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Date:   Wed, 23 Nov 2022 17:21:42 -0800
From:   Roman Gushchin <roman.gushchin@linux.dev>
To:     Vlastimil Babka <vbabka@suse.cz>
Cc:     Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Pekka Enberg <penberg@kernel.org>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>, patches@lists.linux.dev,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Russell King <linux@armlinux.org.uk>,
        Aaro Koskinen <aaro.koskinen@iki.fi>,
        Janusz Krzysztofik <jmkrzyszt@gmail.com>,
        Tony Lindgren <tony@atomide.com>,
        Jonas Bonn <jonas@southpole.se>,
        Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
        Stafford Horne <shorne@gmail.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, Arnd Bergmann <arnd@arndb.de>,
        Josh Triplett <josh@joshtriplett.org>,
        Conor Dooley <conor@kernel.org>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org,
        openrisc@lists.librecores.org, linux-riscv@lists.infradead.org,
        linux-sh@vger.kernel.org
Subject: Re: [PATCH 12/12] mm, slob: rename CONFIG_SLOB to
 CONFIG_SLOB_DEPRECATED
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References: <20221121171202.22080-1-vbabka@suse.cz>
 <20221121171202.22080-13-vbabka@suse.cz>
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On Mon, Nov 21, 2022 at 06:12:02PM +0100, Vlastimil Babka wrote:
> As explained in [1], we would like to remove SLOB if possible.
> 
> - There are no known users that need its somewhat lower memory footprint
>   so much that they cannot handle SLUB (after some modifications by the
>   previous patches) instead.
> 
> - It is an extra maintenance burden, and a number of features are
>   incompatible with it.
> 
> - It blocks the API improvement of allowing kfree() on objects allocated
>   via kmem_cache_alloc().
> 
> As the first step, rename the CONFIG_SLOB option in the slab allocator
> configuration choice to CONFIG_SLOB_DEPRECATED. Add CONFIG_SLOB
> depending on CONFIG_SLOB_DEPRECATED as an internal option to avoid code
> churn. This will cause existing .config files and defconfigs with
> CONFIG_SLOB=y to silently switch to the default (and recommended
> replacement) SLUB, while still allowing SLOB to be configured by anyone
> that notices and needs it. But those should contact the slab maintainers
> and linux-mm@kvack.org as explained in the updated help. With no valid
> objections, the plan is to update the existing defconfigs to SLUB and
> remove SLOB in a few cycles.
> 
> To make SLUB more suitable replacement for SLOB, a CONFIG_SLUB_TINY
> option was introduced to limit SLUB's memory overhead.
> There is a number of defconfigs specifying CONFIG_SLOB=y. As part of
> this patch, update them to select CONFIG_SLUB and CONFIG_SLUB_TINY.
> 
> [1] https://lore.kernel.org/all/b35c3f82-f67b-2103-7d82-7a7ba7521439@suse.cz/
> 
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
> Cc: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Jonas Bonn <jonas@southpole.se>
> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
> Cc: Stafford Horne <shorne@gmail.com>
> Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
> Cc: Rich Felker <dalias@libc.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Josh Triplett <josh@joshtriplett.org>
> Cc: Conor Dooley <conor@kernel.org>
> Cc: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: <linux-arm-kernel@lists.infradead.org>
> Cc: <linux-omap@vger.kernel.org>
> Cc: <openrisc@lists.librecores.org>
> Cc: <linux-riscv@lists.infradead.org>
> Cc: <linux-sh@vger.kernel.org>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: Roman Gushchin <roman.gushchin@linux.dev>

Thanks!