fuse: ignore PG_workingset after stealing

Fix the "fuse: trying to steal weird page" warning.

Description from Johannes Weiner:

  "Think of it as similar to PG_active. It's just another usage/heat
   indicator of file and anon pages on the reclaim LRU that, unlike
   PG_active, persists across deactivation and even reclaim (we store it in
   the page cache / swapper cache tree until the page refaults).

   So if fuse accepts pages that can legally have PG_active set,
   PG_workingset is fine too."

Reported-by: Thomas Lindroth <thomas.lindroth@gmail.com>
Fixes: 1899ad18c6 ("mm: workingset: tell cache transitions from workingset thrashing")
Cc: <stable@vger.kernel.org> # v4.20
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/dev.c

@@ -783,6 +783,7 @@ static int fuse_check_page(struct page *page)
 	       1 << PG_uptodate |
 	       1 << PG_lru |
 	       1 << PG_active |
+	       1 << PG_workingset |
 	       1 << PG_reclaim |
 	       1 << PG_waiters))) {
 		dump_page(page, "fuse: trying to steal weird page");