bisecting fixing commit since 5692097116094a4a7045abcc1dbc172dbdc5657e building syzkaller on d850e9d08467726cd94b6a9caaf8090c594721ba testing commit 5692097116094a4a7045abcc1dbc172dbdc5657e with gcc (GCC) 8.1.0 kernel signature: 132a2aca5a30a9998ec63e7c7359900ebae46d106d12315bc8185fabebc332d9 run #0: crashed: BUG: workqueue lockup 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 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 corrupted run #9: crashed: INFO: rcu detected stall in kvm_vcpu_ioctl testing current HEAD daefdc9eb24bfa11ab77a4b2a9c3923f1051fe0b testing commit daefdc9eb24bfa11ab77a4b2a9c3923f1051fe0b with gcc (GCC) 8.1.0 kernel signature: 9a2ccdf2533b2b2dab906303e9355fea07a121dde3657c0edca938cd8cd5d7f9 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 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 corrupted 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: 37m1.93687699s (build: 26m19.751191566s, test: 9m8.733306956s) the crash still happens on HEAD commit msg: Linux 4.19.161 crash: INFO: rcu detected stall in corrupted batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5950 rcu: (detected by 0, t=10503 jiffies, g=4909, q=199) syz-executor.4 R running task 23832 5950 5946 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 preempt_schedule_common+0x1f/0xe0 kernel/sched/core.c:3641 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3667 ___preempt_schedule+0x16/0x18 vprintk_emit+0x1ab/0x540 kernel/printk/printk.c:1966 vprintk_default+0x1a/0x20 kernel/printk/printk.c:2007 vprintk_func+0x49/0x12c kernel/printk/printk_safe.c:397 printk+0x9a/0xc0 kernel/printk/printk.c:2040 batadv_check_known_mac_addr.cold.21+0x23/0x30 net/batman-adv/hard-interface.c:529 batadv_hard_if_event+0x212/0x10d0 net/batman-adv/hard-interface.c:1065 notifier_call_chain+0x8a/0x160 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x11/0x20 kernel/notifier.c:401 call_netdevice_notifiers_info+0x28/0x60 net/core/dev.c:1744 call_netdevice_notifiers net/core/dev.c:1762 [inline] dev_set_mac_address+0x1de/0x320 net/core/dev.c:7904 do_setlink+0x5b9/0x2e10 net/core/rtnetlink.c:2404 rtnl_newlink+0xa1d/0x1320 net/core/rtnetlink.c:3077 rtnetlink_rcv_msg+0x34f/0x8f0 net/core/rtnetlink.c:4778 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2455 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4796 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x443/0x650 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x765/0xc40 net/netlink/af_netlink.c:1909 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:632 __sys_sendto+0x1f2/0x2e0 net/socket.c:1787 __do_sys_sendto net/socket.c:1799 [inline] __se_sys_sendto net/socket.c:1795 [inline] __x64_sys_sendto+0xdc/0x1a0 net/socket.c:1795 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x416373 Code: ff 0f 83 b0 19 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d 1d 21 87 00 00 75 17 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 81 19 00 00 c3 48 83 ec 08 e8 87 fa ff ff RSP: 002b:00007ffc30e5af78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000c82200 RCX: 0000000000416373 RDX: 000000000000002c RSI: 0000000000c82250 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffc30e5af80 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000c82250 R15: 0000000000000003 syz-executor.4 R running task 23832 5950 5946 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3517 preempt_schedule_common+0x1f/0xe0 kernel/sched/core.c:3641 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3667 ___preempt_schedule+0x16/0x18 vprintk_emit+0x1ab/0x540 kernel/printk/printk.c:1966 vprintk_default+0x1a/0x20 kernel/printk/printk.c:2007 vprintk_func+0x49/0x12c kernel/printk/printk_safe.c:397 printk+0x9a/0xc0 kernel/printk/printk.c:2040 batadv_check_known_mac_addr.cold.21+0x23/0x30 net/batman-adv/hard-interface.c:529 batadv_hard_if_event+0x212/0x10d0 net/batman-adv/hard-interface.c:1065 notifier_call_chain+0x8a/0x160 kernel/notifier.c:93 __raw_notifier_call_chain kernel/notifier.c:394 [inline] raw_notifier_call_chain+0x11/0x20 kernel/notifier.c:401 call_netdevice_notifiers_info+0x28/0x60 net/core/dev.c:1744 call_netdevice_notifiers net/core/dev.c:1762 [inline] dev_set_mac_address+0x1de/0x320 net/core/dev.c:7904 do_setlink+0x5b9/0x2e10 net/core/rtnetlink.c:2404 rtnl_newlink+0xa1d/0x1320 net/core/rtnetlink.c:3077 rtnetlink_rcv_msg+0x34f/0x8f0 net/core/rtnetlink.c:4778 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2455 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4796 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x443/0x650 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x765/0xc40 net/netlink/af_netlink.c:1909 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:632 __sys_sendto+0x1f2/0x2e0 net/socket.c:1787 __do_sys_sendto net/socket.c:1799 [inline] __se_sys_sendto net/socket.c:1795 [inline] __x64_sys_sendto+0xdc/0x1a0 net/socket.c:1795 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x416373 Code: ff 0f 83 b0 19 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 83 3d 1d 21 87 00 00 75 17 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 81 19 00 00 c3 48 83 ec 08 e8 87 fa ff ff RSP: 002b:00007ffc30e5af78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000c82200 RCX: 0000000000416373 RDX: 000000000000002c RSI: 0000000000c82250 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffc30e5af80 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000c82250 R15: 0000000000000003 rcu: rcu_preempt kthread starved for 10572 jiffies! g4909 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29208 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:1818 rcu_gp_kthread+0xce6/0x23d0 kernel/rcu/tree.c:2202 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 sched: RT throttling activated