syzbot

INFO: task syz.2.5165:25473 blocked for more than 144 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.5165      state:D stack:27288 pid:25473 tgid:25471 ppid:24545  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 schedule_timeout+0x1b2/0x280 kernel/time/sleep_timeout.c:75
 ___down_common kernel/locking/semaphore.c:289 [inline]
 __down_common+0x371/0x8a0 kernel/locking/semaphore.c:314
 down+0x74/0xa0 kernel/locking/semaphore.c:100
 console_lock+0x5b/0xa0 kernel/printk/printk.c:2896
 class_console_lock_constructor include/linux/console.h:736 [inline]
 con_install+0x99/0x620 drivers/tty/vt/vt.c:3742
 tty_driver_install_tty drivers/tty/tty_io.c:1295 [inline]
 tty_init_dev.part.0+0x9e/0x470 drivers/tty/tty_io.c:1407
 tty_init_dev include/linux/err.h:78 [inline]
 tty_open_by_driver drivers/tty/tty_io.c:2073 [inline]
 tty_open+0xa63/0xfa0 drivers/tty/tty_io.c:2120
 chrdev_open+0x234/0x6a0 fs/char_dev.c:411
 do_dentry_open+0x6d8/0x1660 fs/open.c:947
 vfs_open+0x82/0x3f0 fs/open.c:1079
 do_open fs/namei.c:4699 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4858
 do_file_open+0x20e/0x430 fs/namei.c:4887
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4c2c75d60e
RSP: 002b:00007f4c2d6b1b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4c2d6b26c0 RCX: 00007f4c2c75d60e
RDX: 0000000000000002 RSI: 00007f4c2d6b1c00 RDI: ffffffffffffff9c
RBP: 00007f4c2c832d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4c2ca16038 R14: 00007f4c2ca15fa0 R15: 00007ffecb36d258
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e7e54e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e7e54e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8e7e54e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:5/113:
2 locks held by getty/5364:
 #0: ffff8880395670a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14f0 drivers/tty/n_tty.c:2211
3 locks held by kworker/0:15/17554:
 #0: ffff88813fe5b140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277
 #1: ffffc900066ffd08 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278
 #2: ffff88801ee8e230 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1b8/0x63b0 drivers/net/netdevsim/fib.c:1490
2 locks held by kworker/1:1/22179:
 #0: ffff88813fe5b140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x12d6/0x1980 kernel/workqueue.c:3277
 #1: ffffc900042dfd08 (console_work){+.+.}-{0:0}, at: process_one_work+0x973/0x1980 kernel/workqueue.c:3278
2 locks held by syz.0.5069/24735:
3 locks held by kworker/u8:6/24908:
2 locks held by syz.2.5165/25473:
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
 #1: ffff88806b78b1b0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x39/0x470 drivers/tty/tty_io.c:1406
1 lock held by syz.3.5207/25894:
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:800 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x11a/0x370 drivers/tty/pty.c:767
1 lock held by syz.7.5274/26475:
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.5.5289/26573:
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:800 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x11a/0x370 drivers/tty/pty.c:767
1 lock held by syz.0.5378/27163:
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.0.5378/27174:
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:800 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x11a/0x370 drivers/tty/pty.c:767
1 lock held by syz-executor/27348:
 #0: ffffffff9060aa20 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff9060aa20 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x30c/0x18b0 net/ipv4/devinet.c:978
2 locks held by syz.9.5440/27513:
 #0: ffff888034cf14e0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
 #0: ffff888034cf14e0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: sctp_sendmsg+0xfd6/0x22b0 net/sctp/socket.c:1969
 #1: ffffffff8e7e54e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #1: ffffffff8e7e54e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #1: ffffffff8e7e54e0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
 #1: ffffffff8e7e54e0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xbd/0x2090 arch/x86/kernel/unwind_orc.c:495
1 lock held by syz.9.5440/27520:
 #0: ffff888034cf14e0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
 #0: ffff888034cf14e0 (sk_lock-AF_INET6){+.+.}-{0:0}, at: sctp_setsockopt+0x593/0xb370 net/sctp/socket.c:4599
3 locks held by syz.9.5440/27523:
2 locks held by syz.6.5441/27507:
1 lock held by syz.6.5441/27510:
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:800 [inline]
 #0: ffffffff8f500cc0 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x11a/0x370 drivers/tty/pty.c:767
1 lock held by syz.1.5442/27518:
3 locks held by rm/27519:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 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 lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 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+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xcb1/0x1030 kernel/hung_task.c:561
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 27518 Comm: syz.1.5442 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:check_preemption_disabled+0x1c/0xe0 lib/smp_processor_id.c:54
Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 41 54 55 53 48 83 ec 08 65 8b 1d 65 b8 80 08 65 f7 05 56 b8 80 08 ff ff ff 7f 74 0f <48> 83 c4 08 89 d8 5b 5d 41 5c c3 cc cc cc cc 9c 58 f6 c4 02 74 ea
RSP: 0018:ffffc9000750f9a0 EFLAGS: 00000046
RAX: 0000000000000046 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8e00fe74 RDI: ffffffff8c1c3480
RBP: ffffffff82595955 R08: 0000000000000001 R09: 00000000000001c8
R10: 0000000000000200 R11: 0000000000000000 R12: ffff888028b12500
R13: ffffffff82595955 R14: 0000000000000287 R15: dffffc0000000000
FS:  00007f7c95c606c0(0000) GS:ffff888124479000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbce07e3000 CR3: 0000000064b74000 CR4: 00000000003526f0
DR0: 0000000000000004 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lockdep_recursion_inc kernel/locking/lockdep.c:465 [inline]
 lock_release kernel/locking/lockdep.c:5888 [inline]
 lock_release+0x9a/0x310 kernel/locking/lockdep.c:5875
 __might_fault+0x10c/0x140 mm/memory.c:7324
 _inline_copy_from_user include/linux/uaccess.h:169 [inline]
 _copy_from_user+0x29/0xd0 lib/usercopy.c:18
 copy_from_user include/linux/uaccess.h:223 [inline]
 copy_msghdr_from_user+0x9f/0x4f0 net/socket.c:2628
 recvmsg_copy_msghdr net/socket.c:2884 [inline]
 ___sys_recvmsg+0xdd/0x1a0 net/socket.c:2956
 do_recvmmsg+0x301/0x760 net/socket.c:3055
 __sys_recvmmsg net/socket.c:3129 [inline]
 __do_sys_recvmmsg net/socket.c:3152 [inline]
 __se_sys_recvmmsg net/socket.c:3145 [inline]
 __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3145
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7c94d9cdd9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7c95c60028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f7c95015fa0 RCX: 00007f7c94d9cdd9
RDX: 00000000080002c1 RSI: 0000200000000040 RDI: 0000000000000004
RBP: 00007f7c94e32d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7c95016038 R14: 00007f7c95015fa0 R15: 00007fff461cfb18
 </TASK>