On Wed, Dec 07, 2022 at 01:31:30PM -0800, Andrew Morton wrote:
> On Tue, 6 Dec 2022 22:00:53 -0800 Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > From: John Starks <jostarks@xxxxxxxxxxxxx>
> >
> > For dax pud, pud_huge() returns true on x86. So the function works as long
> > as hugetlb is configured. However, dax doesn't depend on hugetlb.
> > Commit 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax") fixed
> > devmap-backed huge PMDs, but missed devmap-backed huge PUDs. Fix this as
> > well.
> >
> > This fixes the below kernel panic:
> >
> > ...
> >
> > Fixes: 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax")
>
> Feb 2019.
>
> > Signed-off-by: John Starks <jostarks@xxxxxxxxxxxxx>
> > Signed-off-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
> > ---
> > mm/gup.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/gup.c b/mm/gup.c
> > index c2c2c6d..e776540 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -2765,7 +2765,7 @@ static int gup_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr, unsigned lo
> > next = pud_addr_end(addr, end);
> > if (unlikely(!pud_present(pud)))
> > return 0;
> > - if (unlikely(pud_huge(pud))) {
> > + if (unlikely(pud_huge(pud) || pud_devmap(pud))) {
> > if (!gup_huge_pud(pud, pudp, addr, next, flags,
> > pages, nr))
> > return 0;
>
> I assume this should be backported into -stable kernels?
That would be helpful, thanks.
