INFO: task syz-executor:5780 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:21672 pid:5780  ppid:1      flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 nfsd_shutdown_threads+0x53/0x1a0 fs/nfsd/nfssvc.c:638
 nfsd_umount+0x42/0xc0 fs/nfsd/nfsctl.c:1464
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 cleanup_mnt+0x3d7/0x460 fs/namespace.c:1259
 task_work_run+0x1d4/0x260 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 __syscall_exit_to_user_mode_work kernel/entry/common.c:294 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:305
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f82d6b9f397
RSP: 002b:00007fff6953d5b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f82d6c344bb RCX: 00007f82d6b9f397
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff6953d670
RBP: 00007fff6953d670 R08: 00007fff6953e670 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff6953e700
R13: 00007f82d6c344bb R14: 0000000000027715 R15: 00007fff6953e740
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8d1320e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6635
2 locks held by kworker/u4:9/3475:
4 locks held by kworker/u4:11/3512:
 #0: ffff8880b8e3c258 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x9c/0x130 kernel/sched/core.c:567
 #1: ffff8880b8e28a00 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline]
 #1: ffff8880b8e28a00 (psi_seq){-.-.}-{0:0}, at: __schedule+0x21d3/0x4660 kernel/sched/core.c:6696
 #2: ffff8880b8e295d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999
 #3: ffffffff974e6d50 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x6c/0x500 lib/debugobjects.c:747
2 locks held by getty/5535:
 #0: ffff8880317d20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217
2 locks held by syz-executor/5780:
 #0: ffff888029c3a0e0 (&type->s_umount_key#63){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff888029c3a0e0 (&type->s_umount_key#63){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff888029c3a0e0 (&type->s_umount_key#63){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513
 #1: ffffffff8d3e1c88 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_shutdown_threads+0x53/0x1a0 fs/nfsd/nfssvc.c:638
3 locks held by syz.3.305/6802:
 #0: ffff88802b9c2848 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040
 #1: ffff88807b0ae418 (sb_writers#17){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580
 #2: ffffffff8d3e1c88 (nfsd_mutex){+.+.}-{3:3}, at: write_ports+0xb7/0xfa0 fs/nfsd/nfsctl.c:843
1 lock held by syz.4.722/8216:
1 lock held by syz.1.728/8228:

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf59/0xfa0 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 48 Comm: kworker/u4:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:skb_set_end_offset include/linux/skbuff.h:1649 [inline]
RIP: 0010:__finalize_skb_around net/core/skbuff.c:360 [inline]
RIP: 0010:__build_skb_around+0x155/0x3c0 net/core/skbuff.c:424
Code: 0f 85 a5 01 00 00 41 81 c6 c0 fe ff ff c7 83 c8 00 00 00 00 00 00 00 48 8d 93 cc 00 00 00 49 89 d4 49 c1 ec 03 43 0f b6 04 2c <84> c0 0f 85 93 01 00 00 44 89 b3 cc 00 00 00 48 8d bb ba 00 00 00
RSP: 0018:ffffc90000b8fa80 EFLAGS: 00000a07
RAX: 0000000000000000 RBX: ffff88802568cc80 RCX: ffffffff887d65f5
RDX: ffff88802568cd4c RSI: 0000000000000004 RDI: ffff88802568cd48
RBP: 1ffff11004ad19aa R08: ffff88802568cd67 R09: 1ffff11004ad19ac
R10: dffffc0000000000 R11: ffffed1004ad19ad R12: 1ffff11004ad19a9
R13: dffffc0000000000 R14: 0000000000000ec0 R15: ffff88802568cd64
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2df1aff8 CR3: 000000001d3b6000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 __alloc_skb+0x16f/0x2c0 net/core/skbuff.c:668
 alloc_skb include/linux/skbuff.h:1316 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:748 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:805 [inline]
 nsim_dev_trap_report_work+0x253/0xa90 drivers/net/netdevsim/dev.c:851
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>