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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 B5A3EC2BA1A for ; Tue, 7 Apr 2020 03:11:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7BDF120769 for ; Tue, 7 Apr 2020 03:11:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="CLkrt1qu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7BDF120769 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6343A8E0098; Mon, 6 Apr 2020 23:11:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5E34A8E0062; Mon, 6 Apr 2020 23:11:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4D3178E0098; Mon, 6 Apr 2020 23:11:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0174.hostedemail.com [216.40.44.174]) by kanga.kvack.org (Postfix) with ESMTP id 310608E0062 for ; Mon, 6 Apr 2020 23:11:50 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id EFCF4181AC217 for ; Tue, 7 Apr 2020 03:11:49 +0000 (UTC) X-FDA: 76679584338.05.scene54_ff50e207942b X-HE-Tag: scene54_ff50e207942b X-Filterd-Recvd-Size: 4694 Received: from mail-io1-f68.google.com (mail-io1-f68.google.com [209.85.166.68]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Tue, 7 Apr 2020 03:11:49 +0000 (UTC) Received: by mail-io1-f68.google.com with SMTP id h6so1830861iok.11 for ; Mon, 06 Apr 2020 20:11:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VOpgLqbR0tBxiNs3iMhk/cHL73C1yw4sqNP9Va9XOho=; b=CLkrt1quZ4kbPDpjcTtM4dRVGbGVXyufveLt3cUzq7eIrgHqUsllX9rqD2HYoDpI3P 2ZjGNSC7PxqCzV5lXDURE9WY2RkK0uwrrUXg0fFBTkp/+2Z8ZoRGJrIC4VZdntGJ2jTr WcIC96sqQRAZuXFZpYyFay/9UvgvsI/0aYwVZ8+ZhPBxnGM+dHOF5EBqbBgrT12ME0c+ eXBsKUv0sKB/sTmM/pC9IVFsHAOPLaV+BqiDXGbZZKyhBBQctkMHjZ4vZleNmTw/AuK+ QLS0GJhZKrXa8M28ri81zicHzHiUj3q2H9MSOBAyS6W2GPdruQFNcnIH/yqgVNAN0VOT WckA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VOpgLqbR0tBxiNs3iMhk/cHL73C1yw4sqNP9Va9XOho=; b=ZfrqCSjs1blSPcxuo5Be21QeYFR+ugrNmYljVEk6qujlY1/qEFJwXBIBOBhxsKDDA1 /5j/JGyr9MtBax3ZyfE/yML8/hbQsimzP+ONjlQQmMpWyIudKFQhS2b7uxIRnRaoPX3R x7sn2j4h93gT3RC2bSqGkjhHY40fuMY5malZX34qqAoyPk/Wx8TMO38whyijovlhKsyQ aGtJQQediEWlIfu1fXyLMGa8y8sprT3lSxtE50BCW6UTBDGrVJKxnGcifxygtUXqzQtE M5l2/84Z73ase5j9Mky9gbn27R15AoUapFBlR8IlxKaBIFE/gRIAok53gFwOQCy0ka7T QESw== X-Gm-Message-State: AGi0PubTCPH6lic+aUo/eyhIqKrx/MpV4QgpF/ee5xSpEKmRKnEhYk1O fgGmFy6ZfmoOkQCnTCXk/Fp2ouHQOzOuh2m79h0= X-Google-Smtp-Source: APiQypKCBecGyyq4HtucK8bLsbH6zQdmptNeSdSJOisxrtFYWJMRjEMsxRpn0NGyxqFQbVMMAt5Cz9rSIbRDjUocwrs= X-Received: by 2002:a02:2b02:: with SMTP id h2mr2442318jaa.81.1586229109056; Mon, 06 Apr 2020 20:11:49 -0700 (PDT) MIME-Version: 1.0 References: <1586192163-20099-1-git-send-email-laoar.shao@gmail.com> <20200406162343.6ae4b8f74c74bcb84d026471@linux-foundation.org> <20200406200916.2623f34403155264d8c8e9e7@linux-foundation.org> In-Reply-To: <20200406200916.2623f34403155264d8c8e9e7@linux-foundation.org> From: Yafang Shao Date: Tue, 7 Apr 2020 11:11:13 +0800 Message-ID: Subject: Re: [PATCH v3] mm, memcg: fix error return value of mem_cgroup_css_alloc() To: Andrew Morton Cc: Matthew Wilcox , Johannes Weiner , Michal Hocko , Vladimir Davydov , Linux MM Content-Type: text/plain; charset="UTF-8" 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: On Tue, Apr 7, 2020 at 11:09 AM Andrew Morton wrote: > > On Tue, 7 Apr 2020 11:02:31 +0800 Yafang Shao wrote: > > > On Tue, Apr 7, 2020 at 7:23 AM Andrew Morton wrote: > > > > > > On Tue, 7 Apr 2020 00:56:03 +0800 Yafang Shao wrote: > > > > > > > When I run my memcg testcase which creates lots of memcgs, I found > > > > there're unexpected out of memory logs while there're still enough > > > > available free memory. The error log is, > > > > mkdir: cannot create directory 'foo.65533': Cannot allocate memory > > > > > > > > The reason is when we try to create more than MEM_CGROUP_ID_MAX memcgs, an > > > > -ENOMEM errno will be set by mem_cgroup_css_alloc(), but the right errno > > > > should be -EBUSY "Device or resource busy". That is same with > > > > memcg_alloc_cache_id(). > > > > > > > > As the errno really misled me, we should make it right. After this patch, > > > > the error log will be, > > > > mkdir: cannot create directory 'foo.65533': Device or resource busy > > > > > > Thanks. > > > > > > Was a -stable backport considered? > > > > I only backported to our kernel version 4.18, but I'm not sure whether > > it will apply to -stable or not. > > Seems this issue is introduced long time ago. I will try to backport > > it to -stable. > > Should I try it based on 5.5.y and 5.6.y only ? Or all the LTS kernel > > versions ? > > What I'm asking (of you and of reviewers) is whether this issue is > sufficiently serious to require fixing in -stable kernels. The > patch merging details can be sorted out later. > > I think it is worth to cc stable, as this errno will mislead the user. Thanks Yafang