syzbot

INFO: task syz.0.914:9245 blocked for more than 143 seconds.
      Not tainted 6.14.0-rc7-syzkaller-00202-g183601b78a9b #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.914       state:D stack:26072 pid:9245  tgid:9243  ppid:5825   task_flags:0x400040 flags:0x00000004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6914
 __mutex_lock_common kernel/locking/mutex.c:662 [inline]
 __mutex_lock+0x817/0x1010 kernel/locking/mutex.c:730
 nfsd_nl_threads_get_doit+0x1c5/0x7b0 fs/nfsd/nfsctl.c:1713
 genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline]
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0xb1f/0xec0 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x206/0x480 net/netlink/af_netlink.c:2533
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1882
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:733
 ____sys_sendmsg+0x53a/0x860 net/socket.c:2573
 ___sys_sendmsg net/socket.c:2627 [inline]
 __sys_sendmsg+0x269/0x350 net/socket.c:2659
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fedaa18d169
RSP: 002b:00007fedab093038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fedaa3a5fa0 RCX: 00007fedaa18d169
RDX: 0000000000000010 RSI: 0000200000000040 RDI: 0000000000000003
RBP: 00007fedaa20e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fedaa3a5fa0 R15: 00007ffcdc6025b8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8eb393e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8eb393e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8eb393e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6746
2 locks held by getty/5582:
 #0: ffff88814d9090a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fd62f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x616/0x1770 drivers/tty/n_tty.c:2211
3 locks held by kworker/u8:9/6036:
2 locks held by syz.1.667/8461:
 #0: ffffffff8ff27f50 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8ee05948 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x12d/0x1a90 fs/nfsd/nfsctl.c:1922
2 locks held by syz.0.914/9245:
 #0: ffffffff8ff27f50 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8ee05948 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1c5/0x7b0 fs/nfsd/nfsctl.c:1713
1 lock held by syz.6.1328/10625:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.14.0-rc7-syzkaller-00202-g183601b78a9b #0
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+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline]
 watchdog+0x1058/0x10a0 kernel/hung_task.c:399
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5815 Comm: syz-executor Not tainted 6.14.0-rc7-syzkaller-00202-g183601b78a9b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:x64_sys_call+0x59f/0x26b0 arch/x86/entry/syscall_64.c:32
Code: 00 83 fe 3d 0f 8e 41 0c 00 00 83 fe 3f 0f 8f 15 15 00 00 83 fe 3e 0f 84 5a 1c 00 00 83 fe 3f 0f 85 04 21 00 00 e9 b1 18 5e 00 <81> fe e1 00 00 00 0f 8e c4 06 00 00 81 fe e5 00 00 00 0f 8f 29 0c
RSP: 0018:ffffc90003ef7f08 EFLAGS: 00000216
RAX: a310cf5a31250600 RBX: ffffc90003ef7f10 RCX: ffffffff9a61e903
RDX: 0000000000000000 RSI: 00000000000000e6 RDI: ffffc90003ef7f58
RBP: ffffc90003ef7f48 R08: ffffffff903bd177 R09: 1ffffffff2077a2e
R10: dffffc0000000000 R11: fffffbfff2077a2f R12: ffff888035a71e00
R13: 0000000000000000 R14: ffffc90003ef7f58 R15: 00000000000000e6
FS:  000055558d9e9500(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4b04d78ab8 CR3: 0000000035f18000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1c323bf9e3
Code: 1f 84 00 00 00 00 00 83 ff 03 74 7b 83 ff 02 b8 fa ff ff ff 49 89 ca 0f 44 f8 80 3d 5e db 1b 00 00 74 14 b8 e6 00 00 00 0f 05 <f7> d8 c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 ec 28 48 89 54 24 10
RSP: 002b:00007ffc9c3e0168 EFLAGS: 00000202 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1c323bf9e3
RDX: 00007ffc9c3e0180 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000012403ccf R09: 7fffffffffffffff
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffc9c3e05d0
R13: 0000000000000004 R14: 00007ffc9c3e01bc R15: 00007ffc9c3e0250
 </TASK>