On Tue, Jan 26, 2016 at 12:55 AM, Laura Abbott
<labbott@xxxxxxxxxxxxxxxxx> wrote:
> --- a/mm/debug-pagealloc.c
> +++ b/mm/debug-pagealloc.c
> @@ -8,11 +8,5 @@
>
> void __kernel_map_pages(struct page *page, int numpages, int enable)
> {
> - if (!page_poisoning_enabled())
> - return;
> -
> - if (enable)
> - unpoison_pages(page, numpages);
> - else
> - poison_pages(page, numpages);
> + kernel_poison_pages(page, numpages, enable);
> }
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 63358d9..c733421 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1002,6 +1002,7 @@ static bool free_pages_prepare(struct page *page, unsigned int order)
> PAGE_SIZE << order);
> }
> arch_free_page(page, order);
> + kernel_poison_pages(page, 1 << order, 0);
> kernel_map_pages(page, 1 << order, 0);
>
> return true;
> @@ -1396,6 +1397,7 @@ static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
> set_page_refcounted(page);
>
> arch_alloc_page(page, order);
> + kernel_poison_pages(page, 1 << order, 1);
> kernel_map_pages(page, 1 << order, 1);
> kasan_alloc_pages(page, order);
>
kernel_map_pages() will fall back to page poisoning scheme for
!ARCH_SUPPORTS_DEBUG_PAGEALLOC.
IIUC, calling kernel_poison_pages() before kernel_map_pages() will be
equivalent to call kernel_poison_pages()
twice?!
Thanks,
Jianyu Zhan
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