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From:   Song Liu <songliubraving@fb.com>
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        Song Liu <songliubraving@fb.com>
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Subject: [PATCH v9 1/6] filemap: check compound_head(page)->mapping in filemap_fault()
Date:   Mon, 24 Jun 2019 17:12:41 -0700
Message-ID: <20190625001246.685563-2-songliubraving@fb.com>
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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@surriel.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
 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