From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f69.google.com (mail-pj1-f69.google.com [209.85.216.69]) (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 B438C3ABD82 for ; Fri, 7 Aug 2026 03:52:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786074763; cv=none; b=D1hfZXK65EsUOHYjVbz7XmjrAQbUrezozuVAiuFLknW7VPB6YX9eTN+bCJQpps07MClXy5ccbEnigaGK9wxO7fPq1S+q28pJZOuLDO9JEQTU1I9NzJCr19iEMcfRzdxVHwjuNC0Xg5+/L+jrqMvDOKq7xmLLyU+FcKIAMFpASRo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786074763; c=relaxed/simple; bh=CSOVsS8UWQGlIziI7NKPdi5vrcIQ+oL85iiVMBgLlvA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=qgwatiHZU947zpwfz+dfv7RG0l0cWnQYS5b0i4SXT1bd9fp9+HBxMLhLmTvjmR/RLcwMJhdOP/vFCZX9pBFtVQL43dX4Ks/hIJnp18sOOSZv5X+CavUerXJYWPV8tt12z+SkxQsiWlIcevL3qjVFtfQBtOyZv3HLt2TzbsshFys= 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=MI+BtNTb; arc=none smtp.client-ip=209.85.216.69 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="MI+BtNTb" Received: by mail-pj1-f69.google.com with SMTP id 98e67ed59e1d1-38e54b6556aso3260130a91.2 for ; Thu, 06 Aug 2026 20:52:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1786074761; x=1786679561; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=v3lhC9D0tWuMtdDZrYkdJhxklzGgK946m8G3sbfQfYM=; b=MI+BtNTbxAA1pGe3jabswWRt5x1sziNCvTrhlWYPuqVg0NGC86t14Bva7x3fVrlJnN v+Sqkoh9lvh/lVUwJ4WIw/NTiwLU4in4tf3+ffAXehI4H1p/4+qeV2TgmivFpYZ3zn9c KS81Ond8cu4RKE4hAoocG9JtKOxMwxVhA2VDuRIgAAhzAB3W3FRy2/3SiFkANdZTzcZl 5FFLdDyVx14+8bdjHdfnObIenKgUriWNQwKMdW0bYJRxDw9qDNmPQKaDTyn2gog5ANfQ dfD8GOg24YrImddvdS/z6URP9IQcdGDlzygJMItOdKXbxqLxSfOAA9ivbJ/ZJScPZbby Pz+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786074761; x=1786679561; h=content-type: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:content-type; bh=v3lhC9D0tWuMtdDZrYkdJhxklzGgK946m8G3sbfQfYM=; b=KqcHIJVEbdp8kg6x5BTNbotc60oGEW63/Kr5kJxYFW0FYBzRiuFoNBMvVa33fjXp+3 EF4DYFE1aZwTpI1Cbo68oqtBYPiEltrxOpK23W62XScmedLuCecwNHk2aOByHfbIBiRc K5kGSGt1eckkDK2pQc0JeWPfmWLu44JO1bVohILq+XEHziEGfsChuf5M6KCe7gMRCgRH aTrXg9Zpw1IMZS+AYXSmLLcdhLiBKYOrTi6YaHe8x0C+kx58FqJDSd7/lQWAoruFrwi1 FRSxpPLZucifWql7kJEKJb+Lbl+QxoxPWO7OZXAU08YhDNG2F8ZN33OkwysAdkuJtmNf mrRw== X-Gm-Message-State: AOJu0YyYup7OE0rWQ6RU2rXB4UEvNWj1ahurtfFXbpQCPzRmmiDfhDjl 4Z2g+tPYNBtuWtXI2WIB5s3FJY4iptXKSd4PohPlfL+xl2l9p6DlsheygVx8uPX5LwVGi422xJW +z75JY7wlvOI+Qc2X98WQcpmT1NVgXEMKBkKnOoO7wxhO+viYcNnx7jjK7MTUxHk/4ppRzezwbO kZanXGoYSHDQt7CTnVWInhOKVWxe+rLAtKi7gi/cfSv95SJs6u X-Received: from pjbnd7.prod.google.com ([2002:a17:90b:4cc7:b0:38e:b8e0:d97d]) (user=jstultz job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:4e8d:b0:381:cef1:11ac with SMTP id 98e67ed59e1d1-3903c58ed40mr20127680a91.10.1786074760894; Thu, 06 Aug 2026 20:52:40 -0700 (PDT) Date: Fri, 7 Aug 2026 03:52:13 +0000 In-Reply-To: <20260807035232.1881495-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260807035232.1881495-1-jstultz@google.com> X-Mailer: git-send-email 2.55.0.654.g21b8a5bc05-goog Message-ID: <20260807035232.1881495-8-jstultz@google.com> Subject: [RESEND][PATCH v31 7/9] 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 , Andrea Righi , 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: Andrea Righi 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 564762ed36f2d..1bf60d78c9208 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6819,9 +6819,9 @@ 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 @@ -6834,13 +6834,20 @@ 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); } -- 2.55.0.654.g21b8a5bc05-goog