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 9944FC433EF for ; Mon, 14 Feb 2022 20:58:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229992AbiBNU6M (ORCPT ); Mon, 14 Feb 2022 15:58:12 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:48476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229882AbiBNU6E (ORCPT ); Mon, 14 Feb 2022 15:58:04 -0500 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 68E1911EF08; Mon, 14 Feb 2022 12:57:27 -0800 (PST) Received: by mail-pf1-x429.google.com with SMTP id g1so11521631pfv.1; Mon, 14 Feb 2022 12:57:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=8eI79aPTVtqYQhM0bTcpnqJ4UdG4+AWyiT8hNcdyv7Q=; b=ZSV4ZqXKji33uFcHmgvE05zjLOm9kEVHG6oWJ7eZKZPZ4kZ2nggGrMqLqKlPL34Ek1 /u/NM4futt7QdWUDzgYKzfBFqB3ZZBZkwOMzOMhGC7cko+Qztmw8XHcfcb0gNwQq8MkU 7507ocXVBAmsp48WPhA5XpPf/bn2aWqzt0WtH8bdY9cWxbZexhWBaUs3sZd0U5bp1e3T ruHrM+VNwVpvBmLdyRZvIgDd/7i3XcHwZsLkaOtpINL3arjnaQdH3B8XpxaFk+Fyctd1 shUZRC0TnpWCQftQMjh+GxGmupgih3F576KJYbNUbrq4yUWvlv3OvixikVZXYjiUMish slvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=8eI79aPTVtqYQhM0bTcpnqJ4UdG4+AWyiT8hNcdyv7Q=; b=o3eE+CYEMxE67VxanFZkAPqsQZg+QwdShIlzmrMsDPTDscgsb+V1JTgAu2XeRlGiQo FyH4zrAW9ChQ5sJDpeVuTw+km3LV3olOdpHgBVnDIu1n2O0nIId7XDCtW61bJpQdaLLG P02SmNdoee0lNRVmA6IjkiCjTZFSpV7yS9x5sdcDwkLcyYk8C577LFWcbsnIsnjs4eE3 FMLEYCdvq7VmLFJ6sfYidkyC6c1b7ooNl3UqE4WcFTPoviC9o/Cer5so+I7k4QyEZYMD LP1hTjDWH1Tv3KiHEP2RPu9D8Pq/yC+lQtm/9UOlKR1laqkwBpSISYtI+PxJIuFIoldT Iw/w== X-Gm-Message-State: AOAM533ABcdnkONUWee9QGL7nG2NFhRkd61eYyqQGxOuRso8THXsMiYb 1Rp7oBCuFiaZK4v0qnvNWbRLUMxMr0s= X-Google-Smtp-Source: ABdhPJyUfTPTFZc8hUeHI+dD4bfFcL0x2ysfp78YkPhpEXIAqKojYn5U65C+/pWyd/cczefXz/Cd4w== X-Received: by 2002:a63:68c1:: with SMTP id d184mr494872pgc.405.1644868241417; Mon, 14 Feb 2022 11:50:41 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-e24f-43ff-fee6-449f.res6.spectrum.com. [2603:800c:1a02:1bae:e24f:43ff:fee6:449f]) by smtp.gmail.com with ESMTPSA id q94sm3968073pja.27.2022.02.14.11.50.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Feb 2022 11:50:41 -0800 (PST) Sender: Tejun Heo Date: Mon, 14 Feb 2022 09:50:39 -1000 From: Tejun Heo To: Zhang Qiao Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org, matthltc@us.ibm.com, bblum@google.com, menage@google.com, akpm@linux-foundation.org, longman@redhat.com, mkoutny@suse.com, zhaogongyi@huawei.com Subject: Re: [PATCH] cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug Message-ID: References: <20220121101210.84926-1-zhangqiao22@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220121101210.84926-1-zhangqiao22@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 21, 2022 at 06:12:10PM +0800, Zhang Qiao wrote: > 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") > Reported-by: Zhao Gongyi > Signed-off-by: Zhang Qiao Applied to cgroup/for-5.17-fixes w/ stable cc'd. Thanks and sorry about the delay. -- tejun