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authorPeter Zijlstra <peterz@infradead.org>2018-12-19 17:53:50 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-02-12 19:46:14 +0100
commitdb85eb4162da282b1c25b1d62ed01a434bfdd6d0 (patch)
tree79bdbc5b9e9af2dfb34e9fc4e4c595c7d37b8d2e
parente36c4e23b970ca4c53812b4e9bf733ca17280f65 (diff)
perf/x86/intel: Delay memory deallocation until x86_pmu_dead_cpu()
commit 602cae04c4864bb3487dfe4c2126c8d9e7e1614a upstream. 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: a7e3ed1e47011 ("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: a7e3ed1e47011 ("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> [ He Zhe: Fixes conflict caused by missing disable_counter_freeze which is introduced since v4.20 af3bdb991a5cb. ] Signed-off-by: He Zhe <zhe.he@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/events/intel/core.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 7bb80151bfff..1cb5ff3ee728 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3420,6 +3420,11 @@ static void free_excl_cntrs(int cpu)
static void intel_pmu_cpu_dying(int cpu)
{
+ fini_debug_store_on_cpu(cpu);
+}
+
+static void intel_pmu_cpu_dead(int cpu)
+{
struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
struct intel_shared_regs *pc;
@@ -3431,8 +3436,6 @@ static void intel_pmu_cpu_dying(int cpu)
}
free_excl_cntrs(cpu);
-
- fini_debug_store_on_cpu(cpu);
}
static void intel_pmu_sched_task(struct perf_event_context *ctx,
@@ -3521,6 +3524,7 @@ static __initconst const struct x86_pmu core_pmu = {
.cpu_prepare = intel_pmu_cpu_prepare,
.cpu_starting = intel_pmu_cpu_starting,
.cpu_dying = intel_pmu_cpu_dying,
+ .cpu_dead = intel_pmu_cpu_dead,
};
static struct attribute *intel_pmu_attrs[];
@@ -3560,6 +3564,8 @@ static __initconst const struct x86_pmu intel_pmu = {
.cpu_prepare = intel_pmu_cpu_prepare,
.cpu_starting = intel_pmu_cpu_starting,
.cpu_dying = intel_pmu_cpu_dying,
+ .cpu_dead = intel_pmu_cpu_dead,
+
.guest_get_msrs = intel_guest_get_msrs,
.sched_task = intel_pmu_sched_task,
};