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Message-ID: <20130708164002.GB22923@dyad.programming.kicks-ass.net>
Date: Mon, 8 Jul 2013 18:40:02 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Jiri Olsa <jolsa@...hat.com>
Cc: Vince Weaver <vincent.weaver@...ne.edu>,
linux-kernel@...r.kernel.org, Paul Mackerras <paulus@...ba.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
trinity@...r.kernel.org
Subject: Re: [bisected] perf: yet another fuzzer triggered crash
On Mon, Jul 08, 2013 at 03:50:48PM +0200, Jiri Olsa wrote:
> patch below gets rid of the warning, and probably the
> crash as well
>
> the reason seems to be when HW context is cloned based
> on SW event that happened to get there because of the
> HW leader, which got closed just before (fd[15] event
> in the reproducer)
>
> and the consequence is that in HW context we access
> SW's cpuctx -> and thus overwriting its task_ctx variable
> any time there's *sched_in routine
>
> need to check if that does not break anything else ;-)
>
> jirka
>
> ---
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 1833bc5..1d1f030 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -7465,7 +7465,7 @@ inherit_task_group(struct perf_event *event, struct task_struct *parent,
> * child.
> */
>
> - child_ctx = alloc_perf_context(event->pmu, child);
> + child_ctx = alloc_perf_context(parent_ctx->pmu, child);
> if (!child_ctx)
> return -ENOMEM;
>
Ha! very good catch. Thanks!
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