From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 18D643A2574 for ; Wed, 22 Apr 2026 23:07:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776899252; cv=none; b=mxqldPqlpCk7qfuKqbfqmgv6ZNdzJgqU9ZS/wNl8Zlo/EjsYxt5GpWfqipmLnL9zFkHqPVq1F+58SaH6wyhec9dxsovZB4R0zUXD62HFQ5Y2gNOBN1IwVezOigp0q2LDXggNVmpX//l9pOLzM6VtUBpJ4ZWPJR3F+DteErZtjV8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776899252; c=relaxed/simple; bh=bjd20hXdQONHNffvBFuajylxmzBngkvfkrYIICVO01A=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=CNrmIuK0JfF/cdOdz6O3Oz7JlXbrvsfKVybqPl+UO0Y1aBx7EVxxBSvv37LhvzScNbsFh4dyWjPJQQaQ4xOI4RQIxnwxCGb4PKqdcUTp4PQKkFnu20a3q5plWf1m2vIPPiTXQse7+9fNGzBdNxpwr9mFhnnzdQGK+PkrGzVo51I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jstultz.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=HmazZIwE; arc=none smtp.client-ip=209.85.214.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jstultz.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="HmazZIwE" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2b465bf993cso62216985ad.1 for ; Wed, 22 Apr 2026 16:07:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1776899239; x=1777504039; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=O15jZGurrpTf939HxX2cOKx38Q52K7VnoCedb3nSxhE=; b=HmazZIwEBIZPR5ZwpSGwldAHSKyJQOvudCII6iTjlU5nDCmlDCKqZ+vIudpN4EXVSv Ofdy9RuvxZRmBWKICbgbWlyT4AQArs6tAzqenKcxP1x3ziGBYAUwBIOwJmgCwL5QBnW3 Sr0sHCGu1uYo/FsWiIrhn9EfaRRmTl276Gife2L6xfbo2gyu/qGve0opRTdQQPogr06y FxrV0CRWCTAskH8W/U68ICDqltanMBOUgillKn/d8+ExdSXHq/k+ZWumn6SNquE+q3sP EX4u24A7f+D3CBFGRA7lu0L8StLt9QEYRW6aFxIV1yYX0ZSV8J6cMWIUX3tfleAR+a41 3y0A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776899239; x=1777504039; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=O15jZGurrpTf939HxX2cOKx38Q52K7VnoCedb3nSxhE=; b=YiSfR8to1vOERhKPNdcgOqJfGWZLc09AQQMEpP9fHx5q/2dtC4Wue1nkD1Rg+e6ock pvsq/QdrLtiZNwmsvjAM/ISS5z0iEVAsyVh2qxhM/DQyHYOw9TK7FgFYSmzUtq60jjzg 6gjQWfqFx39rxE2j6ONGxoTvndG0TCtijFNIXy1la1UJzwbZ6FMFkTmdnFkppGTtQV9J mbjOqxmyap4sr+oIfHPUzYaDRedW/1qMHiLTDYr8NuGiiJVDKeOew7yiI6bDY1CeG6Ay /lmO2Nt/+f/25uVpmEw0vl50wuyzt2015zjrRL/OcULdLn5IRwCwKlzqHW5HUskP1yik K2dw== X-Gm-Message-State: AOJu0YwM+Utj3soCcWc9K0F0JKWpXNFaQR53eV1l+mdgZcZkD2qP1AGR +HHGKzX7ZwFTYcSqtQeRyn2bdkbmNn0AQC0TNCB04iZZjQogaHQXfGcimuoH4Djdub+tvusDsMz yoRVj4o26uy7n1zbnj+y/LJycNtwSBSy7X7jGPCqZBLSN7KzJ2L503jbxSoqdNrQOBz4DmznxTz mEhcOA1RS41cVRiHMAL67v9l/OqFgeEYGWNPABNdBWO4Qy2hLo X-Received: from plbkg11.prod.google.com ([2002:a17:903:60b:b0:2b4:5fd0:a45d]) (user=jstultz job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:7009:b0:2b2:45b7:307f with SMTP id d9443c01a7336-2b5f9eb0988mr189984615ad.9.1776899239198; Wed, 22 Apr 2026 16:07:19 -0700 (PDT) Date: Wed, 22 Apr 2026 23:06:49 +0000 In-Reply-To: <20260422230659.903191-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260422230659.903191-1-jstultz@google.com> X-Mailer: git-send-email 2.54.0.rc2.533.g4f5dca5207-goog Message-ID: <20260422230659.903191-9-jstultz@google.com> Subject: [PATCH v28 8/8] sched: Migrate whole chain in proxy_migrate_task() From: John Stultz To: LKML Cc: John Stultz , Joel Fernandes , Qais Yousef , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Valentin Schneider , Steven Rostedt , Ben Segall , Zimuzo Ezeozue , Will Deacon , Waiman Long , Boqun Feng , "Paul E. McKenney" , Metin Kaya , Xuewen Yan , K Prateek Nayak , Thomas Gleixner , Daniel Lezcano , Suleiman Souhlal , kuyo chang , hupu , kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Instead of migrating one task each time through find_proxy_task(), we can walk up the blocked_donor ptrs and migrate the entire current chain in one go. This was broken out of earlier patches and held back while the series was being stabilized, but I wanted to re-introduce it. Signed-off-by: John Stultz --- v12: * Earlier this was re-using blocked_node, but I hit a race with activating blocked entities, and to avoid it introduced a new migration_node listhead v18: * Add init_task initialization of migration_node as suggested by Suleiman v22: * Move migration_node under CONFIG_SCHED_PROXY_EXEC as suggested by K Prateek v25: * Use se.group_node instead of adding migration_node, as suggsested by K Prateek * Integrated attach_tasks() cleanups suggested by K Prateek Cc: Joel Fernandes Cc: Qais Yousef Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Valentin Schneider Cc: Steven Rostedt Cc: Ben Segall Cc: Zimuzo Ezeozue Cc: Will Deacon Cc: Waiman Long Cc: Boqun Feng Cc: "Paul E. McKenney" Cc: Metin Kaya Cc: Xuewen Yan Cc: K Prateek Nayak Cc: Thomas Gleixner Cc: Daniel Lezcano Cc: Suleiman Souhlal Cc: kuyo chang Cc: hupu Cc: kernel-team@android.com --- kernel/sched/core.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index edd418dde1e47..886984a02adad 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6779,9 +6779,9 @@ static void proxy_migrate_task(struct rq *rq, struct rq_flags *rf, __must_hold(__rq_lockp(rq)) { struct rq *target_rq = cpu_rq(target_cpu); + LIST_HEAD(migrate_list); lockdep_assert_rq_held(rq); - WARN_ON(p == rq->curr); /* * Since we are migrating a blocked donor, it could be rq->donor, * and we want to make sure there aren't any references from this @@ -6794,13 +6794,20 @@ static void proxy_migrate_task(struct rq *rq, struct rq_flags *rf, * before we release the lock. */ proxy_resched_idle(rq); - - deactivate_task(rq, p, DEQUEUE_NOCLOCK); - proxy_set_task_cpu(p, target_cpu); - + for (; p; p = p->blocked_donor) { + WARN_ON(p == rq->curr); + deactivate_task(rq, p, DEQUEUE_NOCLOCK); + proxy_set_task_cpu(p, target_cpu); + /* + * We can re-use se.group_node to migrate the thing, + * because @p is deactivated (won't be balanced) and + * we hold the rq_lock. + */ + list_add(&p->se.group_node, &migrate_list); + } proxy_release_rq_lock(rq, rf); - attach_one_task(target_rq, p); + __attach_tasks(target_rq, &migrate_list); proxy_reacquire_rq_lock(rq, rf); } -- 2.54.0.rc2.533.g4f5dca5207-goog