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mm/slab: remove CONFIG_SLAB from all Kconfig and Makefile

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Remove CONFIG_SLAB, CONFIG_DEBUG_SLAB, CONFIG_SLAB_DEPRECATED and
everything in Kconfig files and mm/Makefile that depends on those. Since
SLUB is the only remaining allocator, remove the allocator choice, make
CONFIG_SLUB a "def_bool y" for now and remove all explicit dependencies
on SLUB or SLAB as it's now always enabled. Make every option's verbose
name and description refer to "the slab allocator" without refering to
the specific implementation. Do not rename the CONFIG_ option names yet.

Everything under #ifdef CONFIG_SLAB, and mm/slab.c is now dead code, all
code under #ifdef CONFIG_SLUB is now always compiled.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Tested-by: David Rientjes <rientjes@google.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Vlastimil Babka 2023-10-02 15:43:03 +02:00
parent 0445ee0004
commit 2a19be61a6
10 changed files with 28 additions and 84 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arm64/Kconfig
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@ -154,7 +154,7 @@ config ARM64
select HAVE_MOVE_PUD
select HAVE_PCI
select HAVE_ACPI_APEI if (ACPI && EFI)
select HAVE_ALIGNED_STRUCT_PAGE if SLUB
select HAVE_ALIGNED_STRUCT_PAGE
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_BITREVERSE
select HAVE_ARCH_COMPILER_H

2
arch/s390/Kconfig
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@ -146,7 +146,7 @@ config S390
select GENERIC_TIME_VSYSCALL
select GENERIC_VDSO_TIME_NS
select GENERIC_IOREMAP if PCI
select HAVE_ALIGNED_STRUCT_PAGE if SLUB
select HAVE_ALIGNED_STRUCT_PAGE
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_JUMP_LABEL_RELATIVE

2
arch/x86/Kconfig
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@ -169,7 +169,7 @@ config X86
select HAS_IOPORT
select HAVE_ACPI_APEI if ACPI
select HAVE_ACPI_APEI_NMI if ACPI
select HAVE_ALIGNED_STRUCT_PAGE if SLUB
select HAVE_ALIGNED_STRUCT_PAGE
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
select HAVE_ARCH_HUGE_VMALLOC if X86_64

1
lib/Kconfig.debug
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@ -1985,7 +1985,6 @@ config FAULT_INJECTION
config FAILSLAB
bool "Fault-injection capability for kmalloc"
depends on FAULT_INJECTION
depends on SLAB || SLUB
help
Provide fault-injection capability for kmalloc.

11
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 && !SLUB_TINY) || (SLAB && !DEBUG_SLAB)
depends on SYSFS && !SLUB_TINY
select STACKDEPOT_ALWAYS_INIT
help
Enables KASAN (Kernel Address Sanitizer) - a dynamic memory safety
@ -78,7 +78,7 @@ config KASAN_GENERIC
bool "Generic KASAN"
depends on HAVE_ARCH_KASAN && CC_HAS_KASAN_GENERIC
depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS
select SLUB_DEBUG if SLUB
select SLUB_DEBUG
select CONSTRUCTORS
help
Enables Generic KASAN.
@ -89,13 +89,11 @@ config KASAN_GENERIC
overhead of ~50% for dynamic allocations.
The performance slowdown is ~x3.
(Incompatible with CONFIG_DEBUG_SLAB: the kernel does not boot.)
config KASAN_SW_TAGS
bool "Software Tag-Based KASAN"
depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS
depends on CC_HAS_WORKING_NOSANITIZE_ADDRESS
select SLUB_DEBUG if SLUB
select SLUB_DEBUG
select CONSTRUCTORS
help
Enables Software Tag-Based KASAN.
@ -110,12 +108,9 @@ config KASAN_SW_TAGS
May potentially introduce problems related to pointer casting and
comparison, as it embeds a tag into the top byte of each pointer.
(Incompatible with CONFIG_DEBUG_SLAB: the kernel does not boot.)
config KASAN_HW_TAGS
bool "Hardware Tag-Based KASAN"
depends on HAVE_ARCH_KASAN_HW_TAGS
depends on SLUB
help
Enables Hardware Tag-Based KASAN.

2
lib/Kconfig.kfence
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@ -5,7 +5,7 @@ config HAVE_ARCH_KFENCE
menuconfig KFENCE
bool "KFENCE: low-overhead sampling-based memory safety error detector"
depends on HAVE_ARCH_KFENCE && (SLAB || SLUB)
depends on HAVE_ARCH_KFENCE
select STACKTRACE
select IRQ_WORK
help

2
lib/Kconfig.kmsan
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@ -11,7 +11,7 @@ config HAVE_KMSAN_COMPILER
config KMSAN
bool "KMSAN: detector of uninitialized values use"
depends on HAVE_ARCH_KMSAN && HAVE_KMSAN_COMPILER
depends on SLUB && DEBUG_KERNEL && !KASAN && !KCSAN
depends on DEBUG_KERNEL && !KASAN && !KCSAN
depends on !PREEMPT_RT
select STACKDEPOT
select STACKDEPOT_ALWAYS_INIT

68
mm/Kconfig
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@ -226,52 +226,17 @@ config ZSMALLOC_CHAIN_SIZE
For more information, see zsmalloc documentation.
menu "SLAB allocator options"
choice
prompt "Choose SLAB allocator"
default SLUB
help
This option allows to select a slab allocator.
config SLAB_DEPRECATED
bool "SLAB (DEPRECATED)"
depends on !PREEMPT_RT
help
Deprecated and scheduled for removal in a few cycles. Replaced by
SLUB.
If you cannot migrate to SLUB, please contact linux-mm@kvack.org
and the people listed in the SLAB ALLOCATOR section of MAINTAINERS
file, explaining why.
The regular slab allocator that is established and known to work
well in all environments. It organizes cache hot objects in
per cpu and per node queues.
menu "Slab allocator options"
config SLUB
bool "SLUB (Unqueued Allocator)"
help
SLUB is a slab allocator that minimizes cache line usage
instead of managing queues of cached objects (SLAB approach).
Per cpu caching is realized using slabs of objects instead
of queues of objects. SLUB can use memory efficiently
and has enhanced diagnostics. SLUB is the default choice for
a slab allocator.
endchoice
config SLAB
bool
default y
depends on SLAB_DEPRECATED
def_bool y
config SLUB_TINY
bool "Configure SLUB for minimal memory footprint"
depends on SLUB && EXPERT
bool "Configure for minimal memory footprint"
depends on EXPERT
select SLAB_MERGE_DEFAULT
help
Configures the SLUB allocator in a way to achieve minimal memory
Configures the slab 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
@ -282,7 +247,6 @@ config SLUB_TINY
config SLAB_MERGE_DEFAULT
bool "Allow slab caches to be merged"
default y
depends on SLAB || SLUB
help
For reduced kernel memory fragmentation, slab caches can be
merged when they share the same size and other characteristics.
@ -296,7 +260,7 @@ config SLAB_MERGE_DEFAULT
config SLAB_FREELIST_RANDOM
bool "Randomize slab freelist"
depends on SLAB || (SLUB && !SLUB_TINY)
depends on !SLUB_TINY
help
Randomizes the freelist order used on creating new pages. This
security feature reduces the predictability of the kernel slab
@ -304,21 +268,19 @@ config SLAB_FREELIST_RANDOM
config SLAB_FREELIST_HARDENED
bool "Harden slab freelist metadata"
depends on SLAB || (SLUB && !SLUB_TINY)
depends on !SLUB_TINY
help
Many kernel heap attacks try to target slab cache metadata and
other infrastructure. This options makes minor performance
sacrifices to harden the kernel slab allocator against common
freelist exploit methods. Some slab implementations have more
sanity-checking than others. This option is most effective with
CONFIG_SLUB.
freelist exploit methods.
config SLUB_STATS
default n
bool "Enable SLUB performance statistics"
depends on SLUB && SYSFS && !SLUB_TINY
bool "Enable performance statistics"
depends on SYSFS && !SLUB_TINY
help
SLUB statistics are useful to debug SLUBs allocation behavior in
The statistics are useful to debug slab allocation behavior in
order find ways to optimize the allocator. This should never be
enabled for production use since keeping statistics slows down
the allocator by a few percentage points. The slabinfo command
@ -328,8 +290,8 @@ config SLUB_STATS
config SLUB_CPU_PARTIAL
default y
depends on SLUB && SMP && !SLUB_TINY
bool "SLUB per cpu partial cache"
depends on SMP && !SLUB_TINY
bool "Enable per cpu partial caches"
help
Per cpu partial caches accelerate objects allocation and freeing
that is local to a processor at the price of more indeterminism
@ -339,7 +301,7 @@ config SLUB_CPU_PARTIAL
config RANDOM_KMALLOC_CACHES
default n
depends on SLUB && !SLUB_TINY
depends on !SLUB_TINY
bool "Randomize slab caches for normal kmalloc"
help
A hardening feature that creates multiple copies of slab caches for
@ -354,7 +316,7 @@ config RANDOM_KMALLOC_CACHES
limited degree of memory and CPU overhead that relates to hardware and
system workload.
endmenu # SLAB allocator options
endmenu # Slab allocator options
config SHUFFLE_PAGE_ALLOCATOR
bool "Page allocator randomization"

16
mm/Kconfig.debug
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@ -45,18 +45,10 @@ config DEBUG_PAGEALLOC_ENABLE_DEFAULT
Enable debug page memory allocations by default? This value
can be overridden by debug_pagealloc=off|on.
config DEBUG_SLAB
bool "Debug slab memory allocations"
depends on DEBUG_KERNEL && SLAB
help
Say Y here to have the kernel do limited verification on memory
allocation as well as poisoning memory on free to catch use of freed
memory. This can make kmalloc/kfree-intensive workloads much slower.
config SLUB_DEBUG
default y
bool "Enable SLUB debugging support" if EXPERT
depends on SLUB && SYSFS && !SLUB_TINY
depends on SYSFS && !SLUB_TINY
select STACKDEPOT if STACKTRACE_SUPPORT
help
SLUB has extensive debug support features. Disabling these can
@ -66,7 +58,7 @@ config SLUB_DEBUG
config SLUB_DEBUG_ON
bool "SLUB debugging on by default"
depends on SLUB && SLUB_DEBUG
depends on SLUB_DEBUG
select STACKDEPOT_ALWAYS_INIT if STACKTRACE_SUPPORT
default n
help
@ -231,8 +223,8 @@ config DEBUG_KMEMLEAK
allocations. See Documentation/dev-tools/kmemleak.rst for more
details.
Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
of finding leaks due to the slab objects poisoning.
Enabling SLUB_DEBUG may increase the chances of finding leaks
due to the slab objects poisoning.
In order to access the kmemleak file, debugfs needs to be
mounted (usually at /sys/kernel/debug).

6
mm/Makefile
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@ -4,7 +4,6 @@
#
KASAN_SANITIZE_slab_common.o := n
KASAN_SANITIZE_slab.o := n
KASAN_SANITIZE_slub.o := n
KCSAN_SANITIZE_kmemleak.o := n
@ -12,7 +11,6 @@ KCSAN_SANITIZE_kmemleak.o := n
# the same word but accesses to different bits of that word. Re-enable KCSAN
# for these when we have more consensus on what to do about them.
KCSAN_SANITIZE_slab_common.o := n
KCSAN_SANITIZE_slab.o := n
KCSAN_SANITIZE_slub.o := n
KCSAN_SANITIZE_page_alloc.o := n
# But enable explicit instrumentation for memory barriers.
@ -22,7 +20,6 @@ KCSAN_INSTRUMENT_BARRIERS := y
# flaky coverage that is not a function of syscall inputs. E.g. slab is out of
# free pages, or a task is migrated between nodes.
KCOV_INSTRUMENT_slab_common.o := n
KCOV_INSTRUMENT_slab.o := n
KCOV_INSTRUMENT_slub.o := n
KCOV_INSTRUMENT_page_alloc.o := n
KCOV_INSTRUMENT_debug-pagealloc.o := n
@ -66,6 +63,7 @@ obj-y += page-alloc.o
obj-y += init-mm.o
obj-y += memblock.o
obj-y += $(memory-hotplug-y)
obj-y += slub.o
ifdef CONFIG_MMU
obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o
@ -82,8 +80,6 @@ obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
obj-$(CONFIG_KSM) += ksm.o
obj-$(CONFIG_PAGE_POISONING) += page_poison.o
obj-$(CONFIG_SLAB) += slab.o
obj-$(CONFIG_SLUB) += slub.o
obj-$(CONFIG_KASAN) += kasan/
obj-$(CONFIG_KFENCE) += kfence/
obj-$(CONFIG_KMSAN) += kmsan/