diff mbox series

[v10,2/7] filemap: check compound_head(page)->mapping in pagecache_get_page()

Message ID 20190801184244.3169074-3-songliubraving@fb.com (mailing list archive)
State New, archived
Headers show
Series Enable THP for text section of non-shmem files | expand

Commit Message

Song Liu Aug. 1, 2019, 6:42 p.m. UTC 
Similar to previous patch, pagecache_get_page() 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.

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
 mm/filemap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Johannes Weiner Aug. 12, 2019, 8:33 p.m. UTC | #1 
On Thu, Aug 01, 2019 at 11:42:39AM -0700, Song Liu wrote:
> Similar to previous patch, pagecache_get_page() 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.
> 
> Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Song Liu <songliubraving@fb.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
diff mbox series

Patch

diff --git a/mm/filemap.c b/mm/filemap.c
index d0bd9e585c2f..aaee1ef96f6d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1644,7 +1644,7 @@  struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
 		}
 
 		/* Has the page been truncated? */
-		if (unlikely(page->mapping != mapping)) {
+		if (unlikely(compound_head(page)->mapping != mapping)) {
 			unlock_page(page);
 			put_page(page);
 			goto repeat;