kern/48078: xen LOCKDEBUG immediate panic when vcpus=2

[marcotte%panix.com@localhost]

>Number:         48078
>Category:       kern
>Synopsis:       xen LOCKDEBUG immediate panic when vcpus=2
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jul 24 03:20:00 +0000 2013
>Originator:     Brian Marcotte
>Release:        6.1
>Organization:
Public Access Networks, Corp.
>Environment:
NetBSD dw15.panix.com 6.1 NetBSD 6.1 (PANIX-XEN-WEB-DEBUG) #0: Tue Jul 23 
22:09:01 EDT 2013  
root%juggler.panix.com@localhost:/misc/obj/misc/devel/netbsd/6.1/src/sys/arch/i386/compile/PANIX-XEN-WEB-DEBUG
 i386
>Description:
When booting NetBSD/xen with options DEBUG, DIAGNOSTIC, LOCKDEBUG and
vcpus=2, I get an immediate panic.

I added those options to try to get more information about this occasional
panic:

  uvm_fault(0xc1f27a30, 0, 1) -> 0xe
  fatal page fault in supervisor mode
  trap type 6 code 0 eip c01c0d97 cs 9 eflags 10246 cr2 44 ilevel 0
  panic: trap
  cpu0: Begin traceback...
  panic(c03adbe4,cf0c3a98,cf0c3a98,c01c0d97,9,10246,44,0,44,0) at 
netbsd:panic+0x18
  trap() at netbsd:trap+0xb51
  --- trap (number 6) ---
  
kauth_cred_geteuid(cf0c3c9c,0,bf7fdde4,cf0c3cbc,bf7fdf4c,100,cf0c3c8c,c22c6020,c0c5a8a0,4)
 at netbsd:kauth_cred_geteuid+0x7
  
sysctl_dispatch(cf0c3c8c,4,bf7fdde4,cf0c3cbc,bf7fdf4c,100,cf0c3c8c,c22c6020,c0c5a8a0,cf0c3cbc)
 at netbsd:sysctl_dispatch+0xb7
  
sys___sysctl(c22c6020,cf0c3d00,cf0c3d28,ca,bb782000,0,cf0c3d00,c2212384,2,bb7a6ef7)
 at netbsd:sys___sysctl+0xea
  
syscall(cf0c3d48,bb7900b3,ab,bf7f001f,bb79001f,4,bf7fdde4,bf7fddb0,bb7c65bc,bf7fdde0)
 at netbsd:syscall+0xaa
  cpu0: End traceback...

I can open a separate ticket on that later.

Here is the 6.1 boot and panic:

NetBSD 6.1 (XEN3PAE_DOMU_DEBUG) #0: Tue Jul 23 22:25:49 EDT 2013
      
root%juggler.panix.com@localhost:/misc/obj/misc/devel/netbsd/6.1/src/sys/arch/i386/compile/XEN3PAE_DOMU_DEBUG
total memory = 500 MB
avail memory = 483 MB
cprng kernel: WARNING insufficient entropy at creation.
mainbus0 (root)
hypervisor0 at mainbus0: Xen version 4.2.2
vcpu0 at hypervisor0: Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz, id 
0x10676
vcpu1 at hypervisor0: Intel(R) Xeon(R) CPU           E5410  @ 2.33GHz, id 
0x10676
xenbus0 at hypervisor0: Xen Virtual Bus Interface
xencons0 at hypervisor0: Xen Virtual Console Driver
npx0 at hypervisor0: using exception 16
panic: lockdebug_lookup: uninitialized lock (lock=0xc134e4a8, from=c044839a)
fatal breakpoint trap in supervisor mode
trap type 1 code 0 eip c0137814 cs 9 eflags 246 cr2 0 ilevel 8
Stopped in pid 0.1 (system) at  netbsd:breakpoint+0x4:  popl    %ebp
breakpoint(c04ce50f,c050e5e0,c04ce6f8,c07cbaec,c0474143,c134e4a8,c04f2b80,c044839a,c07cbae0,c0378f08)
 at netbsd:breakpoint+0x4
vpanic(c04ce6f8,c07cbaec,c07cbb14,c0370a64,c04ce6f8,c134e4a8,c044839a,0,c07cbb00,6)
 at netbsd:vpanic+0x218
panic(c04ce6f8,c134e4a8,c044839a,0,c07cbb00,6,c04e8c14,0,c134d000,c134e4a8) at 
netbsd:panic+0x18
lockdebug_wantlock(c134e4a8,c044839a,0,0,c0231102,c04e9faa,c044836d,0,c134d000,c050cb00)
 at netbsd:lockdebug_wantlock+0x1b4
mutex_enter(c134e4a8,5,47216003,5,0,5c8,5c8,0,47138000,5) at 
netbsd:mutex_enter+0x36c
xen_kpm_sync(c050cb00,6b9,47216003,5,3,0,0,c03709ba,c07cbbdc,c04467a3) at 
netbsd:xen_kpm_sync+0x13a
pmap_growkernel(d7958000,d7158000,800000,c07cbc78,c0514540,0,0,1,41727,0) at 
netbsd:pmap_growkernel+0x34d
uvm_map_prepare(c05146c0,d7158000,800000,c0514540,0,0,1,41727,c07cbca4,0) at 
netbsd:uvm_map_prepare+0x26e
uvm_map(c05146c0,c051456c,800000,c0514540,0,0,1,41727,6400,c07cbd40) at 
netbsd:uvm_map+0x85
ubc_init(c04b0dab,6,3,0,c064c560,c0626d14,7cc000,c0658200,c07cbd38,c0240ce7) at 
netbsd:ubc_init+0x198
main(0,0,0,0,0,0,0,0,0,0) at netbsd:main+0x2a7
ds          c0370011    lockdebug_lock_cpus+0x11
es          c07c0011
fs          c07c0031
gs          c04c0011    copyright+0x222b1
edi         c07cbaec
esi         c04ce6f8    copyright+0x30998
ebp         c07cbaa8
ebx         104
edx         0
ecx         8
eax         1
eip         c0137814    breakpoint+0x4
cs          9
eflags      246
esp         c07cbaa8
ss          11
netbsd:breakpoint+0x4:  popl    %ebp
db{0}>

>How-To-Repeat:
I added these options to XEN3PAE_DOMU:

options         DIAGNOSTIC
options         DEBUG
options         LOCKDEBUG
makeoptions     DEBUG="-g"      # compile full symbol table

set vcpus=2

When I remove LOCKDEBUG or set vcpus=1 it boots.
It also panics on -current

>Fix:
Unknown.