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-rw-r--r--mm/swapfile.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index f4360182760..9ce7f81c8ab 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -889,7 +889,16 @@ static int try_to_unuse(unsigned int type)
lock_page(page);
wait_on_page_writeback(page);
}
- if (PageSwapCache(page))
+
+ /*
+ * It is conceivable that a racing task removed this page from
+ * swap cache just before we acquired the page lock at the top,
+ * or while we dropped it in unuse_mm(). The page might even
+ * be back in swap cache on another swap area: that we must not
+ * delete, since it may not have been written out to swap yet.
+ */
+ if (PageSwapCache(page) &&
+ likely(page_private(page) == entry.val))
delete_from_swap_cache(page);
/*