linux-kernel - Re: [PATCH] mm: kfence: fix handling discontiguous page

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Date:   Fri, 24 Mar 2023 11:43:12 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Muchun Song <songmuchun@...edance.com>, <glider@...gle.com>,
        <elver@...gle.com>, <dvyukov@...gle.com>,
        <akpm@...ux-foundation.org>, <jannh@...gle.com>,
        <sjpark@...zon.de>, <muchun.song@...ux.dev>
CC:     <kasan-dev@...glegroups.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: kfence: fix handling discontiguous page



On 2023/3/23 10:50, Muchun Song wrote:
> The struct pages could be discontiguous when the kfence pool is allocated
> via alloc_contig_pages() with CONFIG_SPARSEMEM and !CONFIG_SPARSEMEM_VMEMMAP.
> So, the iteration should use nth_page().
> 

Reviewed-by: Kefeng Wang <wangkefeng.wang@...wei.com>

> Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
> Signed-off-by: Muchun Song <songmuchun@...edance.com>
> ---
>   mm/kfence/core.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/kfence/core.c b/mm/kfence/core.c
> index d66092dd187c..1065e0568d05 100644
> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -556,7 +556,7 @@ static unsigned long kfence_init_pool(void)
>   	 * enters __slab_free() slow-path.
>   	 */
>   	for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) {
> -		struct slab *slab = page_slab(&pages[i]);
> +		struct slab *slab = page_slab(nth_page(pages, i));
>   
>   		if (!i || (i % 2))
>   			continue;
> @@ -602,7 +602,7 @@ static unsigned long kfence_init_pool(void)
>   
>   reset_slab:
>   	for (i = 0; i < KFENCE_POOL_SIZE / PAGE_SIZE; i++) {
> -		struct slab *slab = page_slab(&pages[i]);
> +		struct slab *slab = page_slab(nth_page(pages, i));
>   
>   		if (!i || (i % 2))
>   			continue;