From: Yulei Zhang <yuleixzhang@xxxxxxxxxxx>
Add pmd_special() check in gup_huge_pmd() to support dmem huge pmd.
GUP will return zero if enconter dmem page, and we could handle it
outside GUP routine.
Signed-off-by: Chen Zhuo <sagazchen@xxxxxxxxxxx>
Signed-off-by: Yulei Zhang <yuleixzhang@xxxxxxxxxxx>
---
mm/gup.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/gup.c b/mm/gup.c
index 726ffc5b0ea9..a8edbb6a2b2f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2440,6 +2440,10 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
return 0;
+ /* Bypass dmem huge pmd. It will be handled in outside routine. */
+ if (pmd_special(orig))
+ return 0;
+
if (pmd_devmap(orig)) {
if (unlikely(flags & FOLL_LONGTERM))
return 0;
@@ -2542,7 +2546,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
return 0;
if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) ||
- pmd_devmap(pmd))) {
+ pmd_devmap(pmd) || pmd_special(pmd))) {
/*
* NUMA hinting faults need to be handled in the GUP
* slowpath for accounting purposes and so that they
--
2.28.0
