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 X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4590FC3B187 for ; Wed, 12 Feb 2020 22:03:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C5C424650 for ; Wed, 12 Feb 2020 22:03:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581544990; bh=1+gTyPef2xsQMRjzKXxLhlnN7uH/ijwKkYHs8CXSV/Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=YjMRLK2BFCXKwuidjxLibOuDiHmYkLAllITK8dY+Lnxzbcvl3IsBeRfUPDYkf+LUX +NRmpCbyZ2RfrgUc+dS0Ym8bKZuDDut6YaL8t/nztZ6D6EZrrQ772mwOVtLwYFLsIT virXLrUJkxA8LTETzZuElScGE/CUKhW70uGvrj7M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729107AbgBLWDJ (ORCPT ); Wed, 12 Feb 2020 17:03:09 -0500 Received: from mail-qk1-f196.google.com ([209.85.222.196]:37489 "EHLO mail-qk1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727564AbgBLWDJ (ORCPT ); Wed, 12 Feb 2020 17:03:09 -0500 Received: by mail-qk1-f196.google.com with SMTP id c188so3706752qkg.4; Wed, 12 Feb 2020 14:03:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=vktZgdwHT9wecNxCGbvMxpCvSL0TwzAxN3Sq+MPR+iE=; b=nfgfpDftMtMJpWLxiSSs1X2OYcR9WlCI1amDpodmsLKxPgHkq8bnF4qf1qtxMLl199 uWMc6cYmIs/jgWcwFKkmA1JHNWG82eW/IKsMlZpt3mUHo1pedk+LHU2F5vGJTvd7qkuE fNGTvtRWPXIit3HMzALvF1UOg3gvWURxXh51WA1HcgiQsiQD6P2hroKRk0XCvfHR6Dzc dUViLRXSEg/GOVAWO3L349vTzL+TvRhuWrvH/RL4CyOMUBipTQvLtVcjhMg5rGBxSPCP gHaie3hPJkpPL/U0oSQ8fkXX54m7zGqVd3HOJjXK3WbYxhlGgnFofw7ctLXn1muu7S9S mjSg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition :content-transfer-encoding:in-reply-to; bh=vktZgdwHT9wecNxCGbvMxpCvSL0TwzAxN3Sq+MPR+iE=; b=Bevf1WQsvTnT9/37wzkjtf0pNzjoFW4Znr7v5VeCL7c6a/m0kH7FLso+bdxYX2HqKD 4QrwokQ/DtRVnMtVr+CVrKbJcmNkO4ZzOL6yKFVzXrvMSOPswB57mQCYa4LexuDWs2xB +Fchd5KLybze9yhSPTuZNqKWmfaHWvF2uweyeuGkxuYnesc50J+6CchQFnbVJLUYxZC0 k4ufVtJnICxFEsM2ztAUFD5k4HHKIMQVTdLyQ9QsYRLJgAG3tARITIli4N0JSOdiIeOo ACf1zAh9N8K5nb965xXWqy/A9u2A84XSOJlfkLXhgyv+/jcMh0NyIahAbD5TVfOmsMQu XDsA== X-Gm-Message-State: APjAAAXDjNs5hH+THHuoLM41+meE0MBhuD13ofkvjG6d927/kv9pKUHf Ukhpjye9N7redyVp30NzUbU= X-Google-Smtp-Source: APXvYqzT+6mBAxj1e5FLwLyZnqWru8muuUku/e/rxOQlawFETlZgZCjz3d0Bvp6LGi4KM4HKO8a+DA== X-Received: by 2002:a37:7a83:: with SMTP id v125mr13061546qkc.22.1581544987943; Wed, 12 Feb 2020 14:03:07 -0800 (PST) Received: from localhost ([2620:10d:c091:500::1:985a]) by smtp.gmail.com with ESMTPSA id z5sm335513qta.7.2020.02.12.14.03.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Feb 2020 14:03:07 -0800 (PST) Date: Wed, 12 Feb 2020 17:03:06 -0500 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: cgroups@vger.kernel.org, alex.shi@linux.alibaba.com, guro@fb.com, hannes@cmpxchg.org, kernel-team@android.com, linger.lee@mediatek.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mediatek@lists.infradead.org, lizefan@huawei.com, matthias.bgg@gmail.com, shuah@kernel.org, surenb@google.com, tomcherry@google.com Subject: Re: [PATCH v2 1/3] cgroup: Iterate tasks that did not finish do_exit() Message-ID: <20200212220306.GH80993@mtj.thefacebook.com> References: <20200120145635.GA30904@blackbody.suse.cz> <20200124114017.8363-1-mkoutny@suse.com> <20200124114017.8363-2-mkoutny@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200124114017.8363-2-mkoutny@suse.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 24, 2020 at 12:40:15PM +0100, Michal Koutný wrote: > PF_EXITING is set earlier than actual removal from css_set when a task > is exitting. This can confuse cgroup.procs readers who see no PF_EXITING > tasks, however, rmdir is checking against css_set membership so it can > transitionally fail with EBUSY. > > Fix this by listing tasks that weren't unlinked from css_set active > lists. > It may happen that other users of the task iterator (without > CSS_TASK_ITER_PROCS) spot a PF_EXITING task before cgroup_exit(). This > is equal to the state before commit c03cd7738a83 ("cgroup: Include dying > leaders with live threads in PROCS iterations") but it may be reviewed > later. > > Reported-by: Suren Baghdasaryan > Fixes: c03cd7738a83 ("cgroup: Include dying leaders with live threads in PROCS iterations") > Signed-off-by: Michal Koutný Applied to cgroup/for-5.6-fixes. Thanks. -- tejun