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-rw-r--r--mm/Kconfig.debug18
1 files changed, 16 insertions, 2 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 957d3da53ddd..a0c136af9c91 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 +26,19 @@ 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