconditionally create identity domains and
mobile users would not in fact use cpusets much. And servers what do use
cpusets tend to not suspend-resume much.

An addition problem is that we'd not in fact wait for the cpuset work to
finish before resuming the tasks, allowing spurious migrations outside
of the specified domains.

Fix the rebuild by introducing cpuset_force_rebuild() and fix the
ordering with cpuset_wait_for_hotplug().

Reported-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: deb7aa308e ("cpuset: reorganize CPU / memory hotplug handling")
Link: http://lkml.kernel.org/r/20170907091338.orwxrqkbfkki3c24@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-07 11:45:21 +02:00
Linus Torvalds 608c1d3c17 Merge branch 'for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "Several notable changes this cycle:

   - Thread mode was merged. This will be used for cgroup2 support for
     CPU and possibly other controllers. Unfortunately, CPU controller
     cgroup2 support didn't make this pull request but most contentions
     have been resolved and the support is likely to be merged before
     the next merge window.

   - cgroup.stat now shows the number of descendant cgroups.

   - cpuset now can enable the easier-to-configure v2 behavior on v1
     hierarchy"

* 'for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits)
  cpuset: Allow v2 behavior in v1 cgroup
  cgroup: Add mount flag to enable cpuset to use v2 behavior in v1 cgroup
  cgroup: remove unneeded checks
  cgroup: misc changes
  cgroup: short-circuit cset_cgroup_from_root() on the default hierarchy
  cgroup: re-use the parent pointer in cgroup_destroy_locked()
  cgroup: add cgroup.stat interface with basic hierarchy stats
  cgroup: implement hierarchy limits
  cgroup: keep track of number of descent cgroups
  cgroup: add comment to cgroup_enable_threaded()
  cgroup: remove unnecessary empty check when enabling threaded mode
  cgroup: update debug controller to print out thread mode information
  cgroup: implement cgroup v2 thread support
  cgroup: implement CSS_TASK_ITER_THREADED
  cgroup: introduce cgroup->dom_cgrp and threaded css_set handling
  cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS
  cgroup: reorganize cgroup.procs / task write path
  cgroup: replace css_set walking populated test with testing cgrp->nr_populated_csets
  cgroup: distinguish local and children populated states
  cgroup: remove now unused list_head @pending in cgroup_apply_cftypes()
  ...
2017-09-06 22:25:25 -07:00
Michal Hocko da99ecf117 mm: replace TIF_MEMDIE checks by tsk_is_oom_victim
TIF_MEMDIE is set only to the tasks whick were either directly selected
by the OOM killer or passed through mark_oom_victim from the allocator
path.  tsk_is_oom_victim is more generic and allows to identify all
tasks (threads) which share the mm with the oom victim.

Please note that the freezer still needs to check TIF_MEMDIE because we
cannot thaw tasks which do not participage in oom_victims counting
otherwise a !TIF_MEMDIE task could interfere after oom_disbale returns.

Link: http://lkml.kernel.org/r/20170810075019.28998-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06 17:27:30 -07:00
Roman Gushchin 65f3975f35 cgroup: revert fa06235b8e ("cgroup: reset css on destruction")
Commit fa06235b8e ("cgroup: reset css on destruction") caused
css_reset callback to be called from the offlining path.  Although it
solves the problem mentioned in the commit description ("For instance,
memory cgroup needs to reset memory.low, otherwise pages charged to a
dead cgroup might never get reclaimed."), generally speaking, it's not
correct.

An offline cgroup can still be a resource domain, and we shouldn't grant
it more resources than it had before deletion.

For instance, if an offline memory cgroup has dirty pages, we should
still imply i/o limits during writeback.

The css_reset callback is designed to return the cgroup state into the
original state, that means reset all limits and counters.  It's
spomething different from the offlining, and we shouldn't use it from
the offlining path.  Instead, we should adjust necessary settings from
the per-controller css_offline callbacks (e.g.  reset memory.low).

Link: http://lkml.kernel.org/r/20170727130428.28856-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-09-06 17:27:27 -07:00
Linus Torvalds 5f82e71a00 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:

 - Add 'cross-release' support to lockdep, which allows APIs like
   completions, where it's not the 'owner' who releases the lock, to be
   tracked. It's all activated automatically under
   CONFIG_PROVE_LOCKING=y.

 - Clean up (restructure) the x86 atomics op implementation to be more
   readable, in preparation of KASAN annotations. (Dmitry Vyukov)

 - Fix static keys (Paolo Bonzini)

 - Add killable versions of down_read() et al (Kirill Tkhai)

 - Rework and fix jump_label locking (Marc Zyngier, Paolo Bonzini)

 - Rework (and fix) tlb_flush_pending() barriers (Peter Zijlstra)

 - Remove smp_mb__before_spinlock() and convert its usages, introduce
   smp_mb__after_spinlock() (Peter Zijlstra)

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
  locking/lockdep/selftests: Fix mixed read-write ABBA tests
  sched/completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK()
  acpi/nfit: Fix COMPLETION_INITIALIZER_ONSTACK() abuse
  locking/pvqspinlock: Relax cmpxchg's to improve performance on some architectures
  smp: Avoid using two cache lines for struct call_single_data
  locking/lockdep: Untangle xhlock history save/restore from task independence
  locking/refcounts, x86/asm: Disable CONFIG_ARCH_HAS_REFCOUNT for the time being
  futex: Remove duplicated code and fix undefined behaviour
  Documentation/locking/atomic: Finish the document...
  locking/lockdep: Fix workqueue crossrelease annotation
  workqueue/lockdep: 'Fix' flush_work() annotation
  locking/lockdep/selftests: Add mixed read-write ABBA tests
  mm, locking/barriers: Clarify tlb_flush_pending() barriers
  locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS truly non-interactive
  locking/lockdep: Explicitly initialize wq_barrier::done::map
  locking/lockdep: Rename CONFIG_LOCKDEP_COMPLETE to CONFIG_LOCKDEP_COMPLETIONS
  locking/lockdep: Reword title of LOCKDEP_CROSSRELEASE config
  locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE part of CONFIG_PROVE_LOCKING
  locking/refcounts, x86/asm: Implement fast refcount overflow protection
  locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease
  ...
2017-09-04 11:52:29 -07:00
Linus Torvalds f213a6c84c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - fix affine wakeups (Peter Zijlstra)

   - improve CPU onlining (and general bootup) scalability on systems
     with ridiculous number (thousands) of CPUs (Peter Zijlstra)

   - sched/numa updates (Rik van Riel)

   - sched/deadline updates (Byungchul Park)

   - sched/cpufreq enhancements and related cleanups (Viresh Kumar)

   - sched/debug enhancements (Xie XiuQi)

   - various fixes"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
  sched/debug: Optimize sched_domain sysctl generation
  sched/topology: Avoid pointless rebuild
  sched/topology, cpuset: Avoid spurious/wrong domain rebuilds
  sched/topology: Improve comments
  sched/topology: Fix memory leak in __sdt_alloc()
  sched/completion: Document that reinit_completion() must be called after complete_all()
  sched/autogroup: Fix error reporting printk text in autogroup_create()
  sched/fair: Fix wake_affine() for !NUMA_BALANCING
  sched/debug: Intruduce task_state_to_char() helper function
  sched/debug: Show task state in /proc/sched_debug
  sched/debug: Use task_pid_nr_ns in /proc/$pid/sched
  sched/core: Remove unnecessary initialization init_idle_bootup_task()
  sched/deadline: Change return value of cpudl_find()
  sched/deadline: Make find_later_rq() choose a closer CPU in topology
  sched/numa: Scale scan period with tasks in group and shared/private
  sched/numa: Slow down scan rate if shared faults dominate
  sched/pelt: Fix false running accounting
  sched: Mark pick_next_task_dl() and build_sched_domain() as static
  sched/cpupri: Don't re-initialize 'struct cpupri'
  sched/deadline: Don't re-initialize 'struct cpudl'
  ...
2017-09-04 09:10:24 -07:00
Ingo Molnar edc2988c54 Merge branch 'linus' into locking/core, to fix up conflicts
Conflicts:
	mm/page_alloc.c

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-04 11:01:18 +02:00
Linus Torvalds 36fde05f3f Merge branch 'for-4.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fix from Tejun Heo:
 "A late but obvious fix for cgroup.

  I broke the 'cpuset.memory_pressure' file a long time ago (v4.4) by
  accidentally deleting its file index, which made it a duplicate of the
  'cpuset.memory_migrate' file. Spotted and fixed by Waiman"

* 'for-4.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset: Fix incorrect memory_pressure control file mapping
2017-08-29 11:16:21 -07:00
Peter Zijlstra 77d1dfda0e sched/topology, cpuset: Avoid spurious/wrong domain rebuilds
When disabling cpuset.sched_load_balance we expect to be able to online
CPUs without generating sched_domains. However this is currently
completely broken.

What happens is that we generate the sched_domains and then destroy
them. This is because of the spurious 'default' domain build in
cpuset_update_active_cpus(). That builds a single machine wide domain
and then schedules a work to build the 'real' domains. The work then
finds there are _no_ domains and destroys the lot again.

Furthermore, if there actually were cpusets, building the machine wide
domain is actively wrong, because it would allow tasks to 'escape' their
cpuset. Also I don't think its needed, the scheduler really should
respect the active mask.

Reported-by: Ofer Levi(SW) <oferle@mellanox.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineet.Gupta1@synopsys.com <Vineet.Gupta1@synopsys.com>
Cc: rusty@rustcorp.com.au <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-25 11:12:20 +02:00
Waiman Long 1c08c22c87 cpuset: Fix incorrect memory_pressure control file mapping
The memory_pressure control file was incorrectly set up without
a private value (0, by default). As a result, this control
file was treated like memory_migrate on read. By adding back the
FILE_MEMORY_PRESSURE private value, the correct memory pressure value
will be returned.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 7dbdb199d3 ("cgroup: replace cftype->mode with CFTYPE_WORLD_WRITABLE")
Cc: stable@vger.kernel.org # v4.4+
2017-08-24 09:42:28 -07:00
Waiman Long b8d1b8ee93 cpuset: Allow v2 behavior in v1 cgroup
Cpuset v2 has some useful behaviors that are not present in v1 because
of backward compatibility concern. One of that is the restoration of
the original cpu and memory node mask after a hot removal and addition
event sequence.

This patch makes the cpuset controller to check the
CGRP_ROOT_CPUSET_V2_MODE flag and use the v2 behavior if it is set.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-08-18 08:24:22 -07:00
Waiman Long e1cba4b85d cgroup: Add mount flag to enable cpuset to use v2 behavior in v1 cgroup
A new mount option "cpuset_v2_mode" is added to the v1 cgroupfs
filesystem to enable cpuset controller to use v2 behavior in a v1
cgroup. This mount option applies only to cpuset controller and have
no effect on other controllers.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-08-18 08:24:21 -07:00
Dan Carpenter 696b98f244 cgroup: remove unneeded checks
"descendants" and "depth" are declared as int, so they can't be larger
than INT_MAX.  Static checkers complain and it's slightly confusing for
humans as well so let's just remove these conditions.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-08-11 10:33:28 -07:00
Tejun Heo 3e48930cc7 cgroup: misc changes
Misc trivial changes to prepare for future changes.  No functional
difference.

* Expose cgroup_get(), cgroup_tryget() and cgroup_parent().

* Implement task_dfl_cgroup() which dereferences css_set->dfl_cgrp.

* Rename cgroup_stats_show() to cgroup_stat_show() for consistency
  with the file name.

Signed-off-by: Tejun Heo <tj@kernel.org>
2017-08-11 05:49:01 -07:00
Paolo Bonzini be040bea90 cpuset: Make nr_cpusets private
Any use of key->enabled (that is static_key_enabled and static_key_count)
outside jump_label_lock should handle its own serialization.  In the case
of cpusets_enabled_key, the key is always incremented/decremented under
cpuset_mutex, and hence the same rule applies to nr_cpusets.  The rule
*is* respected currently, but the mutex is static so nr_cpusets should
be static too.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Zefan Li <lizefan@huawei.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1501601046-35683-4-git-send-email-pbonzini@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 12:28:57 +02:00
Dima Zavin 89affbf5d9 cpuset: fix a deadlock due to incomplete patching of cpusets_enabled()
In codepaths that use the begin/retry interface for reading
mems_allowed_seq with irqs disabled, there exists a race condition that
stalls the patch process after only modifying a subset of the
static_branch call sites.

This problem manifested itself as a deadlock in the slub allocator,
inside get_any_partial.  The loop reads mems_allowed_seq value (via
read_mems_allowed_begin), performs the defrag operation, and then
verifies the consistency of mem_allowed via the read_mems_allowed_retry
and the cookie returned by xxx_begin.

The issue here is that both begin and retry first check if cpusets are
enabled via cpusets_enabled() static branch.  This branch can be
rewritted dynamically (via cpuset_inc) if a new cpuset is created.  The
x86 jump label code fully synchronizes across all CPUs for every entry
it rewrites.  If it rewrites only one of the callsites (specifically the
one in read_mems_allowed_retry) and then waits for the
smp_call_function(do_sync_core) to complete while a CPU is inside the
begin/retry section with IRQs off and the mems_allowed value is changed,
we can hang.

This is because begin() will always return 0 (since it wasn't patched
yet) while retry() will test the 0 against the actual value of the seq
counter.

The fix is to use two different static keys: one for begin
(pre_enable_key) and one for retry (enable_key).  In cpuset_inc(), we
first bump the pre_enable key to ensure that cpuset_mems_allowed_begin()
always return a valid seqcount if are enabling cpusets.  Similarly, when
disabling cpusets via cpuset_dec(), we first ensure that callers of
cpuset_mems_allowed_retry() will start ignoring the seqcount value
before we let cpuset_mems_allowed_begin() return 0.

The relevant stack traces of the two stuck threads:

  CPU: 1 PID: 1415 Comm: mkdir Tainted: G L  4.9.36-00104-g540c51286237 #4
  Hardware name: Default string Default string/Hardware, BIOS 4.29.1-20170526215256 05/26/2017
  task: ffff8817f9c28000 task.stack: ffffc9000ffa4000
  RIP: smp_call_function_many+0x1f9/0x260
  Call Trace:
    smp_call_function+0x3b/0x70
    on_each_cpu+0x2f/0x90
    text_poke_bp+0x87/0xd0
    arch_jump_label_transform+0x93/0x100
    __jump_label_update+0x77/0x90
    jump_label_update+0xaa/0xc0
    static_key_slow_inc+0x9e/0xb0
    cpuset_css_online+0x70/0x2e0
    online_css+0x2c/0xa0
    cgroup_apply_control_enable+0x27f/0x3d0
    cgroup_mkdir+0x2b7/0x420
    kernfs_iop_mkdir+0x5a/0x80
    vfs_mkdir+0xf6/0x1a0
    SyS_mkdir+0xb7/0xe0
    entry_SYSCALL_64_fastpath+0x18/0xad

  ...

  CPU: 2 PID: 1 Comm: init Tainted: G L  4.9.36-00104-g540c51286237 #4
  Hardware name: Default string Default string/Hardware, BIOS 4.29.1-20170526215256 05/26/2017
  task: ffff8818087c0000 task.stack: ffffc90000030000
  RIP: int3+0x39/0x70
  Call Trace:
    <#DB> ? ___slab_alloc+0x28b/0x5a0
    <EOE> ? copy_process.part.40+0xf7/0x1de0
    __slab_alloc.isra.80+0x54/0x90
    copy_process.part.40+0xf7/0x1de0
    copy_process.part.40+0xf7/0x1de0
    kmem_cache_alloc_node+0x8a/0x280
    copy_process.part.40+0xf7/0x1de0
    _do_fork+0xe7/0x6c0
    _raw_spin_unlock_irq+0x2d/0x60
    trace_hardirqs_on_caller+0x136/0x1d0
    entry_SYSCALL_64_fastpath+0x5/0xad
    do_syscall_64+0x27/0x350
    SyS_clone+0x19/0x20
    do_syscall_64+0x60/0x350
    entry_SYSCALL64_slow_path+0x25/0x25

Link: http://lkml.kernel.org/r/20170731040113.14197-1-dmitriyz@waymo.com
Fixes: 46e700abc4 ("mm, page_alloc: remove unnecessary taking of a seqlock when cpusets are disabled")
Signed-off-by: Dima Zavin <dmitriyz@waymo.com>
Reported-by: Cliff Spradlin <cspradlin@waymo.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-08-02 17:16:12 -07:00
Tejun Heo 13d82fb77a cgroup: short-circuit cset_cgroup_from_root() on the default hierarchy
Each css_set directly points to the default cgroup it belongs to, so
there's no reason to walk the cgrp_links list on the default
hierarchy.

Signed-off-by: Tejun Heo <tj@kernel.org>
2017-08-02 15:39:38 -07:00
Roman Gushchin 5a621e6c95 cgroup: re-use the parent pointer in cgroup_destroy_locked()
As we already have a pointer to the parent cgroup in
cgroup_destroy_locked(), we don't need to calculate it again
to pass as an argument for cgroup1_check_for_release().

Signed-off-by: Roman Gushchin <guro@fb.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: kernel-team@fb.com
Cc: linux-kernel@vger.kernel.org
2017-08-02 12:05:20 -07:00
Roman Gushchin ec39225cca cgroup: add cgroup.stat interface with basic hierarchy stats
A cgroup can consume resources even after being deleted by a user.
For example, writing back dirty pages should be accounted and
limited, despite the corresponding cgroup might contain no processes
and being deleted by a user.

In the current implementation a cgroup can remain in such "dying" state
for an undefined amount of time. For instance, if a memory cgroup
contains a pge, mlocked by a process belonging to an other cgroup.

Although the lifecycle of a dying cgroup is out of user's control,
it's important to have some insight of what's going on under the hood.

In particular, it's handy to have a counter which will allow
to detect css leaks.

To solve this problem, add a cgroup.stat interface to
the base cgroup control files with the following metrics:

nr_descendants		total number of visible descendant cgroups
nr_dying_descendants	total number of dying descendant cgroups

Signed-off-by: Roman Gushchin <guro@fb.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: kernel-team@fb.com
Cc: cgroups@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
2017-08-02 12:05:20 -07:00