Re: [LSF/MM TOPIC] mm documentation

[Mike Rapoport <rppt@linux.vnet.ibm.com>]

On Tue, Jan 30, 2018 at 02:41:41PM +0100, Michal Hocko wrote:
> On Tue 30-01-18 14:54:44, Mike Rapoport wrote:
> > On Tue, Jan 30, 2018 at 12:50:55PM +0100, Michal Hocko wrote:
> > > On Tue 30-01-18 12:54:50, Mike Rapoport wrote:
> > > > (forgot to CC linux-mm)
> > > > 
> > > > On Tue, Jan 30, 2018 at 12:52:37PM +0200, Mike Rapoport wrote:
> > > > > Hello,
> > > > > 
> > > > > The mm kernel-doc documentation is not in a great shape. 
> > > > > 
> > > > > Some of the existing kernel-doc annotations were not reformatted during
> > > > > transition from dockbook to sphix. Sometimes the parameter descriptions
> > > > > do not match actual code. But aside these rather mechanical issues there
> > > > > are several points it'd like to discuss:
> > > > > 
> > > > > * Currently, only 14 files are linked to kernel-api.rst under "Memory
> > > > > Management in Linux" section. We have more than hundred files only in mm.
> > > > > Even the existing documentation is not generated when running "make
> > > > > htmldocs"
> > > 
> > > Is this documentation anywhere close to be actually useful?
> > 
> > Some parts are documented better, some worse. For instance, bootmem and
> > z3fold are covered not bad at all, but, say, huge_memory has no structured
> > comments at all. Roughly half of the files in mm/ have some documentation,
> > but I didn't yet read that all to say how much of it is actually useful.
> 
> It is good to hear that at least something has a documentation coverage.
> I was asking mostly because I _think_ that the API documentation is far
> from the top priority. 

API documentations is important for kernel developers who are not deeply
involved with mm. When one develops a device driver, knowing how to
allocate and free memory is essential. And, while *malloc are included in
kernel-api.rst, CMA and HMM documentation is not visible.

> We are seriously lacking any highlevel one which describes the design and
> subsytems interaction.

I should have describe it better, but by "creating a new structure for mm
documentation" I've also meant adding high level description.

> Well, we have missed that train years ago. It will be really hard to catch up.

At least we can try.

> -- 
> Michal Hocko
> SUSE Labs
> 

-- 
Sincerely yours,
Mike.

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