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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 5601AC43331 for ; Thu, 7 Nov 2019 15:43:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0D32B2178F for ; Thu, 7 Nov 2019 15:43:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="rTdt1J+G" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0D32B2178F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B19726B0007; Thu, 7 Nov 2019 10:43:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id AF1366B0008; Thu, 7 Nov 2019 10:43:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A2D8A6B000A; Thu, 7 Nov 2019 10:43:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 8CF446B0007 for ; Thu, 7 Nov 2019 10:43:45 -0500 (EST) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 2F8BA181AEF1D for ; Thu, 7 Nov 2019 15:43:45 +0000 (UTC) X-FDA: 76129901610.05.pet22_3dd079cc56746 X-HE-Tag: pet22_3dd079cc56746 X-Filterd-Recvd-Size: 3717 Received: from mail-qt1-f193.google.com (mail-qt1-f193.google.com [209.85.160.193]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Thu, 7 Nov 2019 15:43:44 +0000 (UTC) Received: by mail-qt1-f193.google.com with SMTP id y39so2892273qty.0 for ; 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=S61WEnfL6YzP4RornjvoaL0IM1V0FD59QqZt1SPnTjH2NuFCxdQgyvH//j+6c5ZSQ2 vIITVCR8aNqUc2Fpakl2LLofKGScJ2/rap33f2QAXT5OnkhlTJUHsVzKIlONDCJ6mxqH r8/gAUMfVpwuE1o8CvOqyRY03p87m842zkwILKxeiPke4ddMJbz5k0V+TDCCjFdVtTj+ /BiLIDpNb1SCPgBF7sLY9KNBjPYh2p0noCO/CfHJU2qNhS+Em92HoQtN91f3mHy/CItt NPPKos6sWJEYWzOdDxF1fo3Ze5O1kHgBWxEsERp9fEs1xC/L0kBec2tN5v5kWDL6bhUS znbA== X-Gm-Message-State: APjAAAU0ci9saUFdrIR91lGmrDji9O3MEWI0lSiHNZcXF7mAfJDo2rYy TXiFRa1ITu1Hmy/h25jGk5I= 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) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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