Unread portion of the kernel message buffer:
<6>pid 48502 (chrome), uid 1001: exited on signal 11 (core dumped)


Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0x100000021
fault code              = supervisor read data, page not present
...
(kgdb) bt
#0  doadump (textdump=1) at pcpu.h:223
#1  0xffffffff8063d9fd in kern_reboot (howto=260) at
/usr/src/sys/kern/kern_shutdown.c:445
#2  0xffffffff8063df3f in panic (fmt=<value optimized out>) at
/usr/src/sys/kern/kern_shutdown.c:621
#3  0xffffffff80861f4f in trap_fatal (frame=<value optimized out>, eva=<value
optimized out>) at /usr/src/sys/amd64/amd64/trap.c:866
#4  0xffffffff8086229c in trap_pfault (frame=0xfffffe01dd5d89e0, usermode=<value
optimized out>) at /usr/src/sys/amd64/amd64/trap.c:677
#5  0xffffffff808618be in trap (frame=0xfffffe01dd5d89e0) at
/usr/src/sys/amd64/amd64/trap.c:426
#6  0xffffffff808623f7 in trap_check (frame=<value optimized out>) at
/usr/src/sys/amd64/amd64/trap.c:620
#7  0xffffffff80845122 in calltrap () at /usr/src/sys/amd64/amd64/exception.S:231
#8  0xffffffff806d6668 in unp_gc (arg=0x10, pending=32) at
/usr/src/sys/kern/uipc_usrreq.c:2152
#9  0xffffffff8068f465 in taskqueue_run_locked (queue=0xfffff80012294600) at
/usr/src/sys/kern/subr_taskqueue.c:371
#10 0xffffffff80690258 in taskqueue_thread_loop (arg=<value optimized out>) at
/usr/src/sys/kern/subr_taskqueue.c:642
#11 0xffffffff80605a1a in fork_exit (callout=0xffffffff80690190
<taskqueue_thread_loop>, arg=0xffffffff80ee17c0, frame=0xfffffe01dd5d8c00) at
/usr/src/sys/kern/kern_fork.c:977
#12 0xffffffff8084565e in fork_trampoline () at
/usr/src/sys/amd64/amd64/exception.S:605

(kgdb) fr 8
#8  0xffffffff806d6668 in unp_gc (arg=0x10, pending=32) at
/usr/src/sys/kern/uipc_usrreq.c:2152
2152                    fp = fdep[i]->fde_file;
(kgdb) list
2147            struct unpcb *unp;
2148            struct file *fp;
2149            int i;
2150
2151            for (i = 0; i < fdcount; i++) {
2152                    fp = fdep[i]->fde_file;
2153                    if ((unp = fptounp(fp)) == NULL)
2154                            continue;
2155                    if (unp->unp_gcflag & UNPGC_REF)
2156                            continue;

(kgdb) disassemble
...
0xffffffff806d6660 <unp_gc+672>:        mov    0x10(%rdx,%rax,8),%rcx
0xffffffff806d6665 <unp_gc+677>:        mov    (%rcx),%rcx
0xffffffff806d6668 <unp_gc+680>:        cmpw   $0x2,0x20(%rcx)
0xffffffff806d666d <unp_gc+685>:        jne    0xffffffff806d66b0 <unp_gc+752>
0xffffffff806d666f <unp_gc+687>:        mov    (%rcx),%rcx
0xffffffff806d6672 <unp_gc+690>:        test   %rcx,%rcx
0xffffffff806d6675 <unp_gc+693>:        je     0xffffffff806d66b0 <unp_gc+752>
0xffffffff806d6677 <unp_gc+695>:        mov    0x20(%rcx),%rbx
0xffffffff806d667b <unp_gc+699>:        cmp    %r14,0x8(%rbx)
0xffffffff806d667f <unp_gc+703>:        jne    0xffffffff806d66b0 <unp_gc+752>
0xffffffff806d6681 <unp_gc+705>:        mov    0x10(%rcx),%r9
0xffffffff806d6685 <unp_gc+709>:        test   %r9,%r9
0xffffffff806d6688 <unp_gc+712>:        je     0xffffffff806d66b0 <unp_gc+752>
0xffffffff806d668a <unp_gc+714>:        movzwl 0x6a(%r9),%r10d
0xffffffff806d668f <unp_gc+719>:        test   $0x1,%r10b
0xffffffff806d6693 <unp_gc+723>:        jne    0xffffffff806d66b0 <unp_gc+752>
0xffffffff806d6695 <unp_gc+725>:        and    $0xfffc,%r10d
0xffffffff806d669c <unp_gc+732>:        or     $0x1,%r10d
0xffffffff806d66a0 <unp_gc+736>:        mov    %r10w,0x6a(%r9)
0xffffffff806d66a5 <unp_gc+741>:        incl   0xffffffff80e45604
0xffffffff806d66ac <unp_gc+748>:        nopl   0x0(%rax)
0xffffffff806d66b0 <unp_gc+752>:        inc    %rax
0xffffffff806d66b3 <unp_gc+755>:        cmp    %r15d,%eax
0xffffffff806d66b6 <unp_gc+758>:        jl     0xffffffff806d6660 <unp_gc+672>
...

(kgdb) i reg
rax            0x1      1
rbx            0xfffff800358713c0       -8795194977344
rcx            0x100000001      4294967297
rdx            0xfffff8006d327420       -8794260999136
rsi            0x20     32
rdi            0x10     16
rbp            0xfffffe01dd5d8b20       0xfffffe01dd5d8b20
rsp            0xfffffe01dd5d8aa0       0xfffffe01dd5d8aa0
r8             0xfffff8006d327400       -8794260999168
r9             0xffffffff809c07de       -2137258018
r10            0xfffff80012294630       -8795788327376
r11            0xfffff8006d327400       -8794260999168
r12            0xfffff801e7420000       -8787918192640
r13            0x1fffffff8      8589934584
r14            0xffffffff80c535a8       -2134559320
r15            0x2      2
rip            0xffffffff806d6668       0xffffffff806d6668 <unp_gc+680>
eflags         0x10297  66199
....

(kgdb) p (struct filedescent**)(0xfffff8006d327420 + 0x10)
$8 = (struct filedescent **) 0xfffff8006d327430
(kgdb) p $8[0]
$9 = (struct filedescent *) 0xfffff800499a9d00
(kgdb) p $8[1]
$10 = (struct filedescent *) 0xfffff800499a9d30
(kgdb) p *$9
$11 = {fde_file = 0xfffff8016ccf7cf0, fde_caps = {fc_rights = {cr_rights = {0,
0}}, fc_ioctls = 0x1, fc_nioctls = 0, fc_fcntls = 0}, fde_flags = 0 '\0'}
(kgdb) p *$10
$12 = {fde_file = 0x100000001, fde_caps = {fc_rights = {cr_rights = {0, 0}},
fc_ioctls = 0x0, fc_nioctls = 0, fc_fcntls = 0}, fde_flags = 0 '\0'}
(kgdb) p $11.fde_file
$13 = (struct file *) 0xfffff8016ccf7cf0
(kgdb) p *$11.fde_file
$14 = {f_data = 0xfffff8002c001000, f_ops = 0xfffff801d391b588, f_cred =
0x17f0b, f_vnode = 0xffffffff809440d1, f_type = 0, f_vnread_flags = 625, f_flag
= 0, f_count = 0, f_seqcount = 0, f_nextoff = 1, f_vnun = {
    fvn_cdevpriv = 0xffffffff809440dd, fvn_advice = 0xffffffff809440dd},
f_offset = 40960000, f_label = 0x0}
(kgdb) p *$14.f_ops
$15 = {fo_read = 0xffffffff8098daa8 <g_part_null_methods+216>, fo_write =
0xffffffff80bfab00 <zfs_vnodeops>, fo_truncate = 0xfffff8016ccf7cf0, fo_ioctl =
0xfffff8001aeb1990, fo_poll = 0, fo_kqfilter = 0xfffff801d391bb30,
  fo_stat = 0, fo_close = 0, fo_chmod = 0, fo_chown = 0, fo_sendfile = 0,
fo_seek = 0xfffff801d391b5d8, fo_flags = 0}
(kgdb) p *$14.f_vnode
$16 = {v_tag = 0x6f6c5f7a3e2d707a <Address 0x6f6c5f7a3e2d707a out of bounds>,
v_op = 0x3e2d707a26006b63, v_data = 0x746e657261705f7a, ...}