4.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nitin Gupta <nitin.m.gupta@xxxxxxxxxx>
[ Upstream commit dbd2667a4fb9ce4f547982b07cd69dda127c47ea ]
The function assumes that each PMD points to head of a
huge page. This is not correct as a PMD can point to
start of any 8M region with a, say 256M, hugepage. The
fix ensures that it points to the correct head of any PMD
huge page.
Cc: Julian Calaby <julian.calaby@xxxxxxxxx>
Signed-off-by: Nitin Gupta <nitin.m.gupta@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/sparc/mm/gup.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/sparc/mm/gup.c
+++ b/arch/sparc/mm/gup.c
@@ -78,8 +78,8 @@ static int gup_huge_pmd(pmd_t *pmdp, pmd
return 0;
refs = 0;
- head = pmd_page(pmd);
- page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+ page = pmd_page(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+ head = compound_head(page);
do {
VM_BUG_ON(compound_head(page) != head);
pages[*nr] = page;