[PATCH 15/16] mm: switch gup_hugepte to use try_get_compound_head

[Christoph Hellwig]

This applies the overflow fixes from 8fde12ca79aff
("mm: prevent get_user_pages() from overflowing page refcount")
to the powerpc hugepd code and brings it back in sync with the
other GUP cases.

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 mm/gup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/gup.c b/mm/gup.c
index e03c7e6b1422..6090044227f1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2006,7 +2006,8 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, 
unsigned long addr,
                refs++;
        } while (addr += PAGE_SIZE, addr != end);
 
-       if (!page_cache_add_speculative(head, refs)) {
+       head = try_get_compound_head(head, refs);
+       if (!head) {
                *nr -= refs;
                return 0;
        }
-- 
2.20.1