a tasks "comm" field. But this prevented filtering on a comm field that
is within a trace event (like sched_migrate_task).
When trying to filter on when a program migrated, this change prevented
the filtering of the sched_migrate_task.
To fix this, the event fields are examined first, and then the extra fields
like "comm" and "cpu" are examined. Also, instead of testing to assign
the comm filter function based on the field's name, the generic comm field
is given a new filter type (FILTER_COMM). When this field is used to filter
the type is checked. The same is done for the cpu filter field.
Two new special filter types are added: "COMM" and "CPU". This allows users
to still filter the tasks comm for events that have "comm" as one of their
fields, in cases that users would like to filter sched_migrate_task on the
comm of the task that called the event, and not the comm of the task that
is being migrated.
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Merge tag 'trace-fixes-v4.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
"A feature was added in 4.3 that allowed users to filter trace points
on a tasks "comm" field. But this prevented filtering on a comm field
that is within a trace event (like sched_migrate_task).
When trying to filter on when a program migrated, this change
prevented the filtering of the sched_migrate_task.
To fix this, the event fields are examined first, and then the extra
fields like "comm" and "cpu" are examined. Also, instead of testing
to assign the comm filter function based on the field's name, the
generic comm field is given a new filter type (FILTER_COMM). When
this field is used to filter the type is checked. The same is done
for the cpu filter field.
Two new special filter types are added: "COMM" and "CPU". This allows
users to still filter the tasks comm for events that have "comm" as
one of their fields, in cases that users would like to filter
sched_migrate_task on the comm of the task that called the event, and
not the comm of the task that is being migrated"
* tag 'trace-fixes-v4.5-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Do not have 'comm' filter override event 'comm' field
Commit 9f61668073 "tracing: Allow triggers to filter for CPU ids and
process names" added a 'comm' filter that will filter events based on the
current tasks struct 'comm'. But this now hides the ability to filter events
that have a 'comm' field too. For example, sched_migrate_task trace event.
That has a 'comm' field of the task to be migrated.
echo 'comm == "bash"' > events/sched_migrate_task/filter
will now filter all sched_migrate_task events for tasks named "bash" that
migrates other tasks (in interrupt context), instead of seeing when "bash"
itself gets migrated.
This fix requires a couple of changes.
1) Change the look up order for filter predicates to look at the events
fields before looking at the generic filters.
2) Instead of basing the filter function off of the "comm" name, have the
generic "comm" filter have its own filter_type (FILTER_COMM). Test
against the type instead of the name to assign the filter function.
3) Add a new "COMM" filter that works just like "comm" but will filter based
on the current task, even if the trace event contains a "comm" field.
Do the same for "cpu" field, adding a FILTER_CPU and a filter "CPU".
Cc: stable@vger.kernel.org # v4.3+
Fixes: 9f61668073 "tracing: Allow triggers to filter for CPU ids and process names"
Reported-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As Jiri pointed out, this recent commit:
f872f5400c ("mm: Add a vm_special_mapping.fault() method")
breaks uprobes: __create_xol_area() doesn't initialize the new ->fault()
method and this obviously leads to kernel crash when the application
tries to execute the probed insn after bp hit.
We probably want to add uprobes_special_mapping_fault(), this allows to
turn xol_area->xol_mapping into a single instance of vm_special_mapping.
But we need a simple fix, so lets change __create_xol() to nullify the
new member as Jiri suggests.
Suggested-by: Jiri Olsa <jolsa@redhat.com>
Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <tipbot@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160227221128.GA29565@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull perf fixes from Thomas Gleixner:
"A rather largish series of 12 patches addressing a maze of race
conditions in the perf core code from Peter Zijlstra"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Robustify task_function_call()
perf: Fix scaling vs. perf_install_in_context()
perf: Fix scaling vs. perf_event_enable()
perf: Fix scaling vs. perf_event_enable_on_exec()
perf: Fix ctx time tracking by introducing EVENT_TIME
perf: Cure event->pending_disable race
perf: Fix race between event install and jump_labels
perf: Fix cloning
perf: Only update context time when active
perf: Allow perf_release() with !event->ctx
perf: Do not double free
perf: Close install vs. exit race
Pull scheduler fixlet from Thomas Gleixner:
"A trivial printk typo fix"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/deadline: Fix trivial typo in printk() message
When perf added a "reg" function to the function tracing event (not a
tracepoint), it caused that event to be displayed as a tracepoint and
could cause errors in tracepoint handling. That was solved by adding a
flag to ignore ftrace non-tracepoint events. But that flag was missed
when displaying events in available_events, which should only contain
tracepoint events.
This broke a documented way to enable all events with:
cat available_events > set_event
As the function non-tracepoint event would cause that to error out.
The commit here fixes that by having the available_events file not list
events that have the ignore flag set.
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Merge tag 'trace-fixes-v4.5-rc5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
"Another small bug reported to me by Chunyu Hu.
When perf added a "reg" function to the function tracing event (not a
tracepoint), it caused that event to be displayed as a tracepoint and
could cause errors in tracepoint handling. That was solved by adding
a flag to ignore ftrace non-tracepoint events. But that flag was
missed when displaying events in available_events, which should only
contain tracepoint events.
This broke a documented way to enable all events with:
cat available_events > set_event
As the function non-tracepoint event would cause that to error out.
The commit here fixes that by having the available_events file not
list events that have the ignore flag set"
* tag 'trace-fixes-v4.5-rc5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix showing function event in available_events
Pull libnvdimm fixes from Dan Williams:
- Two fixes for compatibility with the ACPI 6.1 specification.
Without these fixes multi-interface DIMMs will fail to be probed, and
address range scrub commands to find memory errors will give results
that the kernel will mis-interpret. For multi-interface DIMMs Linux
will accept either the original 6.0 implementation or 6.1.
For address range scrub we'll only support 6.1 since ACPI formalized
this DSM differently than the original example [1] implemented in
v4.2. The expectation is that production systems will only ever ship
the ACPI 6.1 address range scrub command definition.
- The wider async address range scrub work targeting 4.6 discovered
that the original synchronous implementation in 4.5 is not sizing its
return buffer correctly.
- Arnd caught that my recent fix to the size of the pfn_t flags missed
updating the flags variable used in the pmem driver.
- Toshi found that we mishandle the memremap() return value in
devm_memremap().
* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
nvdimm: use 'u64' for pfn flags
devm_memremap: Fix error value when memremap failed
nfit: update address range scrub commands to the acpi 6.1 format
libnvdimm, tools/testing/nvdimm: fix 'ars_status' output buffer sizing
nfit: fix multi-interface dimm handling, acpi6.1 compatibility
Since there is no serialization between task_function_call() doing
task_curr() and the other CPU doing context switches, we could end
up not sending an IPI even if we had to.
And I'm not sure I still buy my own argument we're OK.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.340031200@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Completely reworks perf_install_in_context() (again!) in order to
ensure that there will be no ctx time hole between add_event_to_ctx()
and any potential ctx_sched_in().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.279399438@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The recent commit 3e349507d1 ("perf: Fix perf_enable_on_exec() event
scheduling") caused this by moving task_ctx_sched_out() from before
__perf_event_mask_enable() to after it.
The overlooked consequence of that change is that task_ctx_sched_out()
would update the ctx time fields, and now __perf_event_mask_enable()
uses stale time.
In order to fix this, explicitly stop our context's time before
enabling the event(s).
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Fixes: 3e349507d1 ("perf: Fix perf_enable_on_exec() event scheduling")
Link: http://lkml.kernel.org/r/20160224174948.159242158@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently any ctx_sched_in() call will re-start the ctx time tracking,
this means that calls like:
ctx_sched_in(.event_type = EVENT_PINNED);
ctx_sched_in(.event_type = EVENT_FLEXIBLE);
will have a hole in their ctx time tracking. This is likely harmless
but can confuse things a little. By adding EVENT_TIME, we can have the
first ctx_sched_in() (is_active: 0 -> !0) start the time and any
further ctx_sched_in() will leave the timestamps alone.
Secondly, this allows for an early disable like:
ctx_sched_out(.event_type = EVENT_TIME);
which would update the ctx time (if the ctx is active) and any further
calls to ctx_sched_out() would not further modify the ctx time.
For ctx_sched_in() any 0 -> !0 transition will automatically include
EVENT_TIME.
For ctx_sched_out(), any transition that clears EVENT_ALL will
automatically clear EVENT_TIME.
These two rules ensure that under normal circumstances we need not
bother with EVENT_TIME and get natural ctx time behaviour.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.100446561@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Because event_sched_out() checks event->pending_disable _before_
actually disabling the event, it can happen that the event fires after
it checks but before it gets disabled.
This would leave event->pending_disable set and the queued irq_work
will try and process it.
However, if the event trigger was during schedule(), the event might
have been de-scheduled by the time the irq_work runs, and
perf_event_disable_local() will fail.
Fix this by checking event->pending_disable _after_ we call
event->pmu->del(). This depends on the latter being a compiler
barrier, such that the compiler does not lift the load and re-creates
the problem.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174948.040469884@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
perf_install_in_context() relies upon the context switch hooks to have
scheduled in events when the IPI misses its target -- after all, if
the task has moved from the CPU (or wasn't running at all), it will
have to context switch to run elsewhere.
This however doesn't appear to be happening.
It is possible for the IPI to not happen (task wasn't running) only to
later observe the task running with an inactive context.
The only possible explanation is that the context switch hooks are not
called. Therefore put in a sync_sched() after toggling the jump_label
to guarantee all CPUs will have them enabled before we install an
event.
A simple if (0->1) sync_sched() will not in fact work, because any
further increment can race and complete before the sync_sched().
Therefore we must jump through some hoops.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.980211985@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Alexander reported that when the 'original' context gets destroyed, no
new clones happen.
This can happen irrespective of the ctx switch optimization, any task
can die, even the parent, and we want to continue monitoring the task
hierarchy until we either close the event or no tasks are left in the
hierarchy.
perf_event_init_context() will attempt to pin the 'parent' context
during clone(). At that point current is the parent, and since current
cannot have exited while executing clone(), its context cannot have
passed through perf_event_exit_task_context(). Therefore
perf_pin_task_context() cannot observe ctx->task == TASK_TOMBSTONE.
However, since inherit_event() does:
if (parent_event->parent)
parent_event = parent_event->parent;
it looks at the 'original' event when it does: is_orphaned_event().
This can return true if the context that contains the this event has
passed through perf_event_exit_task_context(). And thus we'll fail to
clone the perf context.
Fix this by adding a new state: STATE_DEAD, which is set by
perf_release() to indicate that the filedesc (or kernel reference) is
dead and there are no observers for our data left.
Only for STATE_DEAD will is_orphaned_event() be true and inhibit
cloning.
STATE_EXIT is otherwise preserved such that is_event_hup() remains
functional and will report when the observed task hierarchy becomes
empty.
Reported-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Fixes: c6e5b73242 ("perf: Synchronously clean up child events")
Link: http://lkml.kernel.org/r/20160224174947.919845295@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the err_file: fput(event_file) case, the event will not yet have
been attached to a context. However perf_release() does assume it has
been. Cure this.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.793996260@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In case of: err_file: fput(event_file), we'll end up calling
perf_release() which in turn will free the event.
Do not then free the event _again_.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.697350349@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Consider the following scenario:
CPU0 CPU1
ctx = find_get_ctx();
perf_event_exit_task_context()
mutex_lock(&ctx->mutex);
perf_install_in_context(ctx, ...);
/* NO-OP */
mutex_unlock(&ctx->mutex);
...
perf_release()
WARN_ON_ONCE(event->state != STATE_EXIT);
Since the event doesn't pass through perf_remove_from_context()
because perf_install_in_context() NO-OPs because the ctx is dead, and
perf_event_exit_task_context() will not observe the event because its
not attached yet, the event->state will not be set.
Solve this by revalidating ctx->task after we acquire ctx->mutex and
failing the event creation as a whole.
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: eranian@google.com
Cc: oleg@redhat.com
Cc: panand@redhat.com
Cc: sasha.levin@oracle.com
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160224174947.626853419@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The ftrace:function event is only displayed for parsing the function tracer
data. It is not used to enable function tracing, and does not include an
"enable" file in its event directory.
Originally, this event was kept separate from other events because it did
not have a ->reg parameter. But perf added a "reg" parameter for its use
which caused issues, because it made the event available to functions where
it was not compatible for.
Commit 9b63776fa3 "tracing: Do not enable function event with enable"
added a TRACE_EVENT_FL_IGNORE_ENABLE flag that prevented the function event
from being enabled by normal trace events. But this commit missed keeping
the function event from being displayed by the "available_events" directory,
which is used to show what events can be enabled by set_event.
One documented way to enable all events is to:
cat available_events > set_event
But because the function event is displayed in the available_events, this
now causes an INVALID error:
cat: write error: Invalid argument
Reported-by: Chunyu Hu <chuhu@redhat.com>
Fixes: 9b63776fa3 "tracing: Do not enable function event with enable"
Cc: stable@vger.kernel.org # 3.4+
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
devm_memremap() returns an ERR_PTR() value in case of error.
However, it returns NULL when memremap() failed. This causes
the caller, such as the pmem driver, to proceed and oops later.
Change devm_memremap() to return ERR_PTR(-ENXIO) when memremap()
failed.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
One is by Yang Shi who added a READ_ONCE_NOCHECK() to the scan of the
stack made by the stack tracer. As the stack tracer scans the entire
kernel stack, KASAN triggers seeing it as a "stack out of bounds" error.
As the scan is looking at the contents of the stack from parent functions.
The NOCHECK() tells KASAN that this is done on purpose, and is not some
kind of stack overflow.
The second fix is to the ftrace selftests, to retrieve the PID of executed
commands from the shell with "$!" and not by parsing "jobs".
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Merge tag 'trace-fixes-v4.5-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
"Two more small fixes.
One is by Yang Shi who added a READ_ONCE_NOCHECK() to the scan of the
stack made by the stack tracer. As the stack tracer scans the entire
kernel stack, KASAN triggers seeing it as a "stack out of bounds"
error. As the scan is looking at the contents of the stack from
parent functions. The NOCHECK() tells KASAN that this is done on
purpose, and is not some kind of stack overflow.
The second fix is to the ftrace selftests, to retrieve the PID of
executed commands from the shell with '$!' and not by parsing 'jobs'"
* tag 'trace-fixes-v4.5-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing, kasan: Silence Kasan warning in check_stack of stack_tracer
ftracetest: Fix instance test to use proper shell command for pids
Pull perf fixes from Ingo Molnar:
"A handful of CPU hotplug related fixes"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/core: Plug potential memory leak in CPU_UP_PREPARE
perf/core: Remove the bogus and dangerous CPU_DOWN_FAILED hotplug state
perf/core: Remove bogus UP_CANCELED hotplug state
perf/x86/amd/uncore: Plug reference leak
In __request_region, if a conflict with a BUSY and MUXED resource is
detected, then the caller goes to sleep and waits for the resource to be
released. A pointer on the conflicting resource is kept. At wake-up
this pointer is used as a parent to retry to request the region.
A first problem is that this pointer might well be invalid (if for
example the conflicting resource have already been freed). Another
problem is that the next call to __request_region() fails to detect a
remaining conflict. The previously conflicting resource is passed as a
parameter and __request_region() will look for a conflict among the
children of this resource and not at the resource itself. It is likely
to succeed anyway, even if there is still a conflict.
Instead, the parent of the conflicting resource should be passed to
__request_region().
As a fix, this patch doesn't update the parent resource pointer in the
case we have to wait for a muxed region right after.
Reported-and-tested-by: Vincent Pelletier <plr.vincent@gmail.com>
Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Tested-by: Vincent Donnefort <vdonnefort@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge fixes from Andrew Morton:
"10 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
mm: slab: free kmem_cache_node after destroy sysfs file
ipc/shm: handle removed segments gracefully in shm_mmap()
MAINTAINERS: update Kselftest Framework mailing list
devm_memremap_release(): fix memremap'd addr handling
mm/hugetlb.c: fix incorrect proc nr_hugepages value
mm, x86: fix pte_page() crash in gup_pte_range()
fsnotify: turn fsnotify reaper thread into a workqueue job
Revert "fsnotify: destroy marks with call_srcu instead of dedicated thread"
mm: fix regression in remap_file_pages() emulation
thp, dax: do not try to withdraw pgtable from non-anon VMA
Pull livepatching fixes from Jiri Kosina:
- regression (from 4.4) fix for ordering issue, introduced by an
earlier ftrace change, that broke live patching of modules.
The fix replaces the ftrace module notifier by direct call in order
to make the ordering guaranteed and well-defined. The patch, from
Jessica Yu, has been acked both by Steven and Rusty
- error message fix from Miroslav Benes
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
ftrace/module: remove ftrace module notifier
livepatch: change the error message in asm/livepatch.h header files
The pmem driver calls devm_memremap() to map a persistent memory range.
When the pmem driver is unloaded, this memremap'd range is not released
so the kernel will leak a vma.
Fix devm_memremap_release() to handle a given memremap'd address
properly.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the ftrace module notifier in favor of directly calling
ftrace_module_enable() and ftrace_release_mod() in the module loader.
Hard-coding the function calls directly in the module loader removes
dependence on the module notifier call chain and provides better
visibility and control over what gets called when, which is important
to kernel utilities such as livepatch.
This fixes a notifier ordering issue in which the ftrace module notifier
(and hence ftrace_module_enable()) for coming modules was being called
after klp_module_notify(), which caused livepatch modules to initialize
incorrectly. This patch removes dependence on the module notifier call
chain in favor of hard coding the corresponding function calls in the
module loader. This ensures that ftrace and livepatch code get called in
the correct order on patch module load and unload.
Fixes: 5156dca34a ("ftrace: Fix the race between ftrace and insmod")
Signed-off-by: Jessica Yu <jeyu@redhat.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
If CPU_UP_PREPARE is called it is not guaranteed, that a previously allocated
and assigned hash has been freed already, but perf_event_init_cpu()
unconditionally allocates and assignes a new hash if the swhash is referenced.
By overwriting the pointer the existing hash is not longer accessible.
Verify that there is no hash assigned on this cpu before allocating and
assigning a new one.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160209201007.843269966@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If CPU_DOWN_PREPARE fails the perf hotplug notifier is called for
CPU_DOWN_FAILED and calls perf_event_init_cpu(), which checks whether the
swhash is referenced. If yes it allocates a new hash and stores the pointer in
the per cpu data structure.
But at this point the cpu is still online, so there must be a valid hash
already. By overwriting the pointer the existing hash is not longer
accessible.
Remove the CPU_DOWN_FAILED state, as there is nothing to (re)allocate.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160209201007.763417379@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If CPU_UP_PREPARE fails the perf hotplug code calls perf_event_exit_cpu(),
which is a pointless exercise. The cpu is not online, so the smp function
calls return -ENXIO. So the result is a list walk to call noops.
Remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/20160209201007.682184765@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull lockdep fix from Thomas Gleixner:
"A single fix for the stack trace caching logic in lockdep, where the
duplicate avoidance managed to store no back trace at all"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/lockdep: Fix stack trace caching logic
The pfn_t type uses an unsigned long to store a pfn + flags value. On a
64-bit platform the upper 12 bits of an unsigned long are never used for
storing the value of a pfn. However, this is not true on highmem
platforms, all 32-bits of a pfn value are used to address a 44-bit
physical address space. A pfn_t needs to store a 64-bit value.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=112211
Fixes: 01c8f1c44b ("mm, dax, gpu: convert vm_insert_mixed to pfn_t")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Stuart Foster <smf.linux@ntlworld.com>
Reported-by: Julian Margetson <runaway@candw.ms>
Tested-by: Julian Margetson <runaway@candw.ms>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mike said:
: CONFIG_UBSAN_ALIGNMENT breaks x86-64 kernel with lockdep enabled, i. e
: kernel with CONFIG_UBSAN_ALIGNMENT fails to load without even any error
: message.
:
: The problem is that ubsan callbacks use spinlocks and might be called
: before lockdep is initialized. Particularly this line in the
: reserve_ebda_region function causes problem:
:
: lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
:
: If i put lockdep_init() before reserve_ebda_region call in
: x86_64_start_reservations kernel loads well.
Fix this ordering issue permanently: change lockdep so that it uses
hlists for the hash tables. Unlike a list_head, an hlist_head is in its
initialized state when it is all-zeroes, so lockdep is ready for
operation immediately upon boot - lockdep_init() need not have run.
The patch will also save some memory.
lockdep_init() and lockdep_initialized can be done away with now - a 4.6
patch has been prepared to do this.
Reported-by: Mike Krinkin <krinkin.m.u@gmail.com>
Suggested-by: Mike Krinkin <krinkin.m.u@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull networking fixes from David Miller:
1) Fix BPF handling of branch offset adjustmnets on backjumps, from
Daniel Borkmann.
2) Make sure selinux knows about SOCK_DESTROY netlink messages, from
Lorenzo Colitti.
3) Fix openvswitch tunnel mtu regression, from David Wragg.
4) Fix ICMP handling of TCP sockets in syn_recv state, from Eric
Dumazet.
5) Fix SCTP user hmacid byte ordering bug, from Xin Long.
6) Fix recursive locking in ipv6 addrconf, from Subash Abhinov
Kasiviswanathan.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
bpf: fix branch offset adjustment on backjumps after patching ctx expansion
vxlan, gre, geneve: Set a large MTU on ovs-created tunnel devices
geneve: Relax MTU constraints
vxlan: Relax MTU constraints
flow_dissector: Fix unaligned access in __skb_flow_dissector when used by eth_get_headlen
of: of_mdio: Add marvell, 88e1145 to whitelist of PHY compatibilities.
selinux: nlmsgtab: add SOCK_DESTROY to the netlink mapping tables
sctp: translate network order to host order when users get a hmacid
enic: increment devcmd2 result ring in case of timeout
tg3: Fix for tg3 transmit queue 0 timed out when too many gso_segs
net:Add sysctl_max_skb_frags
tcp: do not drop syn_recv on all icmp reports
ipv6: fix a lockdep splat
unix: correctly track in-flight fds in sending process user_struct
update be2net maintainers' email addresses
dwc_eth_qos: Reset hardware before PHY start
ipv6: addrconf: Fix recursive spin lock call
When ctx access is used, the kernel often needs to expand/rewrite
instructions, so after that patching, branch offsets have to be
adjusted for both forward and backward jumps in the new eBPF program,
but for backward jumps it fails to account the delta. Meaning, for
example, if the expansion happens exactly on the insn that sits at
the jump target, it doesn't fix up the back jump offset.
Analysis on what the check in adjust_branches() is currently doing:
/* adjust offset of jmps if necessary */
if (i < pos && i + insn->off + 1 > pos)
insn->off += delta;
else if (i > pos && i + insn->off + 1 < pos)
insn->off -= delta;
First condition (forward jumps):
Before: After:
insns[0] insns[0]
insns[1] <--- i/insn insns[1] <--- i/insn
insns[2] <--- pos insns[P] <--- pos
insns[3] insns[P] `------| delta
insns[4] <--- target_X insns[P] `-----|
insns[5] insns[3]
insns[4] <--- target_X
insns[5]
First case is if we cross pos-boundary and the jump instruction was
before pos. This is handeled correctly. I.e. if i == pos, then this
would mean our jump that we currently check was the patchlet itself
that we just injected. Since such patchlets are self-contained and
have no awareness of any insns before or after the patched one, the
delta is correctly not adjusted. Also, for the second condition in
case of i + insn->off + 1 == pos, means we jump to that newly patched
instruction, so no offset adjustment are needed. That part is correct.
Second condition (backward jumps):
Before: After:
insns[0] insns[0]
insns[1] <--- target_X insns[1] <--- target_X
insns[2] <--- pos <-- target_Y insns[P] <--- pos <-- target_Y
insns[3] insns[P] `------| delta
insns[4] <--- i/insn insns[P] `-----|
insns[5] insns[3]
insns[4] <--- i/insn
insns[5]
Second interesting case is where we cross pos-boundary and the jump
instruction was after pos. Backward jump with i == pos would be
impossible and pose a bug somewhere in the patchlet, so the first
condition checking i > pos is okay only by itself. However, i +
insn->off + 1 < pos does not always work as intended to trigger the
adjustment. It works when jump targets would be far off where the
delta wouldn't matter. But, for example, where the fixed insn->off
before pointed to pos (target_Y), it now points to pos + delta, so
that additional room needs to be taken into account for the check.
This means that i) both tests here need to be adjusted into pos + delta,
and ii) for the second condition, the test needs to be <= as pos
itself can be a target in the backjump, too.
Fixes: 9bac3d6d54 ("bpf: allow extended BPF programs access skb fields")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull cgroup fixes from Tejun Heo:
- The destruction path of cgroup objects are asynchronous and
multi-staged and some of them ended up destroying parents before
children leading to failures in cpu and memory controllers. Ensure
that parents are always destroyed after children.
- cpuset mm node migration was performed synchronously while holding
threadgroup and cgroup mutexes and the recent threadgroup locking
update resulted in a possible deadlock. The migration is best effort
and shouldn't have been performed under those locks to begin with.
Made asynchronous.
- Minor documentation fix.
* 'for-4.5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
Documentation: cgroup: Fix 'cgroup-legacy' -> 'cgroup-v1'
cgroup: make sure a parent css isn't freed before its children
cgroup: make sure a parent css isn't offlined before its children
cpuset: make mm migration asynchronous
Pull workqueue fixes from Tejun Heo:
"Workqueue fixes for v4.5-rc3.
- Remove a spurious triggering of flush dependency warning.
- Officially break local execution guarantee of unbound work items
and add a debug feature to flush out usages which depend on it.
- Work around CPU -> NODE mapping becoming invalid on CPU offline.
The branch is young but pushing out early as stable kernels are being
affected"
* 'for-4.5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: handle NUMA_NO_NODE for unbound pool_workqueue lookup
workqueue: implement "workqueue.debug_force_rr_cpu" debug feature
workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs
Revert "workqueue: make sure delayed work run in local cpu"
workqueue: skip flush dependency checks for legacy workqueues
When looking up the pool_workqueue to use for an unbound workqueue,
workqueue assumes that the target CPU is always bound to a valid NUMA
node. However, currently, when a CPU goes offline, the mapping is
destroyed and cpu_to_node() returns NUMA_NO_NODE.
This has always been broken but hasn't triggered often enough before
874bbfe600 ("workqueue: make sure delayed work run in local cpu").
After the commit, workqueue forcifully assigns the local CPU for
delayed work items without explicit target CPU to fix a different
issue. This widens the window where CPU can go offline while a
delayed work item is pending causing delayed work items dispatched
with target CPU set to an already offlined CPU. The resulting
NUMA_NO_NODE mapping makes workqueue try to queue the work item on a
NULL pool_workqueue and thus crash.
While 874bbfe600 has been reverted for a different reason making the
bug less visible again, it can still happen. Fix it by mapping
NUMA_NO_NODE to the default pool_workqueue from unbound_pwq_by_node().
This is a temporary workaround. The long term solution is keeping CPU
-> NODE mapping stable across CPU off/online cycles which is being
worked on.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/g/1454424264.11183.46.camel@gmail.com
Link: http://lkml.kernel.org/g/1453702100-2597-1-git-send-email-tangchen@cn.fujitsu.com
and a much more interesting kallsyms race which has been around approximately
forever. This fix is more invasive, and will require some care in backporting,
but I hated all the bandaids I could think of, so...
There are some more coming, which are only for breakages introduced this
cycle (livepatch), but wanted these in now.
Thanks,
Rusty.
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Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull module fixes from Rusty Russell:
"Fix for async_probe module param added in 4.3 (clearly not widely used
yet), and a much more interesting kallsyms race which has been around
approximately forever. This fix is more invasive, and will require
some care in backporting, but I hated all the bandaids I could think
of, so...
There are some more coming, which are only for breakages introduced
this cycle (livepatch), but wanted these in now"
* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
modules: fix longstanding /proc/kallsyms vs module insertion race.
module: wrapper for symbol name.
modules: fix modparam async_probe request
Workqueue used to guarantee local execution for work items queued
without explicit target CPU. The guarantee is gone now which can
break some usages in subtle ways. To flush out those cases, this
patch implements a debug feature which forces round-robin CPU
selection for all such work items.
The debug feature defaults to off and can be enabled with a kernel
parameter. The default can be flipped with a debug config option.
If you hit this commit during bisection, please refer to 041bd12e27
("Revert "workqueue: make sure delayed work run in local cpu"") for
more information and ping me.
Signed-off-by: Tejun Heo <tj@kernel.org>
WORK_CPU_UNBOUND work items queued to a bound workqueue always run
locally. This is a good thing normally, but not when the user has
asked us to keep unbound work away from certain CPUs. Round robin
these to wq_unbound_cpumask CPUs instead, as perturbation avoidance
trumps performance.
tj: Cosmetic and comment changes. WARN_ON_ONCE() dropped from empty
(wq_unbound_cpumask AND cpu_online_mask). If we want that, it
should be done when config changes.
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This reverts commit 874bbfe600.
Workqueue used to implicity guarantee that work items queued without
explicit CPU specified are put on the local CPU. Recent changes in
timer broke the guarantee and led to vmstat breakage which was fixed
by 176bed1de5 ("vmstat: explicitly schedule per-cpu work on the CPU
we need it to run on").
vmstat is the most likely to expose the issue and it's quite possible
that there are other similar problems which are a lot more difficult
to trigger. As a preventive measure, 874bbfe600 ("workqueue: make
sure delayed work run in local cpu") was applied to restore the local
CPU guarnatee. Unfortunately, the change exposed a bug in timer code
which got fixed by 22b886dd10 ("timers: Use proper base migration in
add_timer_on()"). Due to code restructuring, the commit couldn't be
backported beyond certain point and stable kernels which only had
874bbfe600 started crashing.
The local CPU guarantee was accidental more than anything else and we
want to get rid of it anyway. As, with the vmstat case fixed,
874bbfe600 is causing more problems than it's fixing, it has been
decided to take the chance and officially break the guarantee by
reverting the commit. A debug feature will be added to force foreign
CPU assignment to expose cases relying on the guarantee and fixes for
the individual cases will be backported to stable as necessary.
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 874bbfe600 ("workqueue: make sure delayed work run in local cpu")
Link: http://lkml.kernel.org/g/20160120211926.GJ10810@quack.suse.cz
Cc: stable@vger.kernel.org
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Daniel Bilik <daniel.bilik@neosystem.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Shaohua Li <shli@fb.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Daniel Bilik <daniel.bilik@neosystem.cz>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
check_prev_add() caches saved stack trace in static trace variable
to avoid duplicate save_trace() calls in dependencies involving trylocks.
But that caching logic contains a bug. We may not save trace on first
iteration due to early return from check_prev_add(). Then on the
second iteration when we actually need the trace we don't save it
because we think that we've already saved it.
Let check_prev_add() itself control when stack is saved.
There is another bug. Trace variable is protected by graph lock.
But we can temporary release graph lock during printing.
Fix this by invalidating cached stack trace when we release graph lock.
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: glider@google.com
Cc: kcc@google.com
Cc: peter@hurleysoftware.com
Cc: sasha.levin@oracle.com
Link: http://lkml.kernel.org/r/1454593240-121647-1-git-send-email-dvyukov@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A random wakeup can get us out of sigsuspend() without TIF_SIGPENDING
being set.
Avoid that by making sure we were signaled, like sys_pause() does.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Here's a simple fix to correct that issue.
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Merge tag 'trace-v4.5-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
"A cleanup to the stack tracer broke stack tracing on s390. Here's a
simple fix to correct that issue"
* tag 'trace-v4.5-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing/stacktrace: Show entire trace if passed in function not found
For CONFIG_KALLSYMS, we keep two symbol tables and two string tables.
There's one full copy, marked SHF_ALLOC and laid out at the end of the
module's init section. There's also a cut-down version that only
contains core symbols and strings, and lives in the module's core
section.
After module init (and before we free the module memory), we switch
the mod->symtab, mod->num_symtab and mod->strtab to point to the core
versions. We do this under the module_mutex.
However, kallsyms doesn't take the module_mutex: it uses
preempt_disable() and rcu tricks to walk through the modules, because
it's used in the oops path. It's also used in /proc/kallsyms.
There's nothing atomic about the change of these variables, so we can
get the old (larger!) num_symtab and the new symtab pointer; in fact
this is what I saw when trying to reproduce.
By grouping these variables together, we can use a
carefully-dereferenced pointer to ensure we always get one or the
other (the free of the module init section is already done in an RCU
callback, so that's safe). We allocate the init one at the end of the
module init section, and keep the core one inside the struct module
itself (it could also have been allocated at the end of the module
core, but that's probably overkill).
Reported-by: Weilong Chen <chenweilong@huawei.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=111541
Cc: stable@kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
