Re: [RFC PATCH 7/8] hugetlb: add update_and_free_page_no_sleep for irq context

Michal Hocko
2021-03-22T14:47:11Z

On Mon 22-03-21 15:42:27, Michal Hocko wrote:
[...]
> Besides that the changelog doesn't really say anything about changed
> user visible behavior change. Now if somebody decreases the GB huge pool
> from the userspace the real effect on the freed up memory will be
> postponed to some later time. That "later" is unpredictable as it
> depends on WQ utilization. We definitely need some sort of
> wait_for_inflight pages. One way to do that would be to have a dedicated
> WQ and schedule a sync work item after the pool has been shrunk and wait
> for that item.

Scratch that. It is not really clear from the patch context but after
looking at the resulting code set_max_huge_pages will use the blockable
update_and_free_page so we should be fine.

Sorry about the noise!
--
Michal Hocko
SUSE Labs