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- 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
- select PAGE_EXTENSION
- select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
- ---help---
- Unmap pages from the kernel linear mapping after free_pages().
- Depending on runtime enablement, this results in a small or 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.
- By default this option will have a small overhead, e.g. by not
- allowing the kernel mapping to be backed by large pages on some
- architectures. Even bigger overhead comes when the debugging is
- enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
- command line parameter.
- config DEBUG_PAGEALLOC_ENABLE_DEFAULT
- bool "Enable debug page memory allocations by default?"
- default n
- depends on DEBUG_PAGEALLOC
- ---help---
- Enable debug page memory allocations by default? This value
- can be overridden by debug_pagealloc=off|on.
- config PAGE_POISONING
- bool "Poison pages after freeing"
- select PAGE_POISONING_NO_SANITY if HIBERNATION
- ---help---
- Fill the pages with poison patterns after free_pages() and verify
- the patterns before alloc_pages. The filling of the memory helps
- reduce the risk of information leaks from freed data. This does
- have a potential performance impact if enabled with the
- "page_poison=1" kernel boot option.
- Note that "poison" here is not the same thing as the "HWPoison"
- for CONFIG_MEMORY_FAILURE. This is software poisoning only.
- If unsure, say N
- config PAGE_POISONING_NO_SANITY
- depends on PAGE_POISONING
- bool "Only poison, don't sanity check"
- ---help---
- Skip the sanity checking on alloc, only fill the pages with
- poison on free. This reduces some of the overhead of the
- poisoning feature.
- If you are only interested in sanitization, say Y. Otherwise
- say N.
- config PAGE_POISONING_ZERO
- bool "Use zero for poisoning instead of debugging value"
- depends on PAGE_POISONING
- ---help---
- Instead of using the existing poison value, fill the pages with
- zeros. This makes it harder to detect when errors are occurring
- due to sanitization but the zeroing at free means that it is
- no longer necessary to write zeros when GFP_ZERO is used on
- allocation.
- If unsure, say N
- config DEBUG_PAGE_REF
- bool "Enable tracepoint to track down page reference manipulation"
- depends on DEBUG_KERNEL
- depends on TRACEPOINTS
- ---help---
- This is a feature to add tracepoint for tracking down page reference
- manipulation. This tracking is useful to diagnose functional failure
- due to migration failures caused by page reference mismatches. Be
- careful when enabling this feature because it adds about 30 KB to the
- kernel code. However the runtime performance overhead is virtually
- nil until the tracepoints are actually enabled.
- config DEBUG_RODATA_TEST
- bool "Testcase for the marking rodata read-only"
- depends on STRICT_KERNEL_RWX
- ---help---
- This option enables a testcase for the setting rodata read-only.
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