INFO: task syz-executor.2:16847 blocked for more than 140 seconds. Not tainted 4.19.127-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27704 16847 6611 0x00000006 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x8a2/0x1fc0 kernel/sched/core.c:3515 schedule+0x8d/0x1b0 kernel/sched/core.c:3559 schedule_timeout+0x8f3/0xed0 kernel/time/timer.c:1782 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common+0x29c/0x470 kernel/sched/completion.c:115 __flush_work+0x48b/0x870 kernel/workqueue.c:2928 flush_all_backlogs net/core/dev.c:5289 [inline] rollback_registered_many+0x493/0xc40 net/core/dev.c:8178 rollback_registered+0xf2/0x1c0 net/core/dev.c:8235 unregister_netdevice_queue+0x1d7/0x2b0 net/core/dev.c:9290 unregister_netdevice include/linux/netdevice.h:2614 [inline] unregister_netdev+0x18/0x20 net/core/dev.c:9331 mkiss_close+0x17d/0x1f0 drivers/net/hamradio/mkiss.c:812 tty_ldisc_close.isra.0+0xa2/0xd0 drivers/tty/tty_ldisc.c:493 tty_ldisc_kill+0x46/0xc0 drivers/tty/tty_ldisc.c:639 tty_ldisc_release+0xbe/0x270 drivers/tty/tty_ldisc.c:806 tty_release_struct+0x16/0x50 drivers/tty/tty_io.c:1611 tty_release+0xbc9/0xe90 drivers/tty/tty_io.c:1784 __fput+0x2cd/0x890 fs/file_table.c:278 task_work_run+0x13f/0x1b0 kernel/task_work.c:113 get_signal+0x1b2e/0x1f30 kernel/signal.c:2399 do_signal+0x8f/0x1620 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x204/0x2a0 arch/x86/entry/common.c:163 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45ca69 Code: Bad RIP value. RSP: 002b:00007fa08bc60c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: 0000000000000000 RBX: 00000000004ef500 RCX: 000000000045ca69 RDX: 0000000020000000 RSI: 0000000000005423 RDI: 0000000000000004 RBP: 000000000078c040 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000591 R14: 00000000004c84da R15: 00007fa08bc616d4 Showing all locks held in the system: 1 lock held by khungtaskd/1077: #0: 00000000e05e7060 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440 1 lock held by systemd-journal/3684: 1 lock held by in:imklog/6196: 1 lock held by syz-executor.3/15008: 4 locks held by syz-executor.2/16847: #0: 00000000829803a9 (&tty->ldisc_sem){++++}, at: __tty_ldisc_lock drivers/tty/tty_ldisc.c:320 [inline] #0: 00000000829803a9 (&tty->ldisc_sem){++++}, at: tty_ldisc_lock_pair_timeout drivers/tty/tty_ldisc.c:376 [inline] #0: 00000000829803a9 (&tty->ldisc_sem){++++}, at: tty_ldisc_lock_pair drivers/tty/tty_ldisc.c:397 [inline] #0: 00000000829803a9 (&tty->ldisc_sem){++++}, at: tty_ldisc_release+0x104/0x270 drivers/tty/tty_ldisc.c:805 #1: 000000002fa7584f (&tty->ldisc_sem/1){+.+.}, at: __tty_ldisc_lock_nested drivers/tty/tty_ldisc.c:326 [inline] #1: 000000002fa7584f (&tty->ldisc_sem/1){+.+.}, at: tty_ldisc_lock_pair_timeout drivers/tty/tty_ldisc.c:378 [inline] #1: 000000002fa7584f (&tty->ldisc_sem/1){+.+.}, at: tty_ldisc_lock_pair drivers/tty/tty_ldisc.c:397 [inline] #1: 000000002fa7584f (&tty->ldisc_sem/1){+.+.}, at: tty_ldisc_release+0x19a/0x270 drivers/tty/tty_ldisc.c:805 #2: 000000007d33f6cc (rtnl_mutex){+.+.}, at: unregister_netdev+0xe/0x20 net/core/dev.c:9330 #3: 000000006ee47484 (cpu_hotplug_lock.rw_sem){++++}, at: get_online_cpus include/linux/cpu.h:137 [inline] #3: 000000006ee47484 (cpu_hotplug_lock.rw_sem){++++}, at: flush_all_backlogs net/core/dev.c:5282 [inline] #3: 000000006ee47484 (cpu_hotplug_lock.rw_sem){++++}, at: rollback_registered_many+0x387/0xc40 net/core/dev.c:8178 1 lock held by systemd-udevd/16903: #0: 000000007d33f6cc (rtnl_mutex){+.+.}, at: dev_ioctl+0x4b8/0xc58 net/core/dev_ioctl.c:422 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1077 Comm: khungtaskd Not tainted 4.19.127-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+0x1fc/0x2fe lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x962/0xe40 kernel/hung_task.c:287 kthread+0x30b/0x410 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 15008 Comm: syz-executor.3 Not tainted 4.19.127-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:unwind_next_frame+0xecf/0x1b10 arch/x86/kernel/unwind_orc.c:513 Code: 48 8b 4c 24 20 80 3c 02 00 4c 8b 44 24 28 0f 85 80 08 00 00 48 8b 14 24 4d 89 67 38 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 3e 08 00 00 49 8d 7f 58 49 c7 47 50 00 00 00 00 RSP: 0000:ffff888054537888 EFLAGS: 00000806 RAX: dffffc0000000000 RBX: 1ffff1100a8a6f19 RCX: ffffffff89eb5748 RDX: 1ffff1100a8a6f36 RSI: ffff888054537820 RDI: ffff888054537ef0 RBP: 0000000000000001 R08: ffffffff89eb574c R09: 0000000000000001 R10: 000000000000815f R11: 0000000000064061 R12: ffff888054537ef8 R13: ffff888054537995 R14: ffff888054537998 R15: ffff888054537960 FS: 00007f0bbdb9f700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000488a8ef8 CR3: 00000000a065c000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __save_stack_trace+0x83/0x100 arch/x86/kernel/stacktrace.c:44 save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x128/0x1f0 mm/kasan/kasan.c:521 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x7f/0x260 mm/slab.c:3765 __sigqueue_free kernel/signal.c:447 [inline] dequeue_synchronous_signal kernel/signal.c:736 [inline] get_signal+0xd7c/0x1f30 kernel/signal.c:2478 do_signal+0x8f/0x1620 arch/x86/kernel/signal.c:821 exit_to_usermode_loop+0x204/0x2a0 arch/x86/entry/common.c:163 prepare_exit_to_usermode+0x27b/0x2e0 arch/x86/entry/common.c:198 retint_user+0x8/0x18 RIP: 0033:0x405dd9 Code: d0 ff ff ff 01 48 8b 7c 24 28 c7 44 24 34 00 00 00 00 e8 0a ef 01 00 85 c0 75 23 48 6b 44 24 20 18 8b 7c 24 1c 48 03 44 24 38 <48> 8b 48 10 48 8b 50 08 48 8b 30 e8 a7 0a 01 00 89 44 24 34 64 f0 RSP: 002b:00007f0bbdb9ea70 EFLAGS: 00010206 RAX: 00000000488a8ee8 RBX: 0000000000509440 RCX: 00000000004168c7 RDX: 2a670cae5c3e4a1d RSI: 0000000000000000 RDI: 0000000000000007 RBP: 000000000078c0e0 R08: 00007f0bbdb9ea70 R09: 000000000078c0e0 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff R13: 0000000000000c0e R14: 00000000004ce5f6 R15: 00007f0bbdb9f6d4