2022-04-05 01:45:05

by Yang Shi

Subject: [v3 PATCH 2/8] mm: khugepaged: remove redundant check for VM_NO_KHUGEPAGED

The hugepage_vma_check() called by khugepaged_enter_vma_merge() does
check VM_NO_KHUGEPAGED. Remove the check from caller and move the check
in hugepage_vma_check() up.

More checks may be run for VM_NO_KHUGEPAGED vmas, but MADV_HUGEPAGE is
definitely not a hot path, so cleaner code does outweigh.

Reviewed-by: Miaohe Lin <[email protected]>
Acked-by: Song Liu <[email protected]>
Signed-off-by: Yang Shi <[email protected]>
---
mm/khugepaged.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a4e5eaf3eb01..7d197d9e3258 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -365,8 +365,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
* register it here without waiting a page fault that
* may not happen any time soon.
*/
- if (!(*vm_flags & VM_NO_KHUGEPAGED) &&
- khugepaged_enter_vma_merge(vma, *vm_flags))
+ if (khugepaged_enter_vma_merge(vma, *vm_flags))
return -ENOMEM;
break;
case MADV_NOHUGEPAGE:
@@ -445,6 +444,9 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
if (!transhuge_vma_enabled(vma, vm_flags))
return false;

+ if (vm_flags & VM_NO_KHUGEPAGED)
+ return false;
+
if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
vma->vm_pgoff, HPAGE_PMD_NR))
return false;
@@ -470,7 +472,8 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
return false;
if (vma_is_temporary_stack(vma))
return false;
- return !(vm_flags & VM_NO_KHUGEPAGED);
+
+ return true;
}

int __khugepaged_enter(struct mm_struct *mm)
--
2.26.3

2022-05-09 12:48:10

by Vlastimil Babka

Subject: Re: [v3 PATCH 2/8] mm: khugepaged: remove redundant check for VM_NO_KHUGEPAGED

On 4/4/22 22:02, Yang Shi wrote:
> The hugepage_vma_check() called by khugepaged_enter_vma_merge() does
> check VM_NO_KHUGEPAGED. Remove the check from caller and move the check
> in hugepage_vma_check() up.
>
> More checks may be run for VM_NO_KHUGEPAGED vmas, but MADV_HUGEPAGE is
> definitely not a hot path, so cleaner code does outweigh.
>
> Reviewed-by: Miaohe Lin <[email protected]>
> Acked-by: Song Liu <[email protected]>
> Signed-off-by: Yang Shi <[email protected]>

Acked-by: Vlastimil Babka <[email protected]>

> ---
> mm/khugepaged.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index a4e5eaf3eb01..7d197d9e3258 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -365,8 +365,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
> * register it here without waiting a page fault that
> * may not happen any time soon.
> */
> - if (!(*vm_flags & VM_NO_KHUGEPAGED) &&
> - khugepaged_enter_vma_merge(vma, *vm_flags))
> + if (khugepaged_enter_vma_merge(vma, *vm_flags))
> return -ENOMEM;
> break;
> case MADV_NOHUGEPAGE:
> @@ -445,6 +444,9 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
> if (!transhuge_vma_enabled(vma, vm_flags))
> return false;
>
> + if (vm_flags & VM_NO_KHUGEPAGED)
> + return false;
> +
> if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) -
> vma->vm_pgoff, HPAGE_PMD_NR))
> return false;
> @@ -470,7 +472,8 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
> return false;
> if (vma_is_temporary_stack(vma))
> return false;
> - return !(vm_flags & VM_NO_KHUGEPAGED);
> +
> + return true;
> }
>
> int __khugepaged_enter(struct mm_struct *mm)