From: Andi Kleen Impact: optional, useful for debugging Add a new madvice sub command to inject poison for some pages in a process' address space. This is useful for testing the poison page handling. Open issues: - This patch allows root to tie up arbitary amounts of memory. Should this be disabled inside containers? - There's a small race window between getting the page and injecting. The patch drops the ref count because otherwise memory_failure complains about dangling references. In theory with a multi threaded injector one could inject poison for a process foreign page this way. Not a serious issue right now. v2: Use write flag for get_user_pages to make sure to always get a fresh page v3: Don't request write mapping (Fengguang Wu) Reviewed-by: Wu Fengguang Signed-off-by: Andi Kleen --- include/asm-generic/mman-common.h | 1 mm/madvise.c | 36 ++++++++++++++++++++++++++++ 2 files changed, 37 insertions(+) --- sound-2.6.orig/mm/madvise.c +++ sound-2.6/mm/madvise.c @@ -207,6 +207,38 @@ static long madvise_remove(struct vm_are return error; } +#ifdef CONFIG_MEMORY_FAILURE +/* + * Error injection support for memory error handling. + */ +static int madvise_hwpoison(unsigned long start, unsigned long end) +{ + /* + * RED-PEN + * This allows to tie up arbitary amounts of memory. + * Might be a good idea to disable it inside containers even for root. + */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + for (; start < end; start += PAGE_SIZE) { + struct page *p; + int ret = get_user_pages(current, current->mm, start, 1, + 0, 0, &p, NULL); + if (ret != 1) + return ret; + put_page(p); + /* + * RED-PEN page can be reused in a short window, but otherwise + * we'll have to fight with the reference count. + */ + printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n", + page_to_pfn(p), start); + memory_failure(page_to_pfn(p), 0); + } + return 0; +} +#endif + static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, unsigned long start, unsigned long end, int behavior) @@ -307,6 +339,10 @@ SYSCALL_DEFINE3(madvise, unsigned long, int write; size_t len; +#ifdef CONFIG_MEMORY_FAILURE + if (behavior == MADV_HWPOISON) + return madvise_hwpoison(start, start+len_in); +#endif if (!madvise_behavior_valid(behavior)) return error; --- sound-2.6.orig/include/asm-generic/mman-common.h +++ sound-2.6/include/asm-generic/mman-common.h @@ -34,6 +34,7 @@ #define MADV_REMOVE 9 /* remove these pages & resources */ #define MADV_DONTFORK 10 /* don't inherit across fork */ #define MADV_DOFORK 11 /* do inherit across fork */ +#define MADV_HWPOISON 12 /* poison a page for testing */ /* compatibility flags */ #define MAP_FILE 0 -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/