rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P42/1:b..l..
rcu: 	(detected by 1, t=10503 jiffies, g=153657, q=858651 ncpus=2)
task:khugepaged      state:R  running task     stack:26536 pid:42    tgid:42    ppid:2      task_flags:0x200040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5584 [inline]
 __schedule+0x18a6/0x5c10 kernel/sched/core.c:7386
 preempt_schedule_irq+0x4b/0x90 kernel/sched/core.c:7666
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:543 [inline]
 irqentry_exit+0x14f/0x9b0 kernel/entry/common.c:154
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:clear_pages arch/x86/include/asm/page_64.h:103 [inline]
RIP: 0010:clear_page arch/x86/include/asm/page_64.h:114 [inline]
RIP: 0010:clear_user_page include/linux/highmem.h:217 [inline]
RIP: 0010:clear_user_highpage include/linux/highmem.h:265 [inline]
RIP: 0010:__collapse_huge_page_copy+0x1f0/0xc70 mm/khugepaged.c:875
Code: 24 08 42 80 3c 28 00 74 0c 48 c7 c7 00 bf 97 8e e8 25 dc f8 ff 48 c1 e3 06 48 03 1d 0a 0d 4f 0c b9 00 10 00 00 31 c0 48 89 df <f3> aa 0f 1f 44 00 00 e9 bc 00 00 00 e8 3f 96 80 ff 48 b8 ff ff ff
RSP: 0018:ffffc90000b27408 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88809319d000 RCX: 00000000000004c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88809319db40
RBP: ffffea00024c0000 R08: ffff888048efdfff R09: 1ffff110091dfbff
R10: dffffc0000000000 R11: ffffed10091dfc00 R12: 000000000000019e
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000009
 collapse_huge_page mm/khugepaged.c:1399 [inline]
 collapse_anon mm/khugepaged.c:1514 [inline]
 collapse_pmd+0x1c9d/0x6870 mm/khugepaged.c:2853
 collapse_single_pmd+0x1c74/0x36b0 mm/khugepaged.c:2914
 collapse_scan_mm_slot mm/khugepaged.c:2989 [inline]
 khugepaged_do_scan mm/khugepaged.c:3073 [inline]
 khugepaged+0xacd/0x1890 mm/khugepaged.c:3128
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>