Re: Unable to do IA64 stacktrace in early boot

From: David Mosberger-Tang <dmosberger_at_gmail.com>
Date: 2006-12-22 09:03:00
The libunwind-based unwinder uses it's own primitive allocator to
avoid such problems.  I posted a working patch a couple of months
back.

  --david

On 12/21/06, Ingo Molnar <mingo@redhat.com> wrote:
> On Wed, 2006-12-20 at 22:03 -0700, Matthew Wilcox wrote:
> > > mutex-debug uses DEBUG_LOCKS_WARN_ON() which indirectly calls
> > > dump_stack which the IA64 unwind code (arch/ia64/kernel/unwind.c)
> > calls
> > > kmalloc.  The lockdep tests are run before the slab caches have been
> > > allocated so cpu_cache_get is called with a NULL cachep, hence the
> > > oops.
> >
> > Yup.  I just debugged and fixed the same problem on parisc.  I didn't
> > think to check ia64; I checked to see what x86-64 did.  Unfortunately,
> > the ia64 unwind code seems a lot more subtle and more allocation-happy
> > than the parisc unwind code, so I'm not sure exactly how to fix ia64.
>
> yeah. calling kmalloc() within the unwinder is a no-no. What if the
> unwind happens while kmalloc() is crashing?
>
>         Ingo
> >
>
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Received on Fri Dec 22 09:03:46 2006

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