From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Davydov Subject: Re: [PATCH 03/14] net: tcp_memcontrol: properly detect ancestor socket pressure Date: Sat, 14 Nov 2015 15:45:52 +0300 Message-ID: <20151114124552.GI31308@esperanza> References: <1447371693-25143-1-git-send-email-hannes@cmpxchg.org> <1447371693-25143-4-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <1447371693-25143-4-git-send-email-hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Transfer-Encoding: 7bit To: Johannes Weiner Cc: David Miller , Andrew Morton , Tejun Heo , Michal Hocko , netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-team-b10kYP2dOMg@public.gmane.org On Thu, Nov 12, 2015 at 06:41:22PM -0500, Johannes Weiner wrote: > When charging socket memory, the code currently checks only the local > page counter for excess to determine whether the memcg is under socket > pressure. But even if the local counter is fine, one of the ancestors > could have breached its limit, which should also force this child to > enter socket pressure. This currently doesn't happen. > > Fix this by using page_counter_try_charge() first. If that fails, it > means that either the local counter or one of the ancestors are in > excess of their limit, and the child should enter socket pressure. > > Signed-off-by: Johannes Weiner Reviewed-by: Vladimir Davydov For the record: it was broken by commit 3e32cb2e0a12 ("mm: memcontrol: lockless page counters").