INFO: task syz.6.789:8627 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.789       state:D stack:27464 pid:8627  tgid:8621  ppid:6181   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5533 [inline]
 __schedule+0x16d9/0x5700 kernel/sched/core.c:7284
 __schedule_loop kernel/sched/core.c:7361 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7668
 rt_mutex_slowlock_block+0x55e/0x690 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
 mutex_lock_nested+0x168/
 __rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:562 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:580
 write_threads+0x3b4/0x610 fs/nfsd/nfsctl.c:436
 nfsctl_transaction_write+0x112/0x160 fs/nfsd/nfsctl.c:114
 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+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1f4ce3e159
RSP: 002b:00007f1f4b075028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1f4d0c6090 RCX: 00007f1f4ce3e159
RDX: 0000000000000002 RSI: 0000200000000200 RDI: 0000000000000003
RBP: 00007f1f4ced506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1f4d0c6128 R14: 00007f1f4d0c6090 R15: 00007ffd0693fc98
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/38: 1, last CPU#1:
 #0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by dhcpcd/5248: 2, last CPU#1:
 #0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: sock_def_readable+0xae/0x550 net/core/sock.c:3665
 #1: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #1: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57
locks held by getty/5338: 2, on CPU#1:
 #0: ffff8880359930a0 (&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/u8:29/6021: 4, on CPU#0:
 #0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #0: ffff88801aeb0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #1: ffffc900068c7c40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffc900068c7c40 (net_cleanup_work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffc900068c7c40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
 #1: ffffc900068c7c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
 #2: ffffffff8f5c67e0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810 net/core/net_namespace.c:677
 #3: ffff888088261978 (&wg->device_update_lock){+.+.}-{4:4}, at: wg_destruct+0x116/0x310 drivers/net/wireguard/device.c:249
locks held by syz.6.789/8623: 3, on CPU#0:
 #0: ffff8880371b1d28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
 #1: ffff888025768510 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
 #1: ffff888025768510 (sb_writers#12){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
 #2: ffffffff8e4f8458 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd20 fs/nfsd/nfsctl.c:867
locks held by syz.6.789/8627: 3, on CPU#1:
 #0: ffff888033e0cf28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1259
 #1: ffff888025768510 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
 #1: ffff888025768510 (sb_writers#12){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
 #2: ffffffff8e4f8458 (nfsd_mutex){+.+.}-{4:4}, at: write_threads+0x3b4/0x610 fs/nfsd/nfsctl.c:436
locks held by syz-executor/11702: 7, on CPU#0:
 #0: ffff888036800510 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
 #0: ffff888036800510 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x231/0xbb0 fs/read_write.c:683
 #1: ffff88804ef4d078 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d9/0x540 fs/kernfs/file.c:336
 #2: ffff888029424b48 (kn->active#51){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #2: ffff888029424b48 (kn->active#51){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22c/0x540 fs/kernfs/file.c:337
 #3: ffffffff8ee454b8 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd6/0x370 drivers/net/netdevsim/bus.c:234
 #4: ffff88805f976160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
 #4: ffff88805f976160 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
 #4: ffff88805f976160 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880 drivers/base/dd.c:1369
 #5: ffff888020b92310 (&devlink->lock_key){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x160 drivers/net/netdevsim/dev.c:1724
 #6: ffffffff8e1c9f30 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x530 kernel/rcu/tree.c:3904
locks held by syz.7.1896/12060: 2, on CPU#1:
 #0: ffff88801b3e8510 (sb_writers#19){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x210 fs/namespace.c:538
 #1: ffff88805fd6a278 (&sb->s_type->i_mutex_key#32){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #1: ffff88805fd6a278 (&sb->s_type->i_mutex_key#32){+.+.}-{4:4}, at: vfs_setxattr+0x13e/0x360 fs/xattr.c:343
locks held by syz.4.1899/12081: 2, on CPU#0:
 #0: ffff88802278e510 (sb_writers#19){.+.+}-{0:0}, at: mnt_want_write_file+0x63/0x210 fs/namespace.c:538
 #1: ffff88805fd69a38 (&sb->s_type->i_mutex_key#32){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #1: ffff88805fd69a38 (&sb->s_type->i_mutex_key#32){+.+.}-{4:4}, at: vfs_setxattr+0x13e/0x360 fs/xattr.c:343
locks held by syz.4.1899/12084: 2, on CPU#0:
 #0: ffff88802278e510 (sb_writers#19){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:494
 #1: ffff88805fd69a38 (&sb->s_type->i_mutex_key#32){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1024 [inline]
 #1: ffff88805fd69a38 (&sb->s_type->i_mutex_key#32){+.+.}-{4:4}, at: vfs_setxattr+0x13e/0x360 fs/xattr.c:343
locks held by syz.9.1907/12096: 4, last CPU#0:
 #0: ffff88803b6aba30 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:600 [inline]
 #0: ffff88803b6aba30 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x1a4/0x9f0 mm/mmap.c:1299
 #1: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #1: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290
 #2: ffff8880a3d21658 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #2: ffff8880a3d21658 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:404
 #3: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
 #3: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #3: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #3: ffffffff8e1c3cc0 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e2/0x400 kernel/locking/spinlock_rt.c:57

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 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:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x38b/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
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 12096 Comm: syz.9.1907 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:memset+0x0/0x30 arch/x86/lib/memset_64.S:32
Code: 89 54 17 fe eb 0c 48 83 fa 01 72 06 44 8a 1e 44 88 1f e9 c3 ac 03 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa eb 2a 49 89 f9 40 88 f0 48 89 d1 f3 aa 4c 89 c8 e9 97
RSP: 0018:ffffc900049cf318 EFLAGS: 00000202
RAX: ffffc900049cf901 RBX: ffffc900049cf418 RCX: ffffffff8177fe34
RDX: 0000000000000010 RSI: 0000000000000000 RDI: ffffc900049cf418
RBP: 1ffffffff209e558 R08: ffffc900049cf427 R09: 1ffff92000939e84
R10: dffffc0000000000 R11: fffff52000939e85 R12: dffffc0000000000
R13: ffffffff904f2abc R14: ffffc900049cf3c8 R15: ffffc900049cf410
FS:  0000000000000000(0000) GS:ffff888125bc8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33321ff8 CR3: 00000000409a0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 unwind_next_frame+0xd04/0x2550 arch/x86/kernel/unwind_orc.c:621
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3181 [inline]
 call_rcu+0xee/0x8b0 kernel/rcu/tree.c:3301
 slab_free_hook mm/slub.c:2712 [inline]
 slab_free mm/slub.c:6508 [inline]
 kmem_cache_free+0x539/0x6d0 mm/slub.c:6635
 anon_vma_free mm/rmap.c:137 [inline]
 __put_anon_vma+0x12a/0x310 mm/rmap.c:2970
 put_anon_vma mm/internal.h:290 [inline]
 unlink_anon_vmas+0x544/0x720 mm/rmap.c:536
 free_pgtables+0x836/0xb70 mm/memory.c:414
 exit_mmap+0x4aa/0x9f0 mm/mmap.c:1327
 __mmput+0xcb/0x3d0 kernel/fork.c:1193
 exit_mm+0x186/0x240 kernel/exit.c:618
 do_exit+0x6cd/0x2360 kernel/exit.c:1000
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1155
 __do_sys_exit_group kernel/exit.c:1166 [inline]
 __se_sys_exit_group kernel/exit.c:1164 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1164
 x64_sys_call+0x18c6/0x18d0 arch/x86/include/generated/asm/syscalls_64.h:232
 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: 0033:0x7f3a2fcbe159
Code: Unable to access opcode bytes at 0x7f3a2fcbe12f.
RSP: 002b:00007ffdf14705a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3a2fcbe159
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffdf147060c R08: 0000000000000000 R09: 00000000000927c0
R10: 00007f3a2ff46128 R11: 0000000000000246 R12: 0000000000000123
R13: 00000000000927c0 R14: 000000000006dde4 R15: 00007ffdf1470660
 </TASK>