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>

1 files changed, 17 insertions, 0 deletions

diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
new file mode 100644
index 000000000000..c8d62d49a44e
--- /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.