kern/39914: KASSERT(LIST_EMPTY(&vp->v_dirtyblkhd)) failed when unmounting ext2fs

[rmind%netbsd.org@localhost]

>Number:         39914
>Category:       kern
>Synopsis:       KASSERT(LIST_EMPTY(&vp->v_dirtyblkhd)) failed when unmounting 
>ext2fs
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Nov 13 17:25:00 +0000 2008
>Originator:     Mindaugas Rasiukevicius
>Release:        5.99.1
>Organization:
        The NetBSD Foundation
>Environment:
>Description:

Could not get core dump, but:

panic: kernel diagnostic assertion "LIST_EMPTY(&vp->v_dirtyblkhd) failed:
file "/home/netbsd/src-shm/sys/kern/vfs_subr.c", line 872
fatal breakpoint trap in supervisor mode
trap type 1 code 0 eip c017c81c cs 8 eflags 246 cr2 bb903000 ilevel 0
Stopped in pid 6442.1 (umount) at       netbsd:breakpoint+0x4:  popl   %ebp

db{1}> bt
breakpoint() at netbsd:breakpoint+0x4
panic() at netbsd:panic+x1aa
__kernassert() at netbsd:__kernassert+0x39
vinvalbuf(cbfacad4,1,ffffffff,cc486a20,0,0,cc2cbbcc,80000001,cc2cbbbc,4000) at 
netbsd:spec_close+0x87
VOP_CLOSE() at 0x68
ext2fs_unmount() at netbsd:ext2fd_unmount+0x9e
VFS_UNMOUNT() at netbsd:VFS_UNMOUNT+0x26
dounmount() at netbsd:dounmount+0xb0
sys_unmount() at netbsd:sys_unmount+0x10b
syscall() at netbsd:syscall+0xb1

db{1}> show vnode cbfacad4
OBJECT 0xcbfacad4: locked=0, pgops=0xc0481420, npages=0, refs=1

VNODE flags 4030<MPSAFE,LOCKSWORK,ONWORKLST>
mp 0xcbe0861c numoutput 0 size 0x0 writesize 0x0
data 0xcbfaa938 writecount 0 holdcnt 740
tag VT_UFS(1) type VBLK(3) mount 0xcbe0861c typedata 0xcbfaa938
v_lock 0xcbfacb74 v_vnlock 0xcbfacb74

>How-To-Repeat:
        mount ext2 file system
        some activity on file system (eg. build)
        umount
>Fix: