Re: [PATCH v14 011/138] mm/lru: Add folio LRU functions

Mike Rapoport
2021-07-21T14:36:20Z

On Wed, Jul 21, 2021 at 12:23:09PM +0100, Matthew Wilcox wrote:
> On Wed, Jul 21, 2021 at 11:39:15AM +0300, Mike Rapoport wrote:
> > On Wed, Jul 21, 2021 at 05:08:44AM +0100, Matthew Wilcox wrote:
> > > I wanted to turn those last two sentences into a list, but my
> > > kernel-doc-fu abandoned me. Feel free to submit a follow-on patch to
> > > fix that ;-)
> >
> > Here it is ;-)
>
> Did you try it? Here's what that turns into with htmldoc:

Yes, but I was so happy to see bullets that I missed the fact they are in
the wrong section :(

> Description
>
> We would like to get this info without a page flag, but the state needs
> to survive until the folio is last deleted from the LRU, which could be
> as far down as __page_cache_release.
>
> * 1 if folio is a regular filesystem backed page cache folio or a
> lazily freed anonymous folio (e.g. via MADV_FREE).
> * 0 if folio is a normal anonymous folio, a tmpfs folio or otherwise
> ram or swap backed folio.
>
> Return
>
> An integer (not a boolean!) used to sort a folio onto the right LRU list
> and to account folios correctly.
>
> Yes, we get a bulleted list, but it's placed in the wrong section!
>
> Adding linux-doc for additional insight into this problem.
> For their reference, here's the input:
>
> /**
> * folio_is_file_lru - Should the folio be on a file LRU or anon LRU?
> * @folio: The folio to test.
> *
> * We would like to get this info without a page flag, but the state
> * needs to survive until the folio is last deleted from the LRU, which
> * could be as far down as __page_cache_release.
> *
> * Return: An integer (not a boolean!) used to sort a folio onto the
> * right LRU list and to account folios correctly.
> *
> * - 1 if @folio is a regular filesystem backed page cache folio
> * or a lazily freed anonymous folio (e.g. via MADV_FREE).
> * - 0 if @folio is a normal anonymous folio, a tmpfs folio or otherwise
> * ram or swap backed folio.
> */
> static inline int folio_is_file_lru(struct folio *folio)

Hmm, there is some contradiction between kernel-doc assumption that
anything after a blank line is the default (i.e. Description) section and
the sphynx ideas where empty blank lines should be:

if ($state == STATE_BODY_WITH_BLANK_LINE && /^\s*\*\s?\S/) {
dump_section($file, $section, $contents);
$section = $section_default;
$new_start_line = $.;
$contents = "";
}

(from scripts/kernel-doc::process_body())

--
Sincerely yours,
Mike.