6.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman gregkh@linuxfoundation.org

This reverts commit fb89c8fa412f6caa34316c140e861bd3c4d7e83a which is commit 8318d6a6362f5903edb4c904a8dd447e59be4ad1 upstream

The workqueue patches backported to 6.8.y caused some reported regressions, so revert them for now.

Reported-by: Thorsten Leemhuis regressions@leemhuis.info Cc: Tejun Heo tj@kernel.org Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Nathan Chancellor nathan@kernel.org Cc: Sasha Levin sashal@kernel.org Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@leemhuis.in... Cc: Audra Mitchell audra@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/workqueue.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -7186,7 +7186,7 @@ void __init workqueue_init_early(void) WQ_FREEZABLE, 0); system_power_efficient_wq = alloc_workqueue("events_power_efficient", WQ_POWER_EFFICIENT, 0); - system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_pwr_efficient", + system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", WQ_FREEZABLE | WQ_POWER_EFFICIENT, 0); BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq ||

6.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman gregkh@linuxfoundation.org

This reverts commit 843288afd3cc6f3342659c6cf81fc47684d25563 which is commit 5797b1c18919cd9c289ded7954383e499f729ce0 upstream.

The workqueue patches backported to 6.8.y caused some reported regressions, so revert them for now.

Reported-by: Thorsten Leemhuis regressions@leemhuis.info Cc: Tejun Heo tj@kernel.org Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Nathan Chancellor nathan@kernel.org Cc: Sasha Levin sashal@kernel.org Cc: Audra Mitchell audra@redhat.com Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@leemhuis.in... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/workqueue.h | 35 ---- kernel/workqueue.c | 341 ++++------------------------------------------ 2 files changed, 35 insertions(+), 341 deletions(-)

--- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -391,13 +391,6 @@ enum { WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */ WQ_UNBOUND_MAX_ACTIVE = WQ_MAX_ACTIVE, WQ_DFL_ACTIVE = WQ_MAX_ACTIVE / 2, - - /* - * Per-node default cap on min_active. Unless explicitly set, min_active - * is set to min(max_active, WQ_DFL_MIN_ACTIVE). For more details, see - * workqueue_struct->min_active definition. - */ - WQ_DFL_MIN_ACTIVE = 8, };

/* @@ -440,33 +433,11 @@ extern struct workqueue_struct *system_f * alloc_workqueue - allocate a workqueue * @fmt: printf format for the name of the workqueue * @flags: WQ_* flags - * @max_active: max in-flight work items, 0 for default + * @max_active: max in-flight work items per CPU, 0 for default * remaining args: args for @fmt * - * For a per-cpu workqueue, @max_active limits the number of in-flight work - * items for each CPU. e.g. @max_active of 1 indicates that each CPU can be - * executing at most one work item for the workqueue. - * - * For unbound workqueues, @max_active limits the number of in-flight work items - * for the whole system. e.g. @max_active of 16 indicates that that there can be - * at most 16 work items executing for the workqueue in the whole system. - * - * As sharing the same active counter for an unbound workqueue across multiple - * NUMA nodes can be expensive, @max_active is distributed to each NUMA node - * according to the proportion of the number of online CPUs and enforced - * independently. - * - * Depending on online CPU distribution, a node may end up with per-node - * max_active which is significantly lower than @max_active, which can lead to - * deadlocks if the per-node concurrency limit is lower than the maximum number - * of interdependent work items for the workqueue. - * - * To guarantee forward progress regardless of online CPU distribution, the - * concurrency limit on every node is guaranteed to be equal to or greater than - * min_active which is set to min(@max_active, %WQ_DFL_MIN_ACTIVE). This means - * that the sum of per-node max_active's may be larger than @max_active. - * - * For detailed information on %WQ_* flags, please refer to + * Allocate a workqueue with the specified parameters. For detailed + * information on WQ_* flags, please refer to * Documentation/core-api/workqueue.rst. * * RETURNS: --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -122,9 +122,6 @@ enum { * * L: pool->lock protected. Access with pool->lock held. * - * LN: pool->lock and wq_node_nr_active->lock protected for writes. Either for - * reads. - * * K: Only modified by worker while holding pool->lock. Can be safely read by * self, while holding pool->lock or from IRQ context if %current is the * kworker. @@ -246,18 +243,17 @@ struct pool_workqueue { * pwq->inactive_works instead of pool->worklist and marked with * WORK_STRUCT_INACTIVE. * - * All work items marked with WORK_STRUCT_INACTIVE do not participate in - * nr_active and all work items in pwq->inactive_works are marked with - * WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE work items are - * in pwq->inactive_works. Some of them are ready to run in - * pool->worklist or worker->scheduled. Those work itmes are only struct - * wq_barrier which is used for flush_work() and should not participate - * in nr_active. For non-barrier work item, it is marked with - * WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. + * All work items marked with WORK_STRUCT_INACTIVE do not participate + * in pwq->nr_active and all work items in pwq->inactive_works are + * marked with WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE + * work items are in pwq->inactive_works. Some of them are ready to + * run in pool->worklist or worker->scheduled. Those work itmes are + * only struct wq_barrier which is used for flush_work() and should + * not participate in pwq->nr_active. For non-barrier work item, it + * is marked with WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. */ int nr_active; /* L: nr of active works */ struct list_head inactive_works; /* L: inactive works */ - struct list_head pending_node; /* LN: node on wq_node_nr_active->pending_pwqs */ struct list_head pwqs_node; /* WR: node on wq->pwqs */ struct list_head mayday_node; /* MD: node on wq->maydays */

@@ -289,19 +285,9 @@ struct wq_device; * on each CPU, in an unbound workqueue, max_active applies to the whole system. * As sharing a single nr_active across multiple sockets can be very expensive, * the counting and enforcement is per NUMA node. - * - * The following struct is used to enforce per-node max_active. When a pwq wants - * to start executing a work item, it should increment ->nr using - * tryinc_node_nr_active(). If acquisition fails due to ->nr already being over - * ->max, the pwq is queued on ->pending_pwqs. As in-flight work items finish - * and decrement ->nr, node_activate_pending_pwq() activates the pending pwqs in - * round-robin order. */ struct wq_node_nr_active { - int max; /* per-node max_active */ - atomic_t nr; /* per-node nr_active */ - raw_spinlock_t lock; /* nests inside pool locks */ - struct list_head pending_pwqs; /* LN: pwqs with inactive works */ + atomic_t nr; /* per-node nr_active count */ };

/* @@ -324,12 +310,8 @@ struct workqueue_struct { struct worker *rescuer; /* MD: rescue worker */

int nr_drainers; /* WQ: drain in progress */ - - /* See alloc_workqueue() function comment for info on min/max_active */ int max_active; /* WO: max active works */ - int min_active; /* WO: min active works */ int saved_max_active; /* WQ: saved max_active */ - int saved_min_active; /* WQ: saved min_active */

struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ struct pool_workqueue __rcu *dfl_pwq; /* PW: only for unbound wqs */ @@ -681,19 +663,6 @@ static struct pool_workqueue *unbound_pw lockdep_is_held(&wq->mutex)); }

-/** - * unbound_effective_cpumask - effective cpumask of an unbound workqueue - * @wq: workqueue of interest - * - * @wq->unbound_attrs->cpumask contains the cpumask requested by the user which - * is masked with wq_unbound_cpumask to determine the effective cpumask. The - * default pwq is always mapped to the pool with the current effective cpumask. - */ -static struct cpumask *unbound_effective_cpumask(struct workqueue_struct *wq) -{ - return unbound_pwq(wq, -1)->pool->attrs->__pod_cpumask; -} - static unsigned int work_color_to_flags(int color) { return color << WORK_STRUCT_COLOR_SHIFT; @@ -1489,46 +1458,6 @@ static struct wq_node_nr_active *wq_node }

/** - * wq_update_node_max_active - Update per-node max_actives to use - * @wq: workqueue to update - * @off_cpu: CPU that's going down, -1 if a CPU is not going down - * - * Update @wq->node_nr_active[]->max. @wq must be unbound. max_active is - * distributed among nodes according to the proportions of numbers of online - * cpus. The result is always between @wq->min_active and max_active. - */ -static void wq_update_node_max_active(struct workqueue_struct *wq, int off_cpu) -{ - struct cpumask *effective = unbound_effective_cpumask(wq); - int min_active = READ_ONCE(wq->min_active); - int max_active = READ_ONCE(wq->max_active); - int total_cpus, node; - - lockdep_assert_held(&wq->mutex); - - if (!cpumask_test_cpu(off_cpu, effective)) - off_cpu = -1; - - total_cpus = cpumask_weight_and(effective, cpu_online_mask); - if (off_cpu >= 0) - total_cpus--; - - for_each_node(node) { - int node_cpus; - - node_cpus = cpumask_weight_and(effective, cpumask_of_node(node)); - if (off_cpu >= 0 && cpu_to_node(off_cpu) == node) - node_cpus--; - - wq_node_nr_active(wq, node)->max = - clamp(DIV_ROUND_UP(max_active * node_cpus, total_cpus), - min_active, max_active); - } - - wq_node_nr_active(wq, NUMA_NO_NODE)->max = min_active; -} - -/** * get_pwq - get an extra reference on the specified pool_workqueue * @pwq: pool_workqueue to get * @@ -1625,98 +1554,35 @@ static bool pwq_activate_work(struct poo return true; }

-static bool tryinc_node_nr_active(struct wq_node_nr_active *nna) -{ - int max = READ_ONCE(nna->max); - - while (true) { - int old, tmp; - - old = atomic_read(&nna->nr); - if (old >= max) - return false; - tmp = atomic_cmpxchg_relaxed(&nna->nr, old, old + 1); - if (tmp == old) - return true; - } -} - /** * pwq_tryinc_nr_active - Try to increment nr_active for a pwq * @pwq: pool_workqueue of interest - * @fill: max_active may have increased, try to increase concurrency level * * Try to increment nr_active for @pwq. Returns %true if an nr_active count is * successfully obtained. %false otherwise. */ -static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq, bool fill) +static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq) { struct workqueue_struct *wq = pwq->wq; struct worker_pool *pool = pwq->pool; struct wq_node_nr_active *nna = wq_node_nr_active(wq, pool->node); - bool obtained = false; + bool obtained;

lockdep_assert_held(&pool->lock);

- if (!nna) { - /* per-cpu workqueue, pwq->nr_active is sufficient */ - obtained = pwq->nr_active < READ_ONCE(wq->max_active); - goto out; - } - - /* - * Unbound workqueue uses per-node shared nr_active $nna. If @pwq is - * already waiting on $nna, pwq_dec_nr_active() will maintain the - * concurrency level. Don't jump the line. - * - * We need to ignore the pending test after max_active has increased as - * pwq_dec_nr_active() can only maintain the concurrency level but not - * increase it. This is indicated by @fill. - */ - if (!list_empty(&pwq->pending_node) && likely(!fill)) - goto out; - - obtained = tryinc_node_nr_active(nna); - if (obtained) - goto out; - - /* - * Lockless acquisition failed. Lock, add ourself to $nna->pending_pwqs - * and try again. The smp_mb() is paired with the implied memory barrier - * of atomic_dec_return() in pwq_dec_nr_active() to ensure that either - * we see the decremented $nna->nr or they see non-empty - * $nna->pending_pwqs. - */ - raw_spin_lock(&nna->lock); - - if (list_empty(&pwq->pending_node)) - list_add_tail(&pwq->pending_node, &nna->pending_pwqs); - else if (likely(!fill)) - goto out_unlock; - - smp_mb(); - - obtained = tryinc_node_nr_active(nna); - - /* - * If @fill, @pwq might have already been pending. Being spuriously - * pending in cold paths doesn't affect anything. Let's leave it be. - */ - if (obtained && likely(!fill)) - list_del_init(&pwq->pending_node); + obtained = pwq->nr_active < READ_ONCE(wq->max_active);

-out_unlock: - raw_spin_unlock(&nna->lock); -out: - if (obtained) + if (obtained) { pwq->nr_active++; + if (nna) + atomic_inc(&nna->nr); + } return obtained; }

/** * pwq_activate_first_inactive - Activate the first inactive work item on a pwq * @pwq: pool_workqueue of interest - * @fill: max_active may have increased, try to increase concurrency level * * Activate the first inactive work item of @pwq if available and allowed by * max_active limit. @@ -1724,13 +1590,13 @@ out: * Returns %true if an inactive work item has been activated. %false if no * inactive work item is found or max_active limit is reached. */ -static bool pwq_activate_first_inactive(struct pool_workqueue *pwq, bool fill) +static bool pwq_activate_first_inactive(struct pool_workqueue *pwq) { struct work_struct *work = list_first_entry_or_null(&pwq->inactive_works, struct work_struct, entry);

- if (work && pwq_tryinc_nr_active(pwq, fill)) { + if (work && pwq_tryinc_nr_active(pwq)) { __pwq_activate_work(pwq, work); return true; } else { @@ -1739,92 +1605,10 @@ static bool pwq_activate_first_inactive( }

/** - * node_activate_pending_pwq - Activate a pending pwq on a wq_node_nr_active - * @nna: wq_node_nr_active to activate a pending pwq for - * @caller_pool: worker_pool the caller is locking - * - * Activate a pwq in @nna->pending_pwqs. Called with @caller_pool locked. - * @caller_pool may be unlocked and relocked to lock other worker_pools. - */ -static void node_activate_pending_pwq(struct wq_node_nr_active *nna, - struct worker_pool *caller_pool) -{ - struct worker_pool *locked_pool = caller_pool; - struct pool_workqueue *pwq; - struct work_struct *work; - - lockdep_assert_held(&caller_pool->lock); - - raw_spin_lock(&nna->lock); -retry: - pwq = list_first_entry_or_null(&nna->pending_pwqs, - struct pool_workqueue, pending_node); - if (!pwq) - goto out_unlock; - - /* - * If @pwq is for a different pool than @locked_pool, we need to lock - * @pwq->pool->lock. Let's trylock first. If unsuccessful, do the unlock - * / lock dance. For that, we also need to release @nna->lock as it's - * nested inside pool locks. - */ - if (pwq->pool != locked_pool) { - raw_spin_unlock(&locked_pool->lock); - locked_pool = pwq->pool; - if (!raw_spin_trylock(&locked_pool->lock)) { - raw_spin_unlock(&nna->lock); - raw_spin_lock(&locked_pool->lock); - raw_spin_lock(&nna->lock); - goto retry; - } - } - - /* - * $pwq may not have any inactive work items due to e.g. cancellations. - * Drop it from pending_pwqs and see if there's another one. - */ - work = list_first_entry_or_null(&pwq->inactive_works, - struct work_struct, entry); - if (!work) { - list_del_init(&pwq->pending_node); - goto retry; - } - - /* - * Acquire an nr_active count and activate the inactive work item. If - * $pwq still has inactive work items, rotate it to the end of the - * pending_pwqs so that we round-robin through them. This means that - * inactive work items are not activated in queueing order which is fine - * given that there has never been any ordering across different pwqs. - */ - if (likely(tryinc_node_nr_active(nna))) { - pwq->nr_active++; - __pwq_activate_work(pwq, work); - - if (list_empty(&pwq->inactive_works)) - list_del_init(&pwq->pending_node); - else - list_move_tail(&pwq->pending_node, &nna->pending_pwqs); - - /* if activating a foreign pool, make sure it's running */ - if (pwq->pool != caller_pool) - kick_pool(pwq->pool); - } - -out_unlock: - raw_spin_unlock(&nna->lock); - if (locked_pool != caller_pool) { - raw_spin_unlock(&locked_pool->lock); - raw_spin_lock(&caller_pool->lock); - } -} - -/** * pwq_dec_nr_active - Retire an active count * @pwq: pool_workqueue of interest * * Decrement @pwq's nr_active and try to activate the first inactive work item. - * For unbound workqueues, this function may temporarily drop @pwq->pool->lock. */ static void pwq_dec_nr_active(struct pool_workqueue *pwq) { @@ -1844,29 +1628,12 @@ static void pwq_dec_nr_active(struct poo * inactive work item on @pwq itself. */ if (!nna) { - pwq_activate_first_inactive(pwq, false); + pwq_activate_first_inactive(pwq); return; }

- /* - * If @pwq is for an unbound workqueue, it's more complicated because - * multiple pwqs and pools may be sharing the nr_active count. When a - * pwq needs to wait for an nr_active count, it puts itself on - * $nna->pending_pwqs. The following atomic_dec_return()'s implied - * memory barrier is paired with smp_mb() in pwq_tryinc_nr_active() to - * guarantee that either we see non-empty pending_pwqs or they see - * decremented $nna->nr. - * - * $nna->max may change as CPUs come online/offline and @pwq->wq's - * max_active gets updated. However, it is guaranteed to be equal to or - * larger than @pwq->wq->min_active which is above zero unless freezing. - * This maintains the forward progress guarantee. - */ - if (atomic_dec_return(&nna->nr) >= READ_ONCE(nna->max)) - return; - - if (!list_empty(&nna->pending_pwqs)) - node_activate_pending_pwq(nna, pool); + atomic_dec(&nna->nr); + pwq_activate_first_inactive(pwq); }

/** @@ -2187,7 +1954,7 @@ retry: * @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_tryinc_nr_active(pwq, false)) { + if (list_empty(&pwq->inactive_works) && pwq_tryinc_nr_active(pwq)) { if (list_empty(&pool->worklist)) pool->watchdog_ts = jiffies;

@@ -3420,7 +3187,7 @@ static void insert_wq_barrier(struct poo

barr->task = current;

- /* The barrier work item does not participate in nr_active. */ + /* The barrier work item does not participate in pwq->nr_active. */ work_flags |= WORK_STRUCT_INACTIVE;

/* @@ -4336,8 +4103,6 @@ static void free_node_nr_active(struct w static void init_node_nr_active(struct wq_node_nr_active *nna) { atomic_set(&nna->nr, 0); - raw_spin_lock_init(&nna->lock); - INIT_LIST_HEAD(&nna->pending_pwqs); }

/* @@ -4577,15 +4342,6 @@ static void pwq_release_workfn(struct kt mutex_unlock(&wq_pool_mutex); }

- if (!list_empty(&pwq->pending_node)) { - struct wq_node_nr_active *nna = - wq_node_nr_active(pwq->wq, pwq->pool->node); - - raw_spin_lock_irq(&nna->lock); - list_del_init(&pwq->pending_node); - raw_spin_unlock_irq(&nna->lock); - } - call_rcu(&pwq->rcu, rcu_free_pwq);

/* @@ -4611,7 +4367,6 @@ static void init_pwq(struct pool_workque pwq->flush_color = -1; pwq->refcnt = 1; INIT_LIST_HEAD(&pwq->inactive_works); - INIT_LIST_HEAD(&pwq->pending_node); INIT_LIST_HEAD(&pwq->pwqs_node); INIT_LIST_HEAD(&pwq->mayday_node); kthread_init_work(&pwq->release_work, pwq_release_workfn); @@ -4819,9 +4574,6 @@ static void apply_wqattrs_commit(struct ctx->pwq_tbl[cpu]); ctx->dfl_pwq = install_unbound_pwq(ctx->wq, -1, ctx->dfl_pwq);

- /* update node_nr_active->max */ - wq_update_node_max_active(ctx->wq, -1); - mutex_unlock(&ctx->wq->mutex); }

@@ -5082,35 +4834,24 @@ static int init_rescuer(struct workqueue static void wq_adjust_max_active(struct workqueue_struct *wq) { bool activated; - int new_max, new_min;

lockdep_assert_held(&wq->mutex);

if ((wq->flags & WQ_FREEZABLE) && workqueue_freezing) { - new_max = 0; - new_min = 0; - } else { - new_max = wq->saved_max_active; - new_min = wq->saved_min_active; + WRITE_ONCE(wq->max_active, 0); + return; }

- if (wq->max_active == new_max && wq->min_active == new_min) + if (wq->max_active == wq->saved_max_active) return;

/* - * Update @wq->max/min_active and then kick inactive work items if more + * 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, new_max); - WRITE_ONCE(wq->min_active, new_min); - - if (wq->flags & WQ_UNBOUND) - wq_update_node_max_active(wq, -1); - - if (new_max == 0) - return; + WRITE_ONCE(wq->max_active, wq->saved_max_active);

/* * Round-robin through pwq's activating the first inactive work item @@ -5125,7 +4866,7 @@ static void wq_adjust_max_active(struct

/* can be called during early boot w/ irq disabled */ raw_spin_lock_irqsave(&pwq->pool->lock, flags); - if (pwq_activate_first_inactive(pwq, true)) { + if (pwq_activate_first_inactive(pwq)) { activated = true; kick_pool(pwq->pool); } @@ -5187,9 +4928,7 @@ struct workqueue_struct *alloc_workqueue /* init wq */ wq->flags = flags; wq->max_active = max_active; - wq->min_active = min(max_active, WQ_DFL_MIN_ACTIVE); - wq->saved_max_active = wq->max_active; - wq->saved_min_active = wq->min_active; + wq->saved_max_active = max_active; mutex_init(&wq->mutex); atomic_set(&wq->nr_pwqs_to_flush, 0); INIT_LIST_HEAD(&wq->pwqs); @@ -5355,8 +5094,7 @@ EXPORT_SYMBOL_GPL(destroy_workqueue); * @wq: target workqueue * @max_active: new max_active value. * - * Set max_active of @wq to @max_active. See the alloc_workqueue() function - * comment. + * Set max_active of @wq to @max_active. * * CONTEXT: * Don't call from IRQ context. @@ -5373,9 +5111,6 @@ void workqueue_set_max_active(struct wor

wq->flags &= ~__WQ_ORDERED; wq->saved_max_active = max_active; - if (wq->flags & WQ_UNBOUND) - wq->saved_min_active = min(wq->saved_min_active, max_active); - wq_adjust_max_active(wq);

mutex_unlock(&wq->mutex); @@ -6057,10 +5792,6 @@ int workqueue_online_cpu(unsigned int cp

for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) wq_update_pod(wq, tcpu, cpu, true); - - mutex_lock(&wq->mutex); - wq_update_node_max_active(wq, -1); - mutex_unlock(&wq->mutex); } }

@@ -6089,10 +5820,6 @@ int workqueue_offline_cpu(unsigned int c

for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) wq_update_pod(wq, tcpu, cpu, false); - - mutex_lock(&wq->mutex); - wq_update_node_max_active(wq, cpu); - mutex_unlock(&wq->mutex); } } mutex_unlock(&wq_pool_mutex); @@ -7373,12 +7100,8 @@ void __init workqueue_init_topology(void * combinations to apply per-pod sharing. */ list_for_each_entry(wq, &workqueues, list) { - for_each_online_cpu(cpu) + for_each_online_cpu(cpu) { wq_update_pod(wq, cpu, cpu, true); - if (wq->flags & WQ_UNBOUND) { - mutex_lock(&wq->mutex); - wq_update_node_max_active(wq, -1); - mutex_unlock(&wq->mutex); } }

6.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman gregkh@linuxfoundation.org

This reverts commit 3fb5dbc8bb3759ad0a82d6bf5ed32866c0410a79 which is commit 9f66cff212bb3c1cd25996aaa0dfd0c9e9d8baab upstream.

The workqueue patches backported to 6.8.y caused some reported regressions, so revert them for now.

Reported-by: Thorsten Leemhuis regressions@leemhuis.info Cc: Tejun Heo tj@kernel.org Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Nathan Chancellor nathan@kernel.org Cc: Sasha Levin sashal@kernel.org Cc: Audra Mitchell audra@redhat.com Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@leemhuis.in... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/workqueue.c | 64 +++++++++++++++++++---------------------------------- 1 file changed, 24 insertions(+), 40 deletions(-)

--- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -304,7 +304,7 @@ struct workqueue_struct { int saved_max_active; /* WQ: saved max_active */

struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ - struct pool_workqueue __rcu *dfl_pwq; /* PW: only for unbound wqs */ + struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */

#ifdef CONFIG_SYSFS struct wq_device *wq_dev; /* I: for sysfs interface */ @@ -635,23 +635,6 @@ static int worker_pool_assign_id(struct return ret; }

-static struct pool_workqueue __rcu ** -unbound_pwq_slot(struct workqueue_struct *wq, int cpu) -{ - if (cpu >= 0) - return per_cpu_ptr(wq->cpu_pwq, cpu); - else - return &wq->dfl_pwq; -} - -/* @cpu < 0 for dfl_pwq */ -static struct pool_workqueue *unbound_pwq(struct workqueue_struct *wq, int cpu) -{ - return rcu_dereference_check(*unbound_pwq_slot(wq, cpu), - lockdep_is_held(&wq_pool_mutex) || - lockdep_is_held(&wq->mutex)); -} - static unsigned int work_color_to_flags(int color) { return color << WORK_STRUCT_COLOR_SHIFT; @@ -4341,11 +4324,10 @@ static void wq_calc_pod_cpumask(struct w "possible intersect\n"); }

-/* install @pwq into @wq and return the old pwq, @cpu < 0 for dfl_pwq */ +/* install @pwq into @wq's cpu_pwq and return the old pwq */ static struct pool_workqueue *install_unbound_pwq(struct workqueue_struct *wq, int cpu, struct pool_workqueue *pwq) { - struct pool_workqueue __rcu **slot = unbound_pwq_slot(wq, cpu); struct pool_workqueue *old_pwq;

lockdep_assert_held(&wq_pool_mutex); @@ -4354,8 +4336,8 @@ static struct pool_workqueue *install_un /* link_pwq() can handle duplicate calls */ link_pwq(pwq);

- old_pwq = rcu_access_pointer(*slot); - rcu_assign_pointer(*slot, pwq); + old_pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu)); + rcu_assign_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu), pwq); return old_pwq; }

@@ -4455,11 +4437,14 @@ static void apply_wqattrs_commit(struct

copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs);

- /* save the previous pwqs and install the new ones */ + /* save the previous pwq and install the new one */ for_each_possible_cpu(cpu) ctx->pwq_tbl[cpu] = install_unbound_pwq(ctx->wq, cpu, ctx->pwq_tbl[cpu]); - ctx->dfl_pwq = install_unbound_pwq(ctx->wq, -1, ctx->dfl_pwq); + + /* @dfl_pwq might not have been used, ensure it's linked */ + link_pwq(ctx->dfl_pwq); + swap(ctx->wq->dfl_pwq, ctx->dfl_pwq);

mutex_unlock(&ctx->wq->mutex); } @@ -4569,7 +4554,9 @@ static void wq_update_pod(struct workque

/* nothing to do if the target cpumask matches the current pwq */ wq_calc_pod_cpumask(target_attrs, cpu, off_cpu); - if (wqattrs_equal(target_attrs, unbound_pwq(wq, cpu)->pool->attrs)) + pwq = rcu_dereference_protected(*per_cpu_ptr(wq->cpu_pwq, cpu), + lockdep_is_held(&wq_pool_mutex)); + if (wqattrs_equal(target_attrs, pwq->pool->attrs)) return;

/* create a new pwq */ @@ -4587,11 +4574,10 @@ static void wq_update_pod(struct workque

use_dfl_pwq: mutex_lock(&wq->mutex); - pwq = unbound_pwq(wq, -1); - raw_spin_lock_irq(&pwq->pool->lock); - get_pwq(pwq); - raw_spin_unlock_irq(&pwq->pool->lock); - old_pwq = install_unbound_pwq(wq, cpu, pwq); + raw_spin_lock_irq(&wq->dfl_pwq->pool->lock); + get_pwq(wq->dfl_pwq); + raw_spin_unlock_irq(&wq->dfl_pwq->pool->lock); + old_pwq = install_unbound_pwq(wq, cpu, wq->dfl_pwq); out_unlock: mutex_unlock(&wq->mutex); put_pwq_unlocked(old_pwq); @@ -4629,13 +4615,10 @@ static int alloc_and_link_pwqs(struct wo

cpus_read_lock(); if (wq->flags & __WQ_ORDERED) { - struct pool_workqueue *dfl_pwq; - ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); /* there should only be single pwq for ordering guarantee */ - dfl_pwq = rcu_access_pointer(wq->dfl_pwq); - WARN(!ret && (wq->pwqs.next != &dfl_pwq->pwqs_node || - wq->pwqs.prev != &dfl_pwq->pwqs_node), + WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || + wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), "ordering guarantee broken for workqueue %s\n", wq->name); } else { ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); @@ -4866,7 +4849,7 @@ static bool pwq_busy(struct pool_workque if (pwq->nr_in_flight[i]) return true;

- if ((pwq != rcu_access_pointer(pwq->wq->dfl_pwq)) && (pwq->refcnt > 1)) + if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1)) return true; if (!pwq_is_empty(pwq)) return true; @@ -4950,12 +4933,13 @@ void destroy_workqueue(struct workqueue_ rcu_read_lock();

for_each_possible_cpu(cpu) { - put_pwq_unlocked(unbound_pwq(wq, cpu)); - RCU_INIT_POINTER(*unbound_pwq_slot(wq, cpu), NULL); + pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu)); + RCU_INIT_POINTER(*per_cpu_ptr(wq->cpu_pwq, cpu), NULL); + put_pwq_unlocked(pwq); }

- put_pwq_unlocked(unbound_pwq(wq, -1)); - RCU_INIT_POINTER(*unbound_pwq_slot(wq, -1), NULL); + put_pwq_unlocked(wq->dfl_pwq); + wq->dfl_pwq = NULL;

rcu_read_unlock(); }

6.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman gregkh@linuxfoundation.org

This reverts commit 6584970ff38fc8f875c683dbb47bb38d4132a528 which is commit 1c270b79ce0b8290f146255ea9057243f6dd3c17 upstream.

The workqueue patches backported to 6.8.y caused some reported regressions, so revert them for now.

Reported-by: Thorsten Leemhuis regressions@leemhuis.info Cc: Tejun Heo tj@kernel.org Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Nathan Chancellor nathan@kernel.org Cc: Sasha Levin sashal@kernel.org Cc: Audra Mitchell audra@redhat.com Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@leemhuis.in... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/workqueue.c | 86 +++++++++++------------------------------------------ 1 file changed, 19 insertions(+), 67 deletions(-)

--- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1464,14 +1464,11 @@ static bool pwq_is_empty(struct pool_wor static void __pwq_activate_work(struct pool_workqueue *pwq, struct work_struct *work) { - unsigned long *wdb = work_data_bits(work); - - WARN_ON_ONCE(!(*wdb & WORK_STRUCT_INACTIVE)); trace_workqueue_activate_work(work); if (list_empty(&pwq->pool->worklist)) pwq->pool->watchdog_ts = jiffies; move_linked_works(work, &pwq->pool->worklist, NULL); - __clear_bit(WORK_STRUCT_INACTIVE_BIT, wdb); + __clear_bit(WORK_STRUCT_INACTIVE_BIT, work_data_bits(work)); }

/** @@ -1496,66 +1493,12 @@ static bool pwq_activate_work(struct poo return true; }

-/** - * pwq_tryinc_nr_active - Try to increment nr_active for a pwq - * @pwq: pool_workqueue of interest - * - * Try to increment nr_active for @pwq. Returns %true if an nr_active count is - * successfully obtained. %false otherwise. - */ -static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq) -{ - struct workqueue_struct *wq = pwq->wq; - struct worker_pool *pool = pwq->pool; - bool obtained; - - lockdep_assert_held(&pool->lock); - - obtained = pwq->nr_active < READ_ONCE(wq->max_active); - - if (obtained) - pwq->nr_active++; - return obtained; -} - -/** - * pwq_activate_first_inactive - Activate the first inactive work item on a pwq - * @pwq: pool_workqueue of interest - * - * Activate the first inactive work item of @pwq if available and allowed by - * max_active limit. - * - * Returns %true if an inactive work item has been activated. %false if no - * inactive work item is found or max_active limit is reached. - */ -static bool pwq_activate_first_inactive(struct pool_workqueue *pwq) -{ - struct work_struct *work = - list_first_entry_or_null(&pwq->inactive_works, - struct work_struct, entry); - - if (work && pwq_tryinc_nr_active(pwq)) { - __pwq_activate_work(pwq, work); - return true; - } else { - return false; - } -} - -/** - * pwq_dec_nr_active - Retire an active count - * @pwq: pool_workqueue of interest - * - * Decrement @pwq's nr_active and try to activate the first inactive work item. - */ -static void pwq_dec_nr_active(struct pool_workqueue *pwq) +static void pwq_activate_first_inactive(struct pool_workqueue *pwq) { - struct worker_pool *pool = pwq->pool; + struct work_struct *work = list_first_entry(&pwq->inactive_works, + struct work_struct, entry);

- lockdep_assert_held(&pool->lock); - - pwq->nr_active--; - pwq_activate_first_inactive(pwq); + pwq_activate_work(pwq, work); }

/** @@ -1573,8 +1516,14 @@ static void pwq_dec_nr_in_flight(struct { int color = get_work_color(work_data);

- if (!(work_data & WORK_STRUCT_INACTIVE)) - pwq_dec_nr_active(pwq); + if (!(work_data & WORK_STRUCT_INACTIVE)) { + 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)) + pwq_activate_first_inactive(pwq); + } + }

pwq->nr_in_flight[color]--;

@@ -1876,11 +1825,13 @@ retry: * @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_tryinc_nr_active(pwq)) { + if (list_empty(&pwq->inactive_works) && + pwq->nr_active < READ_ONCE(pwq->wq->max_active)) { if (list_empty(&pool->worklist)) pool->watchdog_ts = jiffies;

trace_workqueue_activate_work(work); + pwq->nr_active++; insert_work(pwq, work, &pool->worklist, work_flags); kick_pool(pool); } else { @@ -4729,8 +4680,9 @@ static void wq_adjust_max_active(struct /* this function can be called during early boot w/ irq disabled */ raw_spin_lock_irqsave(&pwq->pool->lock, flags);

- while (pwq_activate_first_inactive(pwq)) - ; + while (!list_empty(&pwq->inactive_works) && + pwq->nr_active < wq->max_active) + pwq_activate_first_inactive(pwq);

kick_pool(pwq->pool);

6.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman gregkh@linuxfoundation.org

This reverts commit 70abdc2f6c906ffea699f6e0e08fcbd9437e6bcc which is commit afa87ce85379e2d93863fce595afdb5771a84004 upstream.

The workqueue patches backported to 6.8.y caused some reported regressions, so revert them for now.

Reported-by: Thorsten Leemhuis regressions@leemhuis.info Cc: Tejun Heo tj@kernel.org Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Nathan Chancellor nathan@kernel.org Cc: Sasha Levin sashal@kernel.org Cc: Audra Mitchell audra@redhat.com Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@leemhuis.in... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/workqueue.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-)

--- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1456,11 +1456,6 @@ static void put_pwq_unlocked(struct pool } }

-static bool pwq_is_empty(struct pool_workqueue *pwq) -{ - return !pwq->nr_active && list_empty(&pwq->inactive_works); -} - static void pwq_activate_inactive_work(struct work_struct *work) { struct pool_workqueue *pwq = get_work_pwq(work); @@ -3330,7 +3325,7 @@ reflush: bool drained;

raw_spin_lock_irq(&pwq->pool->lock); - drained = pwq_is_empty(pwq); + drained = !pwq->nr_active && list_empty(&pwq->inactive_works); raw_spin_unlock_irq(&pwq->pool->lock);

if (drained) @@ -4777,7 +4772,7 @@ static bool pwq_busy(struct pool_workque

if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1)) return true; - if (!pwq_is_empty(pwq)) + if (pwq->nr_active || !list_empty(&pwq->inactive_works)) return true;

return false; @@ -5215,7 +5210,7 @@ void show_one_workqueue(struct workqueue unsigned long flags;

for_each_pwq(pwq, wq) { - if (!pwq_is_empty(pwq)) { + if (pwq->nr_active || !list_empty(&pwq->inactive_works)) { idle = false; break; } @@ -5227,7 +5222,7 @@ void show_one_workqueue(struct workqueue

for_each_pwq(pwq, wq) { raw_spin_lock_irqsave(&pwq->pool->lock, flags); - if (!pwq_is_empty(pwq)) { + if (pwq->nr_active || !list_empty(&pwq->inactive_works)) { /* * Defer printing to avoid deadlocks in console * drivers that queue work while holding locks

6.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman gregkh@linuxfoundation.org

This reverts commit 43f0cec175f92c7a01e43d5d6f276262670a97ed which is commit 31c89007285d365aa36f71d8fb0701581c770a27 upstream.

The workqueue patches backported to 6.8.y caused some reported regressions, so revert them for now.

Reported-by: Thorsten Leemhuis regressions@leemhuis.info Cc: Tejun Heo tj@kernel.org Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Nathan Chancellor nathan@kernel.org Cc: Sasha Levin sashal@kernel.org Cc: Audra Mitchell audra@redhat.com Link: https://lore.kernel.org/all/ce4c2f67-c298-48a0-87a3-f933d646c73b@leemhuis.in... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/workqueue.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)

--- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -108,7 +108,7 @@ enum { RESCUER_NICE_LEVEL = MIN_NICE, HIGHPRI_NICE_LEVEL = MIN_NICE,

- WQ_NAME_LEN = 32, + WQ_NAME_LEN = 24, };

/* @@ -4666,7 +4666,6 @@ struct workqueue_struct *alloc_workqueue va_list args; struct workqueue_struct *wq; struct pool_workqueue *pwq; - int len;

/* * Unbound && max_active == 1 used to imply ordered, which is no longer @@ -4693,12 +4692,9 @@ struct workqueue_struct *alloc_workqueue }

va_start(args, max_active); - len = vsnprintf(wq->name, sizeof(wq->name), fmt, args); + vsnprintf(wq->name, sizeof(wq->name), fmt, args); va_end(args);

- if (len >= WQ_NAME_LEN) - pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n", wq->name); - max_active = max_active ?: WQ_DFL_ACTIVE; max_active = wq_clamp_max_active(max_active, flags, wq->name);