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[115.124.30.130]) by mx.google.com with ESMTPS id q145si111153oic.220.2019.01.15.15.56.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 Jan 2019 15:56:31 -0800 (PST) Received-SPF: pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.130 as permitted sender) client-ip=115.124.30.130; Authentication-Results: mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.130 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com 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 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: X-Virus-Scanned: ClamAV using ClamSMTP 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