syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P34/1:b..l
	(detected by 0, t=10502 jiffies, g=150749, q=200 ncpus=2)
task:khugepaged      state:R  running task     stack:28424 pid:   34 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5182 [inline]
 __schedule+0xadf/0x52b0 kernel/sched/core.c:6494
 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6806
 irqentry_exit+0x31/0x80 kernel/entry/common.c:428
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:lock_acquire+0x1ef/0x570 kernel/locking/lockdep.c:5634
Code: cf a3 7e 83 f8 01 0f 85 e8 02 00 00 9c 58 f6 c4 02 0f 85 fb 02 00 00 48 83 7c 24 08 00 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 8b 84 24
RSP: 0018:ffffc90000cbf9e0 EFLAGS: 00000206
RAX: dffffc0000000000 RBX: 1ffff92000197f3e RCX: ffffffff815e53fe
RDX: 1ffff11002ec8976 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff908df977
R10: fffffbfff211bf2e R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888012860d38 R15: 0000000000000000
 start_flush_work kernel/workqueue.c:3048 [inline]
 __flush_work+0x4e5/0xb10 kernel/workqueue.c:3074
 __lru_add_drain_all+0x48d/0x7e0 mm/swap.c:875
 khugepaged_do_scan mm/khugepaged.c:2195 [inline]
 khugepaged+0x10f/0x4ad0 mm/khugepaged.c:2256
 kthread+0x2e4/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
rcu: rcu_preempt kthread starved for 9097 jiffies! g150749 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:28272 pid:   16 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5182 [inline]
 __schedule+0xadf/0x52b0 kernel/sched/core.c:6494
 schedule+0xda/0x1b0 kernel/sched/core.c:6570
 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1935
 rcu_gp_fqs_loop+0x190/0x910 kernel/rcu/tree.c:1657
 rcu_gp_kthread+0x236/0x360 kernel/rcu/tree.c:1854
 kthread+0x2e4/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.0.0-rc4-syzkaller-00204-g9b4509495418 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 nmi_cpu_backtrace.cold+0x46/0x14f lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x206/0x250 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:514
 print_other_cpu_stall kernel/rcu/tree_stall.h:619 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:762 [inline]
 rcu_pending kernel/rcu/tree.c:3660 [inline]
 rcu_sched_clock_irq+0x2404/0x2530 kernel/rcu/tree.c:2342
 update_process_times+0x11a/0x1a0 kernel/time/timer.c:1839
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:243
 tick_sched_timer+0xee/0x120 kernel/time/tick-sched.c:1480
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x1c0/0xe40 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1095 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1112
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1106
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:29 [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+0x6f/0xb0 drivers/acpi/processor_idle.c:113
Code: f7 84 db 74 06 5b e9 a0 a0 f8 f7 e8 9b a0 f8 f7 e8 f6 17 ff f7 66 90 e8 8f a0 f8 f7 0f 00 2d b8 12 d2 00 e8 83 a0 f8 f7 fb f4 <9c> 5b 81 e3 00 02 00 00 fa 31 ff 48 89 de e8 4e 9d f8 f7 48 85 db
RSP: 0018:ffffffff8bc07d38 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffffffff8bcbc980 RSI: ffffffff898298ad RDI: 0000000000000000
RBP: ffff8881457b8864 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000001
R13: 0000000000000001 R14: ffff8881457b8800 R15: ffff888146a93004
 acpi_idle_do_entry drivers/acpi/processor_idle.c:555 [inline]
 acpi_idle_enter+0x524/0x6a0 drivers/acpi/processor_idle.c:692
 cpuidle_enter_state+0x1ab/0xd30 drivers/cpuidle/cpuidle.c:239
 cpuidle_enter+0x4a/0xa0 drivers/cpuidle/cpuidle.c:356
 call_cpuidle kernel/sched/idle.c:155 [inline]
 cpuidle_idle_call kernel/sched/idle.c:236 [inline]
 do_idle+0x3e8/0x590 kernel/sched/idle.c:303
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:400
 rest_init+0x169/0x270 init/main.c:727
 arch_call_rest_init+0xf/0x14 init/main.c:883
 start_kernel+0x46e/0x48f init/main.c:1138
 secondary_startup_64_no_verify+0xce/0xdb
 </TASK>