Re: [PATCH] mm:zswap: fix zswap entry reclamation failure in two scenarios

[Chris Li]

On Sun, Nov 19, 2023 at 9:41 PM Huang, Ying <ying.huang@xxxxxxxxx> wrote:
>
> Chris Li <chrisl@xxxxxxxxxx> writes:
>
> > On Sun, Nov 19, 2023 at 7:20 PM Huang, Ying <ying.huang@xxxxxxxxx> wrote:
>
> Per my understanding, memcg uncharging happens in
>
> swapcache_free_entries()
>   swap_entry_free()
>     mem_cgroup_uncharge_swap()
>
> The swap entries are uncharged one-by-one, not

Yes. That matches my understanding as well.
I think I am using the term "batching" very loosely. My bad and thanks
for the clarification.

I am referring to the fact that in most cases, the free_swap_slot()
does not perform uncharge.
It is grouped together with other entries to uncharge together inside
swapcache_free_entries(). Yes, the uncharge itself is done by a for
loop page by page. No batching in the for loop. BTW, Not all uncharges
can be batched, because they can come from different memcg.

Chris