Re: panic: pmap_enter: attempted pmap_enter on 4MB page

Jilles Tjoelker wrote:
> Hello,
> 
> Yesterday our 5-CURRENT box panicked with panic: pmap_enter: attempted
> pmap_enter on 4MB page.
[..]
> (kgdb) p va
> $1 = 689672192
> (kgdb) p pte
> $2 = (pt_entry_t *) 0xbfca46e4
> (kgdb) p origpte
> $3 = 3503345872
> (kgdb) p (void *)va
> $4 = (void *) 0x291b9000
> (kgdb) p (void *)origpte
> $5 = (void *) 0xd0d0d0d0
> (kgdb) # 

AHA!  origpte being 0xd0d0d0d0 means that something really came unstuck
because that is the fill pattern that userland malloc(3) uses.  The
4MB page thing is a red herring, it just happens that PG_PS (0x80) is
a set bit in the fill pattern.

Now to find the source. :-(  Are you getting this repeatably?  If somebody
is able to (relatively) easily provoke this, there are a few things I'd
like to try (shotgun diagnostics, but its better than nothing).

Cheers,
-Peter
--
Peter Wemm - peter_at_wemm.org; peter_at_FreeBSD.org; peter_at_yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5