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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-06-10 05:30:17 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-06-10 05:30:17 -0300
commitd635711daa98be86d4c7fd01499c34f566b54ccb (patch)
treeaa5cc3760a27c3d57146498cb82fa549547de06c /mm/Kconfig.debug
parentc91265cd0efb83778f015b4d4b1129bd2cfd075e (diff)
Linux-libre 4.6.2-gnu
Diffstat (limited to 'mm/Kconfig.debug')
-rw-r--r--mm/Kconfig.debug68
1 files changed, 66 insertions, 2 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 957d3da53..22f4cd96a 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -16,8 +16,8 @@ config DEBUG_PAGEALLOC
select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
---help---
Unmap pages from the kernel linear mapping after free_pages().
- This results in a large slowdown, but helps to find certain types
- of memory corruption.
+ Depending on runtime enablement, this results in a small or large
+ slowdown, but helps to find certain types of memory corruption.
For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
fill the pages with poison patterns after free_pages() and verify
@@ -26,5 +26,69 @@ config DEBUG_PAGEALLOC
that would result in incorrect warnings of memory corruption after
a resume because free pages are not saved to the suspend image.
+ By default this option will have a small overhead, e.g. by not
+ allowing the kernel mapping to be backed by large pages on some
+ architectures. Even bigger overhead comes when the debugging is
+ enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
+ command line parameter.
+
+config DEBUG_PAGEALLOC_ENABLE_DEFAULT
+ bool "Enable debug page memory allocations by default?"
+ default n
+ depends on DEBUG_PAGEALLOC
+ ---help---
+ Enable debug page memory allocations by default? This value
+ can be overridden by debug_pagealloc=off|on.
+
config PAGE_POISONING
+ bool "Poison pages after freeing"
+ select PAGE_EXTENSION
+ select PAGE_POISONING_NO_SANITY if HIBERNATION
+ ---help---
+ Fill the pages with poison patterns after free_pages() and verify
+ the patterns before alloc_pages. The filling of the memory helps
+ reduce the risk of information leaks from freed data. This does
+ have a potential performance impact.
+
+ Note that "poison" here is not the same thing as the "HWPoison"
+ for CONFIG_MEMORY_FAILURE. This is software poisoning only.
+
+ If unsure, say N
+
+config PAGE_POISONING_NO_SANITY
+ depends on PAGE_POISONING
+ bool "Only poison, don't sanity check"
+ ---help---
+ Skip the sanity checking on alloc, only fill the pages with
+ poison on free. This reduces some of the overhead of the
+ poisoning feature.
+
+ If you are only interested in sanitization, say Y. Otherwise
+ say N.
+
+config PAGE_POISONING_ZERO
+ bool "Use zero for poisoning instead of random data"
+ depends on PAGE_POISONING
+ ---help---
+ Instead of using the existing poison value, fill the pages with
+ zeros. This makes it harder to detect when errors are occurring
+ due to sanitization but the zeroing at free means that it is
+ no longer necessary to write zeros when GFP_ZERO is used on
+ allocation.
+
+ Enabling page poisoning with this option will disable hibernation
+
+ If unsure, say N
bool
+
+config DEBUG_PAGE_REF
+ bool "Enable tracepoint to track down page reference manipulation"
+ depends on DEBUG_KERNEL
+ depends on TRACEPOINTS
+ ---help---
+ This is a feature to add tracepoint for tracking down page reference
+ manipulation. This tracking is useful to diagnose functional failure
+ due to migration failures caused by page reference mismatches. Be
+ careful when enabling this feature because it adds about 30 KB to the
+ kernel code. However the runtime performance overhead is virtually
+ nil until the tracepoints are actually enabled.