Re: [PATCH v1 0/6] fs/proc: move page_mapcount() to fs/proc/internal.h

Oscar Salvador
2024-06-07T13:18:45Z

On Fri, Jun 07, 2024 at 02:23:51PM +0200, David Hildenbrand wrote:
> With all other page_mapcount() users in the tree gone, move
> page_mapcount() to fs/proc/internal.h, rename it and extend the
> documentation to prevent future (ab)use.
>
> ... of course, I find some issues while working on that code that I sort
> first ;)
>
> We'll now only end up calling page_mapcount()
> [now folio_precise_page_mapcount()] on pages mapped via present page table
> entries. Except for /proc/kpagecount, that still does questionable things,
> but we'll leave that legacy interface as is for now.
>
> Did a quick sanity check. Likely we would want some better selfestest
> for /proc/$/pagemap + smaps. I'll see if I can find some time to write
> some more.

I stumbled upon some of these issues while unifying .{pud/pmd}_entry and
.hugetlb_entry.
I am not sure what is the current state of pagemap/smaps selftest, but
since I am going to need them anyway to keep me in check and making sure
I do not break anything hugetlb-related, I might as well write some of
them.

--
Oscar Salvador
SUSE Labs