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=-3.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, 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 E54ECC4363C for ; Thu, 1 Apr 2021 17:45:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79583613A5 for ; Thu, 1 Apr 2021 17:45:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235205AbhDARmY (ORCPT ); Thu, 1 Apr 2021 13:42:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234543AbhDARh5 (ORCPT ); Thu, 1 Apr 2021 13:37:57 -0400 Received: from mail-pj1-x102b.google.com (mail-pj1-x102b.google.com [IPv6:2607:f8b0:4864:20::102b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8227CC0045E4 for ; Thu, 1 Apr 2021 07:40:36 -0700 (PDT) Received: by mail-pj1-x102b.google.com with SMTP id s21so1276023pjq.1 for ; Thu, 01 Apr 2021 07:40:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=84VhsIYUGXjP4bvTSVVhtBz5aOdDg4WLVMSSjupzcrQ=; b=n3/SBRMGVrQAHPKH8CBspegdctivbT4oLgx4A6JGVo06EHnU5N7hrWFWW0Km0ZoYpb QIV4pKNKQS+/lR4qQSAdkN0jYIAZXZGXgvrA8BuVBUpgV0JL1lVh8aZS/mD9nHv4iXXO LrJPvEyhoI+/msRLROnUYdKWX3W4YENmzJrkSQEwYbOwW+oQacQDDsk1A7YLE7K+Y8IT MZhqMUbPG+5d32JiozdF9HDqJVIcaHat4vEVmD6JgkQFDhSwrjzBOsNxrTrSCG061Uwc o1TNx0byNAcR9z2UyxaeZ6j+54jhYf4uLOmc3dEQvRdDmsiEzMzeCGYwvw9Rs03l+/cg SqrQ== 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=84VhsIYUGXjP4bvTSVVhtBz5aOdDg4WLVMSSjupzcrQ=; b=Hhlvn8NX6POEKER452BZAzqDkv80qp1utbT06VUpEfpqCvf2aRkgfD3Fdq1R8O2m3J tg5dgQcmZ88XosMS+iXmjgAvz7jwT9givLF4vXc91QvmNshQSLq642gOAvUbhww+W3Dl r7wGkQeiz0kh3wDZ6wlrdjYjExFHSBSHa9olp8vuMpD9pUkv3YoPNjbkZZRz2bCMlqtL CjeC7yeh2EcQyJnjKZVwkYpX/r773JQV9+Slb0Tz4i77D/14E57f3j5/1K/nhDlMqvd8 aTY1ukYIMENJzil8x4MaAI8FWP1ZUt/p7p6u3hc68vya0sGZgNztvQSkFBslBTKuMsSR 0GpA== X-Gm-Message-State: AOAM531kckWaPod2mbDq/VoKbRh+6NuaTOB1B4hfUC2vC7ZgjHRcGJrP Q65N4gqpdmy4tvfUoFnB6rzAzi49DVLJUgoVgIRsVQ== X-Google-Smtp-Source: ABdhPJxZ6vHJhYB8lWLeKnCmXrKCfcNJ8m/exOcGQnwLMAEZhsAo8xFwga7hZwxyYL5U6ax6PgkGcuZz4MgjyJJC+jo= X-Received: by 2002:a17:90a:d991:: with SMTP id d17mr9034123pjv.229.1617288035983; Thu, 01 Apr 2021 07:40:35 -0700 (PDT) MIME-Version: 1.0 References: <20210401093343.51299-1-songmuchun@bytedance.com> In-Reply-To: From: Muchun Song Date: Thu, 1 Apr 2021 22:39:59 +0800 Message-ID: Subject: Re: [External] Re: [PATCH v2] writeback: fix obtain a reference to a freeing memcg css To: Michal Hocko Cc: Alexander Viro , Tejun Heo , axboe@fb.com, Matthew Wilcox , linux-fsdevel , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Apr 1, 2021 at 10:37 PM Michal Hocko wrote: > > On Thu 01-04-21 21:59:13, Muchun Song wrote: > > On Thu, Apr 1, 2021 at 6:26 PM Michal Hocko wrote: > [...] > > > Even if the css ref count is not really necessary it shouldn't cause any > > > harm and it makes the code easier to understand. At least a comment > > > explaining why that is not necessary would be required without it > > > > OK. I will add a comment here to explain why we need to hold a > > ref. > > I do not think this is necessary. Taking the reference is a standard > way and I am not sure it requires a comment. I meant to say that not > having a reference should really have a comment explaining why. Very Sorry. I got it wrong, thank you for further explanation. > > Thanks! > -- > Michal Hocko > SUSE Labs