Re: [PATCH 1/1] userfaultfd: do not block on locking a large folio with raised refcount

Suren Baghdasaryan
2025-02-26T18:59:17Z

On Wed, Feb 26, 2025 at 8:22 AM Suren Baghdasaryan <surenb@google.com> wrote:
>
> On Wed, Feb 26, 2025 at 8:16 AM Matthew Wilcox <willy@infradead.org> wrote:
> >
> > On Wed, Feb 26, 2025 at 08:11:25AM -0800, Suren Baghdasaryan wrote:
> > > On Wed, Feb 26, 2025 at 6:59 AM Liam R. Howlett <Liam.Howlett@oracle.com> wrote:
> > > > Reversing the locking/folio_get() is okay because of the src_ptl spin
> > > > lock, right? It might be worth saying something about it in the
> > > > comment?
> > >
> > > That is correct. We take both folio lock and refcount before we drop
> > > PTL. I'll add a comment. Thanks!
> >
> > In the commit message, not in the code, please.
>
> Ack.

I posted v2 at https://lore.kernel.org/all/20250226185510.2732648-2-surenb@google.com/
as part of a pachset which includes the fix for PTE unmapping that
Peter reported. Patchset is rebased over mm-hotfixes-unstable which
includes Barry's fix to the nearby code. This avoids merge conflicts.