Re: [net,PATCH v2] net: ks8851: Reinstate disabling of BHs around IRQ handler

Sebastian Andrzej Siewior
2026-04-13T16:10:04Z

On 2026-04-13 08:44:45 [-0700], Jakub Kicinski wrote:
> On Mon, 13 Apr 2026 14:57:44 +0200 Sebastian Andrzej Siewior wrote:
> > On 2026-04-12 10:51:25 [-0700], Jakub Kicinski wrote:
> > > > Does the backtrace make the problem clearer, with the annotation above ?
> > >
> > > Sebastian, do you have any recommendation here? tl;dr is that the driver does
> > …
> >
> > What about this:
>
> Thanks for taking a look (according to you auto-reply immediately after
> a vacation ;))

;)

> TBH changing the driver feels like a workaround / invitation for a
> whack-a-mole game. I'd prefer to fix the skb allocation.

The problem is that _irq() implicitly disables bh processing but this
does not happen. Forcing this is possible but expensive.
However, I did remove lock from bh_disable() on RT.

Marek: from which kernel version was this backtrace?

> Is there any way we can check if any locks which were _irq() on non-RT
> are held?

lockdep has a list of locks which are acquired but it does not see if it
is _irq() or not. It only records it was acquired.

Sebastian