Xen dom0 panic on bp diagnostic

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

Hi,
with 4.99.48, a Xen dom0 kernel panics when starting a domU kernel with a
buffer-related assert failure:
panic: kernel diagnostic assertion "LIST_EMPTY(&bp->b_dep)" failed: file 
"../../../../ufs/ffs/ffs_softdep.c", line 3825
Stopped in pid 0.4 (system) at  netbsd:breakpoint+0x1:  ret
db> tr                             
breakpoint(c08ea9f4,c084aeb1,c087d543,c087c290,ef1) at netbsd:breakpoint+0x1
__kernassert(c084aeb1,c087c290,ef1,c087d543,0) at netbsd:__kernassert+0x39
softdep_disk_write_complete(c0d0cf00,0,c6582c2c,c04ea817,c0d0cf00) at 
netbsd:softdep_disk_write_complete+0x63
biodone2(0,c64fb284,c6582c5c,c042f97e,0) at netbsd:biodone2+0x19
biointr(0,c6582c58,c04201e4,0,0) at netbsd:biointr+0x2c
softint_thread(c64fb004,0,c010006d,c0100065,c010006d) at 
netbsd:softint_thread+0x7e

Note that softdep is in the kernel, but no mounted partition use it.
Removing SOFTDEP from kernel config triggers another KASSERT later in the
code:
LL" failed: file "../../../../kern/kern_condvar.c", line 94
Stopped in pid 0.4 (system) at  netbsd:breakpoint+0x1:  ret
db> tr
breakpoint(c08e0744,c0841e51,c087eb94,c087ebc4,5e) at netbsd:breakpoint+0x1
__kernassert(c0841e51,c087ebc4,5e,c087eb94,c098d0a0) at netbsd:__kernassert+0x39
cv_destroy(c0cef58c,c0beffc0,c6568bfc,c06a7aa4,c0cef500) at 
netbsd:cv_destroy+0x57
buf_destroy(c0cef500,ffffffff,c0d282c0,c04e18d7,c6568c14) at 
netbsd:buf_destroy+0x1b
xbdback_iodone(c0cef500,0,c6568c2c,c04e18d7,c0cef500) at 
netbsd:xbdback_iodone+0x84
biodone2(0,c5d5e284,c6568c5c,c0426a3e,0) at netbsd:biodone2+0x74
biointr(0,c6568c58,c04172a4,0,0) at netbsd:biointr+0x2c
softint_thread(c5d5e004,0,c010006d,c0100065,c010006d) at 
netbsd:softint_thread+0x7e


Trying to reboot from debugger gives:
db> reb
syncing disks... ex0: uplistptr was 0
8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 giving up
Printing vnodes for busy buffers
vnode @ 0xc5d9ab28, flags (280010<MPSAFE,CLEAN,INACTREDO>)
        tag VT_UFS(1), type VBLK(3), usecount 3268, writecount 0, holdcount 101
        freelisthd 0x0, mount 0xc0cf9000, data 0xc7dc286c
        tag VT_UFS, ino 1268864, on dev 0, 4 flags 0x0, effnlink 1, nlink 1
        mode 060640, owner 0, group 5, size 0 not locked
vnode @ 0xc5d9ab28, flags (280010<MPSAFE,CLEAN,INACTREDO>)
        tag VT_UFS(1), type VBLK(3), usecount 3268, writecount 0, holdcount 101
        freelisthd 0x0, mount 0xc0cf9000, data 0xc7dc286c
        tag VT_UFS, ino 1268864, on dev 0, 4 flags 0x0, effnlink 1, nlink 1
        mode 060640, owner 0, group 5, size 0 not locked
vnode @ 0xc5d9ab28, flags (280010<MPSAFE,CLEAN,INACTREDO>)
        tag VT_UFS(1), type VBLK(3), usecount 3268, writecount 0, holdcount 101
        freelisthd 0x0, mount 0xc0cf9000, data 0xc7dc286c
        tag VT_UFS, ino 1268864, on dev 0, 4 flags 0x0, effnlink 1, nlink 1
        mode 060640, owner 0, group 5, size 0 not locked
vnode @ 0xc5d9ab28, flags (280010<MPSAFE,CLEAN,INACTREDO>)
        tag VT_UFS(1), type VBLK(3), usecount 3268, writecount 0, holdcount 101
        freelisthd 0x0, mount 0xc0cf9000, data 0xc7dc286c
        tag VT_UFS, ino 1268864, on dev 0, 4 flags 0x0, effnlink 1, nlink 1
        mode 060640, owner 0, group 5, size 0 not locked
vnode @ 0xc5d9ab28, flags (280010<MPSAFE,CLEAN,INACTREDO>)
        tag VT_UFS(1), type VBLK(3), usecount 3268, writecount 0, holdcount 101
        freelisthd 0x0, mount 0xc0cf9000, data 0xc7dc286c
        tag VT_UFS, ino 1268864, on dev 0, 4 flags 0x0, effnlink 1, nlink 1
        mode 060640, owner 0, group 5, size 0 not locked
vnode @ 0xc5d9ab28, flags (280010<MPSAFE,CLEAN,INACTREDO>)
        tag VT_UFS(1), type VBLK(3), usecount 3268, writecount 0, holdcount 101
        freelisthd 0x0, mount 0xc0cf9000, data 0xc7dc286c
        tag VT_UFS, ino 1268864, on dev 0, 4 flags 0x0, effnlink 1, nlink 1
        mode 060640, owner 0, group 5, size 0 not locked
vnode @ 0xc5d9ab28, flags (280010<MPSAFE,CLEAN,INACTREDO>)
        tag VT_UFS(1), type VBLK(3), usecount 3268, writecount 0, holdcount 101
        freelisthd 0x0, mount 0xc0cf9000, data 0xc7dc286c
        tag VT_UFS, ino 1268864, on dev 0, 4 flags 0x0, effnlink 1, nlink 1
        mode 060640, owner 0, group 5, size 0 not locked
vnode @ 0xc7ffb704, flags (204030<MPSAFE,LOCKSWORK,ONWORKLST,INACTREDO>)
        tag VT_UFS(1), type VREG(1), usecount 1, writecount 1, holdcount 2
        freelisthd 0x0, mount 0xc0cf9000, data 0xc7ffcee8
        tag VT_UFS, ino 895007, on dev 0, 4 flags 0x0, effnlink 1, nlink 1
        mode 0100644, owner 0, group 0, size 198302 not locked
giving up


Any idea ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--