[PATCH 2/2] xfs: disable large folio support in xfile_create

[Andrew Morton]

On Thu, 11 Jan 2024 18:22:50 -0800 "Darrick J. Wong" <djwong at kernel.org> wrote:

> On Thu, Jan 11, 2024 at 10:45:53PM +0000, Matthew Wilcox wrote:
> > On Thu, Jan 11, 2024 at 02:00:53PM -0800, Andrew Morton wrote:
> > > On Wed, 10 Jan 2024 12:04:51 -0800 "Darrick J. Wong" <djwong at kernel.org> wrote:
> > > 
> > > > > > Fixing this will require a bit of an API change, and prefeably sorting out
> > > > > > the hwpoison story for pages vs folio and where it is placed in the shmem
> > > > > > API.  For now use this one liner to disable large folios.
> > > > > > 
> > > > > > Reported-by: Darrick J. Wong <djwong at kernel.org>
> > > > > > Signed-off-by: Christoph Hellwig <hch at lst.de>
> > > > > 
> > > > > Can someone who knows more about shmem.c than I do please review
> > > > > https://lore.kernel.org/linux-xfs/20240103084126.513354-4-hch@lst.de/
> > > > > so that I can feel slightly more confident as hch and I sort through the
> > > > > xfile.c issues?
> > > > > 
> > > > > For this patch,
> > > > > Reviewed-by: Darrick J. Wong <djwong at kernel.org>
> > > > 
> > > > ...except that I'm still getting 2M THPs even with this enabled, so I
> > > > guess either we get to fix it now, or create our own private tmpfs mount
> > > > so that we can pass in huge=never, similar to what i915 does. :(
> > > 
> > > What is "this"?  Are you saying that $Subject doesn't work, or that the
> > > above-linked please-review patch doesn't work?
> > 
> > shmem pays no attention to the mapping_large_folio_support() flag,
> > so the proposed fix doesn't work.  It ought to, but it has its own way
> > of doing it that predates mapping_large_folio_support existing.
> 
> Yep.  It turned out to be easier to fix xfile.c to deal with large
> folios than I thought it would be.  Or so I think.  We'll see what
> happens on fstestscloud overnight.

Where do we stand with this?  Should I merge these two patches into
6.8-rcX, cc:stable?