1# SPDX-License-Identifier: GPL-2.0-only
   2
   3menu "Memory Management options"
   4
   5#
   6# For some reason microblaze and nios2 hard code SWAP=n.  Hopefully we can
   7# add proper SWAP support to them, in which case this can be remove.
   8#
   9config ARCH_NO_SWAP
  10	bool
  11
  12config ZPOOL
  13	bool
  14
  15menuconfig SWAP
  16	bool "Support for paging of anonymous memory (swap)"
  17	depends on MMU && BLOCK && !ARCH_NO_SWAP
  18	default y
  19	help
  20	  This option allows you to choose whether you want to have support
  21	  for so called swap devices or swap files in your kernel that are
  22	  used to provide more virtual memory than the actual RAM present
  23	  in your computer.  If unsure say Y.
  24
  25config ZSWAP
  26	bool "Compressed cache for swap pages"
  27	depends on SWAP
  28	select CRYPTO
  29	select ZPOOL
  30	help
  31	  A lightweight compressed cache for swap pages.  It takes
  32	  pages that are in the process of being swapped out and attempts to
  33	  compress them into a dynamically allocated RAM-based memory pool.
  34	  This can result in a significant I/O reduction on swap device and,
  35	  in the case where decompressing from RAM is faster than swap device
  36	  reads, can also improve workload performance.
  37
  38config ZSWAP_DEFAULT_ON
  39	bool "Enable the compressed cache for swap pages by default"
  40	depends on ZSWAP
  41	help
  42	  If selected, the compressed cache for swap pages will be enabled
  43	  at boot, otherwise it will be disabled.
  44
  45	  The selection made here can be overridden by using the kernel
  46	  command line 'zswap.enabled=' option.
  47
  48config ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON
  49	bool "Invalidate zswap entries when pages are loaded"
  50	depends on ZSWAP
  51	help
  52	  If selected, exclusive loads for zswap will be enabled at boot,
  53	  otherwise it will be disabled.
  54
  55	  If exclusive loads are enabled, when a page is loaded from zswap,
  56	  the zswap entry is invalidated at once, as opposed to leaving it
  57	  in zswap until the swap entry is freed.
  58
  59	  This avoids having two copies of the same page in memory
  60	  (compressed and uncompressed) after faulting in a page from zswap.
  61	  The cost is that if the page was never dirtied and needs to be
  62	  swapped out again, it will be re-compressed.
  63
  64config ZSWAP_SHRINKER_DEFAULT_ON
  65	bool "Shrink the zswap pool on memory pressure"
  66	depends on ZSWAP
  67	default n
  68	help
  69	  If selected, the zswap shrinker will be enabled, and the pages
  70	  stored in the zswap pool will become available for reclaim (i.e
  71	  written back to the backing swap device) on memory pressure.
  72
  73	  This means that zswap writeback could happen even if the pool is
  74	  not yet full, or the cgroup zswap limit has not been reached,
  75	  reducing the chance that cold pages will reside in the zswap pool
  76	  and consume memory indefinitely.
  77
  78choice
  79	prompt "Default compressor"
  80	depends on ZSWAP
  81	default ZSWAP_COMPRESSOR_DEFAULT_LZO
  82	help
  83	  Selects the default compression algorithm for the compressed cache
  84	  for swap pages.
  85
  86	  For an overview what kind of performance can be expected from
  87	  a particular compression algorithm please refer to the benchmarks
  88	  available at the following LWN page:
  89	  https://lwn.net/Articles/751795/
  90
  91	  If in doubt, select 'LZO'.
  92
  93	  The selection made here can be overridden by using the kernel
  94	  command line 'zswap.compressor=' option.
  95
  96config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
  97	bool "Deflate"
  98	select CRYPTO_DEFLATE
  99	help
 100	  Use the Deflate algorithm as the default compression algorithm.
 101
 102config ZSWAP_COMPRESSOR_DEFAULT_LZO
 103	bool "LZO"
 104	select CRYPTO_LZO
 105	help
 106	  Use the LZO algorithm as the default compression algorithm.
 107
 108config ZSWAP_COMPRESSOR_DEFAULT_842
 109	bool "842"
 110	select CRYPTO_842
 111	help
 112	  Use the 842 algorithm as the default compression algorithm.
 113
 114config ZSWAP_COMPRESSOR_DEFAULT_LZ4
 115	bool "LZ4"
 116	select CRYPTO_LZ4
 117	help
 118	  Use the LZ4 algorithm as the default compression algorithm.
 119
 120config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
 121	bool "LZ4HC"
 122	select CRYPTO_LZ4HC
 123	help
 124	  Use the LZ4HC algorithm as the default compression algorithm.
 125
 126config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
 127	bool "zstd"
 128	select CRYPTO_ZSTD
 129	help
 130	  Use the zstd algorithm as the default compression algorithm.
 131endchoice
 132
 133config ZSWAP_COMPRESSOR_DEFAULT
 134       string
 135       depends on ZSWAP
 136       default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
 137       default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO
 138       default "842" if ZSWAP_COMPRESSOR_DEFAULT_842
 139       default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4
 140       default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
 141       default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
 142       default ""
 143
 144choice
 145	prompt "Default allocator"
 146	depends on ZSWAP
 147	default ZSWAP_ZPOOL_DEFAULT_ZSMALLOC if MMU
 148	default ZSWAP_ZPOOL_DEFAULT_ZBUD
 149	help
 150	  Selects the default allocator for the compressed cache for
 151	  swap pages.
 152	  The default is 'zbud' for compatibility, however please do
 153	  read the description of each of the allocators below before
 154	  making a right choice.
 155
 156	  The selection made here can be overridden by using the kernel
 157	  command line 'zswap.zpool=' option.
 158
 159config ZSWAP_ZPOOL_DEFAULT_ZBUD
 160	bool "zbud"
 161	select ZBUD
 162	help
 163	  Use the zbud allocator as the default allocator.
 164
 165config ZSWAP_ZPOOL_DEFAULT_Z3FOLD
 166	bool "z3fold"
 167	select Z3FOLD
 168	help
 169	  Use the z3fold allocator as the default allocator.
 170
 
 
 
 171config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
 172	bool "zsmalloc"
 173	select ZSMALLOC
 174	help
 175	  Use the zsmalloc allocator as the default allocator.
 176endchoice
 177
 178config ZSWAP_ZPOOL_DEFAULT
 179       string
 180       depends on ZSWAP
 181       default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
 182       default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD
 183       default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
 184       default ""
 185
 186config ZBUD
 187	tristate "2:1 compression allocator (zbud)"
 188	depends on ZSWAP
 189	help
 190	  A special purpose allocator for storing compressed pages.
 191	  It is designed to store up to two compressed pages per physical
 192	  page.  While this design limits storage density, it has simple and
 193	  deterministic reclaim properties that make it preferable to a higher
 194	  density approach when reclaim will be used.
 195
 196config Z3FOLD
 197	tristate "3:1 compression allocator (z3fold)"
 198	depends on ZSWAP
 199	help
 
 
 
 
 200	  A special purpose allocator for storing compressed pages.
 201	  It is designed to store up to three compressed pages per physical
 202	  page. It is a ZBUD derivative so the simplicity and determinism are
 203	  still there.
 204
 
 
 
 
 
 
 205config ZSMALLOC
 206	tristate
 207	prompt "N:1 compression allocator (zsmalloc)" if ZSWAP
 208	depends on MMU
 209	help
 210	  zsmalloc is a slab-based memory allocator designed to store
 211	  pages of various compression levels efficiently. It achieves
 212	  the highest storage density with the least amount of fragmentation.
 213
 214config ZSMALLOC_STAT
 215	bool "Export zsmalloc statistics"
 216	depends on ZSMALLOC
 217	select DEBUG_FS
 218	help
 219	  This option enables code in the zsmalloc to collect various
 220	  statistics about what's happening in zsmalloc and exports that
 221	  information to userspace via debugfs.
 222	  If unsure, say N.
 223
 224config ZSMALLOC_CHAIN_SIZE
 225	int "Maximum number of physical pages per-zspage"
 226	default 8
 227	range 4 16
 228	depends on ZSMALLOC
 229	help
 230	  This option sets the upper limit on the number of physical pages
 231	  that a zmalloc page (zspage) can consist of. The optimal zspage
 232	  chain size is calculated for each size class during the
 233	  initialization of the pool.
 234
 235	  Changing this option can alter the characteristics of size classes,
 236	  such as the number of pages per zspage and the number of objects
 237	  per zspage. This can also result in different configurations of
 238	  the pool, as zsmalloc merges size classes with similar
 239	  characteristics.
 240
 241	  For more information, see zsmalloc documentation.
 242
 243menu "Slab allocator options"
 244
 245config SLUB
 246	def_bool y
 247
 248config SLUB_TINY
 249	bool "Configure for minimal memory footprint"
 250	depends on EXPERT
 251	select SLAB_MERGE_DEFAULT
 252	help
 253	   Configures the slab allocator in a way to achieve minimal memory
 254	   footprint, sacrificing scalability, debugging and other features.
 255	   This is intended only for the smallest system that had used the
 256	   SLOB allocator and is not recommended for systems with more than
 257	   16MB RAM.
 258
 259	   If unsure, say N.
 260
 261config SLAB_MERGE_DEFAULT
 262	bool "Allow slab caches to be merged"
 263	default y
 264	help
 265	  For reduced kernel memory fragmentation, slab caches can be
 266	  merged when they share the same size and other characteristics.
 267	  This carries a risk of kernel heap overflows being able to
 268	  overwrite objects from merged caches (and more easily control
 269	  cache layout), which makes such heap attacks easier to exploit
 270	  by attackers. By keeping caches unmerged, these kinds of exploits
 271	  can usually only damage objects in the same cache. To disable
 272	  merging at runtime, "slab_nomerge" can be passed on the kernel
 273	  command line.
 274
 275config SLAB_FREELIST_RANDOM
 276	bool "Randomize slab freelist"
 277	depends on !SLUB_TINY
 278	help
 279	  Randomizes the freelist order used on creating new pages. This
 280	  security feature reduces the predictability of the kernel slab
 281	  allocator against heap overflows.
 282
 283config SLAB_FREELIST_HARDENED
 284	bool "Harden slab freelist metadata"
 285	depends on !SLUB_TINY
 286	help
 287	  Many kernel heap attacks try to target slab cache metadata and
 288	  other infrastructure. This options makes minor performance
 289	  sacrifices to harden the kernel slab allocator against common
 290	  freelist exploit methods.
 291
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 292config SLUB_STATS
 293	default n
 294	bool "Enable performance statistics"
 295	depends on SYSFS && !SLUB_TINY
 296	help
 297	  The statistics are useful to debug slab allocation behavior in
 298	  order find ways to optimize the allocator. This should never be
 299	  enabled for production use since keeping statistics slows down
 300	  the allocator by a few percentage points. The slabinfo command
 301	  supports the determination of the most active slabs to figure
 302	  out which slabs are relevant to a particular load.
 303	  Try running: slabinfo -DA
 304
 305config SLUB_CPU_PARTIAL
 306	default y
 307	depends on SMP && !SLUB_TINY
 308	bool "Enable per cpu partial caches"
 309	help
 310	  Per cpu partial caches accelerate objects allocation and freeing
 311	  that is local to a processor at the price of more indeterminism
 312	  in the latency of the free. On overflow these caches will be cleared
 313	  which requires the taking of locks that may cause latency spikes.
 314	  Typically one would choose no for a realtime system.
 315
 316config RANDOM_KMALLOC_CACHES
 317	default n
 318	depends on !SLUB_TINY
 319	bool "Randomize slab caches for normal kmalloc"
 320	help
 321	  A hardening feature that creates multiple copies of slab caches for
 322	  normal kmalloc allocation and makes kmalloc randomly pick one based
 323	  on code address, which makes the attackers more difficult to spray
 324	  vulnerable memory objects on the heap for the purpose of exploiting
 325	  memory vulnerabilities.
 326
 327	  Currently the number of copies is set to 16, a reasonably large value
 328	  that effectively diverges the memory objects allocated for different
 329	  subsystems or modules into different caches, at the expense of a
 330	  limited degree of memory and CPU overhead that relates to hardware and
 331	  system workload.
 332
 333endmenu # Slab allocator options
 334
 335config SHUFFLE_PAGE_ALLOCATOR
 336	bool "Page allocator randomization"
 337	default SLAB_FREELIST_RANDOM && ACPI_NUMA
 338	help
 339	  Randomization of the page allocator improves the average
 340	  utilization of a direct-mapped memory-side-cache. See section
 341	  5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
 342	  6.2a specification for an example of how a platform advertises
 343	  the presence of a memory-side-cache. There are also incidental
 344	  security benefits as it reduces the predictability of page
 345	  allocations to compliment SLAB_FREELIST_RANDOM, but the
 346	  default granularity of shuffling on the MAX_PAGE_ORDER i.e, 10th
 347	  order of pages is selected based on cache utilization benefits
 348	  on x86.
 349
 350	  While the randomization improves cache utilization it may
 351	  negatively impact workloads on platforms without a cache. For
 352	  this reason, by default, the randomization is enabled only
 353	  after runtime detection of a direct-mapped memory-side-cache.
 354	  Otherwise, the randomization may be force enabled with the
 355	  'page_alloc.shuffle' kernel command line parameter.
 356
 357	  Say Y if unsure.
 358
 359config COMPAT_BRK
 360	bool "Disable heap randomization"
 361	default y
 362	help
 363	  Randomizing heap placement makes heap exploits harder, but it
 364	  also breaks ancient binaries (including anything libc5 based).
 365	  This option changes the bootup default to heap randomization
 366	  disabled, and can be overridden at runtime by setting
 367	  /proc/sys/kernel/randomize_va_space to 2.
 368
 369	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
 370
 371config MMAP_ALLOW_UNINITIALIZED
 372	bool "Allow mmapped anonymous memory to be uninitialized"
 373	depends on EXPERT && !MMU
 374	default n
 375	help
 376	  Normally, and according to the Linux spec, anonymous memory obtained
 377	  from mmap() has its contents cleared before it is passed to
 378	  userspace.  Enabling this config option allows you to request that
 379	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
 380	  providing a huge performance boost.  If this option is not enabled,
 381	  then the flag will be ignored.
 382
 383	  This is taken advantage of by uClibc's malloc(), and also by
 384	  ELF-FDPIC binfmt's brk and stack allocator.
 385
 386	  Because of the obvious security issues, this option should only be
 387	  enabled on embedded devices where you control what is run in
 388	  userspace.  Since that isn't generally a problem on no-MMU systems,
 389	  it is normally safe to say Y here.
 390
 391	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
 392
 393config SELECT_MEMORY_MODEL
 394	def_bool y
 395	depends on ARCH_SELECT_MEMORY_MODEL
 396
 397choice
 398	prompt "Memory model"
 399	depends on SELECT_MEMORY_MODEL
 400	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
 401	default FLATMEM_MANUAL
 402	help
 403	  This option allows you to change some of the ways that
 404	  Linux manages its memory internally. Most users will
 405	  only have one option here selected by the architecture
 406	  configuration. This is normal.
 407
 408config FLATMEM_MANUAL
 409	bool "Flat Memory"
 410	depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
 411	help
 412	  This option is best suited for non-NUMA systems with
 413	  flat address space. The FLATMEM is the most efficient
 414	  system in terms of performance and resource consumption
 415	  and it is the best option for smaller systems.
 416
 417	  For systems that have holes in their physical address
 418	  spaces and for features like NUMA and memory hotplug,
 419	  choose "Sparse Memory".
 420
 421	  If unsure, choose this option (Flat Memory) over any other.
 422
 423config SPARSEMEM_MANUAL
 424	bool "Sparse Memory"
 425	depends on ARCH_SPARSEMEM_ENABLE
 426	help
 427	  This will be the only option for some systems, including
 428	  memory hot-plug systems.  This is normal.
 429
 430	  This option provides efficient support for systems with
 431	  holes is their physical address space and allows memory
 432	  hot-plug and hot-remove.
 433
 434	  If unsure, choose "Flat Memory" over this option.
 435
 436endchoice
 437
 438config SPARSEMEM
 439	def_bool y
 440	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
 441
 442config FLATMEM
 443	def_bool y
 444	depends on !SPARSEMEM || FLATMEM_MANUAL
 445
 446#
 447# SPARSEMEM_EXTREME (which is the default) does some bootmem
 448# allocations when sparse_init() is called.  If this cannot
 449# be done on your architecture, select this option.  However,
 450# statically allocating the mem_section[] array can potentially
 451# consume vast quantities of .bss, so be careful.
 452#
 453# This option will also potentially produce smaller runtime code
 454# with gcc 3.4 and later.
 455#
 456config SPARSEMEM_STATIC
 457	bool
 458
 459#
 460# Architecture platforms which require a two level mem_section in SPARSEMEM
 461# must select this option. This is usually for architecture platforms with
 462# an extremely sparse physical address space.
 463#
 464config SPARSEMEM_EXTREME
 465	def_bool y
 466	depends on SPARSEMEM && !SPARSEMEM_STATIC
 467
 468config SPARSEMEM_VMEMMAP_ENABLE
 469	bool
 470
 471config SPARSEMEM_VMEMMAP
 472	bool "Sparse Memory virtual memmap"
 473	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
 474	default y
 475	help
 476	  SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
 477	  pfn_to_page and page_to_pfn operations.  This is the most
 478	  efficient option when sufficient kernel resources are available.
 479#
 480# Select this config option from the architecture Kconfig, if it is preferred
 481# to enable the feature of HugeTLB/dev_dax vmemmap optimization.
 482#
 483config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
 484	bool
 485
 486config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
 487	bool
 488
 489config HAVE_MEMBLOCK_PHYS_MAP
 490	bool
 491
 492config HAVE_FAST_GUP
 493	depends on MMU
 494	bool
 495
 496# Don't discard allocated memory used to track "memory" and "reserved" memblocks
 497# after early boot, so it can still be used to test for validity of memory.
 498# Also, memblocks are updated with memory hot(un)plug.
 499config ARCH_KEEP_MEMBLOCK
 500	bool
 501
 502# Keep arch NUMA mapping infrastructure post-init.
 503config NUMA_KEEP_MEMINFO
 504	bool
 505
 506config MEMORY_ISOLATION
 507	bool
 508
 509# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
 510# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
 511# /dev/mem.
 512config EXCLUSIVE_SYSTEM_RAM
 513	def_bool y
 514	depends on !DEVMEM || STRICT_DEVMEM
 515
 516#
 517# Only be set on architectures that have completely implemented memory hotplug
 518# feature. If you are not sure, don't touch it.
 519#
 520config HAVE_BOOTMEM_INFO_NODE
 521	def_bool n
 522
 523config ARCH_ENABLE_MEMORY_HOTPLUG
 524	bool
 525
 526config ARCH_ENABLE_MEMORY_HOTREMOVE
 527	bool
 528
 529# eventually, we can have this option just 'select SPARSEMEM'
 530menuconfig MEMORY_HOTPLUG
 531	bool "Memory hotplug"
 532	select MEMORY_ISOLATION
 533	depends on SPARSEMEM
 534	depends on ARCH_ENABLE_MEMORY_HOTPLUG
 535	depends on 64BIT
 536	select NUMA_KEEP_MEMINFO if NUMA
 537
 538if MEMORY_HOTPLUG
 539
 540config MEMORY_HOTPLUG_DEFAULT_ONLINE
 541	bool "Online the newly added memory blocks by default"
 542	depends on MEMORY_HOTPLUG
 543	help
 544	  This option sets the default policy setting for memory hotplug
 545	  onlining policy (/sys/devices/system/memory/auto_online_blocks) which
 546	  determines what happens to newly added memory regions. Policy setting
 547	  can always be changed at runtime.
 548	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
 549
 550	  Say Y here if you want all hot-plugged memory blocks to appear in
 551	  'online' state by default.
 552	  Say N here if you want the default policy to keep all hot-plugged
 553	  memory blocks in 'offline' state.
 554
 555config MEMORY_HOTREMOVE
 556	bool "Allow for memory hot remove"
 557	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
 558	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
 559	depends on MIGRATION
 560
 561config MHP_MEMMAP_ON_MEMORY
 562	def_bool y
 563	depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP
 564	depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
 565
 566endif # MEMORY_HOTPLUG
 567
 568config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
 569       bool
 570
 571# Heavily threaded applications may benefit from splitting the mm-wide
 572# page_table_lock, so that faults on different parts of the user address
 573# space can be handled with less contention: split it at this NR_CPUS.
 574# Default to 4 for wider testing, though 8 might be more appropriate.
 575# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
 576# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
 577# SPARC32 allocates multiple pte tables within a single page, and therefore
 578# a per-page lock leads to problems when multiple tables need to be locked
 579# at the same time (e.g. copy_page_range()).
 580# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
 581#
 582config SPLIT_PTLOCK_CPUS
 583	int
 584	default "999999" if !MMU
 585	default "999999" if ARM && !CPU_CACHE_VIPT
 586	default "999999" if PARISC && !PA20
 587	default "999999" if SPARC32
 588	default "4"
 
 589
 590config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 591	bool
 592
 
 
 
 
 593#
 594# support for memory balloon
 595config MEMORY_BALLOON
 596	bool
 597
 598#
 599# support for memory balloon compaction
 600config BALLOON_COMPACTION
 601	bool "Allow for balloon memory compaction/migration"
 602	def_bool y
 603	depends on COMPACTION && MEMORY_BALLOON
 604	help
 605	  Memory fragmentation introduced by ballooning might reduce
 606	  significantly the number of 2MB contiguous memory blocks that can be
 607	  used within a guest, thus imposing performance penalties associated
 608	  with the reduced number of transparent huge pages that could be used
 609	  by the guest workload. Allowing the compaction & migration for memory
 610	  pages enlisted as being part of memory balloon devices avoids the
 611	  scenario aforementioned and helps improving memory defragmentation.
 612
 613#
 614# support for memory compaction
 615config COMPACTION
 616	bool "Allow for memory compaction"
 617	def_bool y
 618	select MIGRATION
 619	depends on MMU
 620	help
 621	  Compaction is the only memory management component to form
 622	  high order (larger physically contiguous) memory blocks
 623	  reliably. The page allocator relies on compaction heavily and
 624	  the lack of the feature can lead to unexpected OOM killer
 625	  invocations for high order memory requests. You shouldn't
 626	  disable this option unless there really is a strong reason for
 627	  it and then we would be really interested to hear about that at
 628	  linux-mm@kvack.org.
 629
 630config COMPACT_UNEVICTABLE_DEFAULT
 631	int
 632	depends on COMPACTION
 633	default 0 if PREEMPT_RT
 634	default 1
 635
 636#
 637# support for free page reporting
 638config PAGE_REPORTING
 639	bool "Free page reporting"
 640	def_bool n
 641	help
 642	  Free page reporting allows for the incremental acquisition of
 643	  free pages from the buddy allocator for the purpose of reporting
 644	  those pages to another entity, such as a hypervisor, so that the
 645	  memory can be freed within the host for other uses.
 646
 647#
 648# support for page migration
 649#
 650config MIGRATION
 651	bool "Page migration"
 652	def_bool y
 653	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
 654	help
 655	  Allows the migration of the physical location of pages of processes
 656	  while the virtual addresses are not changed. This is useful in
 657	  two situations. The first is on NUMA systems to put pages nearer
 658	  to the processors accessing. The second is when allocating huge
 659	  pages as migration can relocate pages to satisfy a huge page
 660	  allocation instead of reclaiming.
 661
 662config DEVICE_MIGRATION
 663	def_bool MIGRATION && ZONE_DEVICE
 664
 665config ARCH_ENABLE_HUGEPAGE_MIGRATION
 666	bool
 667
 668config ARCH_ENABLE_THP_MIGRATION
 669	bool
 670
 671config HUGETLB_PAGE_SIZE_VARIABLE
 672	def_bool n
 673	help
 674	  Allows the pageblock_order value to be dynamic instead of just standard
 675	  HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
 676	  on a platform.
 677
 678	  Note that the pageblock_order cannot exceed MAX_PAGE_ORDER and will be
 679	  clamped down to MAX_PAGE_ORDER.
 680
 681config CONTIG_ALLOC
 682	def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
 683
 684config PCP_BATCH_SCALE_MAX
 685	int "Maximum scale factor of PCP (Per-CPU pageset) batch allocate/free"
 686	default 5
 687	range 0 6
 688	help
 689	  In page allocator, PCP (Per-CPU pageset) is refilled and drained in
 690	  batches.  The batch number is scaled automatically to improve page
 691	  allocation/free throughput.  But too large scale factor may hurt
 692	  latency.  This option sets the upper limit of scale factor to limit
 693	  the maximum latency.
 694
 695config PHYS_ADDR_T_64BIT
 696	def_bool 64BIT
 697
 698config BOUNCE
 699	bool "Enable bounce buffers"
 700	default y
 701	depends on BLOCK && MMU && HIGHMEM
 702	help
 703	  Enable bounce buffers for devices that cannot access the full range of
 704	  memory available to the CPU. Enabled by default when HIGHMEM is
 705	  selected, but you may say n to override this.
 706
 707config MMU_NOTIFIER
 708	bool
 709	select INTERVAL_TREE
 710
 711config KSM
 712	bool "Enable KSM for page merging"
 713	depends on MMU
 714	select XXHASH
 715	help
 716	  Enable Kernel Samepage Merging: KSM periodically scans those areas
 717	  of an application's address space that an app has advised may be
 718	  mergeable.  When it finds pages of identical content, it replaces
 719	  the many instances by a single page with that content, so
 720	  saving memory until one or another app needs to modify the content.
 721	  Recommended for use with KVM, or with other duplicative applications.
 722	  See Documentation/mm/ksm.rst for more information: KSM is inactive
 723	  until a program has madvised that an area is MADV_MERGEABLE, and
 724	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
 725
 726config DEFAULT_MMAP_MIN_ADDR
 727	int "Low address space to protect from user allocation"
 728	depends on MMU
 729	default 4096
 730	help
 731	  This is the portion of low virtual memory which should be protected
 732	  from userspace allocation.  Keeping a user from writing to low pages
 733	  can help reduce the impact of kernel NULL pointer bugs.
 734
 735	  For most ppc64 and x86 users with lots of address space
 736	  a value of 65536 is reasonable and should cause no problems.
 737	  On arm and other archs it should not be higher than 32768.
 738	  Programs which use vm86 functionality or have some need to map
 739	  this low address space will need CAP_SYS_RAWIO or disable this
 740	  protection by setting the value to 0.
 741
 742	  This value can be changed after boot using the
 743	  /proc/sys/vm/mmap_min_addr tunable.
 744
 745config ARCH_SUPPORTS_MEMORY_FAILURE
 746	bool
 747
 748config MEMORY_FAILURE
 749	depends on MMU
 750	depends on ARCH_SUPPORTS_MEMORY_FAILURE
 751	bool "Enable recovery from hardware memory errors"
 752	select MEMORY_ISOLATION
 753	select RAS
 754	help
 755	  Enables code to recover from some memory failures on systems
 756	  with MCA recovery. This allows a system to continue running
 757	  even when some of its memory has uncorrected errors. This requires
 758	  special hardware support and typically ECC memory.
 759
 760config HWPOISON_INJECT
 761	tristate "HWPoison pages injector"
 762	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
 763	select PROC_PAGE_MONITOR
 764
 765config NOMMU_INITIAL_TRIM_EXCESS
 766	int "Turn on mmap() excess space trimming before booting"
 767	depends on !MMU
 768	default 1
 769	help
 770	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
 771	  of memory on which to store mappings, but it can only ask the system
 772	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
 773	  more than it requires.  To deal with this, mmap() is able to trim off
 774	  the excess and return it to the allocator.
 775
 776	  If trimming is enabled, the excess is trimmed off and returned to the
 777	  system allocator, which can cause extra fragmentation, particularly
 778	  if there are a lot of transient processes.
 779
 780	  If trimming is disabled, the excess is kept, but not used, which for
 781	  long-term mappings means that the space is wasted.
 782
 783	  Trimming can be dynamically controlled through a sysctl option
 784	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
 785	  excess pages there must be before trimming should occur, or zero if
 786	  no trimming is to occur.
 787
 788	  This option specifies the initial value of this option.  The default
 789	  of 1 says that all excess pages should be trimmed.
 790
 791	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
 792
 793config ARCH_WANT_GENERAL_HUGETLB
 794	bool
 795
 796config ARCH_WANTS_THP_SWAP
 797	def_bool n
 798
 799menuconfig TRANSPARENT_HUGEPAGE
 800	bool "Transparent Hugepage Support"
 801	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
 802	select COMPACTION
 803	select XARRAY_MULTI
 804	help
 805	  Transparent Hugepages allows the kernel to use huge pages and
 806	  huge tlb transparently to the applications whenever possible.
 807	  This feature can improve computing performance to certain
 808	  applications by speeding up page faults during memory
 809	  allocation, by reducing the number of tlb misses and by speeding
 810	  up the pagetable walking.
 811
 812	  If memory constrained on embedded, you may want to say N.
 813
 814if TRANSPARENT_HUGEPAGE
 815
 816choice
 817	prompt "Transparent Hugepage Support sysfs defaults"
 818	depends on TRANSPARENT_HUGEPAGE
 819	default TRANSPARENT_HUGEPAGE_ALWAYS
 820	help
 821	  Selects the sysfs defaults for Transparent Hugepage Support.
 822
 823	config TRANSPARENT_HUGEPAGE_ALWAYS
 824		bool "always"
 825	help
 826	  Enabling Transparent Hugepage always, can increase the
 827	  memory footprint of applications without a guaranteed
 828	  benefit but it will work automatically for all applications.
 829
 830	config TRANSPARENT_HUGEPAGE_MADVISE
 831		bool "madvise"
 832	help
 833	  Enabling Transparent Hugepage madvise, will only provide a
 834	  performance improvement benefit to the applications using
 835	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
 836	  memory footprint of applications without a guaranteed
 837	  benefit.
 838
 839	config TRANSPARENT_HUGEPAGE_NEVER
 840		bool "never"
 841	help
 842	  Disable Transparent Hugepage by default. It can still be
 843	  enabled at runtime via sysfs.
 844endchoice
 845
 846config THP_SWAP
 847	def_bool y
 848	depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT
 849	help
 850	  Swap transparent huge pages in one piece, without splitting.
 851	  XXX: For now, swap cluster backing transparent huge page
 852	  will be split after swapout.
 853
 854	  For selection by architectures with reasonable THP sizes.
 855
 856config READ_ONLY_THP_FOR_FS
 857	bool "Read-only THP for filesystems (EXPERIMENTAL)"
 858	depends on TRANSPARENT_HUGEPAGE && SHMEM
 859
 860	help
 861	  Allow khugepaged to put read-only file-backed pages in THP.
 862
 863	  This is marked experimental because it is a new feature. Write
 864	  support of file THPs will be developed in the next few release
 865	  cycles.
 866
 867endif # TRANSPARENT_HUGEPAGE
 868
 869#
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 870# UP and nommu archs use km based percpu allocator
 871#
 872config NEED_PER_CPU_KM
 873	depends on !SMP || !MMU
 874	bool
 875	default y
 876
 877config NEED_PER_CPU_EMBED_FIRST_CHUNK
 878	bool
 879
 880config NEED_PER_CPU_PAGE_FIRST_CHUNK
 881	bool
 882
 883config USE_PERCPU_NUMA_NODE_ID
 884	bool
 885
 886config HAVE_SETUP_PER_CPU_AREA
 887	bool
 888
 889config CMA
 890	bool "Contiguous Memory Allocator"
 891	depends on MMU
 892	select MIGRATION
 893	select MEMORY_ISOLATION
 894	help
 895	  This enables the Contiguous Memory Allocator which allows other
 896	  subsystems to allocate big physically-contiguous blocks of memory.
 897	  CMA reserves a region of memory and allows only movable pages to
 898	  be allocated from it. This way, the kernel can use the memory for
 899	  pagecache and when a subsystem requests for contiguous area, the
 900	  allocated pages are migrated away to serve the contiguous request.
 901
 902	  If unsure, say "n".
 903
 904config CMA_DEBUG
 905	bool "CMA debug messages (DEVELOPMENT)"
 906	depends on DEBUG_KERNEL && CMA
 907	help
 908	  Turns on debug messages in CMA.  This produces KERN_DEBUG
 909	  messages for every CMA call as well as various messages while
 910	  processing calls such as dma_alloc_from_contiguous().
 911	  This option does not affect warning and error messages.
 912
 913config CMA_DEBUGFS
 914	bool "CMA debugfs interface"
 915	depends on CMA && DEBUG_FS
 916	help
 917	  Turns on the DebugFS interface for CMA.
 918
 919config CMA_SYSFS
 920	bool "CMA information through sysfs interface"
 921	depends on CMA && SYSFS
 922	help
 923	  This option exposes some sysfs attributes to get information
 924	  from CMA.
 925
 926config CMA_AREAS
 927	int "Maximum count of the CMA areas"
 928	depends on CMA
 929	default 19 if NUMA
 930	default 7
 931	help
 932	  CMA allows to create CMA areas for particular purpose, mainly,
 933	  used as device private area. This parameter sets the maximum
 934	  number of CMA area in the system.
 935
 936	  If unsure, leave the default value "7" in UMA and "19" in NUMA.
 937
 938config MEM_SOFT_DIRTY
 939	bool "Track memory changes"
 940	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
 941	select PROC_PAGE_MONITOR
 942	help
 943	  This option enables memory changes tracking by introducing a
 944	  soft-dirty bit on pte-s. This bit it set when someone writes
 945	  into a page just as regular dirty bit, but unlike the latter
 946	  it can be cleared by hands.
 947
 948	  See Documentation/admin-guide/mm/soft-dirty.rst for more details.
 949
 950config GENERIC_EARLY_IOREMAP
 951	bool
 952
 953config STACK_MAX_DEFAULT_SIZE_MB
 954	int "Default maximum user stack size for 32-bit processes (MB)"
 955	default 100
 956	range 8 2048
 957	depends on STACK_GROWSUP && (!64BIT || COMPAT)
 958	help
 959	  This is the maximum stack size in Megabytes in the VM layout of 32-bit
 960	  user processes when the stack grows upwards (currently only on parisc
 961	  arch) when the RLIMIT_STACK hard limit is unlimited.
 962
 963	  A sane initial value is 100 MB.
 964
 965config DEFERRED_STRUCT_PAGE_INIT
 966	bool "Defer initialisation of struct pages to kthreads"
 967	depends on SPARSEMEM
 968	depends on !NEED_PER_CPU_KM
 969	depends on 64BIT
 
 970	select PADATA
 971	help
 972	  Ordinarily all struct pages are initialised during early boot in a
 973	  single thread. On very large machines this can take a considerable
 974	  amount of time. If this option is set, large machines will bring up
 975	  a subset of memmap at boot and then initialise the rest in parallel.
 976	  This has a potential performance impact on tasks running early in the
 977	  lifetime of the system until these kthreads finish the
 978	  initialisation.
 979
 980config PAGE_IDLE_FLAG
 981	bool
 982	select PAGE_EXTENSION if !64BIT
 983	help
 984	  This adds PG_idle and PG_young flags to 'struct page'.  PTE Accessed
 985	  bit writers can set the state of the bit in the flags so that PTE
 986	  Accessed bit readers may avoid disturbance.
 987
 988config IDLE_PAGE_TRACKING
 989	bool "Enable idle page tracking"
 990	depends on SYSFS && MMU
 991	select PAGE_IDLE_FLAG
 992	help
 993	  This feature allows to estimate the amount of user pages that have
 994	  not been touched during a given period of time. This information can
 995	  be useful to tune memory cgroup limits and/or for job placement
 996	  within a compute cluster.
 997
 998	  See Documentation/admin-guide/mm/idle_page_tracking.rst for
 999	  more details.
1000
 
 
 
 
 
 
1001config ARCH_HAS_CACHE_LINE_SIZE
1002	bool
1003
1004config ARCH_HAS_CURRENT_STACK_POINTER
1005	bool
1006	help
1007	  In support of HARDENED_USERCOPY performing stack variable lifetime
1008	  checking, an architecture-agnostic way to find the stack pointer
1009	  is needed. Once an architecture defines an unsigned long global
1010	  register alias named "current_stack_pointer", this config can be
1011	  selected.
1012
1013config ARCH_HAS_PTE_DEVMAP
1014	bool
1015
1016config ARCH_HAS_ZONE_DMA_SET
1017	bool
1018
1019config ZONE_DMA
1020	bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET
1021	default y if ARM64 || X86
1022
1023config ZONE_DMA32
1024	bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET
1025	depends on !X86_32
1026	default y if ARM64
1027
1028config ZONE_DEVICE
1029	bool "Device memory (pmem, HMM, etc...) hotplug support"
1030	depends on MEMORY_HOTPLUG
1031	depends on MEMORY_HOTREMOVE
1032	depends on SPARSEMEM_VMEMMAP
1033	depends on ARCH_HAS_PTE_DEVMAP
1034	select XARRAY_MULTI
1035
1036	help
1037	  Device memory hotplug support allows for establishing pmem,
1038	  or other device driver discovered memory regions, in the
1039	  memmap. This allows pfn_to_page() lookups of otherwise
1040	  "device-physical" addresses which is needed for using a DAX
1041	  mapping in an O_DIRECT operation, among other things.
1042
1043	  If FS_DAX is enabled, then say Y.
1044
1045#
1046# Helpers to mirror range of the CPU page tables of a process into device page
1047# tables.
1048#
1049config HMM_MIRROR
1050	bool
1051	depends on MMU
1052
1053config GET_FREE_REGION
1054	depends on SPARSEMEM
1055	bool
1056
1057config DEVICE_PRIVATE
1058	bool "Unaddressable device memory (GPU memory, ...)"
1059	depends on ZONE_DEVICE
1060	select GET_FREE_REGION
1061
1062	help
1063	  Allows creation of struct pages to represent unaddressable device
1064	  memory; i.e., memory that is only accessible from the device (or
1065	  group of devices). You likely also want to select HMM_MIRROR.
1066
1067config VMAP_PFN
1068	bool
1069
1070config ARCH_USES_HIGH_VMA_FLAGS
1071	bool
1072config ARCH_HAS_PKEYS
1073	bool
1074
1075config ARCH_USES_PG_ARCH_X
 
 
1076	bool
1077	help
1078	  Enable the definition of PG_arch_x page flags with x > 1. Only
1079	  suitable for 64-bit architectures with CONFIG_FLATMEM or
1080	  CONFIG_SPARSEMEM_VMEMMAP enabled, otherwise there may not be
1081	  enough room for additional bits in page->flags.
1082
1083config VM_EVENT_COUNTERS
1084	default y
1085	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1086	help
1087	  VM event counters are needed for event counts to be shown.
1088	  This option allows the disabling of the VM event counters
1089	  on EXPERT systems.  /proc/vmstat will only show page counts
1090	  if VM event counters are disabled.
1091
1092config PERCPU_STATS
1093	bool "Collect percpu memory statistics"
1094	help
1095	  This feature collects and exposes statistics via debugfs. The
1096	  information includes global and per chunk statistics, which can
1097	  be used to help understand percpu memory usage.
1098
1099config GUP_TEST
1100	bool "Enable infrastructure for get_user_pages()-related unit tests"
1101	depends on DEBUG_FS
1102	help
1103	  Provides /sys/kernel/debug/gup_test, which in turn provides a way
1104	  to make ioctl calls that can launch kernel-based unit tests for
1105	  the get_user_pages*() and pin_user_pages*() family of API calls.
1106
1107	  These tests include benchmark testing of the _fast variants of
1108	  get_user_pages*() and pin_user_pages*(), as well as smoke tests of
1109	  the non-_fast variants.
1110
1111	  There is also a sub-test that allows running dump_page() on any
1112	  of up to eight pages (selected by command line args) within the
1113	  range of user-space addresses. These pages are either pinned via
1114	  pin_user_pages*(), or pinned via get_user_pages*(), as specified
1115	  by other command line arguments.
1116
1117	  See tools/testing/selftests/mm/gup_test.c
1118
1119comment "GUP_TEST needs to have DEBUG_FS enabled"
1120	depends on !GUP_TEST && !DEBUG_FS
1121
1122config GUP_GET_PXX_LOW_HIGH
1123	bool
1124
1125config DMAPOOL_TEST
1126	tristate "Enable a module to run time tests on dma_pool"
1127	depends on HAS_DMA
1128	help
1129	  Provides a test module that will allocate and free many blocks of
1130	  various sizes and report how long it takes. This is intended to
1131	  provide a consistent way to measure how changes to the
1132	  dma_pool_alloc/free routines affect performance.
1133
1134config ARCH_HAS_PTE_SPECIAL
1135	bool
1136
1137#
1138# Some architectures require a special hugepage directory format that is
1139# required to support multiple hugepage sizes. For example a4fe3ce76
1140# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
1141# introduced it on powerpc.  This allows for a more flexible hugepage
1142# pagetable layouts.
1143#
1144config ARCH_HAS_HUGEPD
1145	bool
1146
1147config MAPPING_DIRTY_HELPERS
1148        bool
1149
1150config KMAP_LOCAL
1151	bool
1152
1153config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1154	bool
1155
1156# struct io_mapping based helper.  Selected by drivers that need them
1157config IO_MAPPING
1158	bool
1159
1160config MEMFD_CREATE
1161	bool "Enable memfd_create() system call" if EXPERT
1162
1163config SECRETMEM
1164	default y
1165	bool "Enable memfd_secret() system call" if EXPERT
1166	depends on ARCH_HAS_SET_DIRECT_MAP
1167	help
1168	  Enable the memfd_secret() system call with the ability to create
1169	  memory areas visible only in the context of the owning process and
1170	  not mapped to other processes and other kernel page tables.
1171
1172config ANON_VMA_NAME
1173	bool "Anonymous VMA name support"
1174	depends on PROC_FS && ADVISE_SYSCALLS && MMU
1175
1176	help
1177	  Allow naming anonymous virtual memory areas.
1178
1179	  This feature allows assigning names to virtual memory areas. Assigned
1180	  names can be later retrieved from /proc/pid/maps and /proc/pid/smaps
1181	  and help identifying individual anonymous memory areas.
1182	  Assigning a name to anonymous virtual memory area might prevent that
1183	  area from being merged with adjacent virtual memory areas due to the
1184	  difference in their name.
1185
1186config HAVE_ARCH_USERFAULTFD_WP
1187	bool
1188	help
1189	  Arch has userfaultfd write protection support
1190
1191config HAVE_ARCH_USERFAULTFD_MINOR
1192	bool
1193	help
1194	  Arch has userfaultfd minor fault support
1195
1196menuconfig USERFAULTFD
1197	bool "Enable userfaultfd() system call"
1198	depends on MMU
1199	help
1200	  Enable the userfaultfd() system call that allows to intercept and
1201	  handle page faults in userland.
1202
1203if USERFAULTFD
1204config PTE_MARKER_UFFD_WP
1205	bool "Userfaultfd write protection support for shmem/hugetlbfs"
1206	default y
1207	depends on HAVE_ARCH_USERFAULTFD_WP
1208
1209	help
1210	  Allows to create marker PTEs for userfaultfd write protection
1211	  purposes.  It is required to enable userfaultfd write protection on
1212	  file-backed memory types like shmem and hugetlbfs.
1213endif # USERFAULTFD
1214
1215# multi-gen LRU {
1216config LRU_GEN
1217	bool "Multi-Gen LRU"
1218	depends on MMU
1219	# make sure folio->flags has enough spare bits
1220	depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP
1221	help
1222	  A high performance LRU implementation to overcommit memory. See
1223	  Documentation/admin-guide/mm/multigen_lru.rst for details.
1224
1225config LRU_GEN_ENABLED
1226	bool "Enable by default"
1227	depends on LRU_GEN
1228	help
1229	  This option enables the multi-gen LRU by default.
1230
1231config LRU_GEN_STATS
1232	bool "Full stats for debugging"
1233	depends on LRU_GEN
1234	help
1235	  Do not enable this option unless you plan to look at historical stats
1236	  from evicted generations for debugging purpose.
1237
1238	  This option has a per-memcg and per-node memory overhead.
1239
1240config LRU_GEN_WALKS_MMU
1241	def_bool y
1242	depends on LRU_GEN && ARCH_HAS_HW_PTE_YOUNG
1243# }
1244
1245config ARCH_SUPPORTS_PER_VMA_LOCK
1246       def_bool n
1247
1248config PER_VMA_LOCK
1249	def_bool y
1250	depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP
1251	help
1252	  Allow per-vma locking during page fault handling.
1253
1254	  This feature allows locking each virtual memory area separately when
1255	  handling page faults instead of taking mmap_lock.
1256
1257config LOCK_MM_AND_FIND_VMA
1258	bool
1259	depends on !STACK_GROWSUP
1260
1261config IOMMU_MM_DATA
1262	bool
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1263
1264source "mm/damon/Kconfig"
1265
1266endmenu

   1# SPDX-License-Identifier: GPL-2.0-only
   2
   3menu "Memory Management options"
   4
   5#
   6# For some reason microblaze and nios2 hard code SWAP=n.  Hopefully we can
   7# add proper SWAP support to them, in which case this can be remove.
   8#
   9config ARCH_NO_SWAP
  10	bool
  11
  12config ZPOOL
  13	bool
  14
  15menuconfig SWAP
  16	bool "Support for paging of anonymous memory (swap)"
  17	depends on MMU && BLOCK && !ARCH_NO_SWAP
  18	default y
  19	help
  20	  This option allows you to choose whether you want to have support
  21	  for so called swap devices or swap files in your kernel that are
  22	  used to provide more virtual memory than the actual RAM present
  23	  in your computer.  If unsure say Y.
  24
  25config ZSWAP
  26	bool "Compressed cache for swap pages"
  27	depends on SWAP
  28	select CRYPTO
  29	select ZPOOL
  30	help
  31	  A lightweight compressed cache for swap pages.  It takes
  32	  pages that are in the process of being swapped out and attempts to
  33	  compress them into a dynamically allocated RAM-based memory pool.
  34	  This can result in a significant I/O reduction on swap device and,
  35	  in the case where decompressing from RAM is faster than swap device
  36	  reads, can also improve workload performance.
  37
  38config ZSWAP_DEFAULT_ON
  39	bool "Enable the compressed cache for swap pages by default"
  40	depends on ZSWAP
  41	help
  42	  If selected, the compressed cache for swap pages will be enabled
  43	  at boot, otherwise it will be disabled.
  44
  45	  The selection made here can be overridden by using the kernel
  46	  command line 'zswap.enabled=' option.
  47
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  48config ZSWAP_SHRINKER_DEFAULT_ON
  49	bool "Shrink the zswap pool on memory pressure"
  50	depends on ZSWAP
  51	default n
  52	help
  53	  If selected, the zswap shrinker will be enabled, and the pages
  54	  stored in the zswap pool will become available for reclaim (i.e
  55	  written back to the backing swap device) on memory pressure.
  56
  57	  This means that zswap writeback could happen even if the pool is
  58	  not yet full, or the cgroup zswap limit has not been reached,
  59	  reducing the chance that cold pages will reside in the zswap pool
  60	  and consume memory indefinitely.
  61
  62choice
  63	prompt "Default compressor"
  64	depends on ZSWAP
  65	default ZSWAP_COMPRESSOR_DEFAULT_LZO
  66	help
  67	  Selects the default compression algorithm for the compressed cache
  68	  for swap pages.
  69
  70	  For an overview what kind of performance can be expected from
  71	  a particular compression algorithm please refer to the benchmarks
  72	  available at the following LWN page:
  73	  https://lwn.net/Articles/751795/
  74
  75	  If in doubt, select 'LZO'.
  76
  77	  The selection made here can be overridden by using the kernel
  78	  command line 'zswap.compressor=' option.
  79
  80config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
  81	bool "Deflate"
  82	select CRYPTO_DEFLATE
  83	help
  84	  Use the Deflate algorithm as the default compression algorithm.
  85
  86config ZSWAP_COMPRESSOR_DEFAULT_LZO
  87	bool "LZO"
  88	select CRYPTO_LZO
  89	help
  90	  Use the LZO algorithm as the default compression algorithm.
  91
  92config ZSWAP_COMPRESSOR_DEFAULT_842
  93	bool "842"
  94	select CRYPTO_842
  95	help
  96	  Use the 842 algorithm as the default compression algorithm.
  97
  98config ZSWAP_COMPRESSOR_DEFAULT_LZ4
  99	bool "LZ4"
 100	select CRYPTO_LZ4
 101	help
 102	  Use the LZ4 algorithm as the default compression algorithm.
 103
 104config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
 105	bool "LZ4HC"
 106	select CRYPTO_LZ4HC
 107	help
 108	  Use the LZ4HC algorithm as the default compression algorithm.
 109
 110config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
 111	bool "zstd"
 112	select CRYPTO_ZSTD
 113	help
 114	  Use the zstd algorithm as the default compression algorithm.
 115endchoice
 116
 117config ZSWAP_COMPRESSOR_DEFAULT
 118       string
 119       depends on ZSWAP
 120       default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
 121       default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO
 122       default "842" if ZSWAP_COMPRESSOR_DEFAULT_842
 123       default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4
 124       default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
 125       default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
 126       default ""
 127
 128choice
 129	prompt "Default allocator"
 130	depends on ZSWAP
 131	default ZSWAP_ZPOOL_DEFAULT_ZSMALLOC if MMU
 132	default ZSWAP_ZPOOL_DEFAULT_ZBUD
 133	help
 134	  Selects the default allocator for the compressed cache for
 135	  swap pages.
 136	  The default is 'zbud' for compatibility, however please do
 137	  read the description of each of the allocators below before
 138	  making a right choice.
 139
 140	  The selection made here can be overridden by using the kernel
 141	  command line 'zswap.zpool=' option.
 142
 143config ZSWAP_ZPOOL_DEFAULT_ZBUD
 144	bool "zbud"
 145	select ZBUD
 146	help
 147	  Use the zbud allocator as the default allocator.
 148
 149config ZSWAP_ZPOOL_DEFAULT_Z3FOLD_DEPRECATED
 150	bool "z3foldi (DEPRECATED)"
 151	select Z3FOLD_DEPRECATED
 152	help
 153	  Use the z3fold allocator as the default allocator.
 154
 155	  Deprecated and scheduled for removal in a few cycles,
 156	  see CONFIG_Z3FOLD_DEPRECATED.
 157
 158config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
 159	bool "zsmalloc"
 160	select ZSMALLOC
 161	help
 162	  Use the zsmalloc allocator as the default allocator.
 163endchoice
 164
 165config ZSWAP_ZPOOL_DEFAULT
 166       string
 167       depends on ZSWAP
 168       default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
 169       default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD_DEPRECATED
 170       default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
 171       default ""
 172
 173config ZBUD
 174	tristate "2:1 compression allocator (zbud)"
 175	depends on ZSWAP
 176	help
 177	  A special purpose allocator for storing compressed pages.
 178	  It is designed to store up to two compressed pages per physical
 179	  page.  While this design limits storage density, it has simple and
 180	  deterministic reclaim properties that make it preferable to a higher
 181	  density approach when reclaim will be used.
 182
 183config Z3FOLD_DEPRECATED
 184	tristate "3:1 compression allocator (z3fold) (DEPRECATED)"
 185	depends on ZSWAP
 186	help
 187	  Deprecated and scheduled for removal in a few cycles. If you have
 188	  a good reason for using Z3FOLD over ZSMALLOC, please contact
 189	  linux-mm@kvack.org and the zswap maintainers.
 190
 191	  A special purpose allocator for storing compressed pages.
 192	  It is designed to store up to three compressed pages per physical
 193	  page. It is a ZBUD derivative so the simplicity and determinism are
 194	  still there.
 195
 196config Z3FOLD
 197	tristate
 198	default y if Z3FOLD_DEPRECATED=y
 199	default m if Z3FOLD_DEPRECATED=m
 200	depends on Z3FOLD_DEPRECATED
 201
 202config ZSMALLOC
 203	tristate
 204	prompt "N:1 compression allocator (zsmalloc)" if (ZSWAP || ZRAM)
 205	depends on MMU
 206	help
 207	  zsmalloc is a slab-based memory allocator designed to store
 208	  pages of various compression levels efficiently. It achieves
 209	  the highest storage density with the least amount of fragmentation.
 210
 211config ZSMALLOC_STAT
 212	bool "Export zsmalloc statistics"
 213	depends on ZSMALLOC
 214	select DEBUG_FS
 215	help
 216	  This option enables code in the zsmalloc to collect various
 217	  statistics about what's happening in zsmalloc and exports that
 218	  information to userspace via debugfs.
 219	  If unsure, say N.
 220
 221config ZSMALLOC_CHAIN_SIZE
 222	int "Maximum number of physical pages per-zspage"
 223	default 8
 224	range 4 16
 225	depends on ZSMALLOC
 226	help
 227	  This option sets the upper limit on the number of physical pages
 228	  that a zmalloc page (zspage) can consist of. The optimal zspage
 229	  chain size is calculated for each size class during the
 230	  initialization of the pool.
 231
 232	  Changing this option can alter the characteristics of size classes,
 233	  such as the number of pages per zspage and the number of objects
 234	  per zspage. This can also result in different configurations of
 235	  the pool, as zsmalloc merges size classes with similar
 236	  characteristics.
 237
 238	  For more information, see zsmalloc documentation.
 239
 240menu "Slab allocator options"
 241
 242config SLUB
 243	def_bool y
 244
 245config SLUB_TINY
 246	bool "Configure for minimal memory footprint"
 247	depends on EXPERT
 248	select SLAB_MERGE_DEFAULT
 249	help
 250	   Configures the slab allocator in a way to achieve minimal memory
 251	   footprint, sacrificing scalability, debugging and other features.
 252	   This is intended only for the smallest system that had used the
 253	   SLOB allocator and is not recommended for systems with more than
 254	   16MB RAM.
 255
 256	   If unsure, say N.
 257
 258config SLAB_MERGE_DEFAULT
 259	bool "Allow slab caches to be merged"
 260	default y
 261	help
 262	  For reduced kernel memory fragmentation, slab caches can be
 263	  merged when they share the same size and other characteristics.
 264	  This carries a risk of kernel heap overflows being able to
 265	  overwrite objects from merged caches (and more easily control
 266	  cache layout), which makes such heap attacks easier to exploit
 267	  by attackers. By keeping caches unmerged, these kinds of exploits
 268	  can usually only damage objects in the same cache. To disable
 269	  merging at runtime, "slab_nomerge" can be passed on the kernel
 270	  command line.
 271
 272config SLAB_FREELIST_RANDOM
 273	bool "Randomize slab freelist"
 274	depends on !SLUB_TINY
 275	help
 276	  Randomizes the freelist order used on creating new pages. This
 277	  security feature reduces the predictability of the kernel slab
 278	  allocator against heap overflows.
 279
 280config SLAB_FREELIST_HARDENED
 281	bool "Harden slab freelist metadata"
 282	depends on !SLUB_TINY
 283	help
 284	  Many kernel heap attacks try to target slab cache metadata and
 285	  other infrastructure. This options makes minor performance
 286	  sacrifices to harden the kernel slab allocator against common
 287	  freelist exploit methods.
 288
 289config SLAB_BUCKETS
 290	bool "Support allocation from separate kmalloc buckets"
 291	depends on !SLUB_TINY
 292	default SLAB_FREELIST_HARDENED
 293	help
 294	  Kernel heap attacks frequently depend on being able to create
 295	  specifically-sized allocations with user-controlled contents
 296	  that will be allocated into the same kmalloc bucket as a
 297	  target object. To avoid sharing these allocation buckets,
 298	  provide an explicitly separated set of buckets to be used for
 299	  user-controlled allocations. This may very slightly increase
 300	  memory fragmentation, though in practice it's only a handful
 301	  of extra pages since the bulk of user-controlled allocations
 302	  are relatively long-lived.
 303
 304	  If unsure, say Y.
 305
 306config SLUB_STATS
 307	default n
 308	bool "Enable performance statistics"
 309	depends on SYSFS && !SLUB_TINY
 310	help
 311	  The statistics are useful to debug slab allocation behavior in
 312	  order find ways to optimize the allocator. This should never be
 313	  enabled for production use since keeping statistics slows down
 314	  the allocator by a few percentage points. The slabinfo command
 315	  supports the determination of the most active slabs to figure
 316	  out which slabs are relevant to a particular load.
 317	  Try running: slabinfo -DA
 318
 319config SLUB_CPU_PARTIAL
 320	default y
 321	depends on SMP && !SLUB_TINY
 322	bool "Enable per cpu partial caches"
 323	help
 324	  Per cpu partial caches accelerate objects allocation and freeing
 325	  that is local to a processor at the price of more indeterminism
 326	  in the latency of the free. On overflow these caches will be cleared
 327	  which requires the taking of locks that may cause latency spikes.
 328	  Typically one would choose no for a realtime system.
 329
 330config RANDOM_KMALLOC_CACHES
 331	default n
 332	depends on !SLUB_TINY
 333	bool "Randomize slab caches for normal kmalloc"
 334	help
 335	  A hardening feature that creates multiple copies of slab caches for
 336	  normal kmalloc allocation and makes kmalloc randomly pick one based
 337	  on code address, which makes the attackers more difficult to spray
 338	  vulnerable memory objects on the heap for the purpose of exploiting
 339	  memory vulnerabilities.
 340
 341	  Currently the number of copies is set to 16, a reasonably large value
 342	  that effectively diverges the memory objects allocated for different
 343	  subsystems or modules into different caches, at the expense of a
 344	  limited degree of memory and CPU overhead that relates to hardware and
 345	  system workload.
 346
 347endmenu # Slab allocator options
 348
 349config SHUFFLE_PAGE_ALLOCATOR
 350	bool "Page allocator randomization"
 351	default SLAB_FREELIST_RANDOM && ACPI_NUMA
 352	help
 353	  Randomization of the page allocator improves the average
 354	  utilization of a direct-mapped memory-side-cache. See section
 355	  5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
 356	  6.2a specification for an example of how a platform advertises
 357	  the presence of a memory-side-cache. There are also incidental
 358	  security benefits as it reduces the predictability of page
 359	  allocations to compliment SLAB_FREELIST_RANDOM, but the
 360	  default granularity of shuffling on the MAX_PAGE_ORDER i.e, 10th
 361	  order of pages is selected based on cache utilization benefits
 362	  on x86.
 363
 364	  While the randomization improves cache utilization it may
 365	  negatively impact workloads on platforms without a cache. For
 366	  this reason, by default, the randomization is not enabled even
 367	  if SHUFFLE_PAGE_ALLOCATOR=y. The randomization may be force enabled
 368	  with the 'page_alloc.shuffle' kernel command line parameter.
 
 369
 370	  Say Y if unsure.
 371
 372config COMPAT_BRK
 373	bool "Disable heap randomization"
 374	default y
 375	help
 376	  Randomizing heap placement makes heap exploits harder, but it
 377	  also breaks ancient binaries (including anything libc5 based).
 378	  This option changes the bootup default to heap randomization
 379	  disabled, and can be overridden at runtime by setting
 380	  /proc/sys/kernel/randomize_va_space to 2.
 381
 382	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
 383
 384config MMAP_ALLOW_UNINITIALIZED
 385	bool "Allow mmapped anonymous memory to be uninitialized"
 386	depends on EXPERT && !MMU
 387	default n
 388	help
 389	  Normally, and according to the Linux spec, anonymous memory obtained
 390	  from mmap() has its contents cleared before it is passed to
 391	  userspace.  Enabling this config option allows you to request that
 392	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
 393	  providing a huge performance boost.  If this option is not enabled,
 394	  then the flag will be ignored.
 395
 396	  This is taken advantage of by uClibc's malloc(), and also by
 397	  ELF-FDPIC binfmt's brk and stack allocator.
 398
 399	  Because of the obvious security issues, this option should only be
 400	  enabled on embedded devices where you control what is run in
 401	  userspace.  Since that isn't generally a problem on no-MMU systems,
 402	  it is normally safe to say Y here.
 403
 404	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
 405
 406config SELECT_MEMORY_MODEL
 407	def_bool y
 408	depends on ARCH_SELECT_MEMORY_MODEL
 409
 410choice
 411	prompt "Memory model"
 412	depends on SELECT_MEMORY_MODEL
 413	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
 414	default FLATMEM_MANUAL
 415	help
 416	  This option allows you to change some of the ways that
 417	  Linux manages its memory internally. Most users will
 418	  only have one option here selected by the architecture
 419	  configuration. This is normal.
 420
 421config FLATMEM_MANUAL
 422	bool "Flat Memory"
 423	depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
 424	help
 425	  This option is best suited for non-NUMA systems with
 426	  flat address space. The FLATMEM is the most efficient
 427	  system in terms of performance and resource consumption
 428	  and it is the best option for smaller systems.
 429
 430	  For systems that have holes in their physical address
 431	  spaces and for features like NUMA and memory hotplug,
 432	  choose "Sparse Memory".
 433
 434	  If unsure, choose this option (Flat Memory) over any other.
 435
 436config SPARSEMEM_MANUAL
 437	bool "Sparse Memory"
 438	depends on ARCH_SPARSEMEM_ENABLE
 439	help
 440	  This will be the only option for some systems, including
 441	  memory hot-plug systems.  This is normal.
 442
 443	  This option provides efficient support for systems with
 444	  holes is their physical address space and allows memory
 445	  hot-plug and hot-remove.
 446
 447	  If unsure, choose "Flat Memory" over this option.
 448
 449endchoice
 450
 451config SPARSEMEM
 452	def_bool y
 453	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
 454
 455config FLATMEM
 456	def_bool y
 457	depends on !SPARSEMEM || FLATMEM_MANUAL
 458
 459#
 460# SPARSEMEM_EXTREME (which is the default) does some bootmem
 461# allocations when sparse_init() is called.  If this cannot
 462# be done on your architecture, select this option.  However,
 463# statically allocating the mem_section[] array can potentially
 464# consume vast quantities of .bss, so be careful.
 465#
 466# This option will also potentially produce smaller runtime code
 467# with gcc 3.4 and later.
 468#
 469config SPARSEMEM_STATIC
 470	bool
 471
 472#
 473# Architecture platforms which require a two level mem_section in SPARSEMEM
 474# must select this option. This is usually for architecture platforms with
 475# an extremely sparse physical address space.
 476#
 477config SPARSEMEM_EXTREME
 478	def_bool y
 479	depends on SPARSEMEM && !SPARSEMEM_STATIC
 480
 481config SPARSEMEM_VMEMMAP_ENABLE
 482	bool
 483
 484config SPARSEMEM_VMEMMAP
 485	bool "Sparse Memory virtual memmap"
 486	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
 487	default y
 488	help
 489	  SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
 490	  pfn_to_page and page_to_pfn operations.  This is the most
 491	  efficient option when sufficient kernel resources are available.
 492#
 493# Select this config option from the architecture Kconfig, if it is preferred
 494# to enable the feature of HugeTLB/dev_dax vmemmap optimization.
 495#
 496config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
 497	bool
 498
 499config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
 500	bool
 501
 502config HAVE_MEMBLOCK_PHYS_MAP
 503	bool
 504
 505config HAVE_GUP_FAST
 506	depends on MMU
 507	bool
 508
 509# Don't discard allocated memory used to track "memory" and "reserved" memblocks
 510# after early boot, so it can still be used to test for validity of memory.
 511# Also, memblocks are updated with memory hot(un)plug.
 512config ARCH_KEEP_MEMBLOCK
 513	bool
 514
 515# Keep arch NUMA mapping infrastructure post-init.
 516config NUMA_KEEP_MEMINFO
 517	bool
 518
 519config MEMORY_ISOLATION
 520	bool
 521
 522# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
 523# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
 524# /dev/mem.
 525config EXCLUSIVE_SYSTEM_RAM
 526	def_bool y
 527	depends on !DEVMEM || STRICT_DEVMEM
 528
 529#
 530# Only be set on architectures that have completely implemented memory hotplug
 531# feature. If you are not sure, don't touch it.
 532#
 533config HAVE_BOOTMEM_INFO_NODE
 534	def_bool n
 535
 536config ARCH_ENABLE_MEMORY_HOTPLUG
 537	bool
 538
 539config ARCH_ENABLE_MEMORY_HOTREMOVE
 540	bool
 541
 542# eventually, we can have this option just 'select SPARSEMEM'
 543menuconfig MEMORY_HOTPLUG
 544	bool "Memory hotplug"
 545	select MEMORY_ISOLATION
 546	depends on SPARSEMEM
 547	depends on ARCH_ENABLE_MEMORY_HOTPLUG
 548	depends on 64BIT
 549	select NUMA_KEEP_MEMINFO if NUMA
 550
 551if MEMORY_HOTPLUG
 552
 553config MEMORY_HOTPLUG_DEFAULT_ONLINE
 554	bool "Online the newly added memory blocks by default"
 555	depends on MEMORY_HOTPLUG
 556	help
 557	  This option sets the default policy setting for memory hotplug
 558	  onlining policy (/sys/devices/system/memory/auto_online_blocks) which
 559	  determines what happens to newly added memory regions. Policy setting
 560	  can always be changed at runtime.
 561	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
 562
 563	  Say Y here if you want all hot-plugged memory blocks to appear in
 564	  'online' state by default.
 565	  Say N here if you want the default policy to keep all hot-plugged
 566	  memory blocks in 'offline' state.
 567
 568config MEMORY_HOTREMOVE
 569	bool "Allow for memory hot remove"
 570	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
 571	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
 572	depends on MIGRATION
 573
 574config MHP_MEMMAP_ON_MEMORY
 575	def_bool y
 576	depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP
 577	depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
 578
 579endif # MEMORY_HOTPLUG
 580
 581config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
 582       bool
 583
 584# Heavily threaded applications may benefit from splitting the mm-wide
 585# page_table_lock, so that faults on different parts of the user address
 586# space can be handled with less contention: split it at this NR_CPUS.
 587# Default to 4 for wider testing, though 8 might be more appropriate.
 588# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
 589# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
 590# SPARC32 allocates multiple pte tables within a single page, and therefore
 591# a per-page lock leads to problems when multiple tables need to be locked
 592# at the same time (e.g. copy_page_range()).
 593# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
 594#
 595config SPLIT_PTE_PTLOCKS
 596	def_bool y
 597	depends on MMU
 598	depends on SMP
 599	depends on NR_CPUS >= 4
 600	depends on !ARM || CPU_CACHE_VIPT
 601	depends on !PARISC || PA20
 602	depends on !SPARC32
 603
 604config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 605	bool
 606
 607config SPLIT_PMD_PTLOCKS
 608	def_bool y
 609	depends on SPLIT_PTE_PTLOCKS && ARCH_ENABLE_SPLIT_PMD_PTLOCK
 610
 611#
 612# support for memory balloon
 613config MEMORY_BALLOON
 614	bool
 615
 616#
 617# support for memory balloon compaction
 618config BALLOON_COMPACTION
 619	bool "Allow for balloon memory compaction/migration"
 620	default y
 621	depends on COMPACTION && MEMORY_BALLOON
 622	help
 623	  Memory fragmentation introduced by ballooning might reduce
 624	  significantly the number of 2MB contiguous memory blocks that can be
 625	  used within a guest, thus imposing performance penalties associated
 626	  with the reduced number of transparent huge pages that could be used
 627	  by the guest workload. Allowing the compaction & migration for memory
 628	  pages enlisted as being part of memory balloon devices avoids the
 629	  scenario aforementioned and helps improving memory defragmentation.
 630
 631#
 632# support for memory compaction
 633config COMPACTION
 634	bool "Allow for memory compaction"
 635	default y
 636	select MIGRATION
 637	depends on MMU
 638	help
 639	  Compaction is the only memory management component to form
 640	  high order (larger physically contiguous) memory blocks
 641	  reliably. The page allocator relies on compaction heavily and
 642	  the lack of the feature can lead to unexpected OOM killer
 643	  invocations for high order memory requests. You shouldn't
 644	  disable this option unless there really is a strong reason for
 645	  it and then we would be really interested to hear about that at
 646	  linux-mm@kvack.org.
 647
 648config COMPACT_UNEVICTABLE_DEFAULT
 649	int
 650	depends on COMPACTION
 651	default 0 if PREEMPT_RT
 652	default 1
 653
 654#
 655# support for free page reporting
 656config PAGE_REPORTING
 657	bool "Free page reporting"
 
 658	help
 659	  Free page reporting allows for the incremental acquisition of
 660	  free pages from the buddy allocator for the purpose of reporting
 661	  those pages to another entity, such as a hypervisor, so that the
 662	  memory can be freed within the host for other uses.
 663
 664#
 665# support for page migration
 666#
 667config MIGRATION
 668	bool "Page migration"
 669	default y
 670	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
 671	help
 672	  Allows the migration of the physical location of pages of processes
 673	  while the virtual addresses are not changed. This is useful in
 674	  two situations. The first is on NUMA systems to put pages nearer
 675	  to the processors accessing. The second is when allocating huge
 676	  pages as migration can relocate pages to satisfy a huge page
 677	  allocation instead of reclaiming.
 678
 679config DEVICE_MIGRATION
 680	def_bool MIGRATION && ZONE_DEVICE
 681
 682config ARCH_ENABLE_HUGEPAGE_MIGRATION
 683	bool
 684
 685config ARCH_ENABLE_THP_MIGRATION
 686	bool
 687
 688config HUGETLB_PAGE_SIZE_VARIABLE
 689	def_bool n
 690	help
 691	  Allows the pageblock_order value to be dynamic instead of just standard
 692	  HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
 693	  on a platform.
 694
 695	  Note that the pageblock_order cannot exceed MAX_PAGE_ORDER and will be
 696	  clamped down to MAX_PAGE_ORDER.
 697
 698config CONTIG_ALLOC
 699	def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
 700
 701config PCP_BATCH_SCALE_MAX
 702	int "Maximum scale factor of PCP (Per-CPU pageset) batch allocate/free"
 703	default 5
 704	range 0 6
 705	help
 706	  In page allocator, PCP (Per-CPU pageset) is refilled and drained in
 707	  batches.  The batch number is scaled automatically to improve page
 708	  allocation/free throughput.  But too large scale factor may hurt
 709	  latency.  This option sets the upper limit of scale factor to limit
 710	  the maximum latency.
 711
 712config PHYS_ADDR_T_64BIT
 713	def_bool 64BIT
 714
 715config BOUNCE
 716	bool "Enable bounce buffers"
 717	default y
 718	depends on BLOCK && MMU && HIGHMEM
 719	help
 720	  Enable bounce buffers for devices that cannot access the full range of
 721	  memory available to the CPU. Enabled by default when HIGHMEM is
 722	  selected, but you may say n to override this.
 723
 724config MMU_NOTIFIER
 725	bool
 726	select INTERVAL_TREE
 727
 728config KSM
 729	bool "Enable KSM for page merging"
 730	depends on MMU
 731	select XXHASH
 732	help
 733	  Enable Kernel Samepage Merging: KSM periodically scans those areas
 734	  of an application's address space that an app has advised may be
 735	  mergeable.  When it finds pages of identical content, it replaces
 736	  the many instances by a single page with that content, so
 737	  saving memory until one or another app needs to modify the content.
 738	  Recommended for use with KVM, or with other duplicative applications.
 739	  See Documentation/mm/ksm.rst for more information: KSM is inactive
 740	  until a program has madvised that an area is MADV_MERGEABLE, and
 741	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
 742
 743config DEFAULT_MMAP_MIN_ADDR
 744	int "Low address space to protect from user allocation"
 745	depends on MMU
 746	default 4096
 747	help
 748	  This is the portion of low virtual memory which should be protected
 749	  from userspace allocation.  Keeping a user from writing to low pages
 750	  can help reduce the impact of kernel NULL pointer bugs.
 751
 752	  For most arm64, ppc64 and x86 users with lots of address space
 753	  a value of 65536 is reasonable and should cause no problems.
 754	  On arm and other archs it should not be higher than 32768.
 755	  Programs which use vm86 functionality or have some need to map
 756	  this low address space will need CAP_SYS_RAWIO or disable this
 757	  protection by setting the value to 0.
 758
 759	  This value can be changed after boot using the
 760	  /proc/sys/vm/mmap_min_addr tunable.
 761
 762config ARCH_SUPPORTS_MEMORY_FAILURE
 763	bool
 764
 765config MEMORY_FAILURE
 766	depends on MMU
 767	depends on ARCH_SUPPORTS_MEMORY_FAILURE
 768	bool "Enable recovery from hardware memory errors"
 769	select MEMORY_ISOLATION
 770	select RAS
 771	help
 772	  Enables code to recover from some memory failures on systems
 773	  with MCA recovery. This allows a system to continue running
 774	  even when some of its memory has uncorrected errors. This requires
 775	  special hardware support and typically ECC memory.
 776
 777config HWPOISON_INJECT
 778	tristate "HWPoison pages injector"
 779	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
 780	select PROC_PAGE_MONITOR
 781
 782config NOMMU_INITIAL_TRIM_EXCESS
 783	int "Turn on mmap() excess space trimming before booting"
 784	depends on !MMU
 785	default 1
 786	help
 787	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
 788	  of memory on which to store mappings, but it can only ask the system
 789	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
 790	  more than it requires.  To deal with this, mmap() is able to trim off
 791	  the excess and return it to the allocator.
 792
 793	  If trimming is enabled, the excess is trimmed off and returned to the
 794	  system allocator, which can cause extra fragmentation, particularly
 795	  if there are a lot of transient processes.
 796
 797	  If trimming is disabled, the excess is kept, but not used, which for
 798	  long-term mappings means that the space is wasted.
 799
 800	  Trimming can be dynamically controlled through a sysctl option
 801	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
 802	  excess pages there must be before trimming should occur, or zero if
 803	  no trimming is to occur.
 804
 805	  This option specifies the initial value of this option.  The default
 806	  of 1 says that all excess pages should be trimmed.
 807
 808	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
 809
 810config ARCH_WANT_GENERAL_HUGETLB
 811	bool
 812
 813config ARCH_WANTS_THP_SWAP
 814	def_bool n
 815
 816menuconfig TRANSPARENT_HUGEPAGE
 817	bool "Transparent Hugepage Support"
 818	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
 819	select COMPACTION
 820	select XARRAY_MULTI
 821	help
 822	  Transparent Hugepages allows the kernel to use huge pages and
 823	  huge tlb transparently to the applications whenever possible.
 824	  This feature can improve computing performance to certain
 825	  applications by speeding up page faults during memory
 826	  allocation, by reducing the number of tlb misses and by speeding
 827	  up the pagetable walking.
 828
 829	  If memory constrained on embedded, you may want to say N.
 830
 831if TRANSPARENT_HUGEPAGE
 832
 833choice
 834	prompt "Transparent Hugepage Support sysfs defaults"
 835	depends on TRANSPARENT_HUGEPAGE
 836	default TRANSPARENT_HUGEPAGE_ALWAYS
 837	help
 838	  Selects the sysfs defaults for Transparent Hugepage Support.
 839
 840	config TRANSPARENT_HUGEPAGE_ALWAYS
 841		bool "always"
 842	help
 843	  Enabling Transparent Hugepage always, can increase the
 844	  memory footprint of applications without a guaranteed
 845	  benefit but it will work automatically for all applications.
 846
 847	config TRANSPARENT_HUGEPAGE_MADVISE
 848		bool "madvise"
 849	help
 850	  Enabling Transparent Hugepage madvise, will only provide a
 851	  performance improvement benefit to the applications using
 852	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
 853	  memory footprint of applications without a guaranteed
 854	  benefit.
 855
 856	config TRANSPARENT_HUGEPAGE_NEVER
 857		bool "never"
 858	help
 859	  Disable Transparent Hugepage by default. It can still be
 860	  enabled at runtime via sysfs.
 861endchoice
 862
 863config THP_SWAP
 864	def_bool y
 865	depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT
 866	help
 867	  Swap transparent huge pages in one piece, without splitting.
 868	  XXX: For now, swap cluster backing transparent huge page
 869	  will be split after swapout.
 870
 871	  For selection by architectures with reasonable THP sizes.
 872
 873config READ_ONLY_THP_FOR_FS
 874	bool "Read-only THP for filesystems (EXPERIMENTAL)"
 875	depends on TRANSPARENT_HUGEPAGE && SHMEM
 876
 877	help
 878	  Allow khugepaged to put read-only file-backed pages in THP.
 879
 880	  This is marked experimental because it is a new feature. Write
 881	  support of file THPs will be developed in the next few release
 882	  cycles.
 883
 884endif # TRANSPARENT_HUGEPAGE
 885
 886#
 887# The architecture supports pgtable leaves that is larger than PAGE_SIZE
 888#
 889config PGTABLE_HAS_HUGE_LEAVES
 890	def_bool TRANSPARENT_HUGEPAGE || HUGETLB_PAGE
 891
 892# TODO: Allow to be enabled without THP
 893config ARCH_SUPPORTS_HUGE_PFNMAP
 894	def_bool n
 895	depends on TRANSPARENT_HUGEPAGE
 896
 897config ARCH_SUPPORTS_PMD_PFNMAP
 898	def_bool y
 899	depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE
 900
 901config ARCH_SUPPORTS_PUD_PFNMAP
 902	def_bool y
 903	depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 904
 905#
 906# UP and nommu archs use km based percpu allocator
 907#
 908config NEED_PER_CPU_KM
 909	depends on !SMP || !MMU
 910	bool
 911	default y
 912
 913config NEED_PER_CPU_EMBED_FIRST_CHUNK
 914	bool
 915
 916config NEED_PER_CPU_PAGE_FIRST_CHUNK
 917	bool
 918
 919config USE_PERCPU_NUMA_NODE_ID
 920	bool
 921
 922config HAVE_SETUP_PER_CPU_AREA
 923	bool
 924
 925config CMA
 926	bool "Contiguous Memory Allocator"
 927	depends on MMU
 928	select MIGRATION
 929	select MEMORY_ISOLATION
 930	help
 931	  This enables the Contiguous Memory Allocator which allows other
 932	  subsystems to allocate big physically-contiguous blocks of memory.
 933	  CMA reserves a region of memory and allows only movable pages to
 934	  be allocated from it. This way, the kernel can use the memory for
 935	  pagecache and when a subsystem requests for contiguous area, the
 936	  allocated pages are migrated away to serve the contiguous request.
 937
 938	  If unsure, say "n".
 939
 
 
 
 
 
 
 
 
 
 940config CMA_DEBUGFS
 941	bool "CMA debugfs interface"
 942	depends on CMA && DEBUG_FS
 943	help
 944	  Turns on the DebugFS interface for CMA.
 945
 946config CMA_SYSFS
 947	bool "CMA information through sysfs interface"
 948	depends on CMA && SYSFS
 949	help
 950	  This option exposes some sysfs attributes to get information
 951	  from CMA.
 952
 953config CMA_AREAS
 954	int "Maximum count of the CMA areas"
 955	depends on CMA
 956	default 20 if NUMA
 957	default 8
 958	help
 959	  CMA allows to create CMA areas for particular purpose, mainly,
 960	  used as device private area. This parameter sets the maximum
 961	  number of CMA area in the system.
 962
 963	  If unsure, leave the default value "8" in UMA and "20" in NUMA.
 964
 965config MEM_SOFT_DIRTY
 966	bool "Track memory changes"
 967	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
 968	select PROC_PAGE_MONITOR
 969	help
 970	  This option enables memory changes tracking by introducing a
 971	  soft-dirty bit on pte-s. This bit it set when someone writes
 972	  into a page just as regular dirty bit, but unlike the latter
 973	  it can be cleared by hands.
 974
 975	  See Documentation/admin-guide/mm/soft-dirty.rst for more details.
 976
 977config GENERIC_EARLY_IOREMAP
 978	bool
 979
 980config STACK_MAX_DEFAULT_SIZE_MB
 981	int "Default maximum user stack size for 32-bit processes (MB)"
 982	default 100
 983	range 8 2048
 984	depends on STACK_GROWSUP && (!64BIT || COMPAT)
 985	help
 986	  This is the maximum stack size in Megabytes in the VM layout of 32-bit
 987	  user processes when the stack grows upwards (currently only on parisc
 988	  arch) when the RLIMIT_STACK hard limit is unlimited.
 989
 990	  A sane initial value is 100 MB.
 991
 992config DEFERRED_STRUCT_PAGE_INIT
 993	bool "Defer initialisation of struct pages to kthreads"
 994	depends on SPARSEMEM
 995	depends on !NEED_PER_CPU_KM
 996	depends on 64BIT
 997	depends on !KMSAN
 998	select PADATA
 999	help
1000	  Ordinarily all struct pages are initialised during early boot in a
1001	  single thread. On very large machines this can take a considerable
1002	  amount of time. If this option is set, large machines will bring up
1003	  a subset of memmap at boot and then initialise the rest in parallel.
1004	  This has a potential performance impact on tasks running early in the
1005	  lifetime of the system until these kthreads finish the
1006	  initialisation.
1007
1008config PAGE_IDLE_FLAG
1009	bool
1010	select PAGE_EXTENSION if !64BIT
1011	help
1012	  This adds PG_idle and PG_young flags to 'struct page'.  PTE Accessed
1013	  bit writers can set the state of the bit in the flags so that PTE
1014	  Accessed bit readers may avoid disturbance.
1015
1016config IDLE_PAGE_TRACKING
1017	bool "Enable idle page tracking"
1018	depends on SYSFS && MMU
1019	select PAGE_IDLE_FLAG
1020	help
1021	  This feature allows to estimate the amount of user pages that have
1022	  not been touched during a given period of time. This information can
1023	  be useful to tune memory cgroup limits and/or for job placement
1024	  within a compute cluster.
1025
1026	  See Documentation/admin-guide/mm/idle_page_tracking.rst for
1027	  more details.
1028
1029# Architectures which implement cpu_dcache_is_aliasing() to query
1030# whether the data caches are aliased (VIVT or VIPT with dcache
1031# aliasing) need to select this.
1032config ARCH_HAS_CPU_CACHE_ALIASING
1033	bool
1034
1035config ARCH_HAS_CACHE_LINE_SIZE
1036	bool
1037
1038config ARCH_HAS_CURRENT_STACK_POINTER
1039	bool
1040	help
1041	  In support of HARDENED_USERCOPY performing stack variable lifetime
1042	  checking, an architecture-agnostic way to find the stack pointer
1043	  is needed. Once an architecture defines an unsigned long global
1044	  register alias named "current_stack_pointer", this config can be
1045	  selected.
1046
1047config ARCH_HAS_PTE_DEVMAP
1048	bool
1049
1050config ARCH_HAS_ZONE_DMA_SET
1051	bool
1052
1053config ZONE_DMA
1054	bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET
1055	default y if ARM64 || X86
1056
1057config ZONE_DMA32
1058	bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET
1059	depends on !X86_32
1060	default y if ARM64
1061
1062config ZONE_DEVICE
1063	bool "Device memory (pmem, HMM, etc...) hotplug support"
1064	depends on MEMORY_HOTPLUG
1065	depends on MEMORY_HOTREMOVE
1066	depends on SPARSEMEM_VMEMMAP
1067	depends on ARCH_HAS_PTE_DEVMAP
1068	select XARRAY_MULTI
1069
1070	help
1071	  Device memory hotplug support allows for establishing pmem,
1072	  or other device driver discovered memory regions, in the
1073	  memmap. This allows pfn_to_page() lookups of otherwise
1074	  "device-physical" addresses which is needed for using a DAX
1075	  mapping in an O_DIRECT operation, among other things.
1076
1077	  If FS_DAX is enabled, then say Y.
1078
1079#
1080# Helpers to mirror range of the CPU page tables of a process into device page
1081# tables.
1082#
1083config HMM_MIRROR
1084	bool
1085	depends on MMU
1086
1087config GET_FREE_REGION
 
1088	bool
1089
1090config DEVICE_PRIVATE
1091	bool "Unaddressable device memory (GPU memory, ...)"
1092	depends on ZONE_DEVICE
1093	select GET_FREE_REGION
1094
1095	help
1096	  Allows creation of struct pages to represent unaddressable device
1097	  memory; i.e., memory that is only accessible from the device (or
1098	  group of devices). You likely also want to select HMM_MIRROR.
1099
1100config VMAP_PFN
1101	bool
1102
1103config ARCH_USES_HIGH_VMA_FLAGS
1104	bool
1105config ARCH_HAS_PKEYS
1106	bool
1107
1108config ARCH_USES_PG_ARCH_2
1109	bool
1110config ARCH_USES_PG_ARCH_3
1111	bool
 
 
 
 
 
1112
1113config VM_EVENT_COUNTERS
1114	default y
1115	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1116	help
1117	  VM event counters are needed for event counts to be shown.
1118	  This option allows the disabling of the VM event counters
1119	  on EXPERT systems.  /proc/vmstat will only show page counts
1120	  if VM event counters are disabled.
1121
1122config PERCPU_STATS
1123	bool "Collect percpu memory statistics"
1124	help
1125	  This feature collects and exposes statistics via debugfs. The
1126	  information includes global and per chunk statistics, which can
1127	  be used to help understand percpu memory usage.
1128
1129config GUP_TEST
1130	bool "Enable infrastructure for get_user_pages()-related unit tests"
1131	depends on DEBUG_FS
1132	help
1133	  Provides /sys/kernel/debug/gup_test, which in turn provides a way
1134	  to make ioctl calls that can launch kernel-based unit tests for
1135	  the get_user_pages*() and pin_user_pages*() family of API calls.
1136
1137	  These tests include benchmark testing of the _fast variants of
1138	  get_user_pages*() and pin_user_pages*(), as well as smoke tests of
1139	  the non-_fast variants.
1140
1141	  There is also a sub-test that allows running dump_page() on any
1142	  of up to eight pages (selected by command line args) within the
1143	  range of user-space addresses. These pages are either pinned via
1144	  pin_user_pages*(), or pinned via get_user_pages*(), as specified
1145	  by other command line arguments.
1146
1147	  See tools/testing/selftests/mm/gup_test.c
1148
1149comment "GUP_TEST needs to have DEBUG_FS enabled"
1150	depends on !GUP_TEST && !DEBUG_FS
1151
1152config GUP_GET_PXX_LOW_HIGH
1153	bool
1154
1155config DMAPOOL_TEST
1156	tristate "Enable a module to run time tests on dma_pool"
1157	depends on HAS_DMA
1158	help
1159	  Provides a test module that will allocate and free many blocks of
1160	  various sizes and report how long it takes. This is intended to
1161	  provide a consistent way to measure how changes to the
1162	  dma_pool_alloc/free routines affect performance.
1163
1164config ARCH_HAS_PTE_SPECIAL
1165	bool
1166
 
 
 
 
 
 
 
 
 
 
1167config MAPPING_DIRTY_HELPERS
1168        bool
1169
1170config KMAP_LOCAL
1171	bool
1172
1173config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1174	bool
1175
1176# struct io_mapping based helper.  Selected by drivers that need them
1177config IO_MAPPING
1178	bool
1179
1180config MEMFD_CREATE
1181	bool "Enable memfd_create() system call" if EXPERT
1182
1183config SECRETMEM
1184	default y
1185	bool "Enable memfd_secret() system call" if EXPERT
1186	depends on ARCH_HAS_SET_DIRECT_MAP
1187	help
1188	  Enable the memfd_secret() system call with the ability to create
1189	  memory areas visible only in the context of the owning process and
1190	  not mapped to other processes and other kernel page tables.
1191
1192config ANON_VMA_NAME
1193	bool "Anonymous VMA name support"
1194	depends on PROC_FS && ADVISE_SYSCALLS && MMU
1195
1196	help
1197	  Allow naming anonymous virtual memory areas.
1198
1199	  This feature allows assigning names to virtual memory areas. Assigned
1200	  names can be later retrieved from /proc/pid/maps and /proc/pid/smaps
1201	  and help identifying individual anonymous memory areas.
1202	  Assigning a name to anonymous virtual memory area might prevent that
1203	  area from being merged with adjacent virtual memory areas due to the
1204	  difference in their name.
1205
1206config HAVE_ARCH_USERFAULTFD_WP
1207	bool
1208	help
1209	  Arch has userfaultfd write protection support
1210
1211config HAVE_ARCH_USERFAULTFD_MINOR
1212	bool
1213	help
1214	  Arch has userfaultfd minor fault support
1215
1216menuconfig USERFAULTFD
1217	bool "Enable userfaultfd() system call"
1218	depends on MMU
1219	help
1220	  Enable the userfaultfd() system call that allows to intercept and
1221	  handle page faults in userland.
1222
1223if USERFAULTFD
1224config PTE_MARKER_UFFD_WP
1225	bool "Userfaultfd write protection support for shmem/hugetlbfs"
1226	default y
1227	depends on HAVE_ARCH_USERFAULTFD_WP
1228
1229	help
1230	  Allows to create marker PTEs for userfaultfd write protection
1231	  purposes.  It is required to enable userfaultfd write protection on
1232	  file-backed memory types like shmem and hugetlbfs.
1233endif # USERFAULTFD
1234
1235# multi-gen LRU {
1236config LRU_GEN
1237	bool "Multi-Gen LRU"
1238	depends on MMU
1239	# make sure folio->flags has enough spare bits
1240	depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP
1241	help
1242	  A high performance LRU implementation to overcommit memory. See
1243	  Documentation/admin-guide/mm/multigen_lru.rst for details.
1244
1245config LRU_GEN_ENABLED
1246	bool "Enable by default"
1247	depends on LRU_GEN
1248	help
1249	  This option enables the multi-gen LRU by default.
1250
1251config LRU_GEN_STATS
1252	bool "Full stats for debugging"
1253	depends on LRU_GEN
1254	help
1255	  Do not enable this option unless you plan to look at historical stats
1256	  from evicted generations for debugging purpose.
1257
1258	  This option has a per-memcg and per-node memory overhead.
1259
1260config LRU_GEN_WALKS_MMU
1261	def_bool y
1262	depends on LRU_GEN && ARCH_HAS_HW_PTE_YOUNG
1263# }
1264
1265config ARCH_SUPPORTS_PER_VMA_LOCK
1266       def_bool n
1267
1268config PER_VMA_LOCK
1269	def_bool y
1270	depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP
1271	help
1272	  Allow per-vma locking during page fault handling.
1273
1274	  This feature allows locking each virtual memory area separately when
1275	  handling page faults instead of taking mmap_lock.
1276
1277config LOCK_MM_AND_FIND_VMA
1278	bool
1279	depends on !STACK_GROWSUP
1280
1281config IOMMU_MM_DATA
1282	bool
1283
1284config EXECMEM
1285	bool
1286
1287config NUMA_MEMBLKS
1288	bool
1289
1290config NUMA_EMU
1291	bool "NUMA emulation"
1292	depends on NUMA_MEMBLKS
1293	help
1294	  Enable NUMA emulation. A flat machine will be split
1295	  into virtual nodes when booted with "numa=fake=N", where N is the
1296	  number of nodes. This is only useful for debugging.
1297
1298config ARCH_HAS_USER_SHADOW_STACK
1299	bool
1300	help
1301	  The architecture has hardware support for userspace shadow call
1302          stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss).
1303
1304source "mm/damon/Kconfig"
1305
1306endmenu