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