[PATCH 01/20] mm/slab: remove CONFIG_SLAB from all Kconfig and Makefile
From: Vlastimil Babka
Date: Mon Nov 13 2023 - 14:14:21 EST
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 as it's now always enabled.
Everything under #ifdef CONFIG_SLAB, and mm/slab.c is now dead code, all
code under #ifdef CONFIG_SLUB is now always compiled.
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
arch/arm64/Kconfig | 2 +-
arch/s390/Kconfig | 2 +-
arch/x86/Kconfig | 2 +-
lib/Kconfig.debug | 1 -
lib/Kconfig.kasan | 11 +++-------
lib/Kconfig.kfence | 2 +-
lib/Kconfig.kmsan | 2 +-
mm/Kconfig | 50 +++++++---------------------------------------
mm/Kconfig.debug | 16 ++++-----------
mm/Makefile | 6 +-----
10 files changed, 20 insertions(+), 74 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7b071a00425d..325b7140b576 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -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
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 3bec98d20283..afa42a6f2e09 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -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
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 3762f41bb092..3f460f334d4e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -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
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index cc7d53d9dc01..e1765face106 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -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.
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index fdca89c05745..97e1fdbb5910 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -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.
diff --git a/lib/Kconfig.kfence b/lib/Kconfig.kfence
index 459dda9ef619..6fbbebec683a 100644
--- a/lib/Kconfig.kfence
+++ b/lib/Kconfig.kfence
@@ -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
diff --git a/lib/Kconfig.kmsan b/lib/Kconfig.kmsan
index ef2c8f256c57..0541d7b079cc 100644
--- a/lib/Kconfig.kmsan
+++ b/lib/Kconfig.kmsan
@@ -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
diff --git a/mm/Kconfig b/mm/Kconfig
index 89971a894b60..766aa8f8e553 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -228,47 +228,12 @@ config ZSMALLOC_CHAIN_SIZE
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@xxxxxxxxx
- 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.
-
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
+ depends on EXPERT
select SLAB_MERGE_DEFAULT
help
Configures the SLUB allocator in a way to achieve minimal memory
@@ -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
@@ -304,7 +268,7 @@ 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
@@ -316,7 +280,7 @@ config SLAB_FREELIST_HARDENED
config SLUB_STATS
default n
bool "Enable SLUB performance statistics"
- depends on SLUB && SYSFS && !SLUB_TINY
+ depends on 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
@@ -328,7 +292,7 @@ config SLUB_STATS
config SLUB_CPU_PARTIAL
default y
- depends on SLUB && SMP && !SLUB_TINY
+ depends on SMP && !SLUB_TINY
bool "SLUB per cpu partial cache"
help
Per cpu partial caches accelerate objects allocation and freeing
@@ -339,7 +303,7 @@ 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
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 018a5bd2f576..321ab379994f 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -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).
diff --git a/mm/Makefile b/mm/Makefile
index 33873c8aedb3..e4b5b75aaec9 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -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/
--
2.42.1