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Andrey Vagin 20afc60f89 x86, perf: Check that current->mm is alive before getting user callchain 
An event may occur when an mm is already released.

I added an event in dequeue_entity() and caught a panic with
the following backtrace:

[  434.421110] BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
[  434.421258] IP: [<ffffffff810464ac>] __get_user_pages_fast+0x9c/0x120
...
[  434.421258] Call Trace:
[  434.421258]  [<ffffffff8101ae81>] copy_from_user_nmi+0x51/0xf0
[  434.421258]  [<ffffffff8109a0d5>] ? sched_clock_local+0x25/0x90
[  434.421258]  [<ffffffff8101b048>] perf_callchain_user+0x128/0x170
[  434.421258]  [<ffffffff811154cd>] ? __perf_event_header__init_id+0xed/0x100
[  434.421258]  [<ffffffff81116690>] perf_prepare_sample+0x200/0x280
[  434.421258]  [<ffffffff81118da8>] __perf_event_overflow+0x1b8/0x290
[  434.421258]  [<ffffffff81065240>] ? tg_shares_up+0x0/0x670
[  434.421258]  [<ffffffff8104fe1a>] ? walk_tg_tree+0x6a/0xb0
[  434.421258]  [<ffffffff81118f44>] perf_swevent_overflow+0xc4/0xf0
[  434.421258]  [<ffffffff81119150>] do_perf_sw_event+0x1e0/0x250
[  434.421258]  [<ffffffff81119204>] perf_tp_event+0x44/0x70
[  434.421258]  [<ffffffff8105701f>] ftrace_profile_sched_block+0xdf/0x110
[  434.421258]  [<ffffffff8106121d>] dequeue_entity+0x2ad/0x2d0
[  434.421258]  [<ffffffff810614ec>] dequeue_task_fair+0x1c/0x60
[  434.421258]  [<ffffffff8105818a>] dequeue_task+0x9a/0xb0
[  434.421258]  [<ffffffff810581e2>] deactivate_task+0x42/0xe0
[  434.421258]  [<ffffffff814bc019>] thread_return+0x191/0x808
[  434.421258]  [<ffffffff81098a44>] ? switch_task_namespaces+0x24/0x60
[  434.421258]  [<ffffffff8106f4c4>] do_exit+0x464/0x910
[  434.421258]  [<ffffffff8106f9c8>] do_group_exit+0x58/0xd0
[  434.421258]  [<ffffffff8106fa57>] sys_exit_group+0x17/0x20
[  434.421258]  [<ffffffff8100b202>] system_call_fastpath+0x16/0x1b

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1314693156-24131-1-git-send-email-avagin@openvz.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
 		2011-08-31 15:56:31 +02:00
..
mcheck x86, mce: Use mce_sysdev_ prefix to group functions 2011-06-16 12:10:16 +02:00
mtrr mtrr: fix UP breakage caused during switch to stop_machine 2011-08-25 11:02:29 -07:00
.gitignore
…
Makefile [CPUFREQ] Move x86 drivers to drivers/cpufreq/ 2011-05-19 18:51:07 -04:00
amd.c x86, amd: Do not enable ARAT feature on AMD processors below family 0x12 2011-05-26 10:38:30 -07:00
bugs.c x86-32, fpu: Fix DNA exception during check_fpu() 2011-06-30 17:29:47 -07:00
bugs_64.c
…
centaur.c x86, cpu: mv display_cacheinfo -> cpu_detect_cache_sizes 2009-11-23 11:59:53 -08:00
common.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
cpu.h Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-10-21 13:18:36 -07:00
cyrix.c x86, cpu: mv display_cacheinfo -> cpu_detect_cache_sizes 2009-11-23 11:59:53 -08:00
hypervisor.c x86, hyper: Change hypervisor detection order 2011-07-08 16:22:29 -07:00
intel.c x86, intel, power: Correct the MSR_IA32_ENERGY_PERF_BIAS message 2011-07-15 15:13:55 -07:00
intel_cacheinfo.c x86, AMD, cacheinfo: Fix L3 cache index disable checks 2011-05-16 11:24:27 -07:00
mkcapflags.pl
…
mshyperv.c x86: Export the symbol ms_hyperv 2010-07-08 14:12:03 -07:00
perf_event.c x86, perf: Check that current->mm is alive before getting user callchain 2011-08-31 15:56:31 +02:00
perf_event_amd.c perf, arch: Add generic NODE cache events 2011-07-01 11:06:38 +02:00
perf_event_intel.c perf, x86: Add model 45 SandyBridge support 2011-08-09 11:58:06 +02:00
perf_event_intel_ds.c perf: Remove the perf_output_begin(.sample) argument 2011-07-01 11:06:35 +02:00
perf_event_intel_lbr.c perf, x86: Clean up debugctlmsr bit definitions 2010-03-26 09:41:03 +01:00
perf_event_p4.c x86, perf: P4 PMU - Fix typos in comments and style cleanup 2011-07-21 20:41:54 +02:00
perf_event_p6.c perf, x86: Store perfctr msr addresses in config_base/event_base 2011-02-16 13:30:52 +01:00
perfctr-watchdog.c perf, x86: Add new AMD family 15h msrs to perfctr reservation code 2011-02-16 13:30:50 +01:00
powerflags.c
…
proc.c Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-09-14 07:57:32 -07:00
scattered.c Merge branch 'x86-amd-nb-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-10-21 13:01:08 -07:00
sched.c sched: x86: Name old_perf in a unique way 2009-09-16 11:21:07 +02:00
topology.c x86, cpu: Split addon_cpuid_features.c 2010-07-19 19:02:41 -07:00
transmeta.c x86, cpu: mv display_cacheinfo -> cpu_detect_cache_sizes 2009-11-23 11:59:53 -08:00
umc.c
…
vmware.c x86: Fix common misspellings 2011-03-18 10:39:30 +01:00