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mm, slub: add CONFIG_SLUB_TINY

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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: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
This commit is contained in:
Vlastimil Babka 2022-11-14 18:13:45 +01:00
parent 346907ceb9
commit e240e53ae0
3 changed files with 19 additions and 6 deletions
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2
lib/Kconfig.kasan
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@ -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

21
mm/Kconfig
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@ -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

2
mm/Kconfig.debug
View File

@ -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