The patch titled
Subject: sched: remove wait bookmarks
has been added to the -mm mm-unstable branch. Its filename is
sched-remove-wait-bookmarks.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/sched-remove-wait-bookmarks.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: sched: remove wait bookmarks
Date: Tue, 10 Oct 2023 04:58:29 +0100
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@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Benjamin Segall <bsegall@xxxxxxxxxx>
Cc: Bin Lai <sclaibin@xxxxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/wait.h | 9 ++----
kernel/sched/wait.c | 60 ++++++-----------------------------------
2 files changed, 13 insertions(+), 56 deletions(-)
--- a/include/linux/wait.h~sched-remove-wait-bookmarks
+++ a/include/linux/wait.h
@@ -19,10 +19,9 @@ int default_wake_function(struct wait_qu
/* 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_he
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);
--- a/kernel/sched/wait.c~sched-remove-wait-bookmarks
+++ a/kernel/sched/wait.c
@@ -58,13 +58,6 @@ void remove_wait_queue(struct wait_queue
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
* number) then we wake that number of exclusive tasks, and potentially all
@@ -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_
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
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 wai
*/
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);
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-make-lock_folio_maybe_drop_mmap-vma-lock-aware.patch
mm-call-wp_page_copy-under-the-vma-lock.patch
mm-handle-shared-faults-under-the-vma-lock.patch
mm-handle-cow-faults-under-the-vma-lock.patch
mm-handle-read-faults-under-the-vma-lock.patch
mm-handle-write-faults-to-ro-pages-under-the-vma-lock.patch
iomap-hold-state_lock-over-call-to-ifs_set_range_uptodate.patch
iomap-protect-read_bytes_pending-with-the-state_lock.patch
mm-add-folio_end_read.patch
ext4-use-folio_end_read.patch
buffer-use-folio_end_read.patch
iomap-use-folio_end_read.patch
bitops-add-xor_unlock_is_negative_byte.patch
alpha-implement-xor_unlock_is_negative_byte.patch
m68k-implement-xor_unlock_is_negative_byte.patch
mips-implement-xor_unlock_is_negative_byte.patch
powerpc-implement-arch_xor_unlock_is_negative_byte-on-32-bit.patch
riscv-implement-xor_unlock_is_negative_byte.patch
s390-implement-arch_xor_unlock_is_negative_byte.patch
mm-delete-checks-for-xor_unlock_is_negative_byte.patch
mm-add-folio_xor_flags_has_waiters.patch
mm-make-__end_folio_writeback-return-void.patch
mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback.patch
filemap-remove-use-of-wait-bookmarks.patch
sched-remove-wait-bookmarks.patch
