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Thu, 12 Nov 2020 08:33:08 -0800 (PST) Date: Thu, 12 Nov 2020 11:31:19 -0500 From: Johannes Weiner To: Roman Gushchin Cc: Andrew Morton , linux-mm@kvack.org, Shakeel Butt , Michal Hocko , linux-kernel@vger.kernel.org, David Rientjes , kernel-team@fb.com, Michal Hocko Subject: Re: [PATCH v1 1/3] mm: memcg: deprecate the non-hierarchical mode Message-ID: <20201112163119.GC873621@cmpxchg.org> References: <20201110220800.929549-1-guro@fb.com> <20201110220800.929549-2-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201110220800.929549-2-guro@fb.com> 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: On Tue, Nov 10, 2020 at 02:07:58PM -0800, Roman Gushchin wrote: > The non-hierarchical cgroup v1 mode is a legacy of early days > of the memory controller and doesn't bring any value today. > However, it complicates the code and creates many edge cases > all over the memory controller code. > > It's a good time to deprecate it completely. > > Functionally this patch enabled is by default for all cgroups > and forbids switching it off. Nothing changes if cgroup v2 is used: > hierarchical mode was enforced from scratch. > > To protect the ABI memory.use_hierarchy interface is preserved > with a limited functionality: reading always returns "1", writing > of "1" passes silently, writing of any other value fails with > -EINVAL and a warning to dmesg (on the first occasion). > > Signed-off-by: Roman Gushchin > Acked-by: Michal Hocko > Reviewed-by: Shakeel Butt > Acked-by: David Rientjes ...and don't let the door hit you on the way out ;-) Acked-by: Johannes Weiner