syzbot

INFO: task syz.6.1346:10914 blocked for more than 143 seconds.
      Not tainted 6.12.0-rc7-syzkaller-00189-ge8bdb3c8be08 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.1346      state:D stack:27568 pid:10914 tgid:10905 ppid:9544   flags:0x00000004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5328 [inline]
 __schedule+0xe55/0x5740 kernel/sched/core.c:6693
 __schedule_loop kernel/sched/core.c:6770 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6785
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6842
 __mutex_lock_common kernel/locking/mutex.c:684 [inline]
 __mutex_lock+0x5b8/0x9c0 kernel/locking/mutex.c:752
 nfsd_nl_version_get_doit+0x183/0x780 fs/nfsd/nfsctl.c:1890
 genl_family_rcv_msg_doit+0x202/0x2f0 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x565/0x800 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2536
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1316 [inline]
 netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1342
 netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1886
 sock_sendmsg_nosec net/socket.c:729 [inline]
 __sock_sendmsg net/socket.c:744 [inline]
 ____sys_sendmsg+0xaaf/0xc90 net/socket.c:2607
 ___sys_sendmsg+0x135/0x1e0 net/socket.c:2661
 __sys_sendmsg+0x117/0x1f0 net/socket.c:2690
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f666ed7e719
RSP: 002b:00007f666faca038 EFLAGS: 00000246
 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f666ef36130 RCX: 00007f666ed7e719
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000009
RBP: 00007f666edf175e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f666ef36130 R15: 00007ffd3a48b098
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/30:
 #0: ffffffff8e1b8340 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e1b8340 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1b8340 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x7f/0x390 kernel/locking/lockdep.c:6720
3 locks held by klogd/5187:
 #0: ffff8880b863eed8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:606 [inline]
 #0: ffff8880b863eed8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:591
 #1: ffff88801b0409d8 (&n->list_lock){-.-.}-{2:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #1: ffff88801b0409d8 (&n->list_lock){-.-.}-{2:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffff88801b0409d8 (&n->list_lock){-.-.}-{2:2}, at: page_ext_get+0x34/0x310 mm/page_ext.c:525
 #2: ffff88807a54ae58 (&p->pi_lock){-.-.}-{2:2}, at: class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]
 #2: ffff88807a54ae58 (&p->pi_lock){-.-.}-{2:2}, at: try_to_wake_up+0xa1/0x14f0 kernel/sched/core.c:4165
2 locks held by getty/5577:
 #0: ffff888031eae0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032432f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xfba/0x1480 drivers/tty/n_tty.c:2211
5 locks held by kworker/u8:9/6085:
2 locks held by syz.4.909/9361:
 #0: ffffffff8ff82090 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e5d4f68 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_nl_listener_set_doit+0xe3/0x1b40 fs/nfsd/nfsctl.c:1964
2 locks held by syz.6.1346/10914:
 #0: ffffffff8ff82090 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e5d4f68 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_nl_version_get_doit+0x183/0x780 fs/nfsd/nfsctl.c:1890
3 locks held by syz.5.1787/12531:
 #0: ffffffff8ff82090 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffff8880614e26c8 (nlk_cb_mutex-GENERIC){+.+.}-{3:3}, at: __netlink_dump_start+0x154/0x970 net/netlink/af_netlink.c:2390
 #2: ffffffff8e5d4f68 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_nl_rpc_status_get_dumpit+0xb1/0x1160 fs/nfsd/nfsctl.c:1558

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.12.0-rc7-syzkaller-00189-ge8bdb3c8be08 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
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:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xf0c/0x1240 kernel/hung_task.c:379
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:111