From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Gushchin Subject: Re: [PATCH v5 03/11] mm: memcontrol: prepare objcg API for non-kmem usage Date: Fri, 10 Jun 2022 16:13:30 -0700 Message-ID: References: <20220530074919.46352-1-songmuchun@bytedance.com> <20220530074919.46352-4-songmuchun@bytedance.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1654902820; h=from:from:reply-to:subject:subject: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=TrSEiM07rzBXOnvoC0Ky3MYG75s35r1Z3atOF4M4Vgo=; b=AMOxHK6N2JOosdOfl0+XPzd/eYTQapToCZY4I1JYebewZncs47nQy7E5QzcCHFfBbNnr1d ZZ43ny9GLnosRlHAAJIxP9VYN6T0mUCdJ2T5H+/4VrFnQApaZzyHxS7RtXV/3nGaJue2Wn YZOOFxIk562TyU5GacNnmu6acEjlYkk= Content-Disposition: inline In-Reply-To: <20220530074919.46352-4-songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Muchun Song Cc: hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, duanxiongchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org, longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org On Mon, May 30, 2022 at 03:49:11PM +0800, Muchun Song wrote: > Pagecache pages are charged at the allocation time and holding a > reference to the original memory cgroup until being reclaimed. > Depending on the memory pressure, specific patterns of the page > sharing between different cgroups and the cgroup creation and > destruction rates, a large number of dying memory cgroups can be > pinned by pagecache pages. It makes the page reclaim less efficient > and wastes memory. > > We can convert LRU pages and most other raw memcg pins to the objcg > direction to fix this problem, and then the page->memcg will always > point to an object cgroup pointer. > > Therefore, the infrastructure of objcg no longer only serves > CONFIG_MEMCG_KMEM. In this patch, we move the infrastructure of the > objcg out of the scope of the CONFIG_MEMCG_KMEM so that the LRU pages > can reuse it to charge pages. > > We know that the LRU pages are not accounted at the root level. But > the page->memcg_data points to the root_mem_cgroup. So the > page->memcg_data of the LRU pages always points to a valid pointer. > But the root_mem_cgroup dose not have an object cgroup. If we use > obj_cgroup APIs to charge the LRU pages, we should set the > page->memcg_data to a root object cgroup. So we also allocate an > object cgroup for the root_mem_cgroup. > > Signed-off-by: Muchun Song > Acked-by: Johannes Weiner LGTM Acked-by: Roman Gushchin