[RFC PATCH 0/2] mm: continue using per-VMA lock when retrying page faults after I/O

[Barry Song]

On Fri, Nov 28, 2025 at 4:29 AM Barry Song <21cnbao at gmail.com> wrote:
>
> On Fri, Nov 28, 2025 at 3:43 AM Matthew Wilcox <willy at infradead.org> wrote:
> >
> > [dropping individuals, leaving only mailing lists.  please don't send
> > this kind of thing to so many people in future]

Apologies, I missed this one.

The output comes from ./scripts/get_maintainer.pl. If you think the group is
too large, I guess we should at least include Suren, Lorenzo, David, and
a few others in the discussion?

[...]

>
> >
> > This use case also manages to get utterly hung-up trying to do reclaim
> > today with the mmap_lock held.  SO it manifests somewhat similarly to
> > your problem (everybody ends up blocked on mmap_lock) but it has a
> > rather different root cause.

If I understand the use case correctly, I believe retrying with the per-VMA
lock would also be very helpful. Previously, we always retried using
mmap_lock, which can be difficult to acquire under heavy contention, leading
to long latency while the pages might be reclaimed. With the per-VMA lock, it
is much easier to hold and proceed with the work.

Thanks
Barry