From 69771f65837bbfc26d206ec43b9295d61b4ea8f3 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 12 May 2017 12:45:25 +0100 Subject: [PATCH] perf/core: Avoid removing shared pmu_context on unregister In commit 1fd7e4169954 ("perf/core: Remove perf_cpu_context::unique_pmu"), the search for another user of the pmu_cpu_context was removed, and so we unconditionally free it during perf_pmu_unregister. This leads to random corruption later and a BUG at mm/percpu.c:689. v2: Check for shared pmu_contexts under the mutex. Fixes: 1fd7e4169954 ("perf/core: Remove perf_cpu_context::unique_pmu") Signed-off-by: Chris Wilson Cc: David Carrillo-Cisneros Cc: Peter Zijlstra (Intel) Cc: Ingo Molnar Cc: # v4.11+ Link: http://patchwork.freedesktop.org/patch/msgid/20170512114525.17575-1-chris@chris-wilson.co.uk --- kernel/events/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index bc9b98a9af9ac1..c8f65daee1f95d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10733,7 +10733,8 @@ void perf_pmu_unregister(struct pmu *pmu) device_del(pmu->dev); put_device(pmu->dev); } - free_pmu_context(pmu); + if (!find_pmu_context(pmu->task_ctx_nr)) + free_pmu_context(pmu); mutex_unlock(&pmus_lock); } EXPORT_SYMBOL_GPL(perf_pmu_unregister);