From db81b2f1ce3dc6aa902beb8b3e45a5972cf85737 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Thu, 17 Mar 2022 12:12:49 -0400 Subject: [PATCH 1/2] 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 9a1ea439b16b ("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. Signed-off-by: Matthew Wilcox (Oracle) --- mm/filemap.c | 21 +-------------------- 1 file changed, 1 insertion(+), 20 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index b2728eb52407..bb8ec585dea8 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1151,32 +1151,13 @@ 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 is possible for other pages to have collided on the waitqueue -- 2.34.1