Re: [RFC PATCH v3 2/3] mm: Add PUD level pagetable account

Baolin Wang
2022-07-03T15:07:52Z

On 7/3/2022 10:52 PM, Matthew Wilcox wrote:
> On Sun, Jul 03, 2022 at 10:06:32PM +0800, Baolin Wang wrote:
>> So for kernel pte page table allocation, I need another similar helpers like
>> below. However they do the samething with
>> pgtable_pud_page_ctor/pgtable_pud_page_dtor, so I am not sure this is good
>> for adding these duplicate code.
>
> Why do we want to account kernel PTE page tables in NR_PAGETABLE?
> I think that's confusing.

Why this will confuse you? I think it is inconsistent that kernel PTE
page tables are not accounted, because we will account PMD/PUD level
page tables no matter they are userspace pagetable pages or kernel
pagetable pages.

Moreover the the vmalloc()/vmap() can consume some kernel pagetable
pages, which should be accounted.