[PATCH] loop: don't lose PF_MEMDIE

From: Hugh Dickins <hugh@veritas.com>

loop_get_buffer loses PF_MEMDIE if it's added while in loop_copy_bio: not a
high probability since it's not waiting there, but could happen, and sets a
bad example (compare with add_to_swap fixed a while back).

drivers/block/loop.c

@@ -484,7 +484,9 @@ static struct bio *loop_get_buffer(struct loop_device *lo, struct bio *rbh)
 
 		current->flags &= ~PF_MEMALLOC;
 		bio = loop_copy_bio(rbh);
-		current->flags = flags;
+		if (flags & PF_MEMALLOC)
+			current->flags |= PF_MEMALLOC;
+
 		if (bio == NULL)
 			blk_congestion_wait(WRITE, HZ/10);
 	} while (bio == NULL);