INFO: task syz-executor:5603 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:22376 pid:5603 tgid:5603 ppid:1 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5535 [inline]
__schedule+0x1b47/0x5c60 kernel/sched/core.c:7305
__schedule_loop kernel/sched/core.c:7382 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7397
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7454
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c4/0x15a0 kernel/locking/mutex.c:821
nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:590
nfsd_umount+0x41/0x60 fs/nfsd/nfsctl.c:1379
deactivate_locked_super+0xbe/0x110 fs/super.c:586
cleanup_mnt+0x3d3/0x460 fs/namespace.c:1317
task_work_run+0x1d9/0x260 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:70 [inline]
exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101
__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:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline]
do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9a4bf9f397
RSP: 002b:00007ffcad522248 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f9a4c0344bb RCX: 00007f9a4bf9f397
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffcad522300
RBP: 00007ffcad522300 R08: 00007ffcad523300 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcad523390
R13: 00007f9a4c0344bb R14: 000000000004781e R15: 00007ffcad5233d0
INFO: task syz.6.1175:9699 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.6.1175 state:D stack:27424 pid:9699 tgid:9697 ppid:8959 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5535 [inline]
__schedule+0x1b47/0x5c60 kernel/sched/core.c:7305
__schedule_loop kernel/sched/core.c:7382 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7397
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7454
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c4/0x15a0 kernel/locking/mutex.c:821
write_ports+0xb5/0xd10 fs/nfsd/nfsctl.c:874
nfsctl_transaction_write+0x10f/0x160 fs/nfsd/nfsctl.c:117
vfs_write+0x296/0xba0 fs/read_write.c:685
ksys_write+0x150/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f30aff9e159
RSP: 002b:00007f30b0dad028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f30b0225fa0 RCX: 00007f30aff9e159
RDX: 0000000000000013 RSI: 0000200000000240 RDI: 0000000000000005
RBP: 00007f30b003506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f30b0226038 R14: 00007f30b0225fa0 R15: 00007fffd83660c8
Showing all locks held in the system:
locks held by khungtaskd/34: 1, last CPU#0:
#0: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8f15c2a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by getty/5362: 2, on CPU#0:
#0: ffff88801c7b60a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by syz-executor/5603: 2, on CPU#0:
#0: ffff88807ef600e8 (&type->s_umount_key#77){+.+.}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88807ef600e8 (&type->s_umount_key#77){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
#0: ffff88807ef600e8 (&type->s_umount_key#77){+.+.}-{4:4}, at: deactivate_super+0xac/0xe0 fs/super.c:613
#1: ffffffff8f49f8e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:590
locks held by syz.4.1137/9549: 3, on CPU#0:
#0: ffff888079138ef0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1408
#1: ffff8880330f8460 (sb_writers#29){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#1: ffff8880330f8460 (sb_writers#29){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffffffff8f49f8e0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10 fs/nfsd/nfsctl.c:874
locks held by syz.6.1175/9699: 3, on CPU#0:
#0: ffff88807e8db430 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1408
#1: ffff88802bfe4460 (sb_writers#29){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#1: ffff88802bfe4460 (sb_writers#29){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffffffff8f49f8e0 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10 fs/nfsd/nfsctl.c:874
locks held by syz.7.1517/10873: 2, on CPU#0:
#0: ffff88803c5c80e8 (&type->s_umount_key#77){+.+.}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88803c5c80e8 (&type->s_umount_key#77){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
#0: ffff88803c5c80e8 (&type->s_umount_key#77){+.+.}-{4:4}, at: deactivate_super+0xac/0xe0 fs/super.c:613
#1: ffffffff8f49f8e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:590
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 34 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123
nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66
trigger_all_cpu_backtrace include/linux/nmi.h:164 [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:377 [inline]
watchdog+0x1058/0x10d0 kernel/hung_task.c:598
kthread+0x38b/0x480 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