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Message-ID: <20250905090130.101724-2-marco.crivellari@suse.com>
Date: Fri, 5 Sep 2025 11:01:30 +0200
From: Marco Crivellari <marco.crivellari@...e.com>
To: linux-kernel@...r.kernel.org,
linux-modules@...r.kernel.org
Cc: Tejun Heo <tj@...nel.org>,
Lai Jiangshan <jiangshanlai@...il.com>,
Frederic Weisbecker <frederic@...nel.org>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Marco Crivellari <marco.crivellari@...e.com>,
Michal Hocko <mhocko@...e.com>,
Luis Chamberlain <mcgrof@...nel.org>,
Petr Pavlu <petr.pavlu@...e.com>
Subject: [PATCH 1/1] module: replace use of system_wq with system_percpu_wq
Currently if a user enqueue 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 consistentcy cannot be addressed without refactoring the API.
system_wq is a per-CPU worqueue, yet nothing in its name tells about that
CPU affinity constraint, which is very often not required by users. Make
it clear by adding a system_percpu_wq.
queue_work() / queue_delayed_work() mod_delayed_work() will now use the
new per-cpu wq: whether the user still stick on the old name a warn will
be printed along a wq redirect to the new one.
This patch add the new system_percpu_wq except for mm, fs and net
subsystem, whom are handled in separated patches.
The old wq will be kept for a few release cylces.
Suggested-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@...e.com>
---
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..e72fa393a2ec 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_percpu_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_percpu_wq, &kmod_req->complete_work);
out:
mutex_unlock(&kmod_dup_mutex);
--
2.51.0
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