[syzbot] [net?] INFO: task hung in svc_listen (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aaec7096f996 net: hsr: defer node table free until after R..
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=10fe2536580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4caf64b1ee83dac0
dashboard link: https://syzkaller.appspot.com/bug?extid=3febffd6d2ea432770c6
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10bdd02e580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13a5e02e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2e91c83cade4/disk-aaec7096.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8ec0ff6fa021/vmlinux-aaec7096.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b593c2df20a5/bzImage-aaec7096.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3febff...@syzkaller.appspotmail.com

INFO: task syz.4.342:7421 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.342 state:D stack:27032 pid:7421 tgid:7420 ppid:5800 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x1821/0x5740 kernel/sched/core.c:7189
__schedule_loop kernel/sched/core.c:7268 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7283
svc_listen+0x2c3/0x500 net/atm/svc.c:311
__sys_listen_socket net/socket.c:1987 [inline]
__sys_listen net/socket.c:2002 [inline]
__do_sys_listen net/socket.c:2007 [inline]
__se_sys_listen net/socket.c:2005 [inline]
__x64_sys_listen+0x1c7/0x240 net/socket.c:2005
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: 0033:0x7fa947d9ce59
RSP: 002b:00007fa948b90028 EFLAGS: 00000246 ORIG_RAX: 0000000000000032
RAX: ffffffffffffffda RBX: 00007fa948015fa0 RCX: 00007fa947d9ce59
RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000004
RBP: 00007fa947e32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa948016038 R14: 00007fa948015fa0 R15: 00007ffdf1c6c548
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
6 locks held by kworker/u8:3/48:
5 locks held by kworker/u8:7/153:
#0: ffff8880b873aea0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:652
#1: ffff8880b8724588 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880 kernel/sched/psi.c:933
#2: ffff8880b8726118 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x8ee/0xf30 kernel/time/timer.c:1117
#3: ffffffff9a6b8cf0 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x83/0x580 lib/debugobjects.c:835
#4: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#4: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#4: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
#4: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xa6/0x2550 arch/x86/kernel/unwind_orc.c:495
8 locks held by kworker/u8:9/3273:
2 locks held by getty/5386:
#0: ffff888032a2e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0 drivers/tty/n_tty.c:2211
1 lock held by syz.4.342/7421:
#0: ffff8880349b6260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff8880349b6260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: svc_listen+0x13f/0x500 net/atm/svc.c:295
1 lock held by syz.1.414/7744:
#0: ffff8880222c7260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff8880222c7260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: svc_listen+0x13f/0x500 net/atm/svc.c:295
1 lock held by syz.3.611/8709:
#0: ffff88807cccf260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff88807cccf260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: svc_listen+0x13f/0x500 net/atm/svc.c:295
1 lock held by syz.6.637/8830:
#0: ffff88801bbae260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff88801bbae260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: svc_listen+0x13f/0x500 net/atm/svc.c:295
1 lock held by syz.0.742/9319:
#0: ffff88802a79a260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff88802a79a260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: svc_listen+0x13f/0x500 net/atm/svc.c:295
1 lock held by syz.9.990/10528:
#0: ffff8880352ba260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff8880352ba260 (sk_lock-AF_ATMSVC){+.+.}-{0:0}, at: svc_listen+0x13f/0x500 net/atm/svc.c:295
2 locks held by syz.2.1305/11970:
#0: ffffffff8fdc1568 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:575
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: ops_exit_rtnl_list net/core/net_namespace.c:173 [inline]
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x2a4/0x940 net/core/net_namespace.c:248
2 locks held by syz.7.1304/11974:
#0: ffffffff8fdc1568 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:575
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: ops_exit_rtnl_list net/core/net_namespace.c:173 [inline]
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x2a4/0x940 net/core/net_namespace.c:248
2 locks held by syz.8.1307/11978:
#0: ffffffff8fdc1568 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:575
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: ops_exit_rtnl_list net/core/net_namespace.c:173 [inline]
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x2a4/0x940 net/core/net_namespace.c:248
2 locks held by syz.5.1308/11983:
#0: ffffffff8fdc1568 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:575
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: ip_tunnel_init_net+0x2d7/0x840 net/ipv4/ip_tunnel.c:1146
2 locks held by syz.4.1309/11988:
#0: ffffffff8fdc1568 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x4f7/0x730 net/core/net_namespace.c:575
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#1: ffffffff8fdd0240 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2102

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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:162 [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+0xfd3/0x1030 kernel/hung_task.c:561
kthread+0x389/0x470 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: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: 9b 7d 02 e9 93 f7 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 91 20 00 fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e20 EFLAGS: 00000246
RAX: 00000000001162af RBX: ffffffff819a958a RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8dfa6c27 RDI: ffffffff8c28af60
RBP: ffffc90000197f10 R08: ffff8880b87339db R09: 1ffff110170e673b
R10: dffffc0000000000 R11: ffffed10170e673c R12: 0000000000000001
R13: 1ffff11003b5b000 R14: 0000000000000001 R15: 1ffff11003b5b000
FS: 0000000000000000(0000) GS:ffff88812538a000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34a24224 CR3: 0000000078488000 CR4: 00000000003526f0
Call Trace:
<TASK>
arch_safe_halt arch/x86/kernel/process.c:766 [inline]
default_idle+0x9/0x20 arch/x86/kernel/process.c:767
default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:199 [inline]
do_idle+0x36a/0x5f0 kernel/sched/idle.c:352
cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451
start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
common_startup_64+0x13e/0x147
</TASK>


---
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