INFO: task syz-executor:7908 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-executor state:D stack:23784 pid:7908 tgid:7908 ppid:1 task_flags:0x400140 flags:0x00080002 Call Trace: 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_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 nfsd_umount+0x3b/0x60 fs/nfsd/nfsctl.c:1364 deactivate_locked_super+0xc1/0x1b0 fs/super.c:476 deactivate_super fs/super.c:509 [inline] deactivate_super+0xe7/0x110 fs/super.c:505 cleanup_mnt+0x21f/0x450 fs/namespace.c:1312 task_work_run+0x150/0x240 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0x107/0x4f0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x6f2/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc84299e097 RSP: 002b:00007ffd80931008 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007fc842a321ca RCX: 00007fc84299e097 RDX: 0000000000000004 RSI: 0000000000000009 RDI: 00007ffd80932150 RBP: 00007ffd8093213c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd80932150 R13: 00007fc842a321ca R14: 0000000000098c21 R15: 00007ffd80932190 Showing all locks held in the system: 2 locks held by kworker/u8:1/13: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90000127d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 1 lock held by khungtaskd/30: #0: ffffffff8e7e52e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #0: ffffffff8e7e52e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #0: ffffffff8e7e52e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775 2 locks held by kworker/u8:3/48: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90000b97d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 1 lock held by sshd-session/5612: #0: ffff8880b843b3e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x140 kernel/sched/core.c:652 2 locks held by getty/6250: #0: ffff8880380810a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc9000bcc32e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14f0 drivers/tty/n_tty.c:2211 2 locks held by kworker/u8:9/7313: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90003ee7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:10/7323: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90003ef7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:11/7327: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90003f07d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:12/7337: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90003f17d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:13/7339: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90003f27d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:14/7452: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90004fe7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:15/7454: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90002f07d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by syz-executor/7908: #0: ffff8880887e80d8 (&type->s_umount_key#58){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline] #0: ffff8880887e80d8 (&type->s_umount_key#58){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline] #0: ffff8880887e80d8 (&type->s_umount_key#58){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline] #0: ffff8880887e80d8 (&type->s_umount_key#58){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505 #1: ffffffff8ec61b20 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 2 locks held by kworker/u8:16/8350: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc900035f7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:17/8351: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc900038d7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:18/8352: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc900038c7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:19/8353: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90003607d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:20/8354: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc900036d7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:21/8355: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc900035e7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:22/8356: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc900035d7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:23/8357: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc900035c7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:24/8358: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc900035b7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:25/12903: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90005d4fd08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:26/12904: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90005b0fd08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 4 locks held by kworker/u8:27/12905: #0: ffff88801c6ae140 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90005adfd08 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 #2: ffffffff905f6368 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xb8/0x920 net/core/net_namespace.c:673 #3: ffffffff8e7f0e28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311 2 locks held by kworker/u8:28/12907: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90005abfd08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:29/12908: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90005a9fd08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by syz.0.1730/13712: #0: ffffffff906bd588 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8ec61b20 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x8ec/0x12b0 fs/nfsd/nfsctl.c:1633 4 locks held by kworker/0:3/14202: #0: ffff8880b843b3e0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x140 kernel/sched/core.c:652 #1: ffff88807682e008 (&____s->seqcount#15){.-.-}-{0:0}, at: trace_find_filtered_pid kernel/trace/trace_pid.c:15 [inline] #1: ffff88807682e008 (&____s->seqcount#15){.-.-}-{0:0}, at: trace_ignore_this_task+0xbc/0x100 kernel/trace/trace_pid.c:44 #2: ffff88802778a958 (&helper->damage_lock){....}-{3:3}, at: drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:243 [inline] #2: ffff88802778a958 (&helper->damage_lock){....}-{3:3}, at: drm_fb_helper_damage_work+0x1ce/0x640 drivers/gpu/drm/drm_fb_helper.c:275 #3: ffffffff9b404af8 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x144/0x490 lib/debugobjects.c:835 2 locks held by syz-executor/14980: #0: ffff88808e41a0d8 (&type->s_umount_key#58){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline] #0: ffff88808e41a0d8 (&type->s_umount_key#58){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline] #0: ffff88808e41a0d8 (&type->s_umount_key#58){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline] #0: ffff88808e41a0d8 (&type->s_umount_key#58){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505 #1: ffffffff8ec61b20 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 2 locks held by syz.8.2106/16275: #0: ffffffff906bd588 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8ec61b20 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1c1/0x820 fs/nfsd/nfsctl.c:1728 1 lock held by syz-executor/16505: #0: ffffffff8e7f0e28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343 2 locks held by syz.6.2304/17097: 1 lock held by syz.5.2322/17158: #0: ffffffff8e7f0cf8 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x6d0 kernel/rcu/tree.c:3828 2 locks held by kworker/u8:30/17174: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90003f87d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:31/17175: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90005147d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:32/17176: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90004e27d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:33/17177: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90004e17d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:34/17178: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90004e07d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:35/17179: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90004df7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:36/17180: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90004de7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 2 locks held by kworker/u8:37/17181: #0: ffff88801bb72140 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277 #1: ffffc90004dd7d08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278 ============================================= 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 04/18/2026 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: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