LXR linux/mm/Kconfig.debug

   1config 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
  10config 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
  34config 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
  42config 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
  56config 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
  67config 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
  80config 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
  92config 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.
  97