Re: [PATCH] Documentation/mm: Initial page table documentation

[Mike Rapoport <rppt@kernel.org>]

On Thu, Jun 08, 2023 at 10:13:49AM +0200, Linus Walleij wrote:
> Hi Matthew,
> 
> I fixes up most of the comments.
> 
> On Tue, Jun 6, 2023 at 5:57 AM Matthew Wilcox <willy@infradead.org> wrote:
> > On Tue, Jun 06, 2023 at 12:10:35AM +0200, Linus Walleij wrote:
> 
> > > +- **pte**, `pte_t`, `pteval_t` = **Page Table Entry** - mentioned earlier.
> > > +  The name is a bit confusing because while in Linux 1.0 this did refer to a
> > > +  single page table entry in the top level page table, it was retrofitted
> > > +  to be "what the level above points to". So when two-level page tables were
> > > +  introduced, the *pte* became a list of pointers, which is why
> > > +  `PTRS_PER_PTE` exists. This oxymoronic term can be mildly confusing.
> >
> > I don't think this is right.  PTRS_PER_PTE is how many pointers are in
> > the PMD page table,
> 
> I don't get this. What does PTRS_PER_PMD mean then (and
> then all the way up to PTRS_PER_PGD...)

PTRS_PER_PTE is how many pointers in the lowest level (pte) page table and
pte_t is a "pointer" to an actual physical page mapped by the page tables.
 
> Yours,
> Linus Walleij

-- 
Sincerely yours,
Mike.