kern/47480: tmpfs panic: panic: kernel diagnostic assertion "cookie != TMPFS_DIRCOOKIE_DOT" failed

[Thomas Klausner <wiz%NetBSD.org@localhost>]

>Number:         47480
>Category:       kern
>Synopsis:       tmpfs panic: panic: kernel diagnostic assertion "cookie != 
>TMPFS_DIRCOOKIE_DOT" failed
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jan 21 13:00:00 +0000 2013
>Originator:     Thomas Klausner
>Release:        NetBSD 6.99.16
>Organization:
>Environment:
        
        
System: NetBSD yt.nih.at 6.99.16 NetBSD 6.99.16 (YT) #37: Mon Jan 21 01:22:59 
CET 2013 wiz%yt.nih.at@localhost:/usr/src/sys/arch/amd64/compile/obj/YT amd64
Architecture: x86_64
Machine: amd64
>Description:
This night my amd64/6.99.16 paniced during a bulk build on a tmpfs.

My setup is
tmpfs on /home/wiz/sandbox type tmpfs (local)
/bin on /home/wiz/sandbox/bin type null (read-only, local)
/sbin on /home/wiz/sandbox/sbin type null (read-only, local)
/lib on /home/wiz/sandbox/lib type null (read-only, local)
/libexec on /home/wiz/sandbox/libexec type null (read-only, local)
/usr/X11R7 on /home/wiz/sandbox/usr/X11R7 type null (read-only, local)
/usr/bin on /home/wiz/sandbox/usr/bin type null (read-only, local)
/usr/games on /home/wiz/sandbox/usr/games type null (read-only, local)
/usr/include on /home/wiz/sandbox/usr/include type null (read-only, local)
/usr/lib on /home/wiz/sandbox/usr/lib type null (read-only, local)
/usr/libdata on /home/wiz/sandbox/usr/libdata type null (read-only, local)
/usr/libexec on /home/wiz/sandbox/usr/libexec type null (read-only, local)
/usr/share on /home/wiz/sandbox/usr/share type null (read-only, local)
/usr/sbin on /home/wiz/sandbox/usr/sbin type null (read-only, local)
/var/mail on /home/wiz/sandbox/var/mail type null (read-only, local)
/usr/src on /home/wiz/sandbox/usr/src type null (read-only, local)
/usr/pkgsrc on /home/wiz/sandbox/usr/pkgsrc type null (local)
/usr/xsrc on /home/wiz/sandbox/usr/xsrc type null (read-only, local)
/packages/6.99.16 on /home/wiz/sandbox/packages type null (local)
/distfiles on /home/wiz/sandbox/distfiles type null (local)

I was sleeping. When I woke up I found the machine had rebooted and
/var/log/messages contained:
Jan 21 01:58:50 yt savecore: reboot after panic: panic: kernel diagnostic 
assertion "cookie != TMPFS_DIRCOOKIE_DOT" failed: filAeR N"I/aNrGc:h iSvPeL/ 
cNvOsT/ sLrOcW/EsRyEsD/ OsN/t mSpYfs/CtAmLpLf s.h"6,7  l4i nEeX I9T3  4  6

This actually looks like two interspersed strings on might be:

file "/archive/cvs/src/sys/[f?]s/tmpfs/tmpfs.h [4936?]
Line 4930 of that file here is
        KASSERT(cookie != TMPFS_DIRCOOKIE_DOT);

The other might be:
[W?]ARNING: SPL NOT LOWERED ON SY[S?]CALL EXIT


/var/crash contains:
-rw-------   1 root  wheel    193984319 Jan 21 01:59 netbsd.7.core.gz
-rw-------   1 root  wheel       373764 Jan 21 01:59 netbsd.7.gz
which don't look nearly big enough to be useable, but if somewants has specific 
ideas
what to look for, send me gdb commands.
For the record, the kernel was
-rwxr-xr-x  1 root  wheel  9923436 Jan 21 01:23 
/netbsd.6.99.16h.otus-cvs.32tx.debug4reallythistime (don't ask)
>How-To-Repeat:
Do bulk builds on tmpfs.
Wait.
Have bad luck.
>Fix:
Yes please.

>Unformatted: