[v6.1] INFO: task hung in lock_sock_nested

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f2ddafa93a25 Linux 6.1.166
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=132f78d6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1adc0bfde2d8a4a
dashboard link: https://syzkaller.appspot.com/bug?extid=0bb1f3d36dfd646beeab
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/28fc2cbac5cf/disk-f2ddafa9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b17a5a214fbc/vmlinux-f2ddafa9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c2564b1203e5/Image-f2ddafa9.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0bb1f3...@syzkaller.appspotmail.com

INFO: task syz.0.420:6135 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.420 state:D stack:0 pid:6135 ppid:4325 flags:0x00000009
Call trace:
__switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555
context_switch kernel/sched/core.c:5245 [inline]
__schedule+0xdd0/0x1b0c kernel/sched/core.c:6562
schedule+0xc4/0x170 kernel/sched/core.c:6638
__lock_sock+0x10c/0x264 net/core/sock.c:2920
lock_sock_nested+0xb8/0x130 net/core/sock.c:3501
lock_sock include/net/sock.h:1805 [inline]
tipc_send_group_bcast+0x464/0xacc net/tipc/socket.c:1100
__tipc_sendmsg+0x2ac/0x28b8 net/tipc/socket.c:1436
tipc_sendmsg+0x60/0x1bc net/tipc/socket.c:1403
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
sock_write_iter+0x268/0x360 net/socket.c:1143
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x3ec/0x7f0 fs/read_write.c:584
ksys_write+0x12c/0x224 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffff8000153e7c30 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffff8000153e8450 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
#0: ffff8000153e72c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
2 locks held by kworker/1:2/112:
#0: ffff0000c0021938 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x6b8/0x13a4 kernel/workqueue.c:2265
#1: ffff8000205b7c20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x6fc/0x13a4 kernel/workqueue.c:2267
2 locks held by getty/4078:
#0: ffff0000d656e098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
#1: ffff8000207eb2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2ec/0xfa0 drivers/tty/n_tty.c:2198
3 locks held by kworker/1:11/5727:
#0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x6b8/0x13a4 kernel/workqueue.c:2265
#1: ffff800022477c20 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x6fc/0x13a4 kernel/workqueue.c:2267
#2: ffff0000cc19b240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x1d0/0x27cc drivers/net/netdevsim/fib.c:1491
2 locks held by kworker/u4:16/5872:
#0: ffff0000c0029138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x6b8/0x13a4 kernel/workqueue.c:2265
#1: ffff8000217b7c20 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work+0x6fc/0x13a4 kernel/workqueue.c:2267
1 lock held by syz.0.420/6134:
1 lock held by syz.0.420/6135:
#0: ffff0000d248dc30 (sk_lock-AF_TIPC){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1805 [inline]
#0: ffff0000d248dc30 (sk_lock-AF_TIPC){+.+.}-{0:0}, at: tipc_send_group_bcast+0x464/0xacc net/tipc/socket.c:1100
1 lock held by syz-executor/6387:
#0: ffff8000153ecf78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
#0: ffff8000153ecf78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2b8/0x77c kernel/rcu/tree_exp.h:962
3 locks held by kworker/u4:20/8978:
1 lock held by syz.3.1159/9154:
1 lock held by syz.4.1161/9161:
#0: ffff8000153ecf78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
#0: ffff8000153ecf78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3fc/0x77c kernel/rcu/tree_exp.h:962
2 locks held by syz.2.1163/9168:
#0: ffff8000178db290 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff8000153ece40 (rcu_state.barrier_mutex){+.+.}-{3:3}, at: rcu_barrier+0x58/0x5d0 kernel/rcu/tree.c:4023

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