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Subject: Re: [PATCH] page_poison: plays nicely with KASAN
To:     Qian Cai <cai@lca.pw>, akpm@linux-foundation.org
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <20190107223636.80593-1-cai@lca.pw>
From:   Andrey Ryabinin <aryabinin@virtuozzo.com>
Message-ID: <2e46c139-70d3-dc86-28c9-a9f263651b57@virtuozzo.com>
Date:   Fri, 11 Jan 2019 21:45:25 +0300
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On 1/8/19 1:36 AM, Qian Cai wrote:

>  
> diff --git a/mm/page_poison.c b/mm/page_poison.c
> index f0c15e9017c0..e546b70e592a 100644
> --- a/mm/page_poison.c
> +++ b/mm/page_poison.c
> @@ -6,6 +6,7 @@
>  #include <linux/page_ext.h>
>  #include <linux/poison.h>
>  #include <linux/ratelimit.h>
> +#include <linux/kasan.h>
>  
>  static bool want_page_poisoning __read_mostly;
>  
> @@ -40,6 +41,7 @@ static void poison_page(struct page *page)
>  {
>  	void *addr = kmap_atomic(page);
>  
> +	kasan_unpoison_shadow(addr, PAGE_SIZE);
>  	memset(addr, PAGE_POISON, PAGE_SIZE);

kasan_disable/enable_current() should be slightly more efficient for this case.

>  	kunmap_atomic(addr);
>  }
>