On Fri, Jun 10, 2022 at 5:21 PM Catalin Marinas <catalin.marinas@xxxxxxx> wrote:
>
> Currently post_alloc_hook() skips the kasan unpoisoning if the tags will
> be zeroed (__GFP_ZEROTAGS) or __GFP_SKIP_KASAN_UNPOISON is passed. Since
> __GFP_ZEROTAGS is now accompanied by __GFP_SKIP_KASAN_UNPOISON, remove
> the extra check.
>
> Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
> Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> ---
> mm/page_alloc.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index f6ed240870bc..bf45a6aa407a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2361,7 +2361,7 @@ static inline bool check_new_pcp(struct page *page, unsigned int order)
> }
> #endif /* CONFIG_DEBUG_VM */
>
> -static inline bool should_skip_kasan_unpoison(gfp_t flags, bool init_tags)
> +static inline bool should_skip_kasan_unpoison(gfp_t flags)
> {
> /* Don't skip if a software KASAN mode is enabled. */
> if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
> @@ -2373,12 +2373,10 @@ static inline bool should_skip_kasan_unpoison(gfp_t flags, bool init_tags)
> return true;
>
> /*
> - * With hardware tag-based KASAN enabled, skip if either:
> - *
> - * 1. Memory tags have already been cleared via tag_clear_highpage().
> - * 2. Skipping has been requested via __GFP_SKIP_KASAN_UNPOISON.
> + * With hardware tag-based KASAN enabled, skip if this has been
> + * requested via __GFP_SKIP_KASAN_UNPOISON.
> */
> - return init_tags || (flags & __GFP_SKIP_KASAN_UNPOISON);
> + return flags & __GFP_SKIP_KASAN_UNPOISON;
> }
>
> static inline bool should_skip_init(gfp_t flags)
> @@ -2430,7 +2428,7 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
> /* Note that memory is already initialized by the loop above. */
> init = false;
> }
> - if (!should_skip_kasan_unpoison(gfp_flags, init_tags)) {
> + if (!should_skip_kasan_unpoison(gfp_flags)) {
> /* Unpoison shadow memory or set memory tags. */
> kasan_unpoison_pages(page, order, init);
>
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
