kernel panic at kern/arch/x86/trap.c:540, from core 2: Double fault!  Check the kernel stack pointer; you likely ran off the end of the stack.
HW TRAP frame at 0xfffffff000023f40 on core 2
  rax  0x0000000080000001
  rbx  0xfffffff0000c4d30
  rcx  0x00000000000003d4
  rdx  0x000000000000186a
  rbp  0xfffffff0000c4cc8
  rsi  0x0000000000000780
  rdi  0xffffffffc210eb30
  r8   0xffff8000000b8fa0
  r9   0x0000000000000f00
  r10  0xffff8000000b8f00
  r11  0xffff8000000b8ec0
  r12  0xffffffffc20babe8
  r13  0x0000000000000800
  r14  0xfffffff0000c4e00
  r15  0xffff800002179b80
  trap 0x00000008 Double Fault
  gsbs 0xffffffffc8667ec0
  fsbs 0x0000000000000000
  err  0x--------00000000
  rip  0xffffffffc2048014
  cs   0x------------0008
  flag 0x0000000000010202
  rsp  0xfffffff0000c4cc8
  ss   0x------------0010
Backtrace of kernel context on Core 2:
#01 [<     [inline]     >] in spin_unlock_irqsave.part.2 at include/atomic.h:302
#01 [<0xffffffffc2048014>] in print_unlock.part.2 at src/printf.c:37
#02 [<     [inline]     >] in print_unlock at src/printf.c:34
#02 [<0xffffffffc2048288>] in vcprintf at src/printf.c:98
#03 [<0xffffffffc20482e3>] in cprintf at src/printf.c:112
#04 [<0xffffffffc20075f1>] in send_event at src/event.c:408
#05 [<0xffffffffc2056025>] in sys_send_event at src/syscall.c:1520
#06 [<0xffffffffc2059439>] in syscall at src/syscall.c:2528
#07 [<0xffffffffc2059604>] in run_local_syscall at src/syscall.c:2563
#08 [<0xffffffffc2059b39>] in prep_syscalls at src/syscall.c:2583
#09 [<0xffffffffc20ab38a>] in sysenter_callwrapper at arch/x86/trap.c:854