From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Tejun Heo <tj@kernel.org>, Petr Mladek <pmladek@suse.com>,
Michal Hocko <mhocko@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Wedson Almeida Filho <wedsonaf@google.com>,
Lai Jiangshan <jiangshanlai@gmail.com>
Subject: [RFC PATCH 3/8] workqueue: Set PF_NO_SETAFFINITY instead of kthread_bind_mask()
Date: Thu, 4 Aug 2022 16:41:30 +0800 [thread overview]
Message-ID: <20220804084135.92425-4-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20220804084135.92425-1-jiangshanlai@gmail.com>
From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
kthread_bind_mask() can't work correctly if spurious wakeup
happens before kthread_bind_mask().
And a spuriously wakeup worker's cpumask can be possibly changed
by a userspace if worker_attach_to_pool() is called earlier than
kthread_bind_mask().
To avoid the problem caused by spurious wokeup, set PF_NO_SETAFFINITY
at the starting of workers where kthread_bind_mask() can't be used
and luckily workqueue code binds cpumask by itself, all it needs is
only PF_NO_SETAFFINITY.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>,
Cc: Petr Mladek <pmladek@suse.com>
Cc: Michal Hocko <mhocko@suse.com>,
Cc: Peter Zijlstra <peterz@infradead.org>,
Cc: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
---
kernel/workqueue.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index f5b12c6778cc..82937c0fb21f 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1958,7 +1958,6 @@ static struct worker *create_worker(struct worker_pool *pool)
goto fail;
set_user_nice(worker->task, pool->attrs->nice);
- kthread_bind_mask(worker->task, pool->attrs->cpumask);
/* start the newly created worker */
wake_up_process(worker->task);
@@ -2380,6 +2379,8 @@ static int worker_thread(void *__worker)
struct worker *worker = __worker;
struct worker_pool *pool = worker->pool;
+ current->flags |= PF_NO_SETAFFINITY;
+
/* attach the worker to the pool */
worker_attach_to_pool(worker, pool);
@@ -2494,6 +2495,7 @@ static int rescuer_thread(void *__rescuer)
struct list_head *scheduled = &rescuer->scheduled;
bool should_stop;
+ current->flags |= PF_NO_SETAFFINITY;
set_user_nice(current, RESCUER_NICE_LEVEL);
/*
@@ -4279,7 +4281,6 @@ static int init_rescuer(struct workqueue_struct *wq)
}
wq->rescuer = rescuer;
- kthread_bind_mask(rescuer->task, cpu_possible_mask);
wake_up_process(rescuer->task);
return 0;
--
2.19.1.6.gb485710b
next prev parent reply other threads:[~2022-08-04 8:41 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-04 8:41 [RFC PATCH 0/8] workqueue: Fix for prematurely wakeups and cleanups Lai Jiangshan
2022-08-04 8:41 ` [RFC PATCH 1/8] workqueue: Unconditionally set cpumask in worker_attach_to_pool() Lai Jiangshan
2022-08-16 21:18 ` Tejun Heo
2022-08-18 14:39 ` Lai Jiangshan
2022-09-12 7:54 ` Peter Zijlstra
2022-08-04 8:41 ` [RFC PATCH 2/8] workqueue: Make create_worker() safe against prematurely wakeups Lai Jiangshan
[not found] ` <20220804123520.1660-1-hdanton@sina.com>
2022-08-05 2:30 ` Lai Jiangshan
2022-08-16 21:46 ` Tejun Heo
2022-08-04 8:41 ` Lai Jiangshan [this message]
2022-08-04 8:41 ` [RFC PATCH 4/8] workqueue: Set/Clear PF_WQ_WORKER while attaching/detaching Lai Jiangshan
2022-08-04 8:41 ` [RFC PATCH 5/8] workqueue: Use worker_set_flags() in worker_enter_idle() Lai Jiangshan
2022-08-04 8:41 ` [RFC PATCH 6/8] workqueue: Simplify the starting of the newly created worker Lai Jiangshan
2022-08-04 8:41 ` [RFC PATCH 7/8] workqueue: Remove the outer loop in maybe_create_worker() Lai Jiangshan
2022-08-16 22:08 ` Tejun Heo
2022-08-18 14:44 ` Lai Jiangshan
2022-08-19 17:29 ` Tejun Heo
2022-08-04 8:41 ` [RFC PATCH 8/8] workqueue: Move the locking out of maybe_create_worker() Lai Jiangshan
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