1# SPDX-License-Identifier: GPL-2.0-only 2 3menu "Memory Management options" 4 5# 6# For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can 7# add proper SWAP support to them, in which case this can be remove. 8# 9config ARCH_NO_SWAP 10 bool 11 12config ZPOOL 13 bool 14 15menuconfig SWAP 16 bool "Support for paging of anonymous memory (swap)" 17 depends on MMU && BLOCK && !ARCH_NO_SWAP 18 default y 19 help 20 This option allows you to choose whether you want to have support 21 for so called swap devices or swap files in your kernel that are 22 used to provide more virtual memory than the actual RAM present 23 in your computer. If unsure say Y. 24 25config ZSWAP 26 bool "Compressed cache for swap pages" 27 depends on SWAP 28 select CRYPTO 29 select ZPOOL 30 help 31 A lightweight compressed cache for swap pages. It takes 32 pages that are in the process of being swapped out and attempts to 33 compress them into a dynamically allocated RAM-based memory pool. 34 This can result in a significant I/O reduction on swap device and, 35 in the case where decompressing from RAM is faster than swap device 36 reads, can also improve workload performance. 37 38config ZSWAP_DEFAULT_ON 39 bool "Enable the compressed cache for swap pages by default" 40 depends on ZSWAP 41 help 42 If selected, the compressed cache for swap pages will be enabled 43 at boot, otherwise it will be disabled. 44 45 The selection made here can be overridden by using the kernel 46 command line 'zswap.enabled=' option. 47 48config ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON 49 bool "Invalidate zswap entries when pages are loaded" 50 depends on ZSWAP 51 help 52 If selected, exclusive loads for zswap will be enabled at boot, 53 otherwise it will be disabled. 54 55 If exclusive loads are enabled, when a page is loaded from zswap, 56 the zswap entry is invalidated at once, as opposed to leaving it 57 in zswap until the swap entry is freed. 58 59 This avoids having two copies of the same page in memory 60 (compressed and uncompressed) after faulting in a page from zswap. 61 The cost is that if the page was never dirtied and needs to be 62 swapped out again, it will be re-compressed. 63 64config ZSWAP_SHRINKER_DEFAULT_ON 65 bool "Shrink the zswap pool on memory pressure" 66 depends on ZSWAP 67 default n 68 help 69 If selected, the zswap shrinker will be enabled, and the pages 70 stored in the zswap pool will become available for reclaim (i.e 71 written back to the backing swap device) on memory pressure. 72 73 This means that zswap writeback could happen even if the pool is 74 not yet full, or the cgroup zswap limit has not been reached, 75 reducing the chance that cold pages will reside in the zswap pool 76 and consume memory indefinitely. 77 78choice 79 prompt "Default compressor" 80 depends on ZSWAP 81 default ZSWAP_COMPRESSOR_DEFAULT_LZO 82 help 83 Selects the default compression algorithm for the compressed cache 84 for swap pages. 85 86 For an overview what kind of performance can be expected from 87 a particular compression algorithm please refer to the benchmarks 88 available at the following LWN page: 89 https://lwn.net/Articles/751795/ 90 91 If in doubt, select 'LZO'. 92 93 The selection made here can be overridden by using the kernel 94 command line 'zswap.compressor=' option. 95 96config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE 97 bool "Deflate" 98 select CRYPTO_DEFLATE 99 help 100 Use the Deflate algorithm as the default compression algorithm. 101 102config ZSWAP_COMPRESSOR_DEFAULT_LZO 103 bool "LZO" 104 select CRYPTO_LZO 105 help 106 Use the LZO algorithm as the default compression algorithm. 107 108config ZSWAP_COMPRESSOR_DEFAULT_842 109 bool "842" 110 select CRYPTO_842 111 help 112 Use the 842 algorithm as the default compression algorithm. 113 114config ZSWAP_COMPRESSOR_DEFAULT_LZ4 115 bool "LZ4" 116 select CRYPTO_LZ4 117 help 118 Use the LZ4 algorithm as the default compression algorithm. 119 120config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC 121 bool "LZ4HC" 122 select CRYPTO_LZ4HC 123 help 124 Use the LZ4HC algorithm as the default compression algorithm. 125 126config ZSWAP_COMPRESSOR_DEFAULT_ZSTD 127 bool "zstd" 128 select CRYPTO_ZSTD 129 help 130 Use the zstd algorithm as the default compression algorithm. 131endchoice 132 133config ZSWAP_COMPRESSOR_DEFAULT 134 string 135 depends on ZSWAP 136 default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE 137 default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO 138 default "842" if ZSWAP_COMPRESSOR_DEFAULT_842 139 default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4 140 default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC 141 default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD 142 default "" 143 144choice 145 prompt "Default allocator" 146 depends on ZSWAP 147 default ZSWAP_ZPOOL_DEFAULT_ZSMALLOC if MMU 148 default ZSWAP_ZPOOL_DEFAULT_ZBUD 149 help 150 Selects the default allocator for the compressed cache for 151 swap pages. 152 The default is 'zbud' for compatibility, however please do 153 read the description of each of the allocators below before 154 making a right choice. 155 156 The selection made here can be overridden by using the kernel 157 command line 'zswap.zpool=' option. 158 159config ZSWAP_ZPOOL_DEFAULT_ZBUD 160 bool "zbud" 161 select ZBUD 162 help 163 Use the zbud allocator as the default allocator. 164 165config ZSWAP_ZPOOL_DEFAULT_Z3FOLD 166 bool "z3fold" 167 select Z3FOLD 168 help 169 Use the z3fold allocator as the default allocator. 170 171config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC 172 bool "zsmalloc" 173 select ZSMALLOC 174 help 175 Use the zsmalloc allocator as the default allocator. 176endchoice 177 178config ZSWAP_ZPOOL_DEFAULT 179 string 180 depends on ZSWAP 181 default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD 182 default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD 183 default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC 184 default "" 185 186config ZBUD 187 tristate "2:1 compression allocator (zbud)" 188 depends on ZSWAP 189 help 190 A special purpose allocator for storing compressed pages. 191 It is designed to store up to two compressed pages per physical 192 page. While this design limits storage density, it has simple and 193 deterministic reclaim properties that make it preferable to a higher 194 density approach when reclaim will be used. 195 196config Z3FOLD 197 tristate "3:1 compression allocator (z3fold)" 198 depends on ZSWAP 199 help 200 A special purpose allocator for storing compressed pages. 201 It is designed to store up to three compressed pages per physical 202 page. It is a ZBUD derivative so the simplicity and determinism are 203 still there. 204 205config ZSMALLOC 206 tristate 207 prompt "N:1 compression allocator (zsmalloc)" if ZSWAP 208 depends on MMU 209 help 210 zsmalloc is a slab-based memory allocator designed to store 211 pages of various compression levels efficiently. It achieves 212 the highest storage density with the least amount of fragmentation. 213 214config ZSMALLOC_STAT 215 bool "Export zsmalloc statistics" 216 depends on ZSMALLOC 217 select DEBUG_FS 218 help 219 This option enables code in the zsmalloc to collect various 220 statistics about what's happening in zsmalloc and exports that 221 information to userspace via debugfs. 222 If unsure, say N. 223 224config ZSMALLOC_CHAIN_SIZE 225 int "Maximum number of physical pages per-zspage" 226 default 8 227 range 4 16 228 depends on ZSMALLOC 229 help 230 This option sets the upper limit on the number of physical pages 231 that a zmalloc page (zspage) can consist of. The optimal zspage 232 chain size is calculated for each size class during the 233 initialization of the pool. 234 235 Changing this option can alter the characteristics of size classes, 236 such as the number of pages per zspage and the number of objects 237 per zspage. This can also result in different configurations of 238 the pool, as zsmalloc merges size classes with similar 239 characteristics. 240 241 For more information, see zsmalloc documentation. 242 243menu "Slab allocator options" 244 245config SLUB 246 def_bool y 247 248config SLUB_TINY 249 bool "Configure for minimal memory footprint" 250 depends on EXPERT 251 select SLAB_MERGE_DEFAULT 252 help 253 Configures the slab allocator in a way to achieve minimal memory 254 footprint, sacrificing scalability, debugging and other features. 255 This is intended only for the smallest system that had used the 256 SLOB allocator and is not recommended for systems with more than 257 16MB RAM. 258 259 If unsure, say N. 260 261config SLAB_MERGE_DEFAULT 262 bool "Allow slab caches to be merged" 263 default y 264 help 265 For reduced kernel memory fragmentation, slab caches can be 266 merged when they share the same size and other characteristics. 267 This carries a risk of kernel heap overflows being able to 268 overwrite objects from merged caches (and more easily control 269 cache layout), which makes such heap attacks easier to exploit 270 by attackers. By keeping caches unmerged, these kinds of exploits 271 can usually only damage objects in the same cache. To disable 272 merging at runtime, "slab_nomerge" can be passed on the kernel 273 command line. 274 275config SLAB_FREELIST_RANDOM 276 bool "Randomize slab freelist" 277 depends on !SLUB_TINY 278 help 279 Randomizes the freelist order used on creating new pages. This 280 security feature reduces the predictability of the kernel slab 281 allocator against heap overflows. 282 283config SLAB_FREELIST_HARDENED 284 bool "Harden slab freelist metadata" 285 depends on !SLUB_TINY 286 help 287 Many kernel heap attacks try to target slab cache metadata and 288 other infrastructure. This options makes minor performance 289 sacrifices to harden the kernel slab allocator against common 290 freelist exploit methods. 291 292config SLUB_STATS 293 default n 294 bool "Enable performance statistics" 295 depends on SYSFS && !SLUB_TINY 296 help 297 The statistics are useful to debug slab allocation behavior in 298 order find ways to optimize the allocator. This should never be 299 enabled for production use since keeping statistics slows down 300 the allocator by a few percentage points. The slabinfo command 301 supports the determination of the most active slabs to figure 302 out which slabs are relevant to a particular load. 303 Try running: slabinfo -DA 304 305config SLUB_CPU_PARTIAL 306 default y 307 depends on SMP && !SLUB_TINY 308 bool "Enable per cpu partial caches" 309 help 310 Per cpu partial caches accelerate objects allocation and freeing 311 that is local to a processor at the price of more indeterminism 312 in the latency of the free. On overflow these caches will be cleared 313 which requires the taking of locks that may cause latency spikes. 314 Typically one would choose no for a realtime system. 315 316config RANDOM_KMALLOC_CACHES 317 default n 318 depends on !SLUB_TINY 319 bool "Randomize slab caches for normal kmalloc" 320 help 321 A hardening feature that creates multiple copies of slab caches for 322 normal kmalloc allocation and makes kmalloc randomly pick one based 323 on code address, which makes the attackers more difficult to spray 324 vulnerable memory objects on the heap for the purpose of exploiting 325 memory vulnerabilities. 326 327 Currently the number of copies is set to 16, a reasonably large value 328 that effectively diverges the memory objects allocated for different 329 subsystems or modules into different caches, at the expense of a 330 limited degree of memory and CPU overhead that relates to hardware and 331 system workload. 332 333endmenu # Slab allocator options 334 335config SHUFFLE_PAGE_ALLOCATOR 336 bool "Page allocator randomization" 337 default SLAB_FREELIST_RANDOM && ACPI_NUMA 338 help 339 Randomization of the page allocator improves the average 340 utilization of a direct-mapped memory-side-cache. See section 341 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI 342 6.2a specification for an example of how a platform advertises 343 the presence of a memory-side-cache. There are also incidental 344 security benefits as it reduces the predictability of page 345 allocations to compliment SLAB_FREELIST_RANDOM, but the 346 default granularity of shuffling on the MAX_PAGE_ORDER i.e, 10th 347 order of pages is selected based on cache utilization benefits 348 on x86. 349 350 While the randomization improves cache utilization it may 351 negatively impact workloads on platforms without a cache. For 352 this reason, by default, the randomization is enabled only 353 after runtime detection of a direct-mapped memory-side-cache. 354 Otherwise, the randomization may be force enabled with the 355 'page_alloc.shuffle' kernel command line parameter. 356 357 Say Y if unsure. 358 359config COMPAT_BRK 360 bool "Disable heap randomization" 361 default y 362 help 363 Randomizing heap placement makes heap exploits harder, but it 364 also breaks ancient binaries (including anything libc5 based). 365 This option changes the bootup default to heap randomization 366 disabled, and can be overridden at runtime by setting 367 /proc/sys/kernel/randomize_va_space to 2. 368 369 On non-ancient distros (post-2000 ones) N is usually a safe choice. 370 371config MMAP_ALLOW_UNINITIALIZED 372 bool "Allow mmapped anonymous memory to be uninitialized" 373 depends on EXPERT && !MMU 374 default n 375 help 376 Normally, and according to the Linux spec, anonymous memory obtained 377 from mmap() has its contents cleared before it is passed to 378 userspace. Enabling this config option allows you to request that 379 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 380 providing a huge performance boost. If this option is not enabled, 381 then the flag will be ignored. 382 383 This is taken advantage of by uClibc's malloc(), and also by 384 ELF-FDPIC binfmt's brk and stack allocator. 385 386 Because of the obvious security issues, this option should only be 387 enabled on embedded devices where you control what is run in 388 userspace. Since that isn't generally a problem on no-MMU systems, 389 it is normally safe to say Y here. 390 391 See Documentation/admin-guide/mm/nommu-mmap.rst for more information. 392 393config SELECT_MEMORY_MODEL 394 def_bool y 395 depends on ARCH_SELECT_MEMORY_MODEL 396 397choice 398 prompt "Memory model" 399 depends on SELECT_MEMORY_MODEL 400 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT 401 default FLATMEM_MANUAL 402 help 403 This option allows you to change some of the ways that 404 Linux manages its memory internally. Most users will 405 only have one option here selected by the architecture 406 configuration. This is normal. 407 408config FLATMEM_MANUAL 409 bool "Flat Memory" 410 depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE 411 help 412 This option is best suited for non-NUMA systems with 413 flat address space. The FLATMEM is the most efficient 414 system in terms of performance and resource consumption 415 and it is the best option for smaller systems. 416 417 For systems that have holes in their physical address 418 spaces and for features like NUMA and memory hotplug, 419 choose "Sparse Memory". 420 421 If unsure, choose this option (Flat Memory) over any other. 422 423config SPARSEMEM_MANUAL 424 bool "Sparse Memory" 425 depends on ARCH_SPARSEMEM_ENABLE 426 help 427 This will be the only option for some systems, including 428 memory hot-plug systems. This is normal. 429 430 This option provides efficient support for systems with 431 holes is their physical address space and allows memory 432 hot-plug and hot-remove. 433 434 If unsure, choose "Flat Memory" over this option. 435 436endchoice 437 438config SPARSEMEM 439 def_bool y 440 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL 441 442config FLATMEM 443 def_bool y 444 depends on !SPARSEMEM || FLATMEM_MANUAL 445 446# 447# SPARSEMEM_EXTREME (which is the default) does some bootmem 448# allocations when sparse_init() is called. If this cannot 449# be done on your architecture, select this option. However, 450# statically allocating the mem_section[] array can potentially 451# consume vast quantities of .bss, so be careful. 452# 453# This option will also potentially produce smaller runtime code 454# with gcc 3.4 and later. 455# 456config SPARSEMEM_STATIC 457 bool 458 459# 460# Architecture platforms which require a two level mem_section in SPARSEMEM 461# must select this option. This is usually for architecture platforms with 462# an extremely sparse physical address space. 463# 464config SPARSEMEM_EXTREME 465 def_bool y 466 depends on SPARSEMEM && !SPARSEMEM_STATIC 467 468config SPARSEMEM_VMEMMAP_ENABLE 469 bool 470 471config SPARSEMEM_VMEMMAP 472 bool "Sparse Memory virtual memmap" 473 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE 474 default y 475 help 476 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise 477 pfn_to_page and page_to_pfn operations. This is the most 478 efficient option when sufficient kernel resources are available. 479# 480# Select this config option from the architecture Kconfig, if it is preferred 481# to enable the feature of HugeTLB/dev_dax vmemmap optimization. 482# 483config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP 484 bool 485 486config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP 487 bool 488 489config HAVE_MEMBLOCK_PHYS_MAP 490 bool 491 492config HAVE_FAST_GUP 493 depends on MMU 494 bool 495 496# Don't discard allocated memory used to track "memory" and "reserved" memblocks 497# after early boot, so it can still be used to test for validity of memory. 498# Also, memblocks are updated with memory hot(un)plug. 499config ARCH_KEEP_MEMBLOCK 500 bool 501 502# Keep arch NUMA mapping infrastructure post-init. 503config NUMA_KEEP_MEMINFO 504 bool 505 506config MEMORY_ISOLATION 507 bool 508 509# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked 510# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via 511# /dev/mem. 512config EXCLUSIVE_SYSTEM_RAM 513 def_bool y 514 depends on !DEVMEM || STRICT_DEVMEM 515 516# 517# Only be set on architectures that have completely implemented memory hotplug 518# feature. If you are not sure, don't touch it. 519# 520config HAVE_BOOTMEM_INFO_NODE 521 def_bool n 522 523config ARCH_ENABLE_MEMORY_HOTPLUG 524 bool 525 526config ARCH_ENABLE_MEMORY_HOTREMOVE 527 bool 528 529# eventually, we can have this option just 'select SPARSEMEM' 530menuconfig MEMORY_HOTPLUG 531 bool "Memory hotplug" 532 select MEMORY_ISOLATION 533 depends on SPARSEMEM 534 depends on ARCH_ENABLE_MEMORY_HOTPLUG 535 depends on 64BIT 536 select NUMA_KEEP_MEMINFO if NUMA 537 538if MEMORY_HOTPLUG 539 540config MEMORY_HOTPLUG_DEFAULT_ONLINE 541 bool "Online the newly added memory blocks by default" 542 depends on MEMORY_HOTPLUG 543 help 544 This option sets the default policy setting for memory hotplug 545 onlining policy (/sys/devices/system/memory/auto_online_blocks) which 546 determines what happens to newly added memory regions. Policy setting 547 can always be changed at runtime. 548 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 549 550 Say Y here if you want all hot-plugged memory blocks to appear in 551 'online' state by default. 552 Say N here if you want the default policy to keep all hot-plugged 553 memory blocks in 'offline' state. 554 555config MEMORY_HOTREMOVE 556 bool "Allow for memory hot remove" 557 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) 558 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE 559 depends on MIGRATION 560 561config MHP_MEMMAP_ON_MEMORY 562 def_bool y 563 depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP 564 depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 565 566endif # MEMORY_HOTPLUG 567 568config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 569 bool 570 571# Heavily threaded applications may benefit from splitting the mm-wide 572# page_table_lock, so that faults on different parts of the user address 573# space can be handled with less contention: split it at this NR_CPUS. 574# Default to 4 for wider testing, though 8 might be more appropriate. 575# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. 576# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. 577# SPARC32 allocates multiple pte tables within a single page, and therefore 578# a per-page lock leads to problems when multiple tables need to be locked 579# at the same time (e.g. copy_page_range()). 580# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. 581# 582config SPLIT_PTLOCK_CPUS 583 int 584 default "999999" if !MMU 585 default "999999" if ARM && !CPU_CACHE_VIPT 586 default "999999" if PARISC && !PA20 587 default "999999" if SPARC32 588 default "4" 589 590config ARCH_ENABLE_SPLIT_PMD_PTLOCK 591 bool 592 593# 594# support for memory balloon 595config MEMORY_BALLOON 596 bool 597 598# 599# support for memory balloon compaction 600config BALLOON_COMPACTION 601 bool "Allow for balloon memory compaction/migration" 602 def_bool y 603 depends on COMPACTION && MEMORY_BALLOON 604 help 605 Memory fragmentation introduced by ballooning might reduce 606 significantly the number of 2MB contiguous memory blocks that can be 607 used within a guest, thus imposing performance penalties associated 608 with the reduced number of transparent huge pages that could be used 609 by the guest workload. Allowing the compaction & migration for memory 610 pages enlisted as being part of memory balloon devices avoids the 611 scenario aforementioned and helps improving memory defragmentation. 612 613# 614# support for memory compaction 615config COMPACTION 616 bool "Allow for memory compaction" 617 def_bool y 618 select MIGRATION 619 depends on MMU 620 help 621 Compaction is the only memory management component to form 622 high order (larger physically contiguous) memory blocks 623 reliably. The page allocator relies on compaction heavily and 624 the lack of the feature can lead to unexpected OOM killer 625 invocations for high order memory requests. You shouldn't 626 disable this option unless there really is a strong reason for 627 it and then we would be really interested to hear about that at 628 linux-mm@kvack.org. 629 630config COMPACT_UNEVICTABLE_DEFAULT 631 int 632 depends on COMPACTION 633 default 0 if PREEMPT_RT 634 default 1 635 636# 637# support for free page reporting 638config PAGE_REPORTING 639 bool "Free page reporting" 640 def_bool n 641 help 642 Free page reporting allows for the incremental acquisition of 643 free pages from the buddy allocator for the purpose of reporting 644 those pages to another entity, such as a hypervisor, so that the 645 memory can be freed within the host for other uses. 646 647# 648# support for page migration 649# 650config MIGRATION 651 bool "Page migration" 652 def_bool y 653 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU 654 help 655 Allows the migration of the physical location of pages of processes 656 while the virtual addresses are not changed. This is useful in 657 two situations. The first is on NUMA systems to put pages nearer 658 to the processors accessing. The second is when allocating huge 659 pages as migration can relocate pages to satisfy a huge page 660 allocation instead of reclaiming. 661 662config DEVICE_MIGRATION 663 def_bool MIGRATION && ZONE_DEVICE 664 665config ARCH_ENABLE_HUGEPAGE_MIGRATION 666 bool 667 668config ARCH_ENABLE_THP_MIGRATION 669 bool 670 671config HUGETLB_PAGE_SIZE_VARIABLE 672 def_bool n 673 help 674 Allows the pageblock_order value to be dynamic instead of just standard 675 HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available 676 on a platform. 677 678 Note that the pageblock_order cannot exceed MAX_PAGE_ORDER and will be 679 clamped down to MAX_PAGE_ORDER. 680 681config CONTIG_ALLOC 682 def_bool (MEMORY_ISOLATION && COMPACTION) || CMA 683 684config PCP_BATCH_SCALE_MAX 685 int "Maximum scale factor of PCP (Per-CPU pageset) batch allocate/free" 686 default 5 687 range 0 6 688 help 689 In page allocator, PCP (Per-CPU pageset) is refilled and drained in 690 batches. The batch number is scaled automatically to improve page 691 allocation/free throughput. But too large scale factor may hurt 692 latency. This option sets the upper limit of scale factor to limit 693 the maximum latency. 694 695config PHYS_ADDR_T_64BIT 696 def_bool 64BIT 697 698config BOUNCE 699 bool "Enable bounce buffers" 700 default y 701 depends on BLOCK && MMU && HIGHMEM 702 help 703 Enable bounce buffers for devices that cannot access the full range of 704 memory available to the CPU. Enabled by default when HIGHMEM is 705 selected, but you may say n to override this. 706 707config MMU_NOTIFIER 708 bool 709 select INTERVAL_TREE 710 711config KSM 712 bool "Enable KSM for page merging" 713 depends on MMU 714 select XXHASH 715 help 716 Enable Kernel Samepage Merging: KSM periodically scans those areas 717 of an application's address space that an app has advised may be 718 mergeable. When it finds pages of identical content, it replaces 719 the many instances by a single page with that content, so 720 saving memory until one or another app needs to modify the content. 721 Recommended for use with KVM, or with other duplicative applications. 722 See Documentation/mm/ksm.rst for more information: KSM is inactive 723 until a program has madvised that an area is MADV_MERGEABLE, and 724 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). 725 726config DEFAULT_MMAP_MIN_ADDR 727 int "Low address space to protect from user allocation" 728 depends on MMU 729 default 4096 730 help 731 This is the portion of low virtual memory which should be protected 732 from userspace allocation. Keeping a user from writing to low pages 733 can help reduce the impact of kernel NULL pointer bugs. 734 735 For most ppc64 and x86 users with lots of address space 736 a value of 65536 is reasonable and should cause no problems. 737 On arm and other archs it should not be higher than 32768. 738 Programs which use vm86 functionality or have some need to map 739 this low address space will need CAP_SYS_RAWIO or disable this 740 protection by setting the value to 0. 741 742 This value can be changed after boot using the 743 /proc/sys/vm/mmap_min_addr tunable. 744 745config ARCH_SUPPORTS_MEMORY_FAILURE 746 bool 747 748config MEMORY_FAILURE 749 depends on MMU 750 depends on ARCH_SUPPORTS_MEMORY_FAILURE 751 bool "Enable recovery from hardware memory errors" 752 select MEMORY_ISOLATION 753 select RAS 754 help 755 Enables code to recover from some memory failures on systems 756 with MCA recovery. This allows a system to continue running 757 even when some of its memory has uncorrected errors. This requires 758 special hardware support and typically ECC memory. 759 760config HWPOISON_INJECT 761 tristate "HWPoison pages injector" 762 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS 763 select PROC_PAGE_MONITOR 764 765config NOMMU_INITIAL_TRIM_EXCESS 766 int "Turn on mmap() excess space trimming before booting" 767 depends on !MMU 768 default 1 769 help 770 The NOMMU mmap() frequently needs to allocate large contiguous chunks 771 of memory on which to store mappings, but it can only ask the system 772 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 773 more than it requires. To deal with this, mmap() is able to trim off 774 the excess and return it to the allocator. 775 776 If trimming is enabled, the excess is trimmed off and returned to the 777 system allocator, which can cause extra fragmentation, particularly 778 if there are a lot of transient processes. 779 780 If trimming is disabled, the excess is kept, but not used, which for 781 long-term mappings means that the space is wasted. 782 783 Trimming can be dynamically controlled through a sysctl option 784 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 785 excess pages there must be before trimming should occur, or zero if 786 no trimming is to occur. 787 788 This option specifies the initial value of this option. The default 789 of 1 says that all excess pages should be trimmed. 790 791 See Documentation/admin-guide/mm/nommu-mmap.rst for more information. 792 793config ARCH_WANT_GENERAL_HUGETLB 794 bool 795 796config ARCH_WANTS_THP_SWAP 797 def_bool n 798 799menuconfig TRANSPARENT_HUGEPAGE 800 bool "Transparent Hugepage Support" 801 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT 802 select COMPACTION 803 select XARRAY_MULTI 804 help 805 Transparent Hugepages allows the kernel to use huge pages and 806 huge tlb transparently to the applications whenever possible. 807 This feature can improve computing performance to certain 808 applications by speeding up page faults during memory 809 allocation, by reducing the number of tlb misses and by speeding 810 up the pagetable walking. 811 812 If memory constrained on embedded, you may want to say N. 813 814if TRANSPARENT_HUGEPAGE 815 816choice 817 prompt "Transparent Hugepage Support sysfs defaults" 818 depends on TRANSPARENT_HUGEPAGE 819 default TRANSPARENT_HUGEPAGE_ALWAYS 820 help 821 Selects the sysfs defaults for Transparent Hugepage Support. 822 823 config TRANSPARENT_HUGEPAGE_ALWAYS 824 bool "always" 825 help 826 Enabling Transparent Hugepage always, can increase the 827 memory footprint of applications without a guaranteed 828 benefit but it will work automatically for all applications. 829 830 config TRANSPARENT_HUGEPAGE_MADVISE 831 bool "madvise" 832 help 833 Enabling Transparent Hugepage madvise, will only provide a 834 performance improvement benefit to the applications using 835 madvise(MADV_HUGEPAGE) but it won't risk to increase the 836 memory footprint of applications without a guaranteed 837 benefit. 838 839 config TRANSPARENT_HUGEPAGE_NEVER 840 bool "never" 841 help 842 Disable Transparent Hugepage by default. It can still be 843 enabled at runtime via sysfs. 844endchoice 845 846config THP_SWAP 847 def_bool y 848 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT 849 help 850 Swap transparent huge pages in one piece, without splitting. 851 XXX: For now, swap cluster backing transparent huge page 852 will be split after swapout. 853 854 For selection by architectures with reasonable THP sizes. 855 856config READ_ONLY_THP_FOR_FS 857 bool "Read-only THP for filesystems (EXPERIMENTAL)" 858 depends on TRANSPARENT_HUGEPAGE && SHMEM 859 860 help 861 Allow khugepaged to put read-only file-backed pages in THP. 862 863 This is marked experimental because it is a new feature. Write 864 support of file THPs will be developed in the next few release 865 cycles. 866 867endif # TRANSPARENT_HUGEPAGE 868 869# 870# UP and nommu archs use km based percpu allocator 871# 872config NEED_PER_CPU_KM 873 depends on !SMP || !MMU 874 bool 875 default y 876 877config NEED_PER_CPU_EMBED_FIRST_CHUNK 878 bool 879 880config NEED_PER_CPU_PAGE_FIRST_CHUNK 881 bool 882 883config USE_PERCPU_NUMA_NODE_ID 884 bool 885 886config HAVE_SETUP_PER_CPU_AREA 887 bool 888 889config CMA 890 bool "Contiguous Memory Allocator" 891 depends on MMU 892 select MIGRATION 893 select MEMORY_ISOLATION 894 help 895 This enables the Contiguous Memory Allocator which allows other 896 subsystems to allocate big physically-contiguous blocks of memory. 897 CMA reserves a region of memory and allows only movable pages to 898 be allocated from it. This way, the kernel can use the memory for 899 pagecache and when a subsystem requests for contiguous area, the 900 allocated pages are migrated away to serve the contiguous request. 901 902 If unsure, say "n". 903 904config CMA_DEBUG 905 bool "CMA debug messages (DEVELOPMENT)" 906 depends on DEBUG_KERNEL && CMA 907 help 908 Turns on debug messages in CMA. This produces KERN_DEBUG 909 messages for every CMA call as well as various messages while 910 processing calls such as dma_alloc_from_contiguous(). 911 This option does not affect warning and error messages. 912 913config CMA_DEBUGFS 914 bool "CMA debugfs interface" 915 depends on CMA && DEBUG_FS 916 help 917 Turns on the DebugFS interface for CMA. 918 919config CMA_SYSFS 920 bool "CMA information through sysfs interface" 921 depends on CMA && SYSFS 922 help 923 This option exposes some sysfs attributes to get information 924 from CMA. 925 926config CMA_AREAS 927 int "Maximum count of the CMA areas" 928 depends on CMA 929 default 19 if NUMA 930 default 7 931 help 932 CMA allows to create CMA areas for particular purpose, mainly, 933 used as device private area. This parameter sets the maximum 934 number of CMA area in the system. 935 936 If unsure, leave the default value "7" in UMA and "19" in NUMA. 937 938config MEM_SOFT_DIRTY 939 bool "Track memory changes" 940 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS 941 select PROC_PAGE_MONITOR 942 help 943 This option enables memory changes tracking by introducing a 944 soft-dirty bit on pte-s. This bit it set when someone writes 945 into a page just as regular dirty bit, but unlike the latter 946 it can be cleared by hands. 947 948 See Documentation/admin-guide/mm/soft-dirty.rst for more details. 949 950config GENERIC_EARLY_IOREMAP 951 bool 952 953config STACK_MAX_DEFAULT_SIZE_MB 954 int "Default maximum user stack size for 32-bit processes (MB)" 955 default 100 956 range 8 2048 957 depends on STACK_GROWSUP && (!64BIT || COMPAT) 958 help 959 This is the maximum stack size in Megabytes in the VM layout of 32-bit 960 user processes when the stack grows upwards (currently only on parisc 961 arch) when the RLIMIT_STACK hard limit is unlimited. 962 963 A sane initial value is 100 MB. 964 965config DEFERRED_STRUCT_PAGE_INIT 966 bool "Defer initialisation of struct pages to kthreads" 967 depends on SPARSEMEM 968 depends on !NEED_PER_CPU_KM 969 depends on 64BIT 970 select PADATA 971 help 972 Ordinarily all struct pages are initialised during early boot in a 973 single thread. On very large machines this can take a considerable 974 amount of time. If this option is set, large machines will bring up 975 a subset of memmap at boot and then initialise the rest in parallel. 976 This has a potential performance impact on tasks running early in the 977 lifetime of the system until these kthreads finish the 978 initialisation. 979 980config PAGE_IDLE_FLAG 981 bool 982 select PAGE_EXTENSION if !64BIT 983 help 984 This adds PG_idle and PG_young flags to 'struct page'. PTE Accessed 985 bit writers can set the state of the bit in the flags so that PTE 986 Accessed bit readers may avoid disturbance. 987 988config IDLE_PAGE_TRACKING 989 bool "Enable idle page tracking" 990 depends on SYSFS && MMU 991 select PAGE_IDLE_FLAG 992 help 993 This feature allows to estimate the amount of user pages that have 994 not been touched during a given period of time. This information can 995 be useful to tune memory cgroup limits and/or for job placement 996 within a compute cluster. 997 998 See Documentation/admin-guide/mm/idle_page_tracking.rst for 999 more details. 1000 1001config ARCH_HAS_CACHE_LINE_SIZE 1002 bool 1003 1004config ARCH_HAS_CURRENT_STACK_POINTER 1005 bool 1006 help 1007 In support of HARDENED_USERCOPY performing stack variable lifetime 1008 checking, an architecture-agnostic way to find the stack pointer 1009 is needed. Once an architecture defines an unsigned long global 1010 register alias named "current_stack_pointer", this config can be 1011 selected. 1012 1013config ARCH_HAS_PTE_DEVMAP 1014 bool 1015 1016config ARCH_HAS_ZONE_DMA_SET 1017 bool 1018 1019config ZONE_DMA 1020 bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET 1021 default y if ARM64 || X86 1022 1023config ZONE_DMA32 1024 bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET 1025 depends on !X86_32 1026 default y if ARM64 1027 1028config ZONE_DEVICE 1029 bool "Device memory (pmem, HMM, etc...) hotplug support" 1030 depends on MEMORY_HOTPLUG 1031 depends on MEMORY_HOTREMOVE 1032 depends on SPARSEMEM_VMEMMAP 1033 depends on ARCH_HAS_PTE_DEVMAP 1034 select XARRAY_MULTI 1035 1036 help 1037 Device memory hotplug support allows for establishing pmem, 1038 or other device driver discovered memory regions, in the 1039 memmap. This allows pfn_to_page() lookups of otherwise 1040 "device-physical" addresses which is needed for using a DAX 1041 mapping in an O_DIRECT operation, among other things. 1042 1043 If FS_DAX is enabled, then say Y. 1044 1045# 1046# Helpers to mirror range of the CPU page tables of a process into device page 1047# tables. 1048# 1049config HMM_MIRROR 1050 bool 1051 depends on MMU 1052 1053config GET_FREE_REGION 1054 depends on SPARSEMEM 1055 bool 1056 1057config DEVICE_PRIVATE 1058 bool "Unaddressable device memory (GPU memory, ...)" 1059 depends on ZONE_DEVICE 1060 select GET_FREE_REGION 1061 1062 help 1063 Allows creation of struct pages to represent unaddressable device 1064 memory; i.e., memory that is only accessible from the device (or 1065 group of devices). You likely also want to select HMM_MIRROR. 1066 1067config VMAP_PFN 1068 bool 1069 1070config ARCH_USES_HIGH_VMA_FLAGS 1071 bool 1072config ARCH_HAS_PKEYS 1073 bool 1074 1075config ARCH_USES_PG_ARCH_X 1076 bool 1077 help 1078 Enable the definition of PG_arch_x page flags with x > 1. Only 1079 suitable for 64-bit architectures with CONFIG_FLATMEM or 1080 CONFIG_SPARSEMEM_VMEMMAP enabled, otherwise there may not be 1081 enough room for additional bits in page->flags. 1082 1083config VM_EVENT_COUNTERS 1084 default y 1085 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1086 help 1087 VM event counters are needed for event counts to be shown. 1088 This option allows the disabling of the VM event counters 1089 on EXPERT systems. /proc/vmstat will only show page counts 1090 if VM event counters are disabled. 1091 1092config PERCPU_STATS 1093 bool "Collect percpu memory statistics" 1094 help 1095 This feature collects and exposes statistics via debugfs. The 1096 information includes global and per chunk statistics, which can 1097 be used to help understand percpu memory usage. 1098 1099config GUP_TEST 1100 bool "Enable infrastructure for get_user_pages()-related unit tests" 1101 depends on DEBUG_FS 1102 help 1103 Provides /sys/kernel/debug/gup_test, which in turn provides a way 1104 to make ioctl calls that can launch kernel-based unit tests for 1105 the get_user_pages*() and pin_user_pages*() family of API calls. 1106 1107 These tests include benchmark testing of the _fast variants of 1108 get_user_pages*() and pin_user_pages*(), as well as smoke tests of 1109 the non-_fast variants. 1110 1111 There is also a sub-test that allows running dump_page() on any 1112 of up to eight pages (selected by command line args) within the 1113 range of user-space addresses. These pages are either pinned via 1114 pin_user_pages*(), or pinned via get_user_pages*(), as specified 1115 by other command line arguments. 1116 1117 See tools/testing/selftests/mm/gup_test.c 1118 1119comment "GUP_TEST needs to have DEBUG_FS enabled" 1120 depends on !GUP_TEST && !DEBUG_FS 1121 1122config GUP_GET_PXX_LOW_HIGH 1123 bool 1124 1125config DMAPOOL_TEST 1126 tristate "Enable a module to run time tests on dma_pool" 1127 depends on HAS_DMA 1128 help 1129 Provides a test module that will allocate and free many blocks of 1130 various sizes and report how long it takes. This is intended to 1131 provide a consistent way to measure how changes to the 1132 dma_pool_alloc/free routines affect performance. 1133 1134config ARCH_HAS_PTE_SPECIAL 1135 bool 1136 1137# 1138# Some architectures require a special hugepage directory format that is 1139# required to support multiple hugepage sizes. For example a4fe3ce76 1140# "powerpc/mm: Allow more flexible layouts for hugepage pagetables" 1141# introduced it on powerpc. This allows for a more flexible hugepage 1142# pagetable layouts. 1143# 1144config ARCH_HAS_HUGEPD 1145 bool 1146 1147config MAPPING_DIRTY_HELPERS 1148 bool 1149 1150config KMAP_LOCAL 1151 bool 1152 1153config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY 1154 bool 1155 1156# struct io_mapping based helper. Selected by drivers that need them 1157config IO_MAPPING 1158 bool 1159 1160config MEMFD_CREATE 1161 bool "Enable memfd_create() system call" if EXPERT 1162 1163config SECRETMEM 1164 default y 1165 bool "Enable memfd_secret() system call" if EXPERT 1166 depends on ARCH_HAS_SET_DIRECT_MAP 1167 help 1168 Enable the memfd_secret() system call with the ability to create 1169 memory areas visible only in the context of the owning process and 1170 not mapped to other processes and other kernel page tables. 1171 1172config ANON_VMA_NAME 1173 bool "Anonymous VMA name support" 1174 depends on PROC_FS && ADVISE_SYSCALLS && MMU 1175 1176 help 1177 Allow naming anonymous virtual memory areas. 1178 1179 This feature allows assigning names to virtual memory areas. Assigned 1180 names can be later retrieved from /proc/pid/maps and /proc/pid/smaps 1181 and help identifying individual anonymous memory areas. 1182 Assigning a name to anonymous virtual memory area might prevent that 1183 area from being merged with adjacent virtual memory areas due to the 1184 difference in their name. 1185 1186config HAVE_ARCH_USERFAULTFD_WP 1187 bool 1188 help 1189 Arch has userfaultfd write protection support 1190 1191config HAVE_ARCH_USERFAULTFD_MINOR 1192 bool 1193 help 1194 Arch has userfaultfd minor fault support 1195 1196menuconfig USERFAULTFD 1197 bool "Enable userfaultfd() system call" 1198 depends on MMU 1199 help 1200 Enable the userfaultfd() system call that allows to intercept and 1201 handle page faults in userland. 1202 1203if USERFAULTFD 1204config PTE_MARKER_UFFD_WP 1205 bool "Userfaultfd write protection support for shmem/hugetlbfs" 1206 default y 1207 depends on HAVE_ARCH_USERFAULTFD_WP 1208 1209 help 1210 Allows to create marker PTEs for userfaultfd write protection 1211 purposes. It is required to enable userfaultfd write protection on 1212 file-backed memory types like shmem and hugetlbfs. 1213endif # USERFAULTFD 1214 1215# multi-gen LRU { 1216config LRU_GEN 1217 bool "Multi-Gen LRU" 1218 depends on MMU 1219 # make sure folio->flags has enough spare bits 1220 depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP 1221 help 1222 A high performance LRU implementation to overcommit memory. See 1223 Documentation/admin-guide/mm/multigen_lru.rst for details. 1224 1225config LRU_GEN_ENABLED 1226 bool "Enable by default" 1227 depends on LRU_GEN 1228 help 1229 This option enables the multi-gen LRU by default. 1230 1231config LRU_GEN_STATS 1232 bool "Full stats for debugging" 1233 depends on LRU_GEN 1234 help 1235 Do not enable this option unless you plan to look at historical stats 1236 from evicted generations for debugging purpose. 1237 1238 This option has a per-memcg and per-node memory overhead. 1239 1240config LRU_GEN_WALKS_MMU 1241 def_bool y 1242 depends on LRU_GEN && ARCH_HAS_HW_PTE_YOUNG 1243# } 1244 1245config ARCH_SUPPORTS_PER_VMA_LOCK 1246 def_bool n 1247 1248config PER_VMA_LOCK 1249 def_bool y 1250 depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP 1251 help 1252 Allow per-vma locking during page fault handling. 1253 1254 This feature allows locking each virtual memory area separately when 1255 handling page faults instead of taking mmap_lock. 1256 1257config LOCK_MM_AND_FIND_VMA 1258 bool 1259 depends on !STACK_GROWSUP 1260 1261config IOMMU_MM_DATA 1262 bool 1263 1264source "mm/damon/Kconfig" 1265 1266endmenu 1267