From bf52b1ac6ab41a060511d56d0f2da12f3a2486db Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 8 Feb 2024 14:14:16 -1000 Subject: [PATCH] async: Use a dedicated unbound workqueue with raised min_active Async can schedule a number of interdependent work items. However, since 5797b1c18919 ("workqueue: Implement system-wide nr_active enforcement for unbound workqueues"), unbound workqueues have separate min_active which sets the number of interdependent work items that can be handled. This default value is 8 which isn't sufficient for async and can lead to stalls during resume from suspend in some cases. Let's use a dedicated unbound workqueue with raised min_active. Link: http://lkml.kernel.org/r/708a65cc-79ec-44a6-8454-a93d0f3114c3@samsung.com Reported-by: Marek Szyprowski Cc: Rafael J. Wysocki Tested-by: Marek Szyprowski Signed-off-by: Tejun Heo --- include/linux/async.h | 1 + init/main.c | 1 + kernel/async.c | 17 ++++++++++++++++- 3 files changed, 18 insertions(+), 1 deletion(-) diff --git a/include/linux/async.h b/include/linux/async.h index 33c9ff4afb49..19b778d08600 100644 --- a/include/linux/async.h +++ b/include/linux/async.h @@ -120,4 +120,5 @@ extern void async_synchronize_cookie(async_cookie_t cookie); extern void async_synchronize_cookie_domain(async_cookie_t cookie, struct async_domain *domain); extern bool current_is_async(void); +extern void async_init(void); #endif diff --git a/init/main.c b/init/main.c index e24b0780fdff..685db36c999f 100644 --- a/init/main.c +++ b/init/main.c @@ -1545,6 +1545,7 @@ static noinline void __init kernel_init_freeable(void) sched_init_smp(); workqueue_init_topology(); + async_init(); padata_init(); page_alloc_init_late(); diff --git a/kernel/async.c b/kernel/async.c index 97f224a5257b..4c3e6a44595f 100644 --- a/kernel/async.c +++ b/kernel/async.c @@ -64,6 +64,7 @@ static async_cookie_t next_cookie = 1; static LIST_HEAD(async_global_pending); /* pending from all registered doms */ static ASYNC_DOMAIN(async_dfl_domain); static DEFINE_SPINLOCK(async_lock); +static struct workqueue_struct *async_wq; struct async_entry { struct list_head domain_list; @@ -174,7 +175,7 @@ static async_cookie_t __async_schedule_node_domain(async_func_t func, spin_unlock_irqrestore(&async_lock, flags); /* schedule for execution */ - queue_work_node(node, system_unbound_wq, &entry->work); + queue_work_node(node, async_wq, &entry->work); return newcookie; } @@ -345,3 +346,17 @@ bool current_is_async(void) return worker && worker->current_func == async_run_entry_fn; } EXPORT_SYMBOL_GPL(current_is_async); + +void __init async_init(void) +{ + /* + * Async can schedule a number of interdependent work items. However, + * unbound workqueues can handle only upto min_active interdependent + * work items. The default min_active of 8 isn't sufficient for async + * and can lead to stalls. Let's use a dedicated workqueue with raised + * min_active. + */ + async_wq = alloc_workqueue("async", WQ_UNBOUND, 0); + BUG_ON(!async_wq); + workqueue_set_min_active(async_wq, WQ_DFL_ACTIVE); +}