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Thu, 03 Sep 2026 17:56:23 +0000 X-Mizu-Trace-ID: a4bed8d3f0db8ac7 X-Migadu-Flow: FLOW_OUT Date: Thu, 3 Sep 2026 10:56:22 -0700 From: Shakeel Butt To: Hui Zhu Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Andrew Morton , David Hildenbrand , Qi Zheng , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hui Zhu Subject: Re: [PATCH v2 2/3] mm: memcg: redirect stats updates of dying memcgs for all hierarchies Message-ID: References: <0214c0228695db474b86d3b4778b681a6c47a6e2.1788169145.git.zhuhui@kylinos.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0214c0228695db474b86d3b4778b681a6c47a6e2.1788169145.git.zhuhui@kylinos.cn> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 630E1120009 X-Stat-Signature: ja9jrt9np7pf4i6c9hqmoj8ohwm7m4rq X-HE-Tag: 1788458185-981314 X-HE-Meta: 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 nU2o2BZl 0qET9bXII3cSuJGCNbUHdxu4NwtfsdNsKiZlpM8h/xxTyUQ2RPS9bk/j9gaM0ows856PKoaOFuUJ/aj0oskxFBQyhMrYMfE82htDlqXSVG7bqb2DnWf4fcAnQb5K3mIco7tLc+tuAurhgBRWxje6RpE9eCK5FM6NOEOyamtsEvUhan1c10dha7OKGTksxaYmFgBLOTahxxVBIiMukKllsIUKcdchCTpI1Js6fLsgL09ulCm3E0KjLxoOf8+oi5yhx9fxI6PGUymbAXLc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 31, 2026 at 05:46:10PM +0800, Hui Zhu wrote: > From: Hui Zhu > > get_non_dying_memcg_start() redirects the stat updates of a dying memcg to > its closest non-dying ancestor, but only on cgroup v1; on cgroup v2 the > stats keep being accounted to the dying memcg itself. > > The previous patch restored lruvec_page_state_local() in > count_shadow_nodes(), which reads those state_locals on cgroup v2 too, so > apply the redirection to all hierarchies. Offlining is rare, so the added > cost on the stat update fast path is limited to an rcu_read_lock() and a > css_is_dying() check; the upward walk happens only while a memcg is dying. > > Signed-off-by: Hui Zhu Please CC to stable and add a sentence on user visible impact of the bug in the commit message. With that: Acked-by: Shakeel Butt