diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig.debug | 17 | ||||
| -rw-r--r-- | mm/Makefile | 1 | ||||
| -rw-r--r-- | mm/debug-pagealloc.c | 129 |
3 files changed, 147 insertions, 0 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug new file mode 100644 index 00000000000..c8d62d49a44 --- /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. diff --git a/mm/Makefile b/mm/Makefile index 818569b68f4..ec73c68b601 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -24,6 +24,7 @@ obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o obj-$(CONFIG_TMPFS_POSIX_ACL) += shmem_acl.o obj-$(CONFIG_SLOB) += slob.o obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o +obj-$(CONFIG_PAGE_POISONING) += debug-pagealloc.o obj-$(CONFIG_SLAB) += slab.o obj-$(CONFIG_SLUB) += slub.o obj-$(CONFIG_FAILSLAB) += failslab.o diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c new file mode 100644 index 00000000000..a1e3324de2b --- /dev/null +++ b/mm/debug-pagealloc.c @@ -0,0 +1,129 @@ +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/page-debug-flags.h> +#include <linux/poison.h> + +static inline void set_page_poison(struct page *page) +{ + __set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags); +} + +static inline void clear_page_poison(struct page *page) +{ + __clear_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags); +} + +static inline bool page_poison(struct page *page) +{ + return test_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags); +} + +static void poison_highpage(struct page *page) +{ + /* + * Page poisoning for highmem pages is not implemented. + * + * This can be called from interrupt contexts. + * So we need to create a new kmap_atomic slot for this + * application and it will need interrupt protection. + */ +} + +static void poison_page(struct page *page) +{ + void *addr; + + if (PageHighMem(page)) { + poison_highpage(page); + return; + } + set_page_poison(page); + addr = page_address(page); + memset(addr, PAGE_POISON, PAGE_SIZE); +} + +static void poison_pages(struct page *page, int n) +{ + int i; + + for (i = 0; i < n; i++) + poison_page(page + i); +} + +static bool single_bit_flip(unsigned char a, unsigned char b) +{ + unsigned char error = a ^ b; + + return error && !(error & (error - 1)); +} + +static void check_poison_mem(unsigned char *mem, size_t bytes) +{ + unsigned char *start; + unsigned char *end; + + for (start = mem; start < mem + bytes; start++) { + if (*start != PAGE_POISON) + break; + } + if (start == mem + bytes) + return; + + for (end = mem + bytes - 1; end > start; end--) { + if (*end != PAGE_POISON) + break; + } + + if (!printk_ratelimit()) + return; + else if (start == end && single_bit_flip(*start, PAGE_POISON)) + printk(KERN_ERR "pagealloc: single bit error\n"); + else + printk(KERN_ERR "pagealloc: memory corruption\n"); + + print_hex_dump(KERN_ERR, "", DUMP_PREFIX_ADDRESS, 16, 1, start, + end - start + 1, 1); + dump_stack(); +} + +static void unpoison_highpage(struct page *page) +{ + /* + * See comment in poison_highpage(). + * Highmem pages should not be poisoned for now + */ + BUG_ON(page_poison(page)); +} + +static void unpoison_page(struct page *page) +{ + if (PageHighMem(page)) { + unpoison_highpage(page); + return; + } + if (page_poison(page)) { + void *addr = page_address(page); + + check_poison_mem(addr, PAGE_SIZE); + clear_page_poison(page); + } +} + +static void unpoison_pages(struct page *page, int n) +{ + int i; + + for (i = 0; i < n; i++) + unpoison_page(page + i); +} + +void kernel_map_pages(struct page *page, int numpages, int enable) +{ + if (!debug_pagealloc_enabled) + return; + + if (enable) + unpoison_pages(page, numpages); + else + poison_pages(page, numpages); +} |