bisecting fixing commit since f6d5cb9e2c06f7d583dd9f4f7cca21d13d78c32a building syzkaller on abf9ba4fc75d9b29af15625d44dcfc1360fad3b7 testing commit f6d5cb9e2c06f7d583dd9f4f7cca21d13d78c32a compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: fa11b25640e2ae922f02912ba0a55dc305b28fa4dafc337d320bad0eb6d1a0df all runs: crashed: INFO: task hung in rtnl_lock testing current HEAD 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 testing commit 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: cab0e31b85f4906e240a449a80d3d237d8dca69189267c59fb5ec923356f814a all runs: crashed: INFO: task hung in rtnl_lock revisions tested: 2, total time: 41m42.428855306s (build: 26m26.013443556s, test: 14m37.802162572s) the crash still happens on HEAD commit msg: Linux 4.19.204 crash: INFO: task hung in rtnl_lock Bluetooth: hci3: command 0x0406 tx timeout Bluetooth: hci1: command 0x0406 tx timeout Bluetooth: hci0: command 0x0406 tx timeout Bluetooth: hci4: command 0x0406 tx timeout Bluetooth: hci5: command 0x0406 tx timeout INFO: task kworker/1:2:2865 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:2 D24392 2865 2 0x80000000 Workqueue: events linkwatch_event Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 linkwatch_event+0x9/0x50 net/core/link_watch.c:236 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 INFO: task kworker/0:2:3157 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:2 D26168 3157 2 0x80000000 Workqueue: events_power_efficient reg_check_chans_work Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 reg_check_chans_work+0x73/0xb20 net/wireless/reg.c:2189 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 INFO: task kworker/0:3:3428 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:3 D25464 3428 2 0x80000000 Workqueue: events_power_efficient crda_timeout_work Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 crda_timeout_work+0x9/0x30 net/wireless/reg.c:511 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 INFO: task syz-executor.3:5880 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D23592 5880 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock net/core/rtnetlink.c:77 [inline] rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4800 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x443/0x660 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x667/0xc60 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:661 __sys_sendto+0x1f2/0x2e0 net/socket.c:1897 __do_sys_sendto net/socket.c:1909 [inline] __se_sys_sendto net/socket.c:1905 [inline] __x64_sys_sendto+0xdc/0x1a0 net/socket.c:1905 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x41832c Code: Bad RIP value. RSP: 002b:00007ffd66dc3960 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000001493720 RCX: 000000000041832c RDX: 0000000000000028 RSI: 0000000001493770 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffd66dc39a4 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000003 R15: 0000000001493770 INFO: task syz-executor.0:5883 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D23768 5883 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock net/core/rtnetlink.c:77 [inline] rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4800 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x443/0x660 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x667/0xc60 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:661 __sys_sendto+0x1f2/0x2e0 net/socket.c:1897 __do_sys_sendto net/socket.c:1909 [inline] __se_sys_sendto net/socket.c:1905 [inline] __x64_sys_sendto+0xdc/0x1a0 net/socket.c:1905 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x41832c Code: Bad RIP value. RSP: 002b:00007fff39ab3d30 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000001493720 RCX: 000000000041832c RDX: 0000000000000020 RSI: 0000000001493770 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007fff39ab3d74 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000003 R15: 0000000001493770 INFO: task syz-executor.1:5884 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D23432 5884 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock net/core/rtnetlink.c:77 [inline] rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4800 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x443/0x660 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x667/0xc60 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:661 __sys_sendto+0x1f2/0x2e0 net/socket.c:1897 __do_sys_sendto net/socket.c:1909 [inline] __se_sys_sendto net/socket.c:1905 [inline] __x64_sys_sendto+0xdc/0x1a0 net/socket.c:1905 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x41832c Code: Bad RIP value. RSP: 002b:00007ffd3ecc8660 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000001493720 RCX: 000000000041832c RDX: 0000000000000028 RSI: 0000000001493770 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffd3ecc86a4 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000003 R15: 0000000001493770 INFO: task syz-executor.5:5886 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D23800 5886 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock net/core/rtnetlink.c:77 [inline] rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4800 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x443/0x660 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x667/0xc60 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:661 __sys_sendto+0x1f2/0x2e0 net/socket.c:1897 __do_sys_sendto net/socket.c:1909 [inline] __se_sys_sendto net/socket.c:1905 [inline] __x64_sys_sendto+0xdc/0x1a0 net/socket.c:1905 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x41832c Code: Bad RIP value. RSP: 002b:00007ffef6b70d80 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000001493720 RCX: 000000000041832c RDX: 0000000000000028 RSI: 0000000001493770 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007ffef6b70dc4 R09: 000000000000000c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000003 R15: 0000000001493770 INFO: task kworker/1:3:5916 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:3 D25704 5916 2 0x80000000 Workqueue: ipv6_addrconf addrconf_dad_work Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 addrconf_dad_work+0xa1/0xf70 net/ipv6/addrconf.c:3989 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 INFO: task kworker/0:4:7114 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:4 D25144 7114 2 0x80000000 Workqueue: ipv6_addrconf addrconf_dad_work Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 addrconf_dad_work+0xa1/0xf70 net/ipv6/addrconf.c:3989 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 INFO: task syz-executor.4:7220 blocked for more than 140 seconds. Not tainted 4.19.204-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D25640 7220 5888 0x00000004 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1015 [inline] __mutex_lock+0x4ba/0x1190 kernel/locking/mutex.c:1083 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1098 rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 load_metaops_and_vet net/sched/act_ife.c:281 [inline] populate_metalist net/sched/act_ife.c:456 [inline] tcf_ife_init+0xfb5/0x1590 net/sched/act_ife.c:580 tcf_action_init_1+0x8c6/0xbc0 net/sched/act_api.c:870 tcf_action_init+0x178/0x300 net/sched/act_api.c:936 tcf_action_add+0xf2/0x320 net/sched/act_api.c:1317 tc_ctl_action+0x28d/0x3d0 net/sched/act_api.c:1372 rtnetlink_rcv_msg+0x34f/0x950 net/core/rtnetlink.c:4782 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4800 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x443/0x660 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x667/0xc60 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:661 ___sys_sendmsg+0x647/0x950 net/socket.c:2225 __sys_sendmsg+0xd9/0x180 net/socket.c:2263 __do_sys_sendmsg net/socket.c:2272 [inline] __se_sys_sendmsg net/socket.c:2270 [inline] __x64_sys_sendmsg+0x73/0xb0 net/socket.c:2270 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x465109 Code: Bad RIP value. RSP: 002b:00007f42573fe188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000055cf00 RCX: 0000000000465109 RDX: 0000000000000000 RSI: 0000000020000100 RDI: 0000000000000003 RBP: 00000000004af711 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055cf00 R13: 00007ffdb258fbcf R14: 00007f42573fe300 R15: 0000000000022000 Showing all locks held in the system: 1 lock held by khungtaskd/1095: #0: 000000000697dad3 (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4443 3 locks held by kworker/1:2/2865: #0: 000000009c7d1d9d ((wq_completion)"events"){+.+.}, at: process_one_work+0x6e8/0x15a0 kernel/workqueue.c:2124 #1: 00000000c6bfe5f6 ((linkwatch_work).work){+.+.}, at: process_one_work+0x71b/0x15a0 kernel/workqueue.c:2128 #2: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 3 locks held by kworker/0:2/3157: #0: 000000001e135d2d ((wq_completion)"events_power_efficient"){+.+.}, at: process_one_work+0x6e8/0x15a0 kernel/workqueue.c:2124 #1: 0000000066cfbf39 ((reg_check_chans).work){+.+.}, at: process_one_work+0x71b/0x15a0 kernel/workqueue.c:2128 #2: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 3 locks held by kworker/0:3/3428: #0: 000000001e135d2d ((wq_completion)"events_power_efficient"){+.+.}, at: process_one_work+0x6e8/0x15a0 kernel/workqueue.c:2124 #1: 00000000c4daaf6f ((crda_timeout).work){+.+.}, at: process_one_work+0x71b/0x15a0 kernel/workqueue.c:2128 #2: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 1 lock held by in:imklog/5560: #0: 00000000be77e74b (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:767 1 lock held by syz-executor.3/5880: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 1 lock held by syz-executor.0/5883: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 1 lock held by syz-executor.1/5884: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 1 lock held by syz-executor.5/5886: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 3 locks held by kworker/1:3/5916: #0: 00000000bcf0a729 ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: process_one_work+0x6e8/0x15a0 kernel/workqueue.c:2124 #1: 00000000165308fe ((work_completion)(&(&ifa->dad_work)->work)){+.+.}, at: process_one_work+0x71b/0x15a0 kernel/workqueue.c:2128 #2: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 3 locks held by kworker/0:4/7114: #0: 00000000bcf0a729 ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: process_one_work+0x6e8/0x15a0 kernel/workqueue.c:2124 #1: 00000000eeb508e3 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}, at: process_one_work+0x71b/0x15a0 kernel/workqueue.c:2128 #2: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 1 lock held by syz-executor.4/7220: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 1 lock held by syz-executor.4/7234: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 1 lock held by syz-executor.4/7237: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 1 lock held by syz-executor.2/7229: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock+0x12/0x20 net/core/rtnetlink.c:77 1 lock held by syz-executor.2/7235: 1 lock held by syz-executor.2/7239: #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline] #0: 000000006ce86f05 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x301/0x950 net/core/rtnetlink.c:4779 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1095 Comm: khungtaskd Not tainted 4.19.204-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x17c/0x226 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf5/0x120 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x5c3/0xb40 kernel/hung_task.c:287 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 10 Comm: rcu_preempt Not tainted 4.19.204-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:hlock_class kernel/locking/lockdep.c:145 [inline] RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:2336 [inline] RIP: 0010:validate_chain kernel/locking/lockdep.c:2391 [inline] RIP: 0010:__lock_acquire+0xbe1/0x47c0 kernel/locking/lockdep.c:3416 Code: 91 11 78 05 0f 0b 44 8b 9c 24 98 00 00 00 e9 ed f5 ff ff 48 b8 00 00 00 00 00 fc ff df 48 8b 54 24 70 48 c1 ea 03 0f b6 04 02 <84> c0 74 28 3c 01 7f 24 48 8b 7c 24 70 44 89 5c 24 68 4c 89 94 24 RSP: 0018:ffff8881f56df810 EFLAGS: 00000806 RAX: 0000000000000000 RBX: 00000000bfbebfbc RCX: 1ffff1103ead8d65 RDX: 1ffff1103ead8d65 RSI: ffff8881f56c6b08 RDI: 0000000000000000 RBP: ffff8881f56dfa00 R08: ffff8881f56c6b28 R09: 0000000000000000 R10: ffff8881f56c6b08 R11: 0000000000000001 R12: 00000000bda4bdf1 R13: 00000000bfbe7f3a R14: ffff8881f56c6280 R15: 9810de967d633d2b FS: 0000000000000000(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9469b82000 CR3: 000000000846d006 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x180/0x3a0 kernel/locking/lockdep.c:3908 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152 debug_object_assert_init lib/debugobjects.c:676 [inline] debug_object_assert_init+0xec/0x370 lib/debugobjects.c:665 debug_timer_assert_init kernel/time/timer.c:733 [inline] debug_assert_init kernel/time/timer.c:785 [inline] try_to_del_timer_sync+0x68/0x100 kernel/time/timer.c:1235 del_timer_sync+0x156/0x1e0 kernel/time/timer.c:1305 schedule_timeout+0x3a0/0xd20 kernel/time/timer.c:1819 rcu_gp_kthread+0xd2b/0x23e0 kernel/rcu/tree.c:2202 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 ---------------- Code disassembly (best guess): 0: 91 xchg %eax,%ecx 1: 11 78 05 adc %edi,0x5(%rax) 4: 0f 0b ud2 6: 44 8b 9c 24 98 00 00 mov 0x98(%rsp),%r11d d: 00 e: e9 ed f5 ff ff jmpq 0xfffff600 13: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 1a: fc ff df 1d: 48 8b 54 24 70 mov 0x70(%rsp),%rdx 22: 48 c1 ea 03 shr $0x3,%rdx 26: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax * 2a: 84 c0 test %al,%al <-- trapping instruction 2c: 74 28 je 0x56 2e: 3c 01 cmp $0x1,%al 30: 7f 24 jg 0x56 32: 48 8b 7c 24 70 mov 0x70(%rsp),%rdi 37: 44 89 5c 24 68 mov %r11d,0x68(%rsp) 3c: 4c rex.WR 3d: 89 .byte 0x89 3e: 94 xchg %eax,%esp 3f: 24 .byte 0x24