unregister_netdevice: waiting for syz6 to become free. Usage count = 2 INFO: task syz-executor6:28275 blocked for more than 120 seconds. Not tainted 4.15.0-rc7+ #187 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor6 D25520 28275 4800 0x00000004 Call Trace: context_switch kernel/sched/core.c:2799 [inline] __schedule+0x8eb/0x2060 kernel/sched/core.c:3375 schedule+0xf5/0x430 kernel/sched/core.c:3434 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3492 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 sock_ioctl+0x367/0x440 net/socket.c:1020 vfs_ioctl fs/ioctl.c:46 [inline] do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 entry_SYSCALL_64_fastpath+0x23/0x9a RIP: 0033:0x452cf9 RSP: 002b:00007fb4d3344c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fb4d3345700 RCX: 0000000000452cf9 RDX: 0000000020ec4ff0 RSI: 00000000000089a1 RDI: 0000000000000016 RBP: 0000000000a2f870 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000 R13: 0000000000a2f7ef R14: 00007fb4d33459c0 R15: 0000000000000001 Showing all locks held in the system: 2 locks held by khungtaskd/748: #0: (rcu_read_lock){....}, at: [<00000000ca775926>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] #0: (rcu_read_lock){....}, at: [<00000000ca775926>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249 #1: (tasklist_lock){.+.+}, at: [<000000006530619b>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4464 4 locks held by rs:main Q:Reg/3503: #0: (&f->f_pos_lock){+.+.}, at: [<0000000059a6cc94>] __fdget_pos+0x12b/0x190 fs/file.c:770 #1: (sb_writers#4){.+.+}, at: [<000000004594f7a6>] file_start_write include/linux/fs.h:2715 [inline] #1: (sb_writers#4){.+.+}, at: [<000000004594f7a6>] vfs_write+0x407/0x510 fs/read_write.c:543 #2: (&sb->s_type->i_mutex_key#10){+.+.}, at: [<000000000c5b5f34>] inode_trylock include/linux/fs.h:733 [inline] #2: (&sb->s_type->i_mutex_key#10){+.+.}, at: [<000000000c5b5f34>] ext4_file_write_iter+0x21f/0x10c0 fs/ext4/file.c:232 #3: (jbd2_handle){.+.+}, at: [<00000000da16a009>] start_this_handle+0x488/0x1080 fs/jbd2/transaction.c:388 2 locks held by getty/3627: #0: (&tty->ldisc_sem){++++}, at: [<00000000ebf5c401>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000011251e95>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3628: #0: (&tty->ldisc_sem){++++}, at: [<00000000ebf5c401>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000011251e95>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3629: #0: (&tty->ldisc_sem){++++}, at: [<00000000ebf5c401>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000011251e95>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3630: #0: (&tty->ldisc_sem){++++}, at: [<00000000ebf5c401>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000011251e95>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3631: #0: (&tty->ldisc_sem){++++}, at: [<00000000ebf5c401>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000011251e95>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3632: #0: (&tty->ldisc_sem){++++}, at: [<00000000ebf5c401>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000011251e95>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 2 locks held by getty/3633: #0: (&tty->ldisc_sem){++++}, at: [<00000000ebf5c401>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (&ldata->atomic_read_lock){+.+.}, at: [<0000000011251e95>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 1 lock held by syz-executor6/28250: #0: (br_ioctl_mutex){+.+.}, at: [<00000000432d75d9>] sock_ioctl+0x367/0x440 net/socket.c:1020 1 lock held by syz-executor6/28275: #0: (br_ioctl_mutex){+.+.}, at: [<00000000432d75d9>] sock_ioctl+0x367/0x440 net/socket.c:1020 1 lock held by syz-executor6/28276: #0: (br_ioctl_mutex){+.+.}, at: [<00000000432d75d9>] sock_ioctl+0x367/0x440 net/socket.c:1020 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 748 Comm: khungtaskd Not tainted 4.15.0-rc7+ #187 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x257 lib/dump_stack.c:53 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x122/0x180 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:138 [inline] check_hung_task kernel/hung_task.c:132 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] watchdog+0x90c/0xd60 kernel/hung_task.c:249 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc7+ #187 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:llist_del_all include/linux/llist.h:234 [inline] RIP: 0010:sched_ttwu_pending+0x73/0x270 kernel/sched/core.c:1752 RSP: 0018:ffff8801db307cc0 EFLAGS: 00000046 RAX: ffffed003b660f9b RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8801d9f66b44 RBP: ffff8801db307d60 R08: 0000000000000001 R09: ffff88021fff8048 R10: ffff88021fff8050 R11: ffff88021fff805d R12: ffff8801db32c240 R13: 1ffff1003b660f9b R14: dffffc0000000000 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000da0cd8 CR3: 0000000006822003 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: scheduler_ipi+0x242/0x820 kernel/sched/core.c:1794 smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277 reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:944 RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 RSP: 0018:ffff8801d9f77cb0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: 1ffff1003b3eef99 RCX: 0000000000000000 RDX: 1ffffffff0d19078 RSI: 0000000000000001 RDI: ffffffff868c83c0 RBP: ffff8801d9f77cb0 R08: ffffffff86677ae8 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 R13: ffff8801d9f77d68 R14: ffffffff8703d260 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] default_idle+0xbf/0x460 arch/x86/kernel/process.c:355 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:346 default_idle_call+0x36/0x90 kernel/sched/idle.c:98 cpuidle_idle_call kernel/sched/idle.c:156 [inline] do_idle+0x24a/0x3b0 kernel/sched/idle.c:246 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:351 start_secondary+0x40a/0x590 arch/x86/kernel/smpboot.c:268 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 Code: 88 50 eb 4c 81 c7 00 f1 f1 f1 f1 c7 40 04 00 00 f2 f2 c7 40 08 f3 f3 f3 f3 65 4c 03 25 7f 95 b4 7e 31 db 49 87 9c 24 a0 0b 00 00 <48> 85 db 0f 84 60 01 00 00 48 8d 45 d8 4c 89 e7 48 89 85 70 ff