filemap: remove use of wait bookmarks

The original problem of the overly long list of waiters on a locked page
was solved properly by commit 9a1ea43 ("mm:
put_and_wait_on_page_locked() while page is migrated").  In the meantime,
using bookmarks for the writeback bit can cause livelocks, so we need to
stop using them.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Cc: Bin Lai <[email protected]>
Cc: Benjamin Segall <[email protected]>
Cc: Daniel Bristot de Oliveira <[email protected]>
Cc: Dietmar Eggemann <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Valentin Schneider <[email protected]>
Cc: Vincent Guittot <[email protected]>

Cc: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Matthew Wilcox (Oracle)

mm/filemap.c

@@ -1133,32 +1133,13 @@ static void folio_wake_bit(struct folio *folio, int bit_nr)
 	wait_queue_head_t *q = folio_waitqueue(folio);
 	struct wait_page_key key;
 	unsigned long flags;
-	wait_queue_entry_t bookmark;
 
 	key.folio = folio;
 	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_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);
-	}
+	__wake_up_locked_key(q, TASK_NORMAL, &key);
 
 	/*
 	 * It's possible to miss clearing waiters here, when we woke our page