aboutsummaryrefslogtreecommitdiff
path: root/mm/Kconfig
blob: 034d87953600885dbbcdeeb52231377a9b6360c9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
# SPDX-License-Identifier: GPL-2.0-only

menu "Memory Management options"

config SELECT_MEMORY_MODEL
	def_bool y
	depends on ARCH_SELECT_MEMORY_MODEL

choice
	prompt "Memory model"
	depends on SELECT_MEMORY_MODEL
	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
	default FLATMEM_MANUAL
	help
	  This option allows you to change some of the ways that
	  Linux manages its memory internally. Most users will
	  only have one option here selected by the architecture
	  configuration. This is normal.

config FLATMEM_MANUAL
	bool "Flat Memory"
	depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
	help
	  This option is best suited for non-NUMA systems with
	  flat address space. The FLATMEM is the most efficient
	  system in terms of performance and resource consumption
	  and it is the best option for smaller systems.

	  For systems that have holes in their physical address
	  spaces and for features like NUMA and memory hotplug,
	  choose "Sparse Memory".

	  If unsure, choose this option (Flat Memory) over any other.

config SPARSEMEM_MANUAL
	bool "Sparse Memory"
	depends on ARCH_SPARSEMEM_ENABLE
	help
	  This will be the only option for some systems, including
	  memory hot-plug systems.  This is normal.

	  This option provides efficient support for systems with
	  holes is their physical address space and allows memory
	  hot-plug and hot-remove.

	  If unsure, choose "Flat Memory" over this option.

endchoice

config SPARSEMEM
	def_bool y
	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL

config FLATMEM
	def_bool y
	depends on !SPARSEMEM || FLATMEM_MANUAL

#
# SPARSEMEM_EXTREME (which is the default) does some bootmem
# allocations when sparse_init() is called.  If this cannot
# be done on your architecture, select this option.  However,
# statically allocating the mem_section[] array can potentially
# consume vast quantities of .bss, so be careful.
#
# This option will also potentially produce smaller runtime code
# with gcc 3.4 and later.
#
config SPARSEMEM_STATIC
	bool

#
# Architecture platforms which require a two level mem_section in SPARSEMEM
# must select this option. This is usually for architecture platforms with
# an extremely sparse physical address space.
#
config SPARSEMEM_EXTREME
	def_bool y
	depends on SPARSEMEM && !SPARSEMEM_STATIC

config SPARSEMEM_VMEMMAP_ENABLE
	bool

config SPARSEMEM_VMEMMAP
	bool "Sparse Memory virtual memmap"
	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
	default y
	help
	  SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
	  pfn_to_page and page_to_pfn operations.  This is the most
	  efficient option when sufficient kernel resources are available.

config HAVE_MEMBLOCK_PHYS_MAP
	bool

config HAVE_FAST_GUP
	depends on MMU
	bool

# Don't discard allocated memory used to track "memory" and "reserved" memblocks
# after early boot, so it can still be used to test for validity of memory.
# Also, memblocks are updated with memory hot(un)plug.
config ARCH_KEEP_MEMBLOCK
	bool

# Keep arch NUMA mapping infrastructure post-init.
config NUMA_KEEP_MEMINFO
	bool

config MEMORY_ISOLATION
	bool

# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
# /dev/mem.
config EXCLUSIVE_SYSTEM_RAM
	def_bool y
	depends on !DEVMEM || STRICT_DEVMEM

#
# Only be set on architectures that have completely implemented memory hotplug
# feature. If you are not sure, don't touch it.
#
config HAVE_BOOTMEM_INFO_NODE
	def_bool n

config ARCH_ENABLE_MEMORY_HOTPLUG
	bool

# eventually, we can have this option just 'select SPARSEMEM'
config MEMORY_HOTPLUG
	bool "Allow for memory hot-add"
	select MEMORY_ISOLATION
	depends on SPARSEMEM
	depends on ARCH_ENABLE_MEMORY_HOTPLUG
	depends on 64BIT
	select NUMA_KEEP_MEMINFO if NUMA

config MEMORY_HOTPLUG_DEFAULT_ONLINE
	bool "Online the newly added memory blocks by default"
	depends on MEMORY_HOTPLUG
	help
	  This option sets the default policy setting for memory hotplug
	  onlining policy (/sys/devices/system/memory/auto_online_blocks) which
	  determines what happens to newly added memory regions. Policy setting
	  can always be changed at runtime.
	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.

	  Say Y here if you want all hot-plugged memory blocks to appear in
	  'online' state by default.
	  Say N here if you want the default policy to keep all hot-plugged
	  memory blocks in 'offline' state.

config ARCH_ENABLE_MEMORY_HOTREMOVE
	bool

config MEMORY_HOTREMOVE
	bool "Allow for memory hot remove"
	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
	depends on MIGRATION

config MHP_MEMMAP_ON_MEMORY
	def_bool y
	depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP
	depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE

# Heavily threaded applications may benefit from splitting the mm-wide
# page_table_lock, so that faults on different parts of the user address
# space can be handled with less contention: split it at this NR_CPUS.
# Default to 4 for wider testing, though 8 might be more appropriate.
# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
# SPARC32 allocates multiple pte tables within a single page, and therefore
# a per-page lock leads to problems when multiple tables need to be locked
# at the same time (e.g. copy_page_range()).
# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
#
config SPLIT_PTLOCK_CPUS
	int
	default "999999" if !MMU
	default "999999" if ARM && !CPU_CACHE_VIPT
	default "999999" if PARISC && !PA20
	default "999999" if SPARC32
	default "4"

config ARCH_ENABLE_SPLIT_PMD_PTLOCK
	bool

#
# support for memory balloon
config MEMORY_BALLOON
	bool

#
# support for memory balloon compaction
config BALLOON_COMPACTION
	bool "Allow for balloon memory compaction/migration"
	def_bool y
	depends on COMPACTION && MEMORY_BALLOON
	help
	  Memory fragmentation introduced by ballooning might reduce
	  significantly the number of 2MB contiguous memory blocks that can be
	  used within a guest, thus imposing performance penalties associated
	  with the reduced number of transparent huge pages that could be used
	  by the guest workload. Allowing the compaction & migration for memory
	  pages enlisted as being part of memory balloon devices avoids the
	  scenario aforementioned and helps improving memory defragmentation.

#
# support for memory compaction
config COMPACTION
	bool "Allow for memory compaction"
	def_bool y
	select MIGRATION
	depends on MMU
	help
	  Compaction is the only memory management component to form
	  high order (larger physically contiguous) memory blocks
	  reliably. The page allocator relies on compaction heavily and
	  the lack of the feature can lead to unexpected OOM killer
	  invocations for high order memory requests. You shouldn't
	  disable this option unless there really is a strong reason for
	  it and then we would be really interested to hear about that at
	  linux-mm@kvack.org.

#
# support for free page reporting
config PAGE_REPORTING
	bool "Free page reporting"
	def_bool n
	help
	  Free page reporting allows for the incremental acquisition of
	  free pages from the buddy allocator for the purpose of reporting
	  those pages to another entity, such as a hypervisor, so that the
	  memory can be freed within the host for other uses.

#
# support for page migration
#
config MIGRATION
	bool "Page migration"
	def_bool y
	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
	help
	  Allows the migration of the physical location of pages of processes
	  while the virtual addresses are not changed. This is useful in
	  two situations. The first is on NUMA systems to put pages nearer
	  to the processors accessing. The second is when allocating huge
	  pages as migration can relocate pages to satisfy a huge page
	  allocation instead of reclaiming.

config DEVICE_MIGRATION
	def_bool MIGRATION && ZONE_DEVICE

config ARCH_ENABLE_HUGEPAGE_MIGRATION
	bool

config ARCH_ENABLE_THP_MIGRATION
	bool

config HUGETLB_PAGE_SIZE_VARIABLE
	def_bool n
	help
	  Allows the pageblock_order value to be dynamic instead of just standard
	  HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
	  on a platform.

	  Note that the pageblock_order cannot exceed MAX_ORDER - 1 and will be
	  clamped down to MAX_ORDER - 1.

config CONTIG_ALLOC
	def_bool (MEMORY_ISOLATION && COMPACTION) || CMA

config PHYS_ADDR_T_64BIT
	def_bool 64BIT

config BOUNCE
	bool "Enable bounce buffers"
	default y
	depends on BLOCK && MMU && HIGHMEM
	help
	  Enable bounce buffers for devices that cannot access the full range of
	  memory available to the CPU. Enabled by default when HIGHMEM is
	  selected, but you may say n to override this.

config VIRT_TO_BUS
	bool
	help
	  An architecture should select this if it implements the
	  deprecated interface virt_to_bus().  All new architectures
	  should probably not select this.


config MMU_NOTIFIER
	bool
	select SRCU
	select INTERVAL_TREE

config KSM
	bool "Enable KSM for page merging"
	depends on MMU
	select XXHASH
	help
	  Enable Kernel Samepage Merging: KSM periodically scans those areas
	  of an application's address space that an app has advised may be
	  mergeable.  When it finds pages of identical content, it replaces
	  the many instances by a single page with that content, so
	  saving memory until one or another app needs to modify the content.
	  Recommended for use with KVM, or with other duplicative applications.
	  See Documentation/vm/ksm.rst for more information: KSM is inactive
	  until a program has madvised that an area is MADV_MERGEABLE, and
	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).

config DEFAULT_MMAP_MIN_ADDR
	int "Low address space to protect from user allocation"
	depends on MMU
	default 4096
	help
	  This is the portion of low virtual memory which should be protected
	  from userspace allocation.  Keeping a user from writing to low pages
	  can help reduce the impact of kernel NULL pointer bugs.

	  For most ia64, ppc64 and x86 users with lots of address space
	  a value of 65536 is reasonable and should cause no problems.
	  On arm and other archs it should not be higher than 32768.
	  Programs which use vm86 functionality or have some need to map
	  this low address space will need CAP_SYS_RAWIO or disable this
	  protection by setting the value to 0.

	  This value can be changed after boot using the
	  /proc/sys/vm/mmap_min_addr tunable.

config ARCH_SUPPORTS_MEMORY_FAILURE
	bool

config MEMORY_FAILURE
	depends on MMU
	depends on ARCH_SUPPORTS_MEMORY_FAILURE
	bool "Enable recovery from hardware memory errors"
	select MEMORY_ISOLATION
	select RAS
	help
	  Enables code to recover from some memory failures on systems
	  with MCA recovery. This allows a system to continue running
	  even when some of its memory has uncorrected errors. This requires
	  special hardware support and typically ECC memory.

config HWPOISON_INJECT
	tristate "HWPoison pages injector"
	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
	select PROC_PAGE_MONITOR

config NOMMU_INITIAL_TRIM_EXCESS
	int "Turn on mmap() excess space trimming before booting"
	depends on !MMU
	default 1
	help
	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
	  of memory on which to store mappings, but it can only ask the system
	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
	  more than it requires.  To deal with this, mmap() is able to trim off
	  the excess and return it to the allocator.

	  If trimming is enabled, the excess is trimmed off and returned to the
	  system allocator, which can cause extra fragmentation, particularly
	  if there are a lot of transient processes.

	  If trimming is disabled, the excess is kept, but not used, which for
	  long-term mappings means that the space is wasted.

	  Trimming can be dynamically controlled through a sysctl option
	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
	  excess pages there must be before trimming should occur, or zero if
	  no trimming is to occur.

	  This option specifies the initial value of this option.  The default
	  of 1 says that all excess pages should be trimmed.

	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.

config TRANSPARENT_HUGEPAGE
	bool "Transparent Hugepage Support"
	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
	select COMPACTION
	select XARRAY_MULTI
	help
	  Transparent Hugepages allows the kernel to use huge pages and
	  huge tlb transparently to the applications whenever possible.
	  This feature can improve computing performance to certain
	  applications by speeding up page faults during memory
	  allocation, by reducing the number of tlb misses and by speeding
	  up the pagetable walking.

	  If memory constrained on embedded, you may want to say N.

choice
	prompt "Transparent Hugepage Support sysfs defaults"
	depends on TRANSPARENT_HUGEPAGE
	default TRANSPARENT_HUGEPAGE_ALWAYS
	help
	  Selects the sysfs defaults for Transparent Hugepage Support.

	config TRANSPARENT_HUGEPAGE_ALWAYS
		bool "always"
	help
	  Enabling Transparent Hugepage always, can increase the
	  memory footprint of applications without a guaranteed
	  benefit but it will work automatically for all applications.

	config TRANSPARENT_HUGEPAGE_MADVISE
		bool "madvise"
	help
	  Enabling Transparent Hugepage madvise, will only provide a
	  performance improvement benefit to the applications using
	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
	  memory footprint of applications without a guaranteed
	  benefit.
endchoice

config ARCH_WANT_GENERAL_HUGETLB
	bool

config ARCH_WANTS_THP_SWAP
	def_bool n

config THP_SWAP
	def_bool y
	depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP
	help
	  Swap transparent huge pages in one piece, without splitting.
	  XXX: For now, swap cluster backing transparent huge page
	  will be split after swapout.

	  For selection by architectures with reasonable THP sizes.

#
# UP and nommu archs use km based percpu allocator
#
config NEED_PER_CPU_KM
	depends on !SMP || !MMU
	bool
	default y

config NEED_PER_CPU_EMBED_FIRST_CHUNK
	bool

config NEED_PER_CPU_PAGE_FIRST_CHUNK
	bool

config USE_PERCPU_NUMA_NODE_ID
	bool

config HAVE_SETUP_PER_CPU_AREA
	bool

config FRONTSWAP
	bool

config CMA
	bool "Contiguous Memory Allocator"
	depends on MMU
	select MIGRATION
	select MEMORY_ISOLATION
	help
	  This enables the Contiguous Memory Allocator which allows other
	  subsystems to allocate big physically-contiguous blocks of memory.
	  CMA reserves a region of memory and allows only movable pages to
	  be allocated from it. This way, the kernel can use the memory for
	  pagecache and when a subsystem requests for contiguous area, the
	  allocated pages are migrated away to serve the contiguous request.

	  If unsure, say "n".

config CMA_DEBUG
	bool "CMA debug messages (DEVELOPMENT)"
	depends on DEBUG_KERNEL && CMA
	help
	  Turns on debug messages in CMA.  This produces KERN_DEBUG
	  messages for every CMA call as well as various messages while
	  processing calls such as dma_alloc_from_contiguous().
	  This option does not affect warning and error messages.

config CMA_DEBUGFS
	bool "CMA debugfs interface"
	depends on CMA && DEBUG_FS
	help
	  Turns on the DebugFS interface for CMA.

config CMA_SYSFS
	bool "CMA information through sysfs interface"
	depends on CMA && SYSFS
	help
	  This option exposes some sysfs attributes to get information
	  from CMA.

config CMA_AREAS
	int "Maximum count of the CMA areas"
	depends on CMA
	default 19 if NUMA
	default 7
	help
	  CMA allows to create CMA areas for particular purpose, mainly,
	  used as device private area. This parameter sets the maximum
	  number of CMA area in the system.

	  If unsure, leave the default value "7" in UMA and "19" in NUMA.

config MEM_SOFT_DIRTY
	bool "Track memory changes"
	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
	select PROC_PAGE_MONITOR
	help
	  This option enables memory changes tracking by introducing a
	  soft-dirty bit on pte-s. This bit it set when someone writes
	  into a page just as regular dirty bit, but unlike the latter
	  it can be cleared by hands.

	  See Documentation/admin-guide/mm/soft-dirty.rst for more details.

config ZSWAP
	bool "Compressed cache for swap pages (EXPERIMENTAL)"
	depends on SWAP && CRYPTO=y
	select FRONTSWAP
	select ZPOOL
	help
	  A lightweight compressed cache for swap pages.  It takes
	  pages that are in the process of being swapped out and attempts to
	  compress them into a dynamically allocated RAM-based memory pool.
	  This can result in a significant I/O reduction on swap device and,
	  in the case where decompressing from RAM is faster that swap device
	  reads, can also improve workload performance.

	  This is marked experimental because it is a new feature (as of
	  v3.11) that interacts heavily with memory reclaim.  While these
	  interactions don't cause any known issues on simple memory setups,
	  they have not be fully explored on the large set of potential
	  configurations and workloads that exist.

choice
	prompt "Compressed cache for swap pages default compressor"
	depends on ZSWAP
	default ZSWAP_COMPRESSOR_DEFAULT_LZO
	help
	  Selects the default compression algorithm for the compressed cache
	  for swap pages.

	  For an overview what kind of performance can be expected from
	  a particular compression algorithm please refer to the benchmarks
	  available at the following LWN page:
	  https://lwn.net/Articles/751795/

	  If in doubt, select 'LZO'.

	  The selection made here can be overridden by using the kernel
	  command line 'zswap.compressor=' option.

config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
	bool "Deflate"
	select CRYPTO_DEFLATE
	help
	  Use the Deflate algorithm as the default compression algorithm.

config ZSWAP_COMPRESSOR_DEFAULT_LZO
	bool "LZO"
	select CRYPTO_LZO
	help
	  Use the LZO algorithm as the default compression algorithm.

config ZSWAP_COMPRESSOR_DEFAULT_842
	bool "842"
	select CRYPTO_842
	help
	  Use the 842 algorithm as the default compression algorithm.

config ZSWAP_COMPRESSOR_DEFAULT_LZ4
	bool "LZ4"
	select CRYPTO_LZ4
	help
	  Use the LZ4 algorithm as the default compression algorithm.

config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
	bool "LZ4HC"
	select CRYPTO_LZ4HC
	help
	  Use the LZ4HC algorithm as the default compression algorithm.

config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
	bool "zstd"
	select CRYPTO_ZSTD
	help
	  Use the zstd algorithm as the default compression algorithm.
endchoice

config ZSWAP_COMPRESSOR_DEFAULT
       string
       depends on ZSWAP
       default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
       default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO
       default "842" if ZSWAP_COMPRESSOR_DEFAULT_842
       default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4
       default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
       default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
       default ""

choice
	prompt "Compressed cache for swap pages default allocator"
	depends on ZSWAP
	default ZSWAP_ZPOOL_DEFAULT_ZBUD
	help
	  Selects the default allocator for the compressed cache for
	  swap pages.
	  The default is 'zbud' for compatibility, however please do
	  read the description of each of the allocators below before
	  making a right choice.

	  The selection made here can be overridden by using the kernel
	  command line 'zswap.zpool=' option.

config ZSWAP_ZPOOL_DEFAULT_ZBUD
	bool "zbud"
	select ZBUD
	help
	  Use the zbud allocator as the default allocator.

config ZSWAP_ZPOOL_DEFAULT_Z3FOLD
	bool "z3fold"
	select Z3FOLD
	help
	  Use the z3fold allocator as the default allocator.

config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
	bool "zsmalloc"
	select ZSMALLOC
	help
	  Use the zsmalloc allocator as the default allocator.
endchoice

config ZSWAP_ZPOOL_DEFAULT
       string
       depends on ZSWAP
       default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
       default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD
       default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
       default ""

config ZSWAP_DEFAULT_ON
	bool "Enable the compressed cache for swap pages by default"
	depends on ZSWAP
	help
	  If selected, the compressed cache for swap pages will be enabled
	  at boot, otherwise it will be disabled.

	  The selection made here can be overridden by using the kernel
	  command line 'zswap.enabled=' option.

config ZPOOL
	tristate "Common API for compressed memory storage"
	help
	  Compressed memory storage API.  This allows using either zbud or
	  zsmalloc.

config ZBUD
	tristate "Low (Up to 2x) density storage for compressed pages"
	depends on ZPOOL
	help
	  A special purpose allocator for storing compressed pages.
	  It is designed to store up to two compressed pages per physical
	  page.  While this design limits storage density, it has simple and
	  deterministic reclaim properties that make it preferable to a higher
	  density approach when reclaim will be used.

config Z3FOLD
	tristate "Up to 3x density storage for compressed pages"
	depends on ZPOOL
	help
	  A special purpose allocator for storing compressed pages.
	  It is designed to store up to three compressed pages per physical
	  page. It is a ZBUD derivative so the simplicity and determinism are
	  still there.

config ZSMALLOC
	tristate "Memory allocator for compressed pages"
	depends on MMU
	help
	  zsmalloc is a slab-based memory allocator designed to store
	  compressed RAM pages.  zsmalloc uses virtual memory mapping
	  in order to reduce fragmentation.  However, this results in a
	  non-standard allocator interface where a handle, not a pointer, is
	  returned by an alloc().  This handle must be mapped in order to
	  access the allocated space.

config ZSMALLOC_STAT
	bool "Export zsmalloc statistics"
	depends on ZSMALLOC
	select DEBUG_FS
	help
	  This option enables code in the zsmalloc to collect various
	  statistics about what's happening in zsmalloc and exports that
	  information to userspace via debugfs.
	  If unsure, say N.

config GENERIC_EARLY_IOREMAP
	bool

config STACK_MAX_DEFAULT_SIZE_MB
	int "Default maximum user stack size for 32-bit processes (MB)"
	default 100
	range 8 2048
	depends on STACK_GROWSUP && (!64BIT || COMPAT)
	help
	  This is the maximum stack size in Megabytes in the VM layout of 32-bit
	  user processes when the stack grows upwards (currently only on parisc
	  arch) when the RLIMIT_STACK hard limit is unlimited.

	  A sane initial value is 100 MB.

config DEFERRED_STRUCT_PAGE_INIT
	bool "Defer initialisation of struct pages to kthreads"
	depends on SPARSEMEM
	depends on !NEED_PER_CPU_KM
	depends on 64BIT
	select PADATA
	help
	  Ordinarily all struct pages are initialised during early boot in a
	  single thread. On very large machines this can take a considerable
	  amount of time. If this option is set, large machines will bring up
	  a subset of memmap at boot and then initialise the rest in parallel.
	  This has a potential performance impact on tasks running early in the
	  lifetime of the system until these kthreads finish the
	  initialisation.

config PAGE_IDLE_FLAG
	bool
	select PAGE_EXTENSION if !64BIT
	help
	  This adds PG_idle and PG_young flags to 'struct page'.  PTE Accessed
	  bit writers can set the state of the bit in the flags so that PTE
	  Accessed bit readers may avoid disturbance.

config IDLE_PAGE_TRACKING
	bool "Enable idle page tracking"
	depends on SYSFS && MMU
	select PAGE_IDLE_FLAG
	help
	  This feature allows to estimate the amount of user pages that have
	  not been touched during a given period of time. This information can
	  be useful to tune memory cgroup limits and/or for job placement
	  within a compute cluster.

	  See Documentation/admin-guide/mm/idle_page_tracking.rst for
	  more details.

config ARCH_HAS_CACHE_LINE_SIZE
	bool

config ARCH_HAS_CURRENT_STACK_POINTER
	bool
	help
	  In support of HARDENED_USERCOPY performing stack variable lifetime
	  checking, an architecture-agnostic way to find the stack pointer
	  is needed. Once an architecture defines an unsigned long global
	  register alias named "current_stack_pointer", this config can be
	  selected.

config ARCH_HAS_FILTER_PGPROT
	bool

config ARCH_HAS_PTE_DEVMAP
	bool

config ARCH_HAS_ZONE_DMA_SET
	bool

config ZONE_DMA
	bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET
	default y if ARM64 || X86

config ZONE_DMA32
	bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET
	depends on !X86_32
	default y if ARM64

config ZONE_DEVICE
	bool "Device memory (pmem, HMM, etc...) hotplug support"
	depends on MEMORY_HOTPLUG
	depends on MEMORY_HOTREMOVE
	depends on SPARSEMEM_VMEMMAP
	depends on ARCH_HAS_PTE_DEVMAP
	select XARRAY_MULTI

	help
	  Device memory hotplug support allows for establishing pmem,
	  or other device driver discovered memory regions, in the
	  memmap. This allows pfn_to_page() lookups of otherwise
	  "device-physical" addresses which is needed for using a DAX
	  mapping in an O_DIRECT operation, among other things.

	  If FS_DAX is enabled, then say Y.

#
# Helpers to mirror range of the CPU page tables of a process into device page
# tables.
#
config HMM_MIRROR
	bool
	depends on MMU

config DEVICE_PRIVATE
	bool "Unaddressable device memory (GPU memory, ...)"
	depends on ZONE_DEVICE

	help
	  Allows creation of struct pages to represent unaddressable device
	  memory; i.e., memory that is only accessible from the device (or
	  group of devices). You likely also want to select HMM_MIRROR.

config VMAP_PFN
	bool

config ARCH_USES_HIGH_VMA_FLAGS
	bool
config ARCH_HAS_PKEYS
	bool

config PERCPU_STATS
	bool "Collect percpu memory statistics"
	help
	  This feature collects and exposes statistics via debugfs. The
	  information includes global and per chunk statistics, which can
	  be used to help understand percpu memory usage.

config GUP_TEST
	bool "Enable infrastructure for get_user_pages()-related unit tests"
	depends on DEBUG_FS
	help
	  Provides /sys/kernel/debug/gup_test, which in turn provides a way
	  to make ioctl calls that can launch kernel-based unit tests for
	  the get_user_pages*() and pin_user_pages*() family of API calls.

	  These tests include benchmark testing of the _fast variants of
	  get_user_pages*() and pin_user_pages*(), as well as smoke tests of
	  the non-_fast variants.

	  There is also a sub-test that allows running dump_page() on any
	  of up to eight pages (selected by command line args) within the
	  range of user-space addresses. These pages are either pinned via
	  pin_user_pages*(), or pinned via get_user_pages*(), as specified
	  by other command line arguments.

	  See tools/testing/selftests/vm/gup_test.c

comment "GUP_TEST needs to have DEBUG_FS enabled"
	depends on !GUP_TEST && !DEBUG_FS

config GUP_GET_PTE_LOW_HIGH
	bool

config READ_ONLY_THP_FOR_FS
	bool "Read-only THP for filesystems (EXPERIMENTAL)"
	depends on TRANSPARENT_HUGEPAGE && SHMEM

	help
	  Allow khugepaged to put read-only file-backed pages in THP.

	  This is marked experimental because it is a new feature. Write
	  support of file THPs will be developed in the next few release
	  cycles.

config ARCH_HAS_PTE_SPECIAL
	bool

#
# Some architectures require a special hugepage directory format that is
# required to support multiple hugepage sizes. For example a4fe3ce76
# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
# introduced it on powerpc.  This allows for a more flexible hugepage
# pagetable layouts.
#
config ARCH_HAS_HUGEPD
	bool

config MAPPING_DIRTY_HELPERS
        bool

config KMAP_LOCAL
	bool

config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
	bool

# struct io_mapping based helper.  Selected by drivers that need them
config IO_MAPPING
	bool

config SECRETMEM
	def_bool ARCH_HAS_SET_DIRECT_MAP && !EMBEDDED

config ANON_VMA_NAME
	bool "Anonymous VMA name support"
	depends on PROC_FS && ADVISE_SYSCALLS && MMU

	help
	  Allow naming anonymous virtual memory areas.

	  This feature allows assigning names to virtual memory areas. Assigned
	  names can be later retrieved from /proc/pid/maps and /proc/pid/smaps
	  and help identifying individual anonymous memory areas.
	  Assigning a name to anonymous virtual memory area might prevent that
	  area from being merged with adjacent virtual memory areas due to the
	  difference in their name.

source "mm/damon/Kconfig"

endmenu