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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, 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 BC997C433DB for ; Tue, 23 Mar 2021 16:11:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6D380619AE for ; Tue, 23 Mar 2021 16:11:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D380619AE 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 D07DA6B009B; Tue, 23 Mar 2021 12:11:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CB8AE6B009C; Tue, 23 Mar 2021 12:11:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B5BDC6B009E; Tue, 23 Mar 2021 12:11:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0250.hostedemail.com [216.40.44.250]) by kanga.kvack.org (Postfix) with ESMTP id 98DD16B009B for ; Tue, 23 Mar 2021 12:11:11 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 5CC64180AD830 for ; Tue, 23 Mar 2021 16:11:11 +0000 (UTC) X-FDA: 77951628342.14.A4FCE0E Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf27.hostedemail.com (Postfix) with ESMTP id EAB7080192EE for ; Tue, 23 Mar 2021 16:11:03 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1616515863; 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=EBzFai2/9UHXdLCg+ptfPYt+b4h1PCkVbj2YlqjJF+8=; b=dhX7AXuqSadfv+l2TtEdZwG20UOhZKzHOfIDUXc1uC1dklJdwR0cpzCZr/v0yU+rMjWEMl Dc1hidPn1rhLPYxPxOz6SvEdgc/+oFMDFU0JWRGMbbYT3can7CstaOIrmNxn180qb7FmdY wfkzEvjh2zJT7GB+PIlb2KRMcbq1XLE= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 1111AADAA; Tue, 23 Mar 2021 16:11:03 +0000 (UTC) Date: Tue, 23 Mar 2021 17:11:00 +0100 From: Michal Hocko To: Muchun Song Cc: guro@fb.com, hannes@cmpxchg.org, akpm@linux-foundation.org, shakeelb@google.com, vdavydov.dev@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, duanxiongchun@bytedance.com Subject: Re: [PATCH] mm: memcontrol: fix memsw uncharge for root_mem_cgroup Message-ID: References: <20210323145653.25684-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210323145653.25684-1-songmuchun@bytedance.com> X-Stat-Signature: gskajaigjnhuozw1651jefy88sjgxwxc X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: EAB7080192EE Received-SPF: none (suse.com>: No applicable sender policy available) receiver=imf27; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616515863-385021 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 23-03-21 22:56:53, Muchun Song wrote: > The pages aren't accounted at the root level, so we cannot uncharge the > page to the memsw counter for the root memcg. Fix this. The patch is correct but I do wonder whether this matters much in the end. We shouldn't really rely on a correct page counter for the root memcg AFAICS in the kernel. We do not display the value (mem_cgroup_usage) so there shouldn't be any actual problem. Unless I am missing something make sure to spell that out in the changelog. > Fixes: 1f47b61fb407 ("mm: memcontrol: fix swap counter leak on swapout from offline cgroup") > Signed-off-by: Muchun Song Acked-by: Michal Hocko > --- > mm/memcontrol.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 533b4b31b464..7d765a106684 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7155,7 +7155,8 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) > if (!cgroup_memory_noswap && memcg != swap_memcg) { > if (!mem_cgroup_is_root(swap_memcg)) > page_counter_charge(&swap_memcg->memsw, nr_entries); > - page_counter_uncharge(&memcg->memsw, nr_entries); > + if (!mem_cgroup_is_root(memcg)) > + page_counter_uncharge(&memcg->memsw, nr_entries); > } > > /* > -- > 2.11.0 -- Michal Hocko SUSE Labs