INFO: task syz.2.1023:7130 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1023 state:D stack:26752 pid:7130 ppid:4276 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5257 [inline]
__schedule+0x1089/0x4140 kernel/sched/core.c:6584
schedule+0xb9/0x180 kernel/sched/core.c:6660
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6719
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x562/0xb40 kernel/locking/mutex.c:747
write_ports+0xb3/0xb80 fs/nfsd/nfsctl.c:846
nfsctl_transaction_write fs/nfsd/nfsctl.c:114 [inline]
nfsctl_transaction_read+0x165/0x1b0 fs/nfsd/nfsctl.c:129
do_loop_readv_writev include/linux/uio.h:-1 [inline]
do_iter_read+0x482/0xb10 fs/read_write.c:798
vfs_readv fs/read_write.c:916 [inline]
do_readv+0x260/0x460 fs/read_write.c:953
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4ea2b9f559
RSP: 002b:00007f4ea3a73028 EFLAGS: 00000246 ORIG_RAX: 0000000000000013
RAX: ffffffffffffffda RBX: 00007f4ea2e25fa0 RCX: 00007f4ea2b9f559
RDX: 0000000000000002 RSI: 00002000000022c0 RDI: 0000000000000003
RBP: 00007f4ea2c36b50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4ea2e26038 R14: 00007f4ea2e25fa0 R15: 00007ffcfca24f88
Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8db2e3f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xce0 kernel/rcu/tasks.h:543
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8db2ec30 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xce0 kernel/rcu/tasks.h:543
1 lock held by khungtaskd/28:
#0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8db2daa0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6669
2 locks held by getty/4028:
#0: ffff88814cb60098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x430/0x1400 drivers/tty/n_tty.c:2198
2 locks held by kworker/0:6/4356:
#0: ffff888018472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
#1: ffffc900048efd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
3 locks held by syz.3.1012/7095:
#0: ffff888023c31268 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
#1: ffff88802b30c460 (sb_writers#32){.+.+}-{0:0}, at: vfs_write+0x270/0x9a0 fs/read_write.c:580
#2: ffffffff8ddcd208 (nfsd_mutex){+.+.}-{3:3}, at: write_ports+0xb3/0xb80 fs/nfsd/nfsctl.c:846
2 locks held by syz.2.1023/7130:
#0: ffff8880306a3768 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
#1: ffffffff8ddcd208 (nfsd_mutex){+.+.}-{3:3}, at: write_ports+0xb3/0xb80 fs/nfsd/nfsctl.c:846
3 locks held by syz.1.1111/7373:
#0: ffff8880770bad68 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
#1: ffff8880240c0460 (sb_writers#32){.+.+}-{0:0}, at: vfs_write+0x270/0x9a0 fs/read_write.c:580
#2: ffffffff8ddcd208 (nfsd_mutex){+.+.}-{3:3}, at: nfsd4_write_time+0xa4/0x330 fs/nfsd/nfsctl.c:980
1 lock held by syz.4.1171/7514:
#0: ffffffff8ddcd208 (nfsd_mutex){+.+.}-{3:3}, at: write_versions+0x90/0xbb0 fs/nfsd/nfsctl.c:681
2 locks held by syz.6.1320/7915:
#0: ffff88807bd8efe8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
#1: ffffffff8ddcd208 (nfsd_mutex){+.+.}-{3:3}, at: write_pool_threads+0x10b/0x5e0 fs/nfsd/nfsctl.c:468
3 locks held by syz.0.1350/8005:
#0: ffff88807d55b4e8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
#1: ffff88804390c460 (sb_writers#32){.+.+}-{0:0}, at: vfs_write+0x270/0x9a0 fs/read_write.c:580
#2: ffffffff8ddcd208 (nfsd_mutex){+.+.}-{3:3}, at: nfsd4_write_time+0xa4/0x330 fs/nfsd/nfsctl.c:980
3 locks held by syz.7.1500/8414:
#0: ffff8880314919e8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
#1: ffff888076234460 (sb_writers#32){.+.+}-{0:0}, at: vfs_writev fs/read_write.c:933 [inline]
#1: ffff888076234460 (sb_writers#32){.+.+}-{0:0}, at: do_writev+0x25d/0x480 fs/read_write.c:977
#2: ffffffff8ddcd208 (nfsd_mutex){+.+.}-{3:3}, at: nfsd4_write_time+0xa4/0x330 fs/nfsd/nfsctl.c:980
3 locks held by syz.3.1716/9020:
#0: ffff88801feebc68 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ae/0x360 fs/file.c:1038
#1: ffff88807a286460 (sb_writers#32){.+.+}-{0:0}, at: vfs_write+0x270/0x9a0 fs/read_write.c:580
#2: ffffffff8ddcd208 (nfsd_mutex){+.+.}-{3:3}, at: write_maxblksize+0x2c2/0x380 fs/nfsd/nfsctl.c:892
1 lock held by syz-executor/9319:
#0: ffffffff8db337b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
#0: ffffffff8db337b8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2ec/0x890 kernel/rcu/tree_exp.h:962
=============================================
NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
watchdog+0xf0e/0xf50 kernel/hung_task.c:377
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295