INFO: task syz.7.9271:14937 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.9271 state:D stack:26440 pid:14937 tgid:14934 ppid:4528 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5533 [inline]
__schedule+0x17db/0x58f0 kernel/sched/core.c:7284
__schedule_loop kernel/sched/core.c:7361 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7376
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7433
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821
nfsd_nl_svc_export_get_reqs_dumpit+0xf7/0xc40 fs/nfsd/export.c:674
genl_dumpit+0x10b/0x1b0 net/netlink/genetlink.c:1026
netlink_dump+0x711/0xee0 net/netlink/af_netlink.c:2350
__netlink_dump_start+0x589/0x7b0 net/netlink/af_netlink.c:2465
genl_family_rcv_msg_dumpit+0x213/0x310 net/netlink/genetlink.c:1075
genl_family_rcv_msg net/netlink/genetlink.c:1191 [inline]
genl_rcv_msg+0x5e1/0x7a0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2575
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1364
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800
__sock_sendmsg net/socket.c:815 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2713
___sys_sendmsg+0x2a5/0x360 net/socket.c:2767
__sys_sendmsg net/socket.c:2799 [inline]
__do_sys_sendmsg net/socket.c:2804 [inline]
__se_sys_sendmsg net/socket.c:2802 [inline]
__x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2802
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: 0033:0x7f50cf99e1d9
RSP: 002b:00007f50d080f028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f50cfc26090 RCX: 00007f50cf99e1d9
RDX: 0000000004044810 RSI: 0000200000000180 RDI: 0000000000000008
RBP: 00007f50cfa35888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f50cfc26128 R14: 00007f50cfc26090 R15: 00007ffceeb75d08
Showing all locks held in the system:
locks held by rcu_tasks_kthre/29: 1, on CPU#1:
#0: ffffffff8fd5d248 (rcu_tasks.tasks_gp_mutex){+.+.}-{4:4}, at: rcu_tasks_one_gp+0xb2d/0xe30 kernel/rcu/tasks.h:613
locks held by khungtaskd/33: 1, last CPU#0:
#0: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by kworker/u8:10/1176: 5, last CPU#1:
#0: ffff88801c0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88801c0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88801c0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#0: ffff88801c0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#1: ffffc9000554fc40 ((work_completion)(&port->bc_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc9000554fc40 ((work_completion)(&port->bc_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc9000554fc40 ((work_completion)(&port->bc_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3361 [inline]
#1: ffffc9000554fc40 ((work_completion)(&port->bc_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3479
#2: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#2: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#2: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: macvlan_process_broadcast+0x2e7/0x660 drivers/net/macvlan.c:343
#3: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: skb_dequeue+0x2d/0x160 net/core/skbuff.c:3993
#4: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#4: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#4: ffffffff8fd5c8a0 (rcu_read_lock){....}-{1:3}, at: lapbeth_rcv+0x12f/0x640 drivers/net/wan/lapbether.c:127
locks held by dhcpcd/5282: 1, last CPU#0:
#0: ffff88803513a7f0 (&u->iolock){+.+.}-{4:4}, at: __unix_dgram_recvmsg+0x1e3/0xd70 net/unix/af_unix.c:2587
locks held by getty/5377: 2, on CPU#1:
#0: ffff888032b0d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000323b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by udevd/11824: 1, on CPU#0:
#0: ffff8880282f0350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70 block/bdev.c:990
locks held by syz.0.9262/14916: 2, on CPU#1:
#0: ffffffff912c6408 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff9009f5e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x53d/0x1ab0 fs/nfsd/nfsctl.c:2057
locks held by syz.7.9271/14937: 3, on CPU#0:
#0: ffffffff912c6408 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffff888057ef46e8 (nlk_cb_mutex-GENERIC){+.+.}-{4:4}, at: __netlink_dump_start+0xf4/0x7b0 net/netlink/af_netlink.c:2429
#2: ffffffff9009f5e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_svc_export_get_reqs_dumpit+0xf7/0xc40 fs/nfsd/export.c:674
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 33 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
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/0x480 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
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 1176 Comm: kworker/u8:10 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound macvlan_process_broadcast
RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:1161 [inline]
RIP: 0010:debug_check_no_obj_freed+0x159/0x450 lib/debugobjects.c:1201
Code: dd 16 00 00 41 ff c6 49 89 df 48 85 db 0f 84 39 02 00 00 4d 89 fd 49 c1 ed 03 48 b8 00 00 00 00 00 fc ff df 41 80 7c 05 00 00 <74> 08 4c 89 ff e8 8d af 4c fd 49 8b 1f 4d 8d 67 18 4c 89 e0 48 c1
RSP: 0018:ffffc90000a18920 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: ffff888076d52348 RCX: dffffc0000000001
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90000a18880
RBP: ffff888028270200 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000143110 R12: ffff88802c834520
R13: 1ffff1100edaa469 R14: 0000000000000005 R15: ffff888076d52348
FS: 0000000000000000(0000) GS:ffff888123bc0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055bdf1c4dd71 CR3: 0000000077530000 CR4: 00000000003526f0
Call Trace:
slab_free_hook mm/slub.c:2679 [inline]
slab_free mm/slub.c:6508 [inline]
kfree+0x13e/0x650 mm/slub.c:6801
skb_kfree_head net/core/skbuff.c:1083 [inline]
skb_free_head net/core/skbuff.c:1095 [inline]
skb_release_data+0x82e/0xa80 net/core/skbuff.c:1122
skb_release_all net/core/skbuff.c:1197 [inline]
__kfree_skb+0x5d/0x210 net/core/skbuff.c:1211
lapb_data_input+0xe4e/0x19a0 net/lapb/lapb_in.c:-1
lapb_data_received+0x107/0x1c0 net/lapb/lapb_iface.c:399
lapbeth_rcv+0x34d/0x640 drivers/net/wan/lapbether.c:142
__netif_receive_skb_one_core net/core/dev.c:6297 [inline]
__netif_receive_skb net/core/dev.c:6410 [inline]
process_backlog+0xc26/0x18b0 net/core/dev.c:6761
__napi_poll+0xaa/0x330 net/core/dev.c:7830
napi_poll net/core/dev.c:7893 [inline]
net_rx_action+0x61d/0xf50 net/core/dev.c:8050
handle_softirqs+0x226/0x860 kernel/softirq.c:645
do_softirq+0x77/0xd0 kernel/softirq.c:546
__local_bh_enable_ip+0x100/0x140 kernel/softirq.c:473
local_bh_enable include/linux/bottom_half.h:33 [inline]
netif_rx+0x89/0xa0 net/core/dev.c:5870
macvlan_broadcast+0x375/0x630 drivers/net/macvlan.c:292
macvlan_multicast_rx drivers/net/macvlan.c:-1 [inline]
macvlan_process_broadcast+0x437/0x660 drivers/net/macvlan.c:344
process_one_work kernel/workqueue.c:3396 [inline]
process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
kthread+0x38b/0x480 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