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