syzbot

login: uvm_fault(0xfffffd807efff708, 0x8f, 0, 1) -> e
kernel: page fault trap, code=0
Stopped at      wsmuxclose+0x75:        cmpq    %r12,0x90(%r15)
ddb{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
kernel page fault
uvm_fault(0xfffffd807efff708, 0x8f, 0, 1) -> e
wsmuxclose(4500,1,2000,ffff800020b43c38) at wsmuxclose+117
end trace frame: 0xffff800020c47490, count: 0
ddb{1}> trace
wsmuxclose(4500,1,2000,ffff800020b43c38) at wsmuxclose+117
spec_close(ffff800020c474a0) at spec_close+928
VOP_CLOSE(fffffd806e6baa38,1,fffffd807f7c7d80,ffff800020b43c38) at VOP_CLOSE+112
vn_closefile(fffffd8074222010,ffff800020b43c38) at vn_closefile+352
fdrop(fffffd8074222010,ffff800020b43c38) at fdrop+225
closef(fffffd8074222010,ffff800020b43c38) at closef+297
fdrelease(ffff800020b43c38,3) at fdrelease+217
sys_close(ffff800020b43c38,ffff800020c47758,ffff800020c47740) at sys_close+174
syscall(ffff800020c477f0) at syscall+1452
Xsyscall(6,0,ffffffffffffff0b,0,1,59d8b1c90d8) at Xsyscall+296
end of kernel
end trace frame: 0x59fa6def860, count: -10
ddb{1}> show registers
rdi                                0
rsi                                0
rbp             18446603336770941984
rbx                                0
rdx             18446744071594843605    substchar+94256
rcx             18446741324976795872
rax                                0
r8              18446744071585836581    setrunnable+149
r9                                 5
r10             16199311595794374609
r11               649327871048614550
r12             18446603336221355264
r13                                0
r14             18446603336221355344
r15             18446744073709551615
rip             18446744071593530949    wsmuxclose+117
cs                                 8
rflags                         66118    __ALIGN_SIZE+62022
rsp             18446603336770941920
ss                                16
wsmuxclose+117: cmpq    %r12,144(%r15)
ddb{1}> show proc
PROC (syz-executor.1) pid=177586 stat=onproc
    flags process=0 proc=4000000<THREAD>
    pri=0, usrpri=86, nice=20
    forw=0xffffffffffffffff, list=0xffff800020b24260,0xffffffff8230d660
    process=0xffff800020b44010 user=0xffff800020c42000, vmspace=0xfffffd807efff708
    estcpu=36, cpticks=0, pctcpu=0.0
    user=0, sys=0, intr=0
ddb{1}>