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kthread: unpark only parked kthread

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Calling into kthread unparking unconditionally is mostly harmless when
the kthread is already unparked. The wake up is then simply ignored
because the target is not in TASK_PARKED state.

However if the kthread is per CPU, the wake up is preceded by a call
to kthread_bind() which expects the task to be inactive and in
TASK_PARKED state, which obviously isn't the case if it is unparked.

As a result, calling kthread_stop() on an unparked per-cpu kthread
triggers such a warning:

	WARNING: CPU: 0 PID: 11 at kernel/kthread.c:525 __kthread_bind_mask kernel/kthread.c:525
	 <TASK>
	 kthread_stop+0x17a/0x630 kernel/kthread.c:707
	 destroy_workqueue+0x136/0xc40 kernel/workqueue.c:5810
	 wg_destruct+0x1e2/0x2e0 drivers/net/wireguard/device.c:257
	 netdev_run_todo+0xe1a/0x1000 net/core/dev.c:10693
	 default_device_exit_batch+0xa14/0xa90 net/core/dev.c:11769
	 ops_exit_list net/core/net_namespace.c:178 [inline]
	 cleanup_net+0x89d/0xcc0 net/core/net_namespace.c:640
	 process_one_work kernel/workqueue.c:3231 [inline]
	 process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
	 worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
	 kthread+0x2f0/0x390 kernel/kthread.c:389
	 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
	 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
	 </TASK>

Fix this with skipping unecessary unparking while stopping a kthread.

Link: https://lkml.kernel.org/r/20240913214634.12557-1-frederic@kernel.org
Fixes: 5c25b5ff89 ("workqueue: Tag bound workers with KTHREAD_IS_PER_CPU")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reported-by: syzbot+943d34fa3cf2191e3068@syzkaller.appspotmail.com
Tested-by: syzbot+943d34fa3cf2191e3068@syzkaller.appspotmail.com
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Frederic Weisbecker 2024-09-13 23:46:34 +02:00 committed by Andrew Morton
parent 9a8da05d7a
commit 214e01ad4e
1 changed files with 2 additions and 0 deletions
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2
kernel/kthread.c
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@ -623,6 +623,8 @@ void kthread_unpark(struct task_struct *k)
{
struct kthread *kthread = to_kthread(k);
if (!test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))
return;
/*
* Newly created kthread was parked when the CPU was offline.
* The binding was lost and we need to set it again.