INFO: task syz-executor:20649 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:23992 pid:20649 tgid:20649 ppid:1 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0xfe6/0x5fa0 kernel/sched/core.c:6867 __schedule_loop kernel/sched/core.c:6949 [inline] schedule+0xdd/0x390 kernel/sched/core.c:6964 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021 __mutex_lock_common kernel/locking/mutex.c:692 [inline] __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776 nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575 nfsd_umount+0x3b/0x60 fs/nfsd/nfsctl.c:1353 deactivate_locked_super+0xc1/0x1b0 fs/super.c:474 deactivate_super fs/super.c:507 [inline] deactivate_super+0xe7/0x110 fs/super.c:503 cleanup_mnt+0x21f/0x450 fs/namespace.c:1318 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:44 [inline] exit_to_user_mode_loop+0x100/0x4b0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x4ea/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9b9059c1d7 RSP: 002b:00007ffdca0e96d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007f9b90630b3b RCX: 00007f9b9059c1d7 RDX: 0000000000000004 RSI: 0000000000000009 RDI: 00007ffdca0ea820 RBP: 00007ffdca0ea80c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffdca0ea820 R13: 00007f9b90630b3b R14: 00000000000d6160 R15: 00007ffdca0ea860 INFO: task syz-executor:22414 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-executor state:D stack:24328 pid:22414 tgid:22414 ppid:1 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0xfe6/0x5fa0 kernel/sched/core.c:6867 __schedule_loop kernel/sched/core.c:6949 [inline] schedule+0xdd/0x390 kernel/sched/core.c:6964 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021 __mutex_lock_common kernel/locking/mutex.c:692 [inline] __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776 nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575 nfsd_umount+0x3b/0x60 fs/nfsd/nfsctl.c:1353 deactivate_locked_super+0xc1/0x1b0 fs/super.c:474 deactivate_super fs/super.c:507 [inline] deactivate_super+0xe7/0x110 fs/super.c:503 cleanup_mnt+0x21f/0x450 fs/namespace.c:1318 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:44 [inline] exit_to_user_mode_loop+0x100/0x4b0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x4ea/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa9e859c1d7 RSP: 002b:00007fff4854e568 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007fa9e8630b3b RCX: 00007fa9e859c1d7 RDX: 0000000000000004 RSI: 0000000000000009 RDI: 00007fff4854f6b0 RBP: 00007fff4854f69c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff4854f6b0 R13: 00007fa9e8630b3b R14: 00000000000e0402 R15: 00007fff4854f6f0 Showing all locks held in the system: 1 lock held by pool_workqueue_/3: #0: ffffffff8e5ef8f8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343 1 lock held by khungtaskd/31: #0: ffffffff8e5e3120 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e5e3120 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8e5e3120 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775 4 locks held by kworker/u8:28/9137: #0: ffff88801c29f148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232 #1: ffffc9000380fc98 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233 #2: ffffffff903dd430 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xab/0x830 net/core/net_namespace.c:670 #3: ffffffff903f5d68 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0x90/0xc60 net/core/dev.c:13037 1 lock held by syz.1.2965/20387: 2 locks held by syz.3.3019/20645: #0: ffff888035a3e0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline] #0: ffff888035a3e0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline] #0: ffff888035a3e0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline] #0: ffff888035a3e0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575 2 locks held by syz-executor/20649: #0: ffff88803fbf20e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline] #0: ffff88803fbf20e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline] #0: ffff88803fbf20e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline] #0: ffff88803fbf20e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575 2 locks held by syz.0.3320/22166: #0: ffffffff904a2bd0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x687/0xbc0 fs/nfsd/nfsctl.c:1596 2 locks held by syz-executor/22414: #0: ffff88802897e0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline] #0: ffff88802897e0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline] #0: ffff88802897e0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline] #0: ffff88802897e0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575 2 locks held by syz-executor/23457: #0: ffff8880319b00e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline] #0: ffff8880319b00e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline] #0: ffff8880319b00e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline] #0: ffff8880319b00e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575 2 locks held by getty/23771: #0: ffff888030eda0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc90003caf2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211 2 locks held by syz.5.3690/23957: #0: ffffffff904a2bd0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1b20 fs/nfsd/nfsctl.c:1886 2 locks held by syz-executor/24286: #0: ffff88802ea280e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline] #0: ffff88802ea280e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline] #0: ffff88802ea280e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline] #0: ffff88802ea280e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575 2 locks held by syz.7.3798/24591: #0: ffff8880792da0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline] #0: ffff8880792da0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline] #0: ffff8880792da0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline] #0: ffff8880792da0e0 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575 2 locks held by syz.9.3890/25221: #0: ffffffff904a2bd0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218 #1: ffffffff8ea476a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1b20 fs/nfsd/nfsctl.c:1886 ============================================= 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 01/24/2026 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+0xcc3/0xfe0 kernel/hung_task.c:515 kthread+0x3b3/0x730 kernel/kthread.c:463 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246