mm: Kconfig: move swap and slab config options to the MM section
These are currently under General Setup. MM seems like a better fit. Link: https://lkml.kernel.org/r/20220510152847.230957-3-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Roman Gushchin <guro@fb.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Johannes Weiner
akpm
parent
39799b6409
commit
7b42f1041c
123
init/Kconfig
123
init/Kconfig
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@ -352,23 +352,6 @@ config DEFAULT_HOSTNAME
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but you may wish to use a different default here to make a minimal
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system more usable with less configuration.
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#
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# For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
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# add proper SWAP support to them, in which case this can be remove.
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#
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config ARCH_NO_SWAP
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bool
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config SWAP
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bool "Support for paging of anonymous memory (swap)"
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depends on MMU && BLOCK && !ARCH_NO_SWAP
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default y
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help
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This option allows you to choose whether you want to have support
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for so called swap devices or swap files in your kernel that are
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used to provide more virtual memory than the actual RAM present
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in your computer. If unsure say Y.
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config SYSVIPC
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bool "System V IPC"
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help
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@ -1876,112 +1859,6 @@ config COMPAT_BRK
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On non-ancient distros (post-2000 ones) N is usually a safe choice.
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choice
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prompt "Choose SLAB allocator"
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default SLUB
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help
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This option allows to select a slab allocator.
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config SLAB
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bool "SLAB"
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depends on !PREEMPT_RT
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select HAVE_HARDENED_USERCOPY_ALLOCATOR
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help
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The regular slab allocator that is established and known to work
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well in all environments. It organizes cache hot objects in
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per cpu and per node queues.
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config SLUB
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bool "SLUB (Unqueued Allocator)"
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select HAVE_HARDENED_USERCOPY_ALLOCATOR
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help
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SLUB is a slab allocator that minimizes cache line usage
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instead of managing queues of cached objects (SLAB approach).
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Per cpu caching is realized using slabs of objects instead
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of queues of objects. SLUB can use memory efficiently
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and has enhanced diagnostics. SLUB is the default choice for
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a slab allocator.
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config SLOB
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depends on EXPERT
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bool "SLOB (Simple Allocator)"
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depends on !PREEMPT_RT
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help
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SLOB replaces the stock allocator with a drastically simpler
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allocator. SLOB is generally more space efficient but
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does not perform as well on large systems.
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endchoice
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config SLAB_MERGE_DEFAULT
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bool "Allow slab caches to be merged"
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default y
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depends on SLAB || SLUB
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help
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For reduced kernel memory fragmentation, slab caches can be
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merged when they share the same size and other characteristics.
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This carries a risk of kernel heap overflows being able to
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overwrite objects from merged caches (and more easily control
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cache layout), which makes such heap attacks easier to exploit
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by attackers. By keeping caches unmerged, these kinds of exploits
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can usually only damage objects in the same cache. To disable
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merging at runtime, "slab_nomerge" can be passed on the kernel
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command line.
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config SLAB_FREELIST_RANDOM
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bool "Randomize slab freelist"
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depends on SLAB || SLUB
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help
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Randomizes the freelist order used on creating new pages. This
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security feature reduces the predictability of the kernel slab
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allocator against heap overflows.
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config SLAB_FREELIST_HARDENED
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bool "Harden slab freelist metadata"
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depends on SLAB || SLUB
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help
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Many kernel heap attacks try to target slab cache metadata and
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other infrastructure. This options makes minor performance
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sacrifices to harden the kernel slab allocator against common
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freelist exploit methods. Some slab implementations have more
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sanity-checking than others. This option is most effective with
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CONFIG_SLUB.
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config SHUFFLE_PAGE_ALLOCATOR
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bool "Page allocator randomization"
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default SLAB_FREELIST_RANDOM && ACPI_NUMA
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help
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Randomization of the page allocator improves the average
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utilization of a direct-mapped memory-side-cache. See section
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5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
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6.2a specification for an example of how a platform advertises
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the presence of a memory-side-cache. There are also incidental
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security benefits as it reduces the predictability of page
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allocations to compliment SLAB_FREELIST_RANDOM, but the
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default granularity of shuffling on the "MAX_ORDER - 1" i.e,
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10th order of pages is selected based on cache utilization
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benefits on x86.
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While the randomization improves cache utilization it may
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negatively impact workloads on platforms without a cache. For
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this reason, by default, the randomization is enabled only
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after runtime detection of a direct-mapped memory-side-cache.
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Otherwise, the randomization may be force enabled with the
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'page_alloc.shuffle' kernel command line parameter.
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Say Y if unsure.
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config SLUB_CPU_PARTIAL
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default y
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depends on SLUB && SMP
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bool "SLUB per cpu partial cache"
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help
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Per cpu partial caches accelerate objects allocation and freeing
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that is local to a processor at the price of more indeterminism
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in the latency of the free. On overflow these caches will be cleared
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which requires the taking of locks that may cause latency spikes.
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Typically one would choose no for a realtime system.
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config MMAP_ALLOW_UNINITIALIZED
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bool "Allow mmapped anonymous memory to be uninitialized"
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depends on EXPERT && !MMU
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123
mm/Kconfig
123
mm/Kconfig
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@ -2,6 +2,129 @@
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menu "Memory Management options"
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#
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# For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
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# add proper SWAP support to them, in which case this can be remove.
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#
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config ARCH_NO_SWAP
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bool
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config SWAP
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bool "Support for paging of anonymous memory (swap)"
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depends on MMU && BLOCK && !ARCH_NO_SWAP
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default y
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help
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This option allows you to choose whether you want to have support
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for so called swap devices or swap files in your kernel that are
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used to provide more virtual memory than the actual RAM present
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in your computer. If unsure say Y.
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choice
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prompt "Choose SLAB allocator"
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default SLUB
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help
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This option allows to select a slab allocator.
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config SLAB
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bool "SLAB"
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depends on !PREEMPT_RT
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select HAVE_HARDENED_USERCOPY_ALLOCATOR
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help
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The regular slab allocator that is established and known to work
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well in all environments. It organizes cache hot objects in
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per cpu and per node queues.
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config SLUB
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bool "SLUB (Unqueued Allocator)"
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select HAVE_HARDENED_USERCOPY_ALLOCATOR
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help
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SLUB is a slab allocator that minimizes cache line usage
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instead of managing queues of cached objects (SLAB approach).
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Per cpu caching is realized using slabs of objects instead
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of queues of objects. SLUB can use memory efficiently
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and has enhanced diagnostics. SLUB is the default choice for
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a slab allocator.
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config SLOB
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depends on EXPERT
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bool "SLOB (Simple Allocator)"
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depends on !PREEMPT_RT
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help
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SLOB replaces the stock allocator with a drastically simpler
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allocator. SLOB is generally more space efficient but
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does not perform as well on large systems.
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endchoice
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config SLAB_MERGE_DEFAULT
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bool "Allow slab caches to be merged"
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default y
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depends on SLAB || SLUB
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help
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For reduced kernel memory fragmentation, slab caches can be
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merged when they share the same size and other characteristics.
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This carries a risk of kernel heap overflows being able to
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overwrite objects from merged caches (and more easily control
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cache layout), which makes such heap attacks easier to exploit
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by attackers. By keeping caches unmerged, these kinds of exploits
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can usually only damage objects in the same cache. To disable
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merging at runtime, "slab_nomerge" can be passed on the kernel
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command line.
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config SLAB_FREELIST_RANDOM
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bool "Randomize slab freelist"
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depends on SLAB || SLUB
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help
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Randomizes the freelist order used on creating new pages. This
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security feature reduces the predictability of the kernel slab
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allocator against heap overflows.
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config SLAB_FREELIST_HARDENED
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bool "Harden slab freelist metadata"
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depends on SLAB || SLUB
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help
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Many kernel heap attacks try to target slab cache metadata and
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other infrastructure. This options makes minor performance
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sacrifices to harden the kernel slab allocator against common
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freelist exploit methods. Some slab implementations have more
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sanity-checking than others. This option is most effective with
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CONFIG_SLUB.
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config SHUFFLE_PAGE_ALLOCATOR
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bool "Page allocator randomization"
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default SLAB_FREELIST_RANDOM && ACPI_NUMA
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help
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Randomization of the page allocator improves the average
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utilization of a direct-mapped memory-side-cache. See section
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5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
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6.2a specification for an example of how a platform advertises
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the presence of a memory-side-cache. There are also incidental
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security benefits as it reduces the predictability of page
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allocations to compliment SLAB_FREELIST_RANDOM, but the
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default granularity of shuffling on the "MAX_ORDER - 1" i.e,
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10th order of pages is selected based on cache utilization
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benefits on x86.
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While the randomization improves cache utilization it may
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negatively impact workloads on platforms without a cache. For
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this reason, by default, the randomization is enabled only
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after runtime detection of a direct-mapped memory-side-cache.
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Otherwise, the randomization may be force enabled with the
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'page_alloc.shuffle' kernel command line parameter.
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Say Y if unsure.
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config SLUB_CPU_PARTIAL
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default y
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depends on SLUB && SMP
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bool "SLUB per cpu partial cache"
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help
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Per cpu partial caches accelerate objects allocation and freeing
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that is local to a processor at the price of more indeterminism
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in the latency of the free. On overflow these caches will be cleared
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which requires the taking of locks that may cause latency spikes.
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Typically one would choose no for a realtime system.
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config SELECT_MEMORY_MODEL
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def_bool y
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depends on ARCH_SELECT_MEMORY_MODEL
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