Xen Dom0 panic in uvm pager

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

Hi,

While booting a paravirtualized DomU I got this panic:

panic: kernel diagnostic assertion "pg != NULL" failed: 
file "../../../../uvm/uvm_pager.c", line 524
fatal breakpoint trap in supervisor mode
trap type 1 code 0 rip ffffffff804aa65d cs e030 rflags 246 cr2  7f7ffdfdc000 
cpl 0 rsp ffffa000257789d0
Stopped in pid 0.40 (system) at netbsd:breakpoint+0x5:  leave
breakpoint() at netbsd:breakpoint+0x5
panic() at netbsd:panic+0x255
__kernassert() at netbsd:__kernassert+0x2d
uvm_pageratop() at netbsd:uvm_pageratop+0x5e
nfs_doio_write() at netbsd:nfs_doio_write+0xf1
nfs_doio() at netbsd:nfs_doio+0x1b1
nfssvc_iod() at netbsd:nfssvc_iod+0x181
ds          0x89e0
es          0xe02b
fs          0x8990
gs          0x203
rdi         0
rsi         0xdeadbeef
rbp         0xffffa000257789d0
rbx         0xffffa000257789e0
rdx         0
rcx         0
rax         0x1
r8          0xffffffff80ad44c0  cpu_info_primary
r9          0x1
r10         0xffffa000257788f0
r11         0xffffffff804e6220  xenconscn_putc
r12         0x100
r13         0xffffffff809750a8
r14         0x1
r15         0xffffa0000117e348
rip         0xffffffff804aa65d  breakpoint+0x5
cs          0xe030
rflags      0x246
rsp         0xffffa000257789d0
ss          0xe02b
netbsd:breakpoint+0x5:  leave
db> ps /l
 PID         LID S     FLAGS       STRUCT LWP *               NAME WAIT
 1880          2 3        84   ffffa00025d86020         xenconsole netio
               1 3        84   ffffa00025d27000         xenconsole select
 1933          1 3        84   ffffa00025d867e0               less ttyraw
 399           2 3        84   ffffa00025b9d7c0        xenbackendd netio
               1 3        84   ffffa00025aa1800        xenbackendd parked
 359           2 3        84   ffffa00025ce47e0        xenconsoled netio
               1 3        84   ffffa00025ce4020        xenconsoled select
 404          89 5         4   ffffa00025d273e0          python2.4
               7 3        84   ffffa00025d27ba0          python2.4 socket
               6 3        84   ffffa00025cee040          python2.4 socket
               5 3        84   ffffa00025cee420          python2.4 netio
               4 3        84   ffffa00025cee800          python2.4 parked
               3 3        84   ffffa00025ceebe0          python2.4 select
               2 3        84   ffffa00025ce4400          python2.4 socket
               1 3        84   ffffa00025ce4bc0          python2.4 select
 370           1 3        84   ffffa00025b9d000          python2.4 wait
 381           1 3        84   ffffa00025b9dba0          xenstored select
 260           1 3        84   ffffa00024f10000                ksh pause
 373           1 3        84   ffffa00025aa1040                ksh pause
 366           1 3        84   ffffa00024f103e0              login wait
 369           1 3        84   ffffa00025aa1be0               cron nanoslp
 336           1 3        84   ffffa00025824400              inetd kqueue
 358           1 3        84   ffffa000258247e0               sshd select
 246           1 3        84   ffffa00025824020               sshd select
 107           1 3        84   ffffa00025824bc0            syslogd kqueue
 1             1 3        84   ffffa00024f00ba0               init wait
>0            54 3       204   ffffa00025ec7800               vnd0 vndbp
              46 3       204   ffffa00024f107c0        vmem_rehash vmem_rehash
              45 3       204   ffffa00024f10ba0           aiodoned aiodoned
              44 3       204   ffffa00024f0d040            ioflush syncer
              43 3       204   ffffa00024f0d420           pgdaemon pgdaemon
              42 3       204   ffffa00024f0d800              nfsio nfsiod
              41 3       204   ffffa00024f0dbe0              nfsio nfsiod
           >  40 7       204   ffffa00024f0a020              nfsio
              39 3       204   ffffa00024f0a400              nfsio nfsiod
              38 3       204   ffffa00024f0a7e0          cryptoret crypto_wait
              37 3       204   ffffa0002321f420          atapibus0 sccomp
              36 3       204   ffffa0002321f800               usb4 usbevt
              35 3       204   ffffa0002321fbe0               usb3 usbevt
              34 3       204   ffffa0002321c020               usb2 usbevt
              33 3       204   ffffa0002321c400               usb1 usbevt
              32 3       204   ffffa00024f0abc0         usbtask-dr usbtsk
              31 3       204   ffffa0002321f040         usbtask-hc usbtsk
              30 3       204   ffffa00024f007c0               usb0 usbevt
              29 3       204   ffffa00024f00000             xenbus rdst
              28 3       204   ffffa00024f003e0           xenwatch evtsq
              19 3       204   ffffa0002321c7e0            atabus5 atath
              18 3       204   ffffa0002321cbc0            atabus4 atath
              17 3       204   ffffa0002321b000            atabus3 atath
              16 3       204   ffffa0002321b3e0            atabus2 atath
              15 3       204   ffffa0002321b7c0            atabus1 atath
              14 3       204   ffffa0002321bba0            atabus0 atath
              13 3       204   ffffa00023213040               pms0 pmsreset
              11 3       204   ffffa00023213800             sysmon smtaskq
              10 3       204   ffffa00023213be0           pmfevent pmfevent
               9 3       204   ffffa0002320c020            cachegc cachegc
               8 3       204   ffffa0002320c400              vrele vrele
               7 3       204   ffffa0002320c7e0            xcall/0 xcall
               6 1       204   ffffa0002320cbc0          softser/0
               5 1       204   ffffa0002320a000          softclk/0
               4 1       204   ffffa0002320a3e0          softbio/0
               3 1       204   ffffa0002320a7c0          softnet/0
               2 1       205   ffffa0002320aba0             idle/0
               1 3       204   ffffffff80a8ede0            swapper schedule
 1979          1 5         4   ffffa00025b9d3e0          python2.4
db>