Re: [PATCH v2 2/3] mm: memcg: redirect stats updates of dying memcgs for all hierarchies

[Shakeel Butt]

On Mon, Aug 31, 2026 at 05:46:10PM +0800, Hui Zhu wrote:
> From: Hui Zhu <zhuhui@xxxxxxxxxx>
> 
> 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 <zhuhui@xxxxxxxxxx>

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 <shakeel.butt@xxxxxxxxx>