mm: switch gup_hugepte to use try_get_compound_head

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.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Christoph Hellwig <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: David Miller <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Khalid Aziz <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Rich Felker <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/gup.c b/mm/gup.c
index 2f8bf7a71c74..7763abd16405 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;
 	}