linux-kernel - Re: [PATCH] perf: Fix race between close() and fork()

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Message-ID: <87h88dvotq.fsf@ashishki-desk.ger.corp.intel.com>
Date:   Tue, 25 Jun 2019 15:20:33 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>
Cc:     Arnaldo Carvalho de Melo <acme@...hat.com>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        jolsa@...hat.com, dvyukov@...gle.com, namhyung@...nel.org,
        xiexiuqi@...wei.com,
        syzbot+a24c397a29ad22d86c98@...kaller.appspotmail.com,
        alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH] perf: Fix race between close() and fork()

Peter Zijlstra <peterz@...radead.org> writes:

> Solve it by using the fact that detached events still have a reference
> count on their (previous) context. With this perf_event_free_task()
> can detect when events have escaped and wait for their destruction.
>
> Cc: Mark Rutland <mark.rutland@....com>
> Fixes: 82d94856fa22 ("perf/core: Fix lock inversion between perf,trace,cpuhp")
> Reported-by: syzbot+a24c397a29ad22d86c98@...kaller.appspotmail.com
> Debugged-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

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

Regards,
--
Alex