HWPOISON: Use new shake_page in memory_failure

shake_page handles more types of page caches than
the much simpler lru_add_drain_all:

- slab (quite inefficiently for now)
- any other caches with a shrinker callback
- per cpu page allocator pages
- per CPU LRU

Use this call to try to turn pages into free or LRU pages.
Then handle the case of the page becoming free after drain everything.
Signed-off-by: Andi Kleen <ak@linux.intel.com>

mm/memory-failure.c

@@ -936,8 +936,15 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
 	 * walked by the page reclaim code, however that's not a big loss.
 	 */
 	if (!PageLRU(p))
-		lru_add_drain_all();
+		shake_page(p);
 	if (!PageLRU(p)) {
+		/*
+		 * shake_page could have turned it free.
+		 */
+		if (is_free_buddy_page(p)) {
+			action_result(pfn, "free buddy, 2nd try", DELAYED);
+			return 0;
+		}
 		action_result(pfn, "non LRU", IGNORED);
 		put_page(p);
 		return -EBUSY;