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authorStanislaw Gruszka <sgruszka@redhat.com>2012-01-11 03:07:28 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-11 04:30:42 +0400
commitc0a32fc5a2e470d0b02597b23ad79a317735253e (patch)
tree2d164edae0062918ca2088772c00b0615781353b /mm/Kconfig.debug
parent1399ff86f2a2bbacbbe68fa00c5f8c752b344723 (diff)
downloadlinux-c0a32fc5a2e470d0b02597b23ad79a317735253e.tar.xz
mm: more intensive memory corruption debugging
With CONFIG_DEBUG_PAGEALLOC configured, the CPU will generate an exception on access (read,write) to an unallocated page, which permits us to catch code which corrupts memory. However the kernel is trying to maximise memory usage, hence there are usually few free pages in the system and buggy code usually corrupts some crucial data. This patch changes the buddy allocator to keep more free/protected pages and to interlace free/protected and allocated pages to increase the probability of catching corruption. When the kernel is compiled with CONFIG_DEBUG_PAGEALLOC, debug_guardpage_minorder defines the minimum order used by the page allocator to grant a request. The requested size will be returned with the remaining pages used as guard pages. The default value of debug_guardpage_minorder is zero: no change from current behaviour. [akpm@linux-foundation.org: tweak documentation, s/flg/flag/] Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/Kconfig.debug')
-rw-r--r--mm/Kconfig.debug5
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 8b1a477162dc..4b2443254de2 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -4,6 +4,7 @@ config DEBUG_PAGEALLOC
depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
depends on !KMEMCHECK
select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
+ select PAGE_GUARD 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
@@ -22,3 +23,7 @@ config WANT_PAGE_DEBUG_FLAGS
config PAGE_POISONING
bool
select WANT_PAGE_DEBUG_FLAGS
+
+config PAGE_GUARD
+ bool
+ select WANT_PAGE_DEBUG_FLAGS