INFO: task rcu_tasks_kthre:12 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:rcu_tasks_kthre state:D stack:27920 pid:12    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2144
 do_wait_for_common kernel/sched/completion.c:85 [inline]
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x2c2/0x590 kernel/sched/completion.c:138
 __synchronize_srcu+0x2b3/0x350 kernel/rcu/srcutree.c:1243
 rcu_tasks_wait_gp+0x49f/0xac0 kernel/rcu/tasks.h:693
 rcu_tasks_one_gp+0xd27/0xef0 kernel/rcu/tasks.h:534
 rcu_tasks_kthread+0x6e/0x90 kernel/rcu/tasks.h:562
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2e230 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2ea50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8cb2d8a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2d8a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2d8a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6669
1 lock held by dhcpcd/3933:
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163
2 locks held by getty/4029:
 #0: ffff88802fc91098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
3 locks held by kworker/u4:5/4323:
 #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90004457d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
2 locks held by kworker/0:4/4340:
 #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90004547d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
4 locks held by kworker/u4:38/8213:
 #0: ffff88801761e938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc9000da87d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd49ed0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x148/0xba0 net/core/net_namespace.c:594
 #3: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: ip_tunnel_delete_nets+0xd2/0x370 net/ipv4/ip_tunnel.c:1152
3 locks held by syz.2.3667/20401:
2 locks held by syz.2.3680/20450:
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3506
 #1: ffffffff8cb33578 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
 #1: ffffffff8cb33578 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2ec/0x890 kernel/rcu/tree_exp.h:962
1 lock held by syz.1.3684/20463:
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3506
1 lock held by syz.1.3684/20467:
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x54d/0xe80 net/core/dev_ioctl.c:571
1 lock held by syz.0.3685/20465:
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3506
1 lock held by syz.0.3685/20469:
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: dev_ioctl+0x54d/0xe80 net/core/dev_ioctl.c:571
2 locks held by syz.5.3687/20484:
 #0: ffffffff8dd49ed0 (pernet_ops_rwsem){++++}-{3:3}, at: copy_net_ns+0x324/0x5b0 net/core/net_namespace.c:504
 #1: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: register_nexthop_notifier+0x84/0x240 net/ipv4/nexthop.c:3619
1 lock held by syz.4.3689/20491:
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3506
1 lock held by syz.4.3689/20492:
 #0: ffffffff8dd56d68 (rtnl_mutex){+.+.}-{3:3}, at: dev_ethtool+0x1de/0x12f0 net/ethtool/ioctl.c:3094

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3620 Comm: syslogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:memset+0x1e/0x40 mm/kasan/shadow.c:44
Code: 0c 24 ba 01 00 00 00 e9 b0 ec ff ff 55 41 56 53 48 89 d3 89 f5 49 89 fe 48 8b 4c 24 18 48 89 d6 ba 01 00 00 00 e8 92 ec ff ff <84> c0 74 11 4c 89 f7 89 ee 48 89 da 5b 41 5e 5d e9 7d 4a 54 08 31
RSP: 0018:ffffc90003297480 EFLAGS: 00000256
RAX: 0000000000000001 RBX: 0000000000000010 RCX: ffffffff8139037a
RDX: 0000000000000001 RSI: 0000000000000010 RDI: ffffc90003297598
RBP: 0000000000000000 R08: ffffc900032975a7 R09: 1ffff92000652eb4
R10: dffffc0000000000 R11: fffff52000652eb5 R12: dffffc0000000000
R13: ffffc90003298000 R14: ffffc90003297598 R15: ffffc9000329757d
FS:  00007ff3dbec3c80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555823ed4e8 CR3: 000000007e44c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 unwind_next_frame+0x8da/0x1fd0 arch/x86/kernel/unwind_orc.c:546
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x200 mm/slub.c:3700
 skb_free_head net/core/skbuff.c:762 [inline]
 skb_release_data+0x5e9/0x7e0 net/core/skbuff.c:791
 skb_release_all net/core/skbuff.c:856 [inline]
 __kfree_skb net/core/skbuff.c:870 [inline]
 consume_skb+0xa2/0x100 net/core/skbuff.c:1038
 __unix_dgram_recvmsg+0xa04/0xda0 net/unix/af_unix.c:2543
 sock_recvmsg_nosec net/socket.c:1023 [inline]
 sock_recvmsg net/socket.c:1041 [inline]
 sock_read_iter+0x2da/0x3a0 net/socket.c:1122
 call_read_iter include/linux/fs.h:2265 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x471/0x960 fs/read_write.c:470
 ksys_read+0x14d/0x260 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff3dc013407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffc96995200 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ff3dbec3c80 RCX: 00007ff3dc013407
RDX: 00000000000000ff RSI: 0000557d87104950 RDI: 0000000000000000
RBP: 0000557d87104910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000557d8710499b
R13: 0000000000000000 R14: 0000557d87104950 R15: 0000557d57436d98
 </TASK>