syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5970/1:b..l
	(detected by 0, t=10502 jiffies, g=23505, q=12 ncpus=2)
task:vhost-5968      state:R  running task     stack:26584 pid:5970  ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6873
 irqentry_exit+0x53/0x80 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:653
RIP: 0010:lock_acquire+0x26f/0x5a0 kernel/locking/lockdep.c:5666
Code: 2b 00 74 08 4c 89 f7 e8 cf b2 77 00 f6 44 24 61 02 0f 85 84 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc90003497320 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92000692e70 RCX: 1ffff92000692e10
RDX: dffffc0000000000 RSI: ffffffff8aec13c0 RDI: ffffffff8b3d48a0
RBP: ffffc90003497468 R08: dffffc0000000000 R09: fffffbfff2093845
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000692e6c
R13: dffffc0000000000 R14: ffffc90003497380 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 mtree_load+0x219/0xdf0 lib/maple_tree.c:6249
 vma_lookup include/linux/mm.h:2865 [inline]
 __get_user_pages+0x317/0x1190 mm/gup.c:1185
 __get_user_pages_locked mm/gup.c:1437 [inline]
 get_user_pages_unlocked+0x23b/0x8a0 mm/gup.c:2346
 __gup_longterm_unlocked mm/gup.c:2957 [inline]
 internal_get_user_pages_fast+0x2832/0x2cf0 mm/gup.c:3047
 set_bit_to_user drivers/vhost/vhost.c:1850 [inline]
 log_write+0xda/0x390 drivers/vhost/vhost.c:1876
 vhost_update_used_flags+0x1e9/0x2b0 drivers/vhost/vhost.c:1995
 vhost_enable_notify+0xb2/0x800 drivers/vhost/vhost.c:2552
 vhost_vsock_handle_tx_kick+0x2cb/0xe10 drivers/vhost/vsock.c:500
 vhost_worker+0x1f8/0x360 drivers/vhost/vhost.c:364
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: rcu_preempt kthread starved for 10533 jiffies! g23505 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:26752 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 schedule+0xbf/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.100-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:22 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:130 [inline]
RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
RIP: 0010:acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567
Code: 0b f5 f6 48 83 e3 08 0f 85 0b 01 00 00 4c 8d 74 24 20 e8 f4 c9 fb f6 0f 1f 44 00 00 e8 4a 07 f5 f6 0f 00 2d 63 d5 b1 00 fb f4 <4c> 89 f3 48 c1 eb 03 42 80 3c 3b 00 74 08 4c 89 f7 e8 3b 8f 4c f7
RSP: 0018:ffffffff8ce07b20 EFLAGS: 000002d3
RAX: ffffffff8a959336 RBX: 0000000000000000 RCX: ffffffff8cebd800
RDX: 0000000000000000 RSI: ffffffff8aec0240 RDI: ffffffff8b3d48a0
RBP: ffffffff8ce07bb0 R08: ffffffff8a959318 R09: fffffbfff19d7b01
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffffffff19c0f64
R13: ffff888017333804 R14: ffffffff8ce07b40 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555556712808 CR3: 0000000060914000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 </IRQ>
 <TASK>
 acpi_idle_enter+0x352/0x4f0 drivers/acpi/processor_idle.c:704
 cpuidle_enter_state+0x516/0xf80 drivers/cpuidle/cpuidle.c:239
 cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:356
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:236 [inline]
 do_idle+0x3ce/0x680 kernel/sched/idle.c:303
 cpu_startup_entry+0x3d/0x60 kernel/sched/idle.c:401
 rest_init+0x2da/0x300 init/main.c:733
 arch_call_rest_init+0xa/0xa init/main.c:893
 start_kernel+0x496/0x53f init/main.c:1140
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>