linux-kernel - Re: perf: WARNING: kernel/events/core.c:4893 perf_mmap

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Date:   Wed, 24 Aug 2016 14:44:12 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Will Deacon <will.deacon@....com>
Cc:     Vince Weaver <vincent.weaver@...ne.edu>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: perf: WARNING: kernel/events/core.c:4893 perf_mmap_close

Will Deacon <will.deacon@....com> writes:

> A little bit of digging suggests that the preempt count isn't balanced
> across the call to perf_pmu_output_stop from perf_mmap_close. Further
> digging revealed the unbalanced get_cpu_ptr in __perf_pmu_output_stop.
> Fix below!

Oh gee, that's embarrassing. Thanks!

> This patch uses this_cpu_ptr instead of get_cpu_ptr, since preemption is
> already disabled by the caller.
>
> Fixes: 95ff4ca26c49 ("perf/core: Free AUX pages in unmap path")
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Will Deacon <will.deacon@....com>

Reviewed-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>

Regards,
--
Alex