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 <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Naoya Horiguchi

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;