syzbot

INFO: task syz.1.2480:15098 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.1.2480      state:D stack:28504 pid:15098 tgid:15088 ppid:5821   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x1139/0x6150 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6960
 futex_hash_allocate+0xd9e/0x10d0 kernel/futex/core.c:1829
 futex_hash_prctl+0x1cd/0x390 kernel/futex/core.c:1958
 __do_sys_prctl+0x1625/0x2220 kernel/sys.c:2869
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff2f818f749
RSP: 002b:00007ff2f90d0038 EFLAGS: 00000246 ORIG_RAX: 000000000000009d
RAX: ffffffffffffffda RBX: 00007ff2f83e6180 RCX: 00007ff2f818f749
RDX: 0000000000004000 RSI: 0000000000000001 RDI: 000000000000004e
RBP: 00007ff2f8213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff2f83e6218 R14: 00007ff2f83e6180 R15: 00007ffce69d05d8
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_exp_gp_kthr/18:
 #0: ffff8880b843ac98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:647 [inline]
 #0: ffff8880b843ac98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:632
1 lock held by khungtaskd/31:
 #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e3c96a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
3 locks held by kworker/1:3/978:
 #0: ffff88813ff51948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc90003d57c90 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffffffff8e3d4df8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a3/0x3c0 kernel/rcu/tree_exp.h:343
2 locks held by getty/5572:
 #0: ffff88814dc310a0 (&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+0x41b/0x1510 drivers/tty/n_tty.c:2211
1 lock held by syz-executor/5808:
1 lock held by syz-executor/5811:
 #0: ffffffff90141fa8 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff90141fa8 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x230 drivers/net/tun.c:3436
3 locks held by kworker/1:7/5924:
 #0: ffff88813ff51948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x128d/0x1b20 kernel/workqueue.c:3232
 #1: ffffc900046ffc90 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x914/0x1b20 kernel/workqueue.c:3233
 #2: ffff88802fb97240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1b8/0x65f0 drivers/net/netdevsim/fib.c:1490
1 lock held by syz-executor/11409:
1 lock held by syz-executor/17111:
 #0: ffffffff8e3d4df8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a3/0x3c0 kernel/rcu/tree_exp.h:343

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

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 10/25/2025
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]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x133/0x180 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xe66/0x1180 kernel/hung_task.c:515
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 17210 Comm: syz.2.2851 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:1089 [inline]
RIP: 0010:debug_check_no_obj_freed+0x2dd/0x600 lib/debugobjects.c:1129
Code: 00 00 ad de 49 89 56 08 48 89 c7 48 89 30 48 83 c6 22 48 89 70 08 e8 52 c0 ff ff 4c 89 f0 48 89 c2 48 c1 ea 03 42 80 3c 22 00 <0f> 84 23 ff ff ff 48 89 c7 48 89 44 24 10 e8 70 91 73 fd 48 8b 44
RSP: 0018:ffffc900036e7850 EFLAGS: 00000046
RAX: ffff888055dfb850 RBX: 0000000000000005 RCX: ffffffff819a448c
RDX: 1ffff1100abbf70a RSI: 0000000000000000 RDI: ffff888038a76910
RBP: ffffc900036e7980 R08: 0000000000000001 R09: fffff520006dcef8
R10: 0000000000000003 R11: ffff8880266c54b0 R12: dffffc0000000000
R13: ffffc9001723d000 R14: ffff888055dfb850 R15: ffffc9001763d000
FS:  0000000000000000(0000) GS:ffff8881249f5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f35fecd7e9c CR3: 000000007aa7b000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 000000000000f670 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 remove_vm_area+0x1ae/0x3f0 mm/vmalloc.c:3323
 vfree+0x90/0xb50 mm/vmalloc.c:3446
 kcov_put kernel/kcov.c:439 [inline]
 kcov_put kernel/kcov.c:435 [inline]
 kcov_close+0x34/0x60 kernel/kcov.c:535
 __fput+0x402/0xb70 fs/file_table.c:468
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x87f/0x2bd0 kernel/exit.c:971
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1112
 get_signal+0x2671/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7e0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x8c/0x540 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcd2a18f749
Code: Unable to access opcode bytes at 0x7fcd2a18f71f.
RSP: 002b:00007ffc6341c878 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffff92 RBX: 00000000000efd9e RCX: 00007fcd2a18f749
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fcd2a3e5fac
RBP: 0000000000000032 R08: 00007fcd2af29000 R09: 000000086341cb6f
R10: 00007ffc6341c970 R11: 0000000000000246 R12: 00007fcd2a3e5fac
R13: 00007ffc6341c970 R14: 00000000000efdd0 R15: 00007ffc6341c990
 </TASK>