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WARNING: CPU: 1 PID: 3931 at kernel/kthread.c:87 free_kthread_struct+0xa2/0xe0 kernel/kthread.c:87
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 3931 Comm: syz-executor2 Not tainted 4.14.0-rc4-next-20171009+ #33
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 panic+0x1e4/0x41c kernel/panic.c:181
 __warn+0x1c4/0x1e0 kernel/panic.c:544
 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:free_kthread_struct+0xa2/0xe0 kernel/kthread.c:87
RSP: 0018:ffff8801db307768 EFLAGS: 00010206
RAX: 0000000080000100 RBX: ffff8801c3efdc80 RCX: 1ffff1003b660ee1
RDX: ffff8801c609a380 RSI: 0000000000000000 RDI: ffff8801c3efde08
RBP: ffff8801db307770 R08: 0000000000000000 R09: 1ffff1003b660ed4
R10: ffff8801c609a380 R11: 0000000000000002 R12: 1ffff1003b660ef0
R13: 1ffff1003b660ef4 R14: 0000000000000000 R15: ffff8801db3077e0
 free_task+0x134/0x1a0 kernel/fork.c:386
 __put_task_struct+0x229/0x3b0 kernel/fork.c:665
 put_task_struct include/linux/sched/task.h:95 [inline]
 delayed_put_task_struct+0xca/0x3d0 kernel/exit.c:180
 __rcu_reclaim kernel/rcu/rcu.h:195 [inline]
 rcu_do_batch kernel/rcu/tree.c:2691 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2945 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2912 [inline]
 rcu_process_callbacks+0xd74/0x17d0 kernel/rcu/tree.c:2929
 __do_softirq+0x29d/0xbb2 kernel/softirq.c:284
 invoke_softirq kernel/softirq.c:364 [inline]
 irq_exit+0x1d3/0x210 kernel/softirq.c:405
 exiting_irq arch/x86/include/asm/apic.h:540 [inline]
 smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1041
 apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:770
 </IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x1/0x50 kernel/kcov.c:55
RSP: 0018:ffff8801c3d47d40 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff11
RAX: 0000000000000142 RBX: 1ffff100387a8fb1 RCX: ffffc900024c7000
RDX: 0000000000010000 RSI: ffffffff83e1e2f3 RDI: ffff8801db31afac
RBP: ffff8801c3d47e50 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffffffff86e2ace0 R12: 0000000000000001
R13: 0000000000000001 R14: ffffffff853cca40 R15: ffffffff853cca50
 sock_create net/socket.c:1302 [inline]
 SYSC_socketpair net/socket.c:1374 [inline]
 SyS_socketpair+0x115/0x640 net/socket.c:1353
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x4520a9
RSP: 002b:00007f542722bc08 EFLAGS: 00000216 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 00000000004520a9
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000
R10: 000000002082c000 R11: 0000000000000216 R12: 00000000004dd792
R13: 00000000ffffffff R14: 0000000000000006 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..