INFO: task udevd:19130 blocked 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:23400 pid:19130 tgid:19130 ppid:5192   task_flags:0x400140 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x17b4/0x5680 kernel/sched/core.c:7183
 __schedule_loop kernel/sched/core.c:7262 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7277
 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
 wait_for_reconnect drivers/block/nbd.c:1107 [inline]
 nbd_handle_cmd drivers/block/nbd.c:1149 [inline]
 nbd_queue_rq+0x857/0x1100 drivers/block/nbd.c:1207
 blk_mq_dispatch_rq_list+0xa70/0x1910 block/blk-mq.c:2148
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
 __blk_mq_sched_dispatch_requests+0xdcc/0x1600 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
 blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386
 blk_mq_dispatch_list+0xd16/0xe10 include/linux/spinlock.h:-1
 blk_mq_flush_plug_list+0x48d/0x570 block/blk-mq.c:2997
 __blk_flush_plug+0x3ed/0x4d0 block/blk-core.c:1230
 blk_finish_plug block/blk-core.c:1257 [inline]
 __submit_bio+0x28d/0x580 block/blk-core.c:649
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x2f4/0xa40 block/blk-core.c:753
 submit_bh fs/buffer.c:2735 [inline]
 block_read_full_folio+0x7b7/0x830 fs/buffer.c:2351
 filemap_read_folio+0x137/0x3b0 mm/filemap.c:2501
 do_read_cache_folio+0x358/0x590 mm/filemap.c:4106
 read_mapping_folio include/linux/pagemap.h:1017 [inline]
 read_part_sector+0xb6/0x2b0 block/partitions/core.c:724
 adfspart_check_ICS+0xb1/0x960 block/partitions/acorn.c:356
 check_partition block/partitions/core.c:143 [inline]
 blk_add_partitions block/partitions/core.c:591 [inline]
 bdev_disk_changed+0x817/0x1770 block/partitions/core.c:695
 blkdev_get_whole+0x380/0x510 block/bdev.c:756
 bdev_open+0x31e/0xd30 block/bdev.c:965
 blkdev_open+0x470/0x610 block/fops.c:697
 do_dentry_open+0x785/0x14e0 fs/open.c:947
 vfs_open+0x3b/0x340 fs/open.c:1079
 do_open fs/namei.c:4699 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4858
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 do_sys_openat2+0x113/0x200 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fefe92a7407
RSP: 002b:00007ffd88baac60 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fefe9969880 RCX: 00007fefe92a7407
RDX: 00000000000a0800 RSI: 0000558e7e94e920 RDI: ffffffffffffff9c
RBP: 0000558e7e926910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000558e7e93b830
R13: 0000558e7e934190 R14: 0000000000000000 R15: 0000558e7e93b830
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e95d020 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e95d020 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8e95d020 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5578:
 #0: ffff8880372270a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0 drivers/tty/n_tty.c:2211
3 locks held by udevd/19130:
 #0: ffff888026ea9350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:953
 #1: ffff88801ff11d18 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #1: ffff88801ff11d18 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #1: ffff88801ff11d18 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x31f/0x4f0 block/blk-mq.c:2386
 #2: ffff888026f951f8 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc6/0x1100 drivers/block/nbd.c:1199
4 locks held by syz.2.4616/24788:
 #0: ffffffff8fdc01c8 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:575
 #1: ffffffff8fdceac0 (rtnl_mutex){+.+.}-{4:4}, at: ops_exit_rtnl_list net/core/net_namespace.c:173 [inline]
 #1: ffffffff8fdceac0 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x2a4/0x940 net/core/net_namespace.c:248
 #2: ffffffff8e963328 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
 #2: ffffffff8e963328 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770 kernel/rcu/tree_exp.h:961
 #3: ffff8880b873aea0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:647

=============================================

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 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [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:346 [inline]
 watchdog+0xfaa/0x1000 kernel/hung_task.c:515
 kthread+0x388/0x470 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
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6462 Comm: kworker/u8:14 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
RIP: 0010:__lock_acquire+0x2b4/0x2cf0 kernel/locking/lockdep.c:5170
Code: 90 0b 00 00 83 fd 31 48 89 74 24 18 0f 83 14 28 00 00 48 89 6c 24 28 48 8d 04 ad 00 00 00 00 48 01 e8 89 f1 81 e1 ff 1f 00 00 <ba> 00 e0 ff ff 41 23 54 c7 20 09 ca 41 89 54 c7 20 4d 89 44 c7 08
RSP: 0018:ffffc90006fe76f8 EFLAGS: 00000002
RAX: 000000000000000f RBX: 0000000000000000 RCX: 0000000000000007
RDX: 0000000000000003 RSI: 0000000000000007 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff8b7a114a R09: ffffffff8e95d020
R10: dffffc0000000000 R11: ffffed100fb9b017 R12: 0000000000000000
R13: 0000000000000002 R14: ffff8880567a0000 R15: ffff8880567a0b90
FS:  0000000000000000(0000) GS:ffff888125245000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efe751e7158 CR3: 0000000074ea2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:764 [inline]
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:836 [inline]
 batadv_iv_ogm_schedule+0x45e/0xf50 net/batman-adv/bat_iv_ogm.c:876
 batadv_iv_send_outstanding_bat_ogm_packet+0x6c8/0x7e0 net/batman-adv/bat_iv_ogm.c:1712
 process_one_work kernel/workqueue.c:3288 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3371
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3452
 kthread+0x388/0x470 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
 </TASK>