Hello,

syzkaller hit the following crash on  
8fd0520d9cec0896d48d3921bc642a9ee81eae0c
git://git.cmpxchg.org/linux-mmots.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


WARNING: CPU: 1 PID: 24353 at kernel/futex.c:818 get_pi_state+0x15b/0x190  
kernel/futex.c:818
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 24353 Comm: syzkaller121915 Not tainted 4.14.0-rc2-mm1+ #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:16 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:52
  panic+0x1e4/0x417 kernel/panic.c:181
  __warn+0x1c4/0x1d9 kernel/panic.c:542
  report_bug+0x211/0x2d0 lib/bug.c:183
  fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:178
  do_trap_no_signal arch/x86/kernel/traps.c:212 [inline]
  do_trap+0x260/0x390 arch/x86/kernel/traps.c:261
  do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:298
  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:311
  invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:905
RIP: 0010:get_pi_state+0x15b/0x190 kernel/futex.c:818
RSP: 0018:ffff8801bf2a77a8 EFLAGS: 00010097
RAX: ffff8801cb2d05c0 RBX: 0000000000000000 RCX: 1ffff10037e54efa
RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffff8801d892cd40
RBP: ffff8801bf2a7838 R08: ffff8801cb2d1880 R09: 1ffff10037e54edf
R10: ffff8801cb2d05c0 R11: 0000000000000002 R12: 1ffff10037e54ef6
R13: ffff8801d892cd40 R14: 1ffff10037e54efa R15: ffff8801d892ce00
  exit_pi_state_list+0x556/0x7a0 kernel/futex.c:932
  mm_release+0x46d/0x590 kernel/fork.c:1191
  exit_mm kernel/exit.c:499 [inline]
  do_exit+0x481/0x1b00 kernel/exit.c:852
  SYSC_exit kernel/exit.c:937 [inline]
  SyS_exit+0x22/0x30 kernel/exit.c:935
  entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x40337e
RSP: 002b:00007fdd99af2d20 EFLAGS: 00000246 ORIG_RAX: 000000000000003c
RAX: ffffffffffffffda RBX: 00007fdd99af3700 RCX: 000000000040337e
RDX: 000000000000003c RSI: 00000000007fb000 RDI: 0000000000000000
RBP: 0000000000000086 R08: 0000000020048000 R09: 0000000000000000
R10: 000000002000b000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcfc38d0bf R14: 00007fdd99af39c0 R15: 0000000000000000


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzkaller@googlegroups.com.

syzbot will keep track of this bug report.
Once a fix for this bug is committed, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug  
report.