Re: [PATCH v6 0/5] mm/page_counter: move stock from mem_cgroup to page_counter

[Michal Koutný]

Hi.

On Thu, Sep 17, 2026 at 10:57:00AM -0700, Joshua Hahn <joshua.hahnjy@xxxxxxxxx> wrote:
> 
> This is true, but this is already the behavior for vanilla memcg.
> In this series I'm hoping to preserve all existing semantics without
> changing behaviors, so I can fix this problem in a separate issue.
> 
> Specifically, in vanilla try_charge_memcg:
> 
> done_restock:
> 	if (batch > nr_pages)
> 		refill_stock(memcg, batch - nr_pages);
> 
> ...
> 			current->memcg_nr_pages_over_high += batch;
> 
> So I've just preserved the exact semantics that we used to have before.

Kudos to you for the conservative approach.

> 
> The problem isn't that big anyways though, it's a transient inflation
> in memcg_over_high and will be wiped on the next high handling run,
> and there is no effect on accounting or permanent inflations.

It reminds me [1] where stockage imprecision could even trigger OOM but
it was reportedly only visible in LTP.

HTH,
Michal

[1] https://lore.kernel.org/all/20250530151858.672391-1-mkoutny@xxxxxxxx/

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