INFO: task syz.5.2769:16300 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.5.2769 state:D stack:26248 pid:16300 tgid:16299 ppid:14177 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 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+0x7bf/0x1550 kernel/locking/mutex.c:821 nfsd_nl_cache_flush_doit+0xe2/0x1b0 fs/nfsd/nfsctl.c:2236 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline] genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 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+0x7bb/0x940 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775 __sock_sendmsg net/socket.c:790 [inline] ____sys_sendmsg+0x54e/0x850 net/socket.c:2684 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738 __sys_sendmsg net/socket.c:2770 [inline] __do_sys_sendmsg net/socket.c:2775 [inline] __se_sys_sendmsg net/socket.c:2773 [inline] __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fbcdc59de99 RSP: 002b:00007fbcdd531028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fbcdc825fa0 RCX: 00007fbcdc59de99 RDX: 0000000004000880 RSI: 0000200000000100 RDI: 0000000000000003 RBP: 00007fbcdc633eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fbcdc826038 R14: 00007fbcdc825fa0 R15: 00007ffe3b465b28 Showing all locks held in the system: 1 lock held by khungtaskd/30: #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 1 lock held by klogd/4982: #0: ffff8880b873b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160 kernel/sched/core.c:667 2 locks held by getty/5383: #0: ffff888035c370a0 (&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+0x45a/0x1360 drivers/tty/n_tty.c:2211 3 locks held by kworker/0:7/5764: #0: ffff88801b029d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline] #0: ffff88801b029d40 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405 #1: ffffc900054afc40 ((crda_timeout).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline] #1: ffffc900054afc40 ((crda_timeout).work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405 #2: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: crda_timeout_work+0x16/0x80 net/wireless/reg.c:529 3 locks held by kworker/u8:15/11389: #0: ffff88801b06c140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline] #0: ffff88801b06c140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405 #1: ffffc900033afc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline] #1: ffffc900033afc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405 #2: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313 3 locks held by kworker/u8:18/12182: #0: ffff88801b129140 ((wq_completion)tc_filter_workqueue){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline] #0: ffff88801b129140 ((wq_completion)tc_filter_workqueue){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405 #1: ffffc9001b9ffc40 ((work_completion)(&(rwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline] #1: ffffc9001b9ffc40 ((work_completion)(&(rwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405 #2: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: mall_destroy_work+0x16/0x30 net/sched/cls_matchall.c:63 2 locks held by syz.3.2073/13587: #0: ffffffff9009d608 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8ee8e5e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x135/0x1750 fs/nfsd/nfsctl.c:1964 2 locks held by syz.5.2769/16300: #0: ffffffff9009d608 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8ee8e5e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_cache_flush_doit+0xe2/0x1b0 fs/nfsd/nfsctl.c:2236 2 locks held by syz.2.2933/16950: #0: ffffffff9009d608 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8ee8e5e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_cache_flush_doit+0xb5/0x1b0 fs/nfsd/nfsctl.c:2236 2 locks held by syz.6.4009/21247: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline] #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3506 #1: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline] #1: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770 kernel/rcu/tree_exp.h:961 1 lock held by syz.0.4013/21260: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline] #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3506 1 lock held by syz.0.4013/21262: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: tc_new_tfilter+0x502/0x1850 net/sched/cls_api.c:2313 1 lock held by syz.7.4016/21267: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3bc/0x1e10 drivers/net/tun.c:3148 1 lock held by syz.7.4016/21270: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: tun_set_queue drivers/net/tun.c:3021 [inline] #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x36c/0x1e10 drivers/net/tun.c:3141 1 lock held by syz.4.4017/21269: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3bc/0x1e10 drivers/net/tun.c:3148 1 lock held by syz.4.4017/21276: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7082 1 lock held by syz.4.4017/21280: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7082 2 locks held by syz.1.4021/21295: #0: ffffffff905960c8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #0: ffffffff905960c8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #0: ffffffff905960c8 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570 #1: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #1: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline] #1: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a3/0x1bd0 net/core/rtnetlink.c:4158 1 lock held by syz.1.4021/21296: #0: ffffffff9002cd80 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x3bc/0x1e10 drivers/net/tun.c:3148 ============================================= 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 06/25/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122 nmi_trigger_cpumask_backtrace+0x17a/0x380 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+0x135/0x170 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline] watchdog+0xfd7/0x1030 kernel/hung_task.c:561 kthread+0x388/0x470 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 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64 Code: dc 7f 02 e9 13 05 03 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 aa 19 00 fb f4 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 RSP: 0018:ffffffff8e807de0 EFLAGS: 00000242 RAX: 000000000020340d RBX: ffffffff819ab450 RCX: 0000000080000001 RDX: 0000000000000001 RSI: ffffffff8e22ba9f RDI: ffffffff8c4bda80 RBP: ffffffff8e807eb8 R08: ffff8880b86338db R09: 1ffff110170c671b R10: dffffc0000000000 R11: ffffed10170c671c R12: 0000000000000000 R13: 1ffffffff1d11de8 R14: 1ffffffff1d00fc4 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888124f54000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000000754d4000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/kernel/process.c:767 [inline] default_idle+0x9/0x20 arch/x86/kernel/process.c:768 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x2e0/0x540 kernel/sched/idle.c:355 IPVS: rr: UDP 255.255.255.255:0 - no destination available cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:454 rest_init+0x2de/0x300 init/main.c:717 start_kernel+0x392/0x3e0 init/main.c:1175 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x137/0x1b0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x157