Loading...
1# SPDX-License-Identifier: GPL-2.0-only
2
3menu "Memory Management options"
4
5config SELECT_MEMORY_MODEL
6 def_bool y
7 depends on ARCH_SELECT_MEMORY_MODEL
8
9choice
10 prompt "Memory model"
11 depends on SELECT_MEMORY_MODEL
12 default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
13 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
14 default FLATMEM_MANUAL
15 help
16 This option allows you to change some of the ways that
17 Linux manages its memory internally. Most users will
18 only have one option here selected by the architecture
19 configuration. This is normal.
20
21config FLATMEM_MANUAL
22 bool "Flat Memory"
23 depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
24 help
25 This option is best suited for non-NUMA systems with
26 flat address space. The FLATMEM is the most efficient
27 system in terms of performance and resource consumption
28 and it is the best option for smaller systems.
29
30 For systems that have holes in their physical address
31 spaces and for features like NUMA and memory hotplug,
32 choose "Sparse Memory".
33
34 If unsure, choose this option (Flat Memory) over any other.
35
36config DISCONTIGMEM_MANUAL
37 bool "Discontiguous Memory"
38 depends on ARCH_DISCONTIGMEM_ENABLE
39 help
40 This option provides enhanced support for discontiguous
41 memory systems, over FLATMEM. These systems have holes
42 in their physical address spaces, and this option provides
43 more efficient handling of these holes.
44
45 Although "Discontiguous Memory" is still used by several
46 architectures, it is considered deprecated in favor of
47 "Sparse Memory".
48
49 If unsure, choose "Sparse Memory" over this option.
50
51config SPARSEMEM_MANUAL
52 bool "Sparse Memory"
53 depends on ARCH_SPARSEMEM_ENABLE
54 help
55 This will be the only option for some systems, including
56 memory hot-plug systems. This is normal.
57
58 This option provides efficient support for systems with
59 holes is their physical address space and allows memory
60 hot-plug and hot-remove.
61
62 If unsure, choose "Flat Memory" over this option.
63
64endchoice
65
66config DISCONTIGMEM
67 def_bool y
68 depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
69
70config SPARSEMEM
71 def_bool y
72 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
73
74config FLATMEM
75 def_bool y
76 depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
77
78config FLAT_NODE_MEM_MAP
79 def_bool y
80 depends on !SPARSEMEM
81
82#
83# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
84# to represent different areas of memory. This variable allows
85# those dependencies to exist individually.
86#
87config NEED_MULTIPLE_NODES
88 def_bool y
89 depends on DISCONTIGMEM || NUMA
90
91#
92# SPARSEMEM_EXTREME (which is the default) does some bootmem
93# allocations when sparse_init() is called. If this cannot
94# be done on your architecture, select this option. However,
95# statically allocating the mem_section[] array can potentially
96# consume vast quantities of .bss, so be careful.
97#
98# This option will also potentially produce smaller runtime code
99# with gcc 3.4 and later.
100#
101config SPARSEMEM_STATIC
102 bool
103
104#
105# Architecture platforms which require a two level mem_section in SPARSEMEM
106# must select this option. This is usually for architecture platforms with
107# an extremely sparse physical address space.
108#
109config SPARSEMEM_EXTREME
110 def_bool y
111 depends on SPARSEMEM && !SPARSEMEM_STATIC
112
113config SPARSEMEM_VMEMMAP_ENABLE
114 bool
115
116config SPARSEMEM_VMEMMAP
117 bool "Sparse Memory virtual memmap"
118 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
119 default y
120 help
121 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
122 pfn_to_page and page_to_pfn operations. This is the most
123 efficient option when sufficient kernel resources are available.
124
125config HAVE_MEMBLOCK_PHYS_MAP
126 bool
127
128config HAVE_FAST_GUP
129 depends on MMU
130 bool
131
132# Don't discard allocated memory used to track "memory" and "reserved" memblocks
133# after early boot, so it can still be used to test for validity of memory.
134# Also, memblocks are updated with memory hot(un)plug.
135config ARCH_KEEP_MEMBLOCK
136 bool
137
138# Keep arch NUMA mapping infrastructure post-init.
139config NUMA_KEEP_MEMINFO
140 bool
141
142config MEMORY_ISOLATION
143 bool
144
145#
146# Only be set on architectures that have completely implemented memory hotplug
147# feature. If you are not sure, don't touch it.
148#
149config HAVE_BOOTMEM_INFO_NODE
150 def_bool n
151
152# eventually, we can have this option just 'select SPARSEMEM'
153config MEMORY_HOTPLUG
154 bool "Allow for memory hot-add"
155 depends on SPARSEMEM || X86_64_ACPI_NUMA
156 depends on ARCH_ENABLE_MEMORY_HOTPLUG
157 depends on 64BIT || BROKEN
158 select NUMA_KEEP_MEMINFO if NUMA
159
160config MEMORY_HOTPLUG_SPARSE
161 def_bool y
162 depends on SPARSEMEM && MEMORY_HOTPLUG
163
164config MEMORY_HOTPLUG_DEFAULT_ONLINE
165 bool "Online the newly added memory blocks by default"
166 depends on MEMORY_HOTPLUG
167 help
168 This option sets the default policy setting for memory hotplug
169 onlining policy (/sys/devices/system/memory/auto_online_blocks) which
170 determines what happens to newly added memory regions. Policy setting
171 can always be changed at runtime.
172 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
173
174 Say Y here if you want all hot-plugged memory blocks to appear in
175 'online' state by default.
176 Say N here if you want the default policy to keep all hot-plugged
177 memory blocks in 'offline' state.
178
179config MEMORY_HOTREMOVE
180 bool "Allow for memory hot remove"
181 select MEMORY_ISOLATION
182 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
183 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
184 depends on MIGRATION
185
186# Heavily threaded applications may benefit from splitting the mm-wide
187# page_table_lock, so that faults on different parts of the user address
188# space can be handled with less contention: split it at this NR_CPUS.
189# Default to 4 for wider testing, though 8 might be more appropriate.
190# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
191# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
192# SPARC32 allocates multiple pte tables within a single page, and therefore
193# a per-page lock leads to problems when multiple tables need to be locked
194# at the same time (e.g. copy_page_range()).
195# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
196#
197config SPLIT_PTLOCK_CPUS
198 int
199 default "999999" if !MMU
200 default "999999" if ARM && !CPU_CACHE_VIPT
201 default "999999" if PARISC && !PA20
202 default "999999" if SPARC32
203 default "4"
204
205config ARCH_ENABLE_SPLIT_PMD_PTLOCK
206 bool
207
208#
209# support for memory balloon
210config MEMORY_BALLOON
211 bool
212
213#
214# support for memory balloon compaction
215config BALLOON_COMPACTION
216 bool "Allow for balloon memory compaction/migration"
217 def_bool y
218 depends on COMPACTION && MEMORY_BALLOON
219 help
220 Memory fragmentation introduced by ballooning might reduce
221 significantly the number of 2MB contiguous memory blocks that can be
222 used within a guest, thus imposing performance penalties associated
223 with the reduced number of transparent huge pages that could be used
224 by the guest workload. Allowing the compaction & migration for memory
225 pages enlisted as being part of memory balloon devices avoids the
226 scenario aforementioned and helps improving memory defragmentation.
227
228#
229# support for memory compaction
230config COMPACTION
231 bool "Allow for memory compaction"
232 def_bool y
233 select MIGRATION
234 depends on MMU
235 help
236 Compaction is the only memory management component to form
237 high order (larger physically contiguous) memory blocks
238 reliably. The page allocator relies on compaction heavily and
239 the lack of the feature can lead to unexpected OOM killer
240 invocations for high order memory requests. You shouldn't
241 disable this option unless there really is a strong reason for
242 it and then we would be really interested to hear about that at
243 linux-mm@kvack.org.
244
245#
246# support for free page reporting
247config PAGE_REPORTING
248 bool "Free page reporting"
249 def_bool n
250 help
251 Free page reporting allows for the incremental acquisition of
252 free pages from the buddy allocator for the purpose of reporting
253 those pages to another entity, such as a hypervisor, so that the
254 memory can be freed within the host for other uses.
255
256#
257# support for page migration
258#
259config MIGRATION
260 bool "Page migration"
261 def_bool y
262 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
263 help
264 Allows the migration of the physical location of pages of processes
265 while the virtual addresses are not changed. This is useful in
266 two situations. The first is on NUMA systems to put pages nearer
267 to the processors accessing. The second is when allocating huge
268 pages as migration can relocate pages to satisfy a huge page
269 allocation instead of reclaiming.
270
271config ARCH_ENABLE_HUGEPAGE_MIGRATION
272 bool
273
274config ARCH_ENABLE_THP_MIGRATION
275 bool
276
277config CONTIG_ALLOC
278 def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
279
280config PHYS_ADDR_T_64BIT
281 def_bool 64BIT
282
283config BOUNCE
284 bool "Enable bounce buffers"
285 default y
286 depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
287 help
288 Enable bounce buffers for devices that cannot access
289 the full range of memory available to the CPU. Enabled
290 by default when ZONE_DMA or HIGHMEM is selected, but you
291 may say n to override this.
292
293config VIRT_TO_BUS
294 bool
295 help
296 An architecture should select this if it implements the
297 deprecated interface virt_to_bus(). All new architectures
298 should probably not select this.
299
300
301config MMU_NOTIFIER
302 bool
303 select SRCU
304 select INTERVAL_TREE
305
306config KSM
307 bool "Enable KSM for page merging"
308 depends on MMU
309 select XXHASH
310 help
311 Enable Kernel Samepage Merging: KSM periodically scans those areas
312 of an application's address space that an app has advised may be
313 mergeable. When it finds pages of identical content, it replaces
314 the many instances by a single page with that content, so
315 saving memory until one or another app needs to modify the content.
316 Recommended for use with KVM, or with other duplicative applications.
317 See Documentation/vm/ksm.rst for more information: KSM is inactive
318 until a program has madvised that an area is MADV_MERGEABLE, and
319 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
320
321config DEFAULT_MMAP_MIN_ADDR
322 int "Low address space to protect from user allocation"
323 depends on MMU
324 default 4096
325 help
326 This is the portion of low virtual memory which should be protected
327 from userspace allocation. Keeping a user from writing to low pages
328 can help reduce the impact of kernel NULL pointer bugs.
329
330 For most ia64, ppc64 and x86 users with lots of address space
331 a value of 65536 is reasonable and should cause no problems.
332 On arm and other archs it should not be higher than 32768.
333 Programs which use vm86 functionality or have some need to map
334 this low address space will need CAP_SYS_RAWIO or disable this
335 protection by setting the value to 0.
336
337 This value can be changed after boot using the
338 /proc/sys/vm/mmap_min_addr tunable.
339
340config ARCH_SUPPORTS_MEMORY_FAILURE
341 bool
342
343config MEMORY_FAILURE
344 depends on MMU
345 depends on ARCH_SUPPORTS_MEMORY_FAILURE
346 bool "Enable recovery from hardware memory errors"
347 select MEMORY_ISOLATION
348 select RAS
349 help
350 Enables code to recover from some memory failures on systems
351 with MCA recovery. This allows a system to continue running
352 even when some of its memory has uncorrected errors. This requires
353 special hardware support and typically ECC memory.
354
355config HWPOISON_INJECT
356 tristate "HWPoison pages injector"
357 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
358 select PROC_PAGE_MONITOR
359
360config NOMMU_INITIAL_TRIM_EXCESS
361 int "Turn on mmap() excess space trimming before booting"
362 depends on !MMU
363 default 1
364 help
365 The NOMMU mmap() frequently needs to allocate large contiguous chunks
366 of memory on which to store mappings, but it can only ask the system
367 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
368 more than it requires. To deal with this, mmap() is able to trim off
369 the excess and return it to the allocator.
370
371 If trimming is enabled, the excess is trimmed off and returned to the
372 system allocator, which can cause extra fragmentation, particularly
373 if there are a lot of transient processes.
374
375 If trimming is disabled, the excess is kept, but not used, which for
376 long-term mappings means that the space is wasted.
377
378 Trimming can be dynamically controlled through a sysctl option
379 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
380 excess pages there must be before trimming should occur, or zero if
381 no trimming is to occur.
382
383 This option specifies the initial value of this option. The default
384 of 1 says that all excess pages should be trimmed.
385
386 See Documentation/mm/nommu-mmap.rst for more information.
387
388config TRANSPARENT_HUGEPAGE
389 bool "Transparent Hugepage Support"
390 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
391 select COMPACTION
392 select XARRAY_MULTI
393 help
394 Transparent Hugepages allows the kernel to use huge pages and
395 huge tlb transparently to the applications whenever possible.
396 This feature can improve computing performance to certain
397 applications by speeding up page faults during memory
398 allocation, by reducing the number of tlb misses and by speeding
399 up the pagetable walking.
400
401 If memory constrained on embedded, you may want to say N.
402
403choice
404 prompt "Transparent Hugepage Support sysfs defaults"
405 depends on TRANSPARENT_HUGEPAGE
406 default TRANSPARENT_HUGEPAGE_ALWAYS
407 help
408 Selects the sysfs defaults for Transparent Hugepage Support.
409
410 config TRANSPARENT_HUGEPAGE_ALWAYS
411 bool "always"
412 help
413 Enabling Transparent Hugepage always, can increase the
414 memory footprint of applications without a guaranteed
415 benefit but it will work automatically for all applications.
416
417 config TRANSPARENT_HUGEPAGE_MADVISE
418 bool "madvise"
419 help
420 Enabling Transparent Hugepage madvise, will only provide a
421 performance improvement benefit to the applications using
422 madvise(MADV_HUGEPAGE) but it won't risk to increase the
423 memory footprint of applications without a guaranteed
424 benefit.
425endchoice
426
427config ARCH_WANTS_THP_SWAP
428 def_bool n
429
430config THP_SWAP
431 def_bool y
432 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP
433 help
434 Swap transparent huge pages in one piece, without splitting.
435 XXX: For now, swap cluster backing transparent huge page
436 will be split after swapout.
437
438 For selection by architectures with reasonable THP sizes.
439
440#
441# UP and nommu archs use km based percpu allocator
442#
443config NEED_PER_CPU_KM
444 depends on !SMP
445 bool
446 default y
447
448config CLEANCACHE
449 bool "Enable cleancache driver to cache clean pages if tmem is present"
450 help
451 Cleancache can be thought of as a page-granularity victim cache
452 for clean pages that the kernel's pageframe replacement algorithm
453 (PFRA) would like to keep around, but can't since there isn't enough
454 memory. So when the PFRA "evicts" a page, it first attempts to use
455 cleancache code to put the data contained in that page into
456 "transcendent memory", memory that is not directly accessible or
457 addressable by the kernel and is of unknown and possibly
458 time-varying size. And when a cleancache-enabled
459 filesystem wishes to access a page in a file on disk, it first
460 checks cleancache to see if it already contains it; if it does,
461 the page is copied into the kernel and a disk access is avoided.
462 When a transcendent memory driver is available (such as zcache or
463 Xen transcendent memory), a significant I/O reduction
464 may be achieved. When none is available, all cleancache calls
465 are reduced to a single pointer-compare-against-NULL resulting
466 in a negligible performance hit.
467
468 If unsure, say Y to enable cleancache
469
470config FRONTSWAP
471 bool "Enable frontswap to cache swap pages if tmem is present"
472 depends on SWAP
473 help
474 Frontswap is so named because it can be thought of as the opposite
475 of a "backing" store for a swap device. The data is stored into
476 "transcendent memory", memory that is not directly accessible or
477 addressable by the kernel and is of unknown and possibly
478 time-varying size. When space in transcendent memory is available,
479 a significant swap I/O reduction may be achieved. When none is
480 available, all frontswap calls are reduced to a single pointer-
481 compare-against-NULL resulting in a negligible performance hit
482 and swap data is stored as normal on the matching swap device.
483
484 If unsure, say Y to enable frontswap.
485
486config CMA
487 bool "Contiguous Memory Allocator"
488 depends on MMU
489 select MIGRATION
490 select MEMORY_ISOLATION
491 help
492 This enables the Contiguous Memory Allocator which allows other
493 subsystems to allocate big physically-contiguous blocks of memory.
494 CMA reserves a region of memory and allows only movable pages to
495 be allocated from it. This way, the kernel can use the memory for
496 pagecache and when a subsystem requests for contiguous area, the
497 allocated pages are migrated away to serve the contiguous request.
498
499 If unsure, say "n".
500
501config CMA_DEBUG
502 bool "CMA debug messages (DEVELOPMENT)"
503 depends on DEBUG_KERNEL && CMA
504 help
505 Turns on debug messages in CMA. This produces KERN_DEBUG
506 messages for every CMA call as well as various messages while
507 processing calls such as dma_alloc_from_contiguous().
508 This option does not affect warning and error messages.
509
510config CMA_DEBUGFS
511 bool "CMA debugfs interface"
512 depends on CMA && DEBUG_FS
513 help
514 Turns on the DebugFS interface for CMA.
515
516config CMA_AREAS
517 int "Maximum count of the CMA areas"
518 depends on CMA
519 default 7
520 help
521 CMA allows to create CMA areas for particular purpose, mainly,
522 used as device private area. This parameter sets the maximum
523 number of CMA area in the system.
524
525 If unsure, leave the default value "7".
526
527config MEM_SOFT_DIRTY
528 bool "Track memory changes"
529 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
530 select PROC_PAGE_MONITOR
531 help
532 This option enables memory changes tracking by introducing a
533 soft-dirty bit on pte-s. This bit it set when someone writes
534 into a page just as regular dirty bit, but unlike the latter
535 it can be cleared by hands.
536
537 See Documentation/admin-guide/mm/soft-dirty.rst for more details.
538
539config ZSWAP
540 bool "Compressed cache for swap pages (EXPERIMENTAL)"
541 depends on FRONTSWAP && CRYPTO=y
542 select ZPOOL
543 help
544 A lightweight compressed cache for swap pages. It takes
545 pages that are in the process of being swapped out and attempts to
546 compress them into a dynamically allocated RAM-based memory pool.
547 This can result in a significant I/O reduction on swap device and,
548 in the case where decompressing from RAM is faster that swap device
549 reads, can also improve workload performance.
550
551 This is marked experimental because it is a new feature (as of
552 v3.11) that interacts heavily with memory reclaim. While these
553 interactions don't cause any known issues on simple memory setups,
554 they have not be fully explored on the large set of potential
555 configurations and workloads that exist.
556
557choice
558 prompt "Compressed cache for swap pages default compressor"
559 depends on ZSWAP
560 default ZSWAP_COMPRESSOR_DEFAULT_LZO
561 help
562 Selects the default compression algorithm for the compressed cache
563 for swap pages.
564
565 For an overview what kind of performance can be expected from
566 a particular compression algorithm please refer to the benchmarks
567 available at the following LWN page:
568 https://lwn.net/Articles/751795/
569
570 If in doubt, select 'LZO'.
571
572 The selection made here can be overridden by using the kernel
573 command line 'zswap.compressor=' option.
574
575config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
576 bool "Deflate"
577 select CRYPTO_DEFLATE
578 help
579 Use the Deflate algorithm as the default compression algorithm.
580
581config ZSWAP_COMPRESSOR_DEFAULT_LZO
582 bool "LZO"
583 select CRYPTO_LZO
584 help
585 Use the LZO algorithm as the default compression algorithm.
586
587config ZSWAP_COMPRESSOR_DEFAULT_842
588 bool "842"
589 select CRYPTO_842
590 help
591 Use the 842 algorithm as the default compression algorithm.
592
593config ZSWAP_COMPRESSOR_DEFAULT_LZ4
594 bool "LZ4"
595 select CRYPTO_LZ4
596 help
597 Use the LZ4 algorithm as the default compression algorithm.
598
599config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
600 bool "LZ4HC"
601 select CRYPTO_LZ4HC
602 help
603 Use the LZ4HC algorithm as the default compression algorithm.
604
605config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
606 bool "zstd"
607 select CRYPTO_ZSTD
608 help
609 Use the zstd algorithm as the default compression algorithm.
610endchoice
611
612config ZSWAP_COMPRESSOR_DEFAULT
613 string
614 depends on ZSWAP
615 default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
616 default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO
617 default "842" if ZSWAP_COMPRESSOR_DEFAULT_842
618 default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4
619 default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
620 default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
621 default ""
622
623choice
624 prompt "Compressed cache for swap pages default allocator"
625 depends on ZSWAP
626 default ZSWAP_ZPOOL_DEFAULT_ZBUD
627 help
628 Selects the default allocator for the compressed cache for
629 swap pages.
630 The default is 'zbud' for compatibility, however please do
631 read the description of each of the allocators below before
632 making a right choice.
633
634 The selection made here can be overridden by using the kernel
635 command line 'zswap.zpool=' option.
636
637config ZSWAP_ZPOOL_DEFAULT_ZBUD
638 bool "zbud"
639 select ZBUD
640 help
641 Use the zbud allocator as the default allocator.
642
643config ZSWAP_ZPOOL_DEFAULT_Z3FOLD
644 bool "z3fold"
645 select Z3FOLD
646 help
647 Use the z3fold allocator as the default allocator.
648
649config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
650 bool "zsmalloc"
651 select ZSMALLOC
652 help
653 Use the zsmalloc allocator as the default allocator.
654endchoice
655
656config ZSWAP_ZPOOL_DEFAULT
657 string
658 depends on ZSWAP
659 default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
660 default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD
661 default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
662 default ""
663
664config ZSWAP_DEFAULT_ON
665 bool "Enable the compressed cache for swap pages by default"
666 depends on ZSWAP
667 help
668 If selected, the compressed cache for swap pages will be enabled
669 at boot, otherwise it will be disabled.
670
671 The selection made here can be overridden by using the kernel
672 command line 'zswap.enabled=' option.
673
674config ZPOOL
675 tristate "Common API for compressed memory storage"
676 help
677 Compressed memory storage API. This allows using either zbud or
678 zsmalloc.
679
680config ZBUD
681 tristate "Low (Up to 2x) density storage for compressed pages"
682 help
683 A special purpose allocator for storing compressed pages.
684 It is designed to store up to two compressed pages per physical
685 page. While this design limits storage density, it has simple and
686 deterministic reclaim properties that make it preferable to a higher
687 density approach when reclaim will be used.
688
689config Z3FOLD
690 tristate "Up to 3x density storage for compressed pages"
691 depends on ZPOOL
692 help
693 A special purpose allocator for storing compressed pages.
694 It is designed to store up to three compressed pages per physical
695 page. It is a ZBUD derivative so the simplicity and determinism are
696 still there.
697
698config ZSMALLOC
699 tristate "Memory allocator for compressed pages"
700 depends on MMU
701 help
702 zsmalloc is a slab-based memory allocator designed to store
703 compressed RAM pages. zsmalloc uses virtual memory mapping
704 in order to reduce fragmentation. However, this results in a
705 non-standard allocator interface where a handle, not a pointer, is
706 returned by an alloc(). This handle must be mapped in order to
707 access the allocated space.
708
709config ZSMALLOC_PGTABLE_MAPPING
710 bool "Use page table mapping to access object in zsmalloc"
711 depends on ZSMALLOC=y
712 help
713 By default, zsmalloc uses a copy-based object mapping method to
714 access allocations that span two pages. However, if a particular
715 architecture (ex, ARM) performs VM mapping faster than copying,
716 then you should select this. This causes zsmalloc to use page table
717 mapping rather than copying for object mapping.
718
719 You can check speed with zsmalloc benchmark:
720 https://github.com/spartacus06/zsmapbench
721
722config ZSMALLOC_STAT
723 bool "Export zsmalloc statistics"
724 depends on ZSMALLOC
725 select DEBUG_FS
726 help
727 This option enables code in the zsmalloc to collect various
728 statistics about whats happening in zsmalloc and exports that
729 information to userspace via debugfs.
730 If unsure, say N.
731
732config GENERIC_EARLY_IOREMAP
733 bool
734
735config MAX_STACK_SIZE_MB
736 int "Maximum user stack size for 32-bit processes (MB)"
737 default 80
738 range 8 2048
739 depends on STACK_GROWSUP && (!64BIT || COMPAT)
740 help
741 This is the maximum stack size in Megabytes in the VM layout of 32-bit
742 user processes when the stack grows upwards (currently only on parisc
743 arch). The stack will be located at the highest memory address minus
744 the given value, unless the RLIMIT_STACK hard limit is changed to a
745 smaller value in which case that is used.
746
747 A sane initial value is 80 MB.
748
749config DEFERRED_STRUCT_PAGE_INIT
750 bool "Defer initialisation of struct pages to kthreads"
751 depends on SPARSEMEM
752 depends on !NEED_PER_CPU_KM
753 depends on 64BIT
754 select PADATA
755 help
756 Ordinarily all struct pages are initialised during early boot in a
757 single thread. On very large machines this can take a considerable
758 amount of time. If this option is set, large machines will bring up
759 a subset of memmap at boot and then initialise the rest in parallel.
760 This has a potential performance impact on tasks running early in the
761 lifetime of the system until these kthreads finish the
762 initialisation.
763
764config IDLE_PAGE_TRACKING
765 bool "Enable idle page tracking"
766 depends on SYSFS && MMU
767 select PAGE_EXTENSION if !64BIT
768 help
769 This feature allows to estimate the amount of user pages that have
770 not been touched during a given period of time. This information can
771 be useful to tune memory cgroup limits and/or for job placement
772 within a compute cluster.
773
774 See Documentation/admin-guide/mm/idle_page_tracking.rst for
775 more details.
776
777config ARCH_HAS_PTE_DEVMAP
778 bool
779
780config ZONE_DEVICE
781 bool "Device memory (pmem, HMM, etc...) hotplug support"
782 depends on MEMORY_HOTPLUG
783 depends on MEMORY_HOTREMOVE
784 depends on SPARSEMEM_VMEMMAP
785 depends on ARCH_HAS_PTE_DEVMAP
786 select XARRAY_MULTI
787
788 help
789 Device memory hotplug support allows for establishing pmem,
790 or other device driver discovered memory regions, in the
791 memmap. This allows pfn_to_page() lookups of otherwise
792 "device-physical" addresses which is needed for using a DAX
793 mapping in an O_DIRECT operation, among other things.
794
795 If FS_DAX is enabled, then say Y.
796
797config DEV_PAGEMAP_OPS
798 bool
799
800#
801# Helpers to mirror range of the CPU page tables of a process into device page
802# tables.
803#
804config HMM_MIRROR
805 bool
806 depends on MMU
807
808config DEVICE_PRIVATE
809 bool "Unaddressable device memory (GPU memory, ...)"
810 depends on ZONE_DEVICE
811 select DEV_PAGEMAP_OPS
812
813 help
814 Allows creation of struct pages to represent unaddressable device
815 memory; i.e., memory that is only accessible from the device (or
816 group of devices). You likely also want to select HMM_MIRROR.
817
818config FRAME_VECTOR
819 bool
820
821config ARCH_USES_HIGH_VMA_FLAGS
822 bool
823config ARCH_HAS_PKEYS
824 bool
825
826config PERCPU_STATS
827 bool "Collect percpu memory statistics"
828 help
829 This feature collects and exposes statistics via debugfs. The
830 information includes global and per chunk statistics, which can
831 be used to help understand percpu memory usage.
832
833config GUP_BENCHMARK
834 bool "Enable infrastructure for get_user_pages_fast() benchmarking"
835 help
836 Provides /sys/kernel/debug/gup_benchmark that helps with testing
837 performance of get_user_pages_fast().
838
839 See tools/testing/selftests/vm/gup_benchmark.c
840
841config GUP_GET_PTE_LOW_HIGH
842 bool
843
844config READ_ONLY_THP_FOR_FS
845 bool "Read-only THP for filesystems (EXPERIMENTAL)"
846 depends on TRANSPARENT_HUGEPAGE && SHMEM
847
848 help
849 Allow khugepaged to put read-only file-backed pages in THP.
850
851 This is marked experimental because it is a new feature. Write
852 support of file THPs will be developed in the next few release
853 cycles.
854
855config ARCH_HAS_PTE_SPECIAL
856 bool
857
858#
859# Some architectures require a special hugepage directory format that is
860# required to support multiple hugepage sizes. For example a4fe3ce76
861# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
862# introduced it on powerpc. This allows for a more flexible hugepage
863# pagetable layouts.
864#
865config ARCH_HAS_HUGEPD
866 bool
867
868config MAPPING_DIRTY_HELPERS
869 bool
870
871endmenu
1# SPDX-License-Identifier: GPL-2.0-only
2
3menu "Memory Management options"
4
5#
6# For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
7# add proper SWAP support to them, in which case this can be remove.
8#
9config ARCH_NO_SWAP
10 bool
11
12config ZPOOL
13 bool
14
15menuconfig SWAP
16 bool "Support for paging of anonymous memory (swap)"
17 depends on MMU && BLOCK && !ARCH_NO_SWAP
18 default y
19 help
20 This option allows you to choose whether you want to have support
21 for so called swap devices or swap files in your kernel that are
22 used to provide more virtual memory than the actual RAM present
23 in your computer. If unsure say Y.
24
25config ZSWAP
26 bool "Compressed cache for swap pages"
27 depends on SWAP
28 select FRONTSWAP
29 select CRYPTO
30 select ZPOOL
31 help
32 A lightweight compressed cache for swap pages. It takes
33 pages that are in the process of being swapped out and attempts to
34 compress them into a dynamically allocated RAM-based memory pool.
35 This can result in a significant I/O reduction on swap device and,
36 in the case where decompressing from RAM is faster than swap device
37 reads, can also improve workload performance.
38
39config ZSWAP_DEFAULT_ON
40 bool "Enable the compressed cache for swap pages by default"
41 depends on ZSWAP
42 help
43 If selected, the compressed cache for swap pages will be enabled
44 at boot, otherwise it will be disabled.
45
46 The selection made here can be overridden by using the kernel
47 command line 'zswap.enabled=' option.
48
49choice
50 prompt "Default compressor"
51 depends on ZSWAP
52 default ZSWAP_COMPRESSOR_DEFAULT_LZO
53 help
54 Selects the default compression algorithm for the compressed cache
55 for swap pages.
56
57 For an overview what kind of performance can be expected from
58 a particular compression algorithm please refer to the benchmarks
59 available at the following LWN page:
60 https://lwn.net/Articles/751795/
61
62 If in doubt, select 'LZO'.
63
64 The selection made here can be overridden by using the kernel
65 command line 'zswap.compressor=' option.
66
67config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
68 bool "Deflate"
69 select CRYPTO_DEFLATE
70 help
71 Use the Deflate algorithm as the default compression algorithm.
72
73config ZSWAP_COMPRESSOR_DEFAULT_LZO
74 bool "LZO"
75 select CRYPTO_LZO
76 help
77 Use the LZO algorithm as the default compression algorithm.
78
79config ZSWAP_COMPRESSOR_DEFAULT_842
80 bool "842"
81 select CRYPTO_842
82 help
83 Use the 842 algorithm as the default compression algorithm.
84
85config ZSWAP_COMPRESSOR_DEFAULT_LZ4
86 bool "LZ4"
87 select CRYPTO_LZ4
88 help
89 Use the LZ4 algorithm as the default compression algorithm.
90
91config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
92 bool "LZ4HC"
93 select CRYPTO_LZ4HC
94 help
95 Use the LZ4HC algorithm as the default compression algorithm.
96
97config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
98 bool "zstd"
99 select CRYPTO_ZSTD
100 help
101 Use the zstd algorithm as the default compression algorithm.
102endchoice
103
104config ZSWAP_COMPRESSOR_DEFAULT
105 string
106 depends on ZSWAP
107 default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
108 default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO
109 default "842" if ZSWAP_COMPRESSOR_DEFAULT_842
110 default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4
111 default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
112 default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
113 default ""
114
115choice
116 prompt "Default allocator"
117 depends on ZSWAP
118 default ZSWAP_ZPOOL_DEFAULT_ZBUD
119 help
120 Selects the default allocator for the compressed cache for
121 swap pages.
122 The default is 'zbud' for compatibility, however please do
123 read the description of each of the allocators below before
124 making a right choice.
125
126 The selection made here can be overridden by using the kernel
127 command line 'zswap.zpool=' option.
128
129config ZSWAP_ZPOOL_DEFAULT_ZBUD
130 bool "zbud"
131 select ZBUD
132 help
133 Use the zbud allocator as the default allocator.
134
135config ZSWAP_ZPOOL_DEFAULT_Z3FOLD
136 bool "z3fold"
137 select Z3FOLD
138 help
139 Use the z3fold allocator as the default allocator.
140
141config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
142 bool "zsmalloc"
143 select ZSMALLOC
144 help
145 Use the zsmalloc allocator as the default allocator.
146endchoice
147
148config ZSWAP_ZPOOL_DEFAULT
149 string
150 depends on ZSWAP
151 default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
152 default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD
153 default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
154 default ""
155
156config ZBUD
157 tristate "2:1 compression allocator (zbud)"
158 depends on ZSWAP
159 help
160 A special purpose allocator for storing compressed pages.
161 It is designed to store up to two compressed pages per physical
162 page. While this design limits storage density, it has simple and
163 deterministic reclaim properties that make it preferable to a higher
164 density approach when reclaim will be used.
165
166config Z3FOLD
167 tristate "3:1 compression allocator (z3fold)"
168 depends on ZSWAP
169 help
170 A special purpose allocator for storing compressed pages.
171 It is designed to store up to three compressed pages per physical
172 page. It is a ZBUD derivative so the simplicity and determinism are
173 still there.
174
175config ZSMALLOC
176 tristate
177 prompt "N:1 compression allocator (zsmalloc)" if ZSWAP
178 depends on MMU
179 help
180 zsmalloc is a slab-based memory allocator designed to store
181 pages of various compression levels efficiently. It achieves
182 the highest storage density with the least amount of fragmentation.
183
184config ZSMALLOC_STAT
185 bool "Export zsmalloc statistics"
186 depends on ZSMALLOC
187 select DEBUG_FS
188 help
189 This option enables code in the zsmalloc to collect various
190 statistics about what's happening in zsmalloc and exports that
191 information to userspace via debugfs.
192 If unsure, say N.
193
194menu "SLAB allocator options"
195
196choice
197 prompt "Choose SLAB allocator"
198 default SLUB
199 help
200 This option allows to select a slab allocator.
201
202config SLAB
203 bool "SLAB"
204 depends on !PREEMPT_RT
205 select HAVE_HARDENED_USERCOPY_ALLOCATOR
206 help
207 The regular slab allocator that is established and known to work
208 well in all environments. It organizes cache hot objects in
209 per cpu and per node queues.
210
211config SLUB
212 bool "SLUB (Unqueued Allocator)"
213 select HAVE_HARDENED_USERCOPY_ALLOCATOR
214 help
215 SLUB is a slab allocator that minimizes cache line usage
216 instead of managing queues of cached objects (SLAB approach).
217 Per cpu caching is realized using slabs of objects instead
218 of queues of objects. SLUB can use memory efficiently
219 and has enhanced diagnostics. SLUB is the default choice for
220 a slab allocator.
221
222config SLOB_DEPRECATED
223 depends on EXPERT
224 bool "SLOB (Simple Allocator - DEPRECATED)"
225 depends on !PREEMPT_RT
226 help
227 Deprecated and scheduled for removal in a few cycles. SLUB
228 recommended as replacement. CONFIG_SLUB_TINY can be considered
229 on systems with 16MB or less RAM.
230
231 If you need SLOB to stay, please contact linux-mm@kvack.org and
232 people listed in the SLAB ALLOCATOR section of MAINTAINERS file,
233 with your use case.
234
235 SLOB replaces the stock allocator with a drastically simpler
236 allocator. SLOB is generally more space efficient but
237 does not perform as well on large systems.
238
239endchoice
240
241config SLOB
242 bool
243 default y
244 depends on SLOB_DEPRECATED
245
246config SLUB_TINY
247 bool "Configure SLUB for minimal memory footprint"
248 depends on SLUB && EXPERT
249 select SLAB_MERGE_DEFAULT
250 help
251 Configures the SLUB allocator in a way to achieve minimal memory
252 footprint, sacrificing scalability, debugging and other features.
253 This is intended only for the smallest system that had used the
254 SLOB allocator and is not recommended for systems with more than
255 16MB RAM.
256
257 If unsure, say N.
258
259config SLAB_MERGE_DEFAULT
260 bool "Allow slab caches to be merged"
261 default y
262 depends on SLAB || SLUB
263 help
264 For reduced kernel memory fragmentation, slab caches can be
265 merged when they share the same size and other characteristics.
266 This carries a risk of kernel heap overflows being able to
267 overwrite objects from merged caches (and more easily control
268 cache layout), which makes such heap attacks easier to exploit
269 by attackers. By keeping caches unmerged, these kinds of exploits
270 can usually only damage objects in the same cache. To disable
271 merging at runtime, "slab_nomerge" can be passed on the kernel
272 command line.
273
274config SLAB_FREELIST_RANDOM
275 bool "Randomize slab freelist"
276 depends on SLAB || (SLUB && !SLUB_TINY)
277 help
278 Randomizes the freelist order used on creating new pages. This
279 security feature reduces the predictability of the kernel slab
280 allocator against heap overflows.
281
282config SLAB_FREELIST_HARDENED
283 bool "Harden slab freelist metadata"
284 depends on SLAB || (SLUB && !SLUB_TINY)
285 help
286 Many kernel heap attacks try to target slab cache metadata and
287 other infrastructure. This options makes minor performance
288 sacrifices to harden the kernel slab allocator against common
289 freelist exploit methods. Some slab implementations have more
290 sanity-checking than others. This option is most effective with
291 CONFIG_SLUB.
292
293config SLUB_STATS
294 default n
295 bool "Enable SLUB performance statistics"
296 depends on SLUB && SYSFS && !SLUB_TINY
297 help
298 SLUB statistics are useful to debug SLUBs allocation behavior in
299 order find ways to optimize the allocator. This should never be
300 enabled for production use since keeping statistics slows down
301 the allocator by a few percentage points. The slabinfo command
302 supports the determination of the most active slabs to figure
303 out which slabs are relevant to a particular load.
304 Try running: slabinfo -DA
305
306config SLUB_CPU_PARTIAL
307 default y
308 depends on SLUB && SMP && !SLUB_TINY
309 bool "SLUB per cpu partial cache"
310 help
311 Per cpu partial caches accelerate objects allocation and freeing
312 that is local to a processor at the price of more indeterminism
313 in the latency of the free. On overflow these caches will be cleared
314 which requires the taking of locks that may cause latency spikes.
315 Typically one would choose no for a realtime system.
316
317endmenu # SLAB allocator options
318
319config SHUFFLE_PAGE_ALLOCATOR
320 bool "Page allocator randomization"
321 default SLAB_FREELIST_RANDOM && ACPI_NUMA
322 help
323 Randomization of the page allocator improves the average
324 utilization of a direct-mapped memory-side-cache. See section
325 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
326 6.2a specification for an example of how a platform advertises
327 the presence of a memory-side-cache. There are also incidental
328 security benefits as it reduces the predictability of page
329 allocations to compliment SLAB_FREELIST_RANDOM, but the
330 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
331 10th order of pages is selected based on cache utilization
332 benefits on x86.
333
334 While the randomization improves cache utilization it may
335 negatively impact workloads on platforms without a cache. For
336 this reason, by default, the randomization is enabled only
337 after runtime detection of a direct-mapped memory-side-cache.
338 Otherwise, the randomization may be force enabled with the
339 'page_alloc.shuffle' kernel command line parameter.
340
341 Say Y if unsure.
342
343config COMPAT_BRK
344 bool "Disable heap randomization"
345 default y
346 help
347 Randomizing heap placement makes heap exploits harder, but it
348 also breaks ancient binaries (including anything libc5 based).
349 This option changes the bootup default to heap randomization
350 disabled, and can be overridden at runtime by setting
351 /proc/sys/kernel/randomize_va_space to 2.
352
353 On non-ancient distros (post-2000 ones) N is usually a safe choice.
354
355config MMAP_ALLOW_UNINITIALIZED
356 bool "Allow mmapped anonymous memory to be uninitialized"
357 depends on EXPERT && !MMU
358 default n
359 help
360 Normally, and according to the Linux spec, anonymous memory obtained
361 from mmap() has its contents cleared before it is passed to
362 userspace. Enabling this config option allows you to request that
363 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
364 providing a huge performance boost. If this option is not enabled,
365 then the flag will be ignored.
366
367 This is taken advantage of by uClibc's malloc(), and also by
368 ELF-FDPIC binfmt's brk and stack allocator.
369
370 Because of the obvious security issues, this option should only be
371 enabled on embedded devices where you control what is run in
372 userspace. Since that isn't generally a problem on no-MMU systems,
373 it is normally safe to say Y here.
374
375 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
376
377config SELECT_MEMORY_MODEL
378 def_bool y
379 depends on ARCH_SELECT_MEMORY_MODEL
380
381choice
382 prompt "Memory model"
383 depends on SELECT_MEMORY_MODEL
384 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
385 default FLATMEM_MANUAL
386 help
387 This option allows you to change some of the ways that
388 Linux manages its memory internally. Most users will
389 only have one option here selected by the architecture
390 configuration. This is normal.
391
392config FLATMEM_MANUAL
393 bool "Flat Memory"
394 depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
395 help
396 This option is best suited for non-NUMA systems with
397 flat address space. The FLATMEM is the most efficient
398 system in terms of performance and resource consumption
399 and it is the best option for smaller systems.
400
401 For systems that have holes in their physical address
402 spaces and for features like NUMA and memory hotplug,
403 choose "Sparse Memory".
404
405 If unsure, choose this option (Flat Memory) over any other.
406
407config SPARSEMEM_MANUAL
408 bool "Sparse Memory"
409 depends on ARCH_SPARSEMEM_ENABLE
410 help
411 This will be the only option for some systems, including
412 memory hot-plug systems. This is normal.
413
414 This option provides efficient support for systems with
415 holes is their physical address space and allows memory
416 hot-plug and hot-remove.
417
418 If unsure, choose "Flat Memory" over this option.
419
420endchoice
421
422config SPARSEMEM
423 def_bool y
424 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
425
426config FLATMEM
427 def_bool y
428 depends on !SPARSEMEM || FLATMEM_MANUAL
429
430#
431# SPARSEMEM_EXTREME (which is the default) does some bootmem
432# allocations when sparse_init() is called. If this cannot
433# be done on your architecture, select this option. However,
434# statically allocating the mem_section[] array can potentially
435# consume vast quantities of .bss, so be careful.
436#
437# This option will also potentially produce smaller runtime code
438# with gcc 3.4 and later.
439#
440config SPARSEMEM_STATIC
441 bool
442
443#
444# Architecture platforms which require a two level mem_section in SPARSEMEM
445# must select this option. This is usually for architecture platforms with
446# an extremely sparse physical address space.
447#
448config SPARSEMEM_EXTREME
449 def_bool y
450 depends on SPARSEMEM && !SPARSEMEM_STATIC
451
452config SPARSEMEM_VMEMMAP_ENABLE
453 bool
454
455config SPARSEMEM_VMEMMAP
456 bool "Sparse Memory virtual memmap"
457 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
458 default y
459 help
460 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
461 pfn_to_page and page_to_pfn operations. This is the most
462 efficient option when sufficient kernel resources are available.
463
464config HAVE_MEMBLOCK_PHYS_MAP
465 bool
466
467config HAVE_FAST_GUP
468 depends on MMU
469 bool
470
471# Don't discard allocated memory used to track "memory" and "reserved" memblocks
472# after early boot, so it can still be used to test for validity of memory.
473# Also, memblocks are updated with memory hot(un)plug.
474config ARCH_KEEP_MEMBLOCK
475 bool
476
477# Keep arch NUMA mapping infrastructure post-init.
478config NUMA_KEEP_MEMINFO
479 bool
480
481config MEMORY_ISOLATION
482 bool
483
484# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
485# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
486# /dev/mem.
487config EXCLUSIVE_SYSTEM_RAM
488 def_bool y
489 depends on !DEVMEM || STRICT_DEVMEM
490
491#
492# Only be set on architectures that have completely implemented memory hotplug
493# feature. If you are not sure, don't touch it.
494#
495config HAVE_BOOTMEM_INFO_NODE
496 def_bool n
497
498config ARCH_ENABLE_MEMORY_HOTPLUG
499 bool
500
501config ARCH_ENABLE_MEMORY_HOTREMOVE
502 bool
503
504# eventually, we can have this option just 'select SPARSEMEM'
505menuconfig MEMORY_HOTPLUG
506 bool "Memory hotplug"
507 select MEMORY_ISOLATION
508 depends on SPARSEMEM
509 depends on ARCH_ENABLE_MEMORY_HOTPLUG
510 depends on 64BIT
511 select NUMA_KEEP_MEMINFO if NUMA
512
513if MEMORY_HOTPLUG
514
515config MEMORY_HOTPLUG_DEFAULT_ONLINE
516 bool "Online the newly added memory blocks by default"
517 depends on MEMORY_HOTPLUG
518 help
519 This option sets the default policy setting for memory hotplug
520 onlining policy (/sys/devices/system/memory/auto_online_blocks) which
521 determines what happens to newly added memory regions. Policy setting
522 can always be changed at runtime.
523 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
524
525 Say Y here if you want all hot-plugged memory blocks to appear in
526 'online' state by default.
527 Say N here if you want the default policy to keep all hot-plugged
528 memory blocks in 'offline' state.
529
530config MEMORY_HOTREMOVE
531 bool "Allow for memory hot remove"
532 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
533 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
534 depends on MIGRATION
535
536config MHP_MEMMAP_ON_MEMORY
537 def_bool y
538 depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP
539 depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
540
541endif # MEMORY_HOTPLUG
542
543# Heavily threaded applications may benefit from splitting the mm-wide
544# page_table_lock, so that faults on different parts of the user address
545# space can be handled with less contention: split it at this NR_CPUS.
546# Default to 4 for wider testing, though 8 might be more appropriate.
547# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
548# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
549# SPARC32 allocates multiple pte tables within a single page, and therefore
550# a per-page lock leads to problems when multiple tables need to be locked
551# at the same time (e.g. copy_page_range()).
552# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
553#
554config SPLIT_PTLOCK_CPUS
555 int
556 default "999999" if !MMU
557 default "999999" if ARM && !CPU_CACHE_VIPT
558 default "999999" if PARISC && !PA20
559 default "999999" if SPARC32
560 default "4"
561
562config ARCH_ENABLE_SPLIT_PMD_PTLOCK
563 bool
564
565#
566# support for memory balloon
567config MEMORY_BALLOON
568 bool
569
570#
571# support for memory balloon compaction
572config BALLOON_COMPACTION
573 bool "Allow for balloon memory compaction/migration"
574 def_bool y
575 depends on COMPACTION && MEMORY_BALLOON
576 help
577 Memory fragmentation introduced by ballooning might reduce
578 significantly the number of 2MB contiguous memory blocks that can be
579 used within a guest, thus imposing performance penalties associated
580 with the reduced number of transparent huge pages that could be used
581 by the guest workload. Allowing the compaction & migration for memory
582 pages enlisted as being part of memory balloon devices avoids the
583 scenario aforementioned and helps improving memory defragmentation.
584
585#
586# support for memory compaction
587config COMPACTION
588 bool "Allow for memory compaction"
589 def_bool y
590 select MIGRATION
591 depends on MMU
592 help
593 Compaction is the only memory management component to form
594 high order (larger physically contiguous) memory blocks
595 reliably. The page allocator relies on compaction heavily and
596 the lack of the feature can lead to unexpected OOM killer
597 invocations for high order memory requests. You shouldn't
598 disable this option unless there really is a strong reason for
599 it and then we would be really interested to hear about that at
600 linux-mm@kvack.org.
601
602config COMPACT_UNEVICTABLE_DEFAULT
603 int
604 depends on COMPACTION
605 default 0 if PREEMPT_RT
606 default 1
607
608#
609# support for free page reporting
610config PAGE_REPORTING
611 bool "Free page reporting"
612 def_bool n
613 help
614 Free page reporting allows for the incremental acquisition of
615 free pages from the buddy allocator for the purpose of reporting
616 those pages to another entity, such as a hypervisor, so that the
617 memory can be freed within the host for other uses.
618
619#
620# support for page migration
621#
622config MIGRATION
623 bool "Page migration"
624 def_bool y
625 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
626 help
627 Allows the migration of the physical location of pages of processes
628 while the virtual addresses are not changed. This is useful in
629 two situations. The first is on NUMA systems to put pages nearer
630 to the processors accessing. The second is when allocating huge
631 pages as migration can relocate pages to satisfy a huge page
632 allocation instead of reclaiming.
633
634config DEVICE_MIGRATION
635 def_bool MIGRATION && ZONE_DEVICE
636
637config ARCH_ENABLE_HUGEPAGE_MIGRATION
638 bool
639
640config ARCH_ENABLE_THP_MIGRATION
641 bool
642
643config HUGETLB_PAGE_SIZE_VARIABLE
644 def_bool n
645 help
646 Allows the pageblock_order value to be dynamic instead of just standard
647 HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
648 on a platform.
649
650 Note that the pageblock_order cannot exceed MAX_ORDER - 1 and will be
651 clamped down to MAX_ORDER - 1.
652
653config CONTIG_ALLOC
654 def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
655
656config PHYS_ADDR_T_64BIT
657 def_bool 64BIT
658
659config BOUNCE
660 bool "Enable bounce buffers"
661 default y
662 depends on BLOCK && MMU && HIGHMEM
663 help
664 Enable bounce buffers for devices that cannot access the full range of
665 memory available to the CPU. Enabled by default when HIGHMEM is
666 selected, but you may say n to override this.
667
668config MMU_NOTIFIER
669 bool
670 select SRCU
671 select INTERVAL_TREE
672
673config KSM
674 bool "Enable KSM for page merging"
675 depends on MMU
676 select XXHASH
677 help
678 Enable Kernel Samepage Merging: KSM periodically scans those areas
679 of an application's address space that an app has advised may be
680 mergeable. When it finds pages of identical content, it replaces
681 the many instances by a single page with that content, so
682 saving memory until one or another app needs to modify the content.
683 Recommended for use with KVM, or with other duplicative applications.
684 See Documentation/mm/ksm.rst for more information: KSM is inactive
685 until a program has madvised that an area is MADV_MERGEABLE, and
686 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
687
688config DEFAULT_MMAP_MIN_ADDR
689 int "Low address space to protect from user allocation"
690 depends on MMU
691 default 4096
692 help
693 This is the portion of low virtual memory which should be protected
694 from userspace allocation. Keeping a user from writing to low pages
695 can help reduce the impact of kernel NULL pointer bugs.
696
697 For most ia64, ppc64 and x86 users with lots of address space
698 a value of 65536 is reasonable and should cause no problems.
699 On arm and other archs it should not be higher than 32768.
700 Programs which use vm86 functionality or have some need to map
701 this low address space will need CAP_SYS_RAWIO or disable this
702 protection by setting the value to 0.
703
704 This value can be changed after boot using the
705 /proc/sys/vm/mmap_min_addr tunable.
706
707config ARCH_SUPPORTS_MEMORY_FAILURE
708 bool
709
710config MEMORY_FAILURE
711 depends on MMU
712 depends on ARCH_SUPPORTS_MEMORY_FAILURE
713 bool "Enable recovery from hardware memory errors"
714 select MEMORY_ISOLATION
715 select RAS
716 help
717 Enables code to recover from some memory failures on systems
718 with MCA recovery. This allows a system to continue running
719 even when some of its memory has uncorrected errors. This requires
720 special hardware support and typically ECC memory.
721
722config HWPOISON_INJECT
723 tristate "HWPoison pages injector"
724 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
725 select PROC_PAGE_MONITOR
726
727config NOMMU_INITIAL_TRIM_EXCESS
728 int "Turn on mmap() excess space trimming before booting"
729 depends on !MMU
730 default 1
731 help
732 The NOMMU mmap() frequently needs to allocate large contiguous chunks
733 of memory on which to store mappings, but it can only ask the system
734 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
735 more than it requires. To deal with this, mmap() is able to trim off
736 the excess and return it to the allocator.
737
738 If trimming is enabled, the excess is trimmed off and returned to the
739 system allocator, which can cause extra fragmentation, particularly
740 if there are a lot of transient processes.
741
742 If trimming is disabled, the excess is kept, but not used, which for
743 long-term mappings means that the space is wasted.
744
745 Trimming can be dynamically controlled through a sysctl option
746 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
747 excess pages there must be before trimming should occur, or zero if
748 no trimming is to occur.
749
750 This option specifies the initial value of this option. The default
751 of 1 says that all excess pages should be trimmed.
752
753 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
754
755config ARCH_WANT_GENERAL_HUGETLB
756 bool
757
758config ARCH_WANTS_THP_SWAP
759 def_bool n
760
761menuconfig TRANSPARENT_HUGEPAGE
762 bool "Transparent Hugepage Support"
763 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
764 select COMPACTION
765 select XARRAY_MULTI
766 help
767 Transparent Hugepages allows the kernel to use huge pages and
768 huge tlb transparently to the applications whenever possible.
769 This feature can improve computing performance to certain
770 applications by speeding up page faults during memory
771 allocation, by reducing the number of tlb misses and by speeding
772 up the pagetable walking.
773
774 If memory constrained on embedded, you may want to say N.
775
776if TRANSPARENT_HUGEPAGE
777
778choice
779 prompt "Transparent Hugepage Support sysfs defaults"
780 depends on TRANSPARENT_HUGEPAGE
781 default TRANSPARENT_HUGEPAGE_ALWAYS
782 help
783 Selects the sysfs defaults for Transparent Hugepage Support.
784
785 config TRANSPARENT_HUGEPAGE_ALWAYS
786 bool "always"
787 help
788 Enabling Transparent Hugepage always, can increase the
789 memory footprint of applications without a guaranteed
790 benefit but it will work automatically for all applications.
791
792 config TRANSPARENT_HUGEPAGE_MADVISE
793 bool "madvise"
794 help
795 Enabling Transparent Hugepage madvise, will only provide a
796 performance improvement benefit to the applications using
797 madvise(MADV_HUGEPAGE) but it won't risk to increase the
798 memory footprint of applications without a guaranteed
799 benefit.
800endchoice
801
802config THP_SWAP
803 def_bool y
804 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT
805 help
806 Swap transparent huge pages in one piece, without splitting.
807 XXX: For now, swap cluster backing transparent huge page
808 will be split after swapout.
809
810 For selection by architectures with reasonable THP sizes.
811
812config READ_ONLY_THP_FOR_FS
813 bool "Read-only THP for filesystems (EXPERIMENTAL)"
814 depends on TRANSPARENT_HUGEPAGE && SHMEM
815
816 help
817 Allow khugepaged to put read-only file-backed pages in THP.
818
819 This is marked experimental because it is a new feature. Write
820 support of file THPs will be developed in the next few release
821 cycles.
822
823endif # TRANSPARENT_HUGEPAGE
824
825#
826# UP and nommu archs use km based percpu allocator
827#
828config NEED_PER_CPU_KM
829 depends on !SMP || !MMU
830 bool
831 default y
832
833config NEED_PER_CPU_EMBED_FIRST_CHUNK
834 bool
835
836config NEED_PER_CPU_PAGE_FIRST_CHUNK
837 bool
838
839config USE_PERCPU_NUMA_NODE_ID
840 bool
841
842config HAVE_SETUP_PER_CPU_AREA
843 bool
844
845config FRONTSWAP
846 bool
847
848config CMA
849 bool "Contiguous Memory Allocator"
850 depends on MMU
851 select MIGRATION
852 select MEMORY_ISOLATION
853 help
854 This enables the Contiguous Memory Allocator which allows other
855 subsystems to allocate big physically-contiguous blocks of memory.
856 CMA reserves a region of memory and allows only movable pages to
857 be allocated from it. This way, the kernel can use the memory for
858 pagecache and when a subsystem requests for contiguous area, the
859 allocated pages are migrated away to serve the contiguous request.
860
861 If unsure, say "n".
862
863config CMA_DEBUG
864 bool "CMA debug messages (DEVELOPMENT)"
865 depends on DEBUG_KERNEL && CMA
866 help
867 Turns on debug messages in CMA. This produces KERN_DEBUG
868 messages for every CMA call as well as various messages while
869 processing calls such as dma_alloc_from_contiguous().
870 This option does not affect warning and error messages.
871
872config CMA_DEBUGFS
873 bool "CMA debugfs interface"
874 depends on CMA && DEBUG_FS
875 help
876 Turns on the DebugFS interface for CMA.
877
878config CMA_SYSFS
879 bool "CMA information through sysfs interface"
880 depends on CMA && SYSFS
881 help
882 This option exposes some sysfs attributes to get information
883 from CMA.
884
885config CMA_AREAS
886 int "Maximum count of the CMA areas"
887 depends on CMA
888 default 19 if NUMA
889 default 7
890 help
891 CMA allows to create CMA areas for particular purpose, mainly,
892 used as device private area. This parameter sets the maximum
893 number of CMA area in the system.
894
895 If unsure, leave the default value "7" in UMA and "19" in NUMA.
896
897config MEM_SOFT_DIRTY
898 bool "Track memory changes"
899 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
900 select PROC_PAGE_MONITOR
901 help
902 This option enables memory changes tracking by introducing a
903 soft-dirty bit on pte-s. This bit it set when someone writes
904 into a page just as regular dirty bit, but unlike the latter
905 it can be cleared by hands.
906
907 See Documentation/admin-guide/mm/soft-dirty.rst for more details.
908
909config GENERIC_EARLY_IOREMAP
910 bool
911
912config STACK_MAX_DEFAULT_SIZE_MB
913 int "Default maximum user stack size for 32-bit processes (MB)"
914 default 100
915 range 8 2048
916 depends on STACK_GROWSUP && (!64BIT || COMPAT)
917 help
918 This is the maximum stack size in Megabytes in the VM layout of 32-bit
919 user processes when the stack grows upwards (currently only on parisc
920 arch) when the RLIMIT_STACK hard limit is unlimited.
921
922 A sane initial value is 100 MB.
923
924config DEFERRED_STRUCT_PAGE_INIT
925 bool "Defer initialisation of struct pages to kthreads"
926 depends on SPARSEMEM
927 depends on !NEED_PER_CPU_KM
928 depends on 64BIT
929 select PADATA
930 help
931 Ordinarily all struct pages are initialised during early boot in a
932 single thread. On very large machines this can take a considerable
933 amount of time. If this option is set, large machines will bring up
934 a subset of memmap at boot and then initialise the rest in parallel.
935 This has a potential performance impact on tasks running early in the
936 lifetime of the system until these kthreads finish the
937 initialisation.
938
939config PAGE_IDLE_FLAG
940 bool
941 select PAGE_EXTENSION if !64BIT
942 help
943 This adds PG_idle and PG_young flags to 'struct page'. PTE Accessed
944 bit writers can set the state of the bit in the flags so that PTE
945 Accessed bit readers may avoid disturbance.
946
947config IDLE_PAGE_TRACKING
948 bool "Enable idle page tracking"
949 depends on SYSFS && MMU
950 select PAGE_IDLE_FLAG
951 help
952 This feature allows to estimate the amount of user pages that have
953 not been touched during a given period of time. This information can
954 be useful to tune memory cgroup limits and/or for job placement
955 within a compute cluster.
956
957 See Documentation/admin-guide/mm/idle_page_tracking.rst for
958 more details.
959
960config ARCH_HAS_CACHE_LINE_SIZE
961 bool
962
963config ARCH_HAS_CURRENT_STACK_POINTER
964 bool
965 help
966 In support of HARDENED_USERCOPY performing stack variable lifetime
967 checking, an architecture-agnostic way to find the stack pointer
968 is needed. Once an architecture defines an unsigned long global
969 register alias named "current_stack_pointer", this config can be
970 selected.
971
972config ARCH_HAS_PTE_DEVMAP
973 bool
974
975config ARCH_HAS_ZONE_DMA_SET
976 bool
977
978config ZONE_DMA
979 bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET
980 default y if ARM64 || X86
981
982config ZONE_DMA32
983 bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET
984 depends on !X86_32
985 default y if ARM64
986
987config ZONE_DEVICE
988 bool "Device memory (pmem, HMM, etc...) hotplug support"
989 depends on MEMORY_HOTPLUG
990 depends on MEMORY_HOTREMOVE
991 depends on SPARSEMEM_VMEMMAP
992 depends on ARCH_HAS_PTE_DEVMAP
993 select XARRAY_MULTI
994
995 help
996 Device memory hotplug support allows for establishing pmem,
997 or other device driver discovered memory regions, in the
998 memmap. This allows pfn_to_page() lookups of otherwise
999 "device-physical" addresses which is needed for using a DAX
1000 mapping in an O_DIRECT operation, among other things.
1001
1002 If FS_DAX is enabled, then say Y.
1003
1004#
1005# Helpers to mirror range of the CPU page tables of a process into device page
1006# tables.
1007#
1008config HMM_MIRROR
1009 bool
1010 depends on MMU
1011
1012config GET_FREE_REGION
1013 depends on SPARSEMEM
1014 bool
1015
1016config DEVICE_PRIVATE
1017 bool "Unaddressable device memory (GPU memory, ...)"
1018 depends on ZONE_DEVICE
1019 select GET_FREE_REGION
1020
1021 help
1022 Allows creation of struct pages to represent unaddressable device
1023 memory; i.e., memory that is only accessible from the device (or
1024 group of devices). You likely also want to select HMM_MIRROR.
1025
1026config VMAP_PFN
1027 bool
1028
1029config ARCH_USES_HIGH_VMA_FLAGS
1030 bool
1031config ARCH_HAS_PKEYS
1032 bool
1033
1034config ARCH_USES_PG_ARCH_X
1035 bool
1036 help
1037 Enable the definition of PG_arch_x page flags with x > 1. Only
1038 suitable for 64-bit architectures with CONFIG_FLATMEM or
1039 CONFIG_SPARSEMEM_VMEMMAP enabled, otherwise there may not be
1040 enough room for additional bits in page->flags.
1041
1042config VM_EVENT_COUNTERS
1043 default y
1044 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1045 help
1046 VM event counters are needed for event counts to be shown.
1047 This option allows the disabling of the VM event counters
1048 on EXPERT systems. /proc/vmstat will only show page counts
1049 if VM event counters are disabled.
1050
1051config PERCPU_STATS
1052 bool "Collect percpu memory statistics"
1053 help
1054 This feature collects and exposes statistics via debugfs. The
1055 information includes global and per chunk statistics, which can
1056 be used to help understand percpu memory usage.
1057
1058config GUP_TEST
1059 bool "Enable infrastructure for get_user_pages()-related unit tests"
1060 depends on DEBUG_FS
1061 help
1062 Provides /sys/kernel/debug/gup_test, which in turn provides a way
1063 to make ioctl calls that can launch kernel-based unit tests for
1064 the get_user_pages*() and pin_user_pages*() family of API calls.
1065
1066 These tests include benchmark testing of the _fast variants of
1067 get_user_pages*() and pin_user_pages*(), as well as smoke tests of
1068 the non-_fast variants.
1069
1070 There is also a sub-test that allows running dump_page() on any
1071 of up to eight pages (selected by command line args) within the
1072 range of user-space addresses. These pages are either pinned via
1073 pin_user_pages*(), or pinned via get_user_pages*(), as specified
1074 by other command line arguments.
1075
1076 See tools/testing/selftests/vm/gup_test.c
1077
1078comment "GUP_TEST needs to have DEBUG_FS enabled"
1079 depends on !GUP_TEST && !DEBUG_FS
1080
1081config GUP_GET_PXX_LOW_HIGH
1082 bool
1083
1084config ARCH_HAS_PTE_SPECIAL
1085 bool
1086
1087#
1088# Some architectures require a special hugepage directory format that is
1089# required to support multiple hugepage sizes. For example a4fe3ce76
1090# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
1091# introduced it on powerpc. This allows for a more flexible hugepage
1092# pagetable layouts.
1093#
1094config ARCH_HAS_HUGEPD
1095 bool
1096
1097config MAPPING_DIRTY_HELPERS
1098 bool
1099
1100config KMAP_LOCAL
1101 bool
1102
1103config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1104 bool
1105
1106# struct io_mapping based helper. Selected by drivers that need them
1107config IO_MAPPING
1108 bool
1109
1110config SECRETMEM
1111 default y
1112 bool "Enable memfd_secret() system call" if EXPERT
1113 depends on ARCH_HAS_SET_DIRECT_MAP
1114 help
1115 Enable the memfd_secret() system call with the ability to create
1116 memory areas visible only in the context of the owning process and
1117 not mapped to other processes and other kernel page tables.
1118
1119config ANON_VMA_NAME
1120 bool "Anonymous VMA name support"
1121 depends on PROC_FS && ADVISE_SYSCALLS && MMU
1122
1123 help
1124 Allow naming anonymous virtual memory areas.
1125
1126 This feature allows assigning names to virtual memory areas. Assigned
1127 names can be later retrieved from /proc/pid/maps and /proc/pid/smaps
1128 and help identifying individual anonymous memory areas.
1129 Assigning a name to anonymous virtual memory area might prevent that
1130 area from being merged with adjacent virtual memory areas due to the
1131 difference in their name.
1132
1133config USERFAULTFD
1134 bool "Enable userfaultfd() system call"
1135 depends on MMU
1136 help
1137 Enable the userfaultfd() system call that allows to intercept and
1138 handle page faults in userland.
1139
1140config HAVE_ARCH_USERFAULTFD_WP
1141 bool
1142 help
1143 Arch has userfaultfd write protection support
1144
1145config HAVE_ARCH_USERFAULTFD_MINOR
1146 bool
1147 help
1148 Arch has userfaultfd minor fault support
1149
1150config PTE_MARKER_UFFD_WP
1151 bool "Userfaultfd write protection support for shmem/hugetlbfs"
1152 default y
1153 depends on HAVE_ARCH_USERFAULTFD_WP
1154
1155 help
1156 Allows to create marker PTEs for userfaultfd write protection
1157 purposes. It is required to enable userfaultfd write protection on
1158 file-backed memory types like shmem and hugetlbfs.
1159
1160# multi-gen LRU {
1161config LRU_GEN
1162 bool "Multi-Gen LRU"
1163 depends on MMU
1164 # make sure folio->flags has enough spare bits
1165 depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP
1166 help
1167 A high performance LRU implementation to overcommit memory. See
1168 Documentation/admin-guide/mm/multigen_lru.rst for details.
1169
1170config LRU_GEN_ENABLED
1171 bool "Enable by default"
1172 depends on LRU_GEN
1173 help
1174 This option enables the multi-gen LRU by default.
1175
1176config LRU_GEN_STATS
1177 bool "Full stats for debugging"
1178 depends on LRU_GEN
1179 help
1180 Do not enable this option unless you plan to look at historical stats
1181 from evicted generations for debugging purpose.
1182
1183 This option has a per-memcg and per-node memory overhead.
1184# }
1185
1186source "mm/damon/Kconfig"
1187
1188endmenu