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From: Roman Gushchin To: Muchun Song Cc: Andrew Morton , linux-kernel@vger.kernel.org, Johannes Weiner , Michal Hocko , Shakeel Butt , Dennis Zhou , Linux Memory Management List Subject: Re: [PATCH] mm: memcontrol: rename memcg_kmem_enabled() Message-ID: References: <20230213192922.1146370-1-roman.gushchin@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 23E4D1C002B X-Stat-Signature: afc6gd1sqxsz13f768usubdwtjutq8ct X-HE-Tag: 1676398804-667978 X-HE-Meta: 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 lyzVj4HR ZqGSjECCFWM9jIcyBzahM0LNkUu3We0nDIvF0sivITBFDAVAjLCQ626aBhMB00G8dxUbRns3jrwSPKHOc3TwRImaPyBu0mJWs7fhXbJUbQMBg/hIEtrQ3oBAScE32cZnKBOag84oivtc0uNxz/lHIQQF2pTOfTtI9KBHlXd90VAclytPPT1Uoqx3CouRdEQ7DjBsfyPxZgY5KbLufveMmSvjIeVRUrWhlHwcL 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, Feb 14, 2023 at 11:54:35AM +0800, Muchun Song wrote: > > > > On Feb 14, 2023, at 03:29, Roman Gushchin wrote: > > > > Currently there are two kmem-related helper functions with a confusing > > semantics: memcg_kmem_enabled() and mem_cgroup_kmem_disabled(). > > > > The problem is that an obvious expectation > > memcg_kmem_enabled() == !mem_cgroup_kmem_disabled(), > > can be false. > > > > mem_cgroup_kmem_disabled() is similar to mem_cgroup_disabled(): it > > returns true only if CONFIG_MEMCG_KMEM is not set or the kmem > > accounting is disabled using a boot time kernel option > > "cgroup.memory=nokmem". It never changes the value dynamically. > > > > memcg_kmem_enabled() is different: it always returns false until > > the first non-root memory cgroup will get online (assuming the kernel > > memory accounting is enabled). It's goal is to improve the performance > > on systems without the cgroupfs mounted/memory controller enabled or > > on the systems with only the root memory cgroup. > > > > To make things more obvious and avoid potential bugs, let's rename > > memcg_kmem_enabled() to memcg_kmem_online(). > > > > Signed-off-by: Roman Gushchin > > It's more clear. > > Acked-by: Muchun Song Thank you! > > BTW, I also dislike the name of mem_cgroup_kmem_disabled, it is not > harmonious with memcg_kmem_enabled since the prefix of one is "mem_cgroup", > another is "memcg". Maybe we could make them more consistent. Anyway, it > is not related to this patch. It's a pair to mem_cgroup_disabled(). Thanks!