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Mercier" Cc: Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , android-mm@google.com, Minchan Kim , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: memcg: Don't periodically flush stats when memcg is disabled Message-ID: <20240126210642.GK1567330@cmpxchg.org> References: <20240126203353.1163059-1-tjmercier@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240126203353.1163059-1-tjmercier@google.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: AD0FE1C0021 X-Stat-Signature: 4wfjc41xz6isgtykccc4xe5fey73egfa X-Rspam-User: X-HE-Tag: 1706303204-454536 X-HE-Meta: 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 8WT+6VEF 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jan 26, 2024 at 08:33:52PM +0000, T.J. Mercier wrote: > The root memcg is onlined even when memcg is disabled. When it's onlined > a 2 second periodic stat flush is started, but no stat flushing is > required when memcg is disabled because there can be no child memcgs. > Most calls to flush memcg stats are avoided when memcg is disabled as a > result of the mem_cgroup_disabled check [1] added in [2], but the > periodic flushing started in mem_cgroup_css_online is not. Skip it. > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/memcontrol.c?h=v6.8-rc1#n753 > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7d7ef0a4686abe43cd76a141b340a348f45ecdf2 > > Fixes: aa48e47e3906 ("memcg: infrastructure to flush memcg stats") > Reported-by: Minchan Kim > Signed-off-by: T.J. Mercier With what Shakeel pointed out resolved: Acked-by: Johannes Weiner