From nobody Sun Apr 12 00:54:37 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D736BC19F28 for ; Wed, 3 Aug 2022 08:40:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236168AbiHCIkP (ORCPT ); Wed, 3 Aug 2022 04:40:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41618 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231709AbiHCIkL (ORCPT ); Wed, 3 Aug 2022 04:40:11 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 605701CB21; Wed, 3 Aug 2022 01:40:09 -0700 (PDT) Date: Wed, 03 Aug 2022 08:40:05 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1659516007; 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=JXmHOlYXR1w8dz7T89GOgxSZ8Owasc4ZCod57g8KkMs=; b=Zp8MMsXGF27arY6+W1xL8xyabiQDbxBjJnmn7epwllx+DXIBPyfWq4P2ZemY1PF1av8FfW nBzd08jv61W+COVbYrf0x0qjZbPiHKOcjY3ktr08bIiPD2z0B6WVrgMWrT58/4ZFmqe2Qn XO2LGbQzg5YRnQv6yUhO+n9x28jpb4ofLXt6xkSUweOTnSriWc8xiwfs0y/Pb1zDZnx7d0 RJPuQN1v3tBldzFxfD88UGqm9N+st2qycxV49b98yIzUBTtqbICr3MJlqtDWPN1w8LgYzF vc2pS1EvnfjGx+LNIFYK1nBktNKHEDYGC0xx7QKDGpoPQgHxiLqovCXPGq19ig== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1659516007; 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=JXmHOlYXR1w8dz7T89GOgxSZ8Owasc4ZCod57g8KkMs=; b=2yy0m9t45FGd9foJlEffeec13f2nD5ESshKe1qTfKueRhMbV5UGj6t0FZFtKUx1NwAd9wB RuRIxiz3HsgvJRDg== From: "tip-bot2 for Waiman Long" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/urgent] sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed Cc: Waiman Long , Ingo Molnar , Juri Lelli , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20220803015451.2219567-1-longman@redhat.com> References: <20220803015451.2219567-1-longman@redhat.com> MIME-Version: 1.0 Message-ID: <165951600567.15455.17749747397311406497.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/urgent branch of tip: Commit-ID: b6e8d40d43ae4dec00c8fea2593eeea3114b8f44 Gitweb: https://git.kernel.org/tip/b6e8d40d43ae4dec00c8fea2593eeea31= 14b8f44 Author: Waiman Long AuthorDate: Tue, 02 Aug 2022 21:54:51 -04:00 Committer: Ingo Molnar CommitterDate: Wed, 03 Aug 2022 10:34:26 +02:00 sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed With cgroup v2, the cpuset's cpus_allowed mask can be empty indicating that the cpuset will just use the effective CPUs of its parent. So cpuset_can_attach() can call task_can_attach() with an empty mask. This can lead to cpumask_any_and() returns nr_cpu_ids causing the call to dl_bw_of() to crash due to percpu value access of an out of bound CPU value. For example: [80468.182258] BUG: unable to handle page fault for address: ffffffff8b664= 8b0 : [80468.191019] RIP: 0010:dl_cpu_busy+0x30/0x2b0 : [80468.207946] Call Trace: [80468.208947] cpuset_can_attach+0xa0/0x140 [80468.209953] cgroup_migrate_execute+0x8c/0x490 [80468.210931] cgroup_update_dfl_csses+0x254/0x270 [80468.211898] cgroup_subtree_control_write+0x322/0x400 [80468.212854] kernfs_fop_write_iter+0x11c/0x1b0 [80468.213777] new_sync_write+0x11f/0x1b0 [80468.214689] vfs_write+0x1eb/0x280 [80468.215592] ksys_write+0x5f/0xe0 [80468.216463] do_syscall_64+0x5c/0x80 [80468.224287] entry_SYSCALL_64_after_hwframe+0x44/0xae Fix that by using effective_cpus instead. For cgroup v1, effective_cpus is the same as cpus_allowed. For v2, effective_cpus is the real cpumask to be used by tasks within the cpuset anyway. Also update task_can_attach()'s 2nd argument name to cs_effective_cpus to reflect the change. In addition, a check is added to task_can_attach() to guard against the possibility that cpumask_any_and() may return a value >=3D nr_cpu_ids. Fixes: 7f51412a415d ("sched/deadline: Fix bandwidth check/update when migra= ting tasks between exclusive cpusets") Signed-off-by: Waiman Long Signed-off-by: Ingo Molnar Acked-by: Juri Lelli Link: https://lore.kernel.org/r/20220803015451.2219567-1-longman@redhat.com --- include/linux/sched.h | 2 +- kernel/cgroup/cpuset.c | 2 +- kernel/sched/core.c | 8 +++++--- 3 files changed, 7 insertions(+), 5 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 88b8817..6a06016 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1813,7 +1813,7 @@ current_restore_flags(unsigned long orig_flags, unsig= ned long flags) } =20 extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const stru= ct cpumask *trial); -extern int task_can_attach(struct task_struct *p, const struct cpumask *cs= _cpus_allowed); +extern int task_can_attach(struct task_struct *p, const struct cpumask *cs= _effective_cpus); #ifdef CONFIG_SMP extern void do_set_cpus_allowed(struct task_struct *p, const struct cpumas= k *new_mask); extern int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumas= k *new_mask); diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 71a4188..58aadfd 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2239,7 +2239,7 @@ static int cpuset_can_attach(struct cgroup_taskset *t= set) goto out_unlock; =20 cgroup_taskset_for_each(task, css, tset) { - ret =3D task_can_attach(task, cs->cpus_allowed); + ret =3D task_can_attach(task, cs->effective_cpus); if (ret) goto out_unlock; ret =3D security_task_setscheduler(task); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5555e49..addc3c2 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8980,7 +8980,7 @@ int cpuset_cpumask_can_shrink(const struct cpumask *c= ur, } =20 int task_can_attach(struct task_struct *p, - const struct cpumask *cs_cpus_allowed) + const struct cpumask *cs_effective_cpus) { int ret =3D 0; =20 @@ -8999,9 +8999,11 @@ int task_can_attach(struct task_struct *p, } =20 if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, - cs_cpus_allowed)) { - int cpu =3D cpumask_any_and(cpu_active_mask, cs_cpus_allowed); + cs_effective_cpus)) { + int cpu =3D cpumask_any_and(cpu_active_mask, cs_effective_cpus); =20 + if (unlikely(cpu >=3D nr_cpu_ids)) + return -EINVAL; ret =3D dl_cpu_busy(cpu, p); }