Messages in this thread | | | Date | Fri, 12 May 2017 12:42:52 +0100 | From | Chris Wilson <> | Subject | Re: [PATCH] perf/core: Avoid removing shared pmu_context on unregister |
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On Fri, May 12, 2017 at 11:40:32AM +0100, Chris Wilson wrote: > 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@chris-wilson.co.uk> > Cc: David Carrillo-Cisneros <davidcc@google.com> > Cc: Peter Zijlstra (Intel) <peterz@infradead.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: <stable@vger.kernel.org> # 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))
Bleh, that find should be under some guard, such as the mutex we held ealier.
> + free_pmu_context(pmu); > } > EXPORT_SYMBOL_GPL(perf_pmu_unregister); > > -- > 2.11.0 >
-- Chris Wilson, Intel Open Source Technology Centre
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