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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 D946FC433DB for ; Tue, 9 Mar 2021 13:03:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 44B8265256 for ; Tue, 9 Mar 2021 13:03:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44B8265256 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9CD478D00ED; 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d=suse.com; s=susede1; t=1615295016; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XNqMJTZRcxP+so+/LPiiWfIm0sQR5ZAm8YLJEpNLBpA=; b=OZYlBwlFpHGak7XGxXHtK2D1CM1QdpWMKU+YjFdKmd2vkEIfXike8CPjufUuC/ROP9TLw8 kCz/tSxJOnMFGLDVhjNJV1jBiL5XSR4McqP4z0GILECwOkUVSk/l4NKdiOdkOY0D86T2BZ q4rGTHLHfcQwtLdwa9jf8eTTzPbAj04= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 73DEFAC17; Tue, 9 Mar 2021 13:03:36 +0000 (UTC) Date: Tue, 9 Mar 2021 14:03:35 +0100 From: Michal Hocko To: Matthew Wilcox Cc: Zhou Guanghui , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, 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: References: <20210304074053.65527-1-zhouguanghui1@huawei.com> <20210304074053.65527-3-zhouguanghui1@huawei.com> <20210308210225.GF3479805@casper.infradead.org> <20210309123255.GI3479805@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210309123255.GI3479805@casper.infradead.org> X-Stat-Signature: wxdcybkspsjf4fiajy1s1ycfkca4wiju X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: B8DCAC0007D6 Received-SPF: none (suse.com>: No applicable sender policy available) receiver=imf14; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615295013-179198 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 09-03-21 12:32:55, Matthew Wilcox wrote: > On Tue, Mar 09, 2021 at 10:02:00AM +0100, Michal Hocko wrote: [...] > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 913c2b9e5c72..d44dea2b8d22 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -3135,8 +3135,21 @@ int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order) > > if (memcg && !mem_cgroup_is_root(memcg)) { > > ret = __memcg_kmem_charge(memcg, gfp, 1 << order); > > if (!ret) { > > + int nr_pages = 1 << order; > > page->memcg_data = (unsigned long)memcg | > > MEMCG_DATA_KMEM; > > + > > + /* > > + * Compound pages are normally split or freed > > + * via their head pages so memcg_data in in the > > + * head page should be sufficient but there > > + * are exceptions to the rule (see __free_pages). > > + * Non compound pages would need to copy memcg anyway. > > + */ > > + for (i = 1; i < nr_pages; i++) { > > + struct page * p = page + i; > > + p->memcg_data = page->memcg_data > > + } > > return 0; > > I would condition this loop on if (!(gfp & __GFP_COMP)), but yes, something > along these lines. I might phrase the comment a little differently ... > > /* > * Compound pages are treated as a single unit, > * but non-compound pages can be freed individually > * so each page needs to have its memcg set to get > * the accounting right. > */ OK, I must have misunderstood your __free_pages fix then. I thought this was about compound pages. Btw. again I forgot about css ref counting so here is an updated version. diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 913c2b9e5c72..ec2c705f38fa 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3133,10 +3133,22 @@ int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order) memcg = get_mem_cgroup_from_current(); if (memcg && !mem_cgroup_is_root(memcg)) { - ret = __memcg_kmem_charge(memcg, gfp, 1 << order); + int nr_pages = 1 << order; + ret = __memcg_kmem_charge(memcg, gfp, nr_pages); if (!ret) { page->memcg_data = (unsigned long)memcg | MEMCG_DATA_KMEM; + if (nr_pages > 1) { + /* + * comment goes here + */ + for (i = 1; i < nr_pages; i++) { + struct page * p = page + i; + p->memcg_data = page->memcg_data + } + /* Head page reference from get_mem_cgroup_from_current */ + css_get_many(&memcg->css, nr_pages - 1); + } return 0; } css_put(&memcg->css); -- Michal Hocko SUSE Labs