Commit e240e53a authored by Vlastimil Babka's avatar Vlastimil Babka
Browse files

mm, slub: add CONFIG_SLUB_TINY 



For tiny systems that have used SLOB until now, SLUB might be
impractical due to its higher memory usage. To help with that, introduce
an option CONFIG_SLUB_TINY that modifies SLUB to use less memory.
This is done by sacrificing scalability, security and debugging
features, therefore not recommended for any system with more than 16MB
RAM.

This commit introduces the option and uses it to set other related
options in a way that reduces memory usage.

Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarHyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Reviewed-by: default avatarChristoph Lameter <cl@linux.com>
parent 346907ce

lib/Kconfig.kasan

+1 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ menuconfig KASAN 
		     (HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS)) && \

		    CC_HAS_WORKING_NOSANITIZE_ADDRESS) || \

		   HAVE_ARCH_KASAN_HW_TAGS

	depends on (SLUB && SYSFS) || (SLAB && !DEBUG_SLAB)

	depends on (SLUB && SYSFS && !SLUB_TINY) || (SLAB && !DEBUG_SLAB)

	select STACKDEPOT_ALWAYS_INIT

	help

	  Enables KASAN (Kernel Address Sanitizer) - a dynamic memory safety

mm/Kconfig

+17 −4
Original line number Diff line number Diff line
@@ -230,6 +230,19 @@ config SLOB 


endchoice



config SLUB_TINY

	bool "Configure SLUB for minimal memory footprint"

	depends on SLUB && EXPERT

	select SLAB_MERGE_DEFAULT

	help

	   Configures the SLUB allocator in a way to achieve minimal memory

	   footprint, sacrificing scalability, debugging and other features.

	   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.



	   If unsure, say N.



config SLAB_MERGE_DEFAULT

	bool "Allow slab caches to be merged"

	default y
@@ -247,7 +260,7 @@ config SLAB_MERGE_DEFAULT 


config SLAB_FREELIST_RANDOM

	bool "Randomize slab freelist"

	depends on SLAB || SLUB

	depends on SLAB || (SLUB && !SLUB_TINY)

	help

	  Randomizes the freelist order used on creating new pages. This

	  security feature reduces the predictability of the kernel slab
@@ -255,7 +268,7 @@ config SLAB_FREELIST_RANDOM 


config SLAB_FREELIST_HARDENED

	bool "Harden slab freelist metadata"

	depends on SLAB || SLUB

	depends on SLAB || (SLUB && !SLUB_TINY)

	help

	  Many kernel heap attacks try to target slab cache metadata and

	  other infrastructure. This options makes minor performance
@@ -267,7 +280,7 @@ config SLAB_FREELIST_HARDENED 
config SLUB_STATS

	default n

	bool "Enable SLUB performance statistics"

	depends on SLUB && SYSFS

	depends on SLUB && SYSFS && !SLUB_TINY

	help

	  SLUB statistics are useful to debug SLUBs allocation behavior in

	  order find ways to optimize the allocator. This should never be
@@ -279,7 +292,7 @@ config SLUB_STATS 


config SLUB_CPU_PARTIAL

	default y

	depends on SLUB && SMP

	depends on SLUB && SMP && !SLUB_TINY

	bool "SLUB per cpu partial cache"

	help

	  Per cpu partial caches accelerate objects allocation and freeing

mm/Kconfig.debug

+1 −1
Original line number Diff line number Diff line
@@ -56,7 +56,7 @@ config DEBUG_SLAB 
config SLUB_DEBUG

	default y

	bool "Enable SLUB debugging support" if EXPERT

	depends on SLUB && SYSFS

	depends on SLUB && SYSFS && !SLUB_TINY

	select STACKDEPOT if STACKTRACE_SUPPORT

	help

	  SLUB has extensive debug support features. Disabling these can