From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kamezawa Hiroyuki Subject: Re: [patch 01/11] mm: memcg: fix compaction/migration failing due to memcg limits Date: Mon, 09 Jul 2012 11:27:53 +0900 Message-ID: <4FFA41A9.2030806@jp.fujitsu.com> References: <1341449103-1986-1-git-send-email-hannes@cmpxchg.org> <1341449103-1986-2-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1341449103-1986-2-git-send-email-hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Johannes Weiner Cc: Andrew Morton , Michal Hocko , Hugh Dickins , David Rientjes , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org (2012/07/05 9:44), Johannes Weiner wrote: > Compaction (and page migration in general) can currently be hindered > through pages being owned by memory cgroups that are at their limits > and unreclaimable. > > The reason is that the replacement page is being charged against the > limit while the page being replaced is also still charged. But this > seems unnecessary, given that only one of the two pages will still be > in use after migration finishes. > > This patch changes the memcg migration sequence so that the > replacement page is not charged. Whatever page is still in use after > successful or failed migration gets to keep the charge of the page > that was going to be replaced. > > Reported-by: David Rientjes > Signed-off-by: Johannes Weiner Acked-by: KAMEZAWA Hiroyuki