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linux-next/arch/x86/events/intel
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Peter Zijlstra 602cae04c4 perf/x86/intel: Delay memory deallocation until x86_pmu_dead_cpu() 
intel_pmu_cpu_prepare() allocated memory for ->shared_regs among other
members of struct cpu_hw_events. This memory is released in
intel_pmu_cpu_dying() which is wrong. The counterpart of the
intel_pmu_cpu_prepare() callback is x86_pmu_dead_cpu().

Otherwise if the CPU fails on the UP path between CPUHP_PERF_X86_PREPARE
and CPUHP_AP_PERF_X86_STARTING then it won't release the memory but
allocate new memory on the next attempt to online the CPU (leaking the
old memory).
Also, if the CPU down path fails between CPUHP_AP_PERF_X86_STARTING and
CPUHP_PERF_X86_PREPARE then the CPU will go back online but never
allocate the memory that was released in x86_pmu_dying_cpu().

Make the memory allocation/free symmetrical in regard to the CPU hotplug
notifier by moving the deallocation to intel_pmu_cpu_dead().

This started in commit:

   a7e3ed1e47 ("perf: Add support for supplementary event registers").

In principle the bug was introduced in v2.6.39 (!), but it will almost
certainly not backport cleanly across the big CPU hotplug rewrite between v4.7-v4.15...

[ bigeasy: Added patch description. ]
[ mingo: Added backporting guidance. ]

Reported-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> # With developer hat on
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> # With maintainer hat on
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: acme@kernel.org
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: jolsa@kernel.org
Cc: kan.liang@linux.intel.com
Cc: namhyung@kernel.org
Cc: <stable@vger.kernel.org>
Fixes: a7e3ed1e47 ("perf: Add support for supplementary event registers").
Link: https://lkml.kernel.org/r/20181219165350.6s3jvyxbibpvlhtq@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:44:51 +01:00
..
bts.c x86: Fix various typos in comments 2018-12-03 10:49:13 +01:00
core.c perf/x86/intel: Delay memory deallocation until x86_pmu_dead_cpu() 2019-02-04 08:44:51 +01:00
cstate.c x86/cpu: Sanitize FAM6_ATOM naming 2018-10-02 10:14:32 +02:00
ds.c x86: Fix various typos in comments 2018-12-03 10:49:13 +01:00
knc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
lbr.c perf/x86/intel: Add support/quirk for the MISPREDICT bit on Knights Landing CPUs 2018-09-10 10:03:01 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
p4.c x86: Fix various typos in comments 2018-12-03 10:49:13 +01:00
p6.c x86/cpu: Rename cpu_data.x86_mask to cpu_data.x86_stepping 2018-02-15 01:15:52 +01:00
pt.c perf/x86/intel/pt: add new capability for Intel PT 2018-12-21 11:28:33 +01:00
pt.h perf/x86/intel/pt: Export pt_cap_get() 2018-12-21 11:28:32 +01:00
rapl.c x86/cpu: Sanitize FAM6_ATOM naming 2018-10-02 10:14:32 +02:00
uncore_nhmex.c perf/x86/intel/uncore: Correct fixed counter index check for NHM 2018-05-31 12:36:28 +02:00
uncore_snb.c perf/x86/intel/uncore: Support CoffeeLake 8th CBOX 2018-11-12 05:03:26 +01:00
uncore_snbep.c perf/x86/intel/uncore: Add Node ID mask 2019-02-04 08:44:43 +01:00
uncore.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
uncore.h perf/x86/intel/uncore: Support CoffeeLake 8th CBOX 2018-11-12 05:03:26 +01:00