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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 3B6C5C433DB for ; Mon, 8 Mar 2021 21:02:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 587C5652B6 for ; Mon, 8 Mar 2021 21:02:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 587C5652B6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BBFD98D0079; Mon, 8 Mar 2021 16:02:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B961B8D001D; Mon, 8 Mar 2021 16:02:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A857C8D0079; Mon, 8 Mar 2021 16:02:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0083.hostedemail.com [216.40.44.83]) by kanga.kvack.org (Postfix) with ESMTP id 8F1028D001D for ; Mon, 8 Mar 2021 16:02:46 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 55E04181AF5EA for ; Mon, 8 Mar 2021 21:02:46 +0000 (UTC) X-FDA: 77897931132.27.7E22B92 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf25.hostedemail.com (Postfix) with ESMTP id 1AD536000111 for ; Mon, 8 Mar 2021 21:02:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=C0RDcISmL6coxbn097zV9gfcDqq0luPUdtiKEigF4hQ=; b=N2VsIT+wdPNzR/tbA29Er6XDgl Q+jIPHVEHrMW+PZLmIr0LhJ/vclfPxgkoJ0nX1NkCHkRpRr3L2oInFOKkLyAZ6CkITFcnx+qiZT6p DE6c3AptaPEv9T0PU8yx/ci3Uxm7CqUFalaKcmZVRQGF1IM9Lep0v4OPr0b/I47UmwRttDuFo10Iy RUSpXaLLQhCTKOHAR9XPBQc3jMhWuor+3Cxo/sStzTOFi11I2dXOS2XRpQ1I9onVixONeXEwsvoN6 A0S98AKgeY/kEMkrvrRqiObRAM4LjAEEt1tDe2yOKkjY8r1dTaOTOr4Zqw20UKbPzxRN2uoeKldOz xMvtwT+A==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lJN1F-00GGAq-Gz; Mon, 08 Mar 2021 21:02:30 +0000 Date: Mon, 8 Mar 2021 21:02:25 +0000 From: Matthew Wilcox To: Zhou Guanghui Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@suse.com, hannes@cmpxchg.org, hughd@google.com, kirill.shutemov@linux.intel.com, npiggin@gmail.com, ziy@nvidia.com, wangkefeng.wang@huawei.com, guohanjun@huawei.com, dingtianhong@huawei.com, chenweilong@huawei.com, rui.xiang@huawei.com Subject: Re: [PATCH v2 2/2] mm/memcg: set memcg when split page Message-ID: <20210308210225.GF3479805@casper.infradead.org> References: <20210304074053.65527-1-zhouguanghui1@huawei.com> <20210304074053.65527-3-zhouguanghui1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210304074053.65527-3-zhouguanghui1@huawei.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1AD536000111 X-Stat-Signature: jjgag9hp5e5c1cp9ojaqcwwf15ftwc7r Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf25; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615237355-682421 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 Thu, Mar 04, 2021 at 07:40:53AM +0000, Zhou Guanghui wrote: > As described in the split_page function comment, for the non-compound > high order page, the sub-pages must be freed individually. If the > memcg of the fisrt page is valid, the tail pages cannot be uncharged > when be freed. > > For example, when alloc_pages_exact is used to allocate 1MB continuous > physical memory, 2MB is charged(kmemcg is enabled and __GFP_ACCOUNT is > set). When make_alloc_exact free the unused 1MB and free_pages_exact > free the applied 1MB, actually, only 4KB(one page) is uncharged. > > Therefore, the memcg of the tail page needs to be set when split page. There's another place we need to do this to ... +++ b/mm/page_alloc.c @@ -5081,9 +5081,15 @@ void __free_pages(struct page *page, unsigned int order) { if (put_page_testzero(page)) free_the_page(page, order); - else if (!PageHead(page)) - while (order-- > 0) - free_the_page(page + (1 << order), order); + else if (!PageHead(page)) { + while (order-- > 0) { + struct page *tail = page + (1 << order); +#ifdef CONFIG_MEMCG + tail->memcg_data = page->memcg_data; +#endif + free_the_page(tail, order); + } + } } EXPORT_SYMBOL(__free_pages); I wonder if we shouldn't initialise memcg_data on all subsequent pages of non-compound allocations instead? Because I'm not sure this is the only place that needs to be fixed.