linux-kernel - 回复：[PATCH] mm: hugetlb: fix type of delta parameter in gather_surplus

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Date:   Thu, 19 Nov 2020 17:18:44 +0800
From:   "liu xiang" <liu.xiang@...ngsmart.com>
To:     "linux-mm" <linux-mm@...ck.org>,
        "Mike Kravetz" <mike.kravetz@...cle.com>
Cc:     "akpm" <akpm@...ux-foundation.org>,
        "linux-kernel" <linux-kernel@...r.kernel.org>,
        "liuxiang_1999" <liuxiang_1999@....com>,
        "pan jiagen" <pan.jiagen@...ngsmart.com>
Subject: 回复：[PATCH] mm: hugetlb: fix type of delta parameter in gather_surplus_pages()

Thanks for your advice. I will send a v2 patch.

------------------------------------------------------------------
发件人：Mike Kravetz <mike.kravetz@...cle.com>
发送时间：2020年11月19日(星期四) 02:44
收件人：liu xiang <liu.xiang@...ngsmart.com>; linux-mm <linux-mm@...ck.org>
抄　送：akpm <akpm@...ux-foundation.org>; linux-kernel <linux-kernel@...r.kernel.org>; liuxiang_1999 <liuxiang_1999@....com>; pan jiagen <pan.jiagen@...ngsmart.com>
主　题：Re: [PATCH] mm: hugetlb: fix type of delta parameter in gather_surplus_pages()


On 11/18/20 5:14 AM, Liu Xiang wrote:
> On 64-bit machine, delta variable in hugetlb_acct_memory() may be larger
> than 0xffffffff, but gather_surplus_pages() can only use the low 32-bit
> value now.
> 
> Reported-by: Ma Chenggong <ma.chenggong@...ngsmart.com>
> Signed-off-by: Liu Xiang <liu.xiang@...ngsmart.com>
> Signed-off-by: Pan Jiagen <pan.jiagen@...ngsmart.com>
> ---
>  mm/hugetlb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 37f15c3..293b36d 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1943,7 +1943,7 @@ struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
>   * Increase the hugetlb pool such that it can accommodate a reservation
>   * of size 'delta'.
>   */
> -static int gather_surplus_pages(struct hstate *h, int delta)
> +static int gather_surplus_pages(struct hstate *h, long delta)
>   __must_hold(&hugetlb_lock)
>  {
>   struct list_head surplus_list;

Thank you for noticing the type difference.

However, if the parameter delta is changed to long then we should also change
the local variables in gather_surplus_pages that are used with delta.
Specifically, the local variables 'needed', 'allocated' and 'i' should also be
of type long.
-- 
Mike Kravetz