INFO: task syz.4.1784:18201 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.4.1784 state:D stack:26536 pid:18201 tgid:18197 ppid:11368 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5295 [inline]
__schedule+0xfee/0x6120 kernel/sched/core.c:6908
__schedule_loop kernel/sched/core.c:6990 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:7005
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
rwsem_down_write_slowpath+0x530/0x1280 kernel/locking/rwsem.c:1185
__down_write_common kernel/locking/rwsem.c:1317 [inline]
__down_write kernel/locking/rwsem.c:1326 [inline]
down_write+0x1c7/0x1f0 kernel/locking/rwsem.c:1591
class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
n_tty_flush_buffer+0x1f/0x140 drivers/tty/n_tty.c:349
tty_buffer_flush+0x239/0x310 drivers/tty/tty_buffer.c:241
tty_ldisc_flush+0x68/0xf0 drivers/tty/tty_ldisc.c:388
vt_k_ioctl drivers/tty/vt/vt_ioctl.c:400 [inline]
vt_ioctl+0x104f/0x31a0 drivers/tty/vt/vt_ioctl.c:743
tty_ioctl+0x26a/0x1690 drivers/tty/tty_io.c:2792
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf6db9c799
RSP: 002b:00007fbf6bdd5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fbf6de16090 RCX: 00007fbf6db9c799
RDX: 0000000000000003 RSI: 0000000000004b45 RDI: 0000000000000004
RBP: 00007fbf6dc32c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbf6de16128 R14: 00007fbf6de16090 R15: 00007ffe254830d8
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e7e75a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#0: ffffffff8e7e75a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#0: ffffffff8e7e75a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by getty/5563:
#0: ffff88823be780a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
3 locks held by kworker/0:7/5885:
2 locks held by kworker/u8:11/8105:
#0: ffff88813fe9c948 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work+0x1287/0x1920 kernel/workqueue.c:3250
#1: ffffc9001b137d08 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x93c/0x1920 kernel/workqueue.c:3251
2 locks held by kworker/u8:13/8111:
#0: ffff88813fe9c948 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work+0x1287/0x1920 kernel/workqueue.c:3250
#1: ffffc9000fc3fd08 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x93c/0x1920 kernel/workqueue.c:3251
3 locks held by kworker/0:6/15208:
6 locks held by syz.5.1761/17979:
3 locks held by syz.4.1784/18201:
#0: ffff88802c51d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref drivers/tty/tty_ldisc.c:263 [inline]
#0: ffff88802c51d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_flush+0x1c/0xf0 drivers/tty/tty_ldisc.c:386
#1: ffff88801ba820b8 (&buf->lock){+.+.}-{4:4}, at: tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:229
#2: ffff88802c51d2e8 (&tty->termios_rwsem){++++}-{4:4}, at: class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
#2: ffff88802c51d2e8 (&tty->termios_rwsem){++++}-{4:4}, at: n_tty_flush_buffer+0x1f/0x140 drivers/tty/n_tty.c:349
2 locks held by kworker/u8:4/18978:
#0: ffff88813fe9c148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1287/0x1920 kernel/workqueue.c:3250
#1: ffffc9000545fd08 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_one_work+0x93c/0x1920 kernel/workqueue.c:3251
2 locks held by syz.2.2100/19857:
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
#1: ffff88807abc61c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x39/0x470 drivers/tty/tty_io.c:1406
1 lock held by syz.8.2116/19943:
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.1.2183/20348:
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.6.2192/20406:
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline]
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765
1 lock held by syz.5.2213/20579:
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
#0: ffffffff8f4ec528 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
3 locks held by syz.3.2251/20866:
2 locks held by syz.4.2253/20882:
1 lock held by modprobe/20879:
4 locks held by dhcpcd-run-hook/20880:
2 locks held by modprobe/20881:
=============================================
NMI backtrace for cpu 1
CPU: 1 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 02/27/2026
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:161 [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:346 [inline]
watchdog+0xd25/0x1050 kernel/hung_task.c:515
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x754/0xd80 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: 20882 Comm: syz.4.2253 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
RIP: 0010:lockdep_recursion_inc kernel/locking/lockdep.c:465 [inline]
RIP: 0010:lock_release kernel/locking/lockdep.c:5888 [inline]
RIP: 0010:lock_release+0x8e/0x320 kernel/locking/lockdep.c:5875
Code: 00 65 4c 8b 25 2b c8 28 12 41 8b bc 24 54 0b 00 00 85 ff 0f 85 21 01 00 00 48 81 3b 40 87 14 94 0f 84 14 01 00 00 9c 41 5e fa <48> c7 c7 d8 7d f6 8d e8 f6 0c ab 09 65 ff 05 67 0f 29 12 8b 35 dd
RSP: 0018:ffffc9000ea8f9c8 EFLAGS: 00000087
RAX: 0000000000000000 RBX: ffff8880661cd900 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8c1b03a0 RDI: 0000000000000000
RBP: ffffffff82579705 R08: 0000000000000001 R09: 00000000000001c8
R10: 0000000000000200 R11: 0000000000000000 R12: ffff8880459a24c0
R13: ffffffff82579705 R14: 0000000000000287 R15: dffffc0000000000
FS: 00007f76039cd6c0(0000) GS:ffff888124345000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f76039cdd58 CR3: 00000000b0a6d000 CR4: 00000000003526f0
Call Trace:
<TASK>
__might_fault+0x10c/0x140 mm/memory.c:7218
_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:2522
recvmsg_copy_msghdr net/socket.c:2778 [inline]
___sys_recvmsg+0xdd/0x1a0 net/socket.c:2850
do_recvmmsg+0x301/0x760 net/socket.c:2949
__sys_recvmmsg net/socket.c:3023 [inline]
__do_sys_recvmmsg net/socket.c:3046 [inline]
__se_sys_recvmmsg net/socket.c:3039 [inline]
__x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3039
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f760579c799
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:00007f76039cd028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007f7605a16090 RCX: 00007f760579c799
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000007
RBP: 00007f7605832c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7605a16128 R14: 00007f7605a16090 R15: 00007fff594a1cb8
</TASK>