RE: [PATCH 1/3] zram: force disksize setting before using zram

[Dan Magenheimer <dan.magenheimer@oracle.com>]

> From: Greg Kroah-Hartman [mailto:gregkh@linuxfoundation.org]
> Sent: Thursday, January 17, 2013 5:42 PM
> To: Minchan Kim
> Cc: linux-mm@kvack.org; linux-kernel@vger.kernel.org; Nitin Gupta; Seth Jennings; Dan Magenheimer;
> Konrad Rzeszutek Wilk; Jerome Marchand; Pekka Enberg
> Subject: Re: [PATCH 1/3] zram: force disksize setting before using zram
> 
> On Thu, Jan 17, 2013 at 11:12:47AM +0900, Minchan Kim wrote:
> > Now zram document syas "set disksize is optional"
> > but partly it's wrong. When you try to use zram firstly after
> > booting, you must set disksize, otherwise zram can't work because
> > zram gendisk's size is 0. But once you do it, you can use zram freely
> > after reset because reset doesn't reset to zero paradoxically.
> > So in this time, disksize setting is optional.:(
> > It's inconsitent for user behavior and not straightforward.
> >
> > This patch forces always setting disksize firstly before using zram.
> > Yes. It changes current behavior so someone could complain when
> > he upgrades zram. Apparently it could be a problem if zram is mainline
> > but it still lives in staging so behavior could be changed for right
> > way to go. Let them excuse.
> 
> I don't know about changing this behavior.  I need some acks from some
> of the other zram developers before I can take this, or any of the other
> patches in this series.

I'm not officially a zram developer, but I have used it and I
am knowledgeable about in-kernel compression and know the specific
problem being fixed here.  Unless/until compression is much
more tightly integrated into MM policies and "z*" can manage
space more dynamically, Minchan's patch seems to be a good way
to go, especially since zram has found a solid niche in the
embedded (no swap disk) community.  So FWIW:

Acked-by: Dan Magenheimer <dan.magenheimer@oracle.com>

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