[PATCH v4 1/6] filemap: check compound_head(page)->mapping in filemap_fault()

From: Song Liu
Date: Thu Jun 20 2019 - 13:28:16 EST


Currently, filemap_fault() avoids trace 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>
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 df2006ba0cfa..f5b79a43946d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2517,7 +2517,7 @@ 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