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From:   Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Date:   Fri, 10 Apr 2020 11:38:45 +0900
To:     Minchan Kim <minchan@kernel.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Christoph Hellwig <hch@lst.de>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, x86@kernel.org,
        David Airlie <airlied@linux.ie>,
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        Laura Abbott <labbott@redhat.com>,
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        sergey.senozhatsky@gmail.com
Subject: Re: [PATCH 10/28] mm: only allow page table mappings for built-in
 zsmalloc
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On (20/04/09 10:08), Minchan Kim wrote:
> > > Even though I don't know how many usecase we have using zsmalloc as
> > > module(I heard only once by dumb reason), it could affect existing
> > > users. Thus, please include concrete explanation in the patch to
> > > justify when the complain occurs.
> > 
> > The justification is 'we can unexport functions that have no sane reason
> > of being exported in the first place'.
> > 
> > The Changelog pretty much says that.
> 
> Okay, I hope there is no affected user since this patch.
> If there are someone, they need to provide sane reason why they want
> to have zsmalloc as module.

I'm one of those who use zsmalloc as a module - mainly because I use zram
as a compressing general purpose block device, not as a swap device.
I create zram0, mkfs, mount, checkout and compile code, once done -
umount, rmmod. This reduces the number of writes to SSD. Some people use
tmpfs, but zram device(-s) can be much larger in size. That's a niche use
case and I'm not against the patch.

	-ss