From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id EA5A76B000A for ; Mon, 4 Jun 2018 08:26:13 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id h12-v6so437230wrq.2 for ; Mon, 04 Jun 2018 05:26:13 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 19-v6si170895edz.385.2018.06.04.05.26.12 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 04 Jun 2018 05:26:12 -0700 (PDT) Date: Mon, 4 Jun 2018 14:26:10 +0200 From: Michal Hocko Subject: Re: [PATCH 1/2] mm: propagate memory effective protection on setting memory.min/low Message-ID: <20180604122610.GM19202@dhcp22.suse.cz> References: <20180522132528.23769-1-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180522132528.23769-1-guro@fb.com> Sender: owner-linux-mm@kvack.org List-ID: To: Roman Gushchin Cc: linux-mm@kvack.org, kernel-team@fb.com, linux-kernel@vger.kernel.org, Johannes Weiner , Vladimir Davydov , Greg Thelen , Tejun Heo , Andrew Morton On Tue 22-05-18 14:25:27, Roman Gushchin wrote: > Explicitly propagate effective memory min/low values down by the tree. > > If there is the global memory pressure, it's not really necessary. > Effective memory guarantees will be propagated automatically > as we traverse memory cgroup tree in the reclaim path. > > But if there is no global memory pressure, effective memory protection > still matters for local (memcg-scoped) memory pressure. > So, we have to update effective limits in the subtree, > if a user changes memory.min and memory.low values. Please be explicit about the exact problem. Ideally with a memcg tree example. > Signed-off-by: Roman Gushchin > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > Cc: Greg Thelen > Cc: Tejun Heo > Cc: Andrew Morton > --- > mm/memcontrol.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index ab5673dbfc4e..b9cd0bb63759 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -5374,7 +5374,7 @@ static int memory_min_show(struct seq_file *m, void *v) > static ssize_t memory_min_write(struct kernfs_open_file *of, > char *buf, size_t nbytes, loff_t off) > { > - struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); > + struct mem_cgroup *iter, *memcg = mem_cgroup_from_css(of_css(of)); > unsigned long min; > int err; > > @@ -5385,6 +5385,11 @@ static ssize_t memory_min_write(struct kernfs_open_file *of, > > page_counter_set_min(&memcg->memory, min); > > + rcu_read_lock(); > + for_each_mem_cgroup_tree(iter, memcg) > + mem_cgroup_protected(NULL, iter); > + rcu_read_unlock(); > + > return nbytes; > } > > @@ -5404,7 +5409,7 @@ static int memory_low_show(struct seq_file *m, void *v) > static ssize_t memory_low_write(struct kernfs_open_file *of, > char *buf, size_t nbytes, loff_t off) > { > - struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); > + struct mem_cgroup *iter, *memcg = mem_cgroup_from_css(of_css(of)); > unsigned long low; > int err; > > @@ -5415,6 +5420,11 @@ static ssize_t memory_low_write(struct kernfs_open_file *of, > > page_counter_set_low(&memcg->memory, low); > > + rcu_read_lock(); > + for_each_mem_cgroup_tree(iter, memcg) > + mem_cgroup_protected(NULL, iter); > + rcu_read_unlock(); > + > return nbytes; > } > > -- > 2.14.3 -- Michal Hocko SUSE Labs