Re: [PATCH] bootmem: Stop using page->index

[Matthew Wilcox <willy@infradead.org>]

On Thu, Sep 12, 2024 at 12:04:18PM -0700, Yosry Ahmed wrote:
> On Thu, Sep 12, 2024 at 11:56 AM Matthew Wilcox (Oracle)
> <willy@infradead.org> wrote:
> >
> > Encode the type into the bottom four bits of page->private and the
> > info into the remaining bits.  Also turn the bootmem type into a
> > named enum.

> > @@ -21,9 +20,19 @@ enum {
> >  void __init register_page_bootmem_info_node(struct pglist_data *pgdat);
> >
> >  void get_page_bootmem(unsigned long info, struct page *page,
> > -                     unsigned long type);
> > +               enum bootmem_type type);
> >  void put_page_bootmem(struct page *page);
> >
> > +static inline enum bootmem_type bootmem_type(const struct page *page)
> > +{
> > +       return (unsigned long)page->private & 0xf;
> > +}
> > +
> > +static inline unsigned long bootmem_info(const struct page *page)
> > +{
> > +       return (unsigned long)page->private >> 4;
> > +}
> 
> Would it be better to define the number of bits used for the type as a
> macro and use it throughout (bootmem_type(), bootmem_info(),
> get_page_bootmem())?.

I think this is an adequate abstraction already.