Subject: Re: linux-next: User Mode Linux broken

From: Thomas Gleixner <[email-masked]>
Date: Fri, 22 Oct 2010 09:03:44 +0200 (CEST)

On Thu, 21 Oct 2010, Richard Weinberger wrote:
> Am Donnerstag 21 Oktober 2010, 21:45:35 schrieb Thomas Gleixner:
> > Why shold it solve it ? irq_enable is set to compat_irq_enable which
> > in turn calls chip->enable.
> > 
> > So how's that different ?
> 
> I took a closer look on the issue.
> 
> check_irq_resend() gets called before irq_chip_set_defaults().
> In the first call to check_irq_resend() desc->irq_data.chip->irq_enable is 
> NULL. UML dies due to a NULL-pointer dereference...
> 
> I don't know why check_irq_resend() is called before irq_chip_set_defaults().
> It's your code. ;-)

Well, but it only gets called via enable_irq(). So that means
something is calling enable_irq _before_ request/setup_irq().

arch/um/kernel/irq.c:init_IRQ() does that :)

Thanks,

	tglx