mm/Kconfig.debug

   1 config PAGE_EXTENSION
   2         bool "Extend memmap on extra space for more information on page"
   3         ---help---
   4           Extend memmap on extra space for more information on page. This
   5           could be used for debugging features that need to insert extra
   6           field for every page. This extension enables us to save memory
   7           by not allocating this extra memory according to boottime
   8           configuration.
   9
  10 config DEBUG_PAGEALLOC
  11         bool "Debug page memory allocations"
  12         depends on DEBUG_KERNEL
  13         depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
  14         depends on !KMEMCHECK
  15         select PAGE_EXTENSION
  16         select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
  17         ---help---
  18           Unmap pages from the kernel linear mapping after free_pages().
  19           Depending on runtime enablement, this results in a small or large
  20           slowdown, but helps to find certain types of memory corruption.
  21
  22           For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
  23           fill the pages with poison patterns after free_pages() and verify
  24           the patterns before alloc_pages().  Additionally,
  25           this option cannot be enabled in combination with hibernation as
  26           that would result in incorrect warnings of memory corruption after
  27           a resume because free pages are not saved to the suspend image.
  28
  29           By default this option will have a small overhead, e.g. by not
  30           allowing the kernel mapping to be backed by large pages on some
  31           architectures. Even bigger overhead comes when the debugging is
  32           enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
  33           command line parameter.
  34
  35 config DEBUG_PAGEALLOC_ENABLE_DEFAULT
  36         bool "Enable debug page memory allocations by default?"
  37         default n
  38         depends on DEBUG_PAGEALLOC
  39         ---help---
  40           Enable debug page memory allocations by default? This value
  41           can be overridden by debug_pagealloc=off|on.
  42
  43 config PAGE_POISONING
  44         bool "Poison pages after freeing"
  45         select PAGE_POISONING_NO_SANITY if HIBERNATION
  46         ---help---
  47           Fill the pages with poison patterns after free_pages() and verify
  48           the patterns before alloc_pages. The filling of the memory helps
  49           reduce the risk of information leaks from freed data. This does
  50           have a potential performance impact.
  51
  52           Note that "poison" here is not the same thing as the "HWPoison"
  53           for CONFIG_MEMORY_FAILURE. This is software poisoning only.
  54
  55           If unsure, say N
  56
  57 config PAGE_POISONING_NO_SANITY
  58         depends on PAGE_POISONING
  59         bool "Only poison, don't sanity check"
  60         ---help---
  61            Skip the sanity checking on alloc, only fill the pages with
  62            poison on free. This reduces some of the overhead of the
  63            poisoning feature.
  64
  65            If you are only interested in sanitization, say Y. Otherwise
  66            say N.
  67
  68 config PAGE_POISONING_ZERO
  69         bool "Use zero for poisoning instead of random data"
  70         depends on PAGE_POISONING
  71         ---help---
  72            Instead of using the existing poison value, fill the pages with
  73            zeros. This makes it harder to detect when errors are occurring
  74            due to sanitization but the zeroing at free means that it is
  75            no longer necessary to write zeros when GFP_ZERO is used on
  76            allocation.
  77
  78            If unsure, say N
  79         bool
  80
  81 config DEBUG_PAGE_REF
  82         bool "Enable tracepoint to track down page reference manipulation"
  83         depends on DEBUG_KERNEL
  84         depends on TRACEPOINTS
  85         ---help---
  86           This is a feature to add tracepoint for tracking down page reference
  87           manipulation. This tracking is useful to diagnose functional failure
  88           due to migration failures caused by page reference mismatches.  Be
  89           careful when enabling this feature because it adds about 30 KB to the
  90           kernel code.  However the runtime performance overhead is virtually
  91           nil until the tracepoints are actually enabled.
  92
  93 config DEBUG_RODATA_TEST
  94     bool "Testcase for the marking rodata read-only"
  95     depends on STRICT_KERNEL_RWX
  96     ---help---
  97       This option enables a testcase for the setting rodata read-only.