From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Yang Subject: Re: [PATCH 3/3] mm/memcg: add next_mz back if not reclaimed yet Date: Thu, 10 Mar 2022 23:55:11 +0000 Message-ID: <20220310235511.maeewfjl4k5dw576@master> References: <20220308012047.26638-1-richard.weiyang@gmail.com> <20220308012047.26638-3-richard.weiyang@gmail.com> <20220309004620.fgotfh4wsquscbfn@master> Reply-To: Wei Yang Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version :content-disposition:in-reply-to:user-agent; bh=xZ6UNijk+8fR6sxhT3uosvQMAg54vwl80TP88uESaak=; b=XM21VLJKPPRv73+hFuw4W1yLb52eqWF02QVjdDSyzl7KvtU0Rbpp6Bz84KC9pdhr+7 subfZPpcr6GULDAPlJkzxB/38Pd34zsy2PU7hxsmKEvMddHWLrxFbO5TgdsdDDvv7cFm yKuaOBOHzREJyz4podBxWUZMvSVipjhzJ11+J5014IfDz+fNuQzXAnNWGCTWYDw2/Bhv Vk7noKb8nYu2GNWZfdiwQS4bj2IZK2EcaLOqg8Vzsw580aRuXiN5xXNJl0uZ1oTOZuWJ PUv57UQYkFzLQHMw2rrqKBpiaZdAfLBoGr6TjbMCd5kCiv73ndeHtmUjZlmeM3ZEr6ig wgQw== Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michal Hocko Cc: Wei Yang , hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Tim Chen On Thu, Mar 10, 2022 at 09:59:30AM +0100, Michal Hocko wrote: >On Wed 09-03-22 14:48:46, Michal Hocko wrote: >> [Cc Tim - the patch is http://lkml.kernel.org/r/20220308012047.26638-3-richard.weiyang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org] >> >> On Wed 09-03-22 00:46:20, Wei Yang wrote: >> > On Tue, Mar 08, 2022 at 09:17:58AM +0100, Michal Hocko wrote: >> > >On Tue 08-03-22 01:20:47, Wei Yang wrote: >> > >> next_mz is removed from rb_tree, let's add it back if no reclaim has >> > >> been tried. >> > > >> > >Could you elaborate more why we need/want this? >> > > >> > >> > Per my understanding, we add back the right most node even reclaim makes no >> > progress, so it is reasonable to add back a node if we didn't get a chance to >> > do reclaim on it. >> >> Your patch sounded familiar and I can remember now. The same fix has >> been posted by Tim last year >> https://lore.kernel.org/linux-mm/8d35206601ccf0e1fe021d24405b2a0c2f4e052f.1613584277.git.tim.c.chen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org/ > >Btw. I forgot to mention yesterday. Whatever was the reason this has >slipped through cracks it would great if you could reuse the changelog >of the original patch which was more verbose and explicit about the >underlying problem. The only remaining part I would add is a description >of how serious the problem is. The removed memcg would be out of the >excess tree until further memory charges would get it back. But that can >take arbitrary amount of time. Whether that is a real problem would >depend on the workload of course but considering how coarse of a tool >the soft limit is it is possible that this is not something most users >would even notice. Got it, would send a v2. >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me