panic: bad pte

Doug White dwhite at
Thu Apr 15 19:42:01 PDT 2004

On Sun, 11 Apr 2004, Andrea Campi wrote:

> Hi,
> I know this has been mentioned before on the list, and probably I should
> know what to make of it, but still...
> I'm getting this panic from time to time (not easy to reproduce, no
> apparent pattern):
> TPTE at 0xbfca06ec  IS ZERO @ VA 281bb000
> panic: bad pte
> at line 2558 in file /usr/src/sys/i386/i386/pmap.c
> I was silly and just typed c so nothing more to work on I'm afraid.
> Basically, what I'm asking is: what's it about? Is it hardware-related,
> is it a know problem, or should I wait for it to happen again and look
> into getting more details?

A pte is a Page Table Entry and has to do with memory mapping.  This
particular panic is triggered when it discovers a page its trying to
remove from a process doesn't appear to exist.  This can be caused by bad
memory corrupting the page tables, or it could be a bug.

Someone wwhos familiar with the pagetable layout may want to investigate
the given VA to see whats corrupted.  That prson isn't me unfortunately :)

Try to capture a crashdump and save it and the debugging kernel somewhere
in case someone wants to look at it offline.

Doug White                    |  FreeBSD: The Power to Serve
dwhite at          |

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