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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=ham 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 74E93C433E0 for ; Tue, 9 Feb 2021 19:12:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BF68764EC4 for ; Tue, 9 Feb 2021 19:12:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BF68764EC4 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1B0D26B0005; Tue, 9 Feb 2021 14:12:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1628B6B006C; Tue, 9 Feb 2021 14:12:33 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 050506B006E; Tue, 9 Feb 2021 14:12:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0132.hostedemail.com [216.40.44.132]) by kanga.kvack.org (Postfix) with ESMTP id E007D6B0005 for ; Tue, 9 Feb 2021 14:12:32 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A89711852F1E8 for ; Tue, 9 Feb 2021 19:12:32 +0000 (UTC) X-FDA: 77799675744.22.ducks80_1b09f1527609 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id 8200018291092 for ; Tue, 9 Feb 2021 19:12:32 +0000 (UTC) X-HE-Tag: ducks80_1b09f1527609 X-Filterd-Recvd-Size: 3491 Received: from mail-lj1-f173.google.com (mail-lj1-f173.google.com [209.85.208.173]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Tue, 9 Feb 2021 19:12:31 +0000 (UTC) Received: by mail-lj1-f173.google.com with SMTP id b16so8131658lji.13 for ; Tue, 09 Feb 2021 11:12:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=4FXGsIN5T7fPPrN05ehbZdpVJVDuk872+BL495X4FDE=; b=YvBxOcvDEJCqlebLaBfz/mFH6WfvwNvw+jQhAqduaI6hWBxU9A7ZskYOCf8zcRNuUL LNbWWsUWHTLKYRhFQE7ZkmHbXyvJranSr8hnyxgHcM87KHuoJ9eUsuztqw3ewH1h8/DU 9YcegKtpf6/jTxL35RfgKtx9Rd1OBpJeO/ouB0m3udBtiglWVl7Lp6l3JA8RS47w9/J0 2dhI4ZOMi9bgsIRYK+d8DIvW4DTc2kMjCcTmIbo41C8RoVDL5ru3Dpa/g6a8Gvbc9xNu PW6i+H6yvplDmsMMShk7HQ2tWFn96BXZ/4i4IcP8Nqc4o2ryZiRU0xfEw8EQ6+VEYUY0 L6kw== 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=4FXGsIN5T7fPPrN05ehbZdpVJVDuk872+BL495X4FDE=; b=PLfsCDGOQNiOf78Uki1QhF7A4/bBbol01zZXWJTUyV4DK6MUa7nyjItf2bB23K4uGx PDDw4zwmZxfuqSXyQnqnURybC2wkRxA896Ujl5lQ4LvHgCad73D1VFbtIbzKFUvyOTDG kB92iqoGyT/zBILLHF/EgTYiLvSVdLNw0D0ZP8eT4Q+EZ2tYYTtvbPEaujcYSmRXU1b5 nCilQeCOnUE1BLwx2YSBZCZYYlyOGOmqWaTXFnqsjb0B5QBd4WSebuVRx62e57nQjJun C99BGv03g0qTPurn0wDpHgPl6lGDTDT3VV2/By1H2yuQENYzgKw2syovB7OS1hOMyNxp Jf/A== X-Gm-Message-State: AOAM533fYlnBLpnNQYxOmGOmj2A0uMW6EVCqx1h0TBSLHWbwWKUmDDiJ H4ZmcsVXMSwszUJW+WH8gg2JqQtogVMNn3fLZcFjxw== X-Google-Smtp-Source: ABdhPJwRFIwCydh144unLEXq/89Cii4bpddgSvF/jg/HdpgT2MwCFjxuenRx4CQBFhn3OdU+YiCwBnjOx79WfCp2jHY= X-Received: by 2002:a2e:9801:: with SMTP id a1mr16081470ljj.122.1612897950233; Tue, 09 Feb 2021 11:12:30 -0800 (PST) MIME-Version: 1.0 References: <20210209190126.97842-1-hannes@cmpxchg.org> In-Reply-To: <20210209190126.97842-1-hannes@cmpxchg.org> From: Shakeel Butt Date: Tue, 9 Feb 2021 11:12:18 -0800 Message-ID: Subject: Re: [PATCH] fs: buffer: use raw page_memcg() on locked page To: Johannes Weiner Cc: Andrew Morton , Muchun Song , Michal Hocko , Linux MM , Cgroups , LKML , Kernel Team 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, Feb 9, 2021 at 11:01 AM Johannes Weiner wrote: > > alloc_page_buffers() currently uses get_mem_cgroup_from_page() for > charging the buffers to the page owner, which does an rcu-protected > page->memcg lookup and acquires a reference. But buffer allocation has > the page lock held throughout, which pins the page to the memcg and > thereby the memcg - neither rcu nor holding an extra reference during > the allocation are necessary. Use a raw page_memcg() instead. > > This was the last user of get_mem_cgroup_from_page(), delete it. > > Reported-by: Muchun Song > Signed-off-by: Johannes Weiner Reviewed-by: Shakeel Butt