From patchwork Mon Mar 1 16:11:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 389198 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=-18.8 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, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 783CDC433DB for ; Mon, 1 Mar 2021 20:16:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2B29864DDF for ; Mon, 1 Mar 2021 20:16:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242883AbhCAUPz (ORCPT ); Mon, 1 Mar 2021 15:15:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:37630 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235661AbhCAUFS (ORCPT ); Mon, 1 Mar 2021 15:05:18 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id B0E26651BE; Mon, 1 Mar 2021 17:58:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614621518; bh=i60qBqoPVl+WofouB6tb4SS67wcZ70FqSk7W0S+vhMk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rvKzejx/ZnLRJOrU2tA91iYiVMGAkgMb0GuAkcSnJ/Wfpq9E91+Oxb7kQ/XW+k4Fp KYX3d76bA/XM6EHqEGVpyyqyo227uvXCXURgyHdpPeMG5farK6Z6o/Ez4EKznVKr6Z sL+a373sSagGR2K5hteNN1+eK2sXhifR6i6YJ+o0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Muchun Song , Michal Hocko , Johannes Weiner , Pankaj Gupta , Roman Gushchin , Shakeel Butt , Alexey Dobriyan , Feng Tang , Hugh Dickins , Joonsoo Kim , NeilBrown , "Rafael. J. Wysocki" , Randy Dunlap , Sami Tolvanen , Vladimir Davydov , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.11 546/775] mm: memcontrol: fix NR_ANON_THPS accounting in charge moving Date: Mon, 1 Mar 2021 17:11:54 +0100 Message-Id: <20210301161228.467503274@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161201.679371205@linuxfoundation.org> References: <20210301161201.679371205@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Muchun Song [ Upstream commit b0ba3bff3e7bb6b58bb248bdd2f3d8ad52fd10c3 ] Patch series "Convert all THP vmstat counters to pages", v6. This patch series is aimed to convert all THP vmstat counters to pages. The unit of some vmstat counters are pages, some are bytes, some are HPAGE_PMD_NR, and some are KiB. When we want to expose these vmstat counters to the userspace, we have to know the unit of the vmstat counters is which one. When the unit is bytes or kB, both clearly distinguishable by the B/KB suffix. But for the THP vmstat counters, we may make mistakes. For example, the below is some bug fix for the THP vmstat counters: - 7de2e9f195b9 ("mm: memcontrol: correct the NR_ANON_THPS counter of hierarchical memcg") - The first commit in this series ("fix NR_ANON_THPS accounting in charge moving") This patch series can make the code clear. And make all the unit of the THP vmstat counters in pages. Finally, the unit of the vmstat counters are pages, kB and bytes. The B/KB suffix can tell us that the unit is bytes or kB. The rest which is without suffix are pages. In this series, I changed the following vmstat counters unit from HPAGE_PMD_NR to pages. However, there is no change to the print format of output to user space. - NR_ANON_THPS - NR_FILE_THPS - NR_SHMEM_THPS - NR_SHMEM_PMDMAPPED - NR_FILE_PMDMAPPED Doing this also can make the statistics more accuracy for the THP vmstat counters. This series is consistent with 8f182270dfec ("mm/swap.c: flush lru pvecs on compound page arrival"). Because we use struct per_cpu_nodestat to cache the vmstat counters, which leads to inaccurate statistics especially THP vmstat counters. In the systems with hundreds of processors it can be GBs of memory. For example, for a 96 CPUs system, the threshold is the maximum number of 125. And the per cpu counters can cache 23.4375 GB in total. The THP page is already a form of batched addition (it will add 512 worth of memory in one go) so skipping the batching seems like sensible. Although every THP stats update overflows the per-cpu counter, resorting to atomic global updates. But it can make the statistics more accuracy for the THP vmstat counters. From this point of view, I think that do this converting is reasonable. Thanks Hugh for mentioning this. This was inspired by Johannes and Roman. Thanks to them. This patch (of 7): The unit of NR_ANON_THPS is HPAGE_PMD_NR already. So it should inc/dec by one rather than nr_pages. Link: https://lkml.kernel.org/r/20201228164110.2838-1-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20201228164110.2838-2-songmuchun@bytedance.com Fixes: 468c398233da ("mm: memcontrol: switch to native NR_ANON_THPS counter") Signed-off-by: Muchun Song Acked-by: Michal Hocko Acked-by: Johannes Weiner Acked-by: Pankaj Gupta Reviewed-by: Roman Gushchin Reviewed-by: Shakeel Butt Cc: Alexey Dobriyan Cc: Feng Tang Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Joonsoo Kim Cc: NeilBrown Cc: Rafael. J. Wysocki Cc: Randy Dunlap Cc: Sami Tolvanen Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/memcontrol.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 913c2b9e5c72d..9f4db41d8e161 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5637,10 +5637,8 @@ static int mem_cgroup_move_account(struct page *page, __mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages); __mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages); if (PageTransHuge(page)) { - __mod_lruvec_state(from_vec, NR_ANON_THPS, - -nr_pages); - __mod_lruvec_state(to_vec, NR_ANON_THPS, - nr_pages); + __dec_lruvec_state(from_vec, NR_ANON_THPS); + __inc_lruvec_state(to_vec, NR_ANON_THPS); } }