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 6248BC433F5 for ; Mon, 28 Feb 2022 17:28:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235193AbiB1R2w (ORCPT ); Mon, 28 Feb 2022 12:28:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236688AbiB1R16 (ORCPT ); Mon, 28 Feb 2022 12:27:58 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5FB73888E6; Mon, 28 Feb 2022 09:27:08 -0800 (PST) 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 149C8B815AE; Mon, 28 Feb 2022 17:27:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66230C340E7; Mon, 28 Feb 2022 17:27:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646069225; bh=dM3YbWc+hniMJG+idj343cewE1ilHNBcVeEZfFdS7jg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mXJroHeDJiuMNAAE8/TzmfSDqkUz2sIjxgmPdqHZCPdECJ1GvX6zoBaiJoB9eGI7s jKZSdDaWijI8LkQxTS7Z+NAsXUwfx6+fFkfWMK1EpQ2QiCGGkqUXfLCAaOLliWkmWE NXmaV/Qhvl/GQYFsZiUq5v0rz6VWF6ehirgFAUxg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhao Gongyi , Zhang Qiao , Waiman Long , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Tejun Heo Subject: [PATCH 4.14 01/31] cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug Date: Mon, 28 Feb 2022 18:23:57 +0100 Message-Id: <20220228172159.925162848@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220228172159.515152296@linuxfoundation.org> References: <20220228172159.515152296@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore 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: Zhang Qiao commit 05c7b7a92cc87ff8d7fde189d0fade250697573c upstream. As previously discussed(https://lkml.org/lkml/2022/1/20/51), cpuset_attach() is affected with similar cpu hotplug race, as follow scenario: cpuset_attach() cpu hotplug --------------------------- ---------------------- down_write(cpuset_rwsem) guarantee_online_cpus() // (load cpus_attach) sched_cpu_deactivate set_cpu_active() // will change cpu_active_mask set_cpus_allowed_ptr(cpus_attach) __set_cpus_allowed_ptr_locked() // (if the intersection of cpus_attach and cpu_active_mask is empty, will return -EINVAL) up_write(cpuset_rwsem) To avoid races such as described above, protect cpuset_attach() call with cpu_hotplug_lock. Fixes: be367d099270 ("cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time") Cc: stable@vger.kernel.org # v2.6.32+ Reported-by: Zhao Gongyi Signed-off-by: Zhang Qiao Acked-by: Waiman Long Reviewed-by: Michal Koutný Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/cpuset.c | 2 ++ 1 file changed, 2 insertions(+) --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1532,6 +1532,7 @@ static void cpuset_attach(struct cgroup_ cgroup_taskset_first(tset, &css); cs = css_cs(css); + cpus_read_lock(); mutex_lock(&cpuset_mutex); /* prepare for attach */ @@ -1587,6 +1588,7 @@ static void cpuset_attach(struct cgroup_ wake_up(&cpuset_attach_wq); mutex_unlock(&cpuset_mutex); + cpus_read_unlock(); } /* The various types of files and directories in a cpuset file system */