syzbot

INFO: task syz.0.17:6043 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:25496 pid:6043  tgid:6043  ppid:5984   task_flags:0x400040 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5354 [inline]
 __schedule+0x165c/0x5520 kernel/sched/core.c:6966
 __schedule_loop kernel/sched/core.c:7049 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7064
 request_wait_answer fs/fuse/dev.c:590 [inline]
 __fuse_request_send fs/fuse/dev.c:604 [inline]
 __fuse_simple_request+0x12b7/0x1db0 fs/fuse/dev.c:699
 fuse_simple_request fs/fuse/fuse_i.h:1264 [inline]
 fuse_flush+0x66a/0x8a0 fs/fuse/file.c:500
 filp_flush+0xbd/0x190 fs/open.c:1467
 filp_close+0x1d/0x40 fs/open.c:1480
 __range_close fs/file.c:794 [inline]
 __do_sys_close_range fs/file.c:855 [inline]
 __se_sys_close_range+0x3d4/0x900 fs/file.c:819
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4bed39c819
RSP: 002b:00007fff5f3e9f38 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00007fff5f3ea020 RCX: 00007f4bed39c819
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00000000000401ee R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b31f20000 R11: 0000000000000246 R12: 00007fff5f3ea060
R13: 00007f4bed615fac R14: 0000000000040260 R15: 00007f4bed615fa0
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e95d260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8e95d260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8e95d260 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5593:
 #0: ffff8880371da0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0 drivers/tty/n_tty.c:2211

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 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+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xfd3/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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: 6249 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:cgroup_task_exit+0x0/0x130 kernel/cgroup/cgroup.c:7011
Code: 8c dd fd ff ff 48 c7 c7 c0 e7 31 90 e8 d9 e8 71 00 e9 cc fd ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <0f> 1f 40 d6 55 41 57 41 56 41 55 41 54 53 48 89 fb 49 bc 00 00 00
RSP: 0018:ffffc90003787af8 EFLAGS: 00000293
RAX: ffffffff816c8215 RBX: ffff88802dc65b80 RCX: ffff88802dc65b80
RDX: 0000000000000000 RSI: 0000000000080000 RDI: ffff88802dc65b80
RBP: ffffc90003787c30 R08: ffff88802dc65b87 R09: 1ffff11005b8cb70
R10: dffffc0000000000 R11: ffffed1005b8cb71 R12: dffffc0000000000
R13: 0000000000000009 R14: 0000000000000001 R15: 000000000000620d
FS:  0000000000000000(0000) GS:ffff88812525c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e7fc3b0a38 CR3: 000000000e74a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 do_exit+0x71f/0x22c0 kernel/exit.c:979
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1117
 get_signal+0x1284/0x1330 kernel/signal.c:3037
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:269 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd649357997
Code: Unable to access opcode bytes at 0x7fd64935796d.
RSP: 002b:00007ffdbb28d330 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: fffffffffffffe00 RBX: 0000555588c4c500 RCX: 00007fd649357997
RDX: 0000000040000000 RSI: 00007ffdbb28d38c RDI: ffffffffffffffff
RBP: 00007ffdbb28d38c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffdbb28d408
R13: 0000000000000002 R14: 00007ffdbb28d5e8 R15: 0000000000000000
 </TASK>