generic debug pagealloc
CONFIG_DEBUG_PAGEALLOC is now supported by x86, powerpc, sparc64, and
s390. This patch implements it for the rest of the architectures by
filling the pages with poison byte patterns after free_pages() and
verifying the poison patterns before alloc_pages().
This generic one cannot detect invalid page accesses immediately but
invalid read access may cause invalid dereference by poisoned memory and
invalid write access can be detected after a long delay.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
new file mode 100644
index 0000000..c8d62d4
--- /dev/null
+++ b/mm/Kconfig.debug
@@ -0,0 +1,17 @@
+config WANT_PAGE_DEBUG_FLAGS
+ bool
+
+config PAGE_POISONING
+ bool "Debug page memory allocations"
+ depends on DEBUG_KERNEL && !ARCH_SUPPORTS_DEBUG_PAGEALLOC
+ depends on !HIBERNATION
+ select DEBUG_PAGEALLOC
+ select WANT_PAGE_DEBUG_FLAGS
+ help
+ Fill the pages with poison patterns after free_pages() and verify
+ the patterns before alloc_pages(). This results in a large slowdown,
+ but helps to find certain types of memory corruptions.
+
+ This option cannot enalbe with hibernation. Otherwise, it will get
+ wrong messages for memory corruption because the free pages are not
+ saved to the suspend image.