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 RANDOM_KMALLOC_CACHES 251 default n 252 depends on !SLUB_TINY 253 bool "Randomize slab caches for normal kmalloc" 254 help 255 A hardening feature that creates multiple copies of slab caches for 256 normal kmalloc allocation and makes kmalloc randomly pick one based 257 on code address, which makes the attackers more difficult to spray 258 vulnerable memory objects on the heap for the purpose of exploiting 259 memory vulnerabilities. 260 261 Currently the number of copies is set to 16, a reasonably large value 262 that effectively diverges the memory objects allocated for different 263 subsystems or modules into different caches, at the expense of a 264 limited degree of memory and CPU overhead that relates to hardware and 265 system workload. 266 267endmenu # Slab allocator options 268 269config SHUFFLE_PAGE_ALLOCATOR 270 bool "Page allocator randomization" 271 default SLAB_FREELIST_RANDOM && ACPI_NUMA 272 help 273 Randomization of the page allocator improves the average 274 utilization of a direct-mapped memory-side-cache. See section 275 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI 276 6.2a specification for an example of how a platform advertises 277 the presence of a memory-side-cache. There are also incidental 278 security benefits as it reduces the predictability of page 279 allocations to compliment SLAB_FREELIST_RANDOM, but the 280 default granularity of shuffling on the MAX_PAGE_ORDER i.e, 10th 281 order of pages is selected based on cache utilization benefits 282 on x86. 283 284 While the randomization improves cache utilization it may 285 negatively impact workloads on platforms without a cache. For 286 this reason, by default, the randomization is not enabled even 287 if SHUFFLE_PAGE_ALLOCATOR=y. The randomization may be force enabled 288 with the 'page_alloc.shuffle' kernel command line parameter. 289 290 Say Y if unsure. 291 292config COMPAT_BRK 293 bool "Disable heap randomization" 294 default y 295 help 296 Randomizing heap placement makes heap exploits harder, but it 297 also breaks ancient binaries (including anything libc5 based). 298 This option changes the bootup default to heap randomization 299 disabled, and can be overridden at runtime by setting 300 /proc/sys/kernel/randomize_va_space to 2. 301 302 On non-ancient distros (post-2000 ones) N is usually a safe choice. 303 304config MMAP_ALLOW_UNINITIALIZED 305 bool "Allow mmapped anonymous memory to be uninitialized" 306 depends on EXPERT && !MMU 307 default n 308 help 309 Normally, and according to the Linux spec, anonymous memory obtained 310 from mmap() has its contents cleared before it is passed to 311 userspace. Enabling this config option allows you to request that 312 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus 313 providing a huge performance boost. If this option is not enabled, 314 then the flag will be ignored. 315 316 This is taken advantage of by uClibc's malloc(), and also by 317 ELF-FDPIC binfmt's brk and stack allocator. 318 319 Because of the obvious security issues, this option should only be 320 enabled on embedded devices where you control what is run in 321 userspace. Since that isn't generally a problem on no-MMU systems, 322 it is normally safe to say Y here. 323 324 See Documentation/admin-guide/mm/nommu-mmap.rst for more information. 325 326config SELECT_MEMORY_MODEL 327 def_bool y 328 depends on ARCH_SELECT_MEMORY_MODEL 329 330choice 331 prompt "Memory model" 332 depends on SELECT_MEMORY_MODEL 333 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT 334 default FLATMEM_MANUAL 335 help 336 This option allows you to change some of the ways that 337 Linux manages its memory internally. Most users will 338 only have one option here selected by the architecture 339 configuration. This is normal. 340 341config FLATMEM_MANUAL 342 bool "Flat Memory" 343 depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE 344 help 345 This option is best suited for non-NUMA systems with 346 flat address space. The FLATMEM is the most efficient 347 system in terms of performance and resource consumption 348 and it is the best option for smaller systems. 349 350 For systems that have holes in their physical address 351 spaces and for features like NUMA and memory hotplug, 352 choose "Sparse Memory". 353 354 If unsure, choose this option (Flat Memory) over any other. 355 356config SPARSEMEM_MANUAL 357 bool "Sparse Memory" 358 depends on ARCH_SPARSEMEM_ENABLE 359 help 360 This will be the only option for some systems, including 361 memory hot-plug systems. This is normal. 362 363 This option provides efficient support for systems with 364 holes is their physical address space and allows memory 365 hot-plug and hot-remove. 366 367 If unsure, choose "Flat Memory" over this option. 368 369endchoice 370 371config SPARSEMEM 372 def_bool y 373 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL 374 375config FLATMEM 376 def_bool y 377 depends on !SPARSEMEM || FLATMEM_MANUAL 378 379# 380# SPARSEMEM_EXTREME (which is the default) does some bootmem 381# allocations when sparse_init() is called. If this cannot 382# be done on your architecture, select this option. However, 383# statically allocating the mem_section[] array can potentially 384# consume vast quantities of .bss, so be careful. 385# 386# This option will also potentially produce smaller runtime code 387# with gcc 3.4 and later. 388# 389config SPARSEMEM_STATIC 390 bool 391 392# 393# Architecture platforms which require a two level mem_section in SPARSEMEM 394# must select this option. This is usually for architecture platforms with 395# an extremely sparse physical address space. 396# 397config SPARSEMEM_EXTREME 398 def_bool y 399 depends on SPARSEMEM && !SPARSEMEM_STATIC 400 401config SPARSEMEM_VMEMMAP_ENABLE 402 bool 403 404config SPARSEMEM_VMEMMAP 405 def_bool y 406 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE 407 help 408 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise 409 pfn_to_page and page_to_pfn operations. This is the most 410 efficient option when sufficient kernel resources are available. 411 412config SPARSEMEM_VMEMMAP_PREINIT 413 bool 414# 415# Select this config option from the architecture Kconfig, if it is preferred 416# to enable the feature of HugeTLB/dev_dax vmemmap optimization. 417# 418config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP 419 bool 420 421config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP 422 bool 423 424config ARCH_WANT_HUGETLB_VMEMMAP_PREINIT 425 bool 426 427config HAVE_MEMBLOCK_PHYS_MAP 428 bool 429 430config HAVE_GUP_FAST 431 depends on MMU 432 bool 433 434# Enable memblock support for scratch memory which is needed for kexec handover 435config MEMBLOCK_KHO_SCRATCH 436 bool 437 438# Don't discard allocated memory used to track "memory" and "reserved" memblocks 439# after early boot, so it can still be used to test for validity of memory. 440# Also, memblocks are updated with memory hot(un)plug. 441config ARCH_KEEP_MEMBLOCK 442 bool 443 444# Keep arch NUMA mapping infrastructure post-init. 445config NUMA_KEEP_MEMINFO 446 bool 447 448config MEMORY_ISOLATION 449 bool 450 451# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked 452# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via 453# /dev/mem. 454config EXCLUSIVE_SYSTEM_RAM 455 def_bool y 456 depends on !DEVMEM || STRICT_DEVMEM 457 458# 459# Only be set on architectures that have completely implemented memory hotplug 460# feature. If you are not sure, don't touch it. 461# 462config HAVE_BOOTMEM_INFO_NODE 463 def_bool n 464 465config ARCH_ENABLE_MEMORY_HOTPLUG 466 bool 467 468config ARCH_ENABLE_MEMORY_HOTREMOVE 469 bool 470 471# eventually, we can have this option just 'select SPARSEMEM' 472menuconfig MEMORY_HOTPLUG 473 bool "Memory hotplug" 474 select MEMORY_ISOLATION 475 depends on SPARSEMEM 476 depends on ARCH_ENABLE_MEMORY_HOTPLUG 477 depends on 64BIT 478 select NUMA_KEEP_MEMINFO if NUMA 479 480if MEMORY_HOTPLUG 481 482choice 483 prompt "Memory Hotplug Default Online Type" 484 default MHP_DEFAULT_ONLINE_TYPE_OFFLINE 485 help 486 Default memory type for hotplugged memory. 487 488 This option sets the default policy setting for memory hotplug 489 onlining policy (/sys/devices/system/memory/auto_online_blocks) which 490 determines what happens to newly added memory regions. Policy setting 491 can always be changed at runtime. 492 493 The default is 'offline'. 494 495 Select offline to defer onlining to drivers and user policy. 496 Select auto to let the kernel choose what zones to utilize. 497 Select online_kernel to generally allow kernel usage of this memory. 498 Select online_movable to generally disallow kernel usage of this memory. 499 500 Example kernel usage would be page structs and page tables. 501 502 See Documentation/admin-guide/mm/memory-hotplug.rst for more information. 503 504config MHP_DEFAULT_ONLINE_TYPE_OFFLINE 505 bool "offline" 506 help 507 Hotplugged memory will not be onlined by default. 508 Choose this for systems with drivers and user policy that 509 handle onlining of hotplug memory policy. 510 511config MHP_DEFAULT_ONLINE_TYPE_ONLINE_AUTO 512 bool "auto" 513 help 514 Select this if you want the kernel to automatically online 515 hotplugged memory into the zone it thinks is reasonable. 516 This memory may be utilized for kernel data. 517 518config MHP_DEFAULT_ONLINE_TYPE_ONLINE_KERNEL 519 bool "kernel" 520 help 521 Select this if you want the kernel to automatically online 522 hotplugged memory into a zone capable of being used for kernel 523 data. This typically means ZONE_NORMAL. 524 525config MHP_DEFAULT_ONLINE_TYPE_ONLINE_MOVABLE 526 bool "movable" 527 help 528 Select this if you want the kernel to automatically online 529 hotplug memory into ZONE_MOVABLE. This memory will generally 530 not be utilized for kernel data. 531 532 This should only be used when the admin knows sufficient 533 ZONE_NORMAL memory is available to describe hotplug memory, 534 otherwise hotplug memory may fail to online. For example, 535 sufficient kernel-capable memory (ZONE_NORMAL) must be 536 available to allocate page structs to describe ZONE_MOVABLE. 537 538endchoice 539 540config MEMORY_HOTREMOVE 541 bool "Allow for memory hot remove" 542 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64) 543 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE 544 depends on MIGRATION 545 546config MHP_MEMMAP_ON_MEMORY 547 def_bool y 548 depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP 549 depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 550 551endif # MEMORY_HOTPLUG 552 553config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE 554 bool 555 556# Heavily threaded applications may benefit from splitting the mm-wide 557# page_table_lock, so that faults on different parts of the user address 558# space can be handled with less contention: split it at this NR_CPUS. 559# Default to 4 for wider testing, though 8 might be more appropriate. 560# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock. 561# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes. 562# SPARC32 allocates multiple pte tables within a single page, and therefore 563# a per-page lock leads to problems when multiple tables need to be locked 564# at the same time (e.g. copy_page_range()). 565# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page. 566# 567config SPLIT_PTE_PTLOCKS 568 def_bool y 569 depends on MMU 570 depends on SMP 571 depends on NR_CPUS >= 4 572 depends on !ARM || CPU_CACHE_VIPT 573 depends on !PARISC || PA20 574 depends on !SPARC32 575 576config ARCH_ENABLE_SPLIT_PMD_PTLOCK 577 bool 578 579config SPLIT_PMD_PTLOCKS 580 def_bool y 581 depends on SPLIT_PTE_PTLOCKS && ARCH_ENABLE_SPLIT_PMD_PTLOCK 582 583# 584# support for memory balloon 585config MEMORY_BALLOON 586 bool 587 588# 589# support for memory balloon compaction 590config BALLOON_COMPACTION 591 bool "Allow for balloon memory compaction/migration" 592 default y 593 depends on COMPACTION && MEMORY_BALLOON 594 help 595 Memory fragmentation introduced by ballooning might reduce 596 significantly the number of 2MB contiguous memory blocks that can be 597 used within a guest, thus imposing performance penalties associated 598 with the reduced number of transparent huge pages that could be used 599 by the guest workload. Allowing the compaction & migration for memory 600 pages enlisted as being part of memory balloon devices avoids the 601 scenario aforementioned and helps improving memory defragmentation. 602 603# 604# support for memory compaction 605config COMPACTION 606 bool "Allow for memory compaction" 607 default y 608 select MIGRATION 609 depends on MMU 610 help 611 Compaction is the only memory management component to form 612 high order (larger physically contiguous) memory blocks 613 reliably. The page allocator relies on compaction heavily and 614 the lack of the feature can lead to unexpected OOM killer 615 invocations for high order memory requests. You shouldn't 616 disable this option unless there really is a strong reason for 617 it and then we would be really interested to hear about that at 618 linux-mm@kvack.org. 619 620config COMPACT_UNEVICTABLE_DEFAULT 621 int 622 depends on COMPACTION 623 default 0 if PREEMPT_RT 624 default 1 625 626# 627# support for free page reporting 628config PAGE_REPORTING 629 bool "Free page reporting" 630 help 631 Free page reporting allows for the incremental acquisition of 632 free pages from the buddy allocator for the purpose of reporting 633 those pages to another entity, such as a hypervisor, so that the 634 memory can be freed within the host for other uses. 635 636# 637# support for page migration 638# 639config MIGRATION 640 bool "Page migration" 641 default y 642 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU 643 help 644 Allows the migration of the physical location of pages of processes 645 while the virtual addresses are not changed. This is useful in 646 two situations. The first is on NUMA systems to put pages nearer 647 to the processors accessing. The second is when allocating huge 648 pages as migration can relocate pages to satisfy a huge page 649 allocation instead of reclaiming. 650 651config DEVICE_MIGRATION 652 def_bool MIGRATION && ZONE_DEVICE 653 654config ARCH_ENABLE_HUGEPAGE_MIGRATION 655 bool 656 657config ARCH_ENABLE_THP_MIGRATION 658 bool 659 660config HUGETLB_PAGE_SIZE_VARIABLE 661 def_bool n 662 help 663 Allows the pageblock_order value to be dynamic instead of just standard 664 HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available 665 on a platform. 666 667 Note that the pageblock_order cannot exceed MAX_PAGE_ORDER and will be 668 clamped down to MAX_PAGE_ORDER. 669 670config CONTIG_ALLOC 671 def_bool (MEMORY_ISOLATION && COMPACTION) || CMA 672 673config PCP_BATCH_SCALE_MAX 674 int "Maximum scale factor of PCP (Per-CPU pageset) batch allocate/free" 675 default 5 676 range 0 6 677 help 678 In page allocator, PCP (Per-CPU pageset) is refilled and drained in 679 batches. The batch number is scaled automatically to improve page 680 allocation/free throughput. But too large scale factor may hurt 681 latency. This option sets the upper limit of scale factor to limit 682 the maximum latency. 683 684config PHYS_ADDR_T_64BIT 685 def_bool 64BIT 686 687config MMU_NOTIFIER 688 bool 689 select INTERVAL_TREE 690 691config KSM 692 bool "Enable KSM for page merging" 693 depends on MMU 694 select XXHASH 695 help 696 Enable Kernel Samepage Merging: KSM periodically scans those areas 697 of an application's address space that an app has advised may be 698 mergeable. When it finds pages of identical content, it replaces 699 the many instances by a single page with that content, so 700 saving memory until one or another app needs to modify the content. 701 Recommended for use with KVM, or with other duplicative applications. 702 See Documentation/mm/ksm.rst for more information: KSM is inactive 703 until a program has madvised that an area is MADV_MERGEABLE, and 704 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set). 705 706config DEFAULT_MMAP_MIN_ADDR 707 int "Low address space to protect from user allocation" 708 depends on MMU 709 default 4096 710 help 711 This is the portion of low virtual memory which should be protected 712 from userspace allocation. Keeping a user from writing to low pages 713 can help reduce the impact of kernel NULL pointer bugs. 714 715 For most arm64, ppc64 and x86 users with lots of address space 716 a value of 65536 is reasonable and should cause no problems. 717 On arm and other archs it should not be higher than 32768. 718 Programs which use vm86 functionality or have some need to map 719 this low address space will need CAP_SYS_RAWIO or disable this 720 protection by setting the value to 0. 721 722 This value can be changed after boot using the 723 /proc/sys/vm/mmap_min_addr tunable. 724 725config ARCH_SUPPORTS_MEMORY_FAILURE 726 bool 727 728config MEMORY_FAILURE 729 depends on MMU 730 depends on ARCH_SUPPORTS_MEMORY_FAILURE 731 bool "Enable recovery from hardware memory errors" 732 select INTERVAL_TREE 733 help 734 Enables code to recover from some memory failures on systems 735 with MCA recovery. This allows a system to continue running 736 even when some of its memory has uncorrected errors. This requires 737 special hardware support and typically ECC memory. 738 739config HWPOISON_INJECT 740 tristate "HWPoison pages injector" 741 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS 742 select PROC_PAGE_MONITOR 743 744config NOMMU_INITIAL_TRIM_EXCESS 745 int "Turn on mmap() excess space trimming before booting" 746 depends on !MMU 747 default 1 748 help 749 The NOMMU mmap() frequently needs to allocate large contiguous chunks 750 of memory on which to store mappings, but it can only ask the system 751 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently 752 more than it requires. To deal with this, mmap() is able to trim off 753 the excess and return it to the allocator. 754 755 If trimming is enabled, the excess is trimmed off and returned to the 756 system allocator, which can cause extra fragmentation, particularly 757 if there are a lot of transient processes. 758 759 If trimming is disabled, the excess is kept, but not used, which for 760 long-term mappings means that the space is wasted. 761 762 Trimming can be dynamically controlled through a sysctl option 763 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of 764 excess pages there must be before trimming should occur, or zero if 765 no trimming is to occur. 766 767 This option specifies the initial value of this option. The default 768 of 1 says that all excess pages should be trimmed. 769 770 See Documentation/admin-guide/mm/nommu-mmap.rst for more information. 771 772config ARCH_WANT_GENERAL_HUGETLB 773 bool 774 775config ARCH_WANTS_THP_SWAP 776 def_bool n 777 778config PERSISTENT_HUGE_ZERO_FOLIO 779 bool "Allocate a PMD sized folio for zeroing" 780 depends on TRANSPARENT_HUGEPAGE 781 help 782 Enable this option to reduce the runtime refcounting overhead 783 of the huge zero folio and expand the places in the kernel 784 that can use huge zero folios. For instance, block I/O benefits 785 from access to large folios for zeroing memory. 786 787 With this option enabled, the huge zero folio is allocated 788 once and never freed. One full huge page's worth of memory shall 789 be used. 790 791 Say Y if your system has lots of memory. Say N if you are 792 memory constrained. 793 794config MM_ID 795 def_bool n 796 797menuconfig TRANSPARENT_HUGEPAGE 798 bool "Transparent Hugepage Support" 799 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT 800 select COMPACTION 801 select XARRAY_MULTI 802 select MM_ID 803 help 804 Transparent Hugepages allows the kernel to use huge pages and 805 huge tlb transparently to the applications whenever possible. 806 This feature can improve computing performance to certain 807 applications by speeding up page faults during memory 808 allocation, by reducing the number of tlb misses and by speeding 809 up the pagetable walking. 810 811 If memory constrained on embedded, you may want to say N. 812 813if TRANSPARENT_HUGEPAGE 814 815choice 816 prompt "Transparent Hugepage Support sysfs defaults" 817 depends on TRANSPARENT_HUGEPAGE 818 default TRANSPARENT_HUGEPAGE_ALWAYS 819 help 820 Selects the sysfs defaults for Transparent Hugepage Support. 821 822 config TRANSPARENT_HUGEPAGE_ALWAYS 823 bool "always" 824 help 825 Enabling Transparent Hugepage always, can increase the 826 memory footprint of applications without a guaranteed 827 benefit but it will work automatically for all applications. 828 829 config TRANSPARENT_HUGEPAGE_MADVISE 830 bool "madvise" 831 help 832 Enabling Transparent Hugepage madvise, will only provide a 833 performance improvement benefit to the applications using 834 madvise(MADV_HUGEPAGE) but it won't risk to increase the 835 memory footprint of applications without a guaranteed 836 benefit. 837 838 config TRANSPARENT_HUGEPAGE_NEVER 839 bool "never" 840 help 841 Disable Transparent Hugepage by default. It can still be 842 enabled at runtime via sysfs. 843endchoice 844 845choice 846 prompt "Shmem hugepage allocation defaults" 847 depends on TRANSPARENT_HUGEPAGE 848 default TRANSPARENT_HUGEPAGE_SHMEM_HUGE_NEVER 849 help 850 Selects the hugepage allocation policy defaults for 851 the internal shmem mount. 852 853 The selection made here can be overridden by using the kernel 854 command line 'transparent_hugepage_shmem=' option. 855 856 config TRANSPARENT_HUGEPAGE_SHMEM_HUGE_NEVER 857 bool "never" 858 help 859 Disable hugepage allocation for shmem mount by default. It can 860 still be enabled with the kernel command line 861 'transparent_hugepage_shmem=' option or at runtime via sysfs 862 knob. Note that madvise(MADV_COLLAPSE) can still cause 863 transparent huge pages to be obtained even if this mode is 864 specified. 865 866 config TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ALWAYS 867 bool "always" 868 help 869 Always attempt to allocate hugepage for shmem mount, can 870 increase the memory footprint of applications without a 871 guaranteed benefit but it will work automatically for all 872 applications. 873 874 config TRANSPARENT_HUGEPAGE_SHMEM_HUGE_WITHIN_SIZE 875 bool "within_size" 876 help 877 Enable hugepage allocation for shmem mount if the allocation 878 will be fully within the i_size. This configuration also takes 879 into account any madvise(MADV_HUGEPAGE) hints that may be 880 provided by the applications. 881 882 config TRANSPARENT_HUGEPAGE_SHMEM_HUGE_ADVISE 883 bool "advise" 884 help 885 Enable hugepage allocation for the shmem mount exclusively when 886 applications supply the madvise(MADV_HUGEPAGE) hint. 887 This ensures that hugepages are used only in response to explicit 888 requests from applications. 889endchoice 890 891choice 892 prompt "Tmpfs hugepage allocation defaults" 893 depends on TRANSPARENT_HUGEPAGE 894 default TRANSPARENT_HUGEPAGE_TMPFS_HUGE_NEVER 895 help 896 Selects the hugepage allocation policy defaults for 897 the tmpfs mount. 898 899 The selection made here can be overridden by using the kernel 900 command line 'transparent_hugepage_tmpfs=' option. 901 902 config TRANSPARENT_HUGEPAGE_TMPFS_HUGE_NEVER 903 bool "never" 904 help 905 Disable hugepage allocation for tmpfs mount by default. It can 906 still be enabled with the kernel command line 907 'transparent_hugepage_tmpfs=' option. Note that 908 madvise(MADV_COLLAPSE) can still cause transparent huge pages 909 to be obtained even if this mode is specified. 910 911 config TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ALWAYS 912 bool "always" 913 help 914 Always attempt to allocate hugepage for tmpfs mount, can 915 increase the memory footprint of applications without a 916 guaranteed benefit but it will work automatically for all 917 applications. 918 919 config TRANSPARENT_HUGEPAGE_TMPFS_HUGE_WITHIN_SIZE 920 bool "within_size" 921 help 922 Enable hugepage allocation for tmpfs mount if the allocation 923 will be fully within the i_size. This configuration also takes 924 into account any madvise(MADV_HUGEPAGE) hints that may be 925 provided by the applications. 926 927 config TRANSPARENT_HUGEPAGE_TMPFS_HUGE_ADVISE 928 bool "advise" 929 help 930 Enable hugepage allocation for the tmpfs mount exclusively when 931 applications supply the madvise(MADV_HUGEPAGE) hint. 932 This ensures that hugepages are used only in response to explicit 933 requests from applications. 934endchoice 935 936config THP_SWAP 937 def_bool y 938 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT 939 help 940 Swap transparent huge pages in one piece, without splitting. 941 XXX: For now, swap cluster backing transparent huge page 942 will be split after swapout. 943 944 For selection by architectures with reasonable THP sizes. 945 946config READ_ONLY_THP_FOR_FS 947 bool "Read-only THP for filesystems (EXPERIMENTAL)" 948 depends on TRANSPARENT_HUGEPAGE 949 950 help 951 Allow khugepaged to put read-only file-backed pages in THP. 952 953 This is marked experimental because it is a new feature. Write 954 support of file THPs will be developed in the next few release 955 cycles. 956 957config NO_PAGE_MAPCOUNT 958 bool "No per-page mapcount (EXPERIMENTAL)" 959 help 960 Do not maintain per-page mapcounts for pages part of larger 961 allocations, such as transparent huge pages. 962 963 When this config option is enabled, some interfaces that relied on 964 this information will rely on less-precise per-allocation information 965 instead: for example, using the average per-page mapcount in such 966 a large allocation instead of the per-page mapcount. 967 968 EXPERIMENTAL because the impact of some changes is still unclear. 969 970endif # TRANSPARENT_HUGEPAGE 971 972# simple helper to make the code a bit easier to read 973config PAGE_MAPCOUNT 974 def_bool !NO_PAGE_MAPCOUNT 975 976# 977# The architecture supports pgtable leaves that is larger than PAGE_SIZE 978# 979config PGTABLE_HAS_HUGE_LEAVES 980 def_bool TRANSPARENT_HUGEPAGE || HUGETLB_PAGE 981 982# 983# We can end up creating gigantic folio. 984# 985config HAVE_GIGANTIC_FOLIOS 986 def_bool (HUGETLB_PAGE && ARCH_HAS_GIGANTIC_PAGE) || \ 987 (ZONE_DEVICE && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) 988 989config ASYNC_KERNEL_PGTABLE_FREE 990 def_bool n 991 992# TODO: Allow to be enabled without THP 993config ARCH_SUPPORTS_HUGE_PFNMAP 994 def_bool n 995 depends on TRANSPARENT_HUGEPAGE 996 997config ARCH_SUPPORTS_PMD_PFNMAP 998 def_bool y 999 depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE 1000 1001config ARCH_SUPPORTS_PUD_PFNMAP 1002 def_bool y 1003 depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1004 1005# 1006# Architectures that always use weak definitions for percpu 1007# variables in modules should set this. 1008# 1009config ARCH_MODULE_NEEDS_WEAK_PER_CPU 1010 bool 1011 1012# 1013# UP and nommu archs use km based percpu allocator 1014# 1015config NEED_PER_CPU_KM 1016 depends on !SMP || !MMU 1017 bool 1018 default y 1019 1020config NEED_PER_CPU_EMBED_FIRST_CHUNK 1021 bool 1022 1023config NEED_PER_CPU_PAGE_FIRST_CHUNK 1024 bool 1025 1026config USE_PERCPU_NUMA_NODE_ID 1027 bool 1028 1029config HAVE_SETUP_PER_CPU_AREA 1030 bool 1031 1032config CMA 1033 bool "Contiguous Memory Allocator" 1034 depends on MMU 1035 select MIGRATION 1036 select MEMORY_ISOLATION 1037 help 1038 This enables the Contiguous Memory Allocator which allows other 1039 subsystems to allocate big physically-contiguous blocks of memory. 1040 CMA reserves a region of memory and allows only movable pages to 1041 be allocated from it. This way, the kernel can use the memory for 1042 pagecache and when a subsystem requests for contiguous area, the 1043 allocated pages are migrated away to serve the contiguous request. 1044 1045 If unsure, say "n". 1046 1047config CMA_DEBUGFS 1048 bool "CMA debugfs interface" 1049 depends on CMA && DEBUG_FS 1050 help 1051 Turns on the DebugFS interface for CMA. 1052 1053config CMA_SYSFS 1054 bool "CMA information through sysfs interface" 1055 depends on CMA && SYSFS 1056 help 1057 This option exposes some sysfs attributes to get information 1058 from CMA. 1059 1060config CMA_AREAS 1061 int "Maximum count of the CMA areas" 1062 depends on CMA 1063 default 20 if NUMA 1064 default 8 1065 help 1066 CMA allows to create CMA areas for particular purpose, mainly, 1067 used as device private area. This parameter sets the maximum 1068 number of CMA area in the system. 1069 1070 If unsure, leave the default value "8" in UMA and "20" in NUMA. 1071 1072# 1073# Select this config option from the architecture Kconfig, if available, to set 1074# the max page order for physically contiguous allocations. 1075# 1076config ARCH_FORCE_MAX_ORDER 1077 int 1078 1079# 1080# When ARCH_FORCE_MAX_ORDER is not defined, 1081# the default page block order is MAX_PAGE_ORDER (10) as per 1082# include/linux/mmzone.h. 1083# 1084config PAGE_BLOCK_MAX_ORDER 1085 int "Page Block Order Upper Limit" 1086 range 1 10 if ARCH_FORCE_MAX_ORDER = 0 1087 default 10 if ARCH_FORCE_MAX_ORDER = 0 1088 range 1 ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER != 0 1089 default ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER != 0 1090 help 1091 The page block order refers to the power of two number of pages that 1092 are physically contiguous and can have a migrate type associated to 1093 them. The maximum size of the page block order is at least limited by 1094 ARCH_FORCE_MAX_ORDER/MAX_PAGE_ORDER. 1095 1096 This config adds a new upper limit of default page block 1097 order when the page block order is required to be smaller than 1098 ARCH_FORCE_MAX_ORDER/MAX_PAGE_ORDER or other limits 1099 (see include/linux/pageblock-flags.h for details). 1100 1101 Reducing pageblock order can negatively impact THP generation 1102 success rate. If your workloads use THP heavily, please use this 1103 option with caution. 1104 1105 Don't change if unsure. 1106 1107config MEM_SOFT_DIRTY 1108 bool "Track memory changes" 1109 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS 1110 select PROC_PAGE_MONITOR 1111 help 1112 This option enables memory changes tracking by introducing a 1113 soft-dirty bit on pte-s. This bit it set when someone writes 1114 into a page just as regular dirty bit, but unlike the latter 1115 it can be cleared by hands. 1116 1117 See Documentation/admin-guide/mm/soft-dirty.rst for more details. 1118 1119config GENERIC_EARLY_IOREMAP 1120 bool 1121 1122config STACK_MAX_DEFAULT_SIZE_MB 1123 int "Default maximum user stack size for 32-bit processes (MB)" 1124 default 100 1125 range 8 2048 1126 depends on STACK_GROWSUP && (!64BIT || COMPAT) 1127 help 1128 This is the maximum stack size in Megabytes in the VM layout of 32-bit 1129 user processes when the stack grows upwards (currently only on parisc 1130 arch) when the RLIMIT_STACK hard limit is unlimited. 1131 1132 A sane initial value is 100 MB. 1133 1134config DEFERRED_STRUCT_PAGE_INIT 1135 bool "Defer initialisation of struct pages to kthreads" 1136 depends on SPARSEMEM 1137 depends on !NEED_PER_CPU_KM 1138 depends on 64BIT 1139 depends on !KMSAN 1140 select PADATA 1141 help 1142 Ordinarily all struct pages are initialised during early boot in a 1143 single thread. On very large machines this can take a considerable 1144 amount of time. If this option is set, large machines will bring up 1145 a subset of memmap at boot and then initialise the rest in parallel. 1146 This has a potential performance impact on tasks running early in the 1147 lifetime of the system until these kthreads finish the 1148 initialisation. 1149 1150config PAGE_IDLE_FLAG 1151 bool 1152 select PAGE_EXTENSION if !64BIT 1153 help 1154 This adds PG_idle and PG_young flags to 'struct page'. PTE Accessed 1155 bit writers can set the state of the bit in the flags so that PTE 1156 Accessed bit readers may avoid disturbance. 1157 1158config IDLE_PAGE_TRACKING 1159 bool "Enable idle page tracking" 1160 depends on SYSFS && MMU 1161 select PAGE_IDLE_FLAG 1162 help 1163 This feature allows to estimate the amount of user pages that have 1164 not been touched during a given period of time. This information can 1165 be useful to tune memory cgroup limits and/or for job placement 1166 within a compute cluster. 1167 1168 See Documentation/admin-guide/mm/idle_page_tracking.rst for 1169 more details. 1170 1171# Architectures which implement cpu_dcache_is_aliasing() to query 1172# whether the data caches are aliased (VIVT or VIPT with dcache 1173# aliasing) need to select this. 1174config ARCH_HAS_CPU_CACHE_ALIASING 1175 bool 1176 1177config ARCH_HAS_CACHE_LINE_SIZE 1178 bool 1179 1180config ARCH_HAS_CURRENT_STACK_POINTER 1181 bool 1182 help 1183 In support of HARDENED_USERCOPY performing stack variable lifetime 1184 checking, an architecture-agnostic way to find the stack pointer 1185 is needed. Once an architecture defines an unsigned long global 1186 register alias named "current_stack_pointer", this config can be 1187 selected. 1188 1189config ARCH_HAS_ZONE_DMA_SET 1190 bool 1191 1192config ZONE_DMA 1193 bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET 1194 default y if ARM64 || X86 1195 1196config ZONE_DMA32 1197 bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET 1198 depends on !X86_32 1199 default y if ARM64 1200 1201config ZONE_DEVICE 1202 bool "Device memory (pmem, HMM, etc...) hotplug support" 1203 depends on MEMORY_HOTPLUG 1204 depends on MEMORY_HOTREMOVE 1205 depends on SPARSEMEM_VMEMMAP 1206 select XARRAY_MULTI 1207 1208 help 1209 Device memory hotplug support allows for establishing pmem, 1210 or other device driver discovered memory regions, in the 1211 memmap. This allows pfn_to_page() lookups of otherwise 1212 "device-physical" addresses which is needed for using a DAX 1213 mapping in an O_DIRECT operation, among other things. 1214 1215 If FS_DAX is enabled, then say Y. 1216 1217# 1218# Helpers to mirror range of the CPU page tables of a process into device page 1219# tables. 1220# 1221config HMM_MIRROR 1222 bool 1223 depends on MMU 1224 1225config GET_FREE_REGION 1226 bool 1227 1228config DEVICE_PRIVATE 1229 bool "Unaddressable device memory (GPU memory, ...)" 1230 depends on ZONE_DEVICE 1231 select GET_FREE_REGION 1232 1233 help 1234 Allows creation of struct pages to represent unaddressable device 1235 memory; i.e., memory that is only accessible from the device (or 1236 group of devices). You likely also want to select HMM_MIRROR. 1237 1238config VMAP_PFN 1239 bool 1240 1241config ARCH_USES_HIGH_VMA_FLAGS 1242 bool 1243config ARCH_HAS_PKEYS 1244 bool 1245 1246config ARCH_USES_PG_ARCH_2 1247 bool 1248config ARCH_USES_PG_ARCH_3 1249 bool 1250 1251config VM_EVENT_COUNTERS 1252 default y 1253 bool "Enable VM event counters for /proc/vmstat" if EXPERT 1254 help 1255 VM event counters are needed for event counts to be shown. 1256 This option allows the disabling of the VM event counters 1257 on EXPERT systems. /proc/vmstat will only show page counts 1258 if VM event counters are disabled. 1259 1260config PERCPU_STATS 1261 bool "Collect percpu memory statistics" 1262 help 1263 This feature collects and exposes statistics via debugfs. The 1264 information includes global and per chunk statistics, which can 1265 be used to help understand percpu memory usage. 1266 1267config GUP_TEST 1268 bool "Enable infrastructure for get_user_pages()-related unit tests" 1269 depends on DEBUG_FS 1270 help 1271 Provides /sys/kernel/debug/gup_test, which in turn provides a way 1272 to make ioctl calls that can launch kernel-based unit tests for 1273 the get_user_pages*() and pin_user_pages*() family of API calls. 1274 1275 These tests include benchmark testing of the _fast variants of 1276 get_user_pages*() and pin_user_pages*(), as well as smoke tests of 1277 the non-_fast variants. 1278 1279 There is also a sub-test that allows running dump_page() on any 1280 of up to eight pages (selected by command line args) within the 1281 range of user-space addresses. These pages are either pinned via 1282 pin_user_pages*(), or pinned via get_user_pages*(), as specified 1283 by other command line arguments. 1284 1285 See tools/testing/selftests/mm/gup_test.c 1286 1287comment "GUP_TEST needs to have DEBUG_FS enabled" 1288 depends on !GUP_TEST && !DEBUG_FS 1289 1290config GUP_GET_PXX_LOW_HIGH 1291 bool 1292 1293config DMAPOOL_TEST 1294 tristate "Enable a module to run time tests on dma_pool" 1295 depends on HAS_DMA 1296 help 1297 Provides a test module that will allocate and free many blocks of 1298 various sizes and report how long it takes. This is intended to 1299 provide a consistent way to measure how changes to the 1300 dma_pool_alloc/free routines affect performance. 1301 1302config ARCH_HAS_PTE_SPECIAL 1303 bool 1304 1305config MAPPING_DIRTY_HELPERS 1306 bool 1307 1308config KMAP_LOCAL 1309 bool 1310 1311config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY 1312 bool 1313 1314config MEMFD_CREATE 1315 bool "Enable memfd_create() system call" if EXPERT 1316 1317config SECRETMEM 1318 default y 1319 bool "Enable memfd_secret() system call" if EXPERT 1320 depends on ARCH_HAS_SET_DIRECT_MAP 1321 help 1322 Enable the memfd_secret() system call with the ability to create 1323 memory areas visible only in the context of the owning process and 1324 not mapped to other processes and other kernel page tables. 1325 1326config ANON_VMA_NAME 1327 bool "Anonymous VMA name support" 1328 depends on PROC_FS && ADVISE_SYSCALLS && MMU 1329 1330 help 1331 Allow naming anonymous virtual memory areas. 1332 1333 This feature allows assigning names to virtual memory areas. Assigned 1334 names can be later retrieved from /proc/pid/maps and /proc/pid/smaps 1335 and help identifying individual anonymous memory areas. 1336 Assigning a name to anonymous virtual memory area might prevent that 1337 area from being merged with adjacent virtual memory areas due to the 1338 difference in their name. 1339 1340config HAVE_ARCH_USERFAULTFD_WP 1341 bool 1342 help 1343 Arch has userfaultfd write protection support 1344 1345config HAVE_ARCH_USERFAULTFD_MINOR 1346 bool 1347 help 1348 Arch has userfaultfd minor fault support 1349 1350menuconfig USERFAULTFD 1351 bool "Enable userfaultfd() system call" 1352 depends on MMU 1353 help 1354 Enable the userfaultfd() system call that allows to intercept and 1355 handle page faults in userland. 1356 1357if USERFAULTFD 1358config PTE_MARKER_UFFD_WP 1359 bool "Userfaultfd write protection support for shmem/hugetlbfs" 1360 default y 1361 depends on HAVE_ARCH_USERFAULTFD_WP 1362 1363 help 1364 Allows to create marker PTEs for userfaultfd write protection 1365 purposes. It is required to enable userfaultfd write protection on 1366 file-backed memory types like shmem and hugetlbfs. 1367endif # USERFAULTFD 1368 1369# multi-gen LRU { 1370config LRU_GEN 1371 bool "Multi-Gen LRU" 1372 depends on MMU 1373 # make sure folio->flags has enough spare bits 1374 depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP 1375 help 1376 A high performance LRU implementation to overcommit memory. See 1377 Documentation/admin-guide/mm/multigen_lru.rst for details. 1378 1379config LRU_GEN_ENABLED 1380 bool "Enable by default" 1381 depends on LRU_GEN 1382 help 1383 This option enables the multi-gen LRU by default. 1384 1385config LRU_GEN_STATS 1386 bool "Full stats for debugging" 1387 depends on LRU_GEN 1388 help 1389 Do not enable this option unless you plan to look at historical stats 1390 from evicted generations for debugging purpose. 1391 1392 This option has a per-memcg and per-node memory overhead. 1393 1394config LRU_GEN_WALKS_MMU 1395 def_bool y 1396 depends on LRU_GEN && ARCH_HAS_HW_PTE_YOUNG 1397# } 1398 1399config ARCH_SUPPORTS_PER_VMA_LOCK 1400 def_bool n 1401 1402config PER_VMA_LOCK 1403 def_bool y 1404 depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP 1405 help 1406 Allow per-vma locking during page fault handling. 1407 1408 This feature allows locking each virtual memory area separately when 1409 handling page faults instead of taking mmap_lock. 1410 1411config LOCK_MM_AND_FIND_VMA 1412 bool 1413 depends on !STACK_GROWSUP 1414 1415config IOMMU_MM_DATA 1416 bool 1417 1418config EXECMEM 1419 bool 1420 1421config NUMA_MEMBLKS 1422 bool 1423 1424config NUMA_EMU 1425 bool "NUMA emulation" 1426 depends on NUMA_MEMBLKS 1427 depends on X86 || GENERIC_ARCH_NUMA 1428 help 1429 Enable NUMA emulation. A flat machine will be split 1430 into virtual nodes when booted with "numa=fake=N", where N is the 1431 number of nodes. This is only useful for debugging. 1432 1433config ARCH_HAS_USER_SHADOW_STACK 1434 bool 1435 help 1436 The architecture has hardware support for userspace shadow call 1437 stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss). 1438 1439config ARCH_SUPPORTS_PT_RECLAIM 1440 def_bool n 1441 1442config PT_RECLAIM 1443 bool "reclaim empty user page table pages" 1444 default y 1445 depends on ARCH_SUPPORTS_PT_RECLAIM && MMU && SMP 1446 select MMU_GATHER_RCU_TABLE_FREE 1447 help 1448 Try to reclaim empty user page table pages in paths other than munmap 1449 and exit_mmap path. 1450 1451 Note: now only empty user PTE page table pages will be reclaimed. 1452 1453config FIND_NORMAL_PAGE 1454 def_bool n 1455 1456source "mm/damon/Kconfig" 1457 1458endmenu 1459