linux-stable.git/kernel/events/core.c, branch v3.10.8

perf: Fix perf_lock_task_context() vs RCU

2013-07-25T21:07:43+00:00

commit 058ebd0eba3aff16b144eabf4510ed9510e1416e upstream.

Jiri managed to trigger this warning:

 [] ======================================================
 [] [ INFO: possible circular locking dependency detected ]
 [] 3.10.0+ #228 Tainted: G        W
 [] -------------------------------------------------------
 [] p/6613 is trying to acquire lock:
 []  (rcu_node_0){..-...}, at: [] rcu_read_unlock_special+0xa7/0x250
 []
 [] but task is already holding lock:
 []  (&ctx->lock){-.-...}, at: [] perf_lock_task_context+0xd9/0x2c0
 []
 [] which lock already depends on the new lock.
 []
 [] the existing dependency chain (in reverse order) is:
 []
 [] -> #4 (&ctx->lock){-.-...}:
 [] -> #3 (&rq->lock){-.-.-.}:
 [] -> #2 (&p->pi_lock){-.-.-.}:
 [] -> #1 (&rnp->nocb_gp_wq[1]){......}:
 [] -> #0 (rcu_node_0){..-...}:

Paul was quick to explain that due to preemptible RCU we cannot call
rcu_read_unlock() while holding scheduler (or nested) locks when part
of the read side critical section was preemptible.

Therefore solve it by making the entire RCU read side non-preemptible.

Also pull out the retry from under the non-preempt to play nice with RT.

Reported-by: Jiri Olsa 
Helped-out-by: Paul E. McKenney 
Signed-off-by: Peter Zijlstra 
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf: Remove WARN_ON_ONCE() check in __perf_event_enable() for valid scenario

2013-07-25T21:07:42+00:00

commit 06f417968beac6e6b614e17b37d347aa6a6b1d30 upstream.

The '!ctx->is_active' check has a valid scenario, so
there's no need for the warning.

The reason is that there's a time window between the
'ctx->is_active' check in the perf_event_enable() function
and the __perf_event_enable() function having:

  - IRQs on
  - ctx->lock unlocked

where the task could be killed and 'ctx' deactivated by
perf_event_exit_task(), ending up with the warning below.

So remove the WARN_ON_ONCE() check and add comments to
explain it all.

This addresses the following warning reported by Vince Weaver:

[  324.983534] ------------[ cut here ]------------
[  324.984420] WARNING: at kernel/events/core.c:1953 __perf_event_enable+0x187/0x190()
[  324.984420] Modules linked in:
[  324.984420] CPU: 19 PID: 2715 Comm: nmi_bug_snb Not tainted 3.10.0+ #246
[  324.984420] Hardware name: Supermicro X8DTN/X8DTN, BIOS 4.6.3 01/08/2010
[  324.984420]  0000000000000009 ffff88043fce3ec8 ffffffff8160ea0b ffff88043fce3f00
[  324.984420]  ffffffff81080ff0 ffff8802314fdc00 ffff880231a8f800 ffff88043fcf7860
[  324.984420]  0000000000000286 ffff880231a8f800 ffff88043fce3f10 ffffffff8108103a
[  324.984420] Call Trace:
[  324.984420]    [] dump_stack+0x19/0x1b
[  324.984420]  [] warn_slowpath_common+0x70/0xa0
[  324.984420]  [] warn_slowpath_null+0x1a/0x20
[  324.984420]  [] __perf_event_enable+0x187/0x190
[  324.984420]  [] remote_function+0x40/0x50
[  324.984420]  [] generic_smp_call_function_single_interrupt+0xbe/0x130
[  324.984420]  [] smp_call_function_single_interrupt+0x27/0x40
[  324.984420]  [] call_function_single_interrupt+0x6f/0x80
[  324.984420]    [] ? _raw_spin_unlock_irqrestore+0x41/0x70
[  324.984420]  [] perf_event_exit_task+0x14d/0x210
[  324.984420]  [] ? switch_task_namespaces+0x24/0x60
[  324.984420]  [] do_exit+0x2b6/0xa40
[  324.984420]  [] ? _raw_spin_unlock_irq+0x2c/0x30
[  324.984420]  [] do_group_exit+0x49/0xc0
[  324.984420]  [] get_signal_to_deliver+0x254/0x620
[  324.984420]  [] do_signal+0x57/0x5a0
[  324.984420]  [] ? __do_page_fault+0x2a4/0x4e0
[  324.984420]  [] ? retint_restore_args+0xe/0xe
[  324.984420]  [] ? retint_signal+0x11/0x84
[  324.984420]  [] do_notify_resume+0x65/0x80
[  324.984420]  [] retint_signal+0x46/0x84
[  324.984420] ---[ end trace 442ec2f04db3771a ]---

Reported-by: Vince Weaver 
Signed-off-by: Jiri Olsa 
Suggested-by: Peter Zijlstra 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1373384651-6109-2-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf: Clone child context from parent context pmu

2013-07-25T21:07:42+00:00

commit 734df5ab549ca44f40de0f07af1c8803856dfb18 upstream.

Currently when the child context for inherited events is
created, it's based on the pmu object of the first event
of the parent context.

This is wrong for the following scenario:

  - HW context having HW and SW event
  - HW event got removed (closed)
  - SW event stays in HW context as the only event
    and its pmu is used to clone the child context

The issue starts when the cpu context object is touched
based on the pmu context object (__get_cpu_context). In
this case the HW context will work with SW cpu context
ending up with following WARN below.

Fixing this by using parent context pmu object to clone
from child context.

Addresses the following warning reported by Vince Weaver:

[ 2716.472065] ------------[ cut here ]------------
[ 2716.476035] WARNING: at kernel/events/core.c:2122 task_ctx_sched_out+0x3c/0x)
[ 2716.476035] Modules linked in: nfsd auth_rpcgss oid_registry nfs_acl nfs locn
[ 2716.476035] CPU: 0 PID: 3164 Comm: perf_fuzzer Not tainted 3.10.0-rc4 #2
[ 2716.476035] Hardware name: AOpen   DE7000/nMCP7ALPx-DE R1.06 Oct.19.2012, BI2
[ 2716.476035]  0000000000000000 ffffffff8102e215 0000000000000000 ffff88011fc18
[ 2716.476035]  ffff8801175557f0 0000000000000000 ffff880119fda88c ffffffff810ad
[ 2716.476035]  ffff880119fda880 ffffffff810af02a 0000000000000009 ffff880117550
[ 2716.476035] Call Trace:
[ 2716.476035]  [] ? warn_slowpath_common+0x5b/0x70
[ 2716.476035]  [] ? task_ctx_sched_out+0x3c/0x5f
[ 2716.476035]  [] ? perf_event_exit_task+0xbf/0x194
[ 2716.476035]  [] ? do_exit+0x3e7/0x90c
[ 2716.476035]  [] ? __do_fault+0x359/0x394
[ 2716.476035]  [] ? do_group_exit+0x66/0x98
[ 2716.476035]  [] ? get_signal_to_deliver+0x479/0x4ad
[ 2716.476035]  [] ? __perf_event_task_sched_out+0x230/0x2d1
[ 2716.476035]  [] ? do_signal+0x3c/0x432
[ 2716.476035]  [] ? ctx_sched_in+0x43/0x141
[ 2716.476035]  [] ? perf_event_context_sched_in+0x7a/0x90
[ 2716.476035]  [] ? __perf_event_task_sched_in+0x31/0x118
[ 2716.476035]  [] ? mmdrop+0xd/0x1c
[ 2716.476035]  [] ? finish_task_switch+0x7d/0xa6
[ 2716.476035]  [] ? do_notify_resume+0x20/0x5d
[ 2716.476035]  [] ? retint_signal+0x3d/0x78
[ 2716.476035] ---[ end trace 827178d8a5966c3d ]---

Reported-by: Vince Weaver 
Signed-off-by: Jiri Olsa 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1373384651-6109-1-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

perf: Fix mmap() accounting hole

2013-06-19T10:44:13+00:00

Vince's fuzzer once again found holes. This time it spotted a leak in
the locked page accounting.

When an event had redirected output and its close() was the last
reference to the buffer we didn't have a vm context to undo accounting.

Change the code to destroy the buffer on the last munmap() and detach
all redirected events at that time. This provides us the right context
to undo the vm accounting.

Reported-and-tested-by: Vince Weaver 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20130604084421.GI8923@twins.programming.kicks-ass.net
Cc: 
Signed-off-by: Ingo Molnar

perf: Fix perf mmap bugs

2013-05-28T09:05:08+00:00

Vince reported a problem found by his perf specific trinity
fuzzer.

Al noticed 2 problems with perf's mmap():

 - it has issues against fork() since we use vma->vm_mm for accounting.
 - it has an rb refcount leak on double mmap().

We fix the issues against fork() by using VM_DONTCOPY; I don't
think there's code out there that uses this; we didn't hear
about weird accounting problems/crashes. If we do need this to
work, the previously proposed VM_PINNED could make this work.

Aside from the rb reference leak spotted by Al, Vince's example
prog was indeed doing a double mmap() through the use of
perf_event_set_output().

This exposes another problem, since we now have 2 events with
one buffer, the accounting gets screwy because we account per
event. Fix this by making the buffer responsible for its own
accounting.

Reported-by: Vince Weaver 
Signed-off-by: Peter Zijlstra 
Cc: Al Viro 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Link: http://lkml.kernel.org/r/20130528085548.GA12193@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar

perf: Factor out auxiliary events notification

2013-05-07T11:17:29+00:00

Add perf_event_aux() function to send out all types of
auxiliary events - mmap, task, comm events. For each type
there's match and output functions defined and used as
callbacks during perf_event_aux processing.

This way we can centralize the pmu/context iterating and
event matching logic. Also since lot of the code was
duplicated, this patch reduces the .text size about 2kB
on my setup:

  snipped output from 'objdump -x kernel/events/core.o'

  before:
  Idx Name          Size
    0 .text         0000d313

  after:
  Idx Name          Size
    0 .text         0000cad3

Signed-off-by: Jiri Olsa 
Acked-by: Peter Zijlstra 
Cc: Arnaldo Carvalho de Melo 
Cc: Namhyung Kim 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Cc: Borislav Petkov 
Link: http://lkml.kernel.org/r/1367857638-27631-3-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar

perf: Fix EXIT event notification

2013-05-07T11:17:28+00:00

The perf_event_task_ctx() function needs to be called with
preemption disabled, since it's checking for currently
scheduled cpu against event cpu.

We disable preemption for task related perf event context
if there's one defined, leaving up to the chance which cpu
it gets scheduled in.

Signed-off-by: Jiri Olsa 
Acked-by: Peter Zijlstra 
Cc: Arnaldo Carvalho de Melo 
Cc: Namhyung Kim 
Cc: Corey Ashford 
Cc: Frederic Weisbecker 
Cc: Paul Mackerras 
Cc: Stephane Eranian 
Cc: Borislav Petkov 
Link: http://lkml.kernel.org/r/1367857638-27631-2-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar

Merge commit '8700c95adb03' into timers/nohz

2013-05-02T15:54:19+00:00

The full dynticks tree needs the latest RCU and sched
upstream updates in order to fix some dependencies.

Merge a common upstream merge point that has these
updates.

Conflicts:
	include/linux/perf_event.h
	kernel/rcutree.h
	kernel/rcutree_plugin.h

Signed-off-by: Frederic Weisbecker

Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-04-30T14:41:01+00:00

Pull perf updates from Ingo Molnar:
"Features:

- Add "uretprobes" - an optimization to uprobes, like kretprobes are
an optimization to kprobes. "perf probe -x file sym%return" now
works like kretprobes. By Oleg Nesterov.

- Introduce per core aggregation in 'perf stat', from Stephane
Eranian.

- Add memory profiling via PEBS, from Stephane Eranian.

- Event group view for 'annotate' in --stdio, --tui and --gtk, from
Namhyung Kim.

- Add support for AMD NB and L2I "uncore" counters, by Jacob Shin.

- Add Ivy Bridge-EP uncore support, by Zheng Yan

- IBM zEnterprise EC12 oprofile support patchlet from Robert Richter.

- Add perf test entries for checking breakpoint overflow signal
handler issues, from Jiri Olsa.

- Add perf test entry for for checking number of EXIT events, from
Namhyung Kim.

- Add perf test entries for checking --cpu in record and stat, from
Jiri Olsa.

- Introduce perf stat --repeat forever, from Frederik Deweerdt.

- Add --no-demangle to report/top, from Namhyung Kim.

- PowerPC fixes plus a couple of cleanups/optimizations in uprobes
and trace_uprobes, by Oleg Nesterov.

Various fixes and refactorings:

- Fix dependency of the python binding wrt libtraceevent, from
Naohiro Aota.

- Simplify some perf_evlist methods and to allow 'stat' to share code
with 'record' and 'trace', by Arnaldo Carvalho de Melo.

- Remove dead code in related to libtraceevent integration, from
Namhyung Kim.

- Revert "perf sched: Handle PERF_RECORD_EXIT events" to get 'perf
sched lat' back working, by Arnaldo Carvalho de Melo

- We don't use Newt anymore, just plain libslang, by Arnaldo Carvalho
de Melo.

- Kill a bunch of die() calls, from Namhyung Kim.

- Fix build on non-glibc systems due to libio.h absence, from Cody P
Schafer.

- Remove some perf_session and tracing dead code, from David Ahern.

- Honor parallel jobs, fix from Borislav Petkov

- Introduce tools/lib/lk library, initially just removing duplication
among tools/perf and tools/vm. from Borislav Petkov

... and many more I missed to list, see the shortlog and git log for
more details."

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (136 commits)
perf/x86/intel/P4: Robistify P4 PMU types
perf/x86/amd: Fix AMD NB and L2I "uncore" support
perf/x86/amd: Remove old-style NB counter support from perf_event_amd.c
perf/x86: Check all MSRs before passing hw check
perf/x86/amd: Add support for AMD NB and L2I "uncore" counters
perf/x86/intel: Add Ivy Bridge-EP uncore support
perf/x86/intel: Fix SNB-EP CBO and PCU uncore PMU filter management
perf/x86: Avoid kfree() in CPU_{STARTING,DYING}
uprobes/perf: Avoid perf_trace_buf_prepare/submit if ->perf_events is empty
uprobes/tracing: Don't pass addr=ip to perf_trace_buf_submit()
uprobes/tracing: Change create_trace_uprobe() to support uretprobes
uprobes/tracing: Make seq_printf() code uretprobe-friendly
uprobes/tracing: Make register_uprobe_event() paths uretprobe-friendly
uprobes/tracing: Make uprobe_{trace,perf}_print() uretprobe-friendly
uprobes/tracing: Introduce is_ret_probe() and uretprobe_dispatcher()
uprobes/tracing: Introduce uprobe_{trace,perf}_print() helpers
uprobes/tracing: Generalize struct uprobe_trace_entry_head
uprobes/tracing: Kill the pointless local_save_flags/preempt_count calls
uprobes/tracing: Kill the pointless seq_print_ip_sym() call
uprobes/tracing: Kill the pointless task_pt_regs() calls
...

Merge branch 'for-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2013-04-30T02:14:20+00:00

Pull cgroup updates from Tejun Heo:

 - Fixes and a lot of cleanups.  Locking cleanup is finally complete.
   cgroup_mutex is no longer exposed to individual controlelrs which
   used to cause nasty deadlock issues.  Li fixed and cleaned up quite a
   bit including long standing ones like racy cgroup_path().

 - device cgroup now supports proper hierarchy thanks to Aristeu.

 - perf_event cgroup now supports proper hierarchy.

 - A new mount option "__DEVEL__sane_behavior" is added.  As indicated
   by the name, this option is to be used for development only at this
   point and generates a warning message when used.  Unfortunately,
   cgroup interface currently has too many brekages and inconsistencies
   to implement a consistent and unified hierarchy on top.  The new flag
   is used to collect the behavior changes which are necessary to
   implement consistent unified hierarchy.  It's likely that this flag
   won't be used verbatim when it becomes ready but will be enabled
   implicitly along with unified hierarchy.

   The option currently disables some of broken behaviors in cgroup core
   and also .use_hierarchy switch in memcg (will be routed through -mm),
   which can be used to make very unusual hierarchy where nesting is
   partially honored.  It will also be used to implement hierarchy
   support for blk-throttle which would be impossible otherwise without
   introducing a full separate set of control knobs.

   This is essentially versioning of interface which isn't very nice but
   at this point I can't see any other options which would allow keeping
   the interface the same while moving towards hierarchy behavior which
   is at least somewhat sane.  The planned unified hierarchy is likely
   to require some level of adaptation from userland anyway, so I think
   it'd be best to take the chance and update the interface such that
   it's supportable in the long term.

   Maintaining the existing interface does complicate cgroup core but
   shouldn't put too much strain on individual controllers and I think
   it'd be manageable for the foreseeable future.  Maybe we'll be able
   to drop it in a decade.

Fix up conflicts (including a semantic one adding a new #include to ppc
that was uncovered by header the file changes) as per Tejun.

* 'for-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (45 commits)
  cpuset: fix compile warning when CONFIG_SMP=n
  cpuset: fix cpu hotplug vs rebuild_sched_domains() race
  cpuset: use rebuild_sched_domains() in cpuset_hotplug_workfn()
  cgroup: restore the call to eventfd->poll()
  cgroup: fix use-after-free when umounting cgroupfs
  cgroup: fix broken file xattrs
  devcg: remove parent_cgroup.
  memcg: force use_hierarchy if sane_behavior
  cgroup: remove cgrp->top_cgroup
  cgroup: introduce sane_behavior mount option
  move cgroupfs_root to include/linux/cgroup.h
  cgroup: convert cgroupfs_root flag bits to masks and add CGRP_ prefix
  cgroup: make cgroup_path() not print double slashes
  Revert "cgroup: remove bind() method from cgroup_subsys."
  perf: make perf_event cgroup hierarchical
  cgroup: implement cgroup_is_descendant()
  cgroup: make sure parent won't be destroyed before its children
  cgroup: remove bind() method from cgroup_subsys.
  devcg: remove broken_hierarchy tag
  cgroup: remove cgroup_lock_is_held()
  ...