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?
