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
..
amd	Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-10-23 16:16:40 +01:00
intel	perf/x86/intel: Delay memory deallocation until x86_pmu_dead_cpu()	2019-02-04 08:44:51 +01:00
core.c	perf/x86/intel: Move branch tracing setup to the Intel-specific source file	2018-11-22 09:45:09 +01:00
Kconfig	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
Makefile	perf/x86/events: Add an AMD-specific Makefile	2017-01-30 12:01:19 +01:00
msr.c	x86/cpu: Sanitize FAM6_ATOM naming	2018-10-02 10:14:32 +02:00
perf_event.h	perf/x86/intel: Add generic branch tracing check to intel_pmu_has_bts()	2018-11-22 09:45:09 +01:00