From nobody Thu Dec 18 19:06:18 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A7C7F143873; Mon, 29 Jul 2024 10:34:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722249247; cv=none; b=YsgOWZvvXSG27akh2DQnnKGoLXaFF+x6Ih+uBl3NaSnTf/WSwVxZmWVyTMlYF/F7y8b8Zb1OL3yAAOfXUqDxVgBTTLDR1ogML8PquMRrkv1PKLTL5zbtLWSr5V+3MM7KaujEuoDDkR/Fbgy9qwO1JzMnefe7XK8DN5S7UoQFz5I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722249247; c=relaxed/simple; bh=zIHWDrJs2RXpLhehu4rA00hG9qgjdcou5i4v6wUA7MM=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=FJey5q60/Halx6UMgQ4UqwXgiN0nQukc9sBf6yqctaphxfFpV/v7biHZ4UWE/vH/WOdhAwiTg111ZEadqyl2WvtU7t6oonVEEmP5+Bm/YNGX30Q00dr6aP/R30xODqAHdLV1m3KVxJb5nC//CI3nz7WQIpJZO37naYdxKYevaD0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=q4Gm7IMU; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=W+6w18kl; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="q4Gm7IMU"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="W+6w18kl" Date: Mon, 29 Jul 2024 10:34:02 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1722249243; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EvKTJcJ65cCSvd8gt7vqwEYIEh39ixGD5M1XXmMlgy4=; b=q4Gm7IMUn0SUYnl0LodmOLgzaVGGXLwdEqmngcDDEmBpwjOnJ3gTJaIOSI2nmSbMxSxWvW OqqTh/xnG4YVpdYaLP1bLO8271Pv0oktS8dYriS7wsUDtn1vXEG8x65scorzDeGVKcwjis gIMFIr2gbLImNa9kH9NTGcZWPJJU/W4oCCtLFqG9nY0Rz7fPYrdPToW2XSopRFoAxpIVW7 iTTR/CaU6ZAplByR66ZLO4WOAm7C4LZ1OSgSCIg1LdT1iJVZtXnK+h9ysy63vHOQW2htKU T8tx7u9PuXf1A3f5e71+ncGQ0CIvQzUkmbxfpozEVJrxYyRUYrrsmBN4ZjsN0A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1722249243; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EvKTJcJ65cCSvd8gt7vqwEYIEh39ixGD5M1XXmMlgy4=; b=W+6w18klSNkoAqX9qAW6AQ71TyrDC+z5XaeL3x//HHTqZ3avxLWEPkPUy0OUkKZ5sCxF1o A2gXFZZyJmftRFCg== From: "tip-bot2 for Joel Fernandes (Google)" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched/core: Fix picking of tasks for core scheduling with DL server Cc: Suleiman Souhlal , "Joel Fernandes (Google)" , Daniel Bristot de Oliveira , "Peter Zijlstra (Intel)" , Vineeth Pillai , Juri Lelli , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <172224924259.2215.9246085118455972956.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the sched/core branch of tip: Commit-ID: c8a85394cfdb4696b4e2f8a0f3066a1c921af426 Gitweb: https://git.kernel.org/tip/c8a85394cfdb4696b4e2f8a0f3066a1c9= 21af426 Author: Joel Fernandes (Google) AuthorDate: Mon, 27 May 2024 14:06:54 +02:00 Committer: Peter Zijlstra CommitterDate: Mon, 29 Jul 2024 12:22:37 +02:00 sched/core: Fix picking of tasks for core scheduling with DL server * Use simple CFS pick_task for DL pick_task DL server's pick_task calls CFS's pick_next_task_fair(), this is wrong because core scheduling's pick_task only calls CFS's pick_task() for evaluation / checking of the CFS task (comparing across CPUs), not for actually affirmatively picking the next task. This causes RB tree corruption issues in CFS that were found by syzbot. * Make pick_task_fair clear DL server A DL task pick might set ->dl_server, but it is possible the task will never run (say the other HT has a stop task). If the CFS task is picked in the future directly (say without DL server), ->dl_server will be set. So clear it in pick_task_fair(). This fixes the KASAN issue reported by syzbot in set_next_entity(). (DL refactoring suggestions by Vineeth Pillai). Reported-by: Suleiman Souhlal Signed-off-by: "Joel Fernandes (Google)" Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vineeth Pillai Tested-by: Juri Lelli Link: https://lore.kernel.org/r/b10489ab1f03d23e08e6097acea47442e7d6466f.17= 16811044.git.bristot@kernel.org --- include/linux/sched.h | 3 ++- kernel/sched/deadline.c | 27 ++++++++++++++++++++++----- kernel/sched/fair.c | 23 +++++++++++++++++++++-- kernel/sched/sched.h | 3 ++- 4 files changed, 47 insertions(+), 9 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 4edd7e2..2c1b4ee 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -686,7 +686,8 @@ struct sched_dl_entity { */ struct rq *rq; dl_server_has_tasks_f server_has_tasks; - dl_server_pick_f server_pick; + dl_server_pick_f server_pick_next; + dl_server_pick_f server_pick_task; =20 #ifdef CONFIG_RT_MUTEXES /* diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 747c0c5..8571bc9 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1664,11 +1664,13 @@ void dl_server_stop(struct sched_dl_entity *dl_se) =20 void dl_server_init(struct sched_dl_entity *dl_se, struct rq *rq, dl_server_has_tasks_f has_tasks, - dl_server_pick_f pick) + dl_server_pick_f pick_next, + dl_server_pick_f pick_task) { dl_se->rq =3D rq; dl_se->server_has_tasks =3D has_tasks; - dl_se->server_pick =3D pick; + dl_se->server_pick_next =3D pick_next; + dl_se->server_pick_task =3D pick_task; } =20 void __dl_server_attach_root(struct sched_dl_entity *dl_se, struct rq *rq) @@ -2399,7 +2401,12 @@ static struct sched_dl_entity *pick_next_dl_entity(s= truct dl_rq *dl_rq) return __node_2_dle(left); } =20 -static struct task_struct *pick_task_dl(struct rq *rq) +/* + * __pick_next_task_dl - Helper to pick the next -deadline task to run. + * @rq: The runqueue to pick the next task from. + * @peek: If true, just peek at the next task. Only relevant for dlserver. + */ +static struct task_struct *__pick_next_task_dl(struct rq *rq, bool peek) { struct sched_dl_entity *dl_se; struct dl_rq *dl_rq =3D &rq->dl; @@ -2413,7 +2420,10 @@ again: WARN_ON_ONCE(!dl_se); =20 if (dl_server(dl_se)) { - p =3D dl_se->server_pick(dl_se); + if (IS_ENABLED(CONFIG_SMP) && peek) + p =3D dl_se->server_pick_task(dl_se); + else + p =3D dl_se->server_pick_next(dl_se); if (!p) { WARN_ON_ONCE(1); dl_se->dl_yielded =3D 1; @@ -2428,11 +2438,18 @@ again: return p; } =20 +#ifdef CONFIG_SMP +static struct task_struct *pick_task_dl(struct rq *rq) +{ + return __pick_next_task_dl(rq, true); +} +#endif + static struct task_struct *pick_next_task_dl(struct rq *rq) { struct task_struct *p; =20 - p =3D pick_task_dl(rq); + p =3D __pick_next_task_dl(rq, false); if (!p) return p; =20 diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1ea5ec8..ee251ac 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8479,6 +8479,14 @@ again: cfs_rq =3D group_cfs_rq(se); } while (cfs_rq); =20 + /* + * This can be called from directly from CFS's ->pick_task() or indirectly + * from DL's ->pick_task when fair server is enabled. In the indirect cas= e, + * DL will set ->dl_server just after this function is called, so its Ok = to + * clear. In the direct case, we are picking directly so we must clear it. + */ + task_of(se)->dl_server =3D NULL; + return task_of(se); } #endif @@ -8638,7 +8646,16 @@ static bool fair_server_has_tasks(struct sched_dl_en= tity *dl_se) return !!dl_se->rq->cfs.nr_running; } =20 -static struct task_struct *fair_server_pick(struct sched_dl_entity *dl_se) +static struct task_struct *fair_server_pick_task(struct sched_dl_entity *d= l_se) +{ +#ifdef CONFIG_SMP + return pick_task_fair(dl_se->rq); +#else + return NULL; +#endif +} + +static struct task_struct *fair_server_pick_next(struct sched_dl_entity *d= l_se) { return pick_next_task_fair(dl_se->rq, NULL, NULL); } @@ -8649,7 +8666,9 @@ void fair_server_init(struct rq *rq) =20 init_dl_entity(dl_se); =20 - dl_server_init(dl_se, rq, fair_server_has_tasks, fair_server_pick); + dl_server_init(dl_se, rq, fair_server_has_tasks, fair_server_pick_next, + fair_server_pick_task); + } =20 /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index b777ac3..f7e028b 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -361,7 +361,8 @@ extern void dl_server_start(struct sched_dl_entity *dl_= se); extern void dl_server_stop(struct sched_dl_entity *dl_se); extern void dl_server_init(struct sched_dl_entity *dl_se, struct rq *rq, dl_server_has_tasks_f has_tasks, - dl_server_pick_f pick); + dl_server_pick_f pick_next, + dl_server_pick_f pick_task); =20 extern void dl_server_update_idle_time(struct rq *rq, struct task_struct *p);