From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [Patch v2 3/3] mm/memcg: add next_mz back to soft limit tree if not reclaimed yet Date: Tue, 15 Mar 2022 09:54:34 +0100 Message-ID: References: <20220312071623.19050-1-richard.weiyang@gmail.com> <20220312071623.19050-3-richard.weiyang@gmail.com> <20220314230548.wo4colcwqxhhf3mx@master> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1647334475; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=k31i3YTYOknR6WudpStCLK3nsIiTUhJ3ISWvBqEKH3c=; b=MbRJiBppXoWjXQRAq5YT4P81gpSS9nnDeHUj39iWUP03PZNHRGvEtD9vEojB4gfNUXN5Tk q1LeMjApOhbLSoOL8PiC0wlPgYbx+84b9+vVeLizG7aHNkZNeY/f8eATrszIWFxIJgUrmx cpuR7rDMXVxNY37C7t4Yl3/HUvYFjDw= Content-Disposition: inline In-Reply-To: <20220314230548.wo4colcwqxhhf3mx@master> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Wei Yang Cc: akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org On Mon 14-03-22 23:05:48, Wei Yang wrote: > On Mon, Mar 14, 2022 at 10:41:13AM +0100, Michal Hocko wrote: > >On Sat 12-03-22 07:16:23, Wei Yang wrote: > >> When memory reclaim failed for a maximum number of attempts and we bail > >> out of the reclaim loop, we forgot to put the target mem_cgroup chosen > >> for next reclaim back to the soft limit tree. This prevented pages in > >> the mem_cgroup from being reclaimed in the future even though the > >> mem_cgroup exceeded its soft limit. > >> > >> Let's say there are two mem_cgroup and both of them exceed the soft > >> limit, while the first one is more active then the second. Since we add > >> a mem_cgroup to soft limit tree every 1024 event, the second one just > >> get a rare chance to be put on soft limit tree even it exceeds the > >> limit. > > > >yes, 1024 could be just 4MB of memory or 2GB if all the charged pages > >are THPs. So the excess can build up considerably. > > > >> As time goes on, the first mem_cgroup was kept close to its soft limit > >> due to reclaim activities, while the memory usage of the second > >> mem_cgroup keeps growing over the soft limit for a long time due to its > >> relatively rare occurrence. > >> > >> This patch adds next_mz back to prevent this sceanrio. > >> > >> Signed-off-by: Wei Yang > > > >Even though your changelog is different the change itself is identical to > >https://lore.kernel.org/linux-mm/8d35206601ccf0e1fe021d24405b2a0c2f4e052f.1613584277.git.tim.c.chen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org/ > >In those cases I would preserve the the original authorship by > >From: Tim Chen > >and add his s-o-b before yours. > > TBH I don't think this is fair. > > I didn't see his original change before I sent this patch. This is a > coincidence we found the same point for improvement. > > It hurts me if you want to change authorship. Well, if you really thinks this > is what it should be, please remove my s-o-b. OK, fair enough. -- Michal Hocko SUSE Labs