From nobody Tue Feb 10 02:59:07 2026 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 EFF752627FC; Mon, 6 Oct 2025 10:46:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759747562; cv=none; b=WoGM0x3Q38NqXE9fT5sMdL/FIfnvhQtQGJMKCzKuduip3HOHdD2iLI65zsKA295dCDHU6UEv94/CwnbcpNuCp8uRSPaFDbuLDjJT6AECENYqpux0xGktiIeymfg5JhCjv5FWa2UmIeaGed+VWodvMys15Zcx2H5PJIktha9wr3M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759747562; c=relaxed/simple; bh=c9xoIob1d4Dr2GfYVz5Rit2g6x6od88j4KsW99vCxOI=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=f6mY3yqT5uOJtJq7B+Jd40zjo/69JZeewK8z4LGZzlPnEGXSexvoP4y5bolLA7w+JtdPm7w96mlBKtx8r1Id81/8DXV0YbNqVdcPis25I12wvSQaWAsz/W92cT1S+4u0+x2IsG1d+BSPncO7ic/94+taxgzJYrVLvv8T+wKNrGk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=D6EvLUAm; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="D6EvLUAm" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=BgD2e8jwOUPdYSAJVBJ3I9+RfPG0RYrESbEwPiGDcBM=; b=D6EvLUAmY4DbKVsAczPiazAJ9v psS8akrf1uI3rZrGQwRls/RtJebAjfO8UJJaJWSdrXxX2Kv6+HRbwcICxHyx5IBaMyNuCEjMH8W6h UlFqvQSKQFHRNXVlWsT6fKP2agBhBqtGPP6R3V/9dqYlwAl79QPUOq3znO2fl8G+1vRDCEcLu+snV WCDuDz0mXWIDqMbozNhtyYjea1irX/nFtJhIscs5DppyqgQj59jUh+n/ipiQJxjyl8CTf5FHahWDU LkcoTZJ0ovj/Jdc6zhl004j8c4FQI4gYOfcSLdvl+SxbWyrKqge4iJGrprrV8Rln/YOsJcT7dmMea YrqGPGgQ==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1v5iix-00000009yaz-0RHa; Mon, 06 Oct 2025 10:45:48 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id CC577300754; Mon, 06 Oct 2025 12:45:47 +0200 (CEST) Message-ID: <20251006104526.964100769@infradead.org> User-Agent: quilt/0.68 Date: Mon, 06 Oct 2025 12:44:06 +0200 From: Peter Zijlstra To: tj@kernel.org Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, longman@redhat.com, hannes@cmpxchg.org, mkoutny@suse.com, void@manifault.com, arighi@nvidia.com, changwoo@igalia.com, cgroups@vger.kernel.org, sched-ext@lists.linux.dev, liuwenfang@honor.com, tglx@linutronix.de Subject: [PATCH 04/12] sched: Cleanup sched_delayed handling for class switches References: <20251006104402.946760805@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Use the new sched_class::switching_from() method to dequeue delayed tasks before switching to another class. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Reviewed-by: Vincent Guittot --- kernel/sched/core.c | 12 ++++++++---- kernel/sched/ext.c | 6 ------ kernel/sched/fair.c | 7 +++++++ kernel/sched/syscalls.c | 3 --- 4 files changed, 15 insertions(+), 13 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7368,9 +7368,6 @@ void rt_mutex_setprio(struct task_struct queue_flag &=3D ~(DEQUEUE_SAVE | DEQUEUE_MOVE); } =20 - if (prev_class !=3D next_class && p->se.sched_delayed) - dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK); - scoped_guard (sched_change, p, queue_flag) { /* * Boosting condition are: @@ -10845,8 +10842,15 @@ struct sched_change_ctx *sched_change_be if (WARN_ON_ONCE(flags & (DEQUEUE_SAVE | DEQUEUE_MOVE))) flags &=3D ~(DEQUEUE_SAVE | DEQUEUE_MOVE); =20 - if (p->sched_class->switching_from) + if (p->sched_class->switching_from) { + /* + * switching_from_fair() assumes CLASS implies NOCLOCK; + * fixing this assumption would mean switching_from() + * would need to be able to change flags. + */ + WARN_ON(!(flags & DEQUEUE_NOCLOCK)); p->sched_class->switching_from(rq, p); + } } =20 *ctx =3D (struct sched_change_ctx){ --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -3924,9 +3924,6 @@ static void scx_disable_workfn(struct kt queue_flags &=3D ~(DEQUEUE_SAVE | DEQUEUE_MOVE); } =20 - if (old_class !=3D new_class && p->se.sched_delayed) - dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_N= OCLOCK); - scoped_guard (sched_change, p, queue_flags) { p->sched_class =3D new_class; } @@ -4677,9 +4674,6 @@ static int scx_enable(struct sched_ext_o queue_flags &=3D ~(DEQUEUE_SAVE | DEQUEUE_MOVE); } =20 - if (old_class !=3D new_class && p->se.sched_delayed) - dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_N= OCLOCK); - scoped_guard (sched_change, p, queue_flags) { p->scx.slice =3D SCX_SLICE_DFL; p->sched_class =3D new_class; --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -13237,6 +13237,12 @@ static void attach_task_cfs_rq(struct ta attach_entity_cfs_rq(se); } =20 +static void switching_from_fair(struct rq *rq, struct task_struct *p) +{ + if (p->se.sched_delayed) + dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK); +} + static void switched_from_fair(struct rq *rq, struct task_struct *p) { detach_task_cfs_rq(p); @@ -13638,6 +13644,7 @@ DEFINE_SCHED_CLASS(fair) =3D { =20 .reweight_task =3D reweight_task_fair, .prio_changed =3D prio_changed_fair, + .switching_from =3D switching_from_fair, .switched_from =3D switched_from_fair, .switched_to =3D switched_to_fair, =20 --- a/kernel/sched/syscalls.c +++ b/kernel/sched/syscalls.c @@ -689,9 +689,6 @@ int __sched_setscheduler(struct task_str queue_flags &=3D ~(DEQUEUE_SAVE | DEQUEUE_MOVE); } =20 - if (prev_class !=3D next_class && p->se.sched_delayed) - dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK); - scoped_guard (sched_change, p, queue_flags) { =20 if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) {