INFO: task syz.3.937:9807 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disabl "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.3.937 state:D stack:27584 pid:9807 tgid:9789 ppid:5638 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7284 __schedule_loop kernel/sched/core.c:7361 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7376 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7433 __mutex_lock_common kernel/locking/mutex.c:726 [inline] __mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821 nfsd_nl_version_set_doit+0xcd/0x7a0 fs/nfsd/nfsctl.c:1844 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800 __sock_sendmsg net/socket.c:818 [inline] sock_write_iter+0x2de/0x3e0 net/socket.c:1269 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x612/0xba0 fs/read_write.c:687 ksys_write+0x150/0x270 fs/read_write.c:739 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: 0033:0x7f3e0bf9e159 RSP: 002b:00007f3e0cd81028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f3e0c226090 RCX: 00007f3e0bf9e159 RDX: 000000000000002c RSI: 0000200000000000 RDI: 0000000000000003 RBP: 00007f3e0c03506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3e0c226128 R14: 00007f3e0c226090 R15: 00007ffc5b12dd58 Showing all locks held in the system: locks held by kworker/0:0/9: 3, on CPU#0: #0: ffff88801b06b140 ((wq_completion)events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801b06b140 ((wq_completion)events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801b06b140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff88801b06b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc900000e7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc900000e7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc900000e7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc900000e7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #2: ffff8880296ca250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1fd/0x3b0 drivers/net/netdevsim/fib.c:1490 locks held by pr/ttyS0/16: 2, last CPU#0: #0: ffffffff8ec36538 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline] #0: ffffffff8ec36538 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline] #0: ffffffff8ec36538 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291 #1: ffffffff9ad2d2d8 (&port_lock_key){-.-.}-{3:3}, at: __uart_port_lock_irqsave include/linux/serial_core.h:613 [inline] #1: ffffffff9ad2d2d8 (&port_lock_key){-.-.}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0 drivers/tty/serial/8250/8250_core.c:413 locks held by khungtaskd/31: 1, last CPU#1: #0: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871 locks held by getty/5372: 2, on CPU#0: #0: ffff8880288b40a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211 locks held by kworker/0:8/5751: 2, on CPU#0: #0: ffff88801b06b140 ((wq_completion)events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801b06b140 ((wq_completion)events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801b06b140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff88801b06b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc90004c5fc40 (free_ipc_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc90004c5fc40 (free_ipc_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc90004c5fc40 (free_ipc_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc90004c5fc40 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 locks held by syz.4.932/9762: 2, on CPU#1: #0: ffffffff902b8e28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8f09f900 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x53d/0x1ab0 fs/nfsd/nfsctl.c:2057 locks held by syz.3.937/9807: 2, on CPU#0: #0: ffffffff902b8e28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8f09f900 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xcd/0x7a0 fs/nfsd/nfsctl.c:1844 locks held by syz.6.1509/12010: 2, on CPU#1: #0: ffffffff902b8e28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8f09f900 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_unlock_filesystem_doit+0x2af/0x410 fs/nfsd/nfsctl.c:2677 locks held by syz.5.1629/12512: 2, on CPU#0: #0: ffffffff902b8e28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8f09f900 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x53d/0x1ab0 fs/nfsd/nfsctl.c:2057 locks held by syz-executor/12666: 4, last CPU#1: #0: ffffffff8ee36730 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1542 [inline] #0: ffffffff8ee36730 (dup_mmap_sem){++++}-{0:0}, at: copy_mm+0x10f/0x480 kernel/fork.c:1595 #1: ffff888031ea29f8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline] #1: ffff888031ea29f8 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x195/0x1dc0 mm/mmap.c:1716 #2: ffff88803565a9f8 (&mm->mmap_lock/1){+.+.}-{4:4}, at: mmap_write_lock_nested include/linux/mmap_lock.h:552 [inline] #2: ffff88803565a9f8 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x221/0x1dc0 mm/mmap.c:1723 #3: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #3: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #3: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240 mm/pgtable-generic.c:290 locks held by syz.1.1937/13844: 2, on CPU#0: #0: ffffffff902b8e28 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8f09f900 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_svc_export_set_reqs_doit+0x132/0x1480 fs/nfsd/export.c:1057 locks held by kworker/u8:34/14407: 3, on CPU#0: #0: ffff88801c2d6140 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801c2d6140 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801c2d6140 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff88801c2d6140 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc900039cfc40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc900039cfc40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc900039cfc40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc900039cfc40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #2: ffffffff90246148 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810 net/core/net_namespace.c:677 locks held by kworker/u8:39/14413: 2, on CPU#0: #0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 #1: ffffc9000394fc40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffc9000394fc40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffc9000394fc40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline] #1: ffffc9000394fc40 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479 locks held by syz.2.2441/15860: 2, last CPU#1: #0: ffff888072d803b8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline] #0: ffff888072d803b8 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x1a4/0x9f0 mm/mmap.c:1299 #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240 mm/pgtable-generic.c:290 locks held by syz.0.2449/15888: 1, last CPU#1: #0: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock_dont_migrate include/linux/rcupdate.h:991 [inline] #0: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: bpf_test_timer_enter+0xf9/0x260 net/bpf/test_run.c:39 locks held by syz.0.2449/15892: 2, on CPU#0: #0: ffff888033c578e0 (&nft_net->commit_mutex){+.+.}-{4:4}, at: nf_tables_valid_genid+0x3e/0x100 net/netfilter/nf_tables_api.c:11540 #1: ffffffff8ed62ce8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline] #1: ffffffff8ed62ce8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770 kernel/rcu/tree_exp.h:966 locks held by syz.9.2450/15887: 2, on CPU#0: #0: ffff888076529f00 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline] #0: ffff888076529f00 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: __sock_release+0x7a/0x1f0 net/socket.c:734 #1: ffffffff8ed62ce8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline] #1: ffffffff8ed62ce8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770 kernel/rcu/tree_exp.h:966 locks held by syz.8.2456/15917: 4, last CPU#1: #0: ffff88803612f588 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500 mm/mmap_lock.c:310 #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: do_fault_around mm/memory.c:5957 [inline] #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: do_read_fault mm/memory.c:5991 [inline] #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: do_fault mm/memory.c:6134 [inline] #1: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: do_pte_missing+0x140c/0x34b0 mm/memory.c:4700 #2: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #2: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #2: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: filemap_map_pages+0x1d1/0x2170 mm/filemap.c:3921 #3: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #3: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #3: ffffffff8ed5c920 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240 mm/pgtable-generic.c:290 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 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:353 [inline] watchdog+0xfd7/0x1030 kernel/hung_task.c:561 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 16 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409 Code: e8 be 9a 54 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 ff 9e c4 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07 RSP: 0018:ffffc900001578b8 EFLAGS: 00000002 RAX: 1ffffffff35a5a00 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020 RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: ffffffff857340f0 R12: dffffc0000000000 R13: 0000000000000000 R14: ffffffff9ad2d300 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888124cde000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f464df37000 CR3: 000000003729e000 CR4: 00000000003526f0 Call Trace: serial_in drivers/tty/serial/8250/8250.h:128 [inline] serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline] wait_for_lsr+0x184/0x2f0 drivers/tty/serial/8250/8250_port.c:2013 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3270 [inline] __serial8250_console_fifo_write+0xcd/0x3e0 drivers/tty/serial/8250/8250_port.c:3345 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3378 [inline] __serial8250_console_write drivers/tty/serial/8250/8250_port.c:3429 [inline] serial8250_console_write+0xaa1/0x1200 drivers/tty/serial/8250/8250_port.c:3493 nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1 nbcon_emit_one kernel/printk/nbcon.c:1157 [inline] nbcon_kthread_func+0x679/0x880 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