freebsd stable - Jan 2005 - "Data modified on freelist"?

I'm running 4-STABLE / 4.11-PRERELEASE (CVS tag=RELENG_4), dated 2004-
12-10, on an AMD Athlon system at home.

Last night, I got the following message from the kernel:

     Data modified on freelist: word 14 of object 0xc2aff700
     size 256 previous type FFS node (0xdeadc09e != 0xdeadc0de)

What does this mean?  Is it a reason for me to worry?  Any ideas on
what might have caused it or what I should do about it?

Rich Wales            richw@richw.org            http://www.richw.org

Rich Wales <richw@richw.org> writes:
> I'm running 4-STABLE / 4.11-PRERELEASE (CVS tag=RELENG_4), dated 2004-
> 12-10, on an AMD Athlon system at home.
> 
> Last night, I got the following message from the kernel:
> 
>      Data modified on freelist: word 14 of object 0xc2aff700
>      size 256 previous type FFS node (0xdeadc09e != 0xdeadc0de)
> 
> What does this mean?  Is it a reason for me to worry?  Any ideas on
> what might have caused it or what I should do about it?
That's a single bit flipped.  
Assuming you don't have error-correcting memory, it could be 
anything, including a stray cosmic ray...