syzbot

INFO: task syz.2.8777:25857 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.8777      state:D stack:26648 pid:25857 tgid:25856 ppid:5647   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7283
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7340
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x7f7/0x1550 kernel/locking/mutex.c:820
 nfsd_nl_version_set_doit+0xcd/0x7a0 fs/nfsd/nfsctl.c:1788
 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+0x75c/0x8e0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
 __sys_sendmsg net/socket.c:2784 [inline]
 __do_sys_sendmsg net/socket.c:2789 [inline]
 __se_sys_sendmsg net/socket.c:2787 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd11c99ce59
RSP: 002b:00007fd11d82a028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd11cc15fa0 RCX: 00007fd11c99ce59
RDX: 0000000004008090 RSI: 0000200000000140 RDI: 0000000000000003
RBP: 00007fd11ca32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd11cc16038 R14: 00007fd11cc15fa0 R15: 00007ffe7690e198
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/32:
 #0: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by pvrusb2-context/2357:
 #0: ffff88802ac08180 (&hdw->big_lock_mutex){+.+.}-{4:4}, at: pvr2_hdw_initialize+0xe4/0x3c50 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2326
 #1: ffffffff8e7f99e8 (umhelper_sem){++++}-{4:4}, at: usermodehelper_read_trylock+0xfc/0x2c0 kernel/umh.c:214
2 locks held by getty/5378:
 #0: ffff8880368a80a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0 drivers/tty/n_tty.c:2211
4 locks held by syz-executor/5657:
 #0: ffff8880b863aea0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:652
 #1: ffff8880b8624588 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880 kernel/sched/psi.c:933
 #2: ffff888068b8c398 (&sb->s_type->i_lock_key#10){+.+.}-{3:3}, at: spin_trylock include/linux/spinlock.h:354 [inline]
 #2: ffff888068b8c398 (&sb->s_type->i_lock_key#10){+.+.}-{3:3}, at: lock_for_kill+0x84/0x210 fs/dcache.c:763
 #3: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #3: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #3: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: percpu_ref_tryget_many include/linux/percpu-refcount.h:241 [inline]
 #3: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: percpu_ref_tryget+0x15/0x180 include/linux/percpu-refcount.h:266
6 locks held by kworker/0:1/13485:
 #0: ffff8880222f7140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3289 [inline]
 #0: ffff8880222f7140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3397
 #1: ffffc90005d3fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3290 [inline]
 #1: ffffc90005d3fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3397
 #2: ffff88802a4991d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1040 [inline]
 #2: ffff88802a4991d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x17f/0x4f30 drivers/usb/core/hub.c:5899
 #3: ffff8880344131d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1040 [inline]
 #3: ffff8880344131d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xf8/0x990 drivers/usb/core/hub.c:2336
 #4: ffff88803281b1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1040 [inline]
 #4: ffff88803281b1a0 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1174 [inline]
 #4: ffff88803281b1a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb6/0x870 drivers/base/dd.c:1372
 #5: ffff88802ac08180 (&hdw->big_lock_mutex){+.+.}-{4:4}, at: pvr2_hdw_disconnect+0x6d/0x500 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2708
2 locks held by syz.4.6927/21648:
 #0: ffffffff8fe412e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec8b220 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670 fs/nfsd/nfsctl.c:1938
2 locks held by syz.2.8777/25857:
 #0: ffffffff8fe412e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec8b220 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xcd/0x7a0 fs/nfsd/nfsctl.c:1788
2 locks held by syz.0.9867/28261:
 #0: ffffffff8fe412e8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec8b220 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x141/0x1670 fs/nfsd/nfsctl.c:1938
1 lock held by syz.7.10434/29655:
 #0: ffff88802a4991d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1040 [inline]
 #0: ffff88802a4991d8 (&dev->mutex){....}-{4:4}, at: usbdev_open+0x182/0x770 drivers/usb/core/devio.c:1054

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 32 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 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:162 [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+0xfd3/0x1030 kernel/hung_task.c:561
 kthread+0x389/0x470 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
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 22181 Comm: syz-executor Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:hrtimer_interrupt+0x7c/0x950 kernel/time/hrtimer.c:2090
Code: 48 89 d8 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 89 85 7e 00 4c 8b 3b 49 8d 9f cc 12 3a 93 48 89 d8 48 c1 e8 03 0f b6 04 28 <84> c0 0f 85 d6 07 00 00 80 3b 00 0f 84 b0 08 00 00 4d 8d a7 80 12
RSP: 0018:ffffc90000007ea0 EFLAGS: 00000017
RAX: 0000000000000000 RBX: ffff8880b86282cc RCX: ffff888033a70000
RDX: 0000000000010000 RSI: 0000000000000000 RDI: 0000000000000008
RBP: dffffc0000000000 R08: ffffffff9030daf7 R09: 1ffffffff2061b5e
R10: dffffc0000000000 R11: ffffffff81b27060 R12: dffffc0000000000
R13: 0000000000000000 R14: ffff8880b8623e40 R15: ffff888125287000
FS:  000055558a6d8500(0000) GS:ffff888125287000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f24b09ea2f8 CR3: 0000000076dab000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:2039 [inline]
RIP: 0010:vprintk_emit+0x45d/0x560 kernel/printk/printk.c:2478
Code: 0f 84 44 ff ff ff e8 d2 29 21 00 fb eb 44 e8 ca 29 21 00 e8 e5 d8 04 0a 4d 85 f6 74 94 e8 bb 29 21 00 fb 48 c7 c7 c0 f0 94 8e <31> f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 53 e8 cb 18
RSP: 0018:ffffc9000ea77960 EFLAGS: 00000293
RAX: ffffffff81a48c45 RBX: ffffffff81a48abf RCX: ffff888033a70000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e94f0c0
RBP: ffffc9000ea77a10 R08: ffffffff9030daf7 R09: 1ffffffff2061b5e
R10: dffffc0000000000 R11: fffffbfff2061b5f R12: 0000000000000000
R13: 000000000000004c R14: 0000000000000200 R15: 1ffff92001d4ef30
 _printk+0xdd/0x130 kernel/printk/printk.c:2504
 __ext4_msg+0x2b9/0x2d0 fs/ext4/super.c:1001
 ext4_put_super+0xb6/0xd80 fs/ext4/super.c:1302
 generic_shutdown_super+0x13d/0x2d0 fs/super.c:646
 kill_block_super+0x44/0x90 fs/super.c:1725
 ext4_kill_sb+0x68/0xb0 fs/ext4/super.c:7492
 deactivate_locked_super+0xbc/0x130 fs/super.c:476
 cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xf3/0x4d0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f01a699e097
Code: a2 c7 05 5c 06 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fff2d772a58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f01a6a321ca RCX: 00007f01a699e097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff2d772b10
RBP: 00007fff2d772b10 R08: 00007fff2d773b10 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff2d773ba0
R13: 00007f01a6a321ca R14: 00000000000ed019 R15: 00007fff2d773be0
 </TASK>