Re: why are some low-level MM routines being exported?

[Minchan Kim <minchan.kim@gmail.com>]

Sorry for mistake of previous reply. 

On Sun, 2010-04-04 at 20:03 +0400, Evgeniy Polyakov wrote:
> On Mon, Apr 05, 2010 at 12:59:44AM +0900, Minchan Kim (minchan.kim@gmail.com) wrote:
> > > perusing the code in mm/filemap.c and i'm curious as to why routines
> > > like, for example, add_to_page_cache_lru() are being exported.  is it
> > > really expected that loadable modules might access routines like that
> > > directly?
> > 
> > It is added by 18bc0bbd162e3 for pohmelfs and now used by logfs, too. 
> > I didn't noticed that at that time.
> > With git log, any mm guys didn't add Signed-off-by or Reviewed-by.
> > 
> > I think it's not good for file system or module to use it directly. 
> > It would make LRU management harder. 
> 
> How come?

What I have a concern is that if file systems or some modules start to
overuse it to manage pages LRU directly, some mistake of them would make
system global LRU stupid and make system wrong. 

> 
> > Is it really needed? Let's think again. 
> 
> Yes, it is really needed. It is not a some king of low-level mm magic to
> export, but a useful interface to work with LRU lists instead of
> copy-paste it into own machinery.
> 
Until now, other file system don't need it. 
Why do you need?

I don't oppose it. 
Let's think again with other guys if we really need it.

-- 
Kind regards,
Minchan Kim


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