bisecting fixing commit since a083db76118d20d070794ecf79af17843406c3f6 building syzkaller on c88c7b75a4e022b758f4b0f1bf3db8ebb2fb25e6 testing commit a083db76118d20d070794ecf79af17843406c3f6 with gcc (GCC) 8.1.0 kernel signature: d07a97f1b6a6c4b649f1f9b5e64b708a2b6d29fc436dbec32dcdea2ef950400f 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 kvm_vcpu_ioctl run #7: crashed: INFO: rcu detected stall in corrupted 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 3fc898571b974f9a05e4e5c1fe17b18548207091 testing commit 3fc898571b974f9a05e4e5c1fe17b18548207091 with gcc (GCC) 8.1.0 kernel signature: 37656dbcccf99f7d192933216960942564cabe1d60c241f6d09ba02fba045c44 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 corrupted 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 revisions tested: 2, total time: 29m10.633397112s (build: 17m44.838921245s, test: 10m52.183709845s) the crash still happens on HEAD commit msg: Linux 4.19.128 crash: INFO: rcu detected stall in corrupted 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. 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): P107 rcu: (detected by 0, t=10502 jiffies, g=7621, q=370) kworker/u4:2 R running task 24648 107 2 0x80000000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 preempt_schedule_irq+0x87/0x110 kernel/sched/core.c:3742 retint_kernel+0x1b/0x2d RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:lock_acquire+0x1f1/0x3d0 kernel/locking/lockdep.c:3910 Code: 00 00 00 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 aa 01 00 00 48 83 3d 73 e6 06 07 00 0f 84 31 01 00 00 48 8b 7d c8 57 9d <0f> 1f 44 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 65 8b RSP: 0018:ffff8880a9617b58 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffff8880a96084c0 RCX: 1ffff110152c11bc RDX: 1ffffffff10a4069 RSI: 0000000000000000 RDI: 0000000000000286 RBP: ffff8880a9617ba0 R08: ffff8880a9608de0 R09: 0000000000000003 R10: ffff8880a9608dc0 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:242 [inline] rcu_read_lock include/linux/rcupdate.h:627 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:940 [inline] batadv_iv_ogm_schedule_buff+0x4ff/0xfe0 net/batman-adv/bat_iv_ogm.c:1006 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:1050 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x2a7/0x830 net/batman-adv/bat_iv_ogm.c:1869 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/u4:2 R running task 24648 107 2 0x80000000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 preempt_schedule_irq+0x87/0x110 kernel/sched/core.c:3742 retint_kernel+0x1b/0x2d RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:lock_acquire+0x1f1/0x3d0 kernel/locking/lockdep.c:3910 Code: 00 00 00 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 aa 01 00 00 48 83 3d 73 e6 06 07 00 0f 84 31 01 00 00 48 8b 7d c8 57 9d <0f> 1f 44 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 65 8b RSP: 0018:ffff8880a9617b58 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffff8880a96084c0 RCX: 1ffff110152c11bc RDX: 1ffffffff10a4069 RSI: 0000000000000000 RDI: 0000000000000286 RBP: ffff8880a9617ba0 R08: ffff8880a9608de0 R09: 0000000000000003 R10: ffff8880a9608dc0 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:242 [inline] rcu_read_lock include/linux/rcupdate.h:627 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:940 [inline] batadv_iv_ogm_schedule_buff+0x4ff/0xfe0 net/batman-adv/bat_iv_ogm.c:1006 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:1050 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x2a7/0x830 net/batman-adv/bat_iv_ogm.c:1869 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 10492 jiffies! g7621 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29208 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