linux-kernel - Re: [PATCH v2] doc: document scope NOFS, NOIO APIs

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Message-ID: <20180529123704.GT27180@dhcp22.suse.cz>
Date:   Tue, 29 May 2018 14:37:04 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Jonathan Corbet <corbet@....net>
Cc:     Dave Chinner <david@...morbit.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v2] doc: document scope NOFS, NOIO APIs

On Tue 29-05-18 05:51:58, Jonathan Corbet wrote:
> On Tue, 29 May 2018 10:26:44 +0200
> Michal Hocko <mhocko@...nel.org> wrote:
> 
> > Although the api is documented in the source code Ted has pointed out
> > that there is no mention in the core-api Documentation and there are
> > people looking there to find answers how to use a specific API.
> 
> So, I still think that this:
> 
> > +The traditional way to avoid this deadlock problem is to clear __GFP_FS
> > +respectively __GFP_IO (note the latter implies clearing the first as well) in
> 
> doesn't read the way you intend it to.  But we've sent you in more
> than enough circles on this already, so I went ahead and applied it;
> wording can always be tweaked later.

Thanks a lot Jonathan! I am open to any suggestions of course and can
follow up with some refinements. Just for the background. The above
paragraph is meant to say that:
- clearing __GFP_FS is a way to avoid reclaim recursion into filesystems
  deadlocks
- clearing __GFP_IO is a way to avoid reclaim recursion into the IO
  layer deadlocks
- GFP_NOIO implies __GFP_NOFS

> You added the kerneldoc comments, but didn't bring them into your new
> document.  I'm going to tack this on afterward, hopefully nobody will
> object.

I have to confess I've never studied how the rst and kerneldoc should be
interlinked so thanks for the fix up!
-- 
Michal Hocko
SUSE Labs