From nobody Thu Sep 24 14:25:13 2026 Received: from mta0.migadu.com (out-149.mta0.migadu.com [91.218.175.149]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 853F8440A0A for ; Wed, 23 Sep 2026 21:34:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.149 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790199295; cv=none; b=G9t8pnCfHfbT2rziSMtlqGEvrJGm5ssSqnSHT8yeZfkbcoDUaBMF3XNk+bvgADlhFcv9yN1XhCQ3sr+DWgkM7ZWgurrX5MsIAixwVcVz2a/dmhFoSF4jp44P438WKPAZtX5PbMD5Fo0pjTR997Z1S5b2KqZqnaI3H/rgVawP+XQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790199295; c=relaxed/simple; bh=rb7CP4UYtgy+IXS6D08jHYPv/a6qcfU7VomdBfispcs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=iI2E0SwL0bQ6dOHV38ZZ86dyVdiuKcmBx/v/VVY4QLHQXuIAIpuOU3Te4e/x9TVuXoUWd8jWHadvSZc/G0kMdNgluwHTira/PaB/bUyMjl2Z6s/g8kekSXn0N++765bbzpYmuzQfdA1SJnTbxTuDl79PWDFjhIvj8a8YPPbLoNU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=HnL2tipy; arc=none smtp.client-ip=91.218.175.149 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="HnL2tipy" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=rb7CP4UYtgy+IXS6D08jHYPv/a6qcfU7VomdBfispcs=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790199291; v=1; x=1790804091; b=HnL2tipyUvMaJvc9BPXNfOHSVSlrZuK6eVs5YSLMdcNDJuoy/K9zZE1KskFjPIsAyleFlTik 6dTHonyzloOLQa1xESvu9Ox2t0i9tKvNVTzEjn9EJXocIn9JYDnhGerPN5KUR0eVs/sPDxn33Q1 FznAACwMWKTZDz2PD2E0S7eU= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta11.migadu.com with ESMTPS id 8768a77adbd16e00; Wed, 23 Sep 2026 21:34:51 +0000 X-Mizu-Trace-ID: 8768a77adbd16e00 X-Migadu-Flow: FLOW_OUT From: Usama Arif To: arighi@nvidia.com, bpf@vger.kernel.org, bsegall@google.com, changwoo@igalia.com, dietmar.eggemann@arm.com, etsal@meta.com, juri.lelli@redhat.com, kprateek.nayak@amd.com, linux-kernel@vger.kernel.org, mgorman@suse.de, mingo@redhat.com, peterz@infradead.org, rostedt@goodmis.org, sched-ext@lists.linux.dev, tj@kernel.org, vincent.guittot@linaro.org, void@manifault.com, vschneid@redhat.com, yphbchou0911@gmail.com Cc: Usama Arif Subject: [PATCH] sched_ext: Avoid relocking DSQ during remote DSQ moves Date: Wed, 23 Sep 2026 14:34:44 -0700 Message-ID: <20260923213444.3231509-1-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 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" When scx_bpf_dsq_move*() moves a task from a non-local DSQ to a remote local DSQ, move_task_between_dsqs() drops src_dsq->lock while leaving p->scx.dsq set. The following deactivate_task() then reacquires src_dsq->lock in scx_dispatch_dequeue() to unlink the task and clear p->scx.dsq. Both the source rq and src_dsq are already locked before the source DSQ lock is dropped. Call dispatch_dequeue_locked() there so that deactivate_task() takes the !dsq path and avoids the redundant lock acquisition. Suggested-by: Tejun Heo Signed-off-by: Usama Arif --- kernel/sched/ext/ext.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index f95d1cf8d3d1c..56bc06a56bb34 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -2710,6 +2710,7 @@ static struct rq *move_task_between_dsqs(struct scx_s= ched *sch, raw_spin_unlock(&src_dsq->lock); scx_move_local_task_to_local_dsq(sch, p, enq_flags, dst_rq); } else { + dispatch_dequeue_locked(p, src_dsq); raw_spin_unlock(&src_dsq->lock); move_remote_task_to_local_dsq(sch, p, enq_flags, src_rq, dst_rq); } --=20 2.53.0-Meta