panic: vm_fault: fault on stack guard, addr: 0xfffff8011838c000
cpuid = 0
Trace beginning at frame 0xfffff801186de2e8
vm_fault() at vm_fault+0x12eb 0xffffffff8099ef9b 
vm_fault() at vm_fault+0x12eb 0xffffffff8099ef9b 
trap_pfault() at trap_pfault+0x9a 0xffffffff80bd52ca 
trap() at trap+0x17c 0xffffffff80bd5bcc 
calltrap() at calltrap+0x9 0xffffffff80b991fa 
--- trap 000000000000000c, rip = ffffffff80bcaeaa, rsp = fffff801186de6f0, rbp = fffff801186de758 ---
std_copyout() at std_copyout+0x15a 0xffffffff80bcaeaa 
ext2_readlink() at ext2_readlink+0x48 0xffffffff8260d418 
Debugger("panic")

CPU0 stopping CPUs: 0x0000003e
 stopped
Stopped at      Debugger+0x7c:  movb    $0,0xbdaf09(%rip)
db>