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 FRONTSWAP
  29	select CRYPTO
  30	select ZPOOL
  31	help
  32	  A lightweight compressed cache for swap pages.  It takes
  33	  pages that are in the process of being swapped out and attempts to
  34	  compress them into a dynamically allocated RAM-based memory pool.
  35	  This can result in a significant I/O reduction on swap device and,
  36	  in the case where decompressing from RAM is faster than swap device
  37	  reads, can also improve workload performance.
  38
  39config ZSWAP_DEFAULT_ON
  40	bool "Enable the compressed cache for swap pages by default"
  41	depends on ZSWAP
  42	help
  43	  If selected, the compressed cache for swap pages will be enabled
  44	  at boot, otherwise it will be disabled.
  45
  46	  The selection made here can be overridden by using the kernel
  47	  command line 'zswap.enabled=' option.
  48
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  49choice
  50	prompt "Default compressor"
  51	depends on ZSWAP
  52	default ZSWAP_COMPRESSOR_DEFAULT_LZO
  53	help
  54	  Selects the default compression algorithm for the compressed cache
  55	  for swap pages.
  56
  57	  For an overview what kind of performance can be expected from
  58	  a particular compression algorithm please refer to the benchmarks
  59	  available at the following LWN page:
  60	  https://lwn.net/Articles/751795/
  61
  62	  If in doubt, select 'LZO'.
  63
  64	  The selection made here can be overridden by using the kernel
  65	  command line 'zswap.compressor=' option.
  66
  67config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
  68	bool "Deflate"
  69	select CRYPTO_DEFLATE
  70	help
  71	  Use the Deflate algorithm as the default compression algorithm.
  72
  73config ZSWAP_COMPRESSOR_DEFAULT_LZO
  74	bool "LZO"
  75	select CRYPTO_LZO
  76	help
  77	  Use the LZO algorithm as the default compression algorithm.
  78
  79config ZSWAP_COMPRESSOR_DEFAULT_842
  80	bool "842"
  81	select CRYPTO_842
  82	help
  83	  Use the 842 algorithm as the default compression algorithm.
  84
  85config ZSWAP_COMPRESSOR_DEFAULT_LZ4
  86	bool "LZ4"
  87	select CRYPTO_LZ4
  88	help
  89	  Use the LZ4 algorithm as the default compression algorithm.
  90
  91config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
  92	bool "LZ4HC"
  93	select CRYPTO_LZ4HC
  94	help
  95	  Use the LZ4HC algorithm as the default compression algorithm.
  96
  97config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
  98	bool "zstd"
  99	select CRYPTO_ZSTD
 100	help
 101	  Use the zstd algorithm as the default compression algorithm.
 102endchoice
 103
 104config ZSWAP_COMPRESSOR_DEFAULT
 105       string
 106       depends on ZSWAP
 107       default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
 108       default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO
 109       default "842" if ZSWAP_COMPRESSOR_DEFAULT_842
 110       default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4
 111       default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
 112       default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
 113       default ""
 114
 115choice
 116	prompt "Default allocator"
 117	depends on ZSWAP
 
 118	default ZSWAP_ZPOOL_DEFAULT_ZBUD
 119	help
 120	  Selects the default allocator for the compressed cache for
 121	  swap pages.
 122	  The default is 'zbud' for compatibility, however please do
 123	  read the description of each of the allocators below before
 124	  making a right choice.
 125
 126	  The selection made here can be overridden by using the kernel
 127	  command line 'zswap.zpool=' option.
 128
 129config ZSWAP_ZPOOL_DEFAULT_ZBUD
 130	bool "zbud"
 131	select ZBUD
 132	help
 133	  Use the zbud allocator as the default allocator.
 134
 135config ZSWAP_ZPOOL_DEFAULT_Z3FOLD
 136	bool "z3fold"
 137	select Z3FOLD
 138	help
 139	  Use the z3fold allocator as the default allocator.
 140
 141config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
 142	bool "zsmalloc"
 143	select ZSMALLOC
 144	help
 145	  Use the zsmalloc allocator as the default allocator.
 146endchoice
 147
 148config ZSWAP_ZPOOL_DEFAULT
 149       string
 150       depends on ZSWAP
 151       default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
 152       default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD
 153       default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
 154       default ""
 155
 156config ZBUD
 157	tristate "2:1 compression allocator (zbud)"
 158	depends on ZSWAP
 159	help
 160	  A special purpose allocator for storing compressed pages.
 161	  It is designed to store up to two compressed pages per physical
 162	  page.  While this design limits storage density, it has simple and
 163	  deterministic reclaim properties that make it preferable to a higher
 164	  density approach when reclaim will be used.
 165
 166config Z3FOLD
 167	tristate "3:1 compression allocator (z3fold)"
 168	depends on ZSWAP
 169	help
 170	  A special purpose allocator for storing compressed pages.
 171	  It is designed to store up to three compressed pages per physical
 172	  page. It is a ZBUD derivative so the simplicity and determinism are
 173	  still there.
 174
 175config ZSMALLOC
 176	tristate
 177	prompt "N:1 compression allocator (zsmalloc)" if ZSWAP
 178	depends on MMU
 179	help
 180	  zsmalloc is a slab-based memory allocator designed to store
 181	  pages of various compression levels efficiently. It achieves
 182	  the highest storage density with the least amount of fragmentation.
 183
 184config ZSMALLOC_STAT
 185	bool "Export zsmalloc statistics"
 186	depends on ZSMALLOC
 187	select DEBUG_FS
 188	help
 189	  This option enables code in the zsmalloc to collect various
 190	  statistics about what's happening in zsmalloc and exports that
 191	  information to userspace via debugfs.
 192	  If unsure, say N.
 193
 194menu "SLAB allocator options"
 195
 196choice
 197	prompt "Choose SLAB allocator"
 198	default SLUB
 199	help
 200	   This option allows to select a slab allocator.
 201
 202config SLAB
 203	bool "SLAB"
 204	depends on !PREEMPT_RT
 205	select HAVE_HARDENED_USERCOPY_ALLOCATOR
 206	help
 207	  The regular slab allocator that is established and known to work
 208	  well in all environments. It organizes cache hot objects in
 209	  per cpu and per node queues.
 210
 211config SLUB
 212	bool "SLUB (Unqueued Allocator)"
 213	select HAVE_HARDENED_USERCOPY_ALLOCATOR
 214	help
 215	   SLUB is a slab allocator that minimizes cache line usage
 216	   instead of managing queues of cached objects (SLAB approach).
 217	   Per cpu caching is realized using slabs of objects instead
 218	   of queues of objects. SLUB can use memory efficiently
 219	   and has enhanced diagnostics. SLUB is the default choice for
 220	   a slab allocator.
 
 
 
 
 221
 222config SLOB_DEPRECATED
 223	depends on EXPERT
 224	bool "SLOB (Simple Allocator - DEPRECATED)"
 225	depends on !PREEMPT_RT
 226	help
 227	   Deprecated and scheduled for removal in a few cycles. SLUB
 228	   recommended as replacement. CONFIG_SLUB_TINY can be considered
 229	   on systems with 16MB or less RAM.
 230
 231	   If you need SLOB to stay, please contact linux-mm@kvack.org and
 232	   people listed in the SLAB ALLOCATOR section of MAINTAINERS file,
 233	   with your use case.
 234
 235	   SLOB replaces the stock allocator with a drastically simpler
 236	   allocator. SLOB is generally more space efficient but
 237	   does not perform as well on large systems.
 238
 239endchoice
 240
 241config SLOB
 242	bool
 243	default y
 244	depends on SLOB_DEPRECATED
 245
 246config SLUB_TINY
 247	bool "Configure SLUB for minimal memory footprint"
 248	depends on SLUB && EXPERT
 249	select SLAB_MERGE_DEFAULT
 250	help
 251	   Configures the SLUB allocator in a way to achieve minimal memory
 252	   footprint, sacrificing scalability, debugging and other features.
 253	   This is intended only for the smallest system that had used the
 254	   SLOB allocator and is not recommended for systems with more than
 255	   16MB RAM.
 256
 257	   If unsure, say N.
 258
 259config SLAB_MERGE_DEFAULT
 260	bool "Allow slab caches to be merged"
 261	default y
 262	depends on SLAB || SLUB
 263	help
 264	  For reduced kernel memory fragmentation, slab caches can be
 265	  merged when they share the same size and other characteristics.
 266	  This carries a risk of kernel heap overflows being able to
 267	  overwrite objects from merged caches (and more easily control
 268	  cache layout), which makes such heap attacks easier to exploit
 269	  by attackers. By keeping caches unmerged, these kinds of exploits
 270	  can usually only damage objects in the same cache. To disable
 271	  merging at runtime, "slab_nomerge" can be passed on the kernel
 272	  command line.
 273
 274config SLAB_FREELIST_RANDOM
 275	bool "Randomize slab freelist"
 276	depends on SLAB || (SLUB && !SLUB_TINY)
 277	help
 278	  Randomizes the freelist order used on creating new pages. This
 279	  security feature reduces the predictability of the kernel slab
 280	  allocator against heap overflows.
 281
 282config SLAB_FREELIST_HARDENED
 283	bool "Harden slab freelist metadata"
 284	depends on SLAB || (SLUB && !SLUB_TINY)
 285	help
 286	  Many kernel heap attacks try to target slab cache metadata and
 287	  other infrastructure. This options makes minor performance
 288	  sacrifices to harden the kernel slab allocator against common
 289	  freelist exploit methods. Some slab implementations have more
 290	  sanity-checking than others. This option is most effective with
 291	  CONFIG_SLUB.
 292
 293config SLUB_STATS
 294	default n
 295	bool "Enable SLUB performance statistics"
 296	depends on SLUB && SYSFS && !SLUB_TINY
 297	help
 298	  SLUB statistics are useful to debug SLUBs allocation behavior in
 299	  order find ways to optimize the allocator. This should never be
 300	  enabled for production use since keeping statistics slows down
 301	  the allocator by a few percentage points. The slabinfo command
 302	  supports the determination of the most active slabs to figure
 303	  out which slabs are relevant to a particular load.
 304	  Try running: slabinfo -DA
 305
 306config SLUB_CPU_PARTIAL
 307	default y
 308	depends on SLUB && SMP && !SLUB_TINY
 309	bool "SLUB per cpu partial cache"
 310	help
 311	  Per cpu partial caches accelerate objects allocation and freeing
 312	  that is local to a processor at the price of more indeterminism
 313	  in the latency of the free. On overflow these caches will be cleared
 314	  which requires the taking of locks that may cause latency spikes.
 315	  Typically one would choose no for a realtime system.
 316
 317endmenu # SLAB allocator options
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 318
 319config SHUFFLE_PAGE_ALLOCATOR
 320	bool "Page allocator randomization"
 321	default SLAB_FREELIST_RANDOM && ACPI_NUMA
 322	help
 323	  Randomization of the page allocator improves the average
 324	  utilization of a direct-mapped memory-side-cache. See section
 325	  5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
 326	  6.2a specification for an example of how a platform advertises
 327	  the presence of a memory-side-cache. There are also incidental
 328	  security benefits as it reduces the predictability of page
 329	  allocations to compliment SLAB_FREELIST_RANDOM, but the
 330	  default granularity of shuffling on the "MAX_ORDER - 1" i.e,
 331	  10th order of pages is selected based on cache utilization
 332	  benefits on x86.
 333
 334	  While the randomization improves cache utilization it may
 335	  negatively impact workloads on platforms without a cache. For
 336	  this reason, by default, the randomization is enabled only
 337	  after runtime detection of a direct-mapped memory-side-cache.
 338	  Otherwise, the randomization may be force enabled with the
 339	  'page_alloc.shuffle' kernel command line parameter.
 340
 341	  Say Y if unsure.
 342
 343config COMPAT_BRK
 344	bool "Disable heap randomization"
 345	default y
 346	help
 347	  Randomizing heap placement makes heap exploits harder, but it
 348	  also breaks ancient binaries (including anything libc5 based).
 349	  This option changes the bootup default to heap randomization
 350	  disabled, and can be overridden at runtime by setting
 351	  /proc/sys/kernel/randomize_va_space to 2.
 352
 353	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
 354
 355config MMAP_ALLOW_UNINITIALIZED
 356	bool "Allow mmapped anonymous memory to be uninitialized"
 357	depends on EXPERT && !MMU
 358	default n
 359	help
 360	  Normally, and according to the Linux spec, anonymous memory obtained
 361	  from mmap() has its contents cleared before it is passed to
 362	  userspace.  Enabling this config option allows you to request that
 363	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
 364	  providing a huge performance boost.  If this option is not enabled,
 365	  then the flag will be ignored.
 366
 367	  This is taken advantage of by uClibc's malloc(), and also by
 368	  ELF-FDPIC binfmt's brk and stack allocator.
 369
 370	  Because of the obvious security issues, this option should only be
 371	  enabled on embedded devices where you control what is run in
 372	  userspace.  Since that isn't generally a problem on no-MMU systems,
 373	  it is normally safe to say Y here.
 374
 375	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
 376
 377config SELECT_MEMORY_MODEL
 378	def_bool y
 379	depends on ARCH_SELECT_MEMORY_MODEL
 380
 381choice
 382	prompt "Memory model"
 383	depends on SELECT_MEMORY_MODEL
 384	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
 385	default FLATMEM_MANUAL
 386	help
 387	  This option allows you to change some of the ways that
 388	  Linux manages its memory internally. Most users will
 389	  only have one option here selected by the architecture
 390	  configuration. This is normal.
 391
 392config FLATMEM_MANUAL
 393	bool "Flat Memory"
 394	depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
 395	help
 396	  This option is best suited for non-NUMA systems with
 397	  flat address space. The FLATMEM is the most efficient
 398	  system in terms of performance and resource consumption
 399	  and it is the best option for smaller systems.
 400
 401	  For systems that have holes in their physical address
 402	  spaces and for features like NUMA and memory hotplug,
 403	  choose "Sparse Memory".
 404
 405	  If unsure, choose this option (Flat Memory) over any other.
 406
 407config SPARSEMEM_MANUAL
 408	bool "Sparse Memory"
 409	depends on ARCH_SPARSEMEM_ENABLE
 410	help
 411	  This will be the only option for some systems, including
 412	  memory hot-plug systems.  This is normal.
 413
 414	  This option provides efficient support for systems with
 415	  holes is their physical address space and allows memory
 416	  hot-plug and hot-remove.
 417
 418	  If unsure, choose "Flat Memory" over this option.
 419
 420endchoice
 421
 422config SPARSEMEM
 423	def_bool y
 424	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
 425
 426config FLATMEM
 427	def_bool y
 428	depends on !SPARSEMEM || FLATMEM_MANUAL
 429
 430#
 431# SPARSEMEM_EXTREME (which is the default) does some bootmem
 432# allocations when sparse_init() is called.  If this cannot
 433# be done on your architecture, select this option.  However,
 434# statically allocating the mem_section[] array can potentially
 435# consume vast quantities of .bss, so be careful.
 436#
 437# This option will also potentially produce smaller runtime code
 438# with gcc 3.4 and later.
 439#
 440config SPARSEMEM_STATIC
 441	bool
 442
 443#
 444# Architecture platforms which require a two level mem_section in SPARSEMEM
 445# must select this option. This is usually for architecture platforms with
 446# an extremely sparse physical address space.
 447#
 448config SPARSEMEM_EXTREME
 449	def_bool y
 450	depends on SPARSEMEM && !SPARSEMEM_STATIC
 451
 452config SPARSEMEM_VMEMMAP_ENABLE
 453	bool
 454
 455config SPARSEMEM_VMEMMAP
 456	bool "Sparse Memory virtual memmap"
 457	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
 458	default y
 459	help
 460	  SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
 461	  pfn_to_page and page_to_pfn operations.  This is the most
 462	  efficient option when sufficient kernel resources are available.
 
 
 
 
 
 
 
 
 
 463
 464config HAVE_MEMBLOCK_PHYS_MAP
 465	bool
 466
 467config HAVE_FAST_GUP
 468	depends on MMU
 469	bool
 470
 471# Don't discard allocated memory used to track "memory" and "reserved" memblocks
 472# after early boot, so it can still be used to test for validity of memory.
 473# Also, memblocks are updated with memory hot(un)plug.
 474config ARCH_KEEP_MEMBLOCK
 475	bool
 476
 477# Keep arch NUMA mapping infrastructure post-init.
 478config NUMA_KEEP_MEMINFO
 479	bool
 480
 481config MEMORY_ISOLATION
 482	bool
 483
 484# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
 485# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
 486# /dev/mem.
 487config EXCLUSIVE_SYSTEM_RAM
 488	def_bool y
 489	depends on !DEVMEM || STRICT_DEVMEM
 490
 491#
 492# Only be set on architectures that have completely implemented memory hotplug
 493# feature. If you are not sure, don't touch it.
 494#
 495config HAVE_BOOTMEM_INFO_NODE
 496	def_bool n
 497
 498config ARCH_ENABLE_MEMORY_HOTPLUG
 499	bool
 500
 501config ARCH_ENABLE_MEMORY_HOTREMOVE
 502	bool
 503
 504# eventually, we can have this option just 'select SPARSEMEM'
 505menuconfig MEMORY_HOTPLUG
 506	bool "Memory hotplug"
 507	select MEMORY_ISOLATION
 508	depends on SPARSEMEM
 509	depends on ARCH_ENABLE_MEMORY_HOTPLUG
 510	depends on 64BIT
 511	select NUMA_KEEP_MEMINFO if NUMA
 512
 513if MEMORY_HOTPLUG
 514
 515config MEMORY_HOTPLUG_DEFAULT_ONLINE
 516	bool "Online the newly added memory blocks by default"
 517	depends on MEMORY_HOTPLUG
 518	help
 519	  This option sets the default policy setting for memory hotplug
 520	  onlining policy (/sys/devices/system/memory/auto_online_blocks) which
 521	  determines what happens to newly added memory regions. Policy setting
 522	  can always be changed at runtime.
 523	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
 524
 525	  Say Y here if you want all hot-plugged memory blocks to appear in
 526	  'online' state by default.
 527	  Say N here if you want the default policy to keep all hot-plugged
 528	  memory blocks in 'offline' state.
 529
 530config MEMORY_HOTREMOVE
 531	bool "Allow for memory hot remove"
 532	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
 533	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
 534	depends on MIGRATION
 535
 536config MHP_MEMMAP_ON_MEMORY
 537	def_bool y
 538	depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP
 539	depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
 540
 541endif # MEMORY_HOTPLUG
 542
 
 
 
 543# Heavily threaded applications may benefit from splitting the mm-wide
 544# page_table_lock, so that faults on different parts of the user address
 545# space can be handled with less contention: split it at this NR_CPUS.
 546# Default to 4 for wider testing, though 8 might be more appropriate.
 547# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
 548# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
 549# SPARC32 allocates multiple pte tables within a single page, and therefore
 550# a per-page lock leads to problems when multiple tables need to be locked
 551# at the same time (e.g. copy_page_range()).
 552# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
 553#
 554config SPLIT_PTLOCK_CPUS
 555	int
 556	default "999999" if !MMU
 557	default "999999" if ARM && !CPU_CACHE_VIPT
 558	default "999999" if PARISC && !PA20
 559	default "999999" if SPARC32
 560	default "4"
 561
 562config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 563	bool
 564
 565#
 566# support for memory balloon
 567config MEMORY_BALLOON
 568	bool
 569
 570#
 571# support for memory balloon compaction
 572config BALLOON_COMPACTION
 573	bool "Allow for balloon memory compaction/migration"
 574	def_bool y
 575	depends on COMPACTION && MEMORY_BALLOON
 576	help
 577	  Memory fragmentation introduced by ballooning might reduce
 578	  significantly the number of 2MB contiguous memory blocks that can be
 579	  used within a guest, thus imposing performance penalties associated
 580	  with the reduced number of transparent huge pages that could be used
 581	  by the guest workload. Allowing the compaction & migration for memory
 582	  pages enlisted as being part of memory balloon devices avoids the
 583	  scenario aforementioned and helps improving memory defragmentation.
 584
 585#
 586# support for memory compaction
 587config COMPACTION
 588	bool "Allow for memory compaction"
 589	def_bool y
 590	select MIGRATION
 591	depends on MMU
 592	help
 593	  Compaction is the only memory management component to form
 594	  high order (larger physically contiguous) memory blocks
 595	  reliably. The page allocator relies on compaction heavily and
 596	  the lack of the feature can lead to unexpected OOM killer
 597	  invocations for high order memory requests. You shouldn't
 598	  disable this option unless there really is a strong reason for
 599	  it and then we would be really interested to hear about that at
 600	  linux-mm@kvack.org.
 601
 602config COMPACT_UNEVICTABLE_DEFAULT
 603	int
 604	depends on COMPACTION
 605	default 0 if PREEMPT_RT
 606	default 1
 607
 608#
 609# support for free page reporting
 610config PAGE_REPORTING
 611	bool "Free page reporting"
 612	def_bool n
 613	help
 614	  Free page reporting allows for the incremental acquisition of
 615	  free pages from the buddy allocator for the purpose of reporting
 616	  those pages to another entity, such as a hypervisor, so that the
 617	  memory can be freed within the host for other uses.
 618
 619#
 620# support for page migration
 621#
 622config MIGRATION
 623	bool "Page migration"
 624	def_bool y
 625	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
 626	help
 627	  Allows the migration of the physical location of pages of processes
 628	  while the virtual addresses are not changed. This is useful in
 629	  two situations. The first is on NUMA systems to put pages nearer
 630	  to the processors accessing. The second is when allocating huge
 631	  pages as migration can relocate pages to satisfy a huge page
 632	  allocation instead of reclaiming.
 633
 634config DEVICE_MIGRATION
 635	def_bool MIGRATION && ZONE_DEVICE
 636
 637config ARCH_ENABLE_HUGEPAGE_MIGRATION
 638	bool
 639
 640config ARCH_ENABLE_THP_MIGRATION
 641	bool
 642
 643config HUGETLB_PAGE_SIZE_VARIABLE
 644	def_bool n
 645	help
 646	  Allows the pageblock_order value to be dynamic instead of just standard
 647	  HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
 648	  on a platform.
 649
 650	  Note that the pageblock_order cannot exceed MAX_ORDER - 1 and will be
 651	  clamped down to MAX_ORDER - 1.
 652
 653config CONTIG_ALLOC
 654	def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
 655
 
 
 
 
 
 
 
 
 
 
 
 656config PHYS_ADDR_T_64BIT
 657	def_bool 64BIT
 658
 659config BOUNCE
 660	bool "Enable bounce buffers"
 661	default y
 662	depends on BLOCK && MMU && HIGHMEM
 663	help
 664	  Enable bounce buffers for devices that cannot access the full range of
 665	  memory available to the CPU. Enabled by default when HIGHMEM is
 666	  selected, but you may say n to override this.
 667
 668config MMU_NOTIFIER
 669	bool
 670	select SRCU
 671	select INTERVAL_TREE
 672
 673config KSM
 674	bool "Enable KSM for page merging"
 675	depends on MMU
 676	select XXHASH
 677	help
 678	  Enable Kernel Samepage Merging: KSM periodically scans those areas
 679	  of an application's address space that an app has advised may be
 680	  mergeable.  When it finds pages of identical content, it replaces
 681	  the many instances by a single page with that content, so
 682	  saving memory until one or another app needs to modify the content.
 683	  Recommended for use with KVM, or with other duplicative applications.
 684	  See Documentation/mm/ksm.rst for more information: KSM is inactive
 685	  until a program has madvised that an area is MADV_MERGEABLE, and
 686	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
 687
 688config DEFAULT_MMAP_MIN_ADDR
 689	int "Low address space to protect from user allocation"
 690	depends on MMU
 691	default 4096
 692	help
 693	  This is the portion of low virtual memory which should be protected
 694	  from userspace allocation.  Keeping a user from writing to low pages
 695	  can help reduce the impact of kernel NULL pointer bugs.
 696
 697	  For most ia64, ppc64 and x86 users with lots of address space
 698	  a value of 65536 is reasonable and should cause no problems.
 699	  On arm and other archs it should not be higher than 32768.
 700	  Programs which use vm86 functionality or have some need to map
 701	  this low address space will need CAP_SYS_RAWIO or disable this
 702	  protection by setting the value to 0.
 703
 704	  This value can be changed after boot using the
 705	  /proc/sys/vm/mmap_min_addr tunable.
 706
 707config ARCH_SUPPORTS_MEMORY_FAILURE
 708	bool
 709
 710config MEMORY_FAILURE
 711	depends on MMU
 712	depends on ARCH_SUPPORTS_MEMORY_FAILURE
 713	bool "Enable recovery from hardware memory errors"
 714	select MEMORY_ISOLATION
 715	select RAS
 716	help
 717	  Enables code to recover from some memory failures on systems
 718	  with MCA recovery. This allows a system to continue running
 719	  even when some of its memory has uncorrected errors. This requires
 720	  special hardware support and typically ECC memory.
 721
 722config HWPOISON_INJECT
 723	tristate "HWPoison pages injector"
 724	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
 725	select PROC_PAGE_MONITOR
 726
 727config NOMMU_INITIAL_TRIM_EXCESS
 728	int "Turn on mmap() excess space trimming before booting"
 729	depends on !MMU
 730	default 1
 731	help
 732	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
 733	  of memory on which to store mappings, but it can only ask the system
 734	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
 735	  more than it requires.  To deal with this, mmap() is able to trim off
 736	  the excess and return it to the allocator.
 737
 738	  If trimming is enabled, the excess is trimmed off and returned to the
 739	  system allocator, which can cause extra fragmentation, particularly
 740	  if there are a lot of transient processes.
 741
 742	  If trimming is disabled, the excess is kept, but not used, which for
 743	  long-term mappings means that the space is wasted.
 744
 745	  Trimming can be dynamically controlled through a sysctl option
 746	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
 747	  excess pages there must be before trimming should occur, or zero if
 748	  no trimming is to occur.
 749
 750	  This option specifies the initial value of this option.  The default
 751	  of 1 says that all excess pages should be trimmed.
 752
 753	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
 754
 755config ARCH_WANT_GENERAL_HUGETLB
 756	bool
 757
 758config ARCH_WANTS_THP_SWAP
 759	def_bool n
 760
 761menuconfig TRANSPARENT_HUGEPAGE
 762	bool "Transparent Hugepage Support"
 763	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
 764	select COMPACTION
 765	select XARRAY_MULTI
 766	help
 767	  Transparent Hugepages allows the kernel to use huge pages and
 768	  huge tlb transparently to the applications whenever possible.
 769	  This feature can improve computing performance to certain
 770	  applications by speeding up page faults during memory
 771	  allocation, by reducing the number of tlb misses and by speeding
 772	  up the pagetable walking.
 773
 774	  If memory constrained on embedded, you may want to say N.
 775
 776if TRANSPARENT_HUGEPAGE
 777
 778choice
 779	prompt "Transparent Hugepage Support sysfs defaults"
 780	depends on TRANSPARENT_HUGEPAGE
 781	default TRANSPARENT_HUGEPAGE_ALWAYS
 782	help
 783	  Selects the sysfs defaults for Transparent Hugepage Support.
 784
 785	config TRANSPARENT_HUGEPAGE_ALWAYS
 786		bool "always"
 787	help
 788	  Enabling Transparent Hugepage always, can increase the
 789	  memory footprint of applications without a guaranteed
 790	  benefit but it will work automatically for all applications.
 791
 792	config TRANSPARENT_HUGEPAGE_MADVISE
 793		bool "madvise"
 794	help
 795	  Enabling Transparent Hugepage madvise, will only provide a
 796	  performance improvement benefit to the applications using
 797	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
 798	  memory footprint of applications without a guaranteed
 799	  benefit.
 
 
 
 
 
 
 800endchoice
 801
 802config THP_SWAP
 803	def_bool y
 804	depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT
 805	help
 806	  Swap transparent huge pages in one piece, without splitting.
 807	  XXX: For now, swap cluster backing transparent huge page
 808	  will be split after swapout.
 809
 810	  For selection by architectures with reasonable THP sizes.
 811
 812config READ_ONLY_THP_FOR_FS
 813	bool "Read-only THP for filesystems (EXPERIMENTAL)"
 814	depends on TRANSPARENT_HUGEPAGE && SHMEM
 815
 816	help
 817	  Allow khugepaged to put read-only file-backed pages in THP.
 818
 819	  This is marked experimental because it is a new feature. Write
 820	  support of file THPs will be developed in the next few release
 821	  cycles.
 822
 823endif # TRANSPARENT_HUGEPAGE
 824
 825#
 826# UP and nommu archs use km based percpu allocator
 827#
 828config NEED_PER_CPU_KM
 829	depends on !SMP || !MMU
 830	bool
 831	default y
 832
 833config NEED_PER_CPU_EMBED_FIRST_CHUNK
 834	bool
 835
 836config NEED_PER_CPU_PAGE_FIRST_CHUNK
 837	bool
 838
 839config USE_PERCPU_NUMA_NODE_ID
 840	bool
 841
 842config HAVE_SETUP_PER_CPU_AREA
 843	bool
 844
 845config FRONTSWAP
 846	bool
 847
 848config CMA
 849	bool "Contiguous Memory Allocator"
 850	depends on MMU
 851	select MIGRATION
 852	select MEMORY_ISOLATION
 853	help
 854	  This enables the Contiguous Memory Allocator which allows other
 855	  subsystems to allocate big physically-contiguous blocks of memory.
 856	  CMA reserves a region of memory and allows only movable pages to
 857	  be allocated from it. This way, the kernel can use the memory for
 858	  pagecache and when a subsystem requests for contiguous area, the
 859	  allocated pages are migrated away to serve the contiguous request.
 860
 861	  If unsure, say "n".
 862
 863config CMA_DEBUG
 864	bool "CMA debug messages (DEVELOPMENT)"
 865	depends on DEBUG_KERNEL && CMA
 866	help
 867	  Turns on debug messages in CMA.  This produces KERN_DEBUG
 868	  messages for every CMA call as well as various messages while
 869	  processing calls such as dma_alloc_from_contiguous().
 870	  This option does not affect warning and error messages.
 871
 872config CMA_DEBUGFS
 873	bool "CMA debugfs interface"
 874	depends on CMA && DEBUG_FS
 875	help
 876	  Turns on the DebugFS interface for CMA.
 877
 878config CMA_SYSFS
 879	bool "CMA information through sysfs interface"
 880	depends on CMA && SYSFS
 881	help
 882	  This option exposes some sysfs attributes to get information
 883	  from CMA.
 884
 885config CMA_AREAS
 886	int "Maximum count of the CMA areas"
 887	depends on CMA
 888	default 19 if NUMA
 889	default 7
 890	help
 891	  CMA allows to create CMA areas for particular purpose, mainly,
 892	  used as device private area. This parameter sets the maximum
 893	  number of CMA area in the system.
 894
 895	  If unsure, leave the default value "7" in UMA and "19" in NUMA.
 896
 897config MEM_SOFT_DIRTY
 898	bool "Track memory changes"
 899	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
 900	select PROC_PAGE_MONITOR
 901	help
 902	  This option enables memory changes tracking by introducing a
 903	  soft-dirty bit on pte-s. This bit it set when someone writes
 904	  into a page just as regular dirty bit, but unlike the latter
 905	  it can be cleared by hands.
 906
 907	  See Documentation/admin-guide/mm/soft-dirty.rst for more details.
 908
 909config GENERIC_EARLY_IOREMAP
 910	bool
 911
 912config STACK_MAX_DEFAULT_SIZE_MB
 913	int "Default maximum user stack size for 32-bit processes (MB)"
 914	default 100
 915	range 8 2048
 916	depends on STACK_GROWSUP && (!64BIT || COMPAT)
 917	help
 918	  This is the maximum stack size in Megabytes in the VM layout of 32-bit
 919	  user processes when the stack grows upwards (currently only on parisc
 920	  arch) when the RLIMIT_STACK hard limit is unlimited.
 921
 922	  A sane initial value is 100 MB.
 923
 924config DEFERRED_STRUCT_PAGE_INIT
 925	bool "Defer initialisation of struct pages to kthreads"
 926	depends on SPARSEMEM
 927	depends on !NEED_PER_CPU_KM
 928	depends on 64BIT
 929	select PADATA
 930	help
 931	  Ordinarily all struct pages are initialised during early boot in a
 932	  single thread. On very large machines this can take a considerable
 933	  amount of time. If this option is set, large machines will bring up
 934	  a subset of memmap at boot and then initialise the rest in parallel.
 935	  This has a potential performance impact on tasks running early in the
 936	  lifetime of the system until these kthreads finish the
 937	  initialisation.
 938
 939config PAGE_IDLE_FLAG
 940	bool
 941	select PAGE_EXTENSION if !64BIT
 942	help
 943	  This adds PG_idle and PG_young flags to 'struct page'.  PTE Accessed
 944	  bit writers can set the state of the bit in the flags so that PTE
 945	  Accessed bit readers may avoid disturbance.
 946
 947config IDLE_PAGE_TRACKING
 948	bool "Enable idle page tracking"
 949	depends on SYSFS && MMU
 950	select PAGE_IDLE_FLAG
 951	help
 952	  This feature allows to estimate the amount of user pages that have
 953	  not been touched during a given period of time. This information can
 954	  be useful to tune memory cgroup limits and/or for job placement
 955	  within a compute cluster.
 956
 957	  See Documentation/admin-guide/mm/idle_page_tracking.rst for
 958	  more details.
 959
 
 
 
 
 
 
 960config ARCH_HAS_CACHE_LINE_SIZE
 961	bool
 962
 963config ARCH_HAS_CURRENT_STACK_POINTER
 964	bool
 965	help
 966	  In support of HARDENED_USERCOPY performing stack variable lifetime
 967	  checking, an architecture-agnostic way to find the stack pointer
 968	  is needed. Once an architecture defines an unsigned long global
 969	  register alias named "current_stack_pointer", this config can be
 970	  selected.
 971
 972config ARCH_HAS_PTE_DEVMAP
 973	bool
 974
 975config ARCH_HAS_ZONE_DMA_SET
 976	bool
 977
 978config ZONE_DMA
 979	bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET
 980	default y if ARM64 || X86
 981
 982config ZONE_DMA32
 983	bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET
 984	depends on !X86_32
 985	default y if ARM64
 986
 987config ZONE_DEVICE
 988	bool "Device memory (pmem, HMM, etc...) hotplug support"
 989	depends on MEMORY_HOTPLUG
 990	depends on MEMORY_HOTREMOVE
 991	depends on SPARSEMEM_VMEMMAP
 992	depends on ARCH_HAS_PTE_DEVMAP
 993	select XARRAY_MULTI
 994
 995	help
 996	  Device memory hotplug support allows for establishing pmem,
 997	  or other device driver discovered memory regions, in the
 998	  memmap. This allows pfn_to_page() lookups of otherwise
 999	  "device-physical" addresses which is needed for using a DAX
1000	  mapping in an O_DIRECT operation, among other things.
1001
1002	  If FS_DAX is enabled, then say Y.
1003
1004#
1005# Helpers to mirror range of the CPU page tables of a process into device page
1006# tables.
1007#
1008config HMM_MIRROR
1009	bool
1010	depends on MMU
1011
1012config GET_FREE_REGION
1013	depends on SPARSEMEM
1014	bool
1015
1016config DEVICE_PRIVATE
1017	bool "Unaddressable device memory (GPU memory, ...)"
1018	depends on ZONE_DEVICE
1019	select GET_FREE_REGION
1020
1021	help
1022	  Allows creation of struct pages to represent unaddressable device
1023	  memory; i.e., memory that is only accessible from the device (or
1024	  group of devices). You likely also want to select HMM_MIRROR.
1025
1026config VMAP_PFN
1027	bool
1028
1029config ARCH_USES_HIGH_VMA_FLAGS
1030	bool
1031config ARCH_HAS_PKEYS
1032	bool
1033
1034config ARCH_USES_PG_ARCH_X
1035	bool
1036	help
1037	  Enable the definition of PG_arch_x page flags with x > 1. Only
1038	  suitable for 64-bit architectures with CONFIG_FLATMEM or
1039	  CONFIG_SPARSEMEM_VMEMMAP enabled, otherwise there may not be
1040	  enough room for additional bits in page->flags.
1041
1042config VM_EVENT_COUNTERS
1043	default y
1044	bool "Enable VM event counters for /proc/vmstat" if EXPERT
1045	help
1046	  VM event counters are needed for event counts to be shown.
1047	  This option allows the disabling of the VM event counters
1048	  on EXPERT systems.  /proc/vmstat will only show page counts
1049	  if VM event counters are disabled.
1050
1051config PERCPU_STATS
1052	bool "Collect percpu memory statistics"
1053	help
1054	  This feature collects and exposes statistics via debugfs. The
1055	  information includes global and per chunk statistics, which can
1056	  be used to help understand percpu memory usage.
1057
1058config GUP_TEST
1059	bool "Enable infrastructure for get_user_pages()-related unit tests"
1060	depends on DEBUG_FS
1061	help
1062	  Provides /sys/kernel/debug/gup_test, which in turn provides a way
1063	  to make ioctl calls that can launch kernel-based unit tests for
1064	  the get_user_pages*() and pin_user_pages*() family of API calls.
1065
1066	  These tests include benchmark testing of the _fast variants of
1067	  get_user_pages*() and pin_user_pages*(), as well as smoke tests of
1068	  the non-_fast variants.
1069
1070	  There is also a sub-test that allows running dump_page() on any
1071	  of up to eight pages (selected by command line args) within the
1072	  range of user-space addresses. These pages are either pinned via
1073	  pin_user_pages*(), or pinned via get_user_pages*(), as specified
1074	  by other command line arguments.
1075
1076	  See tools/testing/selftests/vm/gup_test.c
1077
1078comment "GUP_TEST needs to have DEBUG_FS enabled"
1079	depends on !GUP_TEST && !DEBUG_FS
1080
1081config GUP_GET_PXX_LOW_HIGH
1082	bool
1083
 
 
 
 
 
 
 
 
 
1084config ARCH_HAS_PTE_SPECIAL
1085	bool
1086
1087#
1088# Some architectures require a special hugepage directory format that is
1089# required to support multiple hugepage sizes. For example a4fe3ce76
1090# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
1091# introduced it on powerpc.  This allows for a more flexible hugepage
1092# pagetable layouts.
1093#
1094config ARCH_HAS_HUGEPD
1095	bool
1096
1097config MAPPING_DIRTY_HELPERS
1098        bool
1099
1100config KMAP_LOCAL
1101	bool
1102
1103config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1104	bool
1105
1106# struct io_mapping based helper.  Selected by drivers that need them
1107config IO_MAPPING
1108	bool
1109
 
 
 
1110config SECRETMEM
1111	default y
1112	bool "Enable memfd_secret() system call" if EXPERT
1113	depends on ARCH_HAS_SET_DIRECT_MAP
1114	help
1115	  Enable the memfd_secret() system call with the ability to create
1116	  memory areas visible only in the context of the owning process and
1117	  not mapped to other processes and other kernel page tables.
1118
1119config ANON_VMA_NAME
1120	bool "Anonymous VMA name support"
1121	depends on PROC_FS && ADVISE_SYSCALLS && MMU
1122
1123	help
1124	  Allow naming anonymous virtual memory areas.
1125
1126	  This feature allows assigning names to virtual memory areas. Assigned
1127	  names can be later retrieved from /proc/pid/maps and /proc/pid/smaps
1128	  and help identifying individual anonymous memory areas.
1129	  Assigning a name to anonymous virtual memory area might prevent that
1130	  area from being merged with adjacent virtual memory areas due to the
1131	  difference in their name.
1132
1133config USERFAULTFD
1134	bool "Enable userfaultfd() system call"
1135	depends on MMU
1136	help
1137	  Enable the userfaultfd() system call that allows to intercept and
1138	  handle page faults in userland.
1139
1140config HAVE_ARCH_USERFAULTFD_WP
1141	bool
1142	help
1143	  Arch has userfaultfd write protection support
1144
1145config HAVE_ARCH_USERFAULTFD_MINOR
1146	bool
1147	help
1148	  Arch has userfaultfd minor fault support
1149
 
 
 
 
 
 
 
 
1150config PTE_MARKER_UFFD_WP
1151	bool "Userfaultfd write protection support for shmem/hugetlbfs"
1152	default y
1153	depends on HAVE_ARCH_USERFAULTFD_WP
1154
1155	help
1156	  Allows to create marker PTEs for userfaultfd write protection
1157	  purposes.  It is required to enable userfaultfd write protection on
1158	  file-backed memory types like shmem and hugetlbfs.
 
1159
1160# multi-gen LRU {
1161config LRU_GEN
1162	bool "Multi-Gen LRU"
1163	depends on MMU
1164	# make sure folio->flags has enough spare bits
1165	depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP
1166	help
1167	  A high performance LRU implementation to overcommit memory. See
1168	  Documentation/admin-guide/mm/multigen_lru.rst for details.
1169
1170config LRU_GEN_ENABLED
1171	bool "Enable by default"
1172	depends on LRU_GEN
1173	help
1174	  This option enables the multi-gen LRU by default.
1175
1176config LRU_GEN_STATS
1177	bool "Full stats for debugging"
1178	depends on LRU_GEN
1179	help
1180	  Do not enable this option unless you plan to look at historical stats
1181	  from evicted generations for debugging purpose.
1182
1183	  This option has a per-memcg and per-node memory overhead.
 
 
 
 
1184# }
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1185
1186source "mm/damon/Kconfig"
1187
1188endmenu

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