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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 E3CCCC33C9E for ; Fri, 17 Jan 2020 17:28:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B24A8206E6 for ; Fri, 17 Jan 2020 17:28:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579282091; bh=hvGeQ+Dzxlp757fj59Ku226Qwv2Mkij8C8AjAZvL4ws=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=xW9JKavyI4Gnu/aAyEIyvvbyosVRxtY7N+w5QIR/qCKanGJEShJgGd9wQisCp50q+ hp3LL8VAgwUjIL4CyyEGPkkvB5RVEUxsialE832cdVPv7neJDyva54s+5PXdSW3QWn RaFNkgFtIm43uRrG9gWpL6GtfW1BmJik0IuC9lBk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728984AbgAQR2K (ORCPT ); Fri, 17 Jan 2020 12:28:10 -0500 Received: from mail-qt1-f195.google.com ([209.85.160.195]:44003 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726684AbgAQR2K (ORCPT ); Fri, 17 Jan 2020 12:28:10 -0500 Received: by mail-qt1-f195.google.com with SMTP id d18so22328496qtj.10; Fri, 17 Jan 2020 09:28:09 -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 :user-agent; bh=YJBe+PR1JTzkbV6VdX/ClFM8UuTfYuVGKNcb10Up+LM=; b=DbHiqO+e6kYuR6bMRUFqkRzJXzREnc/t8WeVUwNtwBq0US0ALqFtfBS3k8Ar5PzFae jpbiR7Ax+NvFzgNUZfzP6b4KBWdJJ8us7/sDH5Tiro8mnHYZM1bos9P/GDhAcxVHXG4b +CqRW+gbtb40Tq4JQ9+XfDuAtGc8xx7XWoPbLCDa9sXO0xSMc54OuWYlMPO3hMfg3xGs R6SRfw70eNBH9z1vinkvQf3Pkmv//DOGZzpDO/JeaaQZKfMlTJoC34/zqw6bnCacSApd hf6+skAgQQBrKH5W5od7c18HNBincCZTYsXdKlpO3ehhcjXZitzgNqPGCAFsoZlAoM4q MvUg== 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:user-agent; bh=YJBe+PR1JTzkbV6VdX/ClFM8UuTfYuVGKNcb10Up+LM=; b=dlGsDK2AVaRbvusaEwWxDibqJoeiK/AU65ivacLnjYcLGTxCD6VYhitgt2zmk+hptR MfK5Oi0TydvTAPAOfCqkA0RFxuYxHppwz0DY3K8zZDAOCrmo2XSvJ/m+pMI6IwnGzJ3y SGRJWwfxMcy8YdtctsVJvBwnB9dEEBhgpnYmAGhMnJEpQXDOwCUNl/gq5CnEuzmoJL0k /yqZPr8pRF7NKkW8KEjAUO3/EY5/P912PucbXcLVztykPCI9Xb68AjnO9Vpc8aFwyRYI jyGDqZvtzS6wVXn4eLQ8CGW9qjlt4QVINVasnkVXUJv4QvU1qyJFmUCOCtS6vNzRb+1Q jRLg== X-Gm-Message-State: APjAAAWFfcXNO2Ha9g7lMIHhylEmtT4DU5RLAyl3XBSPtrOy+d9nyvEq YV5glm5kx1vtcdMj/2m6AGU= X-Google-Smtp-Source: APXvYqz2O/xFh6ygdxVfF7TRwAgb6tMQGsH1goOEKwF730KRP0mdEDko+yi0ag0UIHTaUnjOw9qRYQ== X-Received: by 2002:aed:2150:: with SMTP id 74mr8430727qtc.323.1579282089045; Fri, 17 Jan 2020 09:28:09 -0800 (PST) Received: from localhost ([2620:10d:c091:500::1:7d10]) by smtp.gmail.com with ESMTPSA id r37sm13251937qtj.44.2020.01.17.09.28.08 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 17 Jan 2020 09:28:08 -0800 (PST) Date: Fri, 17 Jan 2020 09:28:06 -0800 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: cgroups@vger.kernel.org, Johannes Weiner , Li Zefan , alex.shi@linux.alibaba.com, guro@fb.com, 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, matthias.bgg@gmail.com, shuah@kernel.org, tomcherry@google.com Subject: Re: [PATCH 2/3] cgroup: Iterate tasks that did not finish do_exit() Message-ID: <20200117172806.GK2677547@devbig004.ftw2.facebook.com> References: <20200116043612.52782-1-surenb@google.com> <20200117151533.12381-1-mkoutny@suse.com> <20200117151533.12381-3-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: <20200117151533.12381-3-mkoutny@suse.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 17, 2020 at 04:15:32PM +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. Yeah, this looks fine to me. Any chance you can order this before the clean up so that we can mark it for -stable. Thanks. -- tejun