Re: [PATCH] KEYS: dispatch key_gc_work to system_wq.

[Jarkko Sakkinen <jarkko@kernel.org>]

On Mon, Oct 26, 2026 at 05:56:05PM +0800, Hillf Danton wrote:
> On Mon, 26 Oct 2026 05:12:18 +0200 Jarkko Sakkinen wrote:
> > schedule_work() dispatches key_gc_work on the per-CPU system_wq, which can
> > choke the queue:
> > 
> > BUG: workqueue lockup - pool cpus=0 node=0 flags=0x2 nice=0 stuck for 30s!
> > 
> > Queue the work on system_dfl_long_wq instead, which is an unbounded wq for
> > long-running tasks i.e., it has the WQ_BOUND flag set and thus cannot hog
> > the CPU core.
> >
> Nope there is no cpu hog at all given cond_resched().

I used wrong term, and it is good that you nitpicked that.

What about workqueue lockup, which I pointed out from transcript?

This does not help.

> Take a break instead then the workqueue has a chance for housekeeping.
> 
> --- x/security/keys/gc.c
> +++ y/security/keys/gc.c
> @@ -270,9 +270,8 @@ contended:
>  
>  maybe_resched:
>  	if (cursor) {
> -		cond_resched();
> -		spin_lock(&key_serial_lock);
> -		goto continue_scanning;
> +		schedule_work(&key_gc_work);
> +		return;
>  	}
>  
>  	/* We've completed the pass.  Set the timer if we need to and queue a
> --

Br, Jarkko