6.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> This reverts commit 0c4ce23e6323e52d0590e78825cd3c63323d7a52 which is commit a045a272d887575da17ad86d6573e82871b50c27 upstream. The workqueue patches backported to 6.8.y caused some reported regressions, so revert them for now. Reported-by: Thorsten Leemhuis <regressions@xxxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Cc: Nathan Chancellor <nathan@xxxxxxxxxx> Cc: Sasha Levin <sashal@xxxxxxxxxx> Cc: Audra Mitchell <audra@xxxxxxxxxx> Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@xxxxxxxxxxxxx/ Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/workqueue.c | 133 ++++++++++++++++++++++++++--------------------------- 1 file changed, 67 insertions(+), 66 deletions(-) --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -143,9 +143,6 @@ enum { * * WR: wq->mutex protected for writes. RCU protected for reads. * - * WO: wq->mutex protected for writes. Updated with WRITE_ONCE() and can be read - * with READ_ONCE() without locking. - * * MD: wq_mayday_lock protected. * * WD: Used internally by the watchdog. @@ -253,6 +250,7 @@ struct pool_workqueue { * is marked with WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. */ int nr_active; /* L: nr of active works */ + int max_active; /* L: max active works */ struct list_head inactive_works; /* L: inactive works */ struct list_head pwqs_node; /* WR: node on wq->pwqs */ struct list_head mayday_node; /* MD: node on wq->maydays */ @@ -300,8 +298,7 @@ struct workqueue_struct { struct worker *rescuer; /* MD: rescue worker */ int nr_drainers; /* WQ: drain in progress */ - int max_active; /* WO: max active works */ - int saved_max_active; /* WQ: saved max_active */ + int saved_max_active; /* WQ: saved pwq max_active */ struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */ @@ -1495,7 +1492,7 @@ static void pwq_dec_nr_in_flight(struct pwq->nr_active--; if (!list_empty(&pwq->inactive_works)) { /* one down, submit an inactive one */ - if (pwq->nr_active < READ_ONCE(pwq->wq->max_active)) + if (pwq->nr_active < pwq->max_active) pwq_activate_first_inactive(pwq); } } @@ -1796,13 +1793,7 @@ retry: pwq->nr_in_flight[pwq->work_color]++; work_flags = work_color_to_flags(pwq->work_color); - /* - * Limit the number of concurrently active work items to max_active. - * @work must also queue behind existing inactive work items to maintain - * ordering when max_active changes. See wq_adjust_max_active(). - */ - if (list_empty(&pwq->inactive_works) && - pwq->nr_active < READ_ONCE(pwq->wq->max_active)) { + if (likely(pwq->nr_active < pwq->max_active)) { if (list_empty(&pool->worklist)) pool->watchdog_ts = jiffies; @@ -4151,6 +4142,50 @@ static void pwq_release_workfn(struct kt } } +/** + * pwq_adjust_max_active - update a pwq's max_active to the current setting + * @pwq: target pool_workqueue + * + * If @pwq isn't freezing, set @pwq->max_active to the associated + * workqueue's saved_max_active and activate inactive work items + * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. + */ +static void pwq_adjust_max_active(struct pool_workqueue *pwq) +{ + struct workqueue_struct *wq = pwq->wq; + bool freezable = wq->flags & WQ_FREEZABLE; + unsigned long flags; + + /* for @wq->saved_max_active */ + lockdep_assert_held(&wq->mutex); + + /* fast exit for non-freezable wqs */ + if (!freezable && pwq->max_active == wq->saved_max_active) + return; + + /* this function can be called during early boot w/ irq disabled */ + raw_spin_lock_irqsave(&pwq->pool->lock, flags); + + /* + * During [un]freezing, the caller is responsible for ensuring that + * this function is called at least once after @workqueue_freezing + * is updated and visible. + */ + if (!freezable || !workqueue_freezing) { + pwq->max_active = wq->saved_max_active; + + while (!list_empty(&pwq->inactive_works) && + pwq->nr_active < pwq->max_active) + pwq_activate_first_inactive(pwq); + + kick_pool(pwq->pool); + } else { + pwq->max_active = 0; + } + + raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); +} + /* initialize newly allocated @pwq which is associated with @wq and @pool */ static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, struct worker_pool *pool) @@ -4183,6 +4218,9 @@ static void link_pwq(struct pool_workque /* set the matching work_color */ pwq->work_color = wq->work_color; + /* sync max_active to the current setting */ + pwq_adjust_max_active(pwq); + /* link in @pwq */ list_add_rcu(&pwq->pwqs_node, &wq->pwqs); } @@ -4620,52 +4658,6 @@ static int init_rescuer(struct workqueue return 0; } -/** - * wq_adjust_max_active - update a wq's max_active to the current setting - * @wq: target workqueue - * - * If @wq isn't freezing, set @wq->max_active to the saved_max_active and - * activate inactive work items accordingly. If @wq is freezing, clear - * @wq->max_active to zero. - */ -static void wq_adjust_max_active(struct workqueue_struct *wq) -{ - struct pool_workqueue *pwq; - - lockdep_assert_held(&wq->mutex); - - if ((wq->flags & WQ_FREEZABLE) && workqueue_freezing) { - WRITE_ONCE(wq->max_active, 0); - return; - } - - if (wq->max_active == wq->saved_max_active) - return; - - /* - * Update @wq->max_active and then kick inactive work items if more - * active work items are allowed. This doesn't break work item ordering - * because new work items are always queued behind existing inactive - * work items if there are any. - */ - WRITE_ONCE(wq->max_active, wq->saved_max_active); - - for_each_pwq(pwq, wq) { - unsigned long flags; - - /* this function can be called during early boot w/ irq disabled */ - raw_spin_lock_irqsave(&pwq->pool->lock, flags); - - while (!list_empty(&pwq->inactive_works) && - pwq->nr_active < wq->max_active) - pwq_activate_first_inactive(pwq); - - kick_pool(pwq->pool); - - raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); - } -} - __printf(1, 4) struct workqueue_struct *alloc_workqueue(const char *fmt, unsigned int flags, @@ -4673,6 +4665,7 @@ struct workqueue_struct *alloc_workqueue { va_list args; struct workqueue_struct *wq; + struct pool_workqueue *pwq; int len; /* @@ -4711,7 +4704,6 @@ struct workqueue_struct *alloc_workqueue /* init wq */ wq->flags = flags; - wq->max_active = max_active; wq->saved_max_active = max_active; mutex_init(&wq->mutex); atomic_set(&wq->nr_pwqs_to_flush, 0); @@ -4740,7 +4732,8 @@ struct workqueue_struct *alloc_workqueue mutex_lock(&wq_pool_mutex); mutex_lock(&wq->mutex); - wq_adjust_max_active(wq); + for_each_pwq(pwq, wq) + pwq_adjust_max_active(pwq); mutex_unlock(&wq->mutex); list_add_tail_rcu(&wq->list, &workqueues); @@ -4878,6 +4871,8 @@ EXPORT_SYMBOL_GPL(destroy_workqueue); */ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) { + struct pool_workqueue *pwq; + /* disallow meddling with max_active for ordered workqueues */ if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) return; @@ -4888,7 +4883,9 @@ void workqueue_set_max_active(struct wor wq->flags &= ~__WQ_ORDERED; wq->saved_max_active = max_active; - wq_adjust_max_active(wq); + + for_each_pwq(pwq, wq) + pwq_adjust_max_active(pwq); mutex_unlock(&wq->mutex); } @@ -5135,8 +5132,8 @@ static void show_pwq(struct pool_workque pr_info(" pwq %d:", pool->id); pr_cont_pool_info(pool); - pr_cont(" active=%d refcnt=%d%s\n", - pwq->nr_active, pwq->refcnt, + pr_cont(" active=%d/%d refcnt=%d%s\n", + pwq->nr_active, pwq->max_active, pwq->refcnt, !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); hash_for_each(pool->busy_hash, bkt, worker, hentry) { @@ -5684,6 +5681,7 @@ EXPORT_SYMBOL_GPL(work_on_cpu_safe_key); void freeze_workqueues_begin(void) { struct workqueue_struct *wq; + struct pool_workqueue *pwq; mutex_lock(&wq_pool_mutex); @@ -5692,7 +5690,8 @@ void freeze_workqueues_begin(void) list_for_each_entry(wq, &workqueues, list) { mutex_lock(&wq->mutex); - wq_adjust_max_active(wq); + for_each_pwq(pwq, wq) + pwq_adjust_max_active(pwq); mutex_unlock(&wq->mutex); } @@ -5757,6 +5756,7 @@ out_unlock: void thaw_workqueues(void) { struct workqueue_struct *wq; + struct pool_workqueue *pwq; mutex_lock(&wq_pool_mutex); @@ -5768,7 +5768,8 @@ void thaw_workqueues(void) /* restore max_active and repopulate worklist */ list_for_each_entry(wq, &workqueues, list) { mutex_lock(&wq->mutex); - wq_adjust_max_active(wq); + for_each_pwq(pwq, wq) + pwq_adjust_max_active(pwq); mutex_unlock(&wq->mutex); }
