[PATCH v3] module: replace use of system_wq with system_dfl_wq

Marco Crivellari
2025-11-11T09:51:01Z

Currently if a user enqueues a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistency cannot be addressed without refactoring the API.

This continues the effort to refactor workqueue APIs, which began with
the introduction of new workqueues and a new alloc_workqueue flag in:

commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

Switch to using system_dfl_wq, the new unbound workqueue, because the
users do not benefit from a per-cpu workqueue.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
---
Changes in v3:
- rebased on 6.18-rc5
- commit log improved

Changes in v2:
- a per-cpu wq is not needed: replace system_wq with system_dfl_wq
---
kernel/module/dups.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/module/dups.c b/kernel/module/dups.c
index bd2149fbe117..0b633f2edda6 100644
--- a/kernel/module/dups.c
+++ b/kernel/module/dups.c
@@ -113,7 +113,7 @@ static void kmod_dup_request_complete(struct work_struct *work)
* let this linger forever as this is just a boot optimization for
* possible abuses of vmalloc() incurred by finit_module() thrashing.
*/
- queue_delayed_work(system_wq, &kmod_req->delete_work, 60 * HZ);
+ queue_delayed_work(system_dfl_wq, &kmod_req->delete_work, 60 * HZ);
}

bool kmod_dup_request_exists_wait(char *module_name, bool wait, int *dup_ret)
@@ -240,7 +240,7 @@ void kmod_dup_request_announce(char *module_name, int ret)
* There is no rush. But we also don't want to hold the
* caller up forever or introduce any boot delays.
*/
- queue_work(system_wq, &kmod_req->complete_work);
+ queue_work(system_dfl_wq, &kmod_req->complete_work);

out:
mutex_unlock(&kmod_dup_mutex);
--
2.51.1