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From: Muchun Song In-Reply-To: <20230213192922.1146370-1-roman.gushchin@linux.dev> Date: Tue, 14 Feb 2023 11:54:35 +0800 Cc: Andrew Morton , linux-kernel@vger.kernel.org, Johannes Weiner , Michal Hocko , Shakeel Butt , Dennis Zhou , Linux Memory Management List Content-Transfer-Encoding: 7bit Message-Id: References: <20230213192922.1146370-1-roman.gushchin@linux.dev> To: Roman Gushchin X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: A9A411C0005 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 8naqftt1j3u6pam1w17r84gqz1snbcu1 X-HE-Tag: 1676346916-369319 X-HE-Meta: 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 rg0jqJi6 6d0zSKvTj598QuVhaB+h4O5ghpT1ayKMAc0214h/UArFSC6gg8ZE2Rvl5czOzfj89zi86sSa8A9AVmJyMKxSr4qELVZBjq4L9/0jQEuwtG/CmaKO7SeMEtg7ntDJNkbDVW/+8q8wxFM/xHjXIXJxN86UxXrJ9fOn1HUSJ+m7Rgiw2wTY3MAOAh6bME3xcqoBVeOHir5gpQU9yqb4xq7xQI7b3I6ViEIq9c5v1LypHAd06H90= 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 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 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. Thanks.