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From: Roman Gushchin To: Andrew Morton , Johannes Weiner , Michal Hocko Cc: Muchun Song , Johannes Weiner , Michal Hocko , Shakeel Butt , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 00/14] mm: memcg: separate legacy cgroup v1 code and put under config option Message-ID: References: <20240528202101.3099300-1-roman.gushchin@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240528202101.3099300-1-roman.gushchin@linux.dev> X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 2FE7A20003 X-Rspam-User: X-Stat-Signature: 11aiu1tprpju4i1pu3kfo43wn4gocai5 X-HE-Tag: 1717443306-732626 X-HE-Meta: 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 uPcTIBPv 7jsiCorR9rFXDvFoGGwkSxIyglCDff51v2SKCPxtUOzRrKqWjD8q/M3OjCR/0/bcNrliUh55uLxRXMo9wUyBAqEzpWpR2NzbclCE1AfoiqUOYAKZIlN1vLL1iC1Yv22zsc1mUzDfS93tC9ZvvrqwpMH5zfyg9w+iUlDjbgasENWTd0UuRTbwz0A2VisDzk3f8h8GNFBduVvmXenU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Johannes, Michal, friendly ping. Do you have any concerns regarding this patchset? There is a number of things which can/need to be improved/polished on top, but I'd really like to land this one first, because rebasing of such a massive patchset is time-consuming and might also introduce some silly bugs. Thanks On Tue, May 28, 2024 at 01:20:52PM -0700, Roman Gushchin wrote: > Cgroups v2 have been around for a while and many users have fully adopted them, > so they never use cgroups v1 features and functionality. Yet they have to "pay" > for the cgroup v1 support anyway: > 1) the kernel binary contains an unused cgroup v1 code, > 2) some code paths have additional checks which are not needed, > 3) some common structures like task_struct and mem_cgroup contain unused > cgroup v1-specific members. > > Cgroup v1's memory controller has a number of features that are not supported > by cgroup v2 and their implementation is pretty much self contained. > Most notably, these features are: soft limit reclaim, oom handling in userspace, > complicated event notification system, charge migration. Cgroup v1-specific code > in memcontrol.c is close to 4k lines in size and it's intervened with generic > and cgroup v2-specific code. It's a burden on developers and maintainers. > > This patchset aims to solve these problems by: > 1) moving cgroup v1-specific memcg code to the new mm/memcontrol-v1.c file, > 2) putting definitions shared by memcontrol.c and memcontrol-v1.c into the > mm/memcontrol-v1.h header, > 3) introducing the CONFIG_MEMCG_V1 config option, turned off by default, > 4) making memcontrol-v1.c to compile only if CONFIG_MEMCG_V1 is set. > > If CONFIG_MEMCG_V1 is not set, cgroup v1 memory controller is still available > for mounting, however no memory-specific control knobs are present. > > This patchset is based against mm-unstable tree (b610f75d19a34), > however a version based on mm-stable can be found here: > https://github.com/rgushchin/linux/tree/memcontrol_v1.1-stable . > > rfc: > https://lwn.net/Articles/973082/ > > v1: > - switched to CONFIG_MEMCG_V1 being off by default based on LSFMMBPF > discussion [1] > - switched to memcg1_ prefix (Johannes) > - many minor fixes > - dropped patches which put struct memcg members under CONFIG_MEMCG_V1 > (will post as a separate patchset) > > [1]: https://lwn.net/Articles/974575/