kdebug> message
Invalid concurrent access to page %p (check), currently accessed by: %ld

kdebug> bt
stack trace for thread 10 "page daemon"
    kernel stack: 0x8016c000 to 0x80170000
frame               caller     <image>:function + offset
 0 8016fb9c (+  48) 8006fa30   <kernel_x86> invoke_command_trampoline(0x8016fc34) + 0x001c
 1 8016fbcc (+  12) 800f8744   <kernel_x86>:arch_debug_call_with_fault_handler + 0x001b
 2 8016fbd8 (+  48) 8006ec00   <kernel_x86>:debug_call_with_fault_handler + 0x0060
 3 8016fc08 (+  64) 8006fc89   <kernel_x86>:invoke_debugger_command + 0x00b9
 4 8016fc48 (+  64) 8006fab5   <kernel_x86> invoke_pipe_segment(debugger_command_pipe*: 0x852e9030, int32: 0, 0x0 "<NULL>") + 0x0079
 5 8016fc88 (+  64) 8006fdf4   <kernel_x86>:invoke_debugger_command_pipe + 0x009c
 6 8016fcc8 (+  48) 800717ac   <kernel_x86> ExpressionParser<0x8016fd78>::_ParseCommandPipe(0x8016fd74) + 0x0234
 7 8016fcf8 (+  64) 80070be6   <kernel_x86> ExpressionParser<0x8016fd78>::EvaluateCommand(0x8014bce0 "bt", 0x8016fd74) + 0x02ba
 8 8016fd38 (+ 224) 80072bc0   <kernel_x86>:evaluate_debug_command + 0x0080
 9 8016fe18 (+  64) 8006d6fe   <kernel_x86> kernel_debugger_loop(0x8012bbd7 "PANIC: ", 0x8013b7c0 "Invalid concurrent access to page %p (check), currently accessed by: %ld", 0x8016fec4 "Ü", int32: 0) + 0x02de
10 8016fe58 (+  48) 8006d958   <kernel_x86> kernel_debugger_internal(0x8012bbd7 "PANIC: ", 0x8013b7c0 "Invalid concurrent access to page %p (check), currently accessed by: %ld", 0x8016fec4 "Ü", int32: 0) + 0x0048
11 8016fe88 (+  48) 8006ed98   <kernel_x86>:panic + 0x0024
12 8016feb8 (+  64) 800e3c9c   <kernel_x86>:vm_page_requeue + 0x0060
13 8016fef8 (+  64) 800e0a38   <kernel_x86> idle_scan_active_pages(page_stats&:0x8016ffc4) + 0x0078
14 8016ff38 (+  64) 800e15da   <kernel_x86> page_daemon_idle_scan(page_stats&: 0x8016ffc4) + 0x0072
15 8016ff78 (+  96) 800e16fa   <kernel_x86> page_daemon(NULL) + 0x0092
16 8016ffd8 (+  32) 80060f6f   <kernel_x86> _create_kernel_thread_kentry() + 0x001b
17 8016fff8 (+2145976328) 80060f0c   <kernel_x86> thread_kthread_exit() + 0x0000

kdebug> page -m 0x8300dc84
PAGE: 0x8300dc84
queue_next,prev: 0x83009dc8, 0x00000000
physical_number: 0x503
cache:           0xccd4b660
cache_offset:    0
cache_next:      0x8300dcb0
state:           active
wired_count:     0
usage_count:     8
busy:            1
busy_writing:    0
accessed:        0
modified:        0
accessor:        -1
area mappings:
  0xcd945500 (1895)
  0xccd66460 (1858)
  0xce53f730 (1801)
  0xccd62fa0 (1772)
  0xcd93bd70 (1739)
  0xccd621e0 (1732)
  0xcd93ba50 (1697)
  0xccd628c0 (1659)
  0xccd55050 (1547)
  0x82029b40 (1451)
  0x82029640 (1395)
  0xcd9259b0 (1156)
  0xce519a00 (1143)
  0xcd925910 (1098)
  0xcd925460 (1003)
  0xccd3e870 (742)
all mappings:
  aspace 1, area 3: 0x81035000 (rw accessed)
  aspace 1, area 3: 0x81077000 (rw accessed)
  aspace 53, area 742: 0x100000 (r-)
  aspace 62, area 1003: 0x100000 (r-)
  aspace 69, area 1098: 0x100000 (r-)
  aspace 70, area 1143: 0x100000 (r-)
  aspace 71, area 1156: 0x100000 (r-)
  aspace 83, area 1395: 0x100000 (r-)
  aspace 92, area 1451: 0x100000 (r-)
  aspace 103, area 1547: 0x100000 (r-)
  aspace 110, area 1659: 0x100000 (r-)
  aspace 111, area 1697: 0x100000 (r-)
  aspace 113, area 1739: 0x100000 (r-)
  aspace 114, area 1732: 0x100000 (r-)
  aspace 115, area 1772: 0x100000 (r-)
  aspace 116, area 1801: 0x100000 (r-)
  aspace 117, area 1858: 0x100000 (r-)
  aspace 118, area 1895: 0x100000 (r-)

kdebug> info
kernel build: Feb 20 2010 16:02:41
SVN revision: 35537

cpu count: 4, active times:
  [1] 697396
  [2] 2788286
  [3] 1082799
  [4] 2571001
pages:          34441 (786144 max)
sems:           469 (65536 max)
ports:          47 (4096 max)
threads:        83 (4096 max)
teams:          19 (2048 max)