INFO: task syz.3.2819:15241 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.3.2819 state:D stack:28160 pid:15241 tgid:15240 ppid:13673 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x1709/0x5530 kernel/sched/core.c:7231
__schedule_loop kernel/sched/core.c:7308 [inline]
rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7604
rt_mutex_slowlock_block+0x55c/0x680 kernel/locking/rtmutex.c:1670
__rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1787 [inline]
rt_mutex_slowlock+0x2d4/0x780 kernel/locking/rtmutex.c:1827
__rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
write_ports+0xb5/0xd20 fs/nfsd/nfsctl.c:865
nfsctl_transaction_write+0x112/0x160 fs/nfsd/nfsctl.c:112
vfs_write+0x29f/0xbb0 fs/read_write.c:685
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1b7cdde0d9
RSP: 002b:00007f1b7b036028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1b7d065fa0 RCX: 00007f1b7cdde0d9
RDX: 0000000000000ff7 RSI: 0000200000000180 RDI: 0000000000000003
RBP: 00007f1b7ce75024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1b7d066038 R14: 00007f1b7d065fa0 R15: 00007ffca31e4c58
Showing all locks held in the system:
locks held by khungtaskd/39: 1, last CPU#1:
#0: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffffffff8e3c3880 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6835
locks held by getty/5351: 2, on CPU#0:
#0: ffff88803702d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900044c32e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x460/0x1360 drivers/tty/n_tty.c:2211
locks held by kworker/0:4/5690: 2, on CPU#0:
#0: ffff88813fe63938 ((wq_completion)events){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffff88813fe63938 ((wq_completion)events){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffff88813fe63938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7fd/0x1480 kernel/workqueue.c:3344
#1: ffffc900053ffc60 ((work_completion)(&blkg->free_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#1: ffffc900053ffc60 ((work_completion)(&blkg->free_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#1: ffffc900053ffc60 ((work_completion)(&blkg->free_work)){+.+.}-{0:0}, at: process_one_work+0x7fd/0x1480 kernel/workqueue.c:3344
locks held by kworker/u8:1/11982: 3, on CPU#1:
#0: ffff88801aea4138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffff88801aea4138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffff88801aea4138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7fd/0x1480 kernel/workqueue.c:3344
#1: ffffc9000748fc60 ((linkwatch_work).work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#1: ffffc9000748fc60 ((linkwatch_work).work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#1: ffffc9000748fc60 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7fd/0x1480 kernel/workqueue.c:3344
#2: ffffffff8f7c4a78 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313
locks held by syz.4.2505/14127: 3, on CPU#1:
#0: ffff88803412d128 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
#1: ffff888034c30510 (sb_writers#29){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2731 [inline]
#1: ffff888034c30510 (sb_writers#29){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
#2: ffffffff8e6eeb78 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd20 fs/nfsd/nfsctl.c:865
locks held by syz.3.2819/15241: 3, on CPU#1:
#0: ffff88803806ad28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
#1: ffff88803d0ec510 (sb_writers#29){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2731 [inline]
#1: ffff88803d0ec510 (sb_writers#29){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
#2: ffffffff8e6eeb78 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd20 fs/nfsd/nfsctl.c:865
locks held by syz.5.2894/15486: 3, on CPU#1:
#0: ffff8880375fff28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
#1: ffff88803558c510 (sb_writers#29){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2731 [inline]
#1: ffff88803558c510 (sb_writers#29){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
#2: ffffffff8e6eeb78 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd20 fs/nfsd/nfsctl.c:865
locks held by syz.8.3520/17646: 1, last CPU#1:
#0: ffff88805bcb40e8 (&kvm->slots_lock){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
#0: ffff88805bcb40e8 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_memory_region+0x67/0xa0 virt/kvm/kvm_main.c:2146
locks held by syz.6.3524/17659: 1, on CPU#0:
#0: ffffffff8f7c4a78 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline]
#0: ffffffff8f7c4a78 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3510
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 39 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT_{RT,(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: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 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64
Code: 0c 74 02 c3 cc cc cc cc 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 13 66 19 00 fb f4 4c d0 03 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffffff8e007ca0 EFLAGS: 00000242
RAX: 000000000085be0b RBX: ffffffff8199b400 RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8d98ba58 RDI: ffffffff8bcbd080
RBP: ffffffff8e007d78 R08: ffff8880b8633d1b R09: 1ffff110170c67a3
R10: dffffc0000000000 R11: ffffed10170c67a4 R12: 0000000000000000
R13: 1ffffffff1c1edf0 R14: 1ffffffff1c00f9c R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8881259f2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2dc04ff8 CR3: 0000000073872000 CR4: 00000000003526f0
DR0: 0000000000000008 DR1: 0000000000000002 DR2: 0000000000000404
DR3: ffffffffefffff14 DR6: 00000000ffff0ff0 DR7: 0000000000000400
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
cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:454
rest_init+0x378/0x3a0 init/main.c:727
start_kernel+0x392/0x3e0 init/main.c:1185
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