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 EF977C433F5 for ; Mon, 28 Feb 2022 17:31:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236952AbiB1RcI (ORCPT ); Mon, 28 Feb 2022 12:32:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236796AbiB1Rat (ORCPT ); Mon, 28 Feb 2022 12:30:49 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D54254195; Mon, 28 Feb 2022 09:28:35 -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 10E1DB815A6; Mon, 28 Feb 2022 17:28:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C678C340E7; Mon, 28 Feb 2022 17:28:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646069312; bh=W5B5qur26hpjJoevcD+w0AR6/wqSRLTdfabBzzG6hqM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WNRvVXnC+T6e7Qoa++CfT8aqI2mhce+/KQ7hdPrIOThcqS5MgmzJ8HKdrKK/RjkDg zfH9mMxC8sNFAJrzYJYiXsa6ODnGU4XJVShdvdhnyuGwPPlFG57IMSbojd0AP3gGDS i+IT/Dwvc4wxC1+maCy1yCDkB3RuqTBRfyydJ7B8= 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 4.19 01/34] cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug Date: Mon, 28 Feb 2022 18:24:07 +0100 Message-Id: <20220228172208.566431934@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220228172207.090703467@linuxfoundation.org> References: <20220228172207.090703467@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 @@ -1528,6 +1528,7 @@ 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 */ @@ -1583,6 +1584,7 @@ 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 */