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=-18.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 A7116C4338F for ; Mon, 2 Aug 2021 13:32:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8907660FA0 for ; Mon, 2 Aug 2021 13:32:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233857AbhHBNcb (ORCPT ); Mon, 2 Aug 2021 09:32:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:22361 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233742AbhHBNc3 (ORCPT ); Mon, 2 Aug 2021 09:32:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1627911139; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YxGDLCphK9pn216lXXkSKE8Ac13snf8eRBNigOGCfQY=; b=LwUA1poXBpKV5QefIG2TN9hKlLe03q+vRp+SMoqwJRK87wR4unpUGWvtxpD8PmzlnkYA/G i5n7li/pxZqCxay3kjzyfS3d75wSVqCYPYqgeZszgTfjXftJBqJCQvuS24Vw9qu9ZOUNX0 aWr3Q+YaRfiBmAWFix+73S/4P7oOvhQ= Received: from mail-qv1-f69.google.com (mail-qv1-f69.google.com [209.85.219.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-464-EtgPVddVOoCzixP3IerMVw-1; Mon, 02 Aug 2021 09:32:18 -0400 X-MC-Unique: EtgPVddVOoCzixP3IerMVw-1 Received: by mail-qv1-f69.google.com with SMTP id w10-20020a0cfc4a0000b0290335dd22451dso4717991qvp.5 for ; Mon, 02 Aug 2021 06:32:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=YxGDLCphK9pn216lXXkSKE8Ac13snf8eRBNigOGCfQY=; b=eEgjCWwCVnGlib/aMMc/yZsh9C+Z8OvpcdKqEz+o++thU9bw6L4BunLg9kCLLHri8v 79AwOArFHdaDJ60JjHRwIp8P0dwP9JCOtr7AtOx/WS1NQP/9EAzLCoCPEBc3kVrGpd+R vWKpirorPg/n/xIXLNqgxYVvDwqHL01275UjzAr2NhSllKx6zTlGQE2I87kFs3LiLIcD iAyBKeMWz4U+YVSFvWD8syJSYkd+97Fdp74M2DOKlzkv+1bJzF0QbiZJaEDGHsNxq6yw 83iViZp23VCQkAu7ChHgd36bLU3cuUDUllt2tlPUrTdrYtrnzdQ6fZ509xWckl5WZjt5 p9iw== X-Gm-Message-State: AOAM532Iw80v2YA51Yg8pHI0lduDp+FaqtMNl8x3iGiEXgK2bhTbho+l ECJvKiZE/f4RsSkl42fSAcVWvh50U0gGN69Mr8Qs13leUPSt0sA/x1VgPAiKHZTaTag4PQTqBne +NnUVM8QgGQZwv19D90uw8GYS X-Received: by 2002:ac8:4f11:: with SMTP id b17mr14083638qte.33.1627911137625; Mon, 02 Aug 2021 06:32:17 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwGIz1xoKvPOqISRjUd4eV/HXaGubjZfpkkJ13bdLQELNFSuifXslmT7Q3i7tSI+D+KXlK5Dg== X-Received: by 2002:ac8:4f11:: with SMTP id b17mr14083609qte.33.1627911137439; Mon, 02 Aug 2021 06:32:17 -0700 (PDT) Received: from llong.remote.csb ([2601:191:8500:76c0::cdbc]) by smtp.gmail.com with ESMTPSA id 2sm2507742qtz.1.2021.08.02.06.32.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Aug 2021 06:32:16 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Subject: Re: [PATCH] mm/memcg: Fix incorrect flushing of lruvec data in obj_stock To: Michal Hocko Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Muchun Song , Alex Shi , Chris Down , Yafang Shao , Wei Yang , Masayoshi Mizuma , Xing Zhengjun , Matthew Wilcox References: <20210802022827.10192-1-longman@redhat.com> Message-ID: <771539d4-765c-05c7-ab19-d4cae3d29efd@redhat.com> Date: Mon, 2 Aug 2021 09:32:16 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/2/21 2:28 AM, Michal Hocko wrote: > On Sun 01-08-21 22:28:27, Waiman Long wrote: >> When mod_objcg_state() is called with a pgdat that is different from >> that in the obj_stock, the old lruvec data cached in obj_stock are >> flushed out. Unfortunately, they were flushed to the new pgdat and >> hence the wrong node, not the one cached in obj_stock. > It would be great to explicitly mention user observable problems here. I > do assume this will make slab stats skewed but the effect wouldn't be > very big, right? It is the /sys/devices/system/node/node*/meminfo that will get skewed. Not /proc/meminfo. So it is a relatively minor issue. Will update the patch to mention that. >> Fix that by flushing the data to the cached pgdat instead. >> >> Fixes: 68ac5b3c8db2 ("mm/memcg: cache vmstat data in percpu memcg_stock_pcp") >> Signed-off-by: Waiman Long > Acked-by: Michal Hocko > >> --- >> mm/memcontrol.c | 8 +++++--- >> 1 file changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index ae1f5d0cb581..881ec4ddddcd 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -3106,17 +3106,19 @@ void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, >> stock->cached_pgdat = pgdat; >> } else if (stock->cached_pgdat != pgdat) { >> /* Flush the existing cached vmstat data */ >> + struct pglist_data *oldpg = stock->cached_pgdat; >> + >> + stock->cached_pgdat = pgdat; >> if (stock->nr_slab_reclaimable_b) { >> - mod_objcg_mlstate(objcg, pgdat, NR_SLAB_RECLAIMABLE_B, >> + mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B, >> stock->nr_slab_reclaimable_b); >> stock->nr_slab_reclaimable_b = 0; >> } >> if (stock->nr_slab_unreclaimable_b) { >> - mod_objcg_mlstate(objcg, pgdat, NR_SLAB_UNRECLAIMABLE_B, >> + mod_objcg_mlstate(objcg, oldpg, NR_SLAB_UNRECLAIMABLE_B, >> stock->nr_slab_unreclaimable_b); >> stock->nr_slab_unreclaimable_b = 0; >> } >> - stock->cached_pgdat = pgdat; > Minor nit. Is there any reason to move the cached_pgdat? TBH I found the > original way better from the readability POV. Right. Will move it back to its original place. Cheers, Longman From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: Re: [PATCH] mm/memcg: Fix incorrect flushing of lruvec data in obj_stock Date: Mon, 2 Aug 2021 09:32:16 -0400 Message-ID: <771539d4-765c-05c7-ab19-d4cae3d29efd@redhat.com> References: <20210802022827.10192-1-longman@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1627911139; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YxGDLCphK9pn216lXXkSKE8Ac13snf8eRBNigOGCfQY=; b=LwUA1poXBpKV5QefIG2TN9hKlLe03q+vRp+SMoqwJRK87wR4unpUGWvtxpD8PmzlnkYA/G i5n7li/pxZqCxay3kjzyfS3d75wSVqCYPYqgeZszgTfjXftJBqJCQvuS24Vw9qu9ZOUNX0 aWr3Q+YaRfiBmAWFix+73S/4P7oOvhQ= In-Reply-To: Content-Language: en-US List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Michal Hocko Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Tejun Heo , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Shakeel Butt , Muchun Song , Alex Shi , Chris Down , Yafang Shao , Wei Yang , Masayoshi Mizuma , Xing Zhengjun , Matthew On 8/2/21 2:28 AM, Michal Hocko wrote: > On Sun 01-08-21 22:28:27, Waiman Long wrote: >> When mod_objcg_state() is called with a pgdat that is different from >> that in the obj_stock, the old lruvec data cached in obj_stock are >> flushed out. Unfortunately, they were flushed to the new pgdat and >> hence the wrong node, not the one cached in obj_stock. > It would be great to explicitly mention user observable problems here. I > do assume this will make slab stats skewed but the effect wouldn't be > very big, right? It is the /sys/devices/system/node/node*/meminfo that will get skewed. Not /proc/meminfo. So it is a relatively minor issue. Will update the patch to mention that. >> Fix that by flushing the data to the cached pgdat instead. >> >> Fixes: 68ac5b3c8db2 ("mm/memcg: cache vmstat data in percpu memcg_stock_pcp") >> Signed-off-by: Waiman Long > Acked-by: Michal Hocko > >> --- >> mm/memcontrol.c | 8 +++++--- >> 1 file changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index ae1f5d0cb581..881ec4ddddcd 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -3106,17 +3106,19 @@ void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, >> stock->cached_pgdat = pgdat; >> } else if (stock->cached_pgdat != pgdat) { >> /* Flush the existing cached vmstat data */ >> + struct pglist_data *oldpg = stock->cached_pgdat; >> + >> + stock->cached_pgdat = pgdat; >> if (stock->nr_slab_reclaimable_b) { >> - mod_objcg_mlstate(objcg, pgdat, NR_SLAB_RECLAIMABLE_B, >> + mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B, >> stock->nr_slab_reclaimable_b); >> stock->nr_slab_reclaimable_b = 0; >> } >> if (stock->nr_slab_unreclaimable_b) { >> - mod_objcg_mlstate(objcg, pgdat, NR_SLAB_UNRECLAIMABLE_B, >> + mod_objcg_mlstate(objcg, oldpg, NR_SLAB_UNRECLAIMABLE_B, >> stock->nr_slab_unreclaimable_b); >> stock->nr_slab_unreclaimable_b = 0; >> } >> - stock->cached_pgdat = pgdat; > Minor nit. Is there any reason to move the cached_pgdat? TBH I found the > original way better from the readability POV. Right. Will move it back to its original place. Cheers, Longman