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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 2E876C0044D for ; Mon, 16 Mar 2020 14:59:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 088C920658 for ; Mon, 16 Mar 2020 14:59:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584370744; bh=VvEOXB9/JJl3JMbmIsYJNWg/tu1gOXlFwf9HqJjBOjA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=I9v9M9/MTSh1/M5AmrY65ABmLE+0DTa16WcpJ5+W9xsuQuXa8mzdlgg4/Pl7EsUhr S1aDEhjirmxk5fUGZQDzUxT7NkKgJ9vF0AaH8Rus9QWNVeATGLpySGKxIMAm8PtEI9 i01fTIdn0jXTsGlYwBnFRGAdq4n/AEV8wlgYrH5k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731769AbgCPO7C (ORCPT ); Mon, 16 Mar 2020 10:59:02 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:32824 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731673AbgCPO7C (ORCPT ); Mon, 16 Mar 2020 10:59:02 -0400 Received: by mail-wr1-f65.google.com with SMTP id a25so21641960wrd.0; Mon, 16 Mar 2020 07:59:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=pRHZ/81/kzUik27LyIjeUOcKEhttC2wz2iMI5IMU5Lc=; b=D2Py+30p/XjRCj2aQLR65Uxb6hLEF6CVjL65nTfbB8Y7BqXBJcSTLathTnfThpF/kE UZJeHSLKhCjms3CiK88LZJJ5VA0F43A8Bs6Qk7iiXumarkhqYvI6davKI7B+4NxJnZVU 3TAMhErkU4hlRuORpQBhq3wj8qjxcYA/dIN6z9J+ovqEvcpr85EkpgGhkXdkyLBE4VRI z9TUKg39mkuWOA9HlwqQ+RB1S8ujp8mmSdTPmfL9UFUnNk/zb6ejnOIELo1MLRIO/Wju WEn2hc5o327RxY1R3Mao8yvxiio7X/d2irf1Bx7sIY/IN30OTmVs8DLQApyexDM+W/Nj DYhQ== X-Gm-Message-State: ANhLgQ2OM7F4656b8qcWSwkEutvuKW5KMGG6fuYT60dGyXuYCekgrYoD I7IQsFLkuG8ADQD3dKJThs8= X-Google-Smtp-Source: ADFU+vupN5bWVeVlVahplDj5UFn5L9wamTUU+oZUW+uE+t3SV11JzAtqbznmWnsTdoMiIlJiBl/ItQ== X-Received: by 2002:a5d:5444:: with SMTP id w4mr4679831wrv.387.1584370740577; Mon, 16 Mar 2020 07:59:00 -0700 (PDT) Received: from localhost ([37.188.132.163]) by smtp.gmail.com with ESMTPSA id s127sm31023841wmf.28.2020.03.16.07.58.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Mar 2020 07:58:59 -0700 (PDT) Date: Mon, 16 Mar 2020 15:58:59 +0100 From: Michal Hocko To: Chris Down Cc: Andrew Morton , Johannes Weiner , Tejun Heo , Roman Gushchin , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 5/6] mm, memcg: Prevent memory.swap.max load tearing Message-ID: <20200316145859.GQ11482@dhcp22.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 12-03-20 17:33:11, Chris Down wrote: > The write side of this is xchg()/smp_mb(), so that's all good. Just a > few sites missing a READ_ONCE. > > Signed-off-by: Chris Down > Cc: Andrew Morton > Cc: Johannes Weiner > Cc: Roman Gushchin > Cc: Tejun Heo > Cc: linux-mm@kvack.org > Cc: cgroups@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: kernel-team@fb.com Acked-by: Michal Hocko > --- > mm/memcontrol.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index e0ed790a2a8c..57048a38c75d 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1511,7 +1511,7 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg) > if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) > pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n", > K((u64)page_counter_read(&memcg->swap)), > - K((u64)memcg->swap.max), memcg->swap.failcnt); > + K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt); > else { > pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n", > K((u64)page_counter_read(&memcg->memsw)), > @@ -1544,7 +1544,7 @@ unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg) > unsigned long swap_max; > > memsw_max = memcg->memsw.max; > - swap_max = memcg->swap.max; > + swap_max = READ_ONCE(memcg->swap.max); > swap_max = min(swap_max, (unsigned long)total_swap_pages); > max = min(max + swap_max, memsw_max); > } > @@ -7025,7 +7025,8 @@ bool mem_cgroup_swap_full(struct page *page) > return false; > > for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) > - if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.max) > + if (page_counter_read(&memcg->swap) * 2 >= > + READ_ONCE(memcg->swap.max)) > return true; > > return false; > -- > 2.25.1 > -- Michal Hocko SUSE Labs