Re: [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@xxxxxxxxxxxxxxxxx>
> > Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxxxx/