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 49config ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON 50 bool "Invalidate zswap entries when pages are loaded" 51 depends on ZSWAP 52 help 53 If selected, exclusive loads for zswap will be enabled at boot, 54 otherwise it will be disabled. 55 56 If exclusive loads are enabled, when a page is loaded from zswap, 57 the zswap entry is invalidated at once, as opposed to leaving it 58 in zswap until the swap entry is freed. 59 60 This avoids having two copies of the same page in memory 61 (compressed and uncompressed) after faulting in a page from zswap. 62 The cost is that if the page was never dirtied and needs to be 63 swapped out again, it will be re-compressed. 64 65choice 66 prompt "Default compressor" 67 depends on ZSWAP 68 default ZSWAP_COMPRESSOR_DEFAULT_LZO 69 help 70 Selects the default compression algorithm for the compressed cache 71 for swap pages. 72 73 For an overview what kind of performance can be expected from 74 a particular compression algorithm please refer to the benchmarks 75 available at the following LWN page: 76 https://lwn.net/Articles/751795/ 77 78 If in doubt, select 'LZO'. 79 80 The selection made here can be overridden by using the kernel 81 command line 'zswap.compressor=' option. 82 83config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE 84 bool "Deflate" 85 select CRYPTO_DEFLATE 86 help 87 Use the Deflate algorithm as the default compression algorithm. 88 89config ZSWAP_COMPRESSOR_DEFAULT_LZO 90 bool "LZO" 91 select CRYPTO_LZO 92 help 93 Use the LZO algorithm as the default compression algorithm. 94 95config ZSWAP_COMPRESSOR_DEFAULT_842 96 bool "842" 97 select CRYPTO_842 98 help 99 Use the 842 algorithm as the default compression algorithm. 100 101config ZSWAP_COMPRESSOR_DEFAULT_LZ4 102 bool "LZ4" 103 select CRYPTO_LZ4 104 help 105 Use the LZ4 algorithm as the default compression algorithm. 106 107config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC 108 bool "LZ4HC" 109 select CRYPTO_LZ4HC 110 help 111 Use the LZ4HC algorithm as the default compression algorithm. 112 113config ZSWAP_COMPRESSOR_DEFAULT_ZSTD 114 bool "zstd" 115 select CRYPTO_ZSTD 116 help 117 Use the zstd algorithm as the default compression algorithm. 118endchoice 119 120config ZSWAP_COMPRESSOR_DEFAULT 121 string 122 depends on ZSWAP 123 default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE 124 default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO 125 default "842" if ZSWAP_COMPRESSOR_DEFAULT_842 126 default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4 127 default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC 128 default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD 129 default "" 130 131choice 132 prompt "Default allocator" 133 depends on ZSWAP 134 default ZSWAP_ZPOOL_DEFAULT_ZBUD 135 help 136 Selects the default allocator for the compressed cache for 137 swap pages. 138 The default is 'zbud' for compatibility, however please do 139 read the description of each of the allocators below before 140 making a right choice. 141 142 The selection made here can be overridden by using the kernel 143 command line 'zswap.zpool=' option. 144 145config ZSWAP_ZPOOL_DEFAULT_ZBUD 146 bool "zbud" 147 select ZBUD 148 help 149 Use the zbud allocator as the default allocator. 150 151config ZSWAP_ZPOOL_DEFAULT_Z3FOLD 152 bool "z3fold" 153 select Z3FOLD 154 help 155 Use the z3fold allocator as the default allocator. 156 157config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC 158 bool "zsmalloc" 159 select ZSMALLOC 160 help 161 Use the zsmalloc allocator as the default allocator. 162endchoice 163 164config ZSWAP_ZPOOL_DEFAULT 165 string 166 depends on ZSWAP 167 default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD 168 default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD 169 default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC 170 default "" 171 172config ZBUD 173 tristate "2:1 compression allocator (zbud)" 174 depends on ZSWAP 175 help 176 A special purpose allocator for storing compressed pages. 177 It is designed to store up to two compressed pages per physical 178 page. While this design limits storage density, it has simple and 179 deterministic reclaim properties that make it preferable to a higher 180 density approach when reclaim will be used. 181 182config Z3FOLD 183 tristate "3:1 compression allocator (z3fold)" 184 depends on ZSWAP 185 help 186 A special purpose allocator for storing compressed pages. 187 It is designed to store up to three compressed pages per physical 188 page. It is a ZBUD derivative so the simplicity and determinism are 189 still there. 190 191config ZSMALLOC 192 tristate 193 prompt "N:1 compression allocator (zsmalloc)" if ZSWAP 194 depends on MMU 195 help 196 zsmalloc is a slab-based memory allocator designed to store 197 pages of various compression levels efficiently. It achieves 198 the highest storage density with the least amount of fragmentation. 199 200config ZSMALLOC_STAT 201 bool "Export zsmalloc statistics" 202 depends on ZSMALLOC 203 select DEBUG_FS 204 help 205 This option enables code in the zsmalloc to collect various 206 statistics about what's happening in zsmalloc and exports that 207 information to userspace via debugfs. 208 If unsure, say N. 209 210config ZSMALLOC_CHAIN_SIZE 211 int "Maximum number of physical pages per-zspage" 212 default 8 213 range 4 16 214 depends on ZSMALLOC 215 help 216 This option sets the upper limit on the number of physical pages 217 that a zmalloc page (zspage) can consist of. The optimal zspage 218 chain size is calculated for each size class during the 219 initialization of the pool. 220 221 Changing this option can alter the characteristics of size classes, 222 such as the number of pages per zspage and the number of objects 223 per zspage. This can also result in different configurations of 224 the pool, as zsmalloc merges size classes with similar 225 characteristics. 226 227 For more information, see zsmalloc documentation. 228 229menu "SLAB allocator options" 230 231choice 232 prompt "Choose SLAB allocator" 233 default SLUB 234 help 235 This option allows to select a slab allocator. 236 237config SLAB_DEPRECATED 238 bool "SLAB (DEPRECATED)" 239 depends on !PREEMPT_RT 240 help 241 Deprecated and scheduled for removal in a few cycles. Replaced by 242 SLUB. 243 244 If you cannot migrate to SLUB, please contact linux-mm@kvack.org 245 and the people listed in the SLAB ALLOCATOR section of MAINTAINERS 246 file, explaining why. 247 248 The regular slab allocator that is established and known to work 249 well in all environments. It organizes cache hot objects in 250 per cpu and per node queues. 251 252config SLUB 253 bool "SLUB (Unqueued Allocator)" 254 help 255 SLUB is a slab allocator that minimizes cache line usage 256 instead of managing queues of cached objects (SLAB approach). 257 Per cpu caching is realized using slabs of objects instead 258 of queues of objects. SLUB can use memory efficiently 259 and has enhanced diagnostics. SLUB is the default choice for 260 a slab allocator. 261 262endchoice 263 264config SLAB 265 bool 266 default y 267 depends on SLAB_DEPRECATED 268 269config SLUB_TINY 270 bool "Configure SLUB for minimal memory footprint" 271 depends on SLUB && EXPERT 272 select SLAB_MERGE_DEFAULT 273 help 274 Configures the SLUB allocator in a way to achieve minimal memory 275 footprint, sacrificing scalability, debugging and other features. 276 This is intended only for the smallest system that had used the 277 SLOB allocator and is not recommended for systems with more than 278 16MB RAM. 279 280 If unsure, say N. 281 282config SLAB_MERGE_DEFAULT 283 bool "Allow slab caches to be merged" 284 default y 285 depends on SLAB || SLUB 286 help 287 For reduced kernel memory fragmentation, slab caches can be 288 merged when they share the same size and other characteristics. 289 This carries a risk of kernel heap overflows being able to 290 overwrite objects from merged caches (and more easily control 291 cache layout), which makes such heap attacks easier to exploit 292 by attackers. By keeping caches unmerged, these kinds of exploits 293 can usually only damage objects in the same cache. To disable 294 merging at runtime, "slab_nomerge" can be passed on the kernel 295 command line. 296 297config SLAB_FREELIST_RANDOM 298 bool "Randomize slab freelist" 299 depends on SLAB || (SLUB && !SLUB_TINY) 300 help 301 Randomizes the freelist order used on creating new pages. This 302 security feature reduces the predictability of the kernel slab 303 allocator against heap overflows. 304 305config SLAB_FREELIST_HARDENED 306 bool "Harden slab freelist metadata" 307 depends on SLAB || (SLUB && !SLUB_TINY) 308 help 309 Many kernel heap attacks try to target slab cache metadata and 310 other infrastructure. This options makes minor performance 311 sacrifices to harden the kernel slab allocator against common 312 freelist exploit methods. Some slab implementations have more 313 sanity-checking than others. This option is most effective with 314 CONFIG_SLUB. 315 316config SLUB_STATS 317 default n 318 bool "Enable SLUB performance statistics" 319 depends on SLUB && SYSFS && !SLUB_TINY 320 help 321 SLUB statistics are useful to debug SLUBs allocation behavior in 322 order find ways to optimize the allocator. This should never be 323 enabled for production use since keeping statistics slows down 324 the allocator by a few percentage points. The slabinfo command 325 supports the determination of the most active slabs to figure 326 out which slabs are relevant to a particular load. 327 Try running: slabinfo -DA 328 329config SLUB_CPU_PARTIAL 330 default y 331 depends on SLUB && SMP && !SLUB_TINY 332 bool "SLUB per cpu partial cache" 333 help 334 Per cpu partial caches accelerate objects allocation and freeing 335 that is local to a processor at the price of more indeterminism 336 in the latency of the free. On overflow these caches will be cleared 337 which requires the taking of locks that may cause latency spikes. 338 Typically one would choose no for a realtime system. 339 340endmenu # SLAB allocator options 341 342config SHUFFLE_PAGE_ALLOCATOR 343 bool "Page allocator randomization" 344 default SLAB_FREELIST_RANDOM && ACPI_NUMA 345 help 346 Randomization of the page allocator improves the average 347 utilization of a direct-mapped memory-side-cache. See section 348 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI 349 6.2a specification for an example of how a platform advertises 350 the presence of a memory-side-cache. There are also incidental 351 security benefits as it reduces the predictability of page 352 allocations to compliment SLAB_FREELIST_RANDOM, but the 353 default granularity of shuffling on the MAX_ORDER i.e, 10th 354 order of pages is selected based on cache utilization benefits 355 on x86. 356 357 While the randomization improves cache utilization it may 358 negatively impact workloads on platforms without a cache. For 359 this reason, by default, the randomization is enabled only 360 after runtime detection of a direct-mapped memory-side-cache. 361 Otherwise, the randomization may be force enabled with the 362 'page_alloc.shuffle' kernel command line parameter. 363 364 Say Y if unsure. 365 366config COMPAT_BRK 367 bool "Disable heap randomization" 368 default y 369 help 370 Randomizing heap placement makes heap exploits harder, but it 371 also breaks ancient binaries (including anything libc5 based). 372 This option changes the bootup default to heap randomization 373 disabled, and can be overridden at runtime by setting 374 /proc/sys/kernel/randomize_va_space to 2. 375 376 On non-ancient distros (post-2000 ones) N is usually a safe choice. 377 378config MMAP_ALLOW_UNINITIALIZED 379 bool "Allow mmapped anonymous memory to be uninitialized" 380 depends on EXPERT && !MMU 381 default n 382 help 383 Normally, and according to the Linux spec, anonymous memory obtained 384 from mmap() has its contents cleared before it is passed to 385 userspace. Enabling this config option allows you to request that 386 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 387 providing a huge performance boost. If this option is not enabled, 388 then the flag will be ignored. 389 390 This is taken advantage of by uClibc's malloc(), and also by 391 ELF-FDPIC binfmt's brk and stack allocator. 392 393 Because of the obvious security issues, this option should only be 394 enabled on embedded devices where you control what is run in 395 userspace. Since that isn't generally a problem on no-MMU systems, 396 it is normally safe to say Y here. 397 398 See Documentation/admin-guide/mm/nommu-mmap.rst for more information. 399 400config SELECT_MEMORY_MODEL 401 def_bool y 402 depends on ARCH_SELECT_MEMORY_MODEL 403 404choice 405 prompt "Memory model" 406 depends on SELECT_MEMORY_MODEL 407 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT 408 default FLATMEM_MANUAL 409 help 410 This option allows you to change some of the ways that 411 Linux manages its memory internally. Most users will 412 only have one option here selected by the architecture 413 configuration. This is normal. 414 415config FLATMEM_MANUAL 416 bool "Flat Memory" 417 depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE 418 help 419 This option is best suited for non-NUMA systems with 420 flat address space. The FLATMEM is the most efficient 421 system in terms of performance and resource consumption 422 and it is the best option for smaller systems. 423 424 For systems that have holes in their physical address 425 spaces and for features like NUMA and memory hotplug, 426 choose "Sparse Memory". 427 428 If unsure, choose this option (Flat Memory) over any other. 429 430config SPARSEMEM_MANUAL 431 bool "Sparse Memory" 432 depends on ARCH_SPARSEMEM_ENABLE 433 help 434 This will be the only option for some systems, including 435 memory hot-plug systems. This is normal. 436 437 This option provides efficient support for systems with 438 holes is their physical address space and allows memory 439 hot-plug and hot-remove. 440 441 If unsure, choose "Flat Memory" over this option. 442 443endchoice 444 445config SPARSEMEM 446 def_bool y 447 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL 448 449config FLATMEM 450 def_bool y 451 depends on !SPARSEMEM || FLATMEM_MANUAL 452 453# 454# SPARSEMEM_EXTREME (which is the default) does some bootmem 455# allocations when sparse_init() is called. If this cannot 456# be done on your architecture, select this option. However, 457# statically allocating the mem_section[] array can potentially 458# consume vast quantities of .bss, so be careful. 459# 460# This option will also potentially produce smaller runtime code 461# with gcc 3.4 and later. 462# 463config SPARSEMEM_STATIC 464 bool 465 466# 467# Architecture platforms which require a two level mem_section in SPARSEMEM 468# must select this option. This is usually for architecture platforms with 469# an extremely sparse physical address space. 470# 471config SPARSEMEM_EXTREME 472 def_bool y 473 depends on SPARSEMEM && !SPARSEMEM_STATIC 474 475config SPARSEMEM_VMEMMAP_ENABLE 476 bool 477 478config SPARSEMEM_VMEMMAP 479 bool "Sparse Memory virtual memmap" 480 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE 481 default y 482 help 483 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise 484 pfn_to_page and page_to_pfn operations. This is the most 485 efficient option when sufficient kernel resources are available. 486# 487# Select this config option from the architecture Kconfig, if it is preferred 488# to enable the feature of HugeTLB/dev_dax vmemmap optimization. 489# 490config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP 491 bool 492 493config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP 494 bool 495 496config HAVE_MEMBLOCK_PHYS_MAP 497 bool 498 499config HAVE_FAST_GUP 500 depends on MMU 501 bool 502 503# Don't discard allocated memory used to track "memory" and "reserved" memblocks 504# after early boot, so it can still be used to test for validity of memory. 505# Also, memblocks are updated with memory hot(un)plug. 506config ARCH_KEEP_MEMBLOCK 507 bool 508 509# Keep arch NUMA mapping infrastructure post-init. 510config NUMA_KEEP_MEMINFO 511 bool 512 513config MEMORY_ISOLATION 514 bool 515 516# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked 517# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via 518# /dev/mem. 519config EXCLUSIVE_SYSTEM_RAM 520 def_bool y 521 depends on !DEVMEM || STRICT_DEVMEM 522 523# 524# Only be set on architectures that have completely implemented memory hotplug 525# feature. If you are not sure, don't touch it. 526# 527config HAVE_BOOTMEM_INFO_NODE 528 def_bool n 529 530config ARCH_ENABLE_MEMORY_HOTPLUG 531 bool 532 533config ARCH_ENABLE_MEMORY_HOTREMOVE 534 bool 535 536# eventually, we can have this option just 'select SPARSEMEM' 537menuconfig MEMORY_HOTPLUG 538 bool "Memory hotplug" 539 select MEMORY_ISOLATION 540 depends on SPARSEMEM 541 depends on ARCH_ENABLE_MEMORY_HOTPLUG 542 depends on 64BIT 543 select NUMA_KEEP_MEMINFO if NUMA 544 545if MEMORY_HOTPLUG 546 547config MEMORY_HOTPLUG_DEFAULT_ONLINE 548 bool "Online the newly added memory blocks by default" 549 depends on MEMORY_HOTPLUG 550 help 551 This option sets the default policy setting for memory hotplug 552 onlining policy (/sys/devices/system/memory/auto_online_blocks) which 553 determines what happens to newly added memory regions. Policy setting 554 can always be changed at runtime. 555 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 556 557 Say Y here if you want all hot-plugged memory blocks to appear in 558 'online' state by default. 559 Say N here if you want the default policy to keep all hot-plugged 560 memory blocks in 'offline' state. 561 562config MEMORY_HOTREMOVE 563 bool "Allow for memory hot remove" 564 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) 565 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE 566 depends on MIGRATION 567 568config MHP_MEMMAP_ON_MEMORY 569 def_bool y 570 depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP 571 depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 572 573endif # MEMORY_HOTPLUG 574 575# Heavily threaded applications may benefit from splitting the mm-wide 576# page_table_lock, so that faults on different parts of the user address 577# space can be handled with less contention: split it at this NR_CPUS. 578# Default to 4 for wider testing, though 8 might be more appropriate. 579# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. 580# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. 581# SPARC32 allocates multiple pte tables within a single page, and therefore 582# a per-page lock leads to problems when multiple tables need to be locked 583# at the same time (e.g. copy_page_range()). 584# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. 585# 586config SPLIT_PTLOCK_CPUS 587 int 588 default "999999" if !MMU 589 default "999999" if ARM && !CPU_CACHE_VIPT 590 default "999999" if PARISC && !PA20 591 default "999999" if SPARC32 592 default "4" 593 594config ARCH_ENABLE_SPLIT_PMD_PTLOCK 595 bool 596 597# 598# support for memory balloon 599config MEMORY_BALLOON 600 bool 601 602# 603# support for memory balloon compaction 604config BALLOON_COMPACTION 605 bool "Allow for balloon memory compaction/migration" 606 def_bool y 607 depends on COMPACTION && MEMORY_BALLOON 608 help 609 Memory fragmentation introduced by ballooning might reduce 610 significantly the number of 2MB contiguous memory blocks that can be 611 used within a guest, thus imposing performance penalties associated 612 with the reduced number of transparent huge pages that could be used 613 by the guest workload. Allowing the compaction & migration for memory 614 pages enlisted as being part of memory balloon devices avoids the 615 scenario aforementioned and helps improving memory defragmentation. 616 617# 618# support for memory compaction 619config COMPACTION 620 bool "Allow for memory compaction" 621 def_bool y 622 select MIGRATION 623 depends on MMU 624 help 625 Compaction is the only memory management component to form 626 high order (larger physically contiguous) memory blocks 627 reliably. The page allocator relies on compaction heavily and 628 the lack of the feature can lead to unexpected OOM killer 629 invocations for high order memory requests. You shouldn't 630 disable this option unless there really is a strong reason for 631 it and then we would be really interested to hear about that at 632 linux-mm@kvack.org. 633 634config COMPACT_UNEVICTABLE_DEFAULT 635 int 636 depends on COMPACTION 637 default 0 if PREEMPT_RT 638 default 1 639 640# 641# support for free page reporting 642config PAGE_REPORTING 643 bool "Free page reporting" 644 def_bool n 645 help 646 Free page reporting allows for the incremental acquisition of 647 free pages from the buddy allocator for the purpose of reporting 648 those pages to another entity, such as a hypervisor, so that the 649 memory can be freed within the host for other uses. 650 651# 652# support for page migration 653# 654config MIGRATION 655 bool "Page migration" 656 def_bool y 657 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU 658 help 659 Allows the migration of the physical location of pages of processes 660 while the virtual addresses are not changed. This is useful in 661 two situations. The first is on NUMA systems to put pages nearer 662 to the processors accessing. The second is when allocating huge 663 pages as migration can relocate pages to satisfy a huge page 664 allocation instead of reclaiming. 665 666config DEVICE_MIGRATION 667 def_bool MIGRATION && ZONE_DEVICE 668 669config ARCH_ENABLE_HUGEPAGE_MIGRATION 670 bool 671 672config ARCH_ENABLE_THP_MIGRATION 673 bool 674 675config HUGETLB_PAGE_SIZE_VARIABLE 676 def_bool n 677 help 678 Allows the pageblock_order value to be dynamic instead of just standard 679 HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available 680 on a platform. 681 682 Note that the pageblock_order cannot exceed MAX_ORDER and will be 683 clamped down to MAX_ORDER. 684 685config CONTIG_ALLOC 686 def_bool (MEMORY_ISOLATION && COMPACTION) || CMA 687 688config PHYS_ADDR_T_64BIT 689 def_bool 64BIT 690 691config BOUNCE 692 bool "Enable bounce buffers" 693 default y 694 depends on BLOCK && MMU && HIGHMEM 695 help 696 Enable bounce buffers for devices that cannot access the full range of 697 memory available to the CPU. Enabled by default when HIGHMEM is 698 selected, but you may say n to override this. 699 700config MMU_NOTIFIER 701 bool 702 select INTERVAL_TREE 703 704config KSM 705 bool "Enable KSM for page merging" 706 depends on MMU 707 select XXHASH 708 help 709 Enable Kernel Samepage Merging: KSM periodically scans those areas 710 of an application's address space that an app has advised may be 711 mergeable. When it finds pages of identical content, it replaces 712 the many instances by a single page with that content, so 713 saving memory until one or another app needs to modify the content. 714 Recommended for use with KVM, or with other duplicative applications. 715 See Documentation/mm/ksm.rst for more information: KSM is inactive 716 until a program has madvised that an area is MADV_MERGEABLE, and 717 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). 718 719config DEFAULT_MMAP_MIN_ADDR 720 int "Low address space to protect from user allocation" 721 depends on MMU 722 default 4096 723 help 724 This is the portion of low virtual memory which should be protected 725 from userspace allocation. Keeping a user from writing to low pages 726 can help reduce the impact of kernel NULL pointer bugs. 727 728 For most ia64, ppc64 and x86 users with lots of address space 729 a value of 65536 is reasonable and should cause no problems. 730 On arm and other archs it should not be higher than 32768. 731 Programs which use vm86 functionality or have some need to map 732 this low address space will need CAP_SYS_RAWIO or disable this 733 protection by setting the value to 0. 734 735 This value can be changed after boot using the 736 /proc/sys/vm/mmap_min_addr tunable. 737 738config ARCH_SUPPORTS_MEMORY_FAILURE 739 bool 740 741config MEMORY_FAILURE 742 depends on MMU 743 depends on ARCH_SUPPORTS_MEMORY_FAILURE 744 bool "Enable recovery from hardware memory errors" 745 select MEMORY_ISOLATION 746 select RAS 747 help 748 Enables code to recover from some memory failures on systems 749 with MCA recovery. This allows a system to continue running 750 even when some of its memory has uncorrected errors. This requires 751 special hardware support and typically ECC memory. 752 753config HWPOISON_INJECT 754 tristate "HWPoison pages injector" 755 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS 756 select PROC_PAGE_MONITOR 757 758config NOMMU_INITIAL_TRIM_EXCESS 759 int "Turn on mmap() excess space trimming before booting" 760 depends on !MMU 761 default 1 762 help 763 The NOMMU mmap() frequently needs to allocate large contiguous chunks 764 of memory on which to store mappings, but it can only ask the system 765 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 766 more than it requires. To deal with this, mmap() is able to trim off 767 the excess and return it to the allocator. 768 769 If trimming is enabled, the excess is trimmed off and returned to the 770 system allocator, which can cause extra fragmentation, particularly 771 if there are a lot of transient processes. 772 773 If trimming is disabled, the excess is kept, but not used, which for 774 long-term mappings means that the space is wasted. 775 776 Trimming can be dynamically controlled through a sysctl option 777 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 778 excess pages there must be before trimming should occur, or zero if 779 no trimming is to occur. 780 781 This option specifies the initial value of this option. The default 782 of 1 says that all excess pages should be trimmed. 783 784 See Documentation/admin-guide/mm/nommu-mmap.rst for more information. 785 786config ARCH_WANT_GENERAL_HUGETLB 787 bool 788 789config ARCH_WANTS_THP_SWAP 790 def_bool n 791 792menuconfig TRANSPARENT_HUGEPAGE 793 bool "Transparent Hugepage Support" 794 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT 795 select COMPACTION 796 select XARRAY_MULTI 797 help 798 Transparent Hugepages allows the kernel to use huge pages and 799 huge tlb transparently to the applications whenever possible. 800 This feature can improve computing performance to certain 801 applications by speeding up page faults during memory 802 allocation, by reducing the number of tlb misses and by speeding 803 up the pagetable walking. 804 805 If memory constrained on embedded, you may want to say N. 806 807if TRANSPARENT_HUGEPAGE 808 809choice 810 prompt "Transparent Hugepage Support sysfs defaults" 811 depends on TRANSPARENT_HUGEPAGE 812 default TRANSPARENT_HUGEPAGE_ALWAYS 813 help 814 Selects the sysfs defaults for Transparent Hugepage Support. 815 816 config TRANSPARENT_HUGEPAGE_ALWAYS 817 bool "always" 818 help 819 Enabling Transparent Hugepage always, can increase the 820 memory footprint of applications without a guaranteed 821 benefit but it will work automatically for all applications. 822 823 config TRANSPARENT_HUGEPAGE_MADVISE 824 bool "madvise" 825 help 826 Enabling Transparent Hugepage madvise, will only provide a 827 performance improvement benefit to the applications using 828 madvise(MADV_HUGEPAGE) but it won't risk to increase the 829 memory footprint of applications without a guaranteed 830 benefit. 831endchoice 832 833config THP_SWAP 834 def_bool y 835 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT 836 help 837 Swap transparent huge pages in one piece, without splitting. 838 XXX: For now, swap cluster backing transparent huge page 839 will be split after swapout. 840 841 For selection by architectures with reasonable THP sizes. 842 843config READ_ONLY_THP_FOR_FS 844 bool "Read-only THP for filesystems (EXPERIMENTAL)" 845 depends on TRANSPARENT_HUGEPAGE && SHMEM 846 847 help 848 Allow khugepaged to put read-only file-backed pages in THP. 849 850 This is marked experimental because it is a new feature. Write 851 support of file THPs will be developed in the next few release 852 cycles. 853 854endif # TRANSPARENT_HUGEPAGE 855 856# 857# UP and nommu archs use km based percpu allocator 858# 859config NEED_PER_CPU_KM 860 depends on !SMP || !MMU 861 bool 862 default y 863 864config NEED_PER_CPU_EMBED_FIRST_CHUNK 865 bool 866 867config NEED_PER_CPU_PAGE_FIRST_CHUNK 868 bool 869 870config USE_PERCPU_NUMA_NODE_ID 871 bool 872 873config HAVE_SETUP_PER_CPU_AREA 874 bool 875 876config FRONTSWAP 877 bool 878 879config CMA 880 bool "Contiguous Memory Allocator" 881 depends on MMU 882 select MIGRATION 883 select MEMORY_ISOLATION 884 help 885 This enables the Contiguous Memory Allocator which allows other 886 subsystems to allocate big physically-contiguous blocks of memory. 887 CMA reserves a region of memory and allows only movable pages to 888 be allocated from it. This way, the kernel can use the memory for 889 pagecache and when a subsystem requests for contiguous area, the 890 allocated pages are migrated away to serve the contiguous request. 891 892 If unsure, say "n". 893 894config CMA_DEBUG 895 bool "CMA debug messages (DEVELOPMENT)" 896 depends on DEBUG_KERNEL && CMA 897 help 898 Turns on debug messages in CMA. This produces KERN_DEBUG 899 messages for every CMA call as well as various messages while 900 processing calls such as dma_alloc_from_contiguous(). 901 This option does not affect warning and error messages. 902 903config CMA_DEBUGFS 904 bool "CMA debugfs interface" 905 depends on CMA && DEBUG_FS 906 help 907 Turns on the DebugFS interface for CMA. 908 909config CMA_SYSFS 910 bool "CMA information through sysfs interface" 911 depends on CMA && SYSFS 912 help 913 This option exposes some sysfs attributes to get information 914 from CMA. 915 916config CMA_AREAS 917 int "Maximum count of the CMA areas" 918 depends on CMA 919 default 19 if NUMA 920 default 7 921 help 922 CMA allows to create CMA areas for particular purpose, mainly, 923 used as device private area. This parameter sets the maximum 924 number of CMA area in the system. 925 926 If unsure, leave the default value "7" in UMA and "19" in NUMA. 927 928config MEM_SOFT_DIRTY 929 bool "Track memory changes" 930 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS 931 select PROC_PAGE_MONITOR 932 help 933 This option enables memory changes tracking by introducing a 934 soft-dirty bit on pte-s. This bit it set when someone writes 935 into a page just as regular dirty bit, but unlike the latter 936 it can be cleared by hands. 937 938 See Documentation/admin-guide/mm/soft-dirty.rst for more details. 939 940config GENERIC_EARLY_IOREMAP 941 bool 942 943config STACK_MAX_DEFAULT_SIZE_MB 944 int "Default maximum user stack size for 32-bit processes (MB)" 945 default 100 946 range 8 2048 947 depends on STACK_GROWSUP && (!64BIT || COMPAT) 948 help 949 This is the maximum stack size in Megabytes in the VM layout of 32-bit 950 user processes when the stack grows upwards (currently only on parisc 951 arch) when the RLIMIT_STACK hard limit is unlimited. 952 953 A sane initial value is 100 MB. 954 955config DEFERRED_STRUCT_PAGE_INIT 956 bool "Defer initialisation of struct pages to kthreads" 957 depends on SPARSEMEM 958 depends on !NEED_PER_CPU_KM 959 depends on 64BIT 960 select PADATA 961 help 962 Ordinarily all struct pages are initialised during early boot in a 963 single thread. On very large machines this can take a considerable 964 amount of time. If this option is set, large machines will bring up 965 a subset of memmap at boot and then initialise the rest in parallel. 966 This has a potential performance impact on tasks running early in the 967 lifetime of the system until these kthreads finish the 968 initialisation. 969 970config PAGE_IDLE_FLAG 971 bool 972 select PAGE_EXTENSION if !64BIT 973 help 974 This adds PG_idle and PG_young flags to 'struct page'. PTE Accessed 975 bit writers can set the state of the bit in the flags so that PTE 976 Accessed bit readers may avoid disturbance. 977 978config IDLE_PAGE_TRACKING 979 bool "Enable idle page tracking" 980 depends on SYSFS && MMU 981 select PAGE_IDLE_FLAG 982 help 983 This feature allows to estimate the amount of user pages that have 984 not been touched during a given period of time. This information can 985 be useful to tune memory cgroup limits and/or for job placement 986 within a compute cluster. 987 988 See Documentation/admin-guide/mm/idle_page_tracking.rst for 989 more details. 990 991config ARCH_HAS_CACHE_LINE_SIZE 992 bool 993 994config ARCH_HAS_CURRENT_STACK_POINTER 995 bool 996 help 997 In support of HARDENED_USERCOPY performing stack variable lifetime 998 checking, an architecture-agnostic way to find the stack pointer 999 is needed. Once an architecture defines an unsigned long global 1000 register alias named "current_stack_pointer", this config can be 1001 selected. 1002 1003config ARCH_HAS_PTE_DEVMAP 1004 bool 1005 1006config ARCH_HAS_ZONE_DMA_SET 1007 bool 1008 1009config ZONE_DMA 1010 bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET 1011 default y if ARM64 || X86 1012 1013config ZONE_DMA32 1014 bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET 1015 depends on !X86_32 1016 default y if ARM64 1017 1018config ZONE_DEVICE 1019 bool "Device memory (pmem, HMM, etc...) hotplug support" 1020 depends on MEMORY_HOTPLUG 1021 depends on MEMORY_HOTREMOVE 1022 depends on SPARSEMEM_VMEMMAP 1023 depends on ARCH_HAS_PTE_DEVMAP 1024 select XARRAY_MULTI 1025 1026 help 1027 Device memory hotplug support allows for establishing pmem, 1028 or other device driver discovered memory regions, in the 1029 memmap. This allows pfn_to_page() lookups of otherwise 1030 "device-physical" addresses which is needed for using a DAX 1031 mapping in an O_DIRECT operation, among other things. 1032 1033 If FS_DAX is enabled, then say Y. 1034 1035# 1036# Helpers to mirror range of the CPU page tables of a process into device page 1037# tables. 1038# 1039config HMM_MIRROR 1040 bool 1041 depends on MMU 1042 1043config GET_FREE_REGION 1044 depends on SPARSEMEM 1045 bool 1046 1047config DEVICE_PRIVATE 1048 bool "Unaddressable device memory (GPU memory, ...)" 1049 depends on ZONE_DEVICE 1050 select GET_FREE_REGION 1051 1052 help 1053 Allows creation of struct pages to represent unaddressable device 1054 memory; i.e., memory that is only accessible from the device (or 1055 group of devices). You likely also want to select HMM_MIRROR. 1056 1057config VMAP_PFN 1058 bool 1059 1060config ARCH_USES_HIGH_VMA_FLAGS 1061 bool 1062config ARCH_HAS_PKEYS 1063 bool 1064 1065config ARCH_USES_PG_ARCH_X 1066 bool 1067 help 1068 Enable the definition of PG_arch_x page flags with x > 1. Only 1069 suitable for 64-bit architectures with CONFIG_FLATMEM or 1070 CONFIG_SPARSEMEM_VMEMMAP enabled, otherwise there may not be 1071 enough room for additional bits in page->flags. 1072 1073config VM_EVENT_COUNTERS 1074 default y 1075 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1076 help 1077 VM event counters are needed for event counts to be shown. 1078 This option allows the disabling of the VM event counters 1079 on EXPERT systems. /proc/vmstat will only show page counts 1080 if VM event counters are disabled. 1081 1082config PERCPU_STATS 1083 bool "Collect percpu memory statistics" 1084 help 1085 This feature collects and exposes statistics via debugfs. The 1086 information includes global and per chunk statistics, which can 1087 be used to help understand percpu memory usage. 1088 1089config GUP_TEST 1090 bool "Enable infrastructure for get_user_pages()-related unit tests" 1091 depends on DEBUG_FS 1092 help 1093 Provides /sys/kernel/debug/gup_test, which in turn provides a way 1094 to make ioctl calls that can launch kernel-based unit tests for 1095 the get_user_pages*() and pin_user_pages*() family of API calls. 1096 1097 These tests include benchmark testing of the _fast variants of 1098 get_user_pages*() and pin_user_pages*(), as well as smoke tests of 1099 the non-_fast variants. 1100 1101 There is also a sub-test that allows running dump_page() on any 1102 of up to eight pages (selected by command line args) within the 1103 range of user-space addresses. These pages are either pinned via 1104 pin_user_pages*(), or pinned via get_user_pages*(), as specified 1105 by other command line arguments. 1106 1107 See tools/testing/selftests/mm/gup_test.c 1108 1109comment "GUP_TEST needs to have DEBUG_FS enabled" 1110 depends on !GUP_TEST && !DEBUG_FS 1111 1112config GUP_GET_PXX_LOW_HIGH 1113 bool 1114 1115config DMAPOOL_TEST 1116 tristate "Enable a module to run time tests on dma_pool" 1117 depends on HAS_DMA 1118 help 1119 Provides a test module that will allocate and free many blocks of 1120 various sizes and report how long it takes. This is intended to 1121 provide a consistent way to measure how changes to the 1122 dma_pool_alloc/free routines affect performance. 1123 1124config ARCH_HAS_PTE_SPECIAL 1125 bool 1126 1127# 1128# Some architectures require a special hugepage directory format that is 1129# required to support multiple hugepage sizes. For example a4fe3ce76 1130# "powerpc/mm: Allow more flexible layouts for hugepage pagetables" 1131# introduced it on powerpc. This allows for a more flexible hugepage 1132# pagetable layouts. 1133# 1134config ARCH_HAS_HUGEPD 1135 bool 1136 1137config MAPPING_DIRTY_HELPERS 1138 bool 1139 1140config KMAP_LOCAL 1141 bool 1142 1143config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY 1144 bool 1145 1146# struct io_mapping based helper. Selected by drivers that need them 1147config IO_MAPPING 1148 bool 1149 1150config MEMFD_CREATE 1151 bool "Enable memfd_create() system call" if EXPERT 1152 1153config SECRETMEM 1154 default y 1155 bool "Enable memfd_secret() system call" if EXPERT 1156 depends on ARCH_HAS_SET_DIRECT_MAP 1157 help 1158 Enable the memfd_secret() system call with the ability to create 1159 memory areas visible only in the context of the owning process and 1160 not mapped to other processes and other kernel page tables. 1161 1162config ANON_VMA_NAME 1163 bool "Anonymous VMA name support" 1164 depends on PROC_FS && ADVISE_SYSCALLS && MMU 1165 1166 help 1167 Allow naming anonymous virtual memory areas. 1168 1169 This feature allows assigning names to virtual memory areas. Assigned 1170 names can be later retrieved from /proc/pid/maps and /proc/pid/smaps 1171 and help identifying individual anonymous memory areas. 1172 Assigning a name to anonymous virtual memory area might prevent that 1173 area from being merged with adjacent virtual memory areas due to the 1174 difference in their name. 1175 1176config 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 1183config HAVE_ARCH_USERFAULTFD_WP 1184 bool 1185 help 1186 Arch has userfaultfd write protection support 1187 1188config HAVE_ARCH_USERFAULTFD_MINOR 1189 bool 1190 help 1191 Arch has userfaultfd minor fault support 1192 1193config PTE_MARKER_UFFD_WP 1194 bool "Userfaultfd write protection support for shmem/hugetlbfs" 1195 default y 1196 depends on HAVE_ARCH_USERFAULTFD_WP 1197 1198 help 1199 Allows to create marker PTEs for userfaultfd write protection 1200 purposes. It is required to enable userfaultfd write protection on 1201 file-backed memory types like shmem and hugetlbfs. 1202 1203# multi-gen LRU { 1204config LRU_GEN 1205 bool "Multi-Gen LRU" 1206 depends on MMU 1207 # make sure folio->flags has enough spare bits 1208 depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP 1209 help 1210 A high performance LRU implementation to overcommit memory. See 1211 Documentation/admin-guide/mm/multigen_lru.rst for details. 1212 1213config LRU_GEN_ENABLED 1214 bool "Enable by default" 1215 depends on LRU_GEN 1216 help 1217 This option enables the multi-gen LRU by default. 1218 1219config LRU_GEN_STATS 1220 bool "Full stats for debugging" 1221 depends on LRU_GEN 1222 help 1223 Do not enable this option unless you plan to look at historical stats 1224 from evicted generations for debugging purpose. 1225 1226 This option has a per-memcg and per-node memory overhead. 1227# } 1228 1229config ARCH_SUPPORTS_PER_VMA_LOCK 1230 def_bool n 1231 1232config PER_VMA_LOCK 1233 def_bool y 1234 depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP 1235 help 1236 Allow per-vma locking during page fault handling. 1237 1238 This feature allows locking each virtual memory area separately when 1239 handling page faults instead of taking mmap_lock. 1240 1241config LOCK_MM_AND_FIND_VMA 1242 bool 1243 depends on !STACK_GROWSUP 1244 1245source "mm/damon/Kconfig" 1246 1247endmenu 1248