Re: 3 bugs found.

[David Smith <dsmith at redhat dot com>]

David Smith wrote:
> James Dickens wrote:
> > Here are 3 scripts, one line each, they each break the Systemtap one
> > is old, just needs to expand the current bug report.
> >
> > Linux localhost.localdomain 2.6.17-1.2187_FC5 #1 Mon Sep 11 01:17:06
> > EDT 2006 i686 athlon i386 GNU/Linux
>
> Since I've got a similar system (except mine isn't an athlon), I decided 
> to take a look at these.  See stuff below.
>
> > Latest cvs updates as of 2  hours ago.
> >
> > Distro: Fedora FC5
> >
> > Stack fault on the cpu. Halting the machine, This is x86 previously
> > only filed for x86_64
> >
> > probe kernel.function("*") { print(".") }
> >
> > To narrow it down a bit, this causes the same stack fault
> >
> > probe kernel.function("*@kernel/*") { printf("here\n"); }
>
> I've narrowed this one down.  This only happens when probing 
> 'atomic_notifier_call_chain'.
>
> > This one produces an oops, I can post the end of it, if nobudy else
> > can reproduce that has a serial console.
> >
> > probe kernel.function("*@kernel/spinlock.c") { printf("."); }
>
> I've reproduced this one with '_spin_unlock_irqrestore'.  On the console 
> I get:
>
> BUG: spinlock lockup on CPU#0
>
> With those two functions added to the blacklist (I'm not sure that is 
> the right fix, I just want to get past those two functions), the 
> following works correctly:
>
> probe kernel.function("*@kernel/*") { printf("here\n"); }
>
> Now your first probe (probing the entire kernel) still fails.  I'm 
> trying to narrow it down.

I've found it.  If I add '_raw_spin_unlock' to the blacklist (along with 
'atomic_notifier_call_chain' and '_spin_unlock_irqrestore'), then 
probing kernel.function("*") works fine for me on x86.

Note that once again I'm not sure that is the correct fix (adding it to 
the blacklist), I just wanted to get past it.

--
David Smith
dsmith@redhat.com
Red Hat, Inc.
http://www.redhat.com
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