syzbot

INFO: task syz.1.892:9332 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.892       state:D stack:26312 pid:9332  tgid:9331  ppid:5839   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7026
 kvm_swap_active_memslots+0x2ea/0x7d0 virt/kvm/kvm_main.c:1642
 kvm_activate_memslot virt/kvm/kvm_main.c:1786 [inline]
 kvm_create_memslot virt/kvm/kvm_main.c:1852 [inline]
 kvm_set_memslot+0xd3b/0x1380 virt/kvm/kvm_main.c:1964
 kvm_set_memory_region+0xe53/0x1610 virt/kvm/kvm_main.c:2120
 kvm_set_internal_memslot+0x9f/0xe0 virt/kvm/kvm_main.c:2143
 __x86_set_memory_region+0x2f6/0x740 arch/x86/kvm/x86.c:13252
 kvm_alloc_apic_access_page+0xc5/0x140 arch/x86/kvm/lapic.c:2788
 vmx_vcpu_create+0x503/0xbd0 arch/x86/kvm/vmx/vmx.c:7607
 kvm_arch_vcpu_create+0x688/0xb20 arch/x86/kvm/x86.c:12705
 kvm_vm_ioctl_create_vcpu virt/kvm/kvm_main.c:4207 [inline]
 kvm_vm_ioctl+0xfec/0x3fd0 virt/kvm/kvm_main.c:5158
 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+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8ca918f6c9
RSP: 002b:00007f8ca73f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8ca93e5fa0 RCX: 00007f8ca918f6c9
RDX: 0000000000000000 RSI: 000000000000ae41 RDI: 0000000000000003
RBP: 00007f8ca9211f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8ca93e6038 R14: 00007f8ca93e5fa0 R15: 00007ffff5dfa3f8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by syz.1.892/9332:
 #0: ffff888078efc0a8 (&kvm->slots_lock){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:228 [inline]
 #0: ffff888078efc0a8 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_alloc_apic_access_page+0x27/0x140 arch/x86/kvm/lapic.c:2782
 #1: ffff888078efc138 (&kvm->slots_arch_lock){+.+.}-{4:4}, at: kvm_set_memslot+0x34/0x1380 virt/kvm/kvm_main.c:1915
2 locks held by getty/11688:
 #0: ffff88814d6460a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000972d2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222

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

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 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]
 check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
 watchdog+0xf3f/0x1170 kernel/hung_task.c:495
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>