From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 395753630A4; Wed, 13 May 2026 04:59:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778648400; cv=none; b=tYFjq1BPVJTG4OY96EgfT1D27MJ04oJKCvewAX7oDGAphAbudO2bMiMEHJMON+bFE+4Ror7dPBYfCke0ZMz0EnE5EJIKXdMStiSL7mvKvMJDlMwAQ3uiwHlT1wBtxMubG+RHDf3ESxL7KdH4V0o+nVsi20QOeUCaSMiaXTzprKQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778648400; c=relaxed/simple; bh=OcJJur5kBVC2vJOyBNxR6/x/CsmZAaJam6oljgn6EmI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RMJBw2jV6UKkq5w5A/tdFwu7zjuMhwqjfBk72aVOVRHu7ysUJSmFNepUmsZH1USKM1+k50xYwOOtxFvMMzOXzm+2Buy0JG0A/vHwKXhp7lfOPDD2Hju5K7cQmUs9MsAVptJNThUoSWsNPLiu8DvIub7y5Z9kEJTUFh31lbo8Fow= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X04Su6Sg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="X04Su6Sg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90CBDC2BCB7; Wed, 13 May 2026 04:59:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778648399; bh=OcJJur5kBVC2vJOyBNxR6/x/CsmZAaJam6oljgn6EmI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=X04Su6Sgc1dbaeIKVYmHwgNYmIZEqHsSPsCyhWnXDOgVmZSEmCJFofKHfkXrQxA7U ib34zXgWBvDhi2nVrK+YXGIBQ4b+iQ4scMqCA9W4R95iX16ZJMEIAEmoGtksqnmPFu RFIsk+qnYvWAoT73D95GQ8MCwvUOnxVqPhR1ppAnEvoTwYNfVOyGZiPGdapwbxsVF5 ZU8qxn3FYsQNbYDatXV1aaylNPefLZ4JaSBGapHQGKjvaZsh8BkNCecWGPhkbiTdQG LNjlXJQK+XILyuxydSe8GdyxjJARiBr98l2uQxplpFTHhI3RxvMTomjwPeXDoV/S+Y SICHl7EKxOPEQ== Message-ID: <2f509cbf-f14f-4dfc-8ba9-d53dc10e0aad@kernel.org> Date: Wed, 13 May 2026 06:59:56 +0200 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 7.0 247/307] sched_ext: Skip tasks with stale task_rq in bypass_lb_cpu() To: Greg Kroah-Hartman , stable@vger.kernel.org Cc: patches@lists.linux.dev, Chris Mason , Tejun Heo , Andrea Righi References: <20260512173940.117428952@linuxfoundation.org> <20260512173945.338221208@linuxfoundation.org> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 12. 05. 26, 19:40, Greg Kroah-Hartman wrote: > 7.0-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Tejun Heo > > commit da2d81b4118a74e65d2335e221a38d665902a98c upstream. > > bypass_lb_cpu() transfers tasks between per-CPU bypass DSQs without > migrating them - task_cpu() only updates when the donee later consumes the > task via move_remote_task_to_local_dsq(). If the LB timer fires again before > consumption and the new DSQ becomes a donor, @p is still on the previous CPU > and task_rq(@p) != donor_rq. @p can't be moved without its own rq locked. > > Skip such tasks. > > Fixes: 95d1df610cdc ("sched_ext: Implement load balancer for bypass mode") > Cc: stable@vger.kernel.org # v6.19+ > Reported-by: Chris Mason > Signed-off-by: Tejun Heo > Reviewed-by: Andrea Righi > Signed-off-by: Greg Kroah-Hartman > --- > kernel/sched/ext.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > --- a/kernel/sched/ext.c > +++ b/kernel/sched/ext.c > @@ -4008,6 +4008,15 @@ resume: > if (cpumask_empty(donee_mask)) > break; > > + /* > + * If an earlier pass placed @p on @donor_dsq from a different > + * CPU and the donee hasn't consumed it yet, @p is still on the > + * previous CPU and task_rq(@p) != @donor_rq. @p can't be moved > + * without its rq locked. Skip. > + */ > + if (task_rq(p) != donor_rq) > + continue; As others pointed out already: [ 75s] In file included from ../kernel/sched/build_policy.c:62: [ 75s] ../kernel/sched/ext.c: In function ‘bypass_lb_cpu’: [ 75s] ../kernel/sched/ext.c:4019:35: error: ‘donor_rq’ undeclared (first use in this function); did you mean ‘donee_rq’? [ 75s] 4019 | if (task_rq(p) != donor_rq) [ 75s] | ^~~~~~~~ [ 75s] | donee_rq Donor and donor_rq were introduced in: commit ff06f727a9412b3c9f2f13f1441a5a0d2a31366b Author: Tejun Heo Date: Fri Mar 6 07:58:03 2026 -1000 sched_ext: Move bypass_dsq into scx_sched_pcpu thanks, -- js suse labs