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Date:   Sun, 3 Jul 2022 23:07:47 +0800
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Subject: Re: [RFC PATCH v3 2/3] mm: Add PUD level pagetable account
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Mike Rapoport <rppt@linux.ibm.com>, akpm@linux-foundation.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
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From:   Baolin Wang <baolin.wang@linux.alibaba.com>
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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.