INFO: task syz.1.1000:11237 blocked for more than 143 seconds.
      Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0
      Blocked by coredump.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1000      state:D stack:26072 pid:11237 tgid:11237 ppid:10467  task_flags:0x40044c flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x1b18/0x50e0 kernel/sched/core.c:6748
 __schedule_loop kernel/sched/core.c:6825 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6840
 wb_wait_for_completion+0x166/0x270 fs/fs-writeback.c:216
 sync_inodes_sb+0x28f/0xb50 fs/fs-writeback.c:2821
 sync_filesystem+0x176/0x230 fs/sync.c:64
 generic_shutdown_super+0x72/0x2d0 fs/super.c:621
 kill_block_super+0x44/0x90 fs/super.c:1710
 ext4_kill_sb+0x68/0xa0 fs/ext4/super.c:7368
 deactivate_locked_super+0xc6/0x130 fs/super.c:473
 cleanup_mnt+0x422/0x4c0 fs/namespace.c:1435
 task_work_run+0x253/0x310 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xa2a/0x2940 kernel/exit.c:954
 do_group_exit+0x207/0x2c0 kernel/exit.c:1103
 get_signal+0x1696/0x1730 kernel/signal.c:3035
 arch_do_signal_or_restart+0x98/0x840 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xce/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbd783bfa25
RSP: 002b:00007fbd761d4f80 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 00007fbd785a6080 RCX: 00007fbd783bfa25
RDX: 00007fbd761d4fc0 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fbd7840e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fbd785a6080 R15: 00007ffdd6445618
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/u8:1/13:
 #0: ffff88801baee148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801baee148 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc90000127c60 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000127c60 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
 #2: ffffffff8fec98d0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0x17c/0xd60 net/core/net_namespace.c:606
 #3: ffff8880128d14e8 (&wg->device_update_lock){+.+.}-{4:4}, at: wg_destruct+0x110/0x2e0 drivers/net/wireguard/device.c:249
 #4: ffff8880b8639ad8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:595
1 lock held by khungtaskd/31:
 #0: ffffffff8eb3a760 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8eb3a760 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8eb3a760 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x30/0x180 kernel/locking/lockdep.c:6761
2 locks held by kworker/u8:5/1097:
3 locks held by kworker/u8:8/1146:
2 locks held by dhcpcd/5496:
 #0: ffffffff8febb028 (vlan_ioctl_mutex){+.+.}-{4:4}, at: sock_ioctl+0x68a/0x900 net/socket.c:1280
 #1: ffffffff8fed6108 (rtnl_mutex){+.+.}-{4:4}, at: vlan_ioctl_handler+0x118/0xa20 net/8021q/vlan.c:554
2 locks held by getty/5587:
 #0: ffff888030e9e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fd62f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x53d/0x16b0 drivers/tty/n_tty.c:2211
3 locks held by kworker/u8:12/8649:
 #0: ffff88814d3ea948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88814d3ea948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc90003c57c60 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90003c57c60 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
 #2: ffffffff8fed6108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:129 [inline]
 #2: ffffffff8fed6108 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x110/0x16a0 net/ipv6/addrconf.c:4190
1 lock held by syz-executor/10230:
 #0: ffffffff8eb3fc78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #0: ffffffff8eb3fc78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x454/0x830 kernel/rcu/tree_exp.h:998
2 locks held by syz.1.1000/11237:
 #0: ffff88805aba60e0 (&type->s_umount_key#31){++++}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88805aba60e0 (&type->s_umount_key#31){++++}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88805aba60e0 (&type->s_umount_key#31){++++}-{4:4}, at: deactivate_super+0xb5/0xf0 fs/super.c:505
 #1: ffff8881437627d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
 #1: ffff8881437627d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x270/0xb50 fs/fs-writeback.c:2819
3 locks held by syz-executor/13179:
 #0: ffffffff8fed6108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:79 [inline]
 #0: ffffffff8fed6108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:335 [inline]
 #0: ffffffff8fed6108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xd6a/0x1f60 net/core/rtnetlink.c:4021
 #1: ffff88807b7354e8 (&wg->device_update_lock){+.+.}-{4:4}, at: wg_open+0x22d/0x420 drivers/net/wireguard/device.c:50
 #2: ffffffff8eb3fc78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #2: ffffffff8eb3fc78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x454/0x830 kernel/rcu/tree_exp.h:998
1 lock held by syz-executor/13251:
 #0: ffffffff8fed6108 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:129 [inline]
 #0: ffffffff8fed6108 (rtnl_mutex){+.+.}-{4:4}, at: inet6_rtm_newaddr+0x7da/0xf40 net/ipv6/addrconf.c:5023
1 lock held by syz.2.1390/13972:
 #0: ffff888011f35c08 (&sb->s_type->i_mutex_key#10){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline]
 #0: ffff888011f35c08 (&sb->s_type->i_mutex_key#10){+.+.}-{4:4}, at: __sock_release net/socket.c:646 [inline]
 #0: ffff888011f35c08 (&sb->s_type->i_mutex_key#10){+.+.}-{4:4}, at: sock_close+0x90/0x240 net/socket.c:1398
1 lock held by syz.2.1390/13996:
 #0: ffff88807d918420 (sb_writers#16){.+.+}-{0:0}, at: direct_splice_actor+0x49/0x220 fs/splice.c:1157

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x4ab/0x4e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline]
 watchdog+0x1058/0x10a0 kernel/hung_task.c:399
 kthread+0x7ab/0x920 kernel/kthread.c:464
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:153
 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: 13251 Comm: syz-executor Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:get_data+0x468/0x880 kernel/printk/printk_ringbuffer.c:1256
Code: 07 48 83 e3 f8 48 89 ef 48 89 de e8 42 1b 20 00 48 39 dd 0f 85 a6 00 00 00 4c 89 e0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 e7 e8 ba 37 88 00 49 8b 1c 24 48 8d 6b 07
RSP: 0018:ffffc9000d7061f8 EFLAGS: 00000212
RAX: 1ffff92001ae0c70 RBX: 00000000000710b8 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 00000000000710b8 RDI: 00000000000710b8
RBP: 00000000000710b8 R08: ffffffff81a349ee R09: 1ffff92001ae0cc2
R10: dffffc0000000000 R11: fffff52001ae0cc3 R12: ffffc9000d706380
R13: 0000000000000070 R14: 1ffff92001ae0c68 R15: ffffc9000d706378
FS:  0000555567f4f500(0000) GS:ffff888125324000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557991defe88 CR3: 000000005bfd6000 CR4: 0000000000350ef0
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 copy_data kernel/printk/printk_ringbuffer.c:1827 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1936 [inline]
 _prb_read_valid+0x60d/0xae0 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0xab/0xf0 kernel/printk/printk_ringbuffer.c:2182
 printk_get_next_message+0x1f5/0x8b0 kernel/printk/printk.c:2987
 console_emit_next_record kernel/printk/printk.c:3074 [inline]
 console_flush_all+0x56b/0xec0 kernel/printk/printk.c:3208
 __console_flush_and_unlock kernel/printk/printk.c:3267 [inline]
 console_unlock+0x151/0x3b0 kernel/printk/printk.c:3307
 vprintk_emit+0x732/0xa10 kernel/printk/printk.c:2432
 _printk+0xd5/0x120 kernel/printk/printk.c:2457
 batadv_hardif_activate_interface+0x16e/0x3c0 net/batman-adv/hard-interface.c:675
 batadv_hard_if_event+0x354/0x1810 net/batman-adv/hard-interface.c:977
 notifier_call_chain+0x1a7/0x3f0 kernel/notifier.c:85
 __dev_notify_flags+0x209/0x410
 dev_change_flags+0xf0/0x1a0 net/core/dev.c:9334
 do_setlink+0xc5a/0x4130 net/core/rtnetlink.c:3118
 rtnl_changelink net/core/rtnetlink.c:3733 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3885 [inline]
 rtnl_newlink+0x1945/0x1f60 net/core/rtnetlink.c:4022
 rtnetlink_rcv_msg+0x811/0xd70 net/core/rtnetlink.c:6912
 netlink_rcv_skb+0x20a/0x480 net/netlink/af_netlink.c:2533
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x7fa/0x9a0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x8e8/0xce0 net/netlink/af_netlink.c:1882
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x223/0x270 net/socket.c:733
 __sys_sendto+0x365/0x4c0 net/socket.c:2187
 __do_sys_sendto net/socket.c:2194 [inline]
 __se_sys_sendto net/socket.c:2190 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2190
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3e4a58effc
Code: 2a 5f 02 00 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0 ff ff 77 34 89 ef 48 89 44 24 08 e8 70 5f 02 00 48 8b
RSP: 002b:00007ffd3b9f8720 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f3e4b2d4620 RCX: 00007f3e4a58effc
RDX: 000000000000002c RSI: 00007f3e4b2d4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffd3b9f8774 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f3e4b2d4670 R15: 0000000000000000
 </TASK>