Re: [PANIC] page fault -> bremfree: removing a buffer not on a queue

On Wed, 18 Feb 2004, Andreas Kohn wrote:

> > You've probably tripped over the incompatibility between KSE and the
> > nvidia driver.  You will want to use libmap to remap libpthread to libc_r
> > until nVidia issues a fixed driver. please email them :-)
> >
> > I believe this is in UPDATING.
> >
> > libGL links against pthreads.
> Hello,
>
> My libmap.conf contains currently:
>
> libpthread.so.1 libc_r.so.5
> libpthread.so   libc_r.so
>
> which is how I understood the UPDATING entry. Without these entries or
> when mapping libc_r to libpthread, OpenGL applications will core dump.

ok, scratch that idea :)

> I understand that mentioning "libGLcore + NVidia" makes one think about
> the pthread issues, but I don't think that this is the case here.
>
> I did the linking of the same application again a few minutes ago, and
> it worked. The messages I do remember did say something that the
> libGLcore.so was invalid. I did not reinstall the nvidia drivers after
> the crash because everything worked, so I really cannot see what could
> have happened.
> Perhaps some stupid bit flipped at the wrong place and time, and
> triggered everything else (linking triggered hard disk activity, hard
> disk activity and xawtv triggered panic, panic happened at bad moment so
> the bremfree thing happened. That is currently my "explanation" :/)

bremfree tends to be an innocent bystander to other kernel drive-by
memory-corruption issues.  Most likely the buffer it was trying to clear
was corrupted by something else going bad and it triggers its sanity
checks to keep from flushing bad data.  If you had a build explode at the
same time, its possible your machine just happen to glitch at taht point.

Doug White                    |  FreeBSD: The Power to Serve
dwhite_at_gumbysoft.com          |  www.FreeBSD.org