Re: [PATCH 2/3] mm: remove unused zpool layer

[Johannes Weiner <hannes@cmpxchg.org>]

On Fri, Sep 05, 2025 at 06:58:47PM +0000, Yosry Ahmed wrote:
> On Fri, Aug 29, 2025 at 05:15:27PM +0100, Johannes Weiner wrote:
> > With zswap using zsmalloc directly, there are no more in-tree users of
> > this code. Remove it.
> > 
> > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> > ---
> [..]
> > @@ -125,45 +122,18 @@ config ZSWAP_COMPRESSOR_DEFAULT
> >         default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
> >         default ""
> >  
> > -choice
> > -	prompt "Default allocator"
> > -	depends on ZSWAP
> > -	default ZSWAP_ZPOOL_DEFAULT_ZSMALLOC if MMU
> > -	help
> > -	  Selects the default allocator for the compressed cache for
> > -	  swap pages.
> > -	  The default is 'zbud' for compatibility, however please do
> > -	  read the description of each of the allocators below before
> > -	  making a right choice.
> > -
> > -	  The selection made here can be overridden by using the kernel
> > -	  command line 'zswap.zpool=' option.
> > +config ZSMALLOC
> > +	tristate
> >  
> > -config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
> > -	bool "zsmalloc"
> > -	select ZSMALLOC
> > -	help
> > -	  Use the zsmalloc allocator as the default allocator.
> > -endchoice
> > +if ZSMALLOC
> >  
> > -config ZSWAP_ZPOOL_DEFAULT
> > -       string
> > -       depends on ZSWAP
> > -       default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
> > -       default ""
> > +menu "Zsmalloc allocator options"
> > +	depends on ZSMALLOC
> >  
> > -config ZSMALLOC
> > -	tristate
> > -	prompt "N:1 compression allocator (zsmalloc)" if (ZSWAP || ZRAM)
> > -	depends on MMU
> > -	help
> > -	  zsmalloc is a slab-based memory allocator designed to store
> > -	  pages of various compression levels efficiently. It achieves
> > -	  the highest storage density with the least amount of fragmentation.
> 
> Why remove the prompt and help text here?

We shouldn't ask users unnecessary questions. Zswap and zram are the
user-visible kernel options; if one of them is selected, they should
just quietly pull in the zsmalloc code.