bisecting fixing commit since 5692097116094a4a7045abcc1dbc172dbdc5657e
building syzkaller on d850e9d08467726cd94b6a9caaf8090c594721ba
testing commit 5692097116094a4a7045abcc1dbc172dbdc5657e with gcc (GCC) 8.1.0
kernel signature: 710e04c76463ee1842584b5298b5c2f11b45ba06669bb61ef25041a51c4deaa7
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 corrupted
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 corrupted
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
testing current HEAD dda0e2920330128e0dbdeb11c8f25031aa40b11c
testing commit dda0e2920330128e0dbdeb11c8f25031aa40b11c with gcc (GCC) 8.1.0
kernel signature: e5ddc1c4cd30f028a1118545b339f79990dcd82421eacb2a9bec860a04c97d1d
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 corrupted
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 corrupted
run #6: crashed: INFO: rcu detected stall in corrupted
run #7: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
run #8: crashed: INFO: rcu detected stall in corrupted
run #9: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl
revisions tested: 2, total time: 29m1.077651776s (build: 18m25.980477506s, test: 9m52.623307958s)
the crash still happens on HEAD
commit msg: Linux 4.19.114
crash: INFO: rcu detected stall in kvm_vcpu_ioctl
batman_adv: batadv0: Interface activated: batadv_slave_1
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: 	(detected by 1, t=10502 jiffies, g=6333, q=562)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294952768-4294942266), jiffies_till_next_fqs=1, root ->qsmask 0x0
syz-executor.2  R  running task    27160  7862   6595 0x00000800
Call Trace:
 <IRQ>
 sched_show_task.cold.87+0x2ee/0x35d kernel/sched/core.c:5338
 print_other_cpu_stall kernel/rcu/tree.c:1430 [inline]
 check_cpu_stall kernel/rcu/tree.c:1557 [inline]
 __rcu_pending kernel/rcu/tree.c:3293 [inline]
 rcu_pending kernel/rcu/tree.c:3336 [inline]
 rcu_check_callbacks.cold.81+0xa80/0xd67 kernel/rcu/tree.c:2682
 update_process_times+0x2a/0x60 kernel/time/timer.c:1638
 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:168
 tick_sched_timer+0x37/0xf0 kernel/time/tick-sched.c:1278
 __run_hrtimer kernel/time/hrtimer.c:1401 [inline]
 __hrtimer_run_queues+0x2f7/0xab0 kernel/time/hrtimer.c:1463
 hrtimer_interrupt+0x2df/0x760 kernel/time/hrtimer.c:1521
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline]
 smp_apic_timer_interrupt+0x114/0x540 arch/x86/kernel/apic/apic.c:1092
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893
 </IRQ>
RIP: 0010:vcpu_enter_guest+0xba3/0x5120 arch/x86/kvm/x86.c:7831
Code: 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 fb 40 00 00 48 83 3d 32 bf 46 07 00 0f 84 d3 31 00 00 fb 66 0f 1f 44 00 00 <bf> 01 00 00 00 e8 63 47 36 00 65 8b 05 0c ab f6 7e 85 c0 0f 84 b5
RSP: 0018:ffff88808c75f980 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffff888082aa8040 RCX: 1ffff11011775d7c
RDX: 1ffffffff10a403b RSI: ffff88808bbaebc0 RDI: ffffffff885201d8
RBP: ffff88808c75fa80 R08: ffff88808bbaebe0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88808bbae340
R13: 000000386ea1bd66 R14: ffffffe35423173d R15: ffff888082aa8070
 vcpu_run arch/x86/kvm/x86.c:7913 [inline]
 kvm_arch_vcpu_ioctl_run+0x2e9/0x1340 arch/x86/kvm/x86.c:8113
 kvm_vcpu_ioctl+0x535/0xb60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2667
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x196/0x10c0 fs/ioctl.c:688
 ksys_ioctl+0x62/0x90 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:710
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c679
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f78f61e3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f78f61e46d4 RCX: 000000000045c679
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000006
RBP: 000000000076bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000003bf R14: 00000000004c62b5 R15: 000000000076bfac
rcu: rcu_preempt kthread starved for 10502 jiffies! g6333 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: RCU grace-period kthread stack dump:
rcu_preempt     R  running task    29704    10      2 0x80000000
Call Trace:
 context_switch kernel/sched/core.c:2826 [inline]
 __schedule+0x78c/0x1c10 kernel/sched/core.c:3515
 schedule+0x7f/0x1b0 kernel/sched/core.c:3559
 schedule_timeout+0x3ab/0xda0 kernel/time/timer.c:1806
 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