Bug 16165

Summary: Diskless machine panics during swap
Product: Base System Reporter: dgilbert <dgilbert>
Component: kernAssignee: freebsd-bugs (Nobody) <bugs>
Status: Closed FIXED    
Severity: Affects Only Me    
Priority: Normal    
Version: 4.0-CURRENT   
Hardware: Any   
OS: Any   

Description dgilbert 2000-01-18 02:00:01 UTC 
Machine will panic often.  The signature of the panic that I have
recorded is the following:

fatal trap 12: page fault in kernel mode
curproc: pagedaemon
interupt mask: net bio cam

vn_todev+0x6: movl 0x48(%edx),%eax	(edx and eax are 0x0)
pbgetvp+0x1a
swap_pageer_putpages+0x32b
ufs_vnoperatespec+0x7f
vm_pageout_flush+0x92
vm_page_bits+0x202
vm_pageout_page_free+0x49e
vm_opageout_page_free+0xd8c
fork_trampoline+0x8

I think the vm_pageout_page_free looks suspicious --- that function doesn't
look big enough to have such offsets.  fork_trampoline looks like
particularly difficult magic.  I don't know exactly where I should
be heading to track this one down, but I can reproduce it several
times a day on a small diskless machine.

Fix: 

None known.
How-To-Repeat: 
Boot machine, run X, wait.
Comment 1 Matt Dillon freebsd_committer freebsd_triage 2000-01-25 04:51:05 UTC 
State Changed
From-To: open->closed

Grr.  Looks like the swapdev specfs removal crap that unnamed people did 
without consulting with me broke diskless swapping. 

I was able to repeat the bug on my diskless workstation and will commit  
a fix for -current tonight. 

Thanks For the bug report!