Re: [PATCH RFC 04/29] fsverity: add per-sb workqueue for post read processing

Christoph Hellwig
2025-08-12T07:43:54Z

> On Mon, Aug 11, 2025 at 01:45:19PM +0200, Christoph Hellwig wrote:
> > On Mon, Jul 28, 2025 at 10:30:08PM +0200, Andrey Albershteyn wrote:
> > > From: Andrey Albershteyn <aalbersh@redhat.com>
> > >
> > > For XFS, fsverity's global workqueue is not really suitable due to:
> > >
> > > 1. High priority workqueues are used within XFS to ensure that data
> > > IO completion cannot stall processing of journal IO completions.
> > > Hence using a WQ_HIGHPRI workqueue directly in the user data IO
> > > path is a potential filesystem livelock/deadlock vector.
> >
> > Do they? I though the whole point of WQ_HIGHPRI was that they'd
> > have separate rescue workers to avoid any global pool effects.
>
> HIGHPRI and MEM_RECLAIM are orthogonal. HIGHPRI makes the workqueue use
> worker pools with high priority, so all work items would execute at MIN_NICE
> (-20). Hmm... actually, rescuer doesn't set priority according to the
> workqueue's, which seems buggy.

Andrey (or others involved with previous versions): is interference
with the log completion workqueue what you ran into?

Tejun, are you going to prepare a patch to fix the rescuer priority?