INFO: task syz.6.1064:11560 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.6.1064 state:D stack:26896 pid:11560 tgid:11558 ppid:6268 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5295 [inline] __schedule+0xfee/0x6120 kernel/sched/core.c:6908 __schedule_loop kernel/sched/core.c:6990 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7005 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062 __mutex_lock_common kernel/locking/mutex.c:692 [inline] __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776 expkey_flush+0x18/0x90 fs/nfsd/export.c:250 write_flush.isra.0+0x2af/0x3d0 net/sunrpc/cache.c:1551 pde_write fs/proc/inode.c:330 [inline] proc_reg_write+0x240/0x330 fs/proc/inode.c:342 do_loop_readv_writev fs/read_write.c:852 [inline] do_loop_readv_writev fs/read_write.c:837 [inline] vfs_writev+0x5ea/0xe10 fs/read_write.c:1061 do_writev+0x13e/0x340 fs/read_write.c:1105 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2318f9c799 RSP: 002b:00007f2319ed0028 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f2319215fa0 RCX: 00007f2318f9c799 RDX: 000000000000000a RSI: 0000200000000240 RDI: 000000000000000a RBP: 00007f2319032c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2319216038 R14: 00007f2319215fa0 R15: 00007ffeb3548758 Showing all locks held in the system: 1 lock held by khungtaskd/30: #0: ffffffff8e7e7460 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline] #0: ffffffff8e7e7460 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline] #0: ffffffff8e7e7460 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775 4 locks held by kworker/u8:2/35: #0: ffff88801c6ae948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x1287/0x1920 kernel/workqueue.c:3250 #1: ffffc90000ab7d08 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x93c/0x1920 kernel/workqueue.c:3251 #2: ffffffff905fac50 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xb8/0x920 net/core/net_namespace.c:675 #3: ffffffff8e7f3078 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343 2 locks held by getty/5584: #0: ffff888036ca30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211 2 locks held by kworker/1:3/5830: #0: ffff88813fe63148 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1287/0x1920 kernel/workqueue.c:3250 #1: ffffc90004107d08 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x93c/0x1920 kernel/workqueue.c:3251 2 locks held by syz.7.85/6582: 2 locks held by syz.4.98/6696: 1 lock held by dhcpcd/7060: #0: ffff888062aa35c8 (&sb->s_type->i_mutex_key#14){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline] #0: ffff888062aa35c8 (&sb->s_type->i_mutex_key#14){+.+.}-{4:4}, at: __sock_release+0x86/0x260 net/socket.c:661 2 locks held by syz.4.301/7913: 3 locks held by syz.7.404/8429: 2 locks held by syz.7.425/8520: 2 locks held by syz.7.465/8782: #0: ffff888035255900 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:536 [inline] #0: ffff888035255900 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x22c/0xa30 mm/mmap.c:1310 #1: ffff88802d14fa08 (&anon_vma->rwsem){++++}-{4:4}, at: anon_vma_lock_write mm/internal.h:220 [inline] #1: ffff88802d14fa08 (&anon_vma->rwsem){++++}-{4:4}, at: unlink_anon_vmas+0xe1/0x8e0 mm/rmap.c:486 2 locks held by syz.4.584/9316: 2 locks held by syz.4.603/9399: 2 locks held by syz.7.649/9608: #0: ffff88807ba70f80 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock include/linux/mmap_lock.h:536 [inline] #0: ffff88807ba70f80 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x22c/0xa30 mm/mmap.c:1310 #1: ffff88802d14fa08 (&anon_vma->rwsem){++++}-{4:4}, at: anon_vma_lock_write mm/internal.h:220 [inline] #1: ffff88802d14fa08 (&anon_vma->rwsem){++++}-{4:4}, at: unlink_anon_vmas+0xe1/0x8e0 mm/rmap.c:486 2 locks held by syz.4.741/10065: 2 locks held by syz.4.827/10430: 2 locks held by syz.4.839/10453: 1 lock held by syz.4.971/11065: 1 lock held by syz.4.1003/11200: 2 locks held by syz.5.999/11230: #0: ffffffff906bf810 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8ec579c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x6c1/0xc00 fs/nfsd/nfsctl.c:1597 1 lock held by syz.4.1032/11382: 3 locks held by syz.6.1064/11560: #0: ffff888036e55978 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1261 #1: ffff88805c8a8420 (sb_writers#3){.+.+}-{0:0}, at: do_writev+0x13e/0x340 fs/read_write.c:1105 #2: ffffffff8ec579c8 (nfsd_mutex){+.+.}-{4:4}, at: expkey_flush+0x18/0x90 fs/nfsd/export.c:250 2 locks held by syz-executor/11787: #0: ffff888062e000e0 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline] #0: ffff888062e000e0 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline] #0: ffff888062e000e0 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline] #0: ffff888062e000e0 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505 #1: ffffffff8ec579c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 2 locks held by syz.4.1157/12021: 2 locks held by syz.4.1165/12062: 2 locks held by syz.4.1169/12072: 1 lock held by syz.4.1182/12170: 2 locks held by syz-executor/12574: #0: ffff88803418e0e0 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline] #0: ffff88803418e0e0 (&type->s_umount_key#57){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline] #0: ffff88803418e0e0 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline] #0: ffff88803418e0e0 (&type->s_umount_key#57){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505 #1: ffffffff8ec579c8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 1 lock held by syz.8.1428/13477: #0: ffffffff8e7f3078 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343 1 lock held by syz-executor/13755: #0: ffffffff906134a8 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline] #0: ffffffff906134a8 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3436 1 lock held by syz.7.1512/13960: 2 locks held by syz.4.1517/13991: 1 lock held by syz.4.1532/14107: 1 lock held by dhcpcd/14122: #0: ffff88807ca0a260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline] #0: ffff88807ca0a260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf50 net/packet/af_packet.c:3197 1 lock held by dhcpcd/14123: #0: ffff8880619d0260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline] #0: ffff8880619d0260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf50 net/packet/af_packet.c:3197 1 lock held by dhcpcd/14124: #0: ffff8880318c8260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline] #0: ffff8880318c8260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf50 net/packet/af_packet.c:3197 1 lock held by dhcpcd/14125: #0: ffff8880619d2260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline] #0: ffff8880619d2260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf50 net/packet/af_packet.c:3197 1 lock held by dhcpcd/14126: #0: ffff888035994260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline] #0: ffff888035994260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf50 net/packet/af_packet.c:3197 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026 Call Trace: __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:161 [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:346 [inline] watchdog+0xd25/0x1050 kernel/hung_task.c:515 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 12695 Comm: kworker/0:0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026 Workqueue: events_long defense_work_handler RIP: 0010:hlock_class kernel/locking/lockdep.c:234 [inline] RIP: 0010:mark_lock+0x52/0xa20 kernel/locking/lockdep.c:4731 Code: 89 d3 83 fa 08 74 6d 41 be 01 00 00 00 89 d9 41 d3 e6 4d 63 f6 41 0f b7 44 24 20 66 25 ff 1f 0f b7 c0 48 0f a3 05 3e dd 2f 14 <73> 5b 48 8d 04 80 48 8d 04 80 48 8d 04 c5 a0 0b 14 96 4c 89 f1 48 RSP: 0018:ffffc90000007c50 EFLAGS: 00000003 RAX: 0000000000000457 RBX: 0000000000000002 RCX: 0000000000000002 RDX: 0000000000000002 RSI: ffff88802f93c858 RDI: ffff88802f93bd00 RBP: ffffc90000007ce8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88802f93c858 R13: ffff88802f93bd00 R14: 0000000000000004 R15: 1ffff92000000fac FS: 0000000000000000(0000) GS:ffff88812434d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005606b46d44b0 CR3: 0000000031370000 CR4: 00000000003526f0 Call Trace: mark_held_locks+0x40/0x70 kernel/locking/lockdep.c:4325 __trace_hardirqs_on_caller kernel/locking/lockdep.c:4343 [inline] lockdep_hardirqs_on_prepare kernel/locking/lockdep.c:4410 [inline] lockdep_hardirqs_on_prepare+0xb4/0x1b0 kernel/locking/lockdep.c:4362 trace_hardirqs_on+0x36/0x40 kernel/trace/trace_preemptirq.c:78 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:178 [inline] _raw_spin_unlock_irqrestore+0x52/0x80 kernel/locking/spinlock.c:194 debug_object_deactivate+0x2e4/0x3b0 lib/debugobjects.c:905 debug_rcu_head_unqueue kernel/rcu/rcu.h:248 [inline] rcu_do_batch kernel/rcu/tree.c:2609 [inline] rcu_core+0x532/0x10d0 kernel/rcu/tree.c:2869 handle_softirqs+0x1eb/0x9e0 kernel/softirq.c:622 do_softirq kernel/softirq.c:523 [inline] do_softirq+0xac/0xe0 kernel/softirq.c:510 __local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450 local_bh_enable include/linux/bottom_half.h:33 [inline] update_defense_level+0x607/0xf50 net/netfilter/ipvs/ip_vs_ctl.c:209 defense_work_handler+0x26/0xd0 net/netfilter/ipvs/ip_vs_ctl.c:234 process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275 process_scheduled_works kernel/workqueue.c:3358 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3439 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245