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 12menuconfig SWAP 13 bool "Support for paging of anonymous memory (swap)" 14 depends on MMU && BLOCK && !ARCH_NO_SWAP 15 default y 16 help 17 This option allows you to choose whether you want to have support 18 for so called swap devices or swap files in your kernel that are 19 used to provide more virtual memory than the actual RAM present 20 in your computer. If unsure say Y. 21 22config ZSWAP 23 bool "Compressed cache for swap pages" 24 depends on SWAP 25 select CRYPTO 26 select ZSMALLOC 27 help 28 A lightweight compressed cache for swap pages. It takes 29 pages that are in the process of being swapped out and attempts to 30 compress them into a dynamically allocated RAM-based memory pool. 31 This can result in a significant I/O reduction on swap device and, 32 in the case where decompressing from RAM is faster than swap device 33 reads, can also improve workload performance. 34 35config ZSWAP_DEFAULT_ON 36 bool "Enable the compressed cache for swap pages by default" 37 depends on ZSWAP 38 help 39 If selected, the compressed cache for swap pages will be enabled 40 at boot, otherwise it will be disabled. 41 42 The selection made here can be overridden by using the kernel 43 command line 'zswap.enabled=' option. 44 45config ZSWAP_SHRINKER_DEFAULT_ON 46 bool "Shrink the zswap pool on memory pressure" 47 depends on ZSWAP 48 default n 49 help 50 If selected, the zswap shrinker will be enabled, and the pages 51 stored in the zswap pool will become available for reclaim (i.e 52 written back to the backing swap device) on memory pressure. 53 54 This means that zswap writeback could happen even if the pool is 55 not yet full, or the cgroup zswap limit has not been reached, 56 reducing the chance that cold pages will reside in the zswap pool 57 and consume memory indefinitely. 58 59choice 60 prompt "Default compressor" 61 depends on ZSWAP 62 default ZSWAP_COMPRESSOR_DEFAULT_LZO 63 help 64 Selects the default compression algorithm for the compressed cache 65 for swap pages. 66 67 For an overview what kind of performance can be expected from 68 a particular compression algorithm please refer to the benchmarks 69 available at the following LWN page: 70 https://lwn.net/Articles/751795/ 71 72 If in doubt, select 'LZO'. 73 74 The selection made here can be overridden by using the kernel 75 command line 'zswap.compressor=' option. 76 77config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE 78 bool "Deflate" 79 select CRYPTO_DEFLATE 80 help 81 Use the Deflate algorithm as the default compression algorithm. 82 83config ZSWAP_COMPRESSOR_DEFAULT_LZO 84 bool "LZO" 85 select CRYPTO_LZO 86 help 87 Use the LZO algorithm as the default compression algorithm. 88 89config ZSWAP_COMPRESSOR_DEFAULT_842 90 bool "842" 91 select CRYPTO_842 92 help 93 Use the 842 algorithm as the default compression algorithm. 94 95config ZSWAP_COMPRESSOR_DEFAULT_LZ4 96 bool "LZ4" 97 select CRYPTO_LZ4 98 help 99 Use the LZ4 algorithm as the default compression algorithm. 100 101config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC 102 bool "LZ4HC" 103 select CRYPTO_LZ4HC 104 help 105 Use the LZ4HC algorithm as the default compression algorithm. 106 107config ZSWAP_COMPRESSOR_DEFAULT_ZSTD 108 bool "zstd" 109 select CRYPTO_ZSTD 110 help 111 Use the zstd algorithm as the default compression algorithm. 112endchoice 113 114config ZSWAP_COMPRESSOR_DEFAULT 115 string 116 depends on ZSWAP 117 default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE 118 default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO 119 default "842" if ZSWAP_COMPRESSOR_DEFAULT_842 120 default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4 121 default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC 122 default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD 123 default "" 124 125config ZSMALLOC 126 tristate 127 128if ZSMALLOC 129 130menu "Zsmalloc allocator options" 131 depends on ZSMALLOC 132 133comment "Zsmalloc is a common backend allocator for zswap & zram" 134 135config ZSMALLOC_STAT 136 bool "Export zsmalloc statistics" 137 select DEBUG_FS 138 help 139 This option enables code in the zsmalloc to collect various 140 statistics about what's happening in zsmalloc and exports that 141 information to userspace via debugfs. 142 If unsure, say N. 143 144config ZSMALLOC_CHAIN_SIZE 145 int "Maximum number of physical pages per-zspage" 146 default 8 147 range 4 16 148 help 149 This option sets the upper limit on the number of physical pages 150 that a zmalloc page (zspage) can consist of. The optimal zspage 151 chain size is calculated for each size class during the 152 initialization of the pool. 153 154 Changing this option can alter the characteristics of size classes, 155 such as the number of pages per zspage and the number of objects 156 per zspage. This can also result in different configurations of 157 the pool, as zsmalloc merges size classes with similar 158 characteristics. 159 160 For more information, see zsmalloc documentation. 161 162endmenu 163 164endif 165 166menu "Slab allocator options" 167 168config SLUB 169 def_bool y 170 select IRQ_WORK 171 172config KVFREE_RCU_BATCHED 173 def_bool y 174 depends on !SLUB_TINY && !TINY_RCU 175 176config SLUB_TINY 177 bool "Configure for minimal memory footprint" 178 depends on EXPERT && !COMPILE_TEST 179 select SLAB_MERGE_DEFAULT 180 help 181 Configures the slab allocator in a way to achieve minimal memory 182 footprint, sacrificing scalability, debugging and other features. 183 This is intended only for the smallest system that had used the 184 SLOB allocator and is not recommended for systems with more than 185 16MB RAM. 186 187 If unsure, say N. 188 189config SLAB_MERGE_DEFAULT 190 bool "Allow slab caches to be merged" 191 default y 192 help 193 For reduced kernel memory fragmentation, slab caches can be 194 merged when they share the same size and other characteristics. 195 This carries a risk of kernel heap overflows being able to 196 overwrite objects from merged caches (and more easily control 197 cache layout), which makes such heap attacks easier to exploit 198 by attackers. By keeping caches unmerged, these kinds of exploits 199 can usually only damage objects in the same cache. To disable 200 merging at runtime, "slab_nomerge" can be passed on the kernel 201 command line. 202 203config SLAB_FREELIST_RANDOM 204 bool "Randomize slab freelist" 205 depends on !SLUB_TINY 206 help 207 Randomizes the freelist order used on creating new pages. This 208 security feature reduces the predictability of the kernel slab 209 allocator against heap overflows. 210 211config SLAB_FREELIST_HARDENED 212 bool "Harden slab freelist metadata" 213 depends on !SLUB_TINY 214 help 215 Many kernel heap attacks try to target slab cache metadata and 216 other infrastructure. This options makes minor performance 217 sacrifices to harden the kernel slab allocator against common 218 freelist exploit methods. 219 220config SLAB_BUCKETS 221 bool "Support allocation from separate kmalloc buckets" 222 depends on !SLUB_TINY 223 default SLAB_FREELIST_HARDENED 224 help 225 Kernel heap attacks frequently depend on being able to create 226 specifically-sized allocations with user-controlled contents 227 that will be allocated into the same kmalloc bucket as a 228 target object. To avoid sharing these allocation buckets, 229 provide an explicitly separated set of buckets to be used for 230 user-controlled allocations. This may very slightly increase 231 memory fragmentation, though in practice it's only a handful 232 of extra pages since the bulk of user-controlled allocations 233 are relatively long-lived. 234 235 If unsure, say Y. 236 237config SLUB_STATS 238 default n 239 bool "Enable performance statistics" 240 depends on SYSFS && !SLUB_TINY 241 help 242 The statistics are useful to debug slab allocation behavior in 243 order find ways to optimize the allocator. This should never be 244 enabled for production use since keeping statistics slows down 245 the allocator by a few percentage points. The slabinfo command 246 supports the determination of the most active slabs to figure 247 out which slabs are relevant to a particular load. 248 Try running: slabinfo -DA 249 250config SLUB_CPU_PARTIAL 251 default y 252 depends on SMP && !SLUB_TINY 253 bool "Enable per cpu partial caches" 254 help 255 Per cpu partial caches accelerate objects allocation and freeing 256 that is local to a processor at the price of more indeterminism 257 in the latency of the free. On overflow these caches will be cleared 258 which requires the taking of locks that may cause latency spikes. 259 Typically one would choose no for a realtime system. 260 261config RANDOM_KMALLOC_CACHES 262 default n 263 depends on !SLUB_TINY 264 bool "Randomize slab caches for normal kmalloc" 265 help 266 A hardening feature that creates multiple copies of slab caches for 267 normal kmalloc allocation and makes kmalloc randomly pick one based 268 on code address, which makes the attackers more difficult to spray 269 vulnerable memory objects on the heap for the purpose of exploiting 270 memory vulnerabilities. 271 272 Currently the number of copies is set to 16, a reasonably large value 273 that effectively diverges the memory objects allocated for different 274 subsystems or modules into different caches, at the expense of a 275 limited degree of memory and CPU overhead that relates to hardware and 276 system workload. 277 278endmenu # Slab allocator options 279 280config SHUFFLE_PAGE_ALLOCATOR 281 bool "Page allocator randomization" 282 default SLAB_FREELIST_RANDOM && ACPI_NUMA 283 help 284 Randomization of the page allocator improves the average 285 utilization of a direct-mapped memory-side-cache. See section 286 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI 287 6.2a specification for an example of how a platform advertises 288 the presence of a memory-side-cache. There are also incidental 289 security benefits as it reduces the predictability of page 290 allocations to compliment SLAB_FREELIST_RANDOM, but the 291 default granularity of shuffling on the MAX_PAGE_ORDER i.e, 10th 292 order of pages is selected based on cache utilization benefits 293 on x86. 294 295 While the randomization improves cache utilization it may 296 negatively impact workloads on platforms without a cache. For 297 this reason, by default, the randomization is not enabled even 298 if SHUFFLE_PAGE_ALLOCATOR=y. The randomization may be force enabled 299 with the 'page_alloc.shuffle' kernel command line parameter. 300 301 Say Y if unsure. 302 303config COMPAT_BRK 304 bool "Disable heap randomization" 305 default y 306 help 307 Randomizing heap placement makes heap exploits harder, but it 308 also breaks ancient binaries (including anything libc5 based). 309 This option changes the bootup default to heap randomization 310 disabled, and can be overridden at runtime by setting 311 /proc/sys/kernel/randomize_va_space to 2. 312 313 On non-ancient distros (post-2000 ones) N is usually a safe choice. 314 315config MMAP_ALLOW_UNINITIALIZED 316 bool "Allow mmapped anonymous memory to be uninitialized" 317 depends on EXPERT && !MMU 318 default n 319 help 320 Normally, and according to the Linux spec, anonymous memory obtained 321 from mmap() has its contents cleared before it is passed to 322 userspace. Enabling this config option allows you to request that 323 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 324 providing a huge performance boost. If this option is not enabled, 325 then the flag will be ignored. 326 327 This is taken advantage of by uClibc's malloc(), and also by 328 ELF-FDPIC binfmt's brk and stack allocator. 329 330 Because of the obvious security issues, this option should only be 331 enabled on embedded devices where you control what is run in 332 userspace. Since that isn't generally a problem on no-MMU systems, 333 it is normally safe to say Y here. 334 335 See Documentation/admin-guide/mm/nommu-mmap.rst for more information. 336 337config SELECT_MEMORY_MODEL 338 def_bool y 339 depends on ARCH_SELECT_MEMORY_MODEL 340 341choice 342 prompt "Memory model" 343 depends on SELECT_MEMORY_MODEL 344 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT 345 default FLATMEM_MANUAL 346 help 347 This option allows you to change some of the ways that 348 Linux manages its memory internally. Most users will 349 only have one option here selected by the architecture 350 configuration. This is normal. 351 352config FLATMEM_MANUAL 353 bool "Flat Memory" 354 depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE 355 help 356 This option is best suited for non-NUMA systems with 357 flat address space. The FLATMEM is the most efficient 358 system in terms of performance and resource consumption 359 and it is the best option for smaller systems. 360 361 For systems that have holes in their physical address 362 spaces and for features like NUMA and memory hotplug, 363 choose "Sparse Memory". 364 365 If unsure, choose this option (Flat Memory) over any other. 366 367config SPARSEMEM_MANUAL 368 bool "Sparse Memory" 369 depends on ARCH_SPARSEMEM_ENABLE 370 help 371 This will be the only option for some systems, including 372 memory hot-plug systems. This is normal. 373 374 This option provides efficient support for systems with 375 holes is their physical address space and allows memory 376 hot-plug and hot-remove. 377 378 If unsure, choose "Flat Memory" over this option. 379 380endchoice 381 382config SPARSEMEM 383 def_bool y 384 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL 385 386config FLATMEM 387 def_bool y 388 depends on !SPARSEMEM || FLATMEM_MANUAL 389 390# 391# SPARSEMEM_EXTREME (which is the default) does some bootmem 392# allocations when sparse_init() is called. If this cannot 393# be done on your architecture, select this option. However, 394# statically allocating the mem_section[] array can potentially 395# consume vast quantities of .bss, so be careful. 396# 397# This option will also potentially produce smaller runtime code 398# with gcc 3.4 and later. 399# 400config SPARSEMEM_STATIC 401 bool 402 403# 404# Architecture platforms which require a two level mem_section in SPARSEMEM 405# must select this option. This is usually for architecture platforms with 406# an extremely sparse physical address space. 407# 408config SPARSEMEM_EXTREME 409 def_bool y 410 depends on SPARSEMEM && !SPARSEMEM_STATIC 411 412config SPARSEMEM_VMEMMAP_ENABLE 413 bool 414 415config SPARSEMEM_VMEMMAP 416 def_bool y 417 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE 418 help 419 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise 420 pfn_to_page and page_to_pfn operations. This is the most 421 efficient option when sufficient kernel resources are available. 422 423config SPARSEMEM_VMEMMAP_PREINIT 424 bool 425# 426# Select this config option from the architecture Kconfig, if it is preferred 427# to enable the feature of HugeTLB/dev_dax vmemmap optimization. 428# 429config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP 430 bool 431 432config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP 433 bool 434 435config ARCH_WANT_HUGETLB_VMEMMAP_PREINIT 436 bool 437 438config HAVE_MEMBLOCK_PHYS_MAP 439 bool 440 441config HAVE_GUP_FAST 442 depends on MMU 443 bool 444 445# Enable memblock support for scratch memory which is needed for kexec handover 446config MEMBLOCK_KHO_SCRATCH 447 bool 448 449# Don't discard allocated memory used to track "memory" and "reserved" memblocks 450# after early boot, so it can still be used to test for validity of memory. 451# Also, memblocks are updated with memory hot(un)plug. 452config ARCH_KEEP_MEMBLOCK 453 bool 454 455# Keep arch NUMA mapping infrastructure post-init. 456config NUMA_KEEP_MEMINFO 457 bool 458 459config MEMORY_ISOLATION 460 bool 461 462# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked 463# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via 464# /dev/mem. 465config EXCLUSIVE_SYSTEM_RAM 466 def_bool y 467 depends on !DEVMEM || STRICT_DEVMEM 468 469# 470# Only be set on architectures that have completely implemented memory hotplug 471# feature. If you are not sure, don't touch it. 472# 473config HAVE_BOOTMEM_INFO_NODE 474 def_bool n 475 476config ARCH_ENABLE_MEMORY_HOTPLUG 477 bool 478 479config ARCH_ENABLE_MEMORY_HOTREMOVE 480 bool 481 482# eventually, we can have this option just 'select SPARSEMEM' 483menuconfig MEMORY_HOTPLUG 484 bool "Memory hotplug" 485 select MEMORY_ISOLATION 486 depends on SPARSEMEM 487 depends on ARCH_ENABLE_MEMORY_HOTPLUG 488 depends on 64BIT 489 select NUMA_KEEP_MEMINFO if NUMA 490 491if MEMORY_HOTPLUG 492 493choice 494 prompt "Memory Hotplug Default Online Type" 495 default MHP_DEFAULT_ONLINE_TYPE_OFFLINE 496 help 497 Default memory type for hotplugged memory. 498 499 This option sets the default policy setting for memory hotplug 500 onlining policy (/sys/devices/system/memory/auto_online_blocks) which 501 determines what happens to newly added memory regions. Policy setting 502 can always be changed at runtime. 503 504 The default is 'offline'. 505 506 Select offline to defer onlining to drivers and user policy. 507 Select auto to let the kernel choose what zones to utilize. 508 Select online_kernel to generally allow kernel usage of this memory. 509 Select online_movable to generally disallow kernel usage of this memory. 510 511 Example kernel usage would be page structs and page tables. 512 513 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 514 515config MHP_DEFAULT_ONLINE_TYPE_OFFLINE 516 bool "offline" 517 help 518 Hotplugged memory will not be onlined by default. 519 Choose this for systems with drivers and user policy that 520 handle onlining of hotplug memory policy. 521 522config MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO 523 bool "auto" 524 help 525 Select this if you want the kernel to automatically online 526 hotplugged memory into the zone it thinks is reasonable. 527 This memory may be utilized for kernel data. 528 529config MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL 530 bool "kernel" 531 help 532 Select this if you want the kernel to automatically online 533 hotplugged memory into a zone capable of being used for kernel 534 data. This typically means ZONE_NORMAL. 535 536config MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE 537 bool "movable" 538 help 539 Select this if you want the kernel to automatically online 540 hotplug memory into ZONE_MOVABLE. This memory will generally 541 not be utilized for kernel data. 542 543 This should only be used when the admin knows sufficient 544 ZONE_NORMAL memory is available to describe hotplug memory, 545 otherwise hotplug memory may fail to online. For example, 546 sufficient kernel-capable memory (ZONE_NORMAL) must be 547 available to allocate page structs to describe ZONE_MOVABLE. 548 549endchoice 550 551config MEMORY_HOTREMOVE 552 bool "Allow for memory hot remove" 553 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) 554 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE 555 depends on MIGRATION 556 557config MHP_MEMMAP_ON_MEMORY 558 def_bool y 559 depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP 560 depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 561 562endif # MEMORY_HOTPLUG 563 564config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 565 bool 566 567# Heavily threaded applications may benefit from splitting the mm-wide 568# page_table_lock, so that faults on different parts of the user address 569# space can be handled with less contention: split it at this NR_CPUS. 570# Default to 4 for wider testing, though 8 might be more appropriate. 571# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. 572# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. 573# SPARC32 allocates multiple pte tables within a single page, and therefore 574# a per-page lock leads to problems when multiple tables need to be locked 575# at the same time (e.g. copy_page_range()). 576# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. 577# 578config SPLIT_PTE_PTLOCKS 579 def_bool y 580 depends on MMU 581 depends on SMP 582 depends on NR_CPUS >= 4 583 depends on !ARM || CPU_CACHE_VIPT 584 depends on !PARISC || PA20 585 depends on !SPARC32 586 587config ARCH_ENABLE_SPLIT_PMD_PTLOCK 588 bool 589 590config SPLIT_PMD_PTLOCKS 591 def_bool y 592 depends on SPLIT_PTE_PTLOCKS && ARCH_ENABLE_SPLIT_PMD_PTLOCK 593 594# 595# support for memory balloon 596config MEMORY_BALLOON 597 bool 598 599# 600# support for memory balloon compaction 601config BALLOON_COMPACTION 602 bool "Allow for balloon memory compaction/migration" 603 default y 604 depends on COMPACTION && MEMORY_BALLOON 605 help 606 Memory fragmentation introduced by ballooning might reduce 607 significantly the number of 2MB contiguous memory blocks that can be 608 used within a guest, thus imposing performance penalties associated 609 with the reduced number of transparent huge pages that could be used 610 by the guest workload. Allowing the compaction & migration for memory 611 pages enlisted as being part of memory balloon devices avoids the 612 scenario aforementioned and helps improving memory defragmentation. 613 614# 615# support for memory compaction 616config COMPACTION 617 bool "Allow for memory compaction" 618 default y 619 select MIGRATION 620 depends on MMU 621 help 622 Compaction is the only memory management component to form 623 high order (larger physically contiguous) memory blocks 624 reliably. The page allocator relies on compaction heavily and 625 the lack of the feature can lead to unexpected OOM killer 626 invocations for high order memory requests. You shouldn't 627 disable this option unless there really is a strong reason for 628 it and then we would be really interested to hear about that at 629 linux-mm@kvack.org. 630 631config COMPACT_UNEVICTABLE_DEFAULT 632 int 633 depends on COMPACTION 634 default 0 if PREEMPT_RT 635 default 1 636 637# 638# support for free page reporting 639config PAGE_REPORTING 640 bool "Free page reporting" 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 default 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 MMU_NOTIFIER 699 bool 700 select INTERVAL_TREE 701 702config KSM 703 bool "Enable KSM for page merging" 704 depends on MMU 705 select XXHASH 706 help 707 Enable Kernel Samepage Merging: KSM periodically scans those areas 708 of an application's address space that an app has advised may be 709 mergeable. When it finds pages of identical content, it replaces 710 the many instances by a single page with that content, so 711 saving memory until one or another app needs to modify the content. 712 Recommended for use with KVM, or with other duplicative applications. 713 See Documentation/mm/ksm.rst for more information: KSM is inactive 714 until a program has madvised that an area is MADV_MERGEABLE, and 715 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). 716 717config DEFAULT_MMAP_MIN_ADDR 718 int "Low address space to protect from user allocation" 719 depends on MMU 720 default 4096 721 help 722 This is the portion of low virtual memory which should be protected 723 from userspace allocation. Keeping a user from writing to low pages 724 can help reduce the impact of kernel NULL pointer bugs. 725 726 For most arm64, ppc64 and x86 users with lots of address space 727 a value of 65536 is reasonable and should cause no problems. 728 On arm and other archs it should not be higher than 32768. 729 Programs which use vm86 functionality or have some need to map 730 this low address space will need CAP_SYS_RAWIO or disable this 731 protection by setting the value to 0. 732 733 This value can be changed after boot using the 734 /proc/sys/vm/mmap_min_addr tunable. 735 736config ARCH_SUPPORTS_MEMORY_FAILURE 737 bool 738 739config MEMORY_FAILURE 740 depends on MMU 741 depends on ARCH_SUPPORTS_MEMORY_FAILURE 742 bool "Enable recovery from hardware memory errors" 743 select INTERVAL_TREE 744 help 745 Enables code to recover from some memory failures on systems 746 with MCA recovery. This allows a system to continue running 747 even when some of its memory has uncorrected errors. This requires 748 special hardware support and typically ECC memory. 749 750config HWPOISON_INJECT 751 tristate "HWPoison pages injector" 752 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS 753 select PROC_PAGE_MONITOR 754 755config NOMMU_INITIAL_TRIM_EXCESS 756 int "Turn on mmap() excess space trimming before booting" 757 depends on !MMU 758 default 1 759 help 760 The NOMMU mmap() frequently needs to allocate large contiguous chunks 761 of memory on which to store mappings, but it can only ask the system 762 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 763 more than it requires. To deal with this, mmap() is able to trim off 764 the excess and return it to the allocator. 765 766 If trimming is enabled, the excess is trimmed off and returned to the 767 system allocator, which can cause extra fragmentation, particularly 768 if there are a lot of transient processes. 769 770 If trimming is disabled, the excess is kept, but not used, which for 771 long-term mappings means that the space is wasted. 772 773 Trimming can be dynamically controlled through a sysctl option 774 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 775 excess pages there must be before trimming should occur, or zero if 776 no trimming is to occur. 777 778 This option specifies the initial value of this option. The default 779 of 1 says that all excess pages should be trimmed. 780 781 See Documentation/admin-guide/mm/nommu-mmap.rst for more information. 782 783config ARCH_WANT_GENERAL_HUGETLB 784 bool 785 786config ARCH_WANTS_THP_SWAP 787 def_bool n 788 789config PERSISTENT_HUGE_ZERO_FOLIO 790 bool "Allocate a PMD sized folio for zeroing" 791 depends on TRANSPARENT_HUGEPAGE 792 help 793 Enable this option to reduce the runtime refcounting overhead 794 of the huge zero folio and expand the places in the kernel 795 that can use huge zero folios. For instance, block I/O benefits 796 from access to large folios for zeroing memory. 797 798 With this option enabled, the huge zero folio is allocated 799 once and never freed. One full huge page's worth of memory shall 800 be used. 801 802 Say Y if your system has lots of memory. Say N if you are 803 memory constrained. 804 805config MM_ID 806 def_bool n 807 808menuconfig TRANSPARENT_HUGEPAGE 809 bool "Transparent Hugepage Support" 810 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT 811 select COMPACTION 812 select XARRAY_MULTI 813 select MM_ID 814 help 815 Transparent Hugepages allows the kernel to use huge pages and 816 huge tlb transparently to the applications whenever possible. 817 This feature can improve computing performance to certain 818 applications by speeding up page faults during memory 819 allocation, by reducing the number of tlb misses and by speeding 820 up the pagetable walking. 821 822 If memory constrained on embedded, you may want to say N. 823 824if TRANSPARENT_HUGEPAGE 825 826choice 827 prompt "Transparent Hugepage Support sysfs defaults" 828 depends on TRANSPARENT_HUGEPAGE 829 default TRANSPARENT_HUGEPAGE_ALWAYS 830 help 831 Selects the sysfs defaults for Transparent Hugepage Support. 832 833 config TRANSPARENT_HUGEPAGE_ALWAYS 834 bool "always" 835 help 836 Enabling Transparent Hugepage always, can increase the 837 memory footprint of applications without a guaranteed 838 benefit but it will work automatically for all applications. 839 840 config TRANSPARENT_HUGEPAGE_MADVISE 841 bool "madvise" 842 help 843 Enabling Transparent Hugepage madvise, will only provide a 844 performance improvement benefit to the applications using 845 madvise(MADV_HUGEPAGE) but it won't risk to increase the 846 memory footprint of applications without a guaranteed 847 benefit. 848 849 config TRANSPARENT_HUGEPAGE_NEVER 850 bool "never" 851 help 852 Disable Transparent Hugepage by default. It can still be 853 enabled at runtime via sysfs. 854endchoice 855 856choice 857 prompt "Shmem hugepage allocation defaults" 858 depends on TRANSPARENT_HUGEPAGE 859 default TRANSPARENT_HUGEPAGE_SHMEM_HUGE_NEVER 860 help 861 Selects the hugepage allocation policy defaults for 862 the internal shmem mount. 863 864 The selection made here can be overridden by using the kernel 865 command line 'transparent_hugepage_shmem=' option. 866 867 config TRANSPARENT_HUGEPAGE_SHMEM_HUGE_NEVER 868 bool "never" 869 help 870 Disable hugepage allocation for shmem mount by default. It can 871 still be enabled with the kernel command line 872 'transparent_hugepage_shmem=' option or at runtime via sysfs 873 knob. Note that madvise(MADV_COLLAPSE) can still cause 874 transparent huge pages to be obtained even if this mode is 875 specified. 876 877 config TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ALWAYS 878 bool "always" 879 help 880 Always attempt to allocate hugepage for shmem mount, can 881 increase the memory footprint of applications without a 882 guaranteed benefit but it will work automatically for all 883 applications. 884 885 config TRANSPARENT_HUGEPAGE_SHMEM_HUGE_WITHIN_SIZE 886 bool "within_size" 887 help 888 Enable hugepage allocation for shmem mount if the allocation 889 will be fully within the i_size. This configuration also takes 890 into account any madvise(MADV_HUGEPAGE) hints that may be 891 provided by the applications. 892 893 config TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ADVISE 894 bool "advise" 895 help 896 Enable hugepage allocation for the shmem mount exclusively when 897 applications supply the madvise(MADV_HUGEPAGE) hint. 898 This ensures that hugepages are used only in response to explicit 899 requests from applications. 900endchoice 901 902choice 903 prompt "Tmpfs hugepage allocation defaults" 904 depends on TRANSPARENT_HUGEPAGE 905 default TRANSPARENT_HUGEPAGE_TMPFS_HUGE_NEVER 906 help 907 Selects the hugepage allocation policy defaults for 908 the tmpfs mount. 909 910 The selection made here can be overridden by using the kernel 911 command line 'transparent_hugepage_tmpfs=' option. 912 913 config TRANSPARENT_HUGEPAGE_TMPFS_HUGE_NEVER 914 bool "never" 915 help 916 Disable hugepage allocation for tmpfs mount by default. It can 917 still be enabled with the kernel command line 918 'transparent_hugepage_tmpfs=' option. Note that 919 madvise(MADV_COLLAPSE) can still cause transparent huge pages 920 to be obtained even if this mode is specified. 921 922 config TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ALWAYS 923 bool "always" 924 help 925 Always attempt to allocate hugepage for tmpfs mount, can 926 increase the memory footprint of applications without a 927 guaranteed benefit but it will work automatically for all 928 applications. 929 930 config TRANSPARENT_HUGEPAGE_TMPFS_HUGE_WITHIN_SIZE 931 bool "within_size" 932 help 933 Enable hugepage allocation for tmpfs mount if the allocation 934 will be fully within the i_size. This configuration also takes 935 into account any madvise(MADV_HUGEPAGE) hints that may be 936 provided by the applications. 937 938 config TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ADVISE 939 bool "advise" 940 help 941 Enable hugepage allocation for the tmpfs mount exclusively when 942 applications supply the madvise(MADV_HUGEPAGE) hint. 943 This ensures that hugepages are used only in response to explicit 944 requests from applications. 945endchoice 946 947config THP_SWAP 948 def_bool y 949 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT 950 help 951 Swap transparent huge pages in one piece, without splitting. 952 XXX: For now, swap cluster backing transparent huge page 953 will be split after swapout. 954 955 For selection by architectures with reasonable THP sizes. 956 957config READ_ONLY_THP_FOR_FS 958 bool "Read-only THP for filesystems (EXPERIMENTAL)" 959 depends on TRANSPARENT_HUGEPAGE 960 961 help 962 Allow khugepaged to put read-only file-backed pages in THP. 963 964 This is marked experimental because it is a new feature. Write 965 support of file THPs will be developed in the next few release 966 cycles. 967 968config NO_PAGE_MAPCOUNT 969 bool "No per-page mapcount (EXPERIMENTAL)" 970 help 971 Do not maintain per-page mapcounts for pages part of larger 972 allocations, such as transparent huge pages. 973 974 When this config option is enabled, some interfaces that relied on 975 this information will rely on less-precise per-allocation information 976 instead: for example, using the average per-page mapcount in such 977 a large allocation instead of the per-page mapcount. 978 979 EXPERIMENTAL because the impact of some changes is still unclear. 980 981endif # TRANSPARENT_HUGEPAGE 982 983# simple helper to make the code a bit easier to read 984config PAGE_MAPCOUNT 985 def_bool !NO_PAGE_MAPCOUNT 986 987# 988# The architecture supports pgtable leaves that is larger than PAGE_SIZE 989# 990config PGTABLE_HAS_HUGE_LEAVES 991 def_bool TRANSPARENT_HUGEPAGE || HUGETLB_PAGE 992 993# 994# We can end up creating gigantic folio. 995# 996config HAVE_GIGANTIC_FOLIOS 997 def_bool (HUGETLB_PAGE && ARCH_HAS_GIGANTIC_PAGE) || \ 998 (ZONE_DEVICE && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) 999 1000config ASYNC_KERNEL_PGTABLE_FREE 1001 def_bool n 1002 1003# TODO: Allow to be enabled without THP 1004config ARCH_SUPPORTS_HUGE_PFNMAP 1005 def_bool n 1006 depends on TRANSPARENT_HUGEPAGE 1007 1008config ARCH_SUPPORTS_PMD_PFNMAP 1009 def_bool y 1010 depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE 1011 1012config ARCH_SUPPORTS_PUD_PFNMAP 1013 def_bool y 1014 depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1015 1016# 1017# Architectures that always use weak definitions for percpu 1018# variables in modules should set this. 1019# 1020config ARCH_MODULE_NEEDS_WEAK_PER_CPU 1021 bool 1022 1023# 1024# UP and nommu archs use km based percpu allocator 1025# 1026config NEED_PER_CPU_KM 1027 depends on !SMP || !MMU 1028 bool 1029 default y 1030 1031config NEED_PER_CPU_EMBED_FIRST_CHUNK 1032 bool 1033 1034config NEED_PER_CPU_PAGE_FIRST_CHUNK 1035 bool 1036 1037config USE_PERCPU_NUMA_NODE_ID 1038 bool 1039 1040config HAVE_SETUP_PER_CPU_AREA 1041 bool 1042 1043config CMA 1044 bool "Contiguous Memory Allocator" 1045 depends on MMU 1046 select MIGRATION 1047 select MEMORY_ISOLATION 1048 help 1049 This enables the Contiguous Memory Allocator which allows other 1050 subsystems to allocate big physically-contiguous blocks of memory. 1051 CMA reserves a region of memory and allows only movable pages to 1052 be allocated from it. This way, the kernel can use the memory for 1053 pagecache and when a subsystem requests for contiguous area, the 1054 allocated pages are migrated away to serve the contiguous request. 1055 1056 If unsure, say "n". 1057 1058config CMA_DEBUGFS 1059 bool "CMA debugfs interface" 1060 depends on CMA && DEBUG_FS 1061 help 1062 Turns on the DebugFS interface for CMA. 1063 1064config CMA_SYSFS 1065 bool "CMA information through sysfs interface" 1066 depends on CMA && SYSFS 1067 help 1068 This option exposes some sysfs attributes to get information 1069 from CMA. 1070 1071config CMA_AREAS 1072 int "Maximum count of the CMA areas" 1073 depends on CMA 1074 default 20 if NUMA 1075 default 8 1076 help 1077 CMA allows to create CMA areas for particular purpose, mainly, 1078 used as device private area. This parameter sets the maximum 1079 number of CMA area in the system. 1080 1081 If unsure, leave the default value "8" in UMA and "20" in NUMA. 1082 1083# 1084# Select this config option from the architecture Kconfig, if available, to set 1085# the max page order for physically contiguous allocations. 1086# 1087config ARCH_FORCE_MAX_ORDER 1088 int 1089 1090# 1091# When ARCH_FORCE_MAX_ORDER is not defined, 1092# the default page block order is MAX_PAGE_ORDER (10) as per 1093# include/linux/mmzone.h. 1094# 1095config PAGE_BLOCK_MAX_ORDER 1096 int "Page Block Order Upper Limit" 1097 range 1 10 if ARCH_FORCE_MAX_ORDER = 0 1098 default 10 if ARCH_FORCE_MAX_ORDER = 0 1099 range 1 ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER != 0 1100 default ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER != 0 1101 help 1102 The page block order refers to the power of two number of pages that 1103 are physically contiguous and can have a migrate type associated to 1104 them. The maximum size of the page block order is at least limited by 1105 ARCH_FORCE_MAX_ORDER/MAX_PAGE_ORDER. 1106 1107 This config adds a new upper limit of default page block 1108 order when the page block order is required to be smaller than 1109 ARCH_FORCE_MAX_ORDER/MAX_PAGE_ORDER or other limits 1110 (see include/linux/pageblock-flags.h for details). 1111 1112 Reducing pageblock order can negatively impact THP generation 1113 success rate. If your workloads use THP heavily, please use this 1114 option with caution. 1115 1116 Don't change if unsure. 1117 1118config MEM_SOFT_DIRTY 1119 bool "Track memory changes" 1120 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS 1121 select PROC_PAGE_MONITOR 1122 help 1123 This option enables memory changes tracking by introducing a 1124 soft-dirty bit on pte-s. This bit it set when someone writes 1125 into a page just as regular dirty bit, but unlike the latter 1126 it can be cleared by hands. 1127 1128 See Documentation/admin-guide/mm/soft-dirty.rst for more details. 1129 1130config GENERIC_EARLY_IOREMAP 1131 bool 1132 1133config STACK_MAX_DEFAULT_SIZE_MB 1134 int "Default maximum user stack size for 32-bit processes (MB)" 1135 default 100 1136 range 8 2048 1137 depends on STACK_GROWSUP && (!64BIT || COMPAT) 1138 help 1139 This is the maximum stack size in Megabytes in the VM layout of 32-bit 1140 user processes when the stack grows upwards (currently only on parisc 1141 arch) when the RLIMIT_STACK hard limit is unlimited. 1142 1143 A sane initial value is 100 MB. 1144 1145config DEFERRED_STRUCT_PAGE_INIT 1146 bool "Defer initialisation of struct pages to kthreads" 1147 depends on SPARSEMEM 1148 depends on !NEED_PER_CPU_KM 1149 depends on 64BIT 1150 depends on !KMSAN 1151 select PADATA 1152 help 1153 Ordinarily all struct pages are initialised during early boot in a 1154 single thread. On very large machines this can take a considerable 1155 amount of time. If this option is set, large machines will bring up 1156 a subset of memmap at boot and then initialise the rest in parallel. 1157 This has a potential performance impact on tasks running early in the 1158 lifetime of the system until these kthreads finish the 1159 initialisation. 1160 1161config PAGE_IDLE_FLAG 1162 bool 1163 select PAGE_EXTENSION if !64BIT 1164 help 1165 This adds PG_idle and PG_young flags to 'struct page'. PTE Accessed 1166 bit writers can set the state of the bit in the flags so that PTE 1167 Accessed bit readers may avoid disturbance. 1168 1169config IDLE_PAGE_TRACKING 1170 bool "Enable idle page tracking" 1171 depends on SYSFS && MMU 1172 select PAGE_IDLE_FLAG 1173 help 1174 This feature allows to estimate the amount of user pages that have 1175 not been touched during a given period of time. This information can 1176 be useful to tune memory cgroup limits and/or for job placement 1177 within a compute cluster. 1178 1179 See Documentation/admin-guide/mm/idle_page_tracking.rst for 1180 more details. 1181 1182# Architectures which implement cpu_dcache_is_aliasing() to query 1183# whether the data caches are aliased (VIVT or VIPT with dcache 1184# aliasing) need to select this. 1185config ARCH_HAS_CPU_CACHE_ALIASING 1186 bool 1187 1188config ARCH_HAS_CACHE_LINE_SIZE 1189 bool 1190 1191config ARCH_HAS_CURRENT_STACK_POINTER 1192 bool 1193 help 1194 In support of HARDENED_USERCOPY performing stack variable lifetime 1195 checking, an architecture-agnostic way to find the stack pointer 1196 is needed. Once an architecture defines an unsigned long global 1197 register alias named "current_stack_pointer", this config can be 1198 selected. 1199 1200config ARCH_HAS_ZONE_DMA_SET 1201 bool 1202 1203config ZONE_DMA 1204 bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET 1205 default y if ARM64 || X86 1206 1207config ZONE_DMA32 1208 bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET 1209 depends on !X86_32 1210 default y if ARM64 1211 1212config ZONE_DEVICE 1213 bool "Device memory (pmem, HMM, etc...) hotplug support" 1214 depends on MEMORY_HOTPLUG 1215 depends on MEMORY_HOTREMOVE 1216 depends on SPARSEMEM_VMEMMAP 1217 select XARRAY_MULTI 1218 1219 help 1220 Device memory hotplug support allows for establishing pmem, 1221 or other device driver discovered memory regions, in the 1222 memmap. This allows pfn_to_page() lookups of otherwise 1223 "device-physical" addresses which is needed for using a DAX 1224 mapping in an O_DIRECT operation, among other things. 1225 1226 If FS_DAX is enabled, then say Y. 1227 1228# 1229# Helpers to mirror range of the CPU page tables of a process into device page 1230# tables. 1231# 1232config HMM_MIRROR 1233 bool 1234 depends on MMU 1235 1236config GET_FREE_REGION 1237 bool 1238 1239config DEVICE_PRIVATE 1240 bool "Unaddressable device memory (GPU memory, ...)" 1241 depends on ZONE_DEVICE 1242 select GET_FREE_REGION 1243 1244 help 1245 Allows creation of struct pages to represent unaddressable device 1246 memory; i.e., memory that is only accessible from the device (or 1247 group of devices). You likely also want to select HMM_MIRROR. 1248 1249config VMAP_PFN 1250 bool 1251 1252config ARCH_USES_HIGH_VMA_FLAGS 1253 bool 1254config ARCH_HAS_PKEYS 1255 bool 1256 1257config ARCH_USES_PG_ARCH_2 1258 bool 1259config ARCH_USES_PG_ARCH_3 1260 bool 1261 1262config VM_EVENT_COUNTERS 1263 default y 1264 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1265 help 1266 VM event counters are needed for event counts to be shown. 1267 This option allows the disabling of the VM event counters 1268 on EXPERT systems. /proc/vmstat will only show page counts 1269 if VM event counters are disabled. 1270 1271config PERCPU_STATS 1272 bool "Collect percpu memory statistics" 1273 help 1274 This feature collects and exposes statistics via debugfs. The 1275 information includes global and per chunk statistics, which can 1276 be used to help understand percpu memory usage. 1277 1278config GUP_TEST 1279 bool "Enable infrastructure for get_user_pages()-related unit tests" 1280 depends on DEBUG_FS 1281 help 1282 Provides /sys/kernel/debug/gup_test, which in turn provides a way 1283 to make ioctl calls that can launch kernel-based unit tests for 1284 the get_user_pages*() and pin_user_pages*() family of API calls. 1285 1286 These tests include benchmark testing of the _fast variants of 1287 get_user_pages*() and pin_user_pages*(), as well as smoke tests of 1288 the non-_fast variants. 1289 1290 There is also a sub-test that allows running dump_page() on any 1291 of up to eight pages (selected by command line args) within the 1292 range of user-space addresses. These pages are either pinned via 1293 pin_user_pages*(), or pinned via get_user_pages*(), as specified 1294 by other command line arguments. 1295 1296 See tools/testing/selftests/mm/gup_test.c 1297 1298comment "GUP_TEST needs to have DEBUG_FS enabled" 1299 depends on !GUP_TEST && !DEBUG_FS 1300 1301config GUP_GET_PXX_LOW_HIGH 1302 bool 1303 1304config DMAPOOL_TEST 1305 tristate "Enable a module to run time tests on dma_pool" 1306 depends on HAS_DMA 1307 help 1308 Provides a test module that will allocate and free many blocks of 1309 various sizes and report how long it takes. This is intended to 1310 provide a consistent way to measure how changes to the 1311 dma_pool_alloc/free routines affect performance. 1312 1313config ARCH_HAS_PTE_SPECIAL 1314 bool 1315 1316config MAPPING_DIRTY_HELPERS 1317 bool 1318 1319config KMAP_LOCAL 1320 bool 1321 1322config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY 1323 bool 1324 1325config MEMFD_CREATE 1326 bool "Enable memfd_create() system call" if EXPERT 1327 1328config SECRETMEM 1329 default y 1330 bool "Enable memfd_secret() system call" if EXPERT 1331 depends on ARCH_HAS_SET_DIRECT_MAP 1332 help 1333 Enable the memfd_secret() system call with the ability to create 1334 memory areas visible only in the context of the owning process and 1335 not mapped to other processes and other kernel page tables. 1336 1337config ANON_VMA_NAME 1338 bool "Anonymous VMA name support" 1339 depends on PROC_FS && ADVISE_SYSCALLS && MMU 1340 1341 help 1342 Allow naming anonymous virtual memory areas. 1343 1344 This feature allows assigning names to virtual memory areas. Assigned 1345 names can be later retrieved from /proc/pid/maps and /proc/pid/smaps 1346 and help identifying individual anonymous memory areas. 1347 Assigning a name to anonymous virtual memory area might prevent that 1348 area from being merged with adjacent virtual memory areas due to the 1349 difference in their name. 1350 1351config HAVE_ARCH_USERFAULTFD_WP 1352 bool 1353 help 1354 Arch has userfaultfd write protection support 1355 1356config HAVE_ARCH_USERFAULTFD_MINOR 1357 bool 1358 help 1359 Arch has userfaultfd minor fault support 1360 1361menuconfig USERFAULTFD 1362 bool "Enable userfaultfd() system call" 1363 depends on MMU 1364 help 1365 Enable the userfaultfd() system call that allows to intercept and 1366 handle page faults in userland. 1367 1368if USERFAULTFD 1369config PTE_MARKER_UFFD_WP 1370 bool "Userfaultfd write protection support for shmem/hugetlbfs" 1371 default y 1372 depends on HAVE_ARCH_USERFAULTFD_WP 1373 1374 help 1375 Allows to create marker PTEs for userfaultfd write protection 1376 purposes. It is required to enable userfaultfd write protection on 1377 file-backed memory types like shmem and hugetlbfs. 1378endif # USERFAULTFD 1379 1380# multi-gen LRU { 1381config LRU_GEN 1382 bool "Multi-Gen LRU" 1383 depends on MMU 1384 # make sure folio->flags has enough spare bits 1385 depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP 1386 help 1387 A high performance LRU implementation to overcommit memory. See 1388 Documentation/admin-guide/mm/multigen_lru.rst for details. 1389 1390config LRU_GEN_ENABLED 1391 bool "Enable by default" 1392 depends on LRU_GEN 1393 help 1394 This option enables the multi-gen LRU by default. 1395 1396config LRU_GEN_STATS 1397 bool "Full stats for debugging" 1398 depends on LRU_GEN 1399 help 1400 Do not enable this option unless you plan to look at historical stats 1401 from evicted generations for debugging purpose. 1402 1403 This option has a per-memcg and per-node memory overhead. 1404 1405config LRU_GEN_WALKS_MMU 1406 def_bool y 1407 depends on LRU_GEN && ARCH_HAS_HW_PTE_YOUNG 1408# } 1409 1410config ARCH_SUPPORTS_PER_VMA_LOCK 1411 def_bool n 1412 1413config PER_VMA_LOCK 1414 def_bool y 1415 depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP 1416 help 1417 Allow per-vma locking during page fault handling. 1418 1419 This feature allows locking each virtual memory area separately when 1420 handling page faults instead of taking mmap_lock. 1421 1422config LOCK_MM_AND_FIND_VMA 1423 bool 1424 depends on !STACK_GROWSUP 1425 1426config IOMMU_MM_DATA 1427 bool 1428 1429config EXECMEM 1430 bool 1431 1432config NUMA_MEMBLKS 1433 bool 1434 1435config NUMA_EMU 1436 bool "NUMA emulation" 1437 depends on NUMA_MEMBLKS 1438 depends on X86 || GENERIC_ARCH_NUMA 1439 help 1440 Enable NUMA emulation. A flat machine will be split 1441 into virtual nodes when booted with "numa=fake=N", where N is the 1442 number of nodes. This is only useful for debugging. 1443 1444config ARCH_HAS_USER_SHADOW_STACK 1445 bool 1446 help 1447 The architecture has hardware support for userspace shadow call 1448 stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss). 1449 1450config ARCH_SUPPORTS_PT_RECLAIM 1451 def_bool n 1452 1453config PT_RECLAIM 1454 bool "reclaim empty user page table pages" 1455 default y 1456 depends on ARCH_SUPPORTS_PT_RECLAIM && MMU && SMP 1457 select MMU_GATHER_RCU_TABLE_FREE 1458 help 1459 Try to reclaim empty user page table pages in paths other than munmap 1460 and exit_mmap path. 1461 1462 Note: now only empty user PTE page table pages will be reclaimed. 1463 1464config FIND_NORMAL_PAGE 1465 def_bool n 1466 1467source "mm/damon/Kconfig" 1468 1469endmenu 1470