syzbot

INFO: task syz.2.1731:14343 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.2.1731      state:D stack:24816 pid:14343 tgid:14341 ppid:5836   task_flags:0x400140 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
 kvm_swap_active_memslots+0x2ea/0x7d0 virt/kvm/kvm_main.c:1643
 kvm_activate_memslot virt/kvm/kvm_main.c:1802 [inline]
 kvm_create_memslot virt/kvm/kvm_main.c:1868 [inline]
 kvm_set_memslot+0xd70/0x15c0 virt/kvm/kvm_main.c:1980
 kvm_set_memory_region+0xe4a/0x15e0 virt/kvm/kvm_main.c:2136
 kvm_set_internal_memslot+0x9f/0xe0 virt/kvm/kvm_main.c:2159
 __x86_set_memory_region+0x2f6/0x740 arch/x86/kvm/x86.c:13285
 kvm_alloc_apic_access_page+0xc5/0x140 arch/x86/kvm/lapic.c:2806
 vmx_vcpu_create+0x503/0xbd0 arch/x86/kvm/vmx/vmx.c:7637
 kvm_arch_vcpu_create+0x688/0xb20 arch/x86/kvm/x86.c:12733
 kvm_vm_ioctl_create_vcpu virt/kvm/kvm_main.c:4223 [inline]
 kvm_vm_ioctl+0x105e/0x4090 virt/kvm/kvm_main.c:5180
 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/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3cb7b8f7c9
RSP: 002b:00007f3cb8a38038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3cb7de5fa0 RCX: 00007f3cb7b8f7c9
RDX: 0000000000000000 RSI: 000000000000ae41 RDI: 0000000000000003
RBP: 00007f3cb7c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3cb7de6038 R14: 00007f3cb7de5fa0 R15: 00007fffedf2f3b8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3c9520 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c9520 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e3c9520 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by getty/11596:
 #0: ffff8880315820a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90004edb2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x1510 drivers/tty/n_tty.c:2211
2 locks held by syz.2.1731/14343:
 #0: ffff888022f400a8 (&kvm->slots_lock){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #0: ffff888022f400a8 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_alloc_apic_access_page+0x27/0x140 arch/x86/kvm/lapic.c:2800
 #1: ffff888022f40138 (&kvm->slots_arch_lock){+.+.}-{4:4}, at: kvm_set_memslot+0x34/0x15c0 virt/kvm/kvm_main.c:1931
2 locks held by syz.3.2374/17298:

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

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>