INFO: task syz.6.11292:30061 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.6.11292     state:D stack:28120 pid:30061 tgid:30060 ppid:29876  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x125c/0x6730 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0xdd/0x2c0 kernel/sched/core.c:7326
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
 nfsd_nl_expkey_set_reqs_doit+0x8a/0x2f0 fs/nfsd/export.c:561
 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:2556
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec net/socket.c:775 [inline]
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2738
 __sys_sendmsg+0x160/0x210 net/socket.c:2770
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb32b59de99
RSP: 002b:00007fb32c553028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb32b825fa0 RCX: 00007fb32b59de99
RDX: 0000000004008090 RSI: 0000200000000140 RDI: 0000000000000003
RBP: 00007fb32b633eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb32b826038 R14: 00007fb32b825fa0 R15: 00007ffef83baed8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8ebe8180 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8ebe8180 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8ebe8180 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
1 lock held by klogd/4966:
 #0: ffff8880b853b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x140 kernel/sched/core.c:667
2 locks held by getty/5364:
 #0: ffff8880371aa0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
2 locks held by syz-executor/6078:
 #0: ffff888079a8a0d8 (&type->s_umount_key#88){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff888079a8a0d8 (&type->s_umount_key#88){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff888079a8a0d8 (&type->s_umount_key#88){++++}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
 #0: ffff888079a8a0d8 (&type->s_umount_key#88){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
 #1: ffffffff8f0727a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
3 locks held by kworker/u8:12/11377:
 #0: ffff8880b853b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x140 kernel/sched/core.c:667
 #1: ffff8880b8524568 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:218 [inline]
 #1: ffff8880b8524568 (psi_seq){-.-.}-{0:0}, at: __schedule+0x2e8e/0x6730 kernel/sched/core.c:7228
 #2: ffff8880b8526298 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x124/0x1d0 kernel/time/timer.c:1004
3 locks held by syz.2.11031/29421:
 #0: ffff888026a9b0b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff88804b8d0450 (sb_writers#24){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0727a0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xa5/0xcc0 fs/nfsd/nfsctl.c:860
5 locks held by kworker/u8:0/29688:
 #0: ffff8880b853b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x140 kernel/sched/core.c:667
 #1: ffffc90003f07d08 ((work_completion)(&(&bat_priv->tt.work)->work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
 #2: ffff8880b8526298 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x6e7/0xca0 kernel/time/timer.c:1117
 #3: ffff8880b853b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x140 kernel/sched/core.c:667
 #4: ffff8880b8528418 (hrtimer_bases.lock){-.-.}-{2:2}, at: class_raw_spinlock_constructor include/linux/spinlock.h:535 [inline]
 #4: ffff8880b8528418 (hrtimer_bases.lock){-.-.}-{2:2}, at: __hrtimer_rearm_deferred+0xb9/0x720 kernel/time/hrtimer.c:2153
2 locks held by syz.6.11292/30061:
 #0: ffffffff90b4e428 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8f0727a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_expkey_set_reqs_doit+0x8a/0x2f0 fs/nfsd/export.c:561
3 locks held by syz.5.11861/31419:
 #0: ffff88807928f5f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff88802680a450 (sb_writers#24){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0727a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nrthreads+0x63/0x1d0 fs/nfsd/nfssvc.c:245
3 locks held by syz.1.11911/31526:
 #0: ffff888026c5d430 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff888052f86450 (sb_writers#24){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0727a0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xa5/0xcc0 fs/nfsd/nfsctl.c:860
3 locks held by syz.8.12033/31804:
 #0: ffff8880797fd430 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff88804d608450 (sb_writers#24){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0727a0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd4_write_time fs/nfsd/nfsctl.c:963 [inline]
 #2: ffffffff8f0727a0 (nfsd_mutex){+.+.}-{4:4}, at: write_leasetime+0xa3/0x110 fs/nfsd/nfsctl.c:993
3 locks held by syz.3.12258/32408:
 #0: ffff88807eaab0b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
 #1: ffff888052974450 (sb_writers#24){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
 #2: ffffffff8f0727a0 (nfsd_mutex){+.+.}-{4:4}, at: write_versions+0x9d/0xba0 fs/nfsd/nfsctl.c:701
2 locks held by syz.0.13241/2237:
 #0: ffffffff90a9f740 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline]
 #0: ffffffff90a9f740 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3506
 #1: ffffffff8ebf3c28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
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:122
 nmi_trigger_cpumask_backtrace+0x21c/0x2a0 lib/nmi_backtrace.c:65
 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>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 29688 Comm: kworker/u8:0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
RIP: 0010:unwind_next_frame+0x44/0x2090 arch/x86/kernel/unwind_orc.c:709
Code: 55 49 89 fd 41 54 55 53 48 83 ec 38 0f b6 04 02 84 c0 74 08 3c 03 0f 8e 42 0b 00 00 41 8b 5d 00 31 ed 85 db 75 15 48 83 c4 38 <89> e8 5b 5d 41 5c 41 5d 41 5e 41 5f e9 8b ef 05 0a 48 b8 00 00 00
RSP: 0018:ffffc90003f078e0 EFLAGS: 00000092
RAX: 0000000000000000 RBX: ffffc90003f07b98 RCX: ffffc90003f0786c
RDX: 0000000000000000 RSI: ffffffff8e17fc5f RDI: ffff88804d4e4f44
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000000 R11: 0000000000088735 R12: ffffc90003f07968
R13: ffffc90003f07918 R14: ffffc90003f07b98 R15: ffffc90003f0794c
FS:  0000000000000000(0000) GS:ffff888123edc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c6b5eb158 CR3: 0000000072da6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 metadata_update_state+0x2eb/0x360 mm/kfence/core.c:318
 kfence_guarded_free+0x11b/0x5d0 mm/kfence/core.c:562
 __kfence_free+0xb1/0x1d0 mm/kfence/core.c:1270
 kfence_free include/linux/kfence.h:187 [inline]
 slab_free_hook mm/slub.c:2615 [inline]
 slab_free mm/slub.c:6377 [inline]
 kmem_cache_free+0x5ee/0x6b0 mm/slub.c:6504
 kfree_skbmem+0x19a/0x210 net/core/skbuff.c:1139
 __kfree_skb net/core/skbuff.c:1206 [inline]
 consume_skb net/core/skbuff.c:1439 [inline]
 consume_skb+0xd1/0x110 net/core/skbuff.c:1433
 batadv_forw_packet_free+0x1c8/0x250 net/batman-adv/send.c:458
 batadv_iv_send_outstanding_bat_ogm_packet+0x275/0x800 net/batman-adv/bat_iv_ogm.c:1813
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
 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>