blob: 22f4cd96acb0d3a320c9a6440d63585f0dfd6057 [file] [log] [blame]
Joonsoo Kimeefa8642014-12-12 16:55:46 -08001config 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
Akinobu Mitaee3b4292009-04-02 16:56:30 -070010config DEBUG_PAGEALLOC
11 bool "Debug page memory allocations"
Akinobu Mita7bc32f62011-03-22 16:32:46 -070012 depends on DEBUG_KERNEL
13 depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
Vegard Nossum7d46d9e2008-04-04 00:51:41 +020014 depends on !KMEMCHECK
Joonsoo Kime30825f2014-12-12 16:55:49 -080015 select PAGE_EXTENSION
Akinobu Mita7bc32f62011-03-22 16:32:46 -070016 select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
Akinobu Mitaee3b4292009-04-02 16:56:30 -070017 ---help---
18 Unmap pages from the kernel linear mapping after free_pages().
Christian Borntraegerea6eabb2016-03-15 14:55:30 -070019 Depending on runtime enablement, this results in a small or large
20 slowdown, but helps to find certain types of memory corruption.
Akinobu Mitaee3b4292009-04-02 16:56:30 -070021
Akinobu Mita7bc32f62011-03-22 16:32:46 -070022 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
Christian Borntraegerea6eabb2016-03-15 14:55:30 -070029 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
35config 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
Akinobu Mita6a11f752009-03-31 15:23:17 -070043config PAGE_POISONING
Laura Abbott8823b1d2016-03-15 14:56:27 -070044 bool "Poison pages after freeing"
45 select PAGE_EXTENSION
46 select PAGE_POISONING_NO_SANITY if HIBERNATION
47 ---help---
48 Fill the pages with poison patterns after free_pages() and verify
49 the patterns before alloc_pages. The filling of the memory helps
50 reduce the risk of information leaks from freed data. This does
51 have a potential performance impact.
52
53 Note that "poison" here is not the same thing as the "HWPoison"
54 for CONFIG_MEMORY_FAILURE. This is software poisoning only.
55
56 If unsure, say N
57
58config PAGE_POISONING_NO_SANITY
59 depends on PAGE_POISONING
60 bool "Only poison, don't sanity check"
61 ---help---
62 Skip the sanity checking on alloc, only fill the pages with
63 poison on free. This reduces some of the overhead of the
64 poisoning feature.
65
66 If you are only interested in sanitization, say Y. Otherwise
67 say N.
Laura Abbott1414c7f2016-03-15 14:56:30 -070068
69config PAGE_POISONING_ZERO
70 bool "Use zero for poisoning instead of random data"
71 depends on PAGE_POISONING
72 ---help---
73 Instead of using the existing poison value, fill the pages with
74 zeros. This makes it harder to detect when errors are occurring
75 due to sanitization but the zeroing at free means that it is
76 no longer necessary to write zeros when GFP_ZERO is used on
77 allocation.
78
79 Enabling page poisoning with this option will disable hibernation
80
81 If unsure, say N
Joonsoo Kim95813b82016-03-17 14:19:29 -070082 bool
83
84config DEBUG_PAGE_REF
85 bool "Enable tracepoint to track down page reference manipulation"
86 depends on DEBUG_KERNEL
87 depends on TRACEPOINTS
88 ---help---
89 This is a feature to add tracepoint for tracking down page reference
90 manipulation. This tracking is useful to diagnose functional failure
91 due to migration failures caused by page reference mismatches. Be
92 careful when enabling this feature because it adds about 30 KB to the
93 kernel code. However the runtime performance overhead is virtually
94 nil until the tracepoints are actually enabled.