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b=n+3r7WjY0T01eAUCq/zRS0G+2hGEX5GFurChhcOIYE/HpDty0WA6gmzikNcxTYdH5 LhJWqrngg+qlGLVhYQimSpyue667XC+oTW6/Rxmbi6YLpG2amWpIW+41nxBiKRvPrG WJSCfxvpry0it2d4f/nZKPV/i9+7MudMWie7qr9DtEmLffMO7uj7+Gy1UolLzetOQ5 yyplSGcW1ofPrAArDLBpw0F9Rx4ZQN8TjkBWRG7FfXY5BZ2iJldfxNENi9M7Gr023V 3N0Fu1cYoper5E9v9Z1XiFPaLA9apxQwEo/s+bz3O9k1ymRsh+WlkQYoR8MNPndQ6/ ZbloiE7IXl+uQ== From: "Vlastimil Babka (SUSE)" Date: Sat, 24 Oct 2026 21:07:30 +0200 Subject: [PATCH RFC v2 8/8] mm, slab: deprecate CONFIG_SLUB_TINY and reduce its Kconfig effects X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261024-slub_tiny_rework-v2-8-bf1419ab5ffd@kernel.org> References: <20261024-slub_tiny_rework-v2-0-bf1419ab5ffd@kernel.org> In-Reply-To: <20261024-slub_tiny_rework-v2-0-bf1419ab5ffd@kernel.org> To: Harry Yoo Cc: Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Geert Uytterhoeven , Conor Dooley , Damien Le Moal , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Vlastimil Babka (SUSE)" X-Mailer: b4 0.16.0 X-Rspamd-Queue-Id: 6F94B40006 X-Stat-Signature: 4zzfz8ihf48gkgdp3ng69prd981nu5cx X-Rspamd-Server: rspam06 X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1792868877-427155 X-HE-Meta: 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 KGiNHqLv gZTstFYRMR24z7Uv22wLReJudPbPLR4HYRqho8m9Izv9+FaFK1jsNdLQLGTHp2+j85m2Ljuu/XPIVuf8RXtVry3YP4a9AC/vjUYbJ4o1hAygI49yiLp8+dQT7MPBlO5x7OsjGGA6n/5r/He6HQk1o3p0Q4sKVwZ3wn86vLNtQfO0757KoRBwRytol8bZgqrD95Dfajhes32+x37WtsMdKAAv28XBLpsHae2NnR12w96NHxxGD6V6b5teO9Fu5XTyNZQFAv2ojq3AVXg1N82swOLuWTsFfFsd2fVV4B9SLFUmMgbE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 At this point CONFIG_SLUB_TINY only affects the default value of slab_tiny_enabled which has a boot-time parameter. Thus deprecate it in the Kconfig description. Also remove its interactions with other Kconfig option, as they are not necessary: - KASAN, SLUB_DEBUG or SLUB_STATS support do not need !SLUB_TINY - KVFREE_RCU_BATCHED can simply depend on !TINY_RCU - various hardening options do not need to be excluded, although it's unlikely that somebody would enable those with extra memory overhead together with slab_tiny - SLAB_MERGE_DEFAULT does not need to be selected, although it's likely to be used together Keep the "depends on EXPERT && !COMPILE_TEST" as there's no point making the deprecated option more visible. Signed-off-by: Vlastimil Babka (SUSE) --- lib/Kconfig.kasan | 2 +- mm/Kconfig | 16 +++++++--------- mm/Kconfig.debug | 2 +- 3 files changed, 9 insertions(+), 11 deletions(-) diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index a4bb610a7a6f..f20b574f6653 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -49,7 +49,7 @@ menuconfig KASAN (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \ CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \ HAVE_ARCH_KASAN_HW_TAGS - depends on SYSFS && !SLUB_TINY + depends on SYSFS select STACKDEPOT_ALWAYS_INIT help Enables KASAN (Kernel Address Sanitizer) - a dynamic memory safety diff --git a/mm/Kconfig b/mm/Kconfig index edb4a6c0a870..2286073ea906 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -167,16 +167,18 @@ config SLUB config KVFREE_RCU_BATCHED def_bool y - depends on !SLUB_TINY && !TINY_RCU + depends on !TINY_RCU depends on !RCU_STRICT_GRACE_PERIOD config SLUB_TINY - bool "Configure for minimal memory footprint" + bool "Enable slab_tiny by default" depends on EXPERT && !COMPILE_TEST - select SLAB_MERGE_DEFAULT help + Deprecated option that enables the slab_tiny boot parameter by + default, and can be overridden by booting with slab_tiny=0. + Configures the slab allocator in a way to achieve minimal memory - footprint, sacrificing scalability, debugging and other features. + footprint, sacrificing scalability. This is intended only for the smallest system that had used the SLOB allocator and is not recommended for systems with more than 16MB RAM. @@ -199,7 +201,6 @@ config SLAB_MERGE_DEFAULT config SLAB_FREELIST_RANDOM bool "Randomize slab freelist" - depends on !SLUB_TINY help Randomizes the freelist order used on creating new pages. This security feature reduces the predictability of the kernel slab @@ -207,7 +208,6 @@ config SLAB_FREELIST_RANDOM config SLAB_FREELIST_HARDENED bool "Harden slab freelist metadata" - depends on !SLUB_TINY help Many kernel heap attacks try to target slab cache metadata and other infrastructure. This options makes minor performance @@ -216,7 +216,6 @@ config SLAB_FREELIST_HARDENED config SLAB_BUCKETS bool "Support allocation from separate kmalloc buckets" - depends on !SLUB_TINY default SLAB_FREELIST_HARDENED help Kernel heap attacks frequently depend on being able to create @@ -234,7 +233,7 @@ config SLAB_BUCKETS config SLUB_STATS default n bool "Enable performance statistics" - depends on SYSFS && !SLUB_TINY + depends on SYSFS help The statistics are useful to debug slab allocation behavior in order find ways to optimize the allocator. This should never be @@ -245,7 +244,6 @@ config SLUB_STATS Try running: slabinfo -DA config KMALLOC_PARTITION_CACHES - depends on !SLUB_TINY bool "Partitioned slab caches for normal kmalloc" default RANDOM_KMALLOC_CACHES help diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 9eaa25d1cf23..4e36c7c63ef7 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -48,7 +48,7 @@ config DEBUG_PAGEALLOC_ENABLE_DEFAULT config SLUB_DEBUG default y bool "Enable SLUB debugging support" if EXPERT - depends on SYSFS && !SLUB_TINY + depends on SYSFS select STACKDEPOT if STACKTRACE_SUPPORT help SLUB has extensive debug support features. Disabling these can -- 2.56.0