INFO: task syz.2.1202:9595 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.2.1202 state:D stack:27944 pid:9595 tgid:9589 ppid:5604 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5526 [inline]
__schedule+0x1259/0x6920 kernel/sched/core.c:7277
__schedule_loop kernel/sched/core.c:7354 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7369
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7426
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0xccb/0x1bd0 kernel/locking/mutex.c:821
write_threads+0x288/0x600 fs/nfsd/nfsctl.c:436
nfsctl_transaction_write+0x106/0x1a0 fs/nfsd/nfsctl.c:114
vfs_write+0x2aa/0x1050 fs/read_write.c:685
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5577b9e159
RSP: 002b:00007f55789ef028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f5577e26090 RCX: 00007f5577b9e159
RDX: 0000000000000002 RSI: 0000200000000700 RDI: 0000000000000003
RBP: 00007f5577c3503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5577e26128 R14: 00007f5577e26090 R15: 00007fff9f5b3cb8
Showing all locks held in the system:
locks held by khungtaskd/32: 1, last CPU#0:
#0: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6871
locks held by kworker/0:2/191: 5, on CPU#0:
#0: ffff88801fef7140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc90002dc7d08 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
#2: ffff88802abd81d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88802abd81d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bb/0x4420 drivers/usb/core/hub.c:5912
#3: ffff888029fe51d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff888029fe51d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0x10a/0x9a0 drivers/usb/core/hub.c:2341
#4: ffff8880236881a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff8880236881a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
#4: ffff8880236881a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb2/0x620 drivers/base/dd.c:1369
locks held by udevd/4967: 2, last CPU#0:
#0: ffff8880274b23c8 (kn->active#5){++++}-{0:0}, at: kernfs_fop_open+0x59/0xd50 fs/kernfs/file.c:612
#1: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#1: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xbd/0x2090 arch/x86/kernel/unwind_orc.c:495
locks held by getty/5352: 2, on CPU#1:
#0: ffff888033f8c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc9000321e2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
locks held by syz-executor/5595: 4, last CPU#0:
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1542 [inline]
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: copy_mm kernel/fork.c:1595 [inline]
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: copy_process+0x4806/0x8370 kernel/fork.c:2310
#1: ffff888079e05cf8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
#1: ffff888079e05cf8 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x127/0x2370 mm/mmap.c:1716
#2: ffff88801c07d038 (&mm->mmap_lock/1){+.+.}-{4:4}, at: mmap_write_lock_nested include/linux/mmap_lock.h:552 [inline]
#2: ffff88801c07d038 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x1c9/0x2370 mm/mmap.c:1723
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x2f/0x310 mm/pgtable-generic.c:290
locks held by syz-executor/5596: 2, on CPU#0:
#0: ffff888043a160e8 (&type->s_umount_key#84){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff888043a160e8 (&type->s_umount_key#84){++++}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
#0: ffff888043a160e8 (&type->s_umount_key#84){++++}-{4:4}, at: deactivate_super fs/super.c:617 [inline]
#0: ffff888043a160e8 (&type->s_umount_key#84){++++}-{4:4}, at: deactivate_super+0xe2/0x110 fs/super.c:614
#1: ffffffff8f289500 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:582
locks held by syz-executor/5601: 4, last CPU#0:
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1542 [inline]
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: copy_mm kernel/fork.c:1595 [inline]
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: copy_process+0x4806/0x8370 kernel/fork.c:2310
#1: ffff888079e05038 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
#1: ffff888079e05038 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x127/0x2370 mm/mmap.c:1716
#2: ffff8880334a9078 (&mm->mmap_lock/1){+.+.}-{4:4}, at: mmap_write_lock_nested include/linux/mmap_lock.h:552 [inline]
#2: ffff8880334a9078 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x1c9/0x2370 mm/mmap.c:1723
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x2f/0x310 mm/pgtable-generic.c:290
locks held by kworker/0:8/5836: 2, last CPU#0:
#0: ffff88801c05b140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3371
#1: ffffc90004237d08 ((work_completion)(&m->mpeg_thread)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3372
locks held by udevd/5926: 5, last CPU#0:
#0: ffff88807d930460 (sb_writers#6){.+.+}-{0:0}, at: filename_renameat2+0x3af/0xa60 fs/namei.c:6290
#1: ffff88807db150f0 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1069 [inline]
#1: ffff88807db150f0 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3785 [inline]
#1: ffff88807db150f0 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: __start_renaming+0x43b/0x520 fs/namei.c:3878
#2: ffffffff8f909538 (tomoyo_ss){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:198 [inline]
#2: ffffffff8f909538 (tomoyo_ss){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:305 [inline]
#2: ffffffff8f909538 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_read_lock security/tomoyo/common.h:1112 [inline]
#2: ffffffff8f909538 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_path2_perm+0x291/0x700 security/tomoyo/file.c:926
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: prepend_path+0xab/0x1060 fs/d_path.c:164
#4: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#4: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#4: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: prepend_path+0x21e/0x1060 fs/d_path.c:168
locks held by syz.2.1202/9590: 3, on CPU#0:
#0: ffff88807a11dcf0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
#1: ffff88807aae2460 (sb_writers#19){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
#2: ffffffff8f289500 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xa5/0xcc0 fs/nfsd/nfsctl.c:867
locks held by syz.2.1202/9595: 3, on CPU#0:
#0: ffff888079793430 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1259
#1: ffff88807aae2460 (sb_writers#19){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:739
#2: ffffffff8f289500 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x288/0x600 fs/nfsd/nfsctl.c:436
locks held by syz-executor/9780: 4, last CPU#0:
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: dup_mm kernel/fork.c:1542 [inline]
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: copy_mm kernel/fork.c:1595 [inline]
#0: ffffffff8ef3d970 (dup_mmap_sem){++++}-{0:0}, at: copy_process+0x4806/0x8370 kernel/fork.c:2310
#1: ffff88807d3fdcf8 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:562 [inline]
#1: ffff88807d3fdcf8 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x127/0x2370 mm/mmap.c:1716
#2: ffff88801c07e9b8 (&mm->mmap_lock/1){+.+.}-{4:4}, at: mmap_write_lock_nested include/linux/mmap_lock.h:552 [inline]
#2: ffff88801c07e9b8 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x1c9/0x2370 mm/mmap.c:1723
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff8edec4a0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x2f/0x310 mm/pgtable-generic.c:290
locks held by cxacru/11358: 1, on CPU#0:
#0: ffffffff8ec8fda8 (umhelper_sem){++++}-{4:4}, at: usermodehelper_read_trylock+0xab/0x250 kernel/umh.c:212
locks held by syz.5.1866/11788: 1, on CPU#0:
#0: ffffc90006f44450 (&dmxdevfilter->mutex){+.+.}-{4:4}, at: dvb_demux_read+0x55/0x530 drivers/media/dvb-core/dmxdev.c:1038
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2026
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:123
nmi_trigger_cpumask_backtrace+0x21f/0x2a0 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+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+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245