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 +++++-
mm/pagewalk.c | 2 +-
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index ad1aede..47c8197 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2470,6 +2470,10 @@ 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;
@@ -2572,7 +2576,7 @@ static int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned lo
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
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index e81640d..e7c4575 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -71,7 +71,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
do {
again:
next = pmd_addr_end(addr, end);
- if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma)) {
+ if (pmd_none(*pmd) || (!walk->vma && !walk->no_vma) || pmd_special(*pmd)) {
if (ops->pte_hole)
err = ops->pte_hole(addr, next, depth, walk);
if (err)
--
1.8.3.1
