Re: 2.5 Problem Status Report

Jens Axboe
2002-09-11T10:20:38Z

On Wed, Sep 11 2002, Oleg Drokin wrote:
> Hello!
>
> On Wed, Sep 11, 2002 at 09:38:25AM +0200, Ingo Molnar wrote:
>
> > > I have preemption disabled.
> > nevertheless please print out preempt_count() in sched.c - since the big
> > IRQ cleanups we use the preemption count even if preemption is disabled.
> > this way we'll know what kind of problem happened - a stuck softirq count,
> > a stuck hardirq count or an underflow?
>
> You was exactly right. preemption count is -1. I inserted chack in
> dec_preempt_count() and here is updated correct stacktrace. Seems
> like ide_unmap_buffer is called with some bogus data or something like
> that. Also I guess the bug is only visible with debug highmem = ON and
> highmem enabled.

ok I see the bug. it's due to the imbalanced nature of ide_map_buffer()
vs ide_unmap_buffer(). i'll cook up a fix right away.

--
Jens Axboe