Re: [PATCH] staging: zsmalloc: Ensure handle is never 0 on success

Hugh Dickins
2013-11-14T04:01:09Z

On Wed, 13 Nov 2013, Minchan Kim wrote:
> On Thu, Nov 07, 2013 at 04:04:51PM +0900, Minchan Kim wrote:
> > On Wed, Nov 06, 2013 at 07:05:11PM -0800, Greg KH wrote:
> > > On Wed, Nov 06, 2013 at 03:46:19PM -0800, Nitin Gupta wrote:
> > > > I'm getting really tired of them hanging around in here for many years
> > > > > now...
> > > > >
> > > >
> > > > Minchan has tried many times to promote zram out of staging. This was
> > > > his most recent attempt:
> > > >
> > > > https://lkml.org/lkml/2013/8/21/54
...
>
> Hello Andrew,
>
> I'd like to listen your opinion.
>
> The zram promotion trial started since Aug 2012 and I already have get many
> Acked/Reviewed feedback and positive feedback from Rik and Bob in this thread.
> (ex, Jens Axboe[1], Konrad Rzeszutek Wilk[2], Nitin Gupta[3], Pekka Enberg[4])
> In Linuxcon, Hugh gave positive feedback about zram(Hugh, If I misunderstood,
> please correct me!). And there are lots of users already in embedded industry
> ex, (most of TV in the world, Chromebook, CyanogenMod, Android Kitkat.)
> They are not idiot. Zram is really effective for embedded world.

Sorry for taking so long to respond, Minchan: no, you do not misrepresent
me at all. Promotion of zram and zsmalloc from staging is way overdue:
they long ago proved their worth, look tidy, and have an active maintainer.

Putting them into drivers/staging was always a mistake, and I quite
understand Greg's impatience with them by now; but please let's move
them to where they belong instead of removing them.

I would not have lent support to zswap if I'd thought that was going to
block zram. And I was not the only one surprised when zswap replaced its
use of zsmalloc by zbud: we had rather expected a zbud option to be added,
and I still assume that zsmalloc support will be added back to zswap later.

I think your August 2013 posting moved zsmalloc under zram and moved it
all to drivers/block? That is the right place for zram, but I do think
zsmalloc.c (I'm not very keen on _drvs and -mains myself) should be
alongside zbud.c in mm, where we can better keep an eye on its
struct-pageyness.

IMHO
Hugh

>
> We spent much time with preventing zram enhance since it have been in staging
> and Greg never want to improve without promotion.
>
> Please consider promotion and let us improve it.
> I think only remained thing is your decision.
>
>
> 1. https://lkml.org/lkml/2012/9/11/551
> 2. https://lkml.org/lkml/2012/8/9/636
> 3. https://lkml.org/lkml/2012/8/8/390
> 4. https://lkml.org/lkml/2012/9/26/126