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* mm: more intensive memory corruption debuggingStanislaw Gruszka2012-01-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* mm: debug-pagealloc: fix kconfig dependency warningAkinobu Mita2011-03-22
| | | | | | | | | | | | | Fix kconfig dependency warning to satisfy dependencies: warning: (PAGE_POISONING) selects DEBUG_PAGEALLOC which has unmet direct dependencies (DEBUG_KERNEL && ARCH_SUPPORTS_DEBUG_PAGEALLOC && (!HIBERNATION || !PPC && !SPARC) && !KMEMCHECK) Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* trivial: improve help text for mm debug config optionsFrans Pop2009-09-21
| | | | | | | | | Improve the help text for PAGE_POISONING. Also fix some typos and improve consistency within the file. Signed-of-by: Frans Pop <elendil@planet.nl> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* kmemcheck: enable in the x86 KconfigVegard Nossum2009-06-15
| | | | | | | | | | let it rip! Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Ingo Molnar <mingo@elte.hu> [rebased for mainline inclusion] Signed-off-by: Vegard Nossum <vegardno@ifi.uio.no>
* generic debug pagealloc: build fixAkinobu Mita2009-04-02
| | | | | | | | | | | | | | | | | | | | | | | | | | This fixes a build failure with generic debug pagealloc: mm/debug-pagealloc.c: In function 'set_page_poison': mm/debug-pagealloc.c:8: error: 'struct page' has no member named 'debug_flags' mm/debug-pagealloc.c: In function 'clear_page_poison': mm/debug-pagealloc.c:13: error: 'struct page' has no member named 'debug_flags' mm/debug-pagealloc.c: In function 'page_poison': mm/debug-pagealloc.c:18: error: 'struct page' has no member named 'debug_flags' mm/debug-pagealloc.c: At top level: mm/debug-pagealloc.c:120: error: redefinition of 'kernel_map_pages' include/linux/mm.h:1278: error: previous definition of 'kernel_map_pages' was here mm/debug-pagealloc.c: In function 'kernel_map_pages': mm/debug-pagealloc.c:122: error: 'debug_pagealloc_enabled' undeclared (first use in this function) by fixing - debug_flags should be in struct page - define DEBUG_PAGEALLOC config option for all architectures Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Reported-by: Alexander Beregalov <a.beregalov@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* generic debug pageallocAkinobu Mita2009-04-01
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>