syzbot

INFO: task syz.0.34:4464 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.34        state:D stack:26304 pid:4464  ppid:4391   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 perf_pending_task_sync kernel/events/core.c:5031 [inline]
 _free_event+0x171/0x10a0 kernel/events/core.c:5037
 put_event kernel/events/core.c:5162 [inline]
 perf_event_release_kernel+0x832/0x8c0 kernel/events/core.c:5287
 perf_release+0x37/0x40 kernel/events/core.c:5297
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1ca/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0x93e/0x2400 kernel/exit.c:880
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 __do_sys_exit_group kernel/exit.c:1033 [inline]
 __se_sys_exit_group kernel/exit.c:1031 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1031
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc83438eec9
RSP: 002b:00007ffcd63f0918 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc83438eec9
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffcd63f097c R08: 00000009d63f0a0f R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000011
R13: 00000000000927c0 R14: 000000000002c187 R15: 00007ffcd63f09d0
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u4:1/11:
 #0: ffff8880b8e3aad8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
 #1: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #1: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #1: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: do_perf_sw_event kernel/events/core.c:9706 [inline]
 #1: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: ___perf_sw_event+0x13c/0x630 kernel/events/core.c:9744
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2b570 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2bd90 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2abe0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
1 lock held by klogd/3626:
 #0: ffff8880b8e3aad8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
2 locks held by getty/4026:
 #0: ffff88814ce7f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xeee/0xf30 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3626 Comm: klogd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:check_preemption_disabled+0x0/0x110 lib/smp_processor_id.c:13
Code: c7 20 74 bc 8c 4c 89 f6 e8 fd f8 16 fa e9 6e ff ff ff 00 00 cc cc 00 00 cc cc 48 c7 c7 c0 fc de 8a 48 c7 c6 00 fd de 8a eb 00 <55> 41 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44
RSP: 0018:ffffc90003287a18 EFLAGS: 00000082
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff81630a00
RDX: 0000000000000000 RSI: ffffffff8a8c1680 RDI: ffffffff8adefd20
RBP: ffffc90003287b40 R08: dffffc0000000000 R09: fffffbfff215c44f
R10: fffffbfff215c44f R11: 1ffffffff215c44e R12: 0000000000000000
R13: 1ffff92000650f50 R14: 0000000000000246 R15: dffffc0000000000
FS:  00007f0ef6389c80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055587b629168 CR3: 000000007e5a8000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 lockdep_recursion_finish kernel/locking/lockdep.c:467 [inline]
 lock_acquire+0x1c4/0x490 kernel/locking/lockdep.c:5664
 __might_fault+0xc2/0x120 mm/memory.c:5852
 _copy_to_user+0x27/0x130 lib/usercopy.c:36
 copy_to_user include/linux/uaccess.h:169 [inline]
 syslog_print+0x456/0x590 kernel/printk/printk.c:1577
 do_syslog+0x7bd/0x8b0 kernel/printk/printk.c:1679
 __do_sys_syslog kernel/printk/printk.c:1771 [inline]
 __se_sys_syslog kernel/printk/printk.c:1769 [inline]
 __x64_sys_syslog+0x78/0x90 kernel/printk/printk.c:1769
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f0ef6553a37
Code: 73 01 c3 48 8b 0d c1 f3 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 67 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 91 f3 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffcdc152fb8 EFLAGS: 00000206 ORIG_RAX: 0000000000000067
RAX: ffffffffffffffda RBX: 00007f0ef66f3490 RCX: 00007f0ef6553a37
RDX: 00000000000003ff RSI: 00007f0ef66f3490 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000206 R12: 00007f0ef66f3490
R13: 00007f0ef66d0dfe R14: 00007f0ef66f3885 R15: 00007f0ef66f3885
 </TASK>