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From: Marco Elver <elver@google.com>
To: peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com,
	namhyung@kernel.org, acme@kernel.org,
	alexander.shishkin@linux.intel.com, jolsa@redhat.com
Cc: syzbot <syzbot+23843634c323e144fd0b@syzkaller.appspotmail.com>,
	andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
	daniel@iogearbox.net, john.fastabend@gmail.com, kafai@fb.com,
	kpsingh@kernel.org, linux-kernel@vger.kernel.org,
	linux-perf-users@vger.kernel.org, netdev@vger.kernel.org,
	songliubraving@fb.com, syzkaller-bugs@googlegroups.com,
	yhs@fb.com
Subject: Re: [PATCH] perf: Ignore sigtrap for tracepoints destined for other tasks
Date: Wed, 17 Nov 2021 15:07:07 +0100	[thread overview]
Message-ID: <CANpmjNNR32aoFK4B6wErLvgbo3mADH5MLRt797brzA0Vtifm1g@mail.gmail.com> (raw)
In-Reply-To: <YYpoCOBmC/kJWfmI@elver.google.com>

On Tue, 9 Nov 2021 at 13:22, Marco Elver <elver@google.com> wrote:
> syzbot reported that the warning in perf_sigtrap() fires, saying that
> the event's task does not match current:
>
>  | WARNING: CPU: 0 PID: 9090 at kernel/events/core.c:6446 perf_pending_event+0x40d/0x4b0 kernel/events/core.c:6513
[...]
> This happened because the 'sched_wakeup' tracepoint also takes a task
> argument passed on to perf_tp_event(), which is used to deliver the
> event to that other task.
>
> Since we cannot deliver synchronous signals to other tasks, skip an event if
> perf_tp_event() is targeted at another task and perf_event_attr::sigtrap is
> set, which will avoid ever entering perf_sigtrap() for such events.
[...]

Hmm, I made the mistake of sending this in the merge-window.
Any comments?

Thanks,
-- Marco

      reply	other threads:[~2021-11-17 14:07 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-09 12:17 [syzbot] WARNING in perf_pending_event syzbot
2021-11-09 12:22 ` [PATCH] perf: Ignore sigtrap for tracepoints destined for other tasks Marco Elver
2021-11-17 14:07   ` Marco Elver [this message]

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