Re: [PATCH] rqspinlock: Fix order in raw_res_spin_(un)lock_irq to allow schedule

[Gabriele Monaco]

On Tue, 2026-06-09 at 16:42 +0200, Kumar Kartikeya Dwivedi wrote:
> On Tue Jun 9, 2026 at 3:04 PM CEST, Gabriele Monaco wrote:
> > On Tue, 2026-06-09 at 13:22 +0200, Arnd Bergmann wrote:
> > 
> > > Did you see this cause measurable performance problems,
> > > or did you find it through inspection?
> > 
> > I noticed it while debugging an ENOMEM issue in the test_maps BPF
> > selftest on PREEMPT_RT and this was an obvious cuplrit (irq_work
> > not scheduled during a stress run). Turns out the problem is still
> > there after this fix though.
> 
> I would imagine this to be the least of your problems, I think
> there's a bunch of blockers for complete selftests passing with
> PREEMPT_RT support in BPF.
> 

Well, I'm starting to believe that too..
At the moment on well tuned machines we are only observing ENOMEM
issues in the test_maps and only when it's literally hogging the
allocator (preallocation is off and 100 treads do updates in parallel).

What else are you expecting to fail under PREEMPT_RT?

> > > > Signed-off-by: Gabriele Monaco <gmonaco@xxxxxxxxxx>
> > > 
> > > Acked-by: Arnd Bergmann <arnd@xxxxxxxx> # asm-generic
> 
> The patch makes sense to me as well.
> 
> Acked-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>

Thanks,
Gabriele