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

 
 
 
 
  1config SELECT_MEMORY_MODEL
  2	def_bool y
  3	depends on ARCH_SELECT_MEMORY_MODEL
  4
  5choice
  6	prompt "Memory model"
  7	depends on SELECT_MEMORY_MODEL
  8	default DISCONTIGMEM_MANUAL if ARCH_DISCONTIGMEM_DEFAULT
  9	default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
 10	default FLATMEM_MANUAL
 
 
 
 
 
 11
 12config FLATMEM_MANUAL
 13	bool "Flat Memory"
 14	depends on !(ARCH_DISCONTIGMEM_ENABLE || ARCH_SPARSEMEM_ENABLE) || ARCH_FLATMEM_ENABLE
 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: FLATMEM.  This is normal
 19	  and a correct option.
 20
 21	  Some users of more advanced features like NUMA and
 22	  memory hotplug may have different options here.
 23	  DISCONTIGMEM is a more mature, better tested system,
 24	  but is incompatible with memory hotplug and may suffer
 25	  decreased performance over SPARSEMEM.  If unsure between
 26	  "Sparse Memory" and "Discontiguous Memory", choose
 27	  "Discontiguous Memory".
 28
 29	  If unsure, choose this option (Flat Memory) over any other.
 30
 31config DISCONTIGMEM_MANUAL
 32	bool "Discontiguous Memory"
 33	depends on ARCH_DISCONTIGMEM_ENABLE
 34	help
 35	  This option provides enhanced support for discontiguous
 36	  memory systems, over FLATMEM.  These systems have holes
 37	  in their physical address spaces, and this option provides
 38	  more efficient handling of these holes.  However, the vast
 39	  majority of hardware has quite flat address spaces, and
 40	  can have degraded performance from the extra overhead that
 41	  this option imposes.
 42
 43	  Many NUMA configurations will have this as the only option.
 
 
 44
 45	  If unsure, choose "Flat Memory" over this option.
 46
 47config SPARSEMEM_MANUAL
 48	bool "Sparse Memory"
 49	depends on ARCH_SPARSEMEM_ENABLE
 50	help
 51	  This will be the only option for some systems, including
 52	  memory hotplug systems.  This is normal.
 53
 54	  For many other systems, this will be an alternative to
 55	  "Discontiguous Memory".  This option provides some potential
 56	  performance benefits, along with decreased code complexity,
 57	  but it is newer, and more experimental.
 58
 59	  If unsure, choose "Discontiguous Memory" or "Flat Memory"
 60	  over this option.
 61
 62endchoice
 63
 64config DISCONTIGMEM
 65	def_bool y
 66	depends on (!SELECT_MEMORY_MODEL && ARCH_DISCONTIGMEM_ENABLE) || DISCONTIGMEM_MANUAL
 67
 68config SPARSEMEM
 69	def_bool y
 70	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
 71
 72config FLATMEM
 73	def_bool y
 74	depends on (!DISCONTIGMEM && !SPARSEMEM) || FLATMEM_MANUAL
 75
 76config FLAT_NODE_MEM_MAP
 77	def_bool y
 78	depends on !SPARSEMEM
 79
 80#
 81# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
 82# to represent different areas of memory.  This variable allows
 83# those dependencies to exist individually.
 84#
 85config NEED_MULTIPLE_NODES
 86	def_bool y
 87	depends on DISCONTIGMEM || NUMA
 88
 89config HAVE_MEMORY_PRESENT
 90	def_bool y
 91	depends on ARCH_HAVE_MEMORY_PRESENT || SPARSEMEM
 92
 93#
 94# SPARSEMEM_EXTREME (which is the default) does some bootmem
 95# allocations when memory_present() is called.  If this cannot
 96# be done on your architecture, select this option.  However,
 97# statically allocating the mem_section[] array can potentially
 98# consume vast quantities of .bss, so be careful.
 99#
100# This option will also potentially produce smaller runtime code
101# with gcc 3.4 and later.
102#
103config SPARSEMEM_STATIC
104	bool
105
106#
107# Architecture platforms which require a two level mem_section in SPARSEMEM
108# must select this option. This is usually for architecture platforms with
109# an extremely sparse physical address space.
110#
111config SPARSEMEM_EXTREME
112	def_bool y
113	depends on SPARSEMEM && !SPARSEMEM_STATIC
114
115config SPARSEMEM_VMEMMAP_ENABLE
116	bool
117
118config SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
119	def_bool y
120	depends on SPARSEMEM && X86_64
121
122config SPARSEMEM_VMEMMAP
123	bool "Sparse Memory virtual memmap"
124	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
125	default y
126	help
127	 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
128	 pfn_to_page and page_to_pfn operations.  This is the most
129	 efficient option when sufficient kernel resources are available.
130
131config HAVE_MEMBLOCK
132	bool
133
134config HAVE_MEMBLOCK_NODE_MAP
135	bool
136
137config HAVE_MEMBLOCK_PHYS_MAP
138	bool
139
140config HAVE_GENERIC_RCU_GUP
 
141	bool
142
143config ARCH_DISCARD_MEMBLOCK
 
 
 
144	bool
145
146config NO_BOOTMEM
 
147	bool
148
149config MEMORY_ISOLATION
150	bool
151
152config MOVABLE_NODE
153	bool "Enable to assign a node which has only movable memory"
154	depends on HAVE_MEMBLOCK
155	depends on NO_BOOTMEM
156	depends on X86_64
157	depends on NUMA
158	default n
159	help
160	  Allow a node to have only movable memory.  Pages used by the kernel,
161	  such as direct mapping pages cannot be migrated.  So the corresponding
162	  memory device cannot be hotplugged.  This option allows the following
163	  two things:
164	  - When the system is booting, node full of hotpluggable memory can
165	  be arranged to have only movable memory so that the whole node can
166	  be hot-removed. (need movable_node boot option specified).
167	  - After the system is up, the option allows users to online all the
168	  memory of a node as movable memory so that the whole node can be
169	  hot-removed.
170
171	  Users who don't use the memory hotplug feature are fine with this
172	  option on since they don't specify movable_node boot option or they
173	  don't online memory as movable.
174
175	  Say Y here if you want to hotplug a whole node.
176	  Say N here if you want kernel to use memory on all nodes evenly.
177
178#
179# Only be set on architectures that have completely implemented memory hotplug
180# feature. If you are not sure, don't touch it.
181#
182config HAVE_BOOTMEM_INFO_NODE
183	def_bool n
184
185# eventually, we can have this option just 'select SPARSEMEM'
186config MEMORY_HOTPLUG
187	bool "Allow for memory hot-add"
188	depends on SPARSEMEM || X86_64_ACPI_NUMA
189	depends on ARCH_ENABLE_MEMORY_HOTPLUG
 
 
190
191config MEMORY_HOTPLUG_SPARSE
192	def_bool y
193	depends on SPARSEMEM && MEMORY_HOTPLUG
194
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
195config MEMORY_HOTREMOVE
196	bool "Allow for memory hot remove"
197	select MEMORY_ISOLATION
198	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
199	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
200	depends on MIGRATION
201
202# Heavily threaded applications may benefit from splitting the mm-wide
203# page_table_lock, so that faults on different parts of the user address
204# space can be handled with less contention: split it at this NR_CPUS.
205# Default to 4 for wider testing, though 8 might be more appropriate.
206# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
207# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
 
 
 
208# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
209#
210config SPLIT_PTLOCK_CPUS
211	int
212	default "999999" if !MMU
213	default "999999" if ARM && !CPU_CACHE_VIPT
214	default "999999" if PARISC && !PA20
 
215	default "4"
216
217config ARCH_ENABLE_SPLIT_PMD_PTLOCK
218	bool
219
220#
221# support for memory balloon
222config MEMORY_BALLOON
223	bool
224
225#
226# support for memory balloon compaction
227config BALLOON_COMPACTION
228	bool "Allow for balloon memory compaction/migration"
229	def_bool y
230	depends on COMPACTION && MEMORY_BALLOON
231	help
232	  Memory fragmentation introduced by ballooning might reduce
233	  significantly the number of 2MB contiguous memory blocks that can be
234	  used within a guest, thus imposing performance penalties associated
235	  with the reduced number of transparent huge pages that could be used
236	  by the guest workload. Allowing the compaction & migration for memory
237	  pages enlisted as being part of memory balloon devices avoids the
238	  scenario aforementioned and helps improving memory defragmentation.
239
240#
241# support for memory compaction
242config COMPACTION
243	bool "Allow for memory compaction"
244	def_bool y
245	select MIGRATION
246	depends on MMU
247	help
248	  Allows the compaction of memory for the allocation of huge pages.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
249
250#
251# support for page migration
252#
253config MIGRATION
254	bool "Page migration"
255	def_bool y
256	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
257	help
258	  Allows the migration of the physical location of pages of processes
259	  while the virtual addresses are not changed. This is useful in
260	  two situations. The first is on NUMA systems to put pages nearer
261	  to the processors accessing. The second is when allocating huge
262	  pages as migration can relocate pages to satisfy a huge page
263	  allocation instead of reclaiming.
264
265config ARCH_ENABLE_HUGEPAGE_MIGRATION
266	bool
267
 
 
 
 
 
 
268config PHYS_ADDR_T_64BIT
269	def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
270
271config ZONE_DMA_FLAG
272	int
273	default "0" if !ZONE_DMA
274	default "1"
275
276config BOUNCE
277	bool "Enable bounce buffers"
278	default y
279	depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
280	help
281	  Enable bounce buffers for devices that cannot access
282	  the full range of memory available to the CPU. Enabled
283	  by default when ZONE_DMA or HIGHMEM is selected, but you
284	  may say n to override this.
285
286# On the 'tile' arch, USB OHCI needs the bounce pool since tilegx will often
287# have more than 4GB of memory, but we don't currently use the IOTLB to present
288# a 32-bit address to OHCI.  So we need to use a bounce pool instead.
289config NEED_BOUNCE_POOL
290	bool
291	default y if TILE && USB_OHCI_HCD
292
293config NR_QUICK
294	int
295	depends on QUICKLIST
296	default "2" if AVR32
297	default "1"
298
299config VIRT_TO_BUS
300	bool
301	help
302	  An architecture should select this if it implements the
303	  deprecated interface virt_to_bus().  All new architectures
304	  should probably not select this.
305
306
307config MMU_NOTIFIER
308	bool
309	select SRCU
 
310
311config KSM
312	bool "Enable KSM for page merging"
313	depends on MMU
 
314	help
315	  Enable Kernel Samepage Merging: KSM periodically scans those areas
316	  of an application's address space that an app has advised may be
317	  mergeable.  When it finds pages of identical content, it replaces
318	  the many instances by a single page with that content, so
319	  saving memory until one or another app needs to modify the content.
320	  Recommended for use with KVM, or with other duplicative applications.
321	  See Documentation/vm/ksm.txt for more information: KSM is inactive
322	  until a program has madvised that an area is MADV_MERGEABLE, and
323	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
324
325config DEFAULT_MMAP_MIN_ADDR
326        int "Low address space to protect from user allocation"
327	depends on MMU
328        default 4096
329        help
330	  This is the portion of low virtual memory which should be protected
331	  from userspace allocation.  Keeping a user from writing to low pages
332	  can help reduce the impact of kernel NULL pointer bugs.
333
334	  For most ia64, ppc64 and x86 users with lots of address space
335	  a value of 65536 is reasonable and should cause no problems.
336	  On arm and other archs it should not be higher than 32768.
337	  Programs which use vm86 functionality or have some need to map
338	  this low address space will need CAP_SYS_RAWIO or disable this
339	  protection by setting the value to 0.
340
341	  This value can be changed after boot using the
342	  /proc/sys/vm/mmap_min_addr tunable.
343
344config ARCH_SUPPORTS_MEMORY_FAILURE
345	bool
346
347config MEMORY_FAILURE
348	depends on MMU
349	depends on ARCH_SUPPORTS_MEMORY_FAILURE
350	bool "Enable recovery from hardware memory errors"
351	select MEMORY_ISOLATION
352	select RAS
353	help
354	  Enables code to recover from some memory failures on systems
355	  with MCA recovery. This allows a system to continue running
356	  even when some of its memory has uncorrected errors. This requires
357	  special hardware support and typically ECC memory.
358
359config HWPOISON_INJECT
360	tristate "HWPoison pages injector"
361	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
362	select PROC_PAGE_MONITOR
363
364config NOMMU_INITIAL_TRIM_EXCESS
365	int "Turn on mmap() excess space trimming before booting"
366	depends on !MMU
367	default 1
368	help
369	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
370	  of memory on which to store mappings, but it can only ask the system
371	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
372	  more than it requires.  To deal with this, mmap() is able to trim off
373	  the excess and return it to the allocator.
374
375	  If trimming is enabled, the excess is trimmed off and returned to the
376	  system allocator, which can cause extra fragmentation, particularly
377	  if there are a lot of transient processes.
378
379	  If trimming is disabled, the excess is kept, but not used, which for
380	  long-term mappings means that the space is wasted.
381
382	  Trimming can be dynamically controlled through a sysctl option
383	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
384	  excess pages there must be before trimming should occur, or zero if
385	  no trimming is to occur.
386
387	  This option specifies the initial value of this option.  The default
388	  of 1 says that all excess pages should be trimmed.
389
390	  See Documentation/nommu-mmap.txt for more information.
391
392config TRANSPARENT_HUGEPAGE
393	bool "Transparent Hugepage Support"
394	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
395	select COMPACTION
 
396	help
397	  Transparent Hugepages allows the kernel to use huge pages and
398	  huge tlb transparently to the applications whenever possible.
399	  This feature can improve computing performance to certain
400	  applications by speeding up page faults during memory
401	  allocation, by reducing the number of tlb misses and by speeding
402	  up the pagetable walking.
403
404	  If memory constrained on embedded, you may want to say N.
405
406choice
407	prompt "Transparent Hugepage Support sysfs defaults"
408	depends on TRANSPARENT_HUGEPAGE
409	default TRANSPARENT_HUGEPAGE_ALWAYS
410	help
411	  Selects the sysfs defaults for Transparent Hugepage Support.
412
413	config TRANSPARENT_HUGEPAGE_ALWAYS
414		bool "always"
415	help
416	  Enabling Transparent Hugepage always, can increase the
417	  memory footprint of applications without a guaranteed
418	  benefit but it will work automatically for all applications.
419
420	config TRANSPARENT_HUGEPAGE_MADVISE
421		bool "madvise"
422	help
423	  Enabling Transparent Hugepage madvise, will only provide a
424	  performance improvement benefit to the applications using
425	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
426	  memory footprint of applications without a guaranteed
427	  benefit.
428endchoice
429
 
 
 
 
 
 
 
 
 
 
 
 
 
430#
431# UP and nommu archs use km based percpu allocator
432#
433config NEED_PER_CPU_KM
434	depends on !SMP
435	bool
436	default y
437
438config CLEANCACHE
439	bool "Enable cleancache driver to cache clean pages if tmem is present"
440	default n
441	help
442	  Cleancache can be thought of as a page-granularity victim cache
443	  for clean pages that the kernel's pageframe replacement algorithm
444	  (PFRA) would like to keep around, but can't since there isn't enough
445	  memory.  So when the PFRA "evicts" a page, it first attempts to use
446	  cleancache code to put the data contained in that page into
447	  "transcendent memory", memory that is not directly accessible or
448	  addressable by the kernel and is of unknown and possibly
449	  time-varying size.  And when a cleancache-enabled
450	  filesystem wishes to access a page in a file on disk, it first
451	  checks cleancache to see if it already contains it; if it does,
452	  the page is copied into the kernel and a disk access is avoided.
453	  When a transcendent memory driver is available (such as zcache or
454	  Xen transcendent memory), a significant I/O reduction
455	  may be achieved.  When none is available, all cleancache calls
456	  are reduced to a single pointer-compare-against-NULL resulting
457	  in a negligible performance hit.
458
459	  If unsure, say Y to enable cleancache
460
461config FRONTSWAP
462	bool "Enable frontswap to cache swap pages if tmem is present"
463	depends on SWAP
464	default n
465	help
466	  Frontswap is so named because it can be thought of as the opposite
467	  of a "backing" store for a swap device.  The data is stored into
468	  "transcendent memory", memory that is not directly accessible or
469	  addressable by the kernel and is of unknown and possibly
470	  time-varying size.  When space in transcendent memory is available,
471	  a significant swap I/O reduction may be achieved.  When none is
472	  available, all frontswap calls are reduced to a single pointer-
473	  compare-against-NULL resulting in a negligible performance hit
474	  and swap data is stored as normal on the matching swap device.
475
476	  If unsure, say Y to enable frontswap.
477
478config CMA
479	bool "Contiguous Memory Allocator"
480	depends on HAVE_MEMBLOCK && MMU
481	select MIGRATION
482	select MEMORY_ISOLATION
483	help
484	  This enables the Contiguous Memory Allocator which allows other
485	  subsystems to allocate big physically-contiguous blocks of memory.
486	  CMA reserves a region of memory and allows only movable pages to
487	  be allocated from it. This way, the kernel can use the memory for
488	  pagecache and when a subsystem requests for contiguous area, the
489	  allocated pages are migrated away to serve the contiguous request.
490
491	  If unsure, say "n".
492
493config CMA_DEBUG
494	bool "CMA debug messages (DEVELOPMENT)"
495	depends on DEBUG_KERNEL && CMA
496	help
497	  Turns on debug messages in CMA.  This produces KERN_DEBUG
498	  messages for every CMA call as well as various messages while
499	  processing calls such as dma_alloc_from_contiguous().
500	  This option does not affect warning and error messages.
501
502config CMA_DEBUGFS
503	bool "CMA debugfs interface"
504	depends on CMA && DEBUG_FS
505	help
506	  Turns on the DebugFS interface for CMA.
507
508config CMA_AREAS
509	int "Maximum count of the CMA areas"
510	depends on CMA
511	default 7
512	help
513	  CMA allows to create CMA areas for particular purpose, mainly,
514	  used as device private area. This parameter sets the maximum
515	  number of CMA area in the system.
516
517	  If unsure, leave the default value "7".
518
519config MEM_SOFT_DIRTY
520	bool "Track memory changes"
521	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
522	select PROC_PAGE_MONITOR
523	help
524	  This option enables memory changes tracking by introducing a
525	  soft-dirty bit on pte-s. This bit it set when someone writes
526	  into a page just as regular dirty bit, but unlike the latter
527	  it can be cleared by hands.
528
529	  See Documentation/vm/soft-dirty.txt for more details.
530
531config ZSWAP
532	bool "Compressed cache for swap pages (EXPERIMENTAL)"
533	depends on FRONTSWAP && CRYPTO=y
534	select CRYPTO_LZO
535	select ZPOOL
536	default n
537	help
538	  A lightweight compressed cache for swap pages.  It takes
539	  pages that are in the process of being swapped out and attempts to
540	  compress them into a dynamically allocated RAM-based memory pool.
541	  This can result in a significant I/O reduction on swap device and,
542	  in the case where decompressing from RAM is faster that swap device
543	  reads, can also improve workload performance.
544
545	  This is marked experimental because it is a new feature (as of
546	  v3.11) that interacts heavily with memory reclaim.  While these
547	  interactions don't cause any known issues on simple memory setups,
548	  they have not be fully explored on the large set of potential
549	  configurations and workloads that exist.
550
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
551config ZPOOL
552	tristate "Common API for compressed memory storage"
553	default n
554	help
555	  Compressed memory storage API.  This allows using either zbud or
556	  zsmalloc.
557
558config ZBUD
559	tristate "Low density storage for compressed pages"
560	default n
561	help
562	  A special purpose allocator for storing compressed pages.
563	  It is designed to store up to two compressed pages per physical
564	  page.  While this design limits storage density, it has simple and
565	  deterministic reclaim properties that make it preferable to a higher
566	  density approach when reclaim will be used.
567
 
 
 
 
 
 
 
 
 
568config ZSMALLOC
569	tristate "Memory allocator for compressed pages"
570	depends on MMU
571	default n
572	help
573	  zsmalloc is a slab-based memory allocator designed to store
574	  compressed RAM pages.  zsmalloc uses virtual memory mapping
575	  in order to reduce fragmentation.  However, this results in a
576	  non-standard allocator interface where a handle, not a pointer, is
577	  returned by an alloc().  This handle must be mapped in order to
578	  access the allocated space.
579
580config PGTABLE_MAPPING
581	bool "Use page table mapping to access object in zsmalloc"
582	depends on ZSMALLOC
583	help
584	  By default, zsmalloc uses a copy-based object mapping method to
585	  access allocations that span two pages. However, if a particular
586	  architecture (ex, ARM) performs VM mapping faster than copying,
587	  then you should select this. This causes zsmalloc to use page table
588	  mapping rather than copying for object mapping.
589
590	  You can check speed with zsmalloc benchmark:
591	  https://github.com/spartacus06/zsmapbench
592
593config ZSMALLOC_STAT
594	bool "Export zsmalloc statistics"
595	depends on ZSMALLOC
596	select DEBUG_FS
597	help
598	  This option enables code in the zsmalloc to collect various
599	  statistics about whats happening in zsmalloc and exports that
600	  information to userspace via debugfs.
601	  If unsure, say N.
602
603config GENERIC_EARLY_IOREMAP
604	bool
605
606config MAX_STACK_SIZE_MB
607	int "Maximum user stack size for 32-bit processes (MB)"
608	default 80
609	range 8 256 if METAG
610	range 8 2048
611	depends on STACK_GROWSUP && (!64BIT || COMPAT)
612	help
613	  This is the maximum stack size in Megabytes in the VM layout of 32-bit
614	  user processes when the stack grows upwards (currently only on parisc
615	  and metag arch). The stack will be located at the highest memory
616	  address minus the given value, unless the RLIMIT_STACK hard limit is
617	  changed to a smaller value in which case that is used.
618
619	  A sane initial value is 80 MB.
620
621# For architectures that support deferred memory initialisation
622config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
623	bool
624
625config DEFERRED_STRUCT_PAGE_INIT
626	bool "Defer initialisation of struct pages to kthreads"
627	default n
628	depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
629	depends on MEMORY_HOTPLUG
 
630	help
631	  Ordinarily all struct pages are initialised during early boot in a
632	  single thread. On very large machines this can take a considerable
633	  amount of time. If this option is set, large machines will bring up
634	  a subset of memmap at boot and then initialise the rest in parallel
635	  by starting one-off "pgdatinitX" kernel thread for each node X. This
636	  has a potential performance impact on processes running early in the
637	  lifetime of the system until these kthreads finish the
638	  initialisation.
639
640config IDLE_PAGE_TRACKING
641	bool "Enable idle page tracking"
642	depends on SYSFS && MMU
643	select PAGE_EXTENSION if !64BIT
644	help
645	  This feature allows to estimate the amount of user pages that have
646	  not been touched during a given period of time. This information can
647	  be useful to tune memory cgroup limits and/or for job placement
648	  within a compute cluster.
649
650	  See Documentation/vm/idle_page_tracking.txt for more details.
 
 
 
 
651
652config ZONE_DEVICE
653	bool "Device memory (pmem, etc...) hotplug support" if EXPERT
654	depends on MEMORY_HOTPLUG
655	depends on MEMORY_HOTREMOVE
656	depends on SPARSEMEM_VMEMMAP
657	depends on X86_64 #arch_add_memory() comprehends device memory
 
658
659	help
660	  Device memory hotplug support allows for establishing pmem,
661	  or other device driver discovered memory regions, in the
662	  memmap. This allows pfn_to_page() lookups of otherwise
663	  "device-physical" addresses which is needed for using a DAX
664	  mapping in an O_DIRECT operation, among other things.
665
666	  If FS_DAX is enabled, then say Y.
667
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
668config FRAME_VECTOR
669	bool
670
671config ARCH_USES_HIGH_VMA_FLAGS
672	bool
673config ARCH_HAS_PKEYS
674	bool