Fatal trap 12: page fault while in kernel mode when connecting PPPoE

cmcdonald

Hi, could you add the line net.isr.maxthreads=1 to /boot/loader.conf on both primary and secondary, and try replicating the crash?

w0w

@cmcdonald

Crash on primary, leaving CARP maintenance mode.

db:1:pfs> bt
Tracing pid 12 tid 100063 td 0xfffffe00c498ae40
kdb_enter() at kdb_enter+0x32/frame 0xfffffe001b1f1610
vpanic() at vpanic+0x163/frame 0xfffffe001b1f1740
panic() at panic+0x43/frame 0xfffffe001b1f17a0
trap_fatal() at trap_fatal+0x40c/frame 0xfffffe001b1f1800
trap_pfault() at trap_pfault+0x4f/frame 0xfffffe001b1f1860
calltrap() at calltrap+0x8/frame 0xfffffe001b1f1860
--- trap 0xc, rip = 0xffffffff80fb86d7, rsp = 0xfffffe001b1f1930, rbp = 0xfffffe001b1f19f0 ---
pf_route() at pf_route+0x4e7/frame 0xfffffe001b1f19f0
pf_test() at pf_test+0xd7b/frame 0xfffffe001b1f1b90
pf_check_out() at pf_check_out+0x22/frame 0xfffffe001b1f1bb0
pfil_mbuf_out() at pfil_mbuf_out+0x38/frame 0xfffffe001b1f1be0
ip_output() at ip_output+0xb4a/frame 0xfffffe001b1f1ce0
ip_forward() at ip_forward+0x3c2/frame 0xfffffe001b1f1d90
ip_input() at ip_input+0x6e9/frame 0xfffffe001b1f1df0
swi_net() at swi_net+0x128/frame 0xfffffe001b1f1e60
ithread_loop() at ithread_loop+0x257/frame 0xfffffe001b1f1ef0
fork_exit() at fork_exit+0x7f/frame 0xfffffe001b1f1f30
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe001b1f1f30
--- trap 0xaf34f5ea, rip = 0x56a9887e31914e4f, rsp = 0x4506b2da7d808177, rbp = 0xf56feca9dc25ff3d ---
db:1:pfs>  show registers
cs                        0x20
ds                        0x3b
es                        0x3b
fs                        0x13
gs                        0x1b
ss                        0x28
rax                       0x12
rcx         0xffffffff81457767
rdx         0xfffffe001b1f1250
rbx                      0x100
rsp         0xfffffe001b1f1610
rbp         0xfffffe001b1f1610
rsi                       0x30
rdi         0xffffffff82d40298  vt_conswindow+0x10
r8                           0
r9                           0
r10                          0
r11                          0
r12                          0
r13                          0
r14         0xffffffff813db3a1
r15         0xfffffe00c498ae40
rip         0xffffffff80d38812  kdb_enter+0x32
rflags                    0x86
kdb_enter+0x32: movq    $0,0x2344ff3(%rip)
db:1:pfs>  show pcpu
cpuid        = 0
dynamic pcpu = 0x111df00
curthread    = 0xfffffe00c498ae40: pid 12 tid 100063 critnest 1 "swi1: netisr 6"
curpcb       = 0xfffffe00c498b360
fpcurthread  = none
idlethread   = 0xfffffe00c48d73a0: tid 100003 "idle: cpu0"
self         = 0xffffffff84010000
curpmap      = 0xffffffff83021ab0
tssp         = 0xffffffff84010384
rsp0         = 0xfffffe001b1f2000
kcr3         = 0x80000000c5d25003
ucr3         = 0xffffffffffffffff
scr3         = 0x2f5f9db5f
gs32p        = 0xffffffff84010404
ldt          = 0xffffffff84010444
tss          = 0xffffffff84010434
curvnet      = 0xfffff80001279200
db:1:pfs>  run lockinfo
db:2:lockinfo> show locks
No such command; use "help" to list available commands
db:2:lockinfo>  show alllocks
No such command; use "help" to list available commands
db:2:lockinfo>  show lockedvnods
Locked vnodes
************************************************************************
Fatal trap 12: page fault while in kernel mode
cpuid = 5; apic id = 05

fault virtual address	= 0x50






fault code		= supervisor read data, page not present

Fatal trap 12: page fault while in kernel mode
Fatal trap 12: page fault while in kernel mode
instruction pointer	= 0x20:0xffffffff80fb86d7
cpuid = 1; 
Fatal trap 12: page fault while in kernel mode
apic id = 01
cpuid = 3; stack pointer	        = 0x28:0xfffffe001b1e2930
Fatal trap 12: page fault while in kernel mode

frame pointer	        = 0x28:0xfffffe001b1e29f0
cpuid = 0; apic id = 00
fault virtual address	= 0x50
fault code		= supervisor read data, page not present
fault virtual address	= 0x50
instruction pointer	= 0x20:0xffffffff80fb86d7
stack pointer	        = 0x28:0xfffffe001b1f1930
frame pointer	        = 0x28:0xfffffe001b1f19f0
code segment		= base 0x0, limit 0xfffff, type 0x1b
Fatal trap 12: page fault while in kernel mode
			= DPL 0, pres 1, long 1, def32 0, gran 1
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
cpuid = 6; apic id = 06
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 12 (swi1: netisr 6)
rdi: fffff8028743200e rsi: fffffe00c481e82d rdx: 0000000000000000
rcx: fffffe00c481e370  r8: fffffe001b1f1a50  r9: 0000000000000000
rax: 0000000000000000 rbx: fffff80317e5b8b8 rbp: fffffe001b1f19f0
r10: 0000000000000000 r11: fffffe00c481e370 r12: fffffe00c481e370
r13: 0000000000000002 r14: fffff802f5b13840 r15: fffffe001b1f1c78
trap number		= 12
panic: page fault
cpuid = 0
time = 1695445416
KDB: enter: panic

net.isr.numthreads: 1
net.isr.maxprot: 16
net.isr.defaultqlimit: 256
net.isr.maxqlimit: 10240
net.isr.bindthreads: 0
net.isr.maxthreads: 1
net.isr.dispatch: hybrid

When primary booted, I just selected Reboot in GUI and confirmed, at the same time secondary firewall crashed

db:1:pfs> bt
Tracing pid 0 tid 100007 td 0xfffffe0020565720
kdb_enter() at kdb_enter+0x32/frame 0xfffffe001d7da390
vpanic() at vpanic+0x163/frame 0xfffffe001d7da4c0
panic() at panic+0x43/frame 0xfffffe001d7da520
trap_fatal() at trap_fatal+0x40c/frame 0xfffffe001d7da580
trap_pfault() at trap_pfault+0x4f/frame 0xfffffe001d7da5e0
calltrap() at calltrap+0x8/frame 0xfffffe001d7da5e0
--- trap 0xc, rip = 0xffffffff80fb86d7, rsp = 0xfffffe001d7da6b0, rbp = 0xfffffe001d7da770 ---
pf_route() at pf_route+0x4e7/frame 0xfffffe001d7da770
pf_test() at pf_test+0xd7b/frame 0xfffffe001d7da910
pf_check_out() at pf_check_out+0x22/frame 0xfffffe001d7da930
pfil_mbuf_out() at pfil_mbuf_out+0x38/frame 0xfffffe001d7da960
ip_output() at ip_output+0xb4a/frame 0xfffffe001d7daa60
ip_forward() at ip_forward+0x3c2/frame 0xfffffe001d7dab10
ip_input() at ip_input+0x6e9/frame 0xfffffe001d7dab70
netisr_dispatch_src() at netisr_dispatch_src+0x22c/frame 0xfffffe001d7dabc0
ether_demux() at ether_demux+0x149/frame 0xfffffe001d7dabf0
ether_nh_input() at ether_nh_input+0x36e/frame 0xfffffe001d7dac50
netisr_dispatch_src() at netisr_dispatch_src+0xaf/frame 0xfffffe001d7daca0
ether_input() at ether_input+0x69/frame 0xfffffe001d7dad00
iflib_rxeof() at iflib_rxeof+0xc46/frame 0xfffffe001d7dae00
_task_fn_rx() at _task_fn_rx+0x72/frame 0xfffffe001d7dae40
gtaskqueue_run_locked() at gtaskqueue_run_locked+0x14e/frame 0xfffffe001d7daec0
gtaskqueue_thread_loop() at gtaskqueue_thread_loop+0xc2/frame 0xfffffe001d7daef0
fork_exit() at fork_exit+0x7f/frame 0xfffffe001d7daf30
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe001d7daf30
--- trap 0x5965b2cb, rip = 0x526ba4d649ac9358, rsp = 0xe81fd03ea07c40f8, rbp = 0 ---
db:1:pfs>  show registers
cs                        0x20
ds                        0x3b
es                        0x3b
fs                        0x13
gs                        0x1b
ss                           0
rax                       0x12
rcx         0xffffffff81457767
rdx         0xfffffe001d7d9fd0
rbx                      0x100
rsp         0xfffffe001d7da390
rbp         0xfffffe001d7da390
rsi                       0x2d
rdi         0xffffffff82d40298  vt_conswindow+0x10
r8                           0
r9                           0
r10                          0
r11                          0
r12                          0
r13                          0
r14         0xffffffff813db3a1
r15         0xfffffe0020565720
rip         0xffffffff80d38812  kdb_enter+0x32
rflags                    0x82
kdb_enter+0x32: movq    $0,0x2344ff3(%rip)
db:1:pfs>  show pcpu
cpuid        = 0
dynamic pcpu = 0x122bf00
curthread    = 0xfffffe0020565720: pid 0 tid 100007 critnest 1 "if_io_tqg_0"
curpcb       = 0xfffffe0020565c40
fpcurthread  = none
idlethread   = 0xfffffe00205673a0: tid 100003 "idle: cpu0"
self         = 0xffffffff84210000
curpmap      = 0xffffffff83021ab0
tssp         = 0xffffffff84210384
rsp0         = 0xfffffe001d7db000
kcr3         = 0x73a43000
ucr3         = 0xffffffffffffffff
scr3         = 0x15ba88000
gs32p        = 0xffffffff84210404
ldt          = 0xffffffff84210444
tss          = 0xffffffff84210434
curvnet      = 0xfffff80001241400
db:1:pfs>  run lockinfo
db:2:lockinfo> show locks
No such command; use "help" to list available commands
db:2:lockinfo>  show alllocks
No such command; use "help" to list available commands
db:2:lockinfo>  show lockedvnods
Locked vnodes
**************************************************************************************

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address	= 0x50
fault code		= supervisor read data, page not present
instruction pointer	= 0x20:0xffffffff80fb86d7
stack pointer	        = 0x0:0xfffffe001d7da6b0
frame pointer	        = 0x0:0xfffffe001d7da770
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 0 (if_io_tqg_0)
rdi: fffff8011bf9c80e rsi: fffffe002049d82d rdx: 0000000000000000
rcx: fffffe002049d370  r8: fffffe001d7da7d0  r9: 0000000000000000
rax: 0000000000000000 rbx: fffff8015b76d3b0 rbp: fffffe001d7da770
r10: 0000000000000000 r11: fffffe002049d370 r12: fffffe002049d370
r13: 0000000000000002 r14: fffff802da989c60 r15: fffffe001d7da9f8
trap number		= 12
panic: page fault
cpuid = 0
time = 1695450285
KDB: enter: panic

net.isr.numthreads: 1
net.isr.maxprot: 16
net.isr.defaultqlimit: 256
net.isr.maxqlimit: 10240
net.isr.bindthreads: 0
net.isr.maxthreads: 1
net.isr.dispatch: hybrid

w0w

If it makes sense, I have re-configured both nodes with LAGGs to exactly match order and interface names, but it did not change anything in this behavior. So far I can't reproduce this in VMs, but one of the VMs was crashed once sometime ago when I tried other pf bug replication, unfortunately I have not saved this crash, but it was similar, fatal trap 12, referring to two exact things:
fault virtual address = 0x50
and
fault code = supervisor read data, page not present

cmcdonald

@w0w Can you try disabling pfsync?

w0w

@cmcdonald
Last time when I disabled pfsync, it stopped to crash. But I need to re-test it.

w0w

@cmcdonald
Yes, looks like the problem is limited to “Synchronize states” option.

kprovost

@w0w I've had a look at that dump, and while I think I've identified what's going wrong I do not understand how we can end up in that situation.

It'd be interesting to get a full core dump (as opposed to these text dumps). Are you up for reproducing the problem and sharing a core dump (along with the exact version you triggered the crash on, of course)?

Short version: add a device for a swap partition, ideally at least as large as system RAM. A USB stick should work. (Note you'll lose all data on the stick!)
If the USB (or other) swap device is da0 do:

gpart destroy -F da0
gpart create -s gpt da0
gpart add -t freebsd-swap da0

Add /dev/da0p1 none swap sw 0 0 to /etc/fstab.
Edit /etc/pfSense-ddb.conf and change the script kdb.enter.default to script kdb.enter.default=bt ; show registers ; dump ; reset.

Reboot.

Future panics should dump a kernel core to the swap partition, which will get saved to /var/crash on the next boot. Those files (along with an exact version number of the system this happened on) should let us dig a bit deeper.

cmcdonald

@w0w What if you restrict pfsync updates from primary to secondary only, a vice-versa...instead of bi-directional syncing?

w0w

@cmcdonald That's what I did last time
It looks like it stopped to crash, but maybe it needs further testing, not sure.
@kprovost
I posted some links with core dumps created privately

cmcdonald

@w0w disabling which sync path (primary to secondary or secondary to primary) ?

w0w

@cmcdonald
Secondary to primary.

w0w

https://redmine.pfsense.org/issues/14804

Just for reference, problem solved.