sched/wait: Introduce wakeup boomark in wake_up_page_bit
[muen/linux.git] / mm / filemap.c
index 9d21afd692b92ae243c1f404ce788048e1c4d768..8c88e186a773778c11cd1fbb986509fbb884ad06 100644 (file)
@@ -909,13 +909,33 @@ static void wake_up_page_bit(struct page *page, int bit_nr)
        wait_queue_head_t *q = page_waitqueue(page);
        struct wait_page_key key;
        unsigned long flags;
+       wait_queue_entry_t bookmark;
 
        key.page = page;
        key.bit_nr = bit_nr;
        key.page_match = 0;
 
+       bookmark.flags = 0;
+       bookmark.private = NULL;
+       bookmark.func = NULL;
+       INIT_LIST_HEAD(&bookmark.entry);
+
        spin_lock_irqsave(&q->lock, flags);
-       __wake_up_locked_key(q, TASK_NORMAL, &key);
+       __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
+
+       while (bookmark.flags & WQ_FLAG_BOOKMARK) {
+               /*
+                * Take a breather from holding the lock,
+                * allow pages that finish wake up asynchronously
+                * to acquire the lock and remove themselves
+                * from wait queue
+                */
+               spin_unlock_irqrestore(&q->lock, flags);
+               cpu_relax();
+               spin_lock_irqsave(&q->lock, flags);
+               __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
+       }
+
        /*
         * It is possible for other pages to have collided on the waitqueue
         * hash, so in that case check for a page match. That prevents a long-