bisecting fixing commit since f8f65382c98a28e3c2b20df9dd4231dca5a11682 building syzkaller on 6b5120a46407f0462e664e15fed3eae5da951c75 testing commit f8f65382c98a28e3c2b20df9dd4231dca5a11682 with gcc (GCC) 8.1.0 kernel signature: 12fa5c51d19b9c141819175cc4eb0212910edf7965fe9ae2e5ae05836b2b893d 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 corrupted 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 kvm_vcpu_ioctl testing current HEAD c578ddb39e565139897124e74e5a43e56538cb33 testing commit c578ddb39e565139897124e74e5a43e56538cb33 with gcc (GCC) 8.1.0 kernel signature: 4bc19994f49a528aa84acdd287631315b67da92966f2b2d2d194ca706b4eb7e8 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 kvm_vcpu_ioctl run #4: crashed: INFO: rcu detected stall in corrupted 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 kvm_vcpu_ioctl revisions tested: 2, total time: 23m31.633933216s (build: 11m50.173451684s, test: 10m51.67025972s) the crash still happens on HEAD commit msg: Merge tag 'linux-kselftest-5.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest crash: INFO: rcu detected stall in kvm_vcpu_ioctl 8021q: adding VLAN 0 to HW filter on device team0 L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details. hrtimer: interrupt took 35647 ns rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=5601, q=576) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294955469-4294944966), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor2 R running task 27392 7900 5623 0x00000800 Call Trace: sched_show_task.cold.103+0x2ee/0x35d kernel/sched/core.c:5961 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:3225 [inline] rcu_sched_clock_irq.cold.87+0xaa3/0xc50 kernel/rcu/tree.c:2296 update_process_times+0x23/0x50 kernel/time/timer.c:1727 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:176 tick_sched_timer+0x43/0x100 kernel/time/tick-sched.c:1320 __run_hrtimer kernel/time/hrtimer.c:1520 [inline] __hrtimer_run_queues+0x52a/0xc10 kernel/time/hrtimer.c:1584 hrtimer_interrupt+0x2df/0x760 kernel/time/hrtimer.c:1646 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline] smp_apic_timer_interrupt+0x16f/0x600 arch/x86/kernel/apic/apic.c:1138 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:759 [inline] RIP: 0010:lock_acquire+0x291/0x9e0 kernel/locking/lockdep.c:4937 Code: ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 64 06 00 00 48 83 3d 2e 6a 21 07 00 0f 84 d3 04 00 00 48 8b bd 48 ff ff ff 57 9d <0f> 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 01 c3 c7 03 00 00 RSP: 0018:ffff8881b5f77628 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: 1ffff11036beeec9 RCX: 1ffff11036beeeae RDX: 1ffffffff10e98fc RSI: 0000000000000001 RDI: 0000000000000282 RBP: ffff8881b5f776f0 R08: fffffbfff1401fe4 R09: fffffbfff1401fe4 R10: ffffffff8a00ff1f R11: fffffbfff1401fe3 R12: ffff8881c4c88600 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:353 [inline] kvm_mmu_unprotect_page+0x9d/0x440 arch/x86/kvm/mmu/mmu.c:2886 retry_instruction arch/x86/kvm/x86.c:6632 [inline] x86_emulate_instruction+0x4c1/0x18a0 arch/x86/kvm/x86.c:6859 kvm_mmu_page_fault+0x259/0x1010 arch/x86/kvm/mmu/mmu.c:5495 handle_ept_violation+0x194/0x3d0 arch/x86/kvm/vmx/vmx.c:5196 vmx_handle_exit+0x231/0x1470 arch/x86/kvm/vmx/vmx.c:5980 vcpu_enter_guest arch/x86/kvm/x86.c:8498 [inline] vcpu_run arch/x86/kvm/x86.c:8561 [inline] kvm_arch_vcpu_ioctl_run+0x2b36/0x56c0 arch/x86/kvm/x86.c:8783 kvm_vcpu_ioctl+0x452/0xb90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3138 vfs_ioctl fs/ioctl.c:47 [inline] ksys_ioctl+0xc4/0x120 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+0xd0/0x630 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x4571e9 Code: fd b4 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 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f3076d36c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f3076d376d4 RCX: 00000000004571e9 RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000006 RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004cf7d0 R14: 00000000004c5a59 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10544 jiffies! g5601 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29408 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x895/0x1960 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 schedule_timeout+0x2bd/0x710 kernel/time/timer.c:1898 rcu_gp_fqs_loop kernel/rcu/tree.c:1674 [inline] rcu_gp_kthread+0x9da/0x1a40 kernel/rcu/tree.c:1836 kthread+0x357/0x420 kernel/kthread.c:268 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352