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From: Tejun Heo <tj@kernel.org>
To: Andrea Righi <arighi@nvidia.com>
Cc: David Vernet <void@manifault.com>,
	Changwoo Min <changwoo@igalia.com>,
	Emil Tsalapatis <emil@etsalapatis.com>,
	sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] sched/core: Avoid requeueing a singleton balance callback
Date: Tue, 20 Oct 2026 07:57:26 -1000	[thread overview]
Message-ID: <aterhhiPAi-Bib7Z@slm.duckdns.org> (raw)
In-Reply-To: <20261020084400.845842-2-arighi@nvidia.com>

On Tue, Oct 20, 2026 at 10:43:19AM +0200, Andrea Righi wrote:
> With proxy execution, __schedule() can call set_next_task_scx() with
> SNT_REPICK and then SNT_PICK for the same donor. Both calls queue the
> kick_sync balance callback while kick_sync_pending remains set.
> 
> When the callback is the only list entry, its next pointer is NULL, so
> the existing duplicate check misses it. Queueing it again links it to
> itself and causes the wait to run twice.
> 
> Also check whether the callback is already the head of the list to
> reject the second insertion.
> 
> Fixes: e2859566ffbc ("sched_ext: Queue the kick_sync wait from set_next_task_scx()")
> Reported-by: Tejun Heo <tj@kernel.org>
> Link: https://lore.kernel.org/r/08cac02c604dd73ef96fc92eb29d692b@kernel.org
> Signed-off-by: Andrea Righi <arighi@nvidia.com>

Can you resend this to Peter? Please feel free to add

 Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun

  reply	other threads:[~2026-10-20 17:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-20  8:43 [PATCHSET sched_ext/for-7.4-fixes] sched_ext: Fix proxy execution balance callbacks Andrea Righi
2026-10-20  8:43 ` [PATCH 1/3] sched/core: Avoid requeueing a singleton balance callback Andrea Righi
2026-10-20 17:57   ` Tejun Heo [this message]
2026-10-20 18:20   ` Tejun Heo
2026-10-20  8:43 ` [PATCH 2/3] sched_ext: Use irq_work for deferred actions with proxy execution Andrea Righi
2026-10-20 18:20   ` Tejun Heo
2026-10-20  8:43 ` [PATCH 3/3] sched_ext: Remove the foreign CPU check from the kick_sync wait Andrea Righi
2026-10-20 18:20   ` Tejun Heo

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