* [PATCH] mm/hugetlb: remove redundant reservation check condition in alloc_huge_page()
@ 2021-02-10 7:54 Miaohe Lin
2021-02-13 1:15 ` Mike Kravetz
0 siblings, 1 reply; 3+ messages in thread
From: Miaohe Lin @ 2021-02-10 7:54 UTC (permalink / raw)
To: akpm, mike.kravetz; +Cc: linux-mm, linux-kernel, linmiaohe
If there is no reservation corresponding to a vma, map_chg is always != 0,
i.e. we can not meet the condition where a vma does not have reservation
while map_chg = 0.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/hugetlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4f2c92ddbca4..36c3646fa55f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2311,7 +2311,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
/* If this allocation is not consuming a reservation, charge it now.
*/
- deferred_reserve = map_chg || avoid_reserve || !vma_resv_map(vma);
+ deferred_reserve = map_chg || avoid_reserve;
if (deferred_reserve) {
ret = hugetlb_cgroup_charge_cgroup_rsvd(
idx, pages_per_huge_page(h), &h_cg);
--
2.19.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] mm/hugetlb: remove redundant reservation check condition in alloc_huge_page()
2021-02-10 7:54 [PATCH] mm/hugetlb: remove redundant reservation check condition in alloc_huge_page() Miaohe Lin
@ 2021-02-13 1:15 ` Mike Kravetz
2021-02-18 2:27 ` Miaohe Lin
0 siblings, 1 reply; 3+ messages in thread
From: Mike Kravetz @ 2021-02-13 1:15 UTC (permalink / raw)
To: Miaohe Lin, akpm; +Cc: linux-mm, linux-kernel
On 2/9/21 11:54 PM, Miaohe Lin wrote:
> If there is no reservation corresponding to a vma, map_chg is always != 0,
> i.e. we can not meet the condition where a vma does not have reservation
> while map_chg = 0.
This commit message might be easier to understand?
vma_resv_map(vma) checks if a reserve map is associated with the vma. The
routine vma_needs_reservation() will check vma_resv_map(vma) and return 1
if no reserv map is present. map_chg is set to the return value of
vma_needs_reservation(). Therefore, !vma_resv_map(vma) is redundant in the
expression:
map_chg || avoid_reserve || !vma_resv_map(vma);
Remove the redundant check.
--
Mike Kravetz
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> mm/hugetlb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 4f2c92ddbca4..36c3646fa55f 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2311,7 +2311,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
>
> /* If this allocation is not consuming a reservation, charge it now.
> */
> - deferred_reserve = map_chg || avoid_reserve || !vma_resv_map(vma);
> + deferred_reserve = map_chg || avoid_reserve;
> if (deferred_reserve) {
> ret = hugetlb_cgroup_charge_cgroup_rsvd(
> idx, pages_per_huge_page(h), &h_cg);
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] mm/hugetlb: remove redundant reservation check condition in alloc_huge_page()
2021-02-13 1:15 ` Mike Kravetz
@ 2021-02-18 2:27 ` Miaohe Lin
0 siblings, 0 replies; 3+ messages in thread
From: Miaohe Lin @ 2021-02-18 2:27 UTC (permalink / raw)
To: Mike Kravetz; +Cc: linux-mm, linux-kernel, Andrew Morton
Hi:
On 2021/2/13 9:15, Mike Kravetz wrote:
> On 2/9/21 11:54 PM, Miaohe Lin wrote:
>> If there is no reservation corresponding to a vma, map_chg is always != 0,
>> i.e. we can not meet the condition where a vma does not have reservation
>> while map_chg = 0.
>
> This commit message might be easier to understand?
>
> vma_resv_map(vma) checks if a reserve map is associated with the vma. The
> routine vma_needs_reservation() will check vma_resv_map(vma) and return 1
> if no reserv map is present. map_chg is set to the return value of
> vma_needs_reservation(). Therefore, !vma_resv_map(vma) is redundant in the
> expression:
> map_chg || avoid_reserve || !vma_resv_map(vma);
> Remove the redundant check.
>
Sorry for late respond! I will use this wonderful commit message. Many thanks! :)
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-02-10 7:54 [PATCH] mm/hugetlb: remove redundant reservation check condition in alloc_huge_page() Miaohe Lin
2021-02-13 1:15 ` Mike Kravetz
2021-02-18 2:27 ` Miaohe Lin
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