bisecting fixing commit since 94f2630b18975bb56eee5d1a36371db967643479 building syzkaller on 2274ad39c8bee8efda31dc31ec8933d5624e8fe4 testing commit 94f2630b18975bb56eee5d1a36371db967643479 with gcc (GCC) 8.1.0 kernel signature: 364b2d8680683306a5d9d58dfc2ab094adbdcc988c592ab3f0de7f0435add7d0 run #0: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl 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 corrupted 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 corrupted run #8: crashed: INFO: rcu detected stall in corrupted run #9: boot failed: can't ssh into the instance testing current HEAD d3dca69085e94e52a1d61a34b8e5f73a9f3d7eed testing commit d3dca69085e94e52a1d61a34b8e5f73a9f3d7eed with gcc (GCC) 8.1.0 kernel signature: 3a49842df479edcf7880524f79605678222fffded4a91483ce7de6f82d976d7e 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 corrupted 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 kvm_vcpu_ioctl run #9: boot failed: can't ssh into the instance revisions tested: 2, total time: 36m26.535839079s (build: 12m43.988803537s, test: 22m49.78279297s) the crash still happens on HEAD commit msg: Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux crash: INFO: rcu detected stall in kvm_vcpu_ioctl rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=8737, q=197) rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4294956148-4294945647), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.4 R running task 27048 8913 8866 0x00000000 Call Trace: sched_show_task.cold.100+0x2ee/0x35d kernel/sched/core.c:5952 print_other_cpu_stall kernel/rcu/tree_stall.h:430 [inline] check_cpu_stall kernel/rcu/tree_stall.h:558 [inline] rcu_pending kernel/rcu/tree.c:3030 [inline] rcu_sched_clock_irq.cold.87+0xb55/0xc86 kernel/rcu/tree.c:2276 update_process_times+0x23/0x50 kernel/time/timer.c:1726 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:171 tick_sched_timer+0x43/0x100 kernel/time/tick-sched.c:1314 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x32f/0xb50 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x2df/0x760 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline] smp_apic_timer_interrupt+0x163/0x5f0 arch/x86/kernel/apic/apic.c:1144 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:kvm_after_interrupt arch/x86/kvm/x86.h:348 [inline] RIP: 0010:handle_external_interrupt_irqoff+0x18a/0x200 arch/x86/kvm/vmx/vmx.c:6295 Code: e0 a6 a3 87 e8 a7 da 47 02 65 4c 89 25 c7 d7 ea 7e 48 c1 e3 20 4c 09 eb 4c 09 f3 48 89 e0 48 83 e4 f0 6a 18 50 9c 6a 10 ff d3 <48> c7 c7 e0 a6 a3 87 e8 7a da 47 02 65 48 c7 05 96 d7 ea 7e 00 00 RSP: 0018:ffffc90002d5fa68 EFLAGS: 00000086 ORIG_RAX: ffffffffffffff13 RAX: ffffc90002d5fa68 RBX: ffffffff87601710 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000001 RDI: ffffffff87a3a6e0 RBP: ffffc90002d5fa88 R08: ffffed101211a302 R09: ffffed101211a302 R10: ffffed101211a301 R11: ffff8880908d180f R12: ffff8880796a0080 R13: 0000000087600000 R14: 0000000000001710 R15: ffff8880796a0080 vmx_handle_exit_irqoff+0x1e9/0x310 arch/x86/kvm/vmx/vmx.c:6305 vcpu_enter_guest arch/x86/kvm/x86.c:8405 [inline] vcpu_run arch/x86/kvm/x86.c:8513 [inline] kvm_arch_vcpu_ioctl_run+0x2bbd/0x5e50 arch/x86/kvm/x86.c:8735 kvm_vcpu_ioctl+0x507/0xac0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2932 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0xc1/0x110 fs/ioctl.c:763 __do_sys_ioctl fs/ioctl.c:772 [inline] __se_sys_ioctl fs/ioctl.c:770 [inline] __x64_sys_ioctl+0x6e/0xb0 fs/ioctl.c:770 do_syscall_64+0xca/0x630 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b399 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:00007f09ca4ccc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f09ca4cd6d4 RCX: 000000000045b399 RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000009 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000003ba R14: 00000000004c4f9c R15: 000000000075bf2c rcu: rcu_preempt kthread starved for 10539 jiffies! g8737 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29360 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3380 [inline] __schedule+0x8a9/0x1970 kernel/sched/core.c:4080 schedule+0xc3/0x2b0 kernel/sched/core.c:4154 schedule_timeout+0x38b/0xad0 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline] rcu_gp_kthread+0x9f2/0x1890 kernel/rcu/tree.c:1818 kthread+0x331/0x3f0 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 sched: RT throttling activated