kern/123908: panic: vinvalbuf: dirty bufs

[Nejc Skoberne]

>Number:         123908
>Category:       kern
>Synopsis:       panic: vinvalbuf: dirty bufs
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu May 22 17:40:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Nejc Skoberne
>Release:        RELENG_7
>Organization:
>Environment:
FreeBSD Kizej.domain.com 7.0-STABLE FreeBSD 7.0-STABLE #0: Wed May 21 09:56:39 CEST 2008     root at iFreeBSD.domain.local:/usr/src/sys/i386/compile/MYKERNEL  i386
>Description:
I was trying to make devd automount my USB stick and I stumbled upon a page fault, when I tried to also automatically unmount the usb drive. 

panic: vinvalbuf: dirty bufs
cpuid = 1
Uptime: 5m7s

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address	= 0x0
fault code		= supervisor write, page not present
instruction pointer	= 0x20:0xc046e8db
stack pointer		= 0x28:0xe79df3c0
frame pointer		= 0x28:0xe79df3dc
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, def32 1, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 1102 (ps)
trap number		= 12


>How-To-Repeat:
Add this to /etc/devd.conf:

attach 20 {
        device-name "umass0";
        action "sleep 2; \
                sh /etc/rc.d/devfs restart; \
                /sbin/kldload msdosfs; \
                /sbin/mount /dev/da0s1; \
                /usr/local/sbin/usbsync";
};

detach 20 {
        device-name "umass0";
        action "/sbin/umount /dev/da0s1; \
                /sbin/kldunload msdosfs";
};

restart devd and then plug in the USB stick device. It is nicely mounted into /mnt. Then unplug it - it is normal that this gives an error since it tries to unmount not-any-more-existing device. 

If you now plug it back in, the kernel page fault happens.

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: