Hello, syzbot found the following issue on: HEAD commit: b36c9697 Add linux-next specific files for 20200828 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=16660271900000 kernel config: https://syzkaller.appspot.com/x/.config?x=5e3cf99580b5542c dashboard link: https://syzkaller.appspot.com/bug?extid=df649192fec7dd1beaa7 compiler: gcc (GCC) 10.1.0-syz 20200507 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+df649192fec7dd1beaa7@xxxxxxxxxxxxxxxxxxxxxxxxx INFO: task syz-executor.4:10877 can't die for more than 143 seconds. task:syz-executor.4 state:D stack:29424 pid:10877 ppid: 6874 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:3778 [inline] __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527 schedule+0xd0/0x2a0 kernel/sched/core.c:4602 rwsem_down_write_slowpath+0x603/0xc60 kernel/locking/rwsem.c:1235 __down_write kernel/locking/rwsem.c:1389 [inline] down_write+0x137/0x150 kernel/locking/rwsem.c:1532 register_netdevice_notifier+0x1e/0x260 net/core/dev.c:1814 bcm_init+0x1a3/0x210 net/can/bcm.c:1451 can_create+0x27c/0x4d0 net/can/af_can.c:168 __sock_create+0x3ca/0x740 net/socket.c:1427 sock_create net/socket.c:1478 [inline] __sys_socket+0xef/0x200 net/socket.c:1520 __do_sys_socket net/socket.c:1529 [inline] __se_sys_socket net/socket.c:1527 [inline] __x64_sys_socket+0x6f/0xb0 net/socket.c:1527 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: Bad RIP value. RSP: 002b:00007f336efccc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000029 RAX: ffffffffffffffda RBX: 0000000000032b40 RCX: 000000000045d5b9 RDX: 0000000000000002 RSI: 0000000000000002 RDI: 000000000000001d RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffed071b14f R14: 00007f336efcd9c0 R15: 000000000118cf4c INFO: task syz-executor.4:10877 blocked for more than 143 seconds. Not tainted 5.9.0-rc2-next-20200828-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.4 state:D stack:29424 pid:10877 ppid: 6874 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:3778 [inline] __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527 schedule+0xd0/0x2a0 kernel/sched/core.c:4602 rwsem_down_write_slowpath+0x603/0xc60 kernel/locking/rwsem.c:1235 __down_write kernel/locking/rwsem.c:1389 [inline] down_write+0x137/0x150 kernel/locking/rwsem.c:1532 register_netdevice_notifier+0x1e/0x260 net/core/dev.c:1814 bcm_init+0x1a3/0x210 net/can/bcm.c:1451 can_create+0x27c/0x4d0 net/can/af_can.c:168 __sock_create+0x3ca/0x740 net/socket.c:1427 sock_create net/socket.c:1478 [inline] __sys_socket+0xef/0x200 net/socket.c:1520 __do_sys_socket net/socket.c:1529 [inline] __se_sys_socket net/socket.c:1527 [inline] __x64_sys_socket+0x6f/0xb0 net/socket.c:1527 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: Bad RIP value. RSP: 002b:00007f336efccc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000029 RAX: ffffffffffffffda RBX: 0000000000032b40 RCX: 000000000045d5b9 RDX: 0000000000000002 RSI: 0000000000000002 RDI: 000000000000001d RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffed071b14f R14: 00007f336efcd9c0 R15: 000000000118cf4c INFO: task syz-executor.4:10881 can't die for more than 144 seconds. task:syz-executor.4 state:D stack:29792 pid:10881 ppid: 6874 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:3778 [inline] __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527 schedule+0xd0/0x2a0 kernel/sched/core.c:4602 rwsem_down_write_slowpath+0x603/0xc60 kernel/locking/rwsem.c:1235 __down_write kernel/locking/rwsem.c:1389 [inline] down_write+0x137/0x150 kernel/locking/rwsem.c:1532 register_netdevice_notifier+0x1e/0x260 net/core/dev.c:1814 bcm_init+0x1a3/0x210 net/can/bcm.c:1451 can_create+0x27c/0x4d0 net/can/af_can.c:168 __sock_create+0x3ca/0x740 net/socket.c:1427 sock_create net/socket.c:1478 [inline] __sys_socket+0xef/0x200 net/socket.c:1520 __do_sys_socket net/socket.c:1529 [inline] __se_sys_socket net/socket.c:1527 [inline] __x64_sys_socket+0x6f/0xb0 net/socket.c:1527 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: Bad RIP value. RSP: 002b:00007f336edccc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000029 RAX: ffffffffffffffda RBX: 0000000000032b40 RCX: 000000000045d5b9 RDX: 0000000000000002 RSI: 0000000000000002 RDI: 000000000000001d RBP: 000000000118d0c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118d08c R13: 00007ffed071b14f R14: 00007f336edcd9c0 R15: 000000000118d08c INFO: task syz-executor.4:10881 blocked for more than 144 seconds. Not tainted 5.9.0-rc2-next-20200828-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.4 state:D stack:29792 pid:10881 ppid: 6874 flags:0x00000004 Call Trace: context_switch kernel/sched/core.c:3778 [inline] __schedule+0x8e5/0x21e0 kernel/sched/core.c:4527 schedule+0xd0/0x2a0 kernel/sched/core.c:4602 rwsem_down_write_slowpath+0x603/0xc60 kernel/locking/rwsem.c:1235 __down_write kernel/locking/rwsem.c:1389 [inline] down_write+0x137/0x150 kernel/locking/rwsem.c:1532 register_netdevice_notifier+0x1e/0x260 net/core/dev.c:1814 bcm_init+0x1a3/0x210 net/can/bcm.c:1451 can_create+0x27c/0x4d0 net/can/af_can.c:168 __sock_create+0x3ca/0x740 net/socket.c:1427 sock_create net/socket.c:1478 [inline] __sys_socket+0xef/0x200 net/socket.c:1520 __do_sys_socket net/socket.c:1529 [inline] __se_sys_socket net/socket.c:1527 [inline] __x64_sys_socket+0x6f/0xb0 net/socket.c:1527 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: Bad RIP value. RSP: 002b:00007f336edccc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000029 RAX: ffffffffffffffda RBX: 0000000000032b40 RCX: 000000000045d5b9 RDX: 0000000000000002 RSI: 0000000000000002 RDI: 000000000000001d RBP: 000000000118d0c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118d08c R13: 00007ffed071b14f R14: 00007f336edcd9c0 R15: 000000000118d08c Showing all locks held in the system: 2 locks held by kworker/u4:2/80: #0: ffff8880ae635f98 (&rq->lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1292 [inline] #0: ffff8880ae635f98 (&rq->lock){-.-.}-{2:2}, at: __schedule+0x232/0x21e0 kernel/sched/core.c:4445 #1: ffff8880ae620ec8 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x2fb/0x400 kernel/sched/psi.c:833 1 lock held by khungtaskd/1169: #0: ffffffff89c67640 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5825 1 lock held by in:imklog/6548: #0: ffff888093dd26b0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930 2 locks held by rs:main Q:Reg/6549: #0: ffff88809deee130 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:930 #1: ffff888098aea460 (sb_writers#4){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2790 [inline] #1: ffff888098aea460 (sb_writers#4){.+.+}-{0:0}, at: vfs_write+0x54f/0x730 fs/read_write.c:574 3 locks held by kworker/u4:8/8625: 1 lock held by syz-executor.4/10877: #0: ffffffff8a879430 (pernet_ops_rwsem){++++}-{3:3}, at: register_netdevice_notifier+0x1e/0x260 net/core/dev.c:1814 1 lock held by syz-executor.4/10881: #0: ffffffff8a879430 (pernet_ops_rwsem){++++}-{3:3}, at: register_netdevice_notifier+0x1e/0x260 net/core/dev.c:1814 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1169 Comm: khungtaskd Not tainted 5.9.0-rc2-next-20200828-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+0x18f/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x223 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline] watchdog+0xd89/0xf30 kernel/hung_task.c:339 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 8625 Comm: kworker/u4:8 Not tainted 5.9.0-rc2-next-20200828-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net RIP: 0010:lock_acquire+0x1e/0xad0 kernel/locking/lockdep.c:4977 Code: 66 90 66 2e 0f 1f 84 00 00 00 00 00 41 57 41 56 41 89 d6 41 55 49 89 fd 41 54 41 89 cc 48 b9 00 00 00 00 00 fc ff df 55 89 f5 <53> 44 89 c3 48 81 ec c0 00 00 00 48 8d 44 24 20 4c 89 0c 24 48 c7 RSP: 0018:ffffc900065ffb40 EFLAGS: 00000246 RAX: 0000000000000201 RBX: 0000000000010000 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff89a6be98 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: 000000000000160f R11: 0000000000000001 R12: 0000000000000000 R13: ffffffff89a6be98 R14: 0000000000000000 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8fc077f000 CR3: 000000009f467000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:354 [inline] nf_conntrack_lock net/netfilter/nf_conntrack_core.c:91 [inline] get_next_corpse net/netfilter/nf_conntrack_core.c:2204 [inline] nf_ct_iterate_cleanup+0x102/0x330 net/netfilter/nf_conntrack_core.c:2249 nf_conntrack_cleanup_net_list+0x81/0x250 net/netfilter/nf_conntrack_core.c:2436 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:189 cleanup_net+0x4ea/0xb10 net/core/net_namespace.c:603 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 --- This report is generated by a bot. 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