Re: [PATCH v2 00/28] Eliminate Dying Memory Cgroup

[Harry Yoo]

On Tue, Dec 23, 2025 at 08:04:50PM +0000, Yosry Ahmed wrote:
> I think there might be a problem with non-hierarchical stats on cgroup
> v1, I brought it up previously [*]. I am not sure if this was addressed
> but I couldn't immediately find anything.

Hi, Yosry. Thanks for bringing this up!

> In short, if memory is charged to a dying cgroup at the time of
> reparenting, when the memory gets uncharged the stats updates will occur
> at the parent. This will update both hierarchical and non-hierarchical
> stats of the parent, which would corrupt the parent's non-hierarchical
> stats (because those counters were never incremented when the memory was
> charged).

Hmm, I wonder if this only applies to LRU pages.

In theory we should have this problem for NR_SLAB{UN,}RECLAIMABLE_B
because we already reparent objcgs, or am I missing something?

> [*]https://lore.kernel.org/all/CAJD7tkazvC*kZgGaV3idapQp-zPFaWBxoHwnrqTFoodHZGQcPA@xxxxxxxxxxxxxx/