From nobody Fri Apr 3 10:17:52 2026 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 6D26D3BC691 for ; Tue, 24 Mar 2026 19:13:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774379630; cv=none; b=lOVA97O6D2pVwiDu4ayn8bE5dSnYjK6CS3QS3WKaY5BUDl+2AVhtzXznDY8J7kEQIc9/BJnRIZc9KefWoev4ZcV6a+fIyMo2SPY8xL6bz0kA0OJeiEEZ7W8hoctUmptp8Q6H/YWyeKFuyShVGHQnn9wEdIY/pmwRB4QmJPEF8Nw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774379630; c=relaxed/simple; bh=msTCyA1PkdHuWuPlFQDkzCVw5Fo1Q6YWL1Ro+s/waj0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=aAfmpbnkITbSSFFOQb8vesx0XOK+dvTXOB4D9ubYikwmENEne37TQdbCJt6ij98uVTlw2XcMIKB04jIdWll1Qa9pasr9wqdd5ZbKlsUy/eD5SaeSlm+XDuM9EOOpWtB6E5DwqCqavnJL65FW9KSx28aUqUnfRZZxY4pi1u8UNY0= 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=Ol8P+b57; arc=none smtp.client-ip=209.85.216.74 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="Ol8P+b57" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-35ba237d2e0so5230261a91.2 for ; Tue, 24 Mar 2026 12:13:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1774379629; x=1774984429; 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=Dl6sTkn6PQBY5ESOoos6QwsTSfV85Htk250jFpA56CI=; b=Ol8P+b57P+ehp+t6bLwT23fNVKNKHwedNeiAiSM0UDEXXX51HRh4MsNE/WVTCCaZFq 2nKXUkpvlsBLetgFb7jsho7eZhrtXjyM0QIhNBRScYxxp8wWkQhnlNg3dsXo4+XAT3K/ 0z/uvHmIBAJzpKEiaDPQ5+77P6oXk+aKCCpLHFhlijqsEy3uc860rdpKSBNMdrw1f4yc Y4V/zvuNP5TZRaIeUc0qsFiC3lU0dbZL2tDooM72hYM7HjjUXPHE5n+OfkEqkl9BGmVV 9uL2e+etqzK6APAj7Aj/wnl3rDzs6RlgW9sL2FJD3W0Vlh7s5kV03c7/WfgCxuoOL4DE z3gA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774379629; x=1774984429; 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=Dl6sTkn6PQBY5ESOoos6QwsTSfV85Htk250jFpA56CI=; b=cMiRwCwhe5KVTCK5n+8XhZvoOip4daYQqo3FEaV4KyXePpTaAvxhKQa5E7xiq+8gmp 9t+7BPFEfNkQ1iE1zaWP1RRqfJbMPfnMstShTb5yZS75CybTs30RHL1c98HHUQnOyr7J uTYCPCkutfI48D8bG1HB68cJh6b9qG7EPnHAcNo+7bS27uIT2s8nb8lokOebi7oLcXxh OIjFqYmVxNgaVdndjMgnaC5sj3oEwruwePVKsXI5Ps41ztCRttWN1IALE88hsqwLImOT r3PfHQMMunh7Tyigba7IFC45z0K5LIWNPbAUqCxTmdk7bARl2qaugaTvl9xZuY7go1pF X9YA== X-Gm-Message-State: AOJu0YxAtXvKbaLmHQoPkWdVLF3ZsnUgIfvo286GFyyEMHNyuMvtL+97 ZCMlpL0Ylk6N9fj3Wibypx3iK91cFsh+xS83oL3MarfO0hx1j4C4GWzWwW4Rovm9mUAFRZatAa4 Tyt7FY27QBFEQZyD20OVtwNy1piy3+dG8mmCXJvEbx8r9DCTVUajA9ClxQjMXnozOI9iA6G6WgT pbz4iij1s1fEPdGYA8zMeETvRjV22Kz+zURxph4NUlgMtYRKvv X-Received: from pjbgv15.prod.google.com ([2002:a17:90b:11cf:b0:35b:cc2b:ddfa]) (user=jstultz job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1dc6:b0:359:f7d2:a1f9 with SMTP id 98e67ed59e1d1-35c0dc811c0mr438630a91.2.1774379628422; Tue, 24 Mar 2026 12:13:48 -0700 (PDT) Date: Tue, 24 Mar 2026 19:13:20 +0000 In-Reply-To: <20260324191337.1841376-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260324191337.1841376-1-jstultz@google.com> X-Mailer: git-send-email 2.53.0.1018.g2bb0e51243-goog Message-ID: <20260324191337.1841376-6-jstultz@google.com> Subject: [PATCH v26 05/10] sched: Fix modifying donor->blocked on without proper locking From: John Stultz To: LKML Cc: John Stultz , K Prateek Nayak , Joel Fernandes , Qais Yousef , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Valentin Schneider , Steven Rostedt , Ben Segall , Zimuzo Ezeozue , Mel Gorman , Will Deacon , Waiman Long , Boqun Feng , "Paul E. McKenney" , Metin Kaya , Xuewen Yan , Thomas Gleixner , Daniel Lezcano , Suleiman Souhlal , kuyo chang , hupu , kernel-team@android.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Introduce an action enum in find_proxy_task() which allows us to handle work needed to be done outside the mutex.wait_lock and task.blocked_lock guard scopes. This ensures proper locking when we clear the donor's blocked_on pointer in proxy_deactivate(), and the switch statement will be useful as we add more cases to handle later in this series. Reviewed-by: K Prateek Nayak Signed-off-by: John Stultz --- v23: * Split out from earlier patch. v24: * Minor re-ordering local variables to keep with style as 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: Mel Gorman 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 | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7187c63174cd2..c43e7926fda51 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6571,7 +6571,7 @@ static struct task_struct *proxy_deactivate(struct rq= *rq, struct task_struct *d * as unblocked, as we aren't doing proxy-migrations * yet (more logic will be needed then). */ - donor->blocked_on =3D NULL; + clear_task_blocked_on(donor, NULL); } return NULL; } @@ -6595,6 +6595,7 @@ static struct task_struct *proxy_deactivate(struct rq= *rq, struct task_struct *d static struct task_struct * find_proxy_task(struct rq *rq, struct task_struct *donor, struct rq_flags = *rf) { + enum { FOUND, DEACTIVATE_DONOR } action =3D FOUND; struct task_struct *owner =3D NULL; int this_cpu =3D cpu_of(rq); struct task_struct *p; @@ -6628,12 +6629,14 @@ find_proxy_task(struct rq *rq, struct task_struct *= donor, struct rq_flags *rf) =20 if (!READ_ONCE(owner->on_rq) || owner->se.sched_delayed) { /* XXX Don't handle blocked owners/delayed dequeue yet */ - return proxy_deactivate(rq, donor); + action =3D DEACTIVATE_DONOR; + break; } =20 if (task_cpu(owner) !=3D this_cpu) { /* XXX Don't handle migrations yet */ - return proxy_deactivate(rq, donor); + action =3D DEACTIVATE_DONOR; + break; } =20 if (task_on_rq_migrating(owner)) { @@ -6691,6 +6694,13 @@ find_proxy_task(struct rq *rq, struct task_struct *d= onor, struct rq_flags *rf) */ } =20 + /* Handle actions we need to do outside of the guard() scope */ + switch (action) { + case DEACTIVATE_DONOR: + return proxy_deactivate(rq, donor); + case FOUND: + /* fallthrough */; + } WARN_ON_ONCE(owner && !owner->on_rq); return owner; } --=20 2.53.0.1018.g2bb0e51243-goog