From mboxrd@z Thu Jan 1 00:00:00 1970 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 4B139C00140 for ; Mon, 15 Aug 2022 19:44:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344771AbiHOTol (ORCPT ); Mon, 15 Aug 2022 15:44:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344700AbiHOTlY (ORCPT ); Mon, 15 Aug 2022 15:41:24 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C79E65811; Mon, 15 Aug 2022 11:47:26 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A6A15B81084; Mon, 15 Aug 2022 18:47:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11A57C433C1; Mon, 15 Aug 2022 18:47:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660589243; bh=m/cZj8U6SnnRtObGLL41hNZvW4O1KjdnXBw2od3BvTU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O2g2xXbJ0S9ELeOv+nVYn9dDxwuwNyyCL3LmZcTE6T95mEc1dDBqX1Os8ZRt7qLh8 KnZGWLupkYlReZoRsge2WpX9yx/u7vWmB1hXuo3Vuw8Oj9BcU9oFwHaqM3RPITNyfU 0siAFSGjavMTqLpb+TDyUPZwHz5VXRNbBej19B60= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Waiman Long , Ingo Molnar , Juri Lelli , Sasha Levin Subject: [PATCH 5.15 656/779] sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed Date: Mon, 15 Aug 2022 20:05:00 +0200 Message-Id: <20220815180405.422575786@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180337.130757997@linuxfoundation.org> References: <20220815180337.130757997@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Waiman Long [ Upstream commit b6e8d40d43ae4dec00c8fea2593eeea3114b8f44 ] 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: ffffffff8b6648b0 : [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 >= nr_cpu_ids. Fixes: 7f51412a415d ("sched/deadline: Fix bandwidth check/update when migrating 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 Signed-off-by: Sasha Levin --- 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 ad7ff332a0ac..dcba347cbffa 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1797,7 +1797,7 @@ current_restore_flags(unsigned long orig_flags, unsigned long flags) } extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct 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 cpumask *new_mask); extern int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask); diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 31f94c6ea0a5..9c5b659db63f 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2199,7 +2199,7 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) goto out_unlock; cgroup_taskset_for_each(task, css, tset) { - ret = task_can_attach(task, cs->cpus_allowed); + ret = task_can_attach(task, cs->effective_cpus); if (ret) goto out_unlock; ret = security_task_setscheduler(task); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 154506e4d1f5..5c7937b504d2 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8741,7 +8741,7 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur, } int task_can_attach(struct task_struct *p, - const struct cpumask *cs_cpus_allowed) + const struct cpumask *cs_effective_cpus) { int ret = 0; @@ -8760,9 +8760,11 @@ int task_can_attach(struct task_struct *p, } if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, - cs_cpus_allowed)) { - int cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed); + cs_effective_cpus)) { + int cpu = cpumask_any_and(cpu_active_mask, cs_effective_cpus); + if (unlikely(cpu >= nr_cpu_ids)) + return -EINVAL; ret = dl_cpu_busy(cpu, p); } -- 2.35.1