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