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.
Fixes: 1fd7e4169954 ("perf/core: Remove perf_cpu_context::unique_pmu")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: David Carrillo-Cisneros <davidcc@xxxxxxxxxx>
Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.11+
---
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 aaefaa27e1a6..e62b6207925c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9005,7 +9005,8 @@ 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);
}
EXPORT_SYMBOL_GPL(perf_pmu_unregister);
--
2.11.0