Enable statistic for Change Page Attribute

configname: CONFIG_X86_CPA_STATISTICS

Linux Kernel Configuration
└─>Processor type and features
└─>Enable statistic for Change Page Attribute
In linux kernel since version 4.2 (release Date: 2015-08-30)  
Expose statistics about the Change Page Attribute mechanism, which
helps to determine the effectiveness of preserving large and huge
page mappings when mapping protections are changed.

depends
CONFIG_DEBUG_FS