syzbot

INFO: task syz.0.3842:24077 blocked for more than 143 seconds.
      Tainted: G     U              syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.3842      state:D stack:25704 pid:24077 tgid:24073 ppid:5866   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x81b/0x1060 kernel/locking/mutex.c:760
 nfsd_nl_version_get_doit+0x18a/0x800 fs/nfsd/nfsctl.c:1844
 genl_family_rcv_msg_doit+0x209/0x2f0 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2552
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5a7/0x870 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg net/socket.c:729 [inline]
 ____sys_sendmsg+0xa98/0xc70 net/socket.c:2614
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2668
 __sys_sendmsg+0x16d/0x220 net/socket.c:2700
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff6f278ebe9
RSP: 002b:00007ff6f357c038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ff6f29b6180 RCX: 00007ff6f278ebe9
RDX: 0000000020008040 RSI: 00002000000000c0 RDI: 0000000000000003
RBP: 00007ff6f2811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff6f29b6218 R14: 00007ff6f29b6180 R15: 00007ffdd463da18
 </TASK>
INFO: task syz.3.3856:24184 blocked for more than 143 seconds.
      Tainted: G     U              syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.3856      state:D stack:28872 pid:24184 tgid:24182 ppid:5865   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x81b/0x1060 kernel/locking/mutex.c:760
 tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
 chrdev_open+0x234/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x982/0x1530 fs/open.c:965
 vfs_open+0x82/0x3f0 fs/open.c:1095
 do_open fs/namei.c:3887 [inline]
 path_openat+0x1de4/0x2cb0 fs/namei.c:4046
 do_filp_open+0x20b/0x470 fs/namei.c:4073
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x174/0x210 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0ad7d8ebe9
RSP: 002b:00007f0ad5fd5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f0ad7fb6090 RCX: 00007f0ad7d8ebe9
RDX: 0000000000002200 RSI: 0000200000000440 RDI: ffffffffffffff9c
RBP: 00007f0ad7e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0ad7fb6128 R14: 00007f0ad7fb6090 R15: 00007ffe95fcb338
 </TASK>
INFO: task syz.1.3857:24187 blocked for more than 143 seconds.
      Tainted: G     U              syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.3857      state:D stack:28232 pid:24187 tgid:24185 ppid:5867   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x81b/0x1060 kernel/locking/mutex.c:760
 tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
 chrdev_open+0x234/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x982/0x1530 fs/open.c:965
 vfs_open+0x82/0x3f0 fs/open.c:1095
 do_open fs/namei.c:3887 [inline]
 path_openat+0x1de4/0x2cb0 fs/namei.c:4046
 do_filp_open+0x20b/0x470 fs/namei.c:4073
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x174/0x210 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf53d8ebe9
RSP: 002b:00007fbf54c0b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fbf53fb5fa0 RCX: 00007fbf53d8ebe9
RDX: 0000000000002200 RSI: 0000200000000440 RDI: ffffffffffffff9c
RBP: 00007fbf53e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbf53fb6038 R14: 00007fbf53fb5fa0 R15: 00007ffd0f857ec8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/32:
 #0: ffffffff8e5c10a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5c10a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e5c10a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by kworker/u10:1/17533:
 #0: ffff888020ba0948 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc9000434fd10 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u10:4/17548:
 #0: ffff888020ba0948 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc9000afa7d10 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
3 locks held by kworker/u10:5/17558:
2 locks held by kworker/u10:6/17559:
 #0: ffff888020ba0948 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90003f7fd10 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by kworker/u10:7/17560:
 #0: ffff888020ba0948 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc9000453fd10 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
2 locks held by getty/23242:
 #0: ffff8880314a40a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002e442f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
2 locks held by syz.0.3842/24074:
2 locks held by syz.0.3842/24077:
 #0: ffffffff9042a310 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e9d9788 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x18a/0x800 fs/nfsd/nfsctl.c:1844
4 locks held by syz.2.3855/24176:
1 lock held by syz.3.3856/24184:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.1.3857/24187:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.4.3861/24238:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.6.3863/24337:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.7.3866/24338:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.7.3866/24340:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.5.3867/24351:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
2 locks held by kworker/u10:8/24371:
 #0: ffff888020ba0948 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90003d2fd10 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
1 lock held by syz.9.3875/24494:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:823 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0xff/0x360 drivers/tty/pty.c:790
2 locks held by kworker/u10:11/24517:
 #0: ffff88801b889148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
 #1: ffffc90000127d10 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
1 lock held by syz.2.3878/24531:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.2.3878/24533:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.1.3892/24643:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.0.3893/24642:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.3.3881/24676:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.4.3897/24706:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.4.3897/24707:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
8 locks held by syz-executor/24769:
2 locks held by syz.6.3903/24809:
1 lock held by syz.7.3905/24825:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by syz.7.3905/24826:
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2cba88 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x53e/0xf90 drivers/tty/tty_io.c:2120
1 lock held by modprobe/24828:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Tainted: G     U              syzkaller #0 PREEMPT(full) 
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf0e/0x1260 kernel/hung_task.c:491
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>