Re: Fixed strace [ was Re: ls -l is broken ]

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Thu, 2009-05-07 at 14:41 -0400, John David Anglin wrote:
> > On Thu, May 07, 2009 at 01:41:03PM -0400, John David Anglin wrote:
> > > > On Wed, May 06, 2009 at 01:39:49PM -0400, John David Anglin wrote:
> > > > > > The tombstone is:
> > > > > > 
> > > > > > do_page_fault() pid=10205 command='strace' type=15 address=0x407d2f18
> > > > > > vm_start = 0x4068d000, vm_end = 0x4068f000
> > > > > 
> > > > > So, the pointer passed to __canonicalize_funcptr_for_compare is outside
> > > > > the vm range.
> > > > > 
> > > > > Maybe "info sharedlib" will show something.  Need to find out why the
> > > > > address of the function descriptor is outside the vm range.
> > > > > 
> > > > 
> > > > 405c0000-405c2000 rwxp 405c0000 00:00 0 
> > > 
> > > The function pointer address is also outside this range.
> > > 
> > 
> > Sorry, this was with a rebuilt binary, and it lies within this range.
> 
> It's marked rwxp, so why the fault?

That's a bit fascinating ... it means we got into the bad_area: goto of
do_page_fault() somehow even though the vma apparently allowed the fault
and we should have been able to page it in.  Something like this might
explain a lot of our stability problems.

James