config PAGE_EXTENSION	bool "Extend memmap on extra space for more information on page"	---help---	  Extend memmap on extra space for more information on page. This	  could be used for debugging features that need to insert extra	  field for every page. This extension enables us to save memory	  by not allocating this extra memory according to boottime	  configuration. config DEBUG_PAGEALLOC	bool "Debug page memory allocations"	depends on DEBUG_KERNEL	depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC	depends on !KMEMCHECK	select PAGE_EXTENSION	select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC	---help---	  Unmap pages from the kernel linear mapping after free_pages().	  This results in a large slowdown, but helps to find certain types	  of memory corruption. 	  For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,	  fill the pages with poison patterns after free_pages() and verify	  the patterns before alloc_pages().  Additionally,	  this option cannot be enabled in combination with hibernation as	  that would result in incorrect warnings of memory corruption after	  a resume because free pages are not saved to the suspend image. config PAGE_POISONING	bool