From: sashiko-bot@kernel.org
To: "Tengda Wu" <wutengda@huaweicloud.com>
Cc: linux-perf-users@vger.kernel.org
Subject: Re: [PATCH v3 1/2] perf/core: Prevent duplicate sigtrap task work enqueue
Date: Thu, 05 Nov 2026 09:40:40 +0000 [thread overview]
Message-ID: <sashiko-outbox-198770@kernel.org> (raw)
In-Reply-To: <ff842e802e9ecb74510a90964f8ad2c4825834b7.1793870900.git.wutengda@huaweicloud.com>
> The sigtrap handling in __perf_event_overflow() checks
> event->pending_work before calling task_work_add(), but only sets
> pending_work after the task work has been queued.
>
> This leaves a window where an NMI can interrupt task_work_add()
> and re-enter __perf_event_overflow() for the same event. Since
> pending_work is still zero, the nested invocation can enqueue
> the same pending_task again.
>
> The re-entrant call path is:
>
> __perf_event_overflow()
> task_work_add()
> kasan_record_aux_stack()
> <NMI>
> [ ... ]
> Also use READ_ONCE() when checking pending_work in the
> exclude_kernel warning path to avoid an unsynchronized read.
>
> Fixes: c5d93d23a260 ("perf: Enqueue SIGTRAP always via task_work.")
> Signed-off-by: Tengda Wu <wutengda@huaweicloud.com>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1793870900.git.wutengda@huaweicloud.com?part=1
next prev parent reply other threads:[~2026-11-05 9:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-05 9:30 [PATCH v3 0/2] perf/core: Fix sigtrap task_work races Tengda Wu
2026-11-05 9:30 ` [PATCH v3 1/2] perf/core: Prevent duplicate sigtrap task work enqueue Tengda Wu
2026-11-05 9:40 ` sashiko-bot [this message]
2026-11-05 9:30 ` [PATCH v3 2/2] perf/core: Disable context fast-swap for sigtrap events Tengda Wu
2026-11-05 9:48 ` sashiko-bot
2026-11-05 11:10 ` Tengda Wu
2026-11-05 9:43 ` [PATCH v3 0/2] perf/core: Fix sigtrap task_work races Tengda Wu
2026-11-05 9:47 ` Tengda Wu
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