linux-kernel - Re: [PATCH v7 03/12] mm/sparsemem: Add helpers track active portions of a section at boot

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Date:   Fri, 3 May 2019 09:31:26 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Logan Gunthorpe <logang@...tatee.com>,
        Jane Chu <jane.chu@...cle.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 03/12] mm/sparsemem: Add helpers track active portions
 of a section at boot

On Thu, May 02, 2019 at 07:03:45AM -0700, Dan Williams wrote:
> > section_active_mask() also converts the value to address/size.
> > Why do we need to convert the values and we cannot work with pfn/pages instead?
> > It should be perfectly possible unless I am missing something.
> >
> > The only thing required would be to export earlier your:
> >
> > +#define PAGES_PER_SUB_SECTION (SECTION_ACTIVE_SIZE / PAGE_SIZE)
> > +#define PAGE_SUB_SECTION_MASK (~(PAGES_PER_SUB_SECTION-1))
> >
> > and change section_active_index to:
> >
> > static inline int section_active_index(unsigned long pfn)
> > {
> >         return (pfn & ~(PAGE_SECTION_MASK)) / SUB_SECTION_ACTIVE_PAGES;

Sorry, here I meant:

return (pfn & ~(PAGE_SECTION_MASK)) / PAGES_PER_SUB_SECTION;

But I think you got the idea :-)

-- 
Oscar Salvador
SUSE L3