syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4817/1:b..l
	(detected by 1, t=10502 jiffies, g=15221, q=350 ncpus=2)
task:syz.3.330       state:R  running task     stack:26456 pid:4817  ppid:3646   flags:0x00004000
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:653
RIP: 0010:lock_is_held_type+0x137/0x180
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c4 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc90004bbf8a8 EFLAGS: 00000206
RAX: b7d451d9fa951800 RBX: 0000000000000002 RCX: 0000000080000000
RDX: ffff8880273dd940 RSI: ffffffff8b0c13e0 RDI: ffffffff8b5d5de0
RBP: 0000000000000000 R08: ffffffff84250dbc R09: fffffbfff20e7245
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000246
R13: ffff8880273dd940 R14: 00000000ffffffff R15: ffffffff8d353858
 lock_is_held include/linux/lockdep.h:283 [inline]
 task_css include/linux/cgroup.h:509 [inline]
 blkcg_css+0xc8/0x1c0 block/blk-cgroup.c:77
 blk_cgroup_congested+0xb9/0x220 block/blk-cgroup.c:1998
 __cgroup_throttle_swaprate+0x6d/0x1b0 mm/swapfile.c:3671
 cgroup_throttle_swaprate include/linux/swap.h:662 [inline]
 do_anonymous_page mm/memory.c:4178 [inline]
 handle_pte_fault mm/memory.c:5011 [inline]
 __handle_mm_fault mm/memory.c:5155 [inline]
 handle_mm_fault+0x3b53/0x5340 mm/memory.c:5276
 faultin_page mm/gup.c:1009 [inline]
 __get_user_pages+0x4f3/0x1190 mm/gup.c:1233
 populate_vma_page_range+0x217/0x2b0 mm/gup.c:1590
 __mm_populate+0x275/0x440 mm/gup.c:1704
 mm_populate include/linux/mm.h:2797 [inline]
 __do_sys_mlockall mm/mlock.c:721 [inline]
 __se_sys_mlockall+0x32f/0x3c0 mm/mlock.c:697
 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: 0033:0x7fb7b67779f9
RSP: 002b:00007fb7b7639038 EFLAGS: 00000246 ORIG_RAX: 0000000000000097
RAX: ffffffffffffffda RBX: 00007fb7b6905f80 RCX: 00007fb7b67779f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 00007fb7b67e58ee R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb7b6905f80 R15: 00007fff8d7beee8
 </TASK>
rcu: rcu_preempt kthread starved for 9767 jiffies! g15221 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:27288 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 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567