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Message-Id: <20231120-slab-remove-slab-v2-2-9c9c70177183@suse.cz> Date: Mon, 20 Nov 2023 19:34:13 +0100 From: Vlastimil Babka <vbabka@...e.cz> To: David Rientjes <rientjes@...gle.com>, Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>, Joonsoo Kim <iamjoonsoo.kim@....com> Cc: Andrew Morton <akpm@...ux-foundation.org>, Hyeonggon Yoo <42.hyeyoo@...il.com>, Roman Gushchin <roman.gushchin@...ux.dev>, Andrey Ryabinin <ryabinin.a.a@...il.com>, Alexander Potapenko <glider@...gle.com>, Andrey Konovalov <andreyknvl@...il.com>, Dmitry Vyukov <dvyukov@...gle.com>, Vincenzo Frascino <vincenzo.frascino@....com>, Marco Elver <elver@...gle.com>, Johannes Weiner <hannes@...xchg.org>, Michal Hocko <mhocko@...nel.org>, Shakeel Butt <shakeelb@...gle.com>, Muchun Song <muchun.song@...ux.dev>, Kees Cook <keescook@...omium.org>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com, cgroups@...r.kernel.org, linux-hardening@...r.kernel.org, Vlastimil Babka <vbabka@...e.cz> Subject: [PATCH v2 02/21] mm/slab: remove CONFIG_SLAB from all Kconfig and Makefile 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@...omium.org> Reviewed-by: Christoph Lameter <cl@...ux.com> Signed-off-by: Vlastimil Babka <vbabka@...e.cz> --- 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 | 68 ++++++++++++------------------------------------------ mm/Kconfig.debug | 16 ++++--------- mm/Makefile | 6 +---- 10 files changed, 28 insertions(+), 84 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..4636870499bb 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -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@...ck.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" 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
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