bisecting fixing commit since 5692097116094a4a7045abcc1dbc172dbdc5657e
building syzkaller on d850e9d08467726cd94b6a9caaf8090c594721ba
testing commit 5692097116094a4a7045abcc1dbc172dbdc5657e with gcc (GCC) 8.1.0
kernel signature: 3cdf82826a97e5ec834d21775f4854f425753faa4593fcb7179239e504d8a341
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 kvm_vcpu_ioctl
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 kvm_vcpu_ioctl
run #6: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #7: crashed: INFO: rcu detected stall in corrupted
run #8: crashed: INFO: rcu detected stall in corrupted
run #9: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
testing current HEAD 13af6c74b14a883366e7702c40c52ff548096e7f
testing commit 13af6c74b14a883366e7702c40c52ff548096e7f with gcc (GCC) 8.1.0
kernel signature: e7c02149e81b057ab0878dedc2cd8ce09d3ec0486ab153b34f9cc41ef5eede2b
run #0: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #1: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #2: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #3: crashed: INFO: rcu detected stall in corrupted
run #4: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #5: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #6: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #7: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #8: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #9: crashed: INFO: rcu detected stall in corrupted
revisions tested: 2, total time: 29m41.30339986s (build: 18m27.872110984s, test: 9m38.390546334s)
the crash still happens on HEAD
commit msg: Linux 4.19.136
crash: INFO: rcu detected stall in corrupted
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
kvm: emulating exchange as write
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P404
rcu: 	(detected by 0, t=10503 jiffies, g=6493, q=56)
kworker/u4:3    R  running task    25304   404      2 0x80000000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 context_switch kernel/sched/core.c:2828 [inline]
 __schedule+0x78c/0x1c10 kernel/sched/core.c:3517
 preempt_schedule_notrace+0x70/0x140 kernel/sched/core.c:3715
 ___preempt_schedule_notrace+0x16/0x2d
 rcu_is_watching+0x23/0x30 kernel/rcu/tree.c:1026
 rcu_read_lock include/linux/rcupdate.h:628 [inline]
 batadv_nc_process_nc_paths.part.15+0x20c/0x2d0 net/batman-adv/network-coding.c:698
 batadv_nc_process_nc_paths net/batman-adv/network-coding.c:690 [inline]
 batadv_nc_worker+0x43d/0x630 net/batman-adv/network-coding.c:739
 process_one_work+0x830/0x1670 kernel/workqueue.c:2155
 worker_thread+0x85/0xb60 kernel/workqueue.c:2298
 kthread+0x324/0x3e0 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
kworker/u4:3    R  running task    25304   404      2 0x80000000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 context_switch kernel/sched/core.c:2828 [inline]
 __schedule+0x78c/0x1c10 kernel/sched/core.c:3517
 preempt_schedule_notrace+0x70/0x140 kernel/sched/core.c:3715
 ___preempt_schedule_notrace+0x16/0x2d
 rcu_is_watching+0x23/0x30 kernel/rcu/tree.c:1026
 rcu_read_lock include/linux/rcupdate.h:628 [inline]
 batadv_nc_process_nc_paths.part.15+0x20c/0x2d0 net/batman-adv/network-coding.c:698
 batadv_nc_process_nc_paths net/batman-adv/network-coding.c:690 [inline]
 batadv_nc_worker+0x43d/0x630 net/batman-adv/network-coding.c:739
 process_one_work+0x830/0x1670 kernel/workqueue.c:2155
 worker_thread+0x85/0xb60 kernel/workqueue.c:2298
 kthread+0x324/0x3e0 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
rcu: rcu_preempt kthread starved for 10510 jiffies! g6493 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29704    10      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2828 [inline]
 __schedule+0x78c/0x1c10 kernel/sched/core.c:3517
 schedule+0x7f/0x1b0 kernel/sched/core.c:3561
 schedule_timeout+0x3ab/0xe00 kernel/time/timer.c:1817
 rcu_gp_kthread+0xce6/0x23d0 kernel/rcu/tree.c:2202
 kthread+0x324/0x3e0 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415