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 638C8C5DF61 for ; Thu, 7 Nov 2019 15:43:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A07E2178F for ; Thu, 7 Nov 2019 15:43:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573141427; bh=owbRnKSf2859LGoXw/LICqOs/fqjE2ZSc0aqcK8fg3s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=JbAe8pgbxFvTEhtZM2sBT5EQPk8ZgEJdZ5zN7LN2nZkadjX8yo+09+0t2jvyfVYaS NXP0vNc3pYv6dKeXbo3l01cQnngFbBmlBOPAUjeZmq4saCtA06s8IgpXeM/aQTuW5t aXbpTLCTi6D2FFOWpOD2exKvbUOsQRBFe8wt1hz8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726877AbfKGPnq (ORCPT ); Thu, 7 Nov 2019 10:43:46 -0500 Received: from mail-qt1-f193.google.com ([209.85.160.193]:38986 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726810AbfKGPnq (ORCPT ); Thu, 7 Nov 2019 10:43:46 -0500 Received: by mail-qt1-f193.google.com with SMTP id t8so2851454qtc.6; Thu, 07 Nov 2019 07:43:44 -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:in-reply-to:user-agent; bh=mwaiGtvP4pjM/nFFuK45HtDQzJ+7MTmhsD7fO3UNaLE=; b=rTdt1J+GEp1asFTQuPZVLcym1i5w0oDHdqK+9eXSBrJuj7tdWm6FUF8DlfmazZtYqO ghii+a6FoGSHFZg7Ys67K5plupUG3MZvxdDcnM61T2Z+XSu3/paB3f2akk4aCTK0cbRi 7CWFxtSTtTLVzrgtNS9/g1A5TgCMrdM4OOEdsz4V5l7iS35AnyfsaQBFFo4lnnnP6UYu 0j+GZmDCRxHFSj7hYHPU6DydmhEF6Yo72kZruft0BxB/Xl2jgVur26PTpGZ/8OdK1nAI 9koLUWef6/HPzFUSIEKrgh46voUNO8YEWWCvNlAZxxVvyvE5IZDvc9t+F1VACtj4fj9e 8rPw== 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:in-reply-to:user-agent; bh=mwaiGtvP4pjM/nFFuK45HtDQzJ+7MTmhsD7fO3UNaLE=; b=MMqKn7+ALEfY4HBsxk0mJ89UUYOadPQbBcXoMzxhhVHErKu7qLJtF7K7YOX0wj1Dnz sf90s5cyZh1F37JgtOWjEFqSgv+tLXdiZHi6AGRfaLVrBKkVyN1E0sj/z10Zfk1bx/R0 AmnThrOuLmJhF70mhs2vq0Z0187Gl2uky5vW7mGspcrmtBqxJhfnUzwkX4Pv/g56NoS9 jZJlMDRN2k4ye5Z8r98dS7WHZ+tg7RMsDT0l9ZTaZOUOQBVWshKaK6DwMcl5rp94q97L 2TR43ifUeQ/F0F7M2Ex5ffKig3XGUty7Cp0JlJ7TaDORyYyW2bie0yOhxsjngJQPBNG4 W9lg== X-Gm-Message-State: APjAAAVRi91zwiLr52azi7qk+51S6OkVM1mzFWQPx9Uyo43oeQDsY+f9 j+M00CphfrXQji0nSnY26AI= X-Google-Smtp-Source: APXvYqwJ9bgJnSqOfuwT4NQVIu7t7ruriREekPrkgTiHagbiyhpNcODVa5lJPsXIvI+5oxoMsisDwg== X-Received: by 2002:ac8:3a21:: with SMTP id w30mr4498647qte.299.1573141424023; Thu, 07 Nov 2019 07:43:44 -0800 (PST) Received: from localhost ([2620:10d:c091:500::2:3f13]) by smtp.gmail.com with ESMTPSA id f24sm1147320qkh.81.2019.11.07.07.43.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Nov 2019 07:43:43 -0800 (PST) Date: Thu, 7 Nov 2019 07:43:41 -0800 From: Tejun Heo To: Michal Hocko Cc: Roman Gushchin , linux-mm@kvack.org, Andrew Morton , Johannes Weiner , linux-kernel@vger.kernel.org, kernel-team@fb.com, stable@vger.kernel.org Subject: Re: [PATCH 1/2] mm: memcg: switch to css_tryget() in get_mem_cgroup_from_mm() Message-ID: <20191107154341.GX3622521@devbig004.ftw2.facebook.com> References: <20191106225131.3543616-1-guro@fb.com> <20191107122125.GS8314@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191107122125.GS8314@dhcp22.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Hello, On Thu, Nov 07, 2019 at 01:21:25PM +0100, Michal Hocko wrote: > Hmm, how can we have a task in an offline memcg? I thought that any > existing task will prevent cgroup removal from proceeding. Is this some > sort of race where the task managed to disassociate from the cgroup > while there is still a binding to a memcg existing? What am I missing? The previous cgroup one was from bsd process accounting which happens after the process is marked head. This one IIUC is from core dumping path. Thanks. -- tejun