Re: [PATCH] mm/slab: rename CONFIG_SLAB to CONFIG_SLAB_DEPRECATED

From: David Rientjes <rientjes@google.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	 Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	 Roman Gushchin <roman.gushchin@linux.dev>,
	 Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	Shawn Guo <shawnguo@kernel.org>,
	 Sascha Hauer <s.hauer@pengutronix.de>,
	Vladimir Zapolskiy <vz@mleia.com>,  Andrew Lunn <andrew@lunn.ch>,
	 Gregory Clement <gregory.clement@bootlin.com>,
	 Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
	 Tony Lindgren <tony@atomide.com>, Qin Jian <qinjian@cqplus1.com>,
	 Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	 Dinh Nguyen <dinguyen@kernel.org>,
	 "James E . J . Bottomley"
	<James.Bottomley@hansenpartnership.com>,
	 Helge Deller <deller@gmx.de>,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	 Rich Felker <dalias@libc.org>,
	 John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
	 "David S . Miller" <davem@davemloft.net>,
	 Richard Weinberger <richard@nod.at>,
	 Anton Ivanov <anton.ivanov@cambridgegreys.com>,
	 Johannes Berg <johannes@sipsolutions.net>,
	 Andrew Morton <akpm@linux-foundation.org>,
	 linux-snps-arc@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	 linux-omap@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	 linux-tegra@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
	 linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
	 linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org,
	 sparclinux@vger.kernel.org, linux-um@lists.infradead.org,
	 linux-mm@kvack.org
Subject: Re: [PATCH] mm/slab: rename CONFIG_SLAB to CONFIG_SLAB_DEPRECATED
Date: Tue, 23 May 2023 17:29:17 -0700 (PDT)	[thread overview]
Message-ID: <be109b49-8510-5887-72ae-738db9945619@google.com> (raw)
In-Reply-To: <20230523091139.21449-1-vbabka@suse.cz>

On Tue, 23 May 2023, Vlastimil Babka wrote:

> As discussed at LSF/MM [1] [2] and with no objections raised there,
> deprecate the SLAB allocator. Rename the user-visible option so that
> users with CONFIG_SLAB=y get a new prompt with explanation during make
> oldconfig, while make olddefconfig will just switch to SLUB.
> 
> In all defconfigs with CONFIG_SLAB=y remove the line so those also
> switch to SLUB. Regressions due to the switch should be reported to
> linux-mm and slab maintainers.
> 
> [1] https://lore.kernel.org/all/4b9fc9c6-b48c-198f-5f80-811a44737e5f@suse.cz/
> [2] https://lwn.net/Articles/932201/
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: David Rientjes <rientjes@google.com>

The Kconfig option says that SLAB will be removed in a few cycles.  I 
think we should wait until at least the next LTS kernel is forked at the 
end of the year so that users who upgrade to only the LTS releases can be 
prompted for this change and surface any concerns.  Slab allocation is a 
critical subsystem, so I presume this is the safest and most responsible 
way to do the SLAB deprecation.  Hopefully that timeline works for 
everybody.