[PATCH v10 1/7] filemap: check compound_head(page)->mapping in filemap_fault()

[Song Liu]

Currently, filemap_fault() avoids race condition with truncate by
checking page->mapping == mapping. This does not work for compound
pages. This patch let it check compound_head(page)->mapping instead.

Acked-by: Rik van Riel <riel@xxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Song Liu <songliubraving@xxxxxx>
---
 mm/filemap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 7161fb937e78..d0bd9e585c2f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2537,7 +2537,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 		goto out_retry;
 
 	/* Did it get truncated? */
-	if (unlikely(page->mapping != mapping)) {
+	if (unlikely(compound_head(page)->mapping != mapping)) {
 		unlock_page(page);
 		put_page(page);
 		goto retry_find;
-- 
2.17.1