Re: [PATCH v14 67/70] mm/vmscan: Use vma iterator instead of vm_next

From: Andrew Morton
Date: Mon Sep 12 2022 - 15:46:09 EST


On Mon, 12 Sep 2022 00:55:08 -0600 Yu Zhao <yuzhao@xxxxxxxxxx> wrote:

>
> The following should work properly. Please take a look. Thanks!
>
> ---
> mm/vmscan.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 11a86d47e85e..b22d3efe3031 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -3776,23 +3776,17 @@ static bool get_next_vma(unsigned long mask, unsigned long size, struct mm_walk
> {
> unsigned long start = round_up(*vm_end, size);
> unsigned long end = (start | ~mask) + 1;
> + VMA_ITERATOR(vmi, args->mm, start);
>
> VM_WARN_ON_ONCE(mask & size);
> VM_WARN_ON_ONCE((start & mask) != (*vm_start & mask));
>
> - while (args->vma) {
> - if (start >= args->vma->vm_end) {
> - args->vma = args->vma->vm_next;
> - continue;
> - }
> -
> + for_each_vma(vmi, args->vma) {
> if (end && end <= args->vma->vm_start)
> return false;
>
> - if (should_skip_vma(args->vma->vm_start, args->vma->vm_end, args)) {
> - args->vma = args->vma->vm_next;
> + if (should_skip_vma(args->vma->vm_start, args->vma->vm_end, args))
> continue;
> - }
>
> *vm_start = max(start, args->vma->vm_start);
> *vm_end = min(end - 1, args->vma->vm_end - 1) + 1;

What does this apply to? It's almost what is in mm-unstable/linux-next
at present?

static bool get_next_vma(unsigned long mask, unsigned long size, struct mm_walk *args,
unsigned long *vm_start, unsigned long *vm_end)
{
unsigned long start = round_up(*vm_end, size);
unsigned long end = (start | ~mask) + 1;
VMA_ITERATOR(vmi, args->mm, start);

VM_WARN_ON_ONCE(mask & size);
VM_WARN_ON_ONCE((start & mask) != (*vm_start & mask));

for_each_vma_range(vmi, args->vma, end) {
if (should_skip_vma(args->vma->vm_start, args->vma->vm_end, args))
continue;

*vm_start = max(start, args->vma->vm_start);
*vm_end = min(end - 1, args->vma->vm_end - 1) + 1;

return true;
}

return false;
}

for_each_vma_range versus for_each_vma.