INFO: task kworker/u8:4:66 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:4    state:D stack:19432 pid:66    tgid:66    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5520 [inline]
 __schedule+0x16d9/0x5700 kernel/sched/core.c:7270
 __schedule_loop kernel/sched/core.c:7347 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7643
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1670 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
 __rt_mutex_slowlock_locked+0x1f88/0x25b0 kernel/locking/rtmutex.c:1787
 rt_mutex_slowlock+0xbd/0x180 kernel/locking/rtmutex.c:1827
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 rwbase_write_lock+0x14c/0x720 kernel/locking/rwbase_rt.c:251
 f2fs_down_write fs/f2fs/f2fs.h:2469 [inline]
 f2fs_down_write_trace+0x34/0x1f0 fs/f2fs/checkpoint.c:181
 f2fs_issue_checkpoint+0x414/0x6f0 fs/f2fs/checkpoint.c:2206
 f2fs_balance_fs_bg+0x571/0x9d0 fs/f2fs/segment.c:553
 f2fs_write_node_pages+0x158/0x700 fs/f2fs/node.c:2283
 do_writepages+0x338/0x560 mm/page-writeback.c:2560
 __writeback_single_inode+0x136/0x1230 fs/fs-writeback.c:1788
 writeback_sb_inodes+0x9db/0x1ab0 fs/fs-writeback.c:2099
 __writeback_inodes_wb+0x114/0x240 fs/fs-writeback.c:2175
 wb_writeback+0x42f/0xad0 fs/fs-writeback.c:2286
 wb_check_old_data_flush fs/fs-writeback.c:2390 [inline]
 wb_do_writeback fs/fs-writeback.c:2469 [inline]
 wb_workfn+0xc98/0x10f0 fs/fs-writeback.c:2497
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
 kthread+0x38b/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>

Showing all locks held in the system:
locks held by kworker/u8:0/12: 3, on CPU#1:
 #0: ffff888032d56938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff888032d56938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff888032d56938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff888032d56938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc90000117c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90000117c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90000117c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc90000117c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline]
 #2: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x123/0x16e0 net/ipv6/addrconf.c:4230
locks held by kworker/u8:1/13: 2, last CPU#0:
 #0: ffff888033891138 ((wq_completion)bat_events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff888033891138 ((wq_completion)bat_events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff888033891138 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff888033891138 ((wq_completion)bat_events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc90000127c40 ((work_completion)(&(&bat_priv->dat.work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90000127c40 ((work_completion)(&(&bat_priv->dat.work)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90000127c40 ((work_completion)(&(&bat_priv->dat.work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc90000127c40 ((work_completion)(&(&bat_priv->dat.work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
locks held by pr/ttyS0/17: 3, last CPU#1:
 #0: ffffffff8e09d578 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline]
 #0: ffffffff8e09d578 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline]
 #0: ffffffff8e09d578 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291
 #1: ffffffff99e981f8 (&port_lock_key){+.+.}-{3:3}, at: nbcon_emit_one kernel/printk/nbcon.c:1137 [inline]
 #1: ffffffff99e981f8 (&port_lock_key){+.+.}-{3:3}, at: nbcon_kthread_func+0x64c/0x880 kernel/printk/nbcon.c:1271
 #2: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #2: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #2: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
locks held by khungtaskd/38: 1, last CPU#0:
 #0: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6837
locks held by kworker/u8:3/56: 7, last CPU#0:
 #0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc9000122fc40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc9000122fc40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc9000122fc40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc9000122fc40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffffffff8f5c3460 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810 net/core/net_namespace.c:677
 #3: ffff88804cca9160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #3: ffff88804cca9160 (&dev->mutex){....}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:124 [inline]
 #3: ffff88804cca9160 (&dev->mutex){....}-{4:4}, at: devlink_pernet_pre_exit+0x129/0x420 net/devlink/core.c:575
 #4: ffff888033c7a310 (&devlink->lock_key#58){+.+.}-{4:4}, at: devl_lock net/devlink/core.c:308 [inline]
 #4: ffff888033c7a310 (&devlink->lock_key#58){+.+.}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:125 [inline]
 #4: ffff888033c7a310 (&devlink->lock_key#58){+.+.}-{4:4}, at: devlink_pernet_pre_exit+0x142/0x420 net/devlink/core.c:575
 #5: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: nsim_destroy+0x173/0x800 drivers/net/netdevsim/netdev.c:1193
 #6: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #6: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #6: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: __fib6_clean_all+0xb8/0x620 net/ipv6/ip6_fib.c:2319
locks held by kworker/u8:4/66: 4, on CPU#1:
 #0: ffff88801d694138 ((wq_completion)writeback){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88801d694138 ((wq_completion)writeback){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88801d694138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88801d694138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc9000151fc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc9000151fc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc9000151fc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc9000151fc40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffff888033aea0e0 (&type->s_umount_key#81){++++}-{4:4}, at: super_trylock_shared+0x23/0xf0 fs/super.c:688
 #3: ffff88802ac71ab0 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2469 [inline]
 #3: ffff88802ac71ab0 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write_trace+0x34/0x1f0 fs/f2fs/checkpoint.c:181
locks held by kworker/u8:10/1032: 3, on CPU#1:
 #0: ffff88813ff64138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88813ff64138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88813ff64138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88813ff64138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc9000663fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc9000663fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc9000663fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc9000663fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313
locks held by klogd/4938: 1, last CPU#0:
 #0: ffffffff8e310fb0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:198 [inline]
 #0: ffffffff8e310fb0 (remove_cache_srcu){.+.+}-{0:0}, at: srcu_read_lock+0x27/0x60 include/linux/srcu.h:305
locks held by dhcpcd/5244: 2, on CPU#1:
 #0: ffff88802b92c928 (nlk_cb_mutex-ROUTE){+.+.}-{4:4}, at: __netlink_dump_start+0xf4/0x7b0 net/netlink/af_netlink.c:2410
 #1: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dump_ifinfo+0xa74/0x14b0 net/core/rtnetlink.c:2613
locks held by getty/5340: 2, on CPU#0:
 #0: ffff888025c490a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900044cb2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x460/0x1360 drivers/tty/n_tty.c:2211
locks held by kworker/1:5/5713: 3, on CPU#1:
 #0: ffff88813ff27938 ((wq_completion)events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88813ff27938 ((wq_completion)events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88813ff27938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88813ff27938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc90006317c40 (deferred_process_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc90006317c40 (deferred_process_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc90006317c40 (deferred_process_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc90006317c40 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104
locks held by kworker/0:9/11114: 2, last CPU#0:
 #0: ffff88813ff26538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88813ff26538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88813ff26538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88813ff26538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc900049c7c40 ((work_completion)(&(&tbl->gc_work)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc900049c7c40 ((work_completion)(&(&tbl->gc_work)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc900049c7c40 ((work_completion)(&(&tbl->gc_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc900049c7c40 ((work_completion)(&(&tbl->gc_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
locks held by syz.0.533/12260: 4, last CPU#0:
 #0: ffff888033aea510 (sb_writers#23){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x210 fs/namespace.c:538
 #1: ffff88802ac71ab0 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2469 [inline]
 #1: ffff88802ac71ab0 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write_trace+0x34/0x1f0 fs/f2fs/checkpoint.c:181
 #2: ffff88802ac70350 (&sbi->cp_global_sem_key){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2469 [inline]
 #2: ffff88802ac70350 (&sbi->cp_global_sem_key){+.+.}-{4:4}, at: f2fs_down_write_trace+0x34/0x1f0 fs/f2fs/checkpoint.c:181
 #3: ffff8880b863c320 (&rq->__lock){-...}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160 kernel/sched/core.c:677
locks held by syz-executor/13345: 6, last CPU#1:
 #0: ffff8880717160e0 (&type->s_umount_key#70){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff8880717160e0 (&type->s_umount_key#70){++++}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
 #0: ffff8880717160e0 (&type->s_umount_key#70){++++}-{4:4}, at: deactivate_super+0xac/0xe0 fs/super.c:631
 #1: ffff888034582190 (&journal->j_barrier){+.+.}-{4:4}, at: jbd2_journal_lock_updates+0x2d1/0x370 fs/jbd2/transaction.c:886
 #2: ffff888034582588 (&journal->j_checkpoint_mutex){+.+.}-{4:4}, at: jbd2_journal_flush+0x28c/0xd40 fs/jbd2/journal.c:2438
 #3: ffff888034582108 (&journal->j_state_lock){++++}-{3:3}, at: read_lock include/linux/rwlock_rt.h:38 [inline]
 #3: ffff888034582108 (&journal->j_state_lock){++++}-{3:3}, at: jbd2_journal_get_log_tail+0x3b/0x360 fs/jbd2/journal.c:1022
 #4: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #4: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #4: ffffffff8e1c3ac0 (rcu_read_lock){....}-{1:3}, at: rt_read_lock+0x279/0x4b0 kernel/locking/spinlock_rt.c:251
 #5: ffff888034582920 (&journal->j_list_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #5: ffff888034582920 (&journal->j_list_lock){+.+.}-{3:3}, at: jbd2_journal_get_log_tail+0x4b/0x360 fs/jbd2/journal.c:1023
locks held by syz-executor/13537: 1, on CPU#1:
 #0: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline]
 #0: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: inet6_rtm_newaddr+0x667/0xe00 net/ipv6/addrconf.c:5063
locks held by syz-executor/13639: 7, on CPU#1:
 #0: ffff888036468510 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
 #0: ffff888036468510 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
 #1: ffff88805fe9fc78 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d9/0x540 fs/kernfs/file.c:336
 #2: ffff888029bc5e18 (kn->active#52){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #2: ffff888029bc5e18 (kn->active#52){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22c/0x540 fs/kernfs/file.c:337
 #3: ffffffff8ee42938 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: new_device_store+0x13c/0x6d0 drivers/net/netdevsim/bus.c:184
 #4: ffff88803a6e6160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #4: ffff88803a6e6160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
 #5: ffff8880656aa310 (&devlink->lock_key#60){+.+.}-{4:4}, at: nsim_drv_probe+0xfb/0xbc0 drivers/net/netdevsim/dev.c:1583
 #6: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:134 [inline]
 #6: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2128
locks held by syz-executor/13787: 2, on CPU#1:
 #0: ffffffff8ed31a48 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8ed31a48 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8ed31a48 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:595
 #1: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:366 [inline]
 #1: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xc10/0x1c30 net/core/rtnetlink.c:4214
locks held by syz-executor/13828: 2, on CPU#1:
 #0: ffffffff8f5c3460 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x524/0x780 net/core/net_namespace.c:578
 #1: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock_killable include/linux/rtnetlink.h:149 [inline]
 #1: ffffffff8f5d1cb8 (rtnl_mutex){+.+.}-{4:4}, at: register_netdev+0x18/0x60 net/core/dev.c:11617

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 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/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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 17 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT_{RT,(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 ce cc 65 fc 44 89 f9 d3 e3 49 83 ee 80 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 6f 7b d1 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:ffffc900001678b8 EFLAGS: 00000202
RAX: 1ffffffff33d3000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff8560aca0 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff99e98220 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125cd5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cab330b450 CR3: 0000000061ac2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:128 [inline]
 serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
 wait_for_lsr+0x190/0x300 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+0x34f/0x3f0 drivers/tty/serial/8250/8250_port.c:3372
 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+0xac5/0x1230 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/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>