syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4373/1:b..l
	(detected by 0, t=10502 jiffies, g=9013, q=273 ncpus=2)
task:modprobe        state:R  running task     stack:22296 pid:4373  ppid:56     flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 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:691
RIP: 0010:mas_validate_child_slot lib/maple_tree.c:7083 [inline]
RIP: 0010:mt_validate+0x18a8/0x5ad0 lib/maple_tree.c:7248
Code: e0 16 84 8e 48 8b 74 24 50 e8 c4 05 c6 f9 eb 05 e8 1d f5 e0 f6 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 <84> c0 0f 85 09 05 00 00 41 0f b6 5d 00 4c 89 f7 48 89 de e8 d0 f6
RSP: 0018:ffffc90004747560 EFLAGS: 00000a06
RAX: 0000000000000004 RBX: ffff888077894e00 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffffc90004747750 R08: ffffffff8aa9a9d0 R09: ffffffff8aa9a6d5
R10: 0000000000000003 R11: ffff888077653b80 R12: 0000000000000003
R13: ffffffff8c2dca23 R14: 0000000000000002 R15: ffffc900047476b8
 validate_mm_mt+0x165/0x670 mm/mmap.c:294
 validate_mm+0x16e/0x380 mm/mmap.c:331
 __vma_adjust+0x1d41/0x1f40 mm/mmap.c:870
 __split_vma+0x36c/0x4c0
 mprotect_fixup+0x753/0x840 mm/mprotect.c:623
 do_mprotect_pkey+0x8b6/0xbe0 mm/mprotect.c:792
 __do_sys_mprotect mm/mprotect.c:819 [inline]
 __se_sys_mprotect mm/mprotect.c:816 [inline]
 __x64_sys_mprotect+0x7c/0x90 mm/mprotect.c:816
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc664907bb7
RSP: 002b:00007ffcdef02a08 EFLAGS: 00000206 ORIG_RAX: 000000000000000a
RAX: ffffffffffffffda RBX: 00007fc6648ea5c0 RCX: 00007fc664907bb7
RDX: 0000000000000001 RSI: 0000000000004000 RDI: 00007fc664814000
RBP: 00007ffcdef02b20 R08: 00007ffcdef00000 R09: 00007fc66491bab0
R10: 00007fc66467aab8 R11: 0000000000000206 R12: 00007fc6648ea5c0
R13: 00007fc66490feda R14: 00007fc664817bf8 R15: 00007fc664817b70
 </TASK>
rcu: rcu_preempt kthread starved for 10535 jiffies! g9013 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:25528 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 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:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567
sched: RT throttling activated