[PATCH] mm: hugetlb: fix type of delta parameter in gather_surplus_pages()

[PATCH] mm: hugetlb: fix type of delta parameter in gather_surplus_pages()

[Liu Xiang]

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@zlingsmart.com>
Signed-off-by: Liu Xiang <liu.xiang@zlingsmart.com>
Signed-off-by: Pan Jiagen <pan.jiagen@zlingsmart.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;
-- 
1.9.1

Re: [PATCH] mm: hugetlb: fix type of delta parameter in gather_surplus_pages()

[Mike Kravetz]

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@zlingsmart.com>
> Signed-off-by: Liu Xiang <liu.xiang@zlingsmart.com>
> Signed-off-by: Pan Jiagen <pan.jiagen@zlingsmart.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

回复：[PATCH] mm: hugetlb: fix type of delta parameter in gather_surplus_pages()

[liu xiang]

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

------------------------------------------------------------------
发件人：Mike Kravetz <mike.kravetz@oracle.com>
发送时间：2020年11月19日(星期四) 02:44
收件人：liu xiang <liu.xiang@zlingsmart.com>; linux-mm <linux-mm@kvack.org>
抄　送：akpm <akpm@linux-foundation.org>; linux-kernel <linux-kernel@vger.kernel.org>; liuxiang_1999 <liuxiang_1999@126.com>; pan jiagen <pan.jiagen@zlingsmart.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@zlingsmart.com>
> Signed-off-by: Liu Xiang <liu.xiang@zlingsmart.com>
> Signed-off-by: Pan Jiagen <pan.jiagen@zlingsmart.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