From nobody Tue Apr 7 14:19:04 2026 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (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 B06EC342519 for ; Fri, 13 Mar 2026 02:30:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773369039; cv=none; b=DVHH3XJvY7Rmevs0xeJnC2XjcCWcbSTdbcVDIdvGbt3A5CN8vtTvBMgPACoWIy7GUxkm7teDiqZXV2Oed66m2A+oKjnplKDEed2w60HhPeVhrQH4Qi0APSemjsG+2Bm4vvfWjNgpRU7otiF6FPK4Nu6K4vQbFbVFanGyCroy12c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773369039; c=relaxed/simple; bh=AKjoayGHIA60ynGU5hWRiNvsYRQB0TZbXDcMYbyU3QQ=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=aoYpNJspy4+wR9nMiVvSkZWadudCuhO8o479w95n80eMm2LuVu5JNCGgF5uHs0DdvIHRCSrMat+6xhoiJtAHHhEj2mhCwg+MX9OgUlbpFrsNDMyXXdPWanINHUopHkVn8W9INd2aLTHAIOGndQjb4DKxgblul1p8SFpNrg5Z8rY= 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=X+kKgaD9; arc=none smtp.client-ip=209.85.214.202 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="X+kKgaD9" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2ae4e9577ceso120364095ad.1 for ; Thu, 12 Mar 2026 19:30:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1773369033; x=1773973833; 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=v6kyjTaRuEIVy2OJjeoHdnZzJalhFMinIdG0tUIi2C0=; b=X+kKgaD9h48UvBFrp9G8q2ou8q3zSm6jcv45rN5harBdF2GoXBJBAlOyiCVgVLOUEN Vgpn0zM5T+sXEOsOXPbT71KNBILV3etUlsZJkhKnKcP6oEHB21ibJT7Bb0V9izQ6Ty24 H81POQuxLLqPtNF/hReEb3Q6jPCisg6OsjlzcjVcxkcOYXTrHuasLFY8l1aeCzka0Uqj DdgWsZTRQKdyO5M3CMi6Gba72I7tyUbA+/wAHS5/v712kRTT4PqaPt42VlKdDRisg94C 0HC7hP/+86IIyJN2u7CsV/Qd/ZR9FNvLrs4EnsV/sW4d6njiNipJd9PYjMUMVKON695A VvFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773369033; x=1773973833; 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=v6kyjTaRuEIVy2OJjeoHdnZzJalhFMinIdG0tUIi2C0=; b=hckoRp2yFBAIbbO1570CXOdnWaT6dcuqEQmdU9CGWeJDkBMeGvvKupJTdtqb5UKXoz YGF5sCygtoxmsz7pD63zkxtn0V4HijVBBrtMLzQudV5+MpnHOny96e2UVjv5mjUHDe1Q 80AxQXGwTwhnExM12tfzHySmT8F30Kz+k8t0dhsBaZYSXxRDwlQAuTcL3MmktNH1NqKr 22XL1JU55flG8RBYvmp5VlIYIrqNXxc/b2ia3ea8HHXlIKbns5JqK+jj7ildOcZuEvUg wMlLifttfSfFq0vWf1gm2tDWy1BgOLCJbFNw4dfClKi6TrfHMhfKncgl6IK4VsSHtz+E T4vw== X-Gm-Message-State: AOJu0Yy1cQnhW06FC8HKM23dXoKgjWVBUrBlzGlr0gMKzXd75xpBL0yS zDy8DWDM71hjwhjo0KuiX3Udft+M0dM1dpyy6Ly0duglzc4hcqB3GvYChPX8FQ4Q85myasI3Ssh HnXZ2MX8U3xnndIec933mPfnAlN/XQGn2Fco6kbw3VW+gLy7aX8wmX/K9PqTL0YZCbW7nqVsP7D vtfCWe45fMbIrPjFR3IbNqYBuZ+nFs9bS3eSDHjjcOWea7K+5M X-Received: from plqq12.prod.google.com ([2002:a17:902:c74c:b0:2ae:5a45:5844]) (user=jstultz job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:d2cd:b0:2ae:8081:c5a0 with SMTP id d9443c01a7336-2aecab0c799mr15328895ad.39.1773369032508; Thu, 12 Mar 2026 19:30:32 -0700 (PDT) Date: Fri, 13 Mar 2026 02:30:05 +0000 In-Reply-To: <20260313023022.2902479-1-jstultz@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260313023022.2902479-1-jstultz@google.com> X-Mailer: git-send-email 2.53.0.880.g73c4285caa-goog Message-ID: <20260313023022.2902479-5-jstultz@google.com> Subject: [PATCH v25 4/9] 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 96e2784dbba49..0bb7272106c9e 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6568,7 +6568,7 @@ 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; } @@ -6592,6 +6592,7 @@ 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; @@ -6625,12 +6626,14 @@ 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)) { @@ -6688,6 +6691,13 @@ 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 2.53.0.880.g73c4285caa-goog