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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
91config HAVE_MEMORY_PRESENT
92	def_bool y
93	depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
94
95#
96# SPARSEMEM_EXTREME (which is the default) does some bootmem
97# allocations when memory_present() is called.  If this cannot
98# be done on your architecture, select this option.  However,
99# statically allocating the mem_section[] array can potentially
100# consume vast quantities of .bss, so be careful.
101#
102# This option will also potentially produce smaller runtime code
103# with gcc 3.4 and later.
104#
105config SPARSEMEM_STATIC
106	bool
107
108#
109# Architecture platforms which require a two level mem_section in SPARSEMEM
110# must select this option. This is usually for architecture platforms with
111# an extremely sparse physical address space.
112#
113config SPARSEMEM_EXTREME
114	def_bool y
115	depends on SPARSEMEM && !SPARSEMEM_STATIC
116
117config SPARSEMEM_VMEMMAP_ENABLE
118	bool
119
120config SPARSEMEM_VMEMMAP
121	bool "Sparse Memory virtual memmap"
122	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
123	default y
124	help
125	 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
126	 pfn_to_page and page_to_pfn operations.  This is the most
127	 efficient option when sufficient kernel resources are available.
128
129config HAVE_MEMBLOCK_NODE_MAP
130	bool
131
132config HAVE_MEMBLOCK_PHYS_MAP
133	bool
134
135config HAVE_FAST_GUP
136	depends on MMU
137	bool
138
139config ARCH_KEEP_MEMBLOCK
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
158config MEMORY_HOTPLUG_SPARSE
159	def_bool y
160	depends on SPARSEMEM && MEMORY_HOTPLUG
161
162config MEMORY_HOTPLUG_DEFAULT_ONLINE
163        bool "Online the newly added memory blocks by default"
164        depends on MEMORY_HOTPLUG
165        help
166	  This option sets the default policy setting for memory hotplug
167	  onlining policy (/sys/devices/system/memory/auto_online_blocks) which
168	  determines what happens to newly added memory regions. Policy setting
169	  can always be changed at runtime.
170	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
171
172	  Say Y here if you want all hot-plugged memory blocks to appear in
173	  'online' state by default.
174	  Say N here if you want the default policy to keep all hot-plugged
175	  memory blocks in 'offline' state.
176
177config MEMORY_HOTREMOVE
178	bool "Allow for memory hot remove"
179	select MEMORY_ISOLATION
180	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
181	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
182	depends on MIGRATION
183
184# Heavily threaded applications may benefit from splitting the mm-wide
185# page_table_lock, so that faults on different parts of the user address
186# space can be handled with less contention: split it at this NR_CPUS.
187# Default to 4 for wider testing, though 8 might be more appropriate.
188# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
189# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
190# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
191#
192config SPLIT_PTLOCK_CPUS
193	int
194	default "999999" if !MMU
195	default "999999" if ARM && !CPU_CACHE_VIPT
196	default "999999" if PARISC && !PA20
197	default "4"
198
199config ARCH_ENABLE_SPLIT_PMD_PTLOCK
200	bool
201
202#
203# support for memory balloon
204config MEMORY_BALLOON
205	bool
206
207#
208# support for memory balloon compaction
209config BALLOON_COMPACTION
210	bool "Allow for balloon memory compaction/migration"
211	def_bool y
212	depends on COMPACTION && MEMORY_BALLOON
213	help
214	  Memory fragmentation introduced by ballooning might reduce
215	  significantly the number of 2MB contiguous memory blocks that can be
216	  used within a guest, thus imposing performance penalties associated
217	  with the reduced number of transparent huge pages that could be used
218	  by the guest workload. Allowing the compaction & migration for memory
219	  pages enlisted as being part of memory balloon devices avoids the
220	  scenario aforementioned and helps improving memory defragmentation.
221
222#
223# support for memory compaction
224config COMPACTION
225	bool "Allow for memory compaction"
226	def_bool y
227	select MIGRATION
228	depends on MMU
229	help
230          Compaction is the only memory management component to form
231          high order (larger physically contiguous) memory blocks
232          reliably. The page allocator relies on compaction heavily and
233          the lack of the feature can lead to unexpected OOM killer
234          invocations for high order memory requests. You shouldn't
235          disable this option unless there really is a strong reason for
236          it and then we would be really interested to hear about that at
237          linux-mm@kvack.org.
238
239#
240# support for page migration
241#
242config MIGRATION
243	bool "Page migration"
244	def_bool y
245	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
246	help
247	  Allows the migration of the physical location of pages of processes
248	  while the virtual addresses are not changed. This is useful in
249	  two situations. The first is on NUMA systems to put pages nearer
250	  to the processors accessing. The second is when allocating huge
251	  pages as migration can relocate pages to satisfy a huge page
252	  allocation instead of reclaiming.
253
254config ARCH_ENABLE_HUGEPAGE_MIGRATION
255	bool
256
257config ARCH_ENABLE_THP_MIGRATION
258	bool
259
260config CONTIG_ALLOC
261       def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
262
263config PHYS_ADDR_T_64BIT
264	def_bool 64BIT
265
266config BOUNCE
267	bool "Enable bounce buffers"
268	default y
269	depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
270	help
271	  Enable bounce buffers for devices that cannot access
272	  the full range of memory available to the CPU. Enabled
273	  by default when ZONE_DMA or HIGHMEM is selected, but you
274	  may say n to override this.
275
276config VIRT_TO_BUS
277	bool
278	help
279	  An architecture should select this if it implements the
280	  deprecated interface virt_to_bus().  All new architectures
281	  should probably not select this.
282
283
284config MMU_NOTIFIER
285	bool
286	select SRCU
287
288config KSM
289	bool "Enable KSM for page merging"
290	depends on MMU
291	select XXHASH
292	help
293	  Enable Kernel Samepage Merging: KSM periodically scans those areas
294	  of an application's address space that an app has advised may be
295	  mergeable.  When it finds pages of identical content, it replaces
296	  the many instances by a single page with that content, so
297	  saving memory until one or another app needs to modify the content.
298	  Recommended for use with KVM, or with other duplicative applications.
299	  See Documentation/vm/ksm.rst for more information: KSM is inactive
300	  until a program has madvised that an area is MADV_MERGEABLE, and
301	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
302
303config DEFAULT_MMAP_MIN_ADDR
304        int "Low address space to protect from user allocation"
305	depends on MMU
306        default 4096
307        help
308	  This is the portion of low virtual memory which should be protected
309	  from userspace allocation.  Keeping a user from writing to low pages
310	  can help reduce the impact of kernel NULL pointer bugs.
311
312	  For most ia64, ppc64 and x86 users with lots of address space
313	  a value of 65536 is reasonable and should cause no problems.
314	  On arm and other archs it should not be higher than 32768.
315	  Programs which use vm86 functionality or have some need to map
316	  this low address space will need CAP_SYS_RAWIO or disable this
317	  protection by setting the value to 0.
318
319	  This value can be changed after boot using the
320	  /proc/sys/vm/mmap_min_addr tunable.
321
322config ARCH_SUPPORTS_MEMORY_FAILURE
323	bool
324
325config MEMORY_FAILURE
326	depends on MMU
327	depends on ARCH_SUPPORTS_MEMORY_FAILURE
328	bool "Enable recovery from hardware memory errors"
329	select MEMORY_ISOLATION
330	select RAS
331	help
332	  Enables code to recover from some memory failures on systems
333	  with MCA recovery. This allows a system to continue running
334	  even when some of its memory has uncorrected errors. This requires
335	  special hardware support and typically ECC memory.
336
337config HWPOISON_INJECT
338	tristate "HWPoison pages injector"
339	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
340	select PROC_PAGE_MONITOR
341
342config NOMMU_INITIAL_TRIM_EXCESS
343	int "Turn on mmap() excess space trimming before booting"
344	depends on !MMU
345	default 1
346	help
347	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
348	  of memory on which to store mappings, but it can only ask the system
349	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
350	  more than it requires.  To deal with this, mmap() is able to trim off
351	  the excess and return it to the allocator.
352
353	  If trimming is enabled, the excess is trimmed off and returned to the
354	  system allocator, which can cause extra fragmentation, particularly
355	  if there are a lot of transient processes.
356
357	  If trimming is disabled, the excess is kept, but not used, which for
358	  long-term mappings means that the space is wasted.
359
360	  Trimming can be dynamically controlled through a sysctl option
361	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
362	  excess pages there must be before trimming should occur, or zero if
363	  no trimming is to occur.
364
365	  This option specifies the initial value of this option.  The default
366	  of 1 says that all excess pages should be trimmed.
367
368	  See Documentation/nommu-mmap.txt for more information.
369
370config TRANSPARENT_HUGEPAGE
371	bool "Transparent Hugepage Support"
372	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
373	select COMPACTION
374	select XARRAY_MULTI
375	help
376	  Transparent Hugepages allows the kernel to use huge pages and
377	  huge tlb transparently to the applications whenever possible.
378	  This feature can improve computing performance to certain
379	  applications by speeding up page faults during memory
380	  allocation, by reducing the number of tlb misses and by speeding
381	  up the pagetable walking.
382
383	  If memory constrained on embedded, you may want to say N.
384
385choice
386	prompt "Transparent Hugepage Support sysfs defaults"
387	depends on TRANSPARENT_HUGEPAGE
388	default TRANSPARENT_HUGEPAGE_ALWAYS
389	help
390	  Selects the sysfs defaults for Transparent Hugepage Support.
391
392	config TRANSPARENT_HUGEPAGE_ALWAYS
393		bool "always"
394	help
395	  Enabling Transparent Hugepage always, can increase the
396	  memory footprint of applications without a guaranteed
397	  benefit but it will work automatically for all applications.
398
399	config TRANSPARENT_HUGEPAGE_MADVISE
400		bool "madvise"
401	help
402	  Enabling Transparent Hugepage madvise, will only provide a
403	  performance improvement benefit to the applications using
404	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
405	  memory footprint of applications without a guaranteed
406	  benefit.
407endchoice
408
409config ARCH_WANTS_THP_SWAP
410       def_bool n
411
412config THP_SWAP
413	def_bool y
414	depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP
415	help
416	  Swap transparent huge pages in one piece, without splitting.
417	  XXX: For now, swap cluster backing transparent huge page
418	  will be split after swapout.
419
420	  For selection by architectures with reasonable THP sizes.
421
422config	TRANSPARENT_HUGE_PAGECACHE
423	def_bool y
424	depends on TRANSPARENT_HUGEPAGE
425
426#
427# UP and nommu archs use km based percpu allocator
428#
429config NEED_PER_CPU_KM
430	depends on !SMP
431	bool
432	default y
433
434config CLEANCACHE
435	bool "Enable cleancache driver to cache clean pages if tmem is present"
436	help
437	  Cleancache can be thought of as a page-granularity victim cache
438	  for clean pages that the kernel's pageframe replacement algorithm
439	  (PFRA) would like to keep around, but can't since there isn't enough
440	  memory.  So when the PFRA "evicts" a page, it first attempts to use
441	  cleancache code to put the data contained in that page into
442	  "transcendent memory", memory that is not directly accessible or
443	  addressable by the kernel and is of unknown and possibly
444	  time-varying size.  And when a cleancache-enabled
445	  filesystem wishes to access a page in a file on disk, it first
446	  checks cleancache to see if it already contains it; if it does,
447	  the page is copied into the kernel and a disk access is avoided.
448	  When a transcendent memory driver is available (such as zcache or
449	  Xen transcendent memory), a significant I/O reduction
450	  may be achieved.  When none is available, all cleancache calls
451	  are reduced to a single pointer-compare-against-NULL resulting
452	  in a negligible performance hit.
453
454	  If unsure, say Y to enable cleancache
455
456config FRONTSWAP
457	bool "Enable frontswap to cache swap pages if tmem is present"
458	depends on SWAP
459	help
460	  Frontswap is so named because it can be thought of as the opposite
461	  of a "backing" store for a swap device.  The data is stored into
462	  "transcendent memory", memory that is not directly accessible or
463	  addressable by the kernel and is of unknown and possibly
464	  time-varying size.  When space in transcendent memory is available,
465	  a significant swap I/O reduction may be achieved.  When none is
466	  available, all frontswap calls are reduced to a single pointer-
467	  compare-against-NULL resulting in a negligible performance hit
468	  and swap data is stored as normal on the matching swap device.
469
470	  If unsure, say Y to enable frontswap.
471
472config CMA
473	bool "Contiguous Memory Allocator"
474	depends on MMU
475	select MIGRATION
476	select MEMORY_ISOLATION
477	help
478	  This enables the Contiguous Memory Allocator which allows other
479	  subsystems to allocate big physically-contiguous blocks of memory.
480	  CMA reserves a region of memory and allows only movable pages to
481	  be allocated from it. This way, the kernel can use the memory for
482	  pagecache and when a subsystem requests for contiguous area, the
483	  allocated pages are migrated away to serve the contiguous request.
484
485	  If unsure, say "n".
486
487config CMA_DEBUG
488	bool "CMA debug messages (DEVELOPMENT)"
489	depends on DEBUG_KERNEL && CMA
490	help
491	  Turns on debug messages in CMA.  This produces KERN_DEBUG
492	  messages for every CMA call as well as various messages while
493	  processing calls such as dma_alloc_from_contiguous().
494	  This option does not affect warning and error messages.
495
496config CMA_DEBUGFS
497	bool "CMA debugfs interface"
498	depends on CMA && DEBUG_FS
499	help
500	  Turns on the DebugFS interface for CMA.
501
502config CMA_AREAS
503	int "Maximum count of the CMA areas"
504	depends on CMA
505	default 7
506	help
507	  CMA allows to create CMA areas for particular purpose, mainly,
508	  used as device private area. This parameter sets the maximum
509	  number of CMA area in the system.
510
511	  If unsure, leave the default value "7".
512
513config MEM_SOFT_DIRTY
514	bool "Track memory changes"
515	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
516	select PROC_PAGE_MONITOR
517	help
518	  This option enables memory changes tracking by introducing a
519	  soft-dirty bit on pte-s. This bit it set when someone writes
520	  into a page just as regular dirty bit, but unlike the latter
521	  it can be cleared by hands.
522
523	  See Documentation/admin-guide/mm/soft-dirty.rst for more details.
524
525config ZSWAP
526	bool "Compressed cache for swap pages (EXPERIMENTAL)"
527	depends on FRONTSWAP && CRYPTO=y
528	select CRYPTO_LZO
529	select ZPOOL
530	help
531	  A lightweight compressed cache for swap pages.  It takes
532	  pages that are in the process of being swapped out and attempts to
533	  compress them into a dynamically allocated RAM-based memory pool.
534	  This can result in a significant I/O reduction on swap device and,
535	  in the case where decompressing from RAM is faster that swap device
536	  reads, can also improve workload performance.
537
538	  This is marked experimental because it is a new feature (as of
539	  v3.11) that interacts heavily with memory reclaim.  While these
540	  interactions don't cause any known issues on simple memory setups,
541	  they have not be fully explored on the large set of potential
542	  configurations and workloads that exist.
543
544config ZPOOL
545	tristate "Common API for compressed memory storage"
546	help
547	  Compressed memory storage API.  This allows using either zbud or
548	  zsmalloc.
549
550config ZBUD
551	tristate "Low (Up to 2x) density storage for compressed pages"
552	help
553	  A special purpose allocator for storing compressed pages.
554	  It is designed to store up to two compressed pages per physical
555	  page.  While this design limits storage density, it has simple and
556	  deterministic reclaim properties that make it preferable to a higher
557	  density approach when reclaim will be used.
558
559config Z3FOLD
560	tristate "Up to 3x density storage for compressed pages"
561	depends on ZPOOL
562	help
563	  A special purpose allocator for storing compressed pages.
564	  It is designed to store up to three compressed pages per physical
565	  page. It is a ZBUD derivative so the simplicity and determinism are
566	  still there.
567
568config ZSMALLOC
569	tristate "Memory allocator for compressed pages"
570	depends on MMU
571	help
572	  zsmalloc is a slab-based memory allocator designed to store
573	  compressed RAM pages.  zsmalloc uses virtual memory mapping
574	  in order to reduce fragmentation.  However, this results in a
575	  non-standard allocator interface where a handle, not a pointer, is
576	  returned by an alloc().  This handle must be mapped in order to
577	  access the allocated space.
578
579config ZSMALLOC_STAT
580	bool "Export zsmalloc statistics"
581	depends on ZSMALLOC
582	select DEBUG_FS
583	help
584	  This option enables code in the zsmalloc to collect various
585	  statistics about whats happening in zsmalloc and exports that
586	  information to userspace via debugfs.
587	  If unsure, say N.
588
589config GENERIC_EARLY_IOREMAP
590	bool
591
592config MAX_STACK_SIZE_MB
593	int "Maximum user stack size for 32-bit processes (MB)"
594	default 80
595	range 8 2048
596	depends on STACK_GROWSUP && (!64BIT || COMPAT)
597	help
598	  This is the maximum stack size in Megabytes in the VM layout of 32-bit
599	  user processes when the stack grows upwards (currently only on parisc
600	  arch). The stack will be located at the highest memory address minus
601	  the given value, unless the RLIMIT_STACK hard limit is changed to a
602	  smaller value in which case that is used.
603
604	  A sane initial value is 80 MB.
605
606config DEFERRED_STRUCT_PAGE_INIT
607	bool "Defer initialisation of struct pages to kthreads"
608	depends on SPARSEMEM
609	depends on !NEED_PER_CPU_KM
610	depends on 64BIT
611	help
612	  Ordinarily all struct pages are initialised during early boot in a
613	  single thread. On very large machines this can take a considerable
614	  amount of time. If this option is set, large machines will bring up
615	  a subset of memmap at boot and then initialise the rest in parallel
616	  by starting one-off "pgdatinitX" kernel thread for each node X. This
617	  has a potential performance impact on processes running early in the
618	  lifetime of the system until these kthreads finish the
619	  initialisation.
620
621config IDLE_PAGE_TRACKING
622	bool "Enable idle page tracking"
623	depends on SYSFS && MMU
624	select PAGE_EXTENSION if !64BIT
625	help
626	  This feature allows to estimate the amount of user pages that have
627	  not been touched during a given period of time. This information can
628	  be useful to tune memory cgroup limits and/or for job placement
629	  within a compute cluster.
630
631	  See Documentation/admin-guide/mm/idle_page_tracking.rst for
632	  more details.
633
634config ARCH_HAS_PTE_DEVMAP
635	bool
636
637config ZONE_DEVICE
638	bool "Device memory (pmem, HMM, etc...) hotplug support"
639	depends on MEMORY_HOTPLUG
640	depends on MEMORY_HOTREMOVE
641	depends on SPARSEMEM_VMEMMAP
642	depends on ARCH_HAS_PTE_DEVMAP
643	select XARRAY_MULTI
644
645	help
646	  Device memory hotplug support allows for establishing pmem,
647	  or other device driver discovered memory regions, in the
648	  memmap. This allows pfn_to_page() lookups of otherwise
649	  "device-physical" addresses which is needed for using a DAX
650	  mapping in an O_DIRECT operation, among other things.
651
652	  If FS_DAX is enabled, then say Y.
653
654config DEV_PAGEMAP_OPS
655	bool
656
657#
658# Helpers to mirror range of the CPU page tables of a process into device page
659# tables.
660#
661config HMM_MIRROR
662	bool
663	depends on MMU
664	depends on MMU_NOTIFIER
665
666config DEVICE_PRIVATE
667	bool "Unaddressable device memory (GPU memory, ...)"
668	depends on ZONE_DEVICE
669	select DEV_PAGEMAP_OPS
670
671	help
672	  Allows creation of struct pages to represent unaddressable device
673	  memory; i.e., memory that is only accessible from the device (or
674	  group of devices). You likely also want to select HMM_MIRROR.
675
676config FRAME_VECTOR
677	bool
678
679config ARCH_USES_HIGH_VMA_FLAGS
680	bool
681config ARCH_HAS_PKEYS
682	bool
683
684config PERCPU_STATS
685	bool "Collect percpu memory statistics"
686	help
687	  This feature collects and exposes statistics via debugfs. The
688	  information includes global and per chunk statistics, which can
689	  be used to help understand percpu memory usage.
690
691config GUP_BENCHMARK
692	bool "Enable infrastructure for get_user_pages_fast() benchmarking"
693	help
694	  Provides /sys/kernel/debug/gup_benchmark that helps with testing
695	  performance of get_user_pages_fast().
696
697	  See tools/testing/selftests/vm/gup_benchmark.c
698
699config GUP_GET_PTE_LOW_HIGH
700	bool
701
702config READ_ONLY_THP_FOR_FS
703	bool "Read-only THP for filesystems (EXPERIMENTAL)"
704	depends on TRANSPARENT_HUGE_PAGECACHE && SHMEM
705
706	help
707	  Allow khugepaged to put read-only file-backed pages in THP.
708
709	  This is marked experimental because it is a new feature. Write
710	  support of file THPs will be developed in the next few release
711	  cycles.
712
713config ARCH_HAS_PTE_SPECIAL
714	bool
715
716#
717# Some architectures require a special hugepage directory format that is
718# required to support multiple hugepage sizes. For example a4fe3ce76
719# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
720# introduced it on powerpc.  This allows for a more flexible hugepage
721# pagetable layouts.
722#
723config ARCH_HAS_HUGEPD
724	bool
725
726endmenu
727