On Wed, Apr 10, 2024 at 06:27:38PM -0700, Jane Chu wrote:
> On 4/10/2024 4:15 PM, Jane Chu wrote:
>
> > On 4/10/2024 3:21 AM, Oscar Salvador wrote:
> >
> > > On Mon, Apr 08, 2024 at 05:34:29PM -0700, Jane Chu wrote:
> > > > At this stage, 'p' is not expected to be a large page since a
> > > > _refcount has
> > > > been taken, right? So is it reasonable to replace the "if
> > > > (retry)" block
> > > > with a VM_BUG_ON warning? otherwise, if 'p' became part of a different
> > > > large folio, how to recover from here ?
> > > We might have split the THP (if it was part of), but AFAICS
> > > nothing stops the kernel to coallesce this page again into a new THP
> > > via e.g:
> > > madvise(MADV_HUGEPAGE) ?
> >
> > Good point, thanks!
>
> Come to think of it a bit more, maybe the check could be
>
> if (folio_test_large(folio) || (folio != page_folio(p))) {
>
> ? Because, 'p' could have become part of a THP after shake_folio() and
> before folio_lock(), right?
What is the mechanism for reassembling a large folio? I don't see that
code anywhere.
