Re: [PATCH] mm/vmscan: clear hopeless kswapd when global direct reclaim makes progress

[Altan Hacigumus]

On Wed, Jul 15, 2026 at 12:12 AM Michal Hocko <mhocko@xxxxxxxx> wrote:
>
> On Tue 14-07-26 19:32:04, Altan Hacigumus wrote:
> > On Tue, Jul 14, 2026 at 4:34 AM Michal Hocko <mhocko@xxxxxxxx> wrote:
> [...]
> > [2] Also, there is one more condition I've been looking at, from the
> > Sashiko review (a theoretical corner): skip the reset while tasks are
> > throttled on pfmemalloc_wait, so that it cannot defer the hopeless
> > escape hatch in allow_direct_reclaim().
>
> I would keep this a separate patch with separate reasoning. Ideally with
> some way to trigger the behavior and prove it makes any practical
> meaning. Theoretical corner cases might backfire in this rather
> convoluted area.
>

Thanks, makes sense - will drop it from this patch.

Regarding the other suggestion in the Sashiko review, I will keep that
one in: an atomic_read() check before the atomic_xchg(), to avoid taking
the cache line exclusive for already-zero clears in kswapd_clear_hopeless().

> --
> Michal Hocko
> SUSE Labs