bisecting fixing commit since 4762bcd451a9e92e79d5146d3d4a5ffe2b4e0ec5
building syzkaller on 048f2d494ee4a016e2386c28bf8cccdd87896cbd
testing commit 4762bcd451a9e92e79d5146d3d4a5ffe2b4e0ec5 with gcc (GCC) 8.1.0
kernel signature: f32797e7ff45e0cbd038f160d2841c74af1462a7
run #0: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #1: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #2: OK
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing current HEAD c1141b3aab36eb0d9b2bcae4aff69e77d0554386
testing commit c1141b3aab36eb0d9b2bcae4aff69e77d0554386 with gcc (GCC) 8.1.0
kernel signature: b54cf4959d9b2915c7c3d8a257bdf2748a46a0b4
run #0: crashed: INFO: rcu detected stall in corrupted
run #1: crashed: INFO: rcu detected stall in corrupted
run #2: crashed: INFO: rcu detected stall in corrupted
run #3: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #4: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #5: crashed: INFO: rcu detected stall in corrupted
run #6: crashed: INFO: rcu detected stall in corrupted
run #7: OK
run #8: OK
run #9: OK
revisions tested: 2, total time: 37m3.708168509s (build: 16m41.130367935s, test: 19m47.032862309s)
the crash still happens on HEAD
commit msg: Linux 4.14.166
crash: INFO: rcu detected stall in corrupted
INFO: rcu_preempt detected stalls on CPUs/tasks:
	Tasks blocked on level-0 rcu_node (CPUs 0-1): P90
	(detected by 1, t=10502 jiffies, g=7718, c=7717, q=10)
kworker/u4:3    R  running task    24904    90      2 0x80000000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x780/0x1d20 kernel/sched/core.c:3384
 preempt_schedule_irq+0xb9/0x140 kernel/sched/core.c:3611
 retint_kernel+0x1b/0x2d
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline]
RIP: 0010:lock_acquire+0x1f1/0x400 kernel/locking/lockdep.c:3997
RSP: 0018:ffff8880a997fcb8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10
RAX: dffffc0000000000 RBX: ffff8880a9972200 RCX: ffff8880a9972a80
RDX: 1ffffffff0f22d39 RSI: ffff8880a9972ad0 RDI: 0000000000000282
RBP: ffff8880a997fd00 R08: ffff8880a9972af0 R09: 0000000000000000
R10: 0000000000000050 R11: ffff8880a9972200 R12: 0000000000000000
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:242 [inline]
 rcu_read_lock include/linux/rcupdate.h:629 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline]
 batadv_nc_worker+0xef/0x630 net/batman-adv/network-coding.c:726
 process_one_work+0x79e/0x16c0 kernel/workqueue.c:2114
 worker_thread+0xcc/0xee0 kernel/workqueue.c:2248
 kthread+0x338/0x400 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
kworker/u4:3    R  running task    24904    90      2 0x80000000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x780/0x1d20 kernel/sched/core.c:3384
 preempt_schedule_irq+0xb9/0x140 kernel/sched/core.c:3611
 retint_kernel+0x1b/0x2d
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline]
RIP: 0010:lock_acquire+0x1f1/0x400 kernel/locking/lockdep.c:3997
RSP: 0018:ffff8880a997fcb8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10
RAX: dffffc0000000000 RBX: ffff8880a9972200 RCX: ffff8880a9972a80
RDX: 1ffffffff0f22d39 RSI: ffff8880a9972ad0 RDI: 0000000000000282
RBP: ffff8880a997fd00 R08: ffff8880a9972af0 R09: 0000000000000000
R10: 0000000000000050 R11: ffff8880a9972200 R12: 0000000000000000
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:242 [inline]
 rcu_read_lock include/linux/rcupdate.h:629 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline]
 batadv_nc_worker+0xef/0x630 net/batman-adv/network-coding.c:726
 process_one_work+0x79e/0x16c0 kernel/workqueue.c:2114
 worker_thread+0xcc/0xee0 kernel/workqueue.c:2248
 kthread+0x338/0x400 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
rcu_preempt kthread starved for 10495 jiffies! g7718 c7717 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0 ->cpu=1
rcu_preempt     R  running task    28824     8      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x780/0x1d20 kernel/sched/core.c:3384
 schedule+0x7f/0x1b0 kernel/sched/core.c:3428
 schedule_timeout+0x40c/0xcc0 kernel/time/timer.c:1746
 rcu_gp_kthread+0xbbf/0x1e00 kernel/rcu/tree.c:2255
 kthread+0x338/0x400 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404