On Tue, Nov 30, 2021 at 10:39PM +0100, andrey.konovalov@xxxxxxxxx wrote:
> From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
>
> Simplify the code around calling kasan_poison_pages() in
> free_pages_prepare().
>
> Reording kasan_poison_pages() and kernel_init_free_pages() is OK,
> since kernel_init_free_pages() can handle poisoned memory.
Why did they have to be reordered?
> This patch does no functional changes besides reordering the calls.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> ---
> mm/page_alloc.c | 18 +++++-------------
> 1 file changed, 5 insertions(+), 13 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3f3ea41f8c64..0673db27dd12 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1289,6 +1289,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
> {
> int bad = 0;
> bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
skip_kasan_poison is only used once now, so you could remove the
variable -- unless later code will use it in more than once place again.
> + bool init = want_init_on_free();
>
> VM_BUG_ON_PAGE(PageTail(page), page);
>
> @@ -1359,19 +1360,10 @@ static __always_inline bool free_pages_prepare(struct page *page,
> * With hardware tag-based KASAN, memory tags must be set before the
> * page becomes unavailable via debug_pagealloc or arch_free_page.
> */
> - if (kasan_has_integrated_init()) {
> - bool init = want_init_on_free();
> -
> - if (!skip_kasan_poison)
> - kasan_poison_pages(page, order, init);
> - } else {
> - bool init = want_init_on_free();
> -
> - if (init)
> - kernel_init_free_pages(page, 1 << order);
> - if (!skip_kasan_poison)
> - kasan_poison_pages(page, order, init);
> - }
> + if (!skip_kasan_poison)
> + kasan_poison_pages(page, order, init);
> + if (init && !kasan_has_integrated_init())
> + kernel_init_free_pages(page, 1 << order);
>
> /*
> * arch_free_page() can make the page's contents inaccessible. s390
> --
> 2.25.1
