Fix softlockup by removing the wait_queue flag: WQ_FLAG_BOOKMARK.
Matthew Wilcox (Oracle) (2): filemap: remove use of wait bookmarks sched: remove wait bookmarks
include/linux/wait.h | 9 +++---- kernel/sched/wait.c | 60 ++++++++------------------------------------ mm/filemap.c | 21 +--------------- 3 files changed, 14 insertions(+), 76 deletions(-)
From: "Matthew Wilcox (Oracle)" willy@infradead.org
mainline inclusion from mainline-v6.7-rc1 commit b0b598ee08f9759b70971e297cf7ddd3eaaa5245 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I93R23 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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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.
Link: https://lkml.kernel.org/r/20231010035829.544242-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Cc: Bin Lai sclaibin@gmail.com Cc: Benjamin Segall bsegall@google.com Cc: Daniel Bristot de Oliveira bristot@redhat.com Cc: Dietmar Eggemann dietmar.eggemann@arm.com Cc: Ingo Molnar mingo@redhat.com Cc: Juri Lelli juri.lelli@redhat.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Mel Gorman mgorman@suse.de Cc: Peter Zijlstra peterz@infradead.org Cc: Steven Rostedt (Google) rostedt@goodmis.org Cc: Valentin Schneider vschneid@redhat.com Cc: Vincent Guittot vincent.guittot@linaro.org
Cc: Ingo Molnar mingo@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Zizhi Wo wozizhi@huawei.com --- mm/filemap.c | 21 +-------------------- 1 file changed, 1 insertion(+), 20 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c index 3a23350e7125..da44ba00526f 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1142,32 +1142,13 @@ 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
From: "Matthew Wilcox (Oracle)" willy@infradead.org
mainline inclusion from mainline-v6.7-rc1 commit 37acade0ce8938f00d6979bd02b8043b5b7089ae category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I93R23 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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There are no users of wait bookmarks left, so simplify the wait code by removing them.
Link: https://lkml.kernel.org/r/20231010035829.544242-2-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Acked-by: Ingo Molnar mingo@kernel.org Cc: Benjamin Segall bsegall@google.com Cc: Bin Lai sclaibin@gmail.com Cc: Daniel Bristot de Oliveira bristot@redhat.com Cc: Dietmar Eggemann dietmar.eggemann@arm.com Cc: Ingo Molnar mingo@redhat.com Cc: Juri Lelli juri.lelli@redhat.com Cc: Mel Gorman mgorman@suse.de Cc: Peter Zijlstra peterz@infradead.org Cc: Steven Rostedt (Google) rostedt@goodmis.org Cc: Valentin Schneider vschneid@redhat.com Cc: Vincent Guittot vincent.guittot@linaro.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Zizhi Wo wozizhi@huawei.com --- include/linux/wait.h | 9 +++---- kernel/sched/wait.c | 60 ++++++++------------------------------------ 2 files changed, 13 insertions(+), 56 deletions(-)
diff --git a/include/linux/wait.h b/include/linux/wait.h index 5ec7739400f4..3473b663176f 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -19,10 +19,9 @@ int default_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int /* wait_queue_entry::flags */ #define WQ_FLAG_EXCLUSIVE 0x01 #define WQ_FLAG_WOKEN 0x02 -#define WQ_FLAG_BOOKMARK 0x04 -#define WQ_FLAG_CUSTOM 0x08 -#define WQ_FLAG_DONE 0x10 -#define WQ_FLAG_PRIORITY 0x20 +#define WQ_FLAG_CUSTOM 0x04 +#define WQ_FLAG_DONE 0x08 +#define WQ_FLAG_PRIORITY 0x10
/* * A single wait-queue entry structure: @@ -212,8 +211,6 @@ __remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq int __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key); void __wake_up_on_current_cpu(struct wait_queue_head *wq_head, unsigned int mode, void *key); void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key); -void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head, - unsigned int mode, void *key, wait_queue_entry_t *bookmark); void __wake_up_sync_key(struct wait_queue_head *wq_head, unsigned int mode, void *key); void __wake_up_locked_sync_key(struct wait_queue_head *wq_head, unsigned int mode, void *key); void __wake_up_locked(struct wait_queue_head *wq_head, unsigned int mode, int nr); diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c index 802d98cf2de3..51e38f5f4701 100644 --- a/kernel/sched/wait.c +++ b/kernel/sched/wait.c @@ -57,13 +57,6 @@ void remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry } EXPORT_SYMBOL(remove_wait_queue);
-/* - * Scan threshold to break wait queue walk. - * This allows a waker to take a break from holding the - * wait queue lock during the wait queue walk. - */ -#define WAITQUEUE_WALK_BREAK_CNT 64 - /* * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve @@ -78,21 +71,13 @@ EXPORT_SYMBOL(remove_wait_queue); * zero in this (rare) case, and we handle it by continuing to scan the queue. */ static int __wake_up_common(struct wait_queue_head *wq_head, unsigned int mode, - int nr_exclusive, int wake_flags, void *key, - wait_queue_entry_t *bookmark) + int nr_exclusive, int wake_flags, void *key) { wait_queue_entry_t *curr, *next; - int cnt = 0;
lockdep_assert_held(&wq_head->lock);
- if (bookmark && (bookmark->flags & WQ_FLAG_BOOKMARK)) { - curr = list_next_entry(bookmark, entry); - - list_del(&bookmark->entry); - bookmark->flags = 0; - } else - curr = list_first_entry(&wq_head->head, wait_queue_entry_t, entry); + curr = list_first_entry(&wq_head->head, wait_queue_entry_t, entry);
if (&curr->entry == &wq_head->head) return nr_exclusive; @@ -101,21 +86,11 @@ static int __wake_up_common(struct wait_queue_head *wq_head, unsigned int mode, unsigned flags = curr->flags; int ret;
- if (flags & WQ_FLAG_BOOKMARK) - continue; - ret = curr->func(curr, mode, wake_flags, key); if (ret < 0) break; if (ret && (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive) break; - - if (bookmark && (++cnt > WAITQUEUE_WALK_BREAK_CNT) && - (&next->entry != &wq_head->head)) { - bookmark->flags = WQ_FLAG_BOOKMARK; - list_add_tail(&bookmark->entry, &next->entry); - break; - } }
return nr_exclusive; @@ -125,20 +100,12 @@ static int __wake_up_common_lock(struct wait_queue_head *wq_head, unsigned int m int nr_exclusive, int wake_flags, void *key) { unsigned long flags; - wait_queue_entry_t bookmark; - int remaining = nr_exclusive; + int remaining;
- bookmark.flags = 0; - bookmark.private = NULL; - bookmark.func = NULL; - INIT_LIST_HEAD(&bookmark.entry); - - do { - spin_lock_irqsave(&wq_head->lock, flags); - remaining = __wake_up_common(wq_head, mode, remaining, - wake_flags, key, &bookmark); - spin_unlock_irqrestore(&wq_head->lock, flags); - } while (bookmark.flags & WQ_FLAG_BOOKMARK); + spin_lock_irqsave(&wq_head->lock, flags); + remaining = __wake_up_common(wq_head, mode, nr_exclusive, wake_flags, + key); + spin_unlock_irqrestore(&wq_head->lock, flags);
return nr_exclusive - remaining; } @@ -171,23 +138,16 @@ void __wake_up_on_current_cpu(struct wait_queue_head *wq_head, unsigned int mode */ void __wake_up_locked(struct wait_queue_head *wq_head, unsigned int mode, int nr) { - __wake_up_common(wq_head, mode, nr, 0, NULL, NULL); + __wake_up_common(wq_head, mode, nr, 0, NULL); } EXPORT_SYMBOL_GPL(__wake_up_locked);
void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key) { - __wake_up_common(wq_head, mode, 1, 0, key, NULL); + __wake_up_common(wq_head, mode, 1, 0, key); } EXPORT_SYMBOL_GPL(__wake_up_locked_key);
-void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head, - unsigned int mode, void *key, wait_queue_entry_t *bookmark) -{ - __wake_up_common(wq_head, mode, 1, 0, key, bookmark); -} -EXPORT_SYMBOL_GPL(__wake_up_locked_key_bookmark); - /** * __wake_up_sync_key - wake up threads blocked on a waitqueue. * @wq_head: the waitqueue @@ -233,7 +193,7 @@ EXPORT_SYMBOL_GPL(__wake_up_sync_key); void __wake_up_locked_sync_key(struct wait_queue_head *wq_head, unsigned int mode, void *key) { - __wake_up_common(wq_head, mode, 1, WF_SYNC, key, NULL); + __wake_up_common(wq_head, mode, 1, WF_SYNC, key); } EXPORT_SYMBOL_GPL(__wake_up_locked_sync_key);
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