mm/Kconfig.debug

   1 # SPDX-License-Identifier: GPL-2.0-only
   2 config PAGE_EXTENSION
   3         bool "Extend memmap on extra space for more information on page"
   4         ---help---
   5           Extend memmap on extra space for more information on page. This
   6           could be used for debugging features that need to insert extra
   7           field for every page. This extension enables us to save memory
   8           by not allocating this extra memory according to boottime
   9           configuration.
  10
  11 config DEBUG_PAGEALLOC
  12         bool "Debug page memory allocations"
  13         depends on DEBUG_KERNEL
  14         depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
  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           Also, the state of page tracking structures is checked more often as
  22           pages are being allocated and freed, as unexpected state changes
  23           often happen for same reasons as memory corruption (e.g. double free,
  24           use-after-free).
  25
  26           For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
  27           fill the pages with poison patterns after free_pages() and verify
  28           the patterns before alloc_pages(). Additionally, this option cannot
  29           be enabled in combination with hibernation as that would result in
  30           incorrect warnings of memory corruption after a resume because free
  31           pages are not saved to the suspend image.
  32
  33           By default this option will have a small overhead, e.g. by not
  34           allowing the kernel mapping to be backed by large pages on some
  35           architectures. Even bigger overhead comes when the debugging is
  36           enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
  37           command line parameter.
  38
  39 config DEBUG_PAGEALLOC_ENABLE_DEFAULT
  40         bool "Enable debug page memory allocations by default?"
  41         depends on DEBUG_PAGEALLOC
  42         ---help---
  43           Enable debug page memory allocations by default? This value
  44           can be overridden by debug_pagealloc=off|on.
  45
  46 config PAGE_OWNER
  47         bool "Track page owner"
  48         depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
  49         select DEBUG_FS
  50         select STACKTRACE
  51         select STACKDEPOT
  52         select PAGE_EXTENSION
  53         help
  54           This keeps track of what call chain is the owner of a page, may
  55           help to find bare alloc_page(s) leaks. Even if you include this
  56           feature on your build, it is disabled in default. You should pass
  57           "page_owner=on" to boot parameter in order to enable it. Eats
  58           a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
  59           for user-space helper.
  60
  61           If unsure, say N.
  62
  63 config PAGE_POISONING
  64         bool "Poison pages after freeing"
  65         select PAGE_POISONING_NO_SANITY if HIBERNATION
  66         ---help---
  67           Fill the pages with poison patterns after free_pages() and verify
  68           the patterns before alloc_pages. The filling of the memory helps
  69           reduce the risk of information leaks from freed data. This does
  70           have a potential performance impact if enabled with the
  71           "page_poison=1" kernel boot option.
  72
  73           Note that "poison" here is not the same thing as the "HWPoison"
  74           for CONFIG_MEMORY_FAILURE. This is software poisoning only.
  75
  76           If unsure, say N
  77
  78 config PAGE_POISONING_NO_SANITY
  79         depends on PAGE_POISONING
  80         bool "Only poison, don't sanity check"
  81         ---help---
  82            Skip the sanity checking on alloc, only fill the pages with
  83            poison on free. This reduces some of the overhead of the
  84            poisoning feature.
  85
  86            If you are only interested in sanitization, say Y. Otherwise
  87            say N.
  88
  89 config PAGE_POISONING_ZERO
  90         bool "Use zero for poisoning instead of debugging value"
  91         depends on PAGE_POISONING
  92         ---help---
  93            Instead of using the existing poison value, fill the pages with
  94            zeros. This makes it harder to detect when errors are occurring
  95            due to sanitization but the zeroing at free means that it is
  96            no longer necessary to write zeros when GFP_ZERO is used on
  97            allocation.
  98
  99            If unsure, say N
 100
 101 config DEBUG_PAGE_REF
 102         bool "Enable tracepoint to track down page reference manipulation"
 103         depends on DEBUG_KERNEL
 104         depends on TRACEPOINTS
 105         ---help---
 106           This is a feature to add tracepoint for tracking down page reference
 107           manipulation. This tracking is useful to diagnose functional failure
 108           due to migration failures caused by page reference mismatches.  Be
 109           careful when enabling this feature because it adds about 30 KB to the
 110           kernel code.  However the runtime performance overhead is virtually
 111           nil until the tracepoints are actually enabled.
 112
 113 config DEBUG_RODATA_TEST
 114     bool "Testcase for the marking rodata read-only"
 115     depends on STRICT_KERNEL_RWX
 116     ---help---
 117       This option enables a testcase for the setting rodata read-only.