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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY, 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 9988AC43387 for ; Tue, 15 Jan 2019 23:56:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 541552082F for ; Tue, 15 Jan 2019 23:56:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729023AbfAOX4t (ORCPT ); Tue, 15 Jan 2019 18:56:49 -0500 Received: from out30-131.freemail.mail.aliyun.com ([115.124.30.131]:36848 "EHLO out30-131.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727430AbfAOX4t (ORCPT ); Tue, 15 Jan 2019 18:56:49 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04391;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0TIJZTFz_1547596295; Received: from e19h19392.et15sqa.tbsite.net(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TIJZTFz_1547596295) by smtp.aliyun-inc.com(127.0.0.1); Wed, 16 Jan 2019 07:51:49 +0800 From: Yang Shi To: mhocko@suse.com, shakeelb@google.com, hannes@cmpxchg.org, akpm@linux-foundation.org, corbet@lwn.net Cc: yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] doc: memcontrol: fix the obsolete content about force empty Date: Wed, 16 Jan 2019 07:51:35 +0800 Message-Id: <1547596295-14085-1-git-send-email-yang.shi@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We don't do page cache reparent anymore when offlining memcg, so update force empty related content accordingly. Reviewed-by: Shakeel Butt Acked-by: Michal Hocko Cc: Johannes Weiner Signed-off-by: Yang Shi --- Documentation/cgroup-v1/memory.txt | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/Documentation/cgroup-v1/memory.txt b/Documentation/cgroup-v1/memory.txt index 3682e99..8e2cb1d 100644 --- a/Documentation/cgroup-v1/memory.txt +++ b/Documentation/cgroup-v1/memory.txt @@ -70,7 +70,7 @@ Brief summary of control files. memory.soft_limit_in_bytes # set/show soft limit of memory usage memory.stat # show various statistics memory.use_hierarchy # set/show hierarchical account enabled - memory.force_empty # trigger forced move charge to parent + memory.force_empty # trigger forced page reclaim memory.pressure_level # set memory pressure notifications memory.swappiness # set/show swappiness parameter of vmscan (See sysctl's vm.swappiness) @@ -459,8 +459,9 @@ About use_hierarchy, see Section 6. the cgroup will be reclaimed and as many pages reclaimed as possible. The typical use case for this interface is before calling rmdir(). - Because rmdir() moves all pages to parent, some out-of-use page caches can be - moved to the parent. If you want to avoid that, force_empty will be useful. + Though rmdir() offlines memcg, but the memcg may still stay there due to + charged file caches. Some out-of-use page caches may keep charged until + memory pressure happens. If you want to avoid that, force_empty will be useful. Also, note that when memory.kmem.limit_in_bytes is set the charges due to kernel pages will still be seen. This is not considered a failure and the -- 1.8.3.1