syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5870/1:b..l
	(detected by 0, t=10502 jiffies, g=31553, q=326 ncpus=2)
task:syz-executor.4  state:R  running task     stack:21304 pid:5870  ppid:1      flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x142d/0x4550 kernel/sched/core.c:6558
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870
 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:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:122 [inline]
RIP: 0010:lock_acquire+0x136/0x5a0 kernel/locking/lockdep.c:5638
Code: 03 42 0f b6 04 28 84 c0 0f 85 dd 02 00 00 83 3d 03 5c 09 0d 00 0f 84 3f 01 00 00 65 8b 05 92 16 98 7e 85 c0 0f 85 88 01 00 00 <65> 48 8b 1d 02 0d 98 7e 48 81 c3 dc 0a 00 00 48 89 d8 48 c1 e8 03
RSP: 0018:ffffc9000321f480 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff816a61eb
RDX: 0000000000000000 RSI: ffffffff8b3d45c0 RDI: ffffffff8b3d4580
RBP: ffffc9000321f5d0 R08: dffffc0000000000 R09: fffffbfff1ce712e
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000643e98
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea0001799a88
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 page_ext_get+0x39/0x2a0 mm/page_ext.c:157
 __page_table_check_zero+0x139/0x4a0 mm/page_table_check.c:140
 page_table_check_free include/linux/page_table_check.h:46 [inline]
 free_pages_prepare mm/page_alloc.c:1441 [inline]
 free_pcp_prepare mm/page_alloc.c:1490 [inline]
 free_unref_page_prepare+0xf73/0x1120 mm/page_alloc.c:3358
 free_unref_page+0x33/0x3e0 mm/page_alloc.c:3453
 __vunmap+0x834/0x9a0 mm/vmalloc.c:2717
 kcov_put kernel/kcov.c:428 [inline]
 kcov_close+0x27/0x50 kernel/kcov.c:524
 __fput+0x3b7/0x890 fs/file_table.c:320
 task_work_run+0x246/0x300 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa73/0x26a0 kernel/exit.c:869
 do_group_exit+0x202/0x2b0 kernel/exit.c:1019
 get_signal+0x16f7/0x17d0 kernel/signal.c:2862
 arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8a19a7ec3a
RSP: 002b:00007ffc22bcb2a8 EFLAGS: 00000206 ORIG_RAX: 0000000000000036
RAX: 0000000000000000 RBX: 00007ffc22bcb330 RCX: 00007f8a19a7ec3a
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000558 R09: 0079746972756365
R10: 00007f8a19b83920 R11: 0000000000000206 R12: 00007f8a19b838c0
R13: 00007ffc22bcb2cc R14: 0000000000000000 R15: 00007f8a19b84d00
 </TASK>
rcu: rcu_preempt kthread starved for 9564 jiffies! g31553 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:26680 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x142d/0x4550 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 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:308
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.92-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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:113 [inline]
RIP: 0010:acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:572
Code: 4f f5 f6 48 83 e3 08 0f 85 0b 01 00 00 4c 8d 74 24 20 e8 d4 0d fc f6 0f 1f 44 00 00 e8 7a 4b f5 f6 0f 00 2d 03 1f b2 00 fb f4 <4c> 89 f3 48 c1 eb 03 42 80 3c 3b 00 74 08 4c 89 f7 e8 5b cb 4c f7
RSP: 0018:ffffffff8ce07b20 EFLAGS: 000002d3
RAX: ffffffff8a9541d6 RBX: 0000000000000000 RCX: ffffffff8cebd800
RDX: 0000000000000000 RSI: ffffffff8aec01c0 RDI: ffffffff8b3d45e0
RBP: ffffffff8ce07bb0 R08: ffffffff8a9541b8 R09: fffffbfff19d7b01
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffffffff19c0f64
R13: ffff88801632c804 R14: ffffffff8ce07b40 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0011bf000 CR3: 00000000216b6000 CR4: 00000000003526f0
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:709
 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:734
 arch_call_rest_init+0xa/0xa init/main.c:894
 start_kernel+0x496/0x53f init/main.c:1141
 secondary_startup_64_no_verify+0xcf/0xdb
 </TASK>