syzbot

INFO: task syz.2.930:10685 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.930       state:D stack:26520 pid:10685 tgid:10680 ppid:5631   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1295/0x67a0 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7283
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7340
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xced/0x1b10 kernel/locking/mutex.c:820
 nfsd_nl_version_get_doit+0x18c/0x7f0 fs/nfsd/nfsctl.c:1873
 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2555
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752
 __sys_sendmsg+0x170/0x220 net/socket.c:2784
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd18d59ce59
RSP: 002b:00007fd18b7d5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd18d816090 RCX: 00007fd18d59ce59
RDX: 0000000000008010 RSI: 0000200000000100 RDI: 0000000000000007
RBP: 00007fd18d632d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd18d816128 R14: 00007fd18d816090 R15: 00007ffe5fb122b8
 </TASK>
INFO: task syz.3.937:10724 blocked for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.937       state:D stack:27192 pid:10724 tgid:10723 ppid:5632   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1295/0x67a0 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7283
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7340
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xced/0x1b10 kernel/locking/mutex.c:820
 nfsd_nl_listener_set_doit+0xd5/0x1a80 fs/nfsd/nfsctl.c:1948
 genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
 genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2555
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752
 __sys_sendmsg+0x170/0x220 net/socket.c:2784
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3fe1b9ce59
RSP: 002b:00007f3fdfdee028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f3fe1e15fa0 RCX: 00007f3fe1b9ce59
RDX: 0000000000048080 RSI: 0000200000003140 RDI: 0000000000000003
RBP: 00007f3fe1c32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3fe1e16038 R14: 00007f3fe1e15fa0 R15: 00007fff3c4e7588
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e7e5420 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e7e5420 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8e7e5420 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
4 locks held by kworker/u10:7/6696:
 #0: ffff88801c6a6140 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3289
 #1: ffffc900050dfd08 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3290
 #2: ffffffff905ecec8 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xb8/0x920 net/core/net_namespace.c:673
 #3: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: cangw_pernet_exit_batch+0x15/0xa0 net/can/gw.c:1294
3 locks held by kworker/u10:19/9642:
 #0: ffff888032a04940 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3289
 #1: ffffc9000512fd08 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3290
 #2: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4746
3 locks held by kworker/u10:21/9644:
 #0: ffff88813fe94140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3289
 #1: ffffc9000519fd08 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3290
 #2: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0x51/0xc0 net/core/link_watch.c:313
2 locks held by syz.1.892/10494:
 #0: ffffffff906b4088 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1a80 fs/nfsd/nfsctl.c:1948
2 locks held by syz.2.930/10685:
 #0: ffffffff906b4088 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x18c/0x7f0 fs/nfsd/nfsctl.c:1873
2 locks held by syz-executor/10722:
 #0: ffff888025cdc0d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff888025cdc0d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff888025cdc0d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
 #0: ffff888025cdc0d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz.3.937/10724:
 #0: ffffffff906b4088 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1a80 fs/nfsd/nfsctl.c:1948
2 locks held by syz-executor/10910:
 #0: ffff88802a5360d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802a5360d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff88802a5360d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
 #0: ffff88802a5360d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz.7.1034/11413:
 #0: ffffffff906b4088 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1a80 fs/nfsd/nfsctl.c:1948
2 locks held by syz-executor/11563:
 #0: ffff888059c160d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff888059c160d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff888059c160d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
 #0: ffff888059c160d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz-executor/11626:
 #0: ffff88802b39a0d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88802b39a0d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff88802b39a0d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
 #0: ffff88802b39a0d8 (&type->s_umount_key#55){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz.0.1070/11633:
 #0: ffffffff906b4088 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1a80 fs/nfsd/nfsctl.c:1948
1 lock held by syz-executor/11829:
 #0: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3441
2 locks held by syz.6.1131/12021:
 #0: ffffffff906b4088 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec622a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x8c8/0x1100 fs/nfsd/nfsctl.c:1644
2 locks held by syz-executor/12248:
 #0: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3441
 #1: ffffffff8e7f0f68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
1 lock held by syz-executor/12287:
 #0: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3441
1 lock held by syz-executor/12438:
 #0: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff90605c20 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3441

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 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+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xcb1/0x1030 kernel/hung_task.c:561
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>