Re: [PATCH 2/2] mm/page_alloc.c: add config option to sanitize freed pages

[Andi Kleen]

Anisse Astier <anisse@xxxxxxxxx> writes:
> +	  If unsure, say N.
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 05fcec9..c71440a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -803,6 +803,11 @@ static bool free_pages_prepare(struct page *page, unsigned int order)
>  		debug_check_no_obj_freed(page_address(page),
>  					   PAGE_SIZE << order);
>  	}
> +
> +#ifdef CONFIG_SANITIZE_FREED_PAGES
> +	zero_pages(page, order);
> +#endif

And not removing the clear on __GFP_ZERO by remembering that?

That means all clears would be done twice. 

That patch is far too simple. Clearing is commonly the most
expensive kernel operation.

-Andi

-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only
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