[PATCH 3/3] mm: Add kernel PTE level pagetable pages account

[Baolin Wang]

On 7/6/2022 11:45 PM, Matthew Wilcox wrote:
> On Wed, Jul 06, 2022 at 04:59:17PM +0800, Baolin Wang wrote:
>> Now the kernel PTE level ptes are always protected by mm->page_table_lock
>> instead of split pagetable lock, so the kernel PTE level pagetable pages
>> are not accounted. Especially the vmalloc()/vmap() can consume lots of
>> kernel pagetable, so to get an accurate pagetable accounting, calling new
>> helpers page_{set,clear}_pgtable() when allocating or freeing a kernel
>> PTE level pagetable page.
>>
>> Meanwhile converting architectures to use corresponding generic PTE pagetable
>> allocation and freeing functions.
>>
>> Note this patch only adds accounting to the page tables allocated after boot.
>>
>> Signed-off-by: Baolin Wang <baolin.wang at linux.alibaba.com>
>> Reported-by: kernel test robot <oliver.sang at intel.com>
> 
> What does this Reported-by: even mean?  the kernel test robot told you
> that the page tables weren't being accounted?

I fixed an issue reported by this robot. OK, I can remove the tag.

> I don't understand why we want to start accounting kernel page tables.
> an we have a *discussion* about that with a sensible thread name instead
> of just trying to sneak it in as patch 3/3?

I think I have replied to you in below link [1]. The reason is we should 
keep consistent with PMD or PUD pagetable allocation.

[1] 
https://lore.kernel.org/all/68a5286b-7ff3-2c4e-1ab2-305e7860a2f3@linux.alibaba.com/