Re: [PATCH v4 45/66] acct: Use VMA iterator instead of linked list

[Vlastimil Babka <vbabka@xxxxxxx>]

On 12/1/21 15:30, Liam Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
> 
> The VMA iterator is faster than the linked list.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
>  kernel/acct.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/acct.c b/kernel/acct.c
> index 3df53cf1dcd5..2e7bf8d41f04 100644
> --- a/kernel/acct.c
> +++ b/kernel/acct.c
> @@ -535,15 +535,14 @@ void acct_collect(long exitcode, int group_dead)
>  	unsigned long vsize = 0;
>  
>  	if (group_dead && current->mm) {
> +		struct mm_struct *mm = current->mm;
> +		VMA_ITERATOR(vmi, mm, 0);
>  		struct vm_area_struct *vma;
>  
> -		mmap_read_lock(current->mm);
> -		vma = current->mm->mmap;
> -		while (vma) {
> +		mmap_read_lock(mm);
> +		for_each_vma(vmi, vma)
>  			vsize += vma->vm_end - vma->vm_start;
> -			vma = vma->vm_next;
> -		}
> -		mmap_read_unlock(current->mm);
> +		mmap_read_unlock(mm);
>  	}
>  
>  	spin_lock_irq(&current->sighand->siglock);