INFO: task syz.4.3437:18125 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.3437 state:D stack:25768 pid:18125 tgid:18124 ppid:15856 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0x1585/0x5340 kernel/sched/core.c:6907
__schedule_loop kernel/sched/core.c:6989 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7004
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7061
__mutex_lock_common kernel/locking/mutex.c:692 [inline]
__mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
nfsd_nl_version_set_doit+0xcd/0x7a0 fs/nfsd/nfsctl.c:1743
genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2592
___sys_sendmsg+0x2a5/0x360 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9067f9c799
RSP: 002b:00007f9068dc1028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9068215fa0 RCX: 00007f9067f9c799
RDX: 0000000004008090 RSI: 0000200000000140 RDI: 000000000000000a
RBP: 00007f9068032bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9068216038 R14: 00007f9068215fa0 R15: 00007ffcfd462068
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e7602e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#0: ffffffff8e7602e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#0: ffffffff8e7602e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5580:
#0: ffff888036de00a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0 drivers/tty/n_tty.c:2211
2 locks held by syz.0.1524/11200:
#0: ffffffff8fc3a670 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ea86c28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x16c0 fs/nfsd/nfsctl.c:1893
2 locks held by syz.4.3437/18125:
#0: ffffffff8fc3a670 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ea86c28 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xcd/0x7a0 fs/nfsd/nfsctl.c:1743
5 locks held by kworker/u8:42/21222:
1 lock held by syz.5.5327/24314:
#0: ffffffff8e766440 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x580 kernel/rcu/tree.c:3828
1 lock held by syz.3.5328/24318:
#0: ffffffff8e766578 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
#0: ffffffff8e766578 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770 kernel/rcu/tree_exp.h:961
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:161 [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:346 [inline]
watchdog+0xfd9/0x1030 kernel/hung_task.c:515
kthread+0x388/0x470 kernel/kthread.c:467
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 24315 Comm: syz.5.5327 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:PageBuddy include/linux/page-flags.h:1003 [inline]
RIP: 0010:page_is_buddy mm/internal.h:720 [inline]
RIP: 0010:find_buddy_page_pfn mm/internal.h:785 [inline]
RIP: 0010:buddy_merge_likely mm/page_alloc.c:939 [inline]
RIP: 0010:__free_one_page+0x59d/0xbd0 mm/page_alloc.c:1057
Code: 49 29 ec 49 c1 e4 06 4c 89 f9 4f 8d 3c 2c 49 83 c7 30 4c 89 f8 48 c1 e8 03 0f b6 04 08 84 c0 0f 85 58 04 00 00 41 0f b6 47 03 e0 18 3d 00 00 00 f0 0f 85 00 01 00 00 4d 01 ec 8d 6b 01 4d 8d
RSP: 0018:ffffc90004a9f5e0 EFLAGS: 00000046
RAX: 00000000000000ff RBX: 0000000000000001 RCX: dffffc0000000000
RDX: 0000000000000017 RSI: 0000000000053dc7 RDI: ffffea00014f71a8
RBP: 0000000000053dc4 R08: ffffea00014f71f7 R09: 1ffffd400029ee3e
R10: dffffc0000000000 R11: fffff9400029ee3f R12: ffffffffffffff00
R13: ffffea00014f7100 R14: ffffea00014f7180 R15: ffffea00014f7030
FS: 0000000000000000(0000) GS:ffff888125464000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcc9977e0c CR3: 0000000048020000 CR4: 00000000003526f0
Call Trace:
free_pcppages_bulk+0x2de/0x520 mm/page_alloc.c:1531
free_frozen_page_commit+0x62a/0x1220 mm/page_alloc.c:2915
__free_frozen_pages+0x6f0/0xdb0 mm/page_alloc.c:3005
tlb_batch_list_free mm/mmu_gather.c:161 [inline]
tlb_finish_mmu+0x144/0x230 mm/mmu_gather.c:533
exit_mmap+0x498/0xa10 mm/mmap.c:1315
__mmput+0x118/0x430 kernel/fork.c:1174
exit_mm+0x168/0x220 kernel/exit.c:581
do_exit+0x62e/0x2320 kernel/exit.c:959
do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
get_signal+0x1284/0x1330 kernel/signal.c:3034
arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff7d2d9c799
Code: Unable to access opcode bytes at 0x7ff7d2d9c76f.
RSP: 002b:00007ff7d3c810e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007ff7d3015fa8 RCX: 00007ff7d2d9c799
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007ff7d3015fa8
RBP: 00007ff7d3015fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff7d3016038 R14: 00007fffc20b6bd0 R15: 00007fffc20b6cb8