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-rw-r--r--arch/s390/mm/gup.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index 45b405ca2567..65cb06e2af4e 100644
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -52,7 +52,7 @@ static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
unsigned long mask, result;
- struct page *head, *page;
+ struct page *head, *page, *tail;
int refs;
result = write ? 0 : _SEGMENT_ENTRY_RO;
@@ -64,6 +64,7 @@ static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
refs = 0;
head = pmd_page(pmd);
page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+ tail = page;
do {
VM_BUG_ON(compound_head(page) != head);
pages[*nr] = page;
@@ -81,6 +82,17 @@ static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
*nr -= refs;
while (refs--)
put_page(head);
+ return 0;
+ }
+
+ /*
+ * Any tail page need their mapcount reference taken before we
+ * return.
+ */
+ while (refs--) {
+ if (PageTail(tail))
+ get_huge_page_tail(tail);
+ tail++;
}
return 1;