INFO: task udevd:25783 bl INFO: task udevd:25783 blocked in I/O wait for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:udevd state:D stack:26336 pid:25783 tgid:25783 ppid:4999 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5583 [inline] __schedule+0x17dd/0x5830 kernel/sched/core.c:7382 __schedule_loop kernel/sched/core.c:7459 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7474 io_schedule+0x7f/0xd0 kernel/sched/core.c:8146 folio_wait_bit_common+0x6d0/0xcf0 mm/filemap.c:1327 folio_put_wait_locked mm/filemap.c:1508 [inline] do_read_cache_folio+0x1ac/0x590 mm/filemap.c:4156 read_mapping_folio include/linux/pagemap.h:1012 [inline] read_part_sector+0xb6/0x2b0 block/partitions/core.c:724 adfspart_check_POWERTEC+0x9a/0x7a0 block/partitions/acorn.c:451 check_partition block/partitions/core.c:143 [inline] blk_add_partitions block/partitions/core.c:591 [inline] bdev_disk_changed+0x851/0x1680 block/partitions/core.c:695 blkdev_get_whole+0x372/0x510 block/bdev.c:793 bdev_open+0x324/0xd70 block/bdev.c:1002 blkdev_open+0x461/0x600 block/fops.c:686 do_dentry_open+0x80e/0x1360 fs/open.c:1000 vfs_open_consume+0x4a/0x350 fs/open.c:1131 do_open fs/namei.c:4851 [inline] path_openat+0x16fc/0x20f0 fs/namei.c:5016 do_file_open+0x23e/0x4a0 fs/namei.c:5045 do_sys_openat2+0x115/0x200 fs/open.c:1442 do_sys_open fs/open.c:1448 [inline] __do_sys_openat fs/open.c:1464 [inline] __se_sys_openat fs/open.c:1459 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1459 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fde13aa7407 RSP: 002b:00007ffd8ab7c7f0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fde1417a880 RCX: 00007fde13aa7407 RDX: 00000000000a0800 RSI: 0000564b52343010 RDI: ffffffffffffff9c RBP: 0000564b52335910 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000564b52373c00 R13: 0000564b52343190 R14: 0000000000000000 R15: 0000564b52373c00 Showing all locks held in the system: locks held by khungtaskd/32: 1, last CPU#0: #0: ffffffff9015a2a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff9015a2a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff9015a2a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871 locks held by getty/5386: 2, on CPU#1: #0: ffff8880367ea0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000322e2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211 locks held by kworker/u8:9/11986: 3, on CPU#0: #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88813fe4c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc9001b04fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc9001b04fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc9001b04fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc9001b04fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313 locks held by udevd/25783: 1, on CPU#0: #0: ffff888027428350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70 block/bdev.c:990 locks held by kworker/u8:5/30917: 3, on CPU#0: #0: ffff88801ebeb148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801ebeb148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801ebeb148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #0: ffff88801ebeb148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #1: ffffc9000d9d7c40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc9000d9d7c40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc9000d9d7c40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline] #1: ffffc9000d9d7c40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578 #2: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline] #2: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x19/0x30 net/ipv6/addrconf.c:4796 locks held by syz.3.13259/3178: 1, last CPU#0: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:654 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3608 locks held by syz.1.13265/3207: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3da/0x1e70 drivers/net/tun.c:3250 locks held by syz.1.13265/3220: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:366 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xc1d/0x1c30 net/core/rtnetlink.c:4251 locks held by syz.1.13265/3225: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7175 locks held by syz.1.13265/3231: 1, on CPU#0: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7175 locks held by syz.0.13266/3211: 1, on CPU#0: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3da/0x1e70 drivers/net/tun.c:3250 locks held by syz.0.13266/3224: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7175 locks held by syz.0.13266/3230: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: dev_ioctl+0x7a4/0x1150 net/core/dev_ioctl.c:809 locks held by syz.2.13267/3223: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3da/0x1e70 drivers/net/tun.c:3250 locks held by syz.2.13267/3229: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:654 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3608 locks held by syz.2.13267/3232: 3, on CPU#0: #0: ffffffff916f7ba8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff916f79e0 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline] #1: ffffffff916f79e0 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline] #1: ffffffff916f79e0 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1208 #2: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: __tipc_nl_compat_doit net/tipc/netlink_compat.c:359 [inline] #2: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: tipc_nl_compat_doit+0x22a/0x650 net/tipc/netlink_compat.c:394 locks held by syz.2.13267/3239: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: dev_ioctl+0x7a4/0x1150 net/core/dev_ioctl.c:809 locks held by syz.2.13267/3246: 1, on CPU#0: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7175 locks held by syz.2.13267/3252: 1, on CPU#0: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7175 locks held by syz.4.13268/3256: 1, on CPU#0: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3da/0x1e70 drivers/net/tun.c:3250 locks held by syz.4.13268/3257: 1, on CPU#0: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:654 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3608 locks held by syz.4.13268/3259: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7175 locks held by syz.4.13268/3261: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7175 locks held by syz.4.13268/3262: 1, on CPU#1: #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline] #0: ffffffff916937a0 (rtnl_mutex){+.+.}-{4:4}, at: dev_ioctl+0x7a4/0x1150 net/core/dev_ioctl.c:809 ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123 nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66 trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x135/0x170 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:377 [inline] watchdog+0x1073/0x10f0 kernel/hung_task.c:598 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026 RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:425 Code: e8 9e 97 43 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 9f 20 bb fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 5a 2f 83 06 cc 44 89 f9 80 e1 07 RSP: 0018:ffffc90000a778b8 EFLAGS: 00000002 RAX: 1ffffffff3840b00 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020 RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: ffffffff85857980 R12: dffffc0000000000 R13: 0000000000000000 R14: ffffffff9c205ec0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888123509000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055555963d4e8 CR3: 000000006484e000 CR4: 00000000003526f0 Call Trace: serial_in drivers/tty/serial/8250/8250.h:134 [inline] serial_lsr_in drivers/tty/serial/8250/8250.h:156 [inline] wait_for_lsr+0x184/0x2f0 drivers/tty/serial/8250/8250_port.c:2036 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3294 [inline] __serial8250_console_fifo_write+0xcd/0x3e0 drivers/tty/serial/8250/8250_port.c:3369 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3402 [inline] __serial8250_console_write drivers/tty/serial/8250/8250_port.c:3456 [inline] serial8250_console_write+0xa7e/0x1200 drivers/tty/serial/8250/8250_port.c:3520 nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1 nbcon_emit_one kernel/printk/nbcon.c:1157 [inline] nbcon_kthread_func+0x6d9/0x8d0 kernel/printk/nbcon.c:1271 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245