mm/page-writeback: check-before-clear PageReclaim

With the page flag sanitization patchset, an invalid usage of
ClearPageReclaim() is detected in set_page_dirty().  This can be called
from __unmap_hugepage_range(), so let's check PageReclaim() before trying
to clear it to avoid the misuse.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0372411f38fc..5daf5568b9e1 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2228,7 +2228,8 @@ int set_page_dirty(struct page *page)
                  * it will confuse readahead and make it restart the size rampup
                  * process. But it's a trivial problem.
                  */
-                ClearPageReclaim(page);
+                if (PageReclaim(page))
+                        ClearPageReclaim(page);
 #ifdef CONFIG_BLOCK
                 if (!spd)
                         spd = __set_page_dirty_buffers;