INFO: task syz.2.1001:10769 blocked for more than 143 seconds.
      Tainted: G     U              6.15.0-rc3-syzkaller-00001-g9d7a0577c9db #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1001      state:D stack:27688 pid:10769 tgid:10766 ppid:5842   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x116f/0x5de0 kernel/sched/core.c:6767
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x6c7/0xb90 kernel/locking/mutex.c:746
 nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629
 genl_family_rcv_msg_doit+0x206/0x2f0 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x16a/0x440 net/netlink/af_netlink.c:2534
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x53a/0x7f0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 ____sys_sendmsg+0xa95/0xc70 net/socket.c:2566
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
 __sys_sendmsg+0x16d/0x220 net/socket.c:2652
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efe7f38e169
RSP: 002b:00007efe80257038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007efe7f5b6080 RCX: 00007efe7f38e169
RDX: 0000000000000084 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007efe7f410a68 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007efe7f5b6080 R15: 00007ffeffe522d8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e3bf440 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6764
3 locks held by kworker/1:4/5879:
 #0: ffff88801b480d48 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: ffffc9000426fd18 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: ffff88803093d240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1bb/0x2e80 drivers/net/netdevsim/fib.c:1490
5 locks held by kworker/u8:13/6580:
3 locks held by kworker/u8:22/6595:
3 locks held by kworker/u8:49/10053:
 #0: ffff888030f42148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3213
 #1: ffffc900045efd18 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3214
 #2: ffffffff9012c8a8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff9012c8a8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x120/0x14e0 net/ipv6/addrconf.c:4195
2 locks held by syz.2.1001/10767:
 #0: ffffffff901ce950 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7cc028 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629
2 locks held by syz.2.1001/10769:
 #0: ffffffff901ce950 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7cc028 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629
2 locks held by syz-executor/11064:
 #0: ffff8880306ea0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880306ea0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff8880306ea0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff8880306ea0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7cc028 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596
2 locks held by syz.0.1080/11309:
 #0: ffffffff901ce950 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7cc028 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x698/0xbf0 fs/nfsd/nfsctl.c:1629
2 locks held by syz.3.1262/12173:
 #0: ffff88814376e0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88814376e0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88814376e0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff88814376e0e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7cc028 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596
2 locks held by syz.5.1293/12314:
 #0: ffffffff901ce950 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7cc028 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xc4/0x7a0 fs/nfsd/nfsctl.c:1771
2 locks held by syz.1.1373/12730:
 #0: ffff8880913560e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880913560e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff8880913560e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff8880913560e0 (&type->s_umount_key#50){+.+.}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7cc028 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:596
1 lock held by syz-executor/12967:
 #0: ffffffff9012c8a8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff9012c8a8 (rtnl_mutex){+.+.}-{4:4}, at: inet6_rtm_newaddr+0x4e4/0x1c70 net/ipv6/addrconf.c:5028
1 lock held by syz.8.1437/13026:
2 locks held by getty/13087:
 #0: ffff88803649a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900047ab2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
6 locks held by syz.8.1448/13112:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G     U              6.15.0-rc3-syzkaller-00001-g9d7a0577c9db #0 PREEMPT(full) 
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:274 [inline]
 watchdog+0xf70/0x12c0 kernel/hung_task.c:437
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
 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: 13026 Comm: syz.8.1437 Tainted: G     U              6.15.0-rc3-syzkaller-00001-g9d7a0577c9db #0 PREEMPT(full) 
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4855 [inline]
RIP: 0010:__lock_acquire+0x1e4/0x1ba0 kernel/locking/lockdep.c:5185
Code: c0 41 09 c5 8b 84 24 b8 00 00 00 c1 e0 15 41 09 c5 8b 43 20 25 ff 1f 00 00 41 09 c5 8b 84 24 c0 00 00 00 44 89 6b 20 89 43 24 <e8> f7 b0 ff ff 48 89 df 44 0f b6 a8 c4 00 00 00 e8 e7 b0 ff ff 0f
RSP: 0018:ffffc90002fa6e38 EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffff88803655a8f0 RCX: 0000000000020000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88803655a8f0
RBP: ffff88803655a8f0 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: ffffffff8e3bf440 R12: 0000000000000000
R13: 0000000000020007 R14: ffff888036559e00 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881249bf000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32118ff8 CR3: 000000005814a000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lock_acquire kernel/locking/lockdep.c:5866 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5823
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:841 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1155 [inline]
 unwind_next_frame+0xd1/0x20a0 arch/x86/kernel/unwind_orc.c:479
 __unwind_start+0x45f/0x7f0 arch/x86/kernel/unwind_orc.c:758
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0x73/0x100 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 save_stack+0x160/0x1f0 mm/page_owner.c:156
 __reset_page_owner+0x84/0x1a0 mm/page_owner.c:308
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 free_unref_folios+0x999/0x1630 mm/page_alloc.c:2782
 folios_put_refs+0x56f/0x740 mm/swap.c:992
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1125
 shmem_truncate_range mm/shmem.c:1237 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1365
 evict+0x3e3/0x920 fs/inode.c:810
 iput_final fs/inode.c:1898 [inline]
 iput fs/inode.c:1924 [inline]
 iput+0x521/0x880 fs/inode.c:1910
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:457
 __dentry_kill+0x1d0/0x600 fs/dcache.c:660
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:902
 dput+0x1f/0x30 fs/dcache.c:892
 __fput+0x51c/0xb70 fs/file_table.c:473
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xafb/0x2c30 kernel/exit.c:953
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7a0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 irqentry_exit_to_user_mode+0x13f/0x280 kernel/entry/common.c:231
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0033:0x7f0ec8f8e171
Code: Unable to access opcode bytes at 0x7f0ec8f8e147.
RSP: 002b:0000000000000081 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f0ec91b5fa0 RCX: 00007f0ec8f8e169
RDX: 0000200000000080 RSI: 0000000000000081 RDI: 00000000000007ff
RBP: 00007f0ec9010a68 R08: 0000000000000008 R09: 0000000000000000
R10: 00002000000000c0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f0ec91b5fa0 R15: 00007ffdd6cb7b68
 </TASK>