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 SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
13	default FLATMEM_MANUAL
14	help
15	  This option allows you to change some of the ways that
16	  Linux manages its memory internally. Most users will
17	  only have one option here selected by the architecture
18	  configuration. This is normal.
19
20config FLATMEM_MANUAL
21	bool "Flat Memory"
22	depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
23	help
24	  This option is best suited for non-NUMA systems with
25	  flat address space. The FLATMEM is the most efficient
26	  system in terms of performance and resource consumption
27	  and it is the best option for smaller systems.
28
29	  For systems that have holes in their physical address
30	  spaces and for features like NUMA and memory hotplug,
31	  choose "Sparse Memory".
32
33	  If unsure, choose this option (Flat Memory) over any other.
34
35config SPARSEMEM_MANUAL
36	bool "Sparse Memory"
37	depends on ARCH_SPARSEMEM_ENABLE
38	help
39	  This will be the only option for some systems, including
40	  memory hot-plug systems.  This is normal.
41
42	  This option provides efficient support for systems with
43	  holes is their physical address space and allows memory
44	  hot-plug and hot-remove.
45
46	  If unsure, choose "Flat Memory" over this option.
47
48endchoice
49
50config SPARSEMEM
51	def_bool y
52	depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
53
54config FLATMEM
55	def_bool y
56	depends on !SPARSEMEM || FLATMEM_MANUAL
57
58#
59# SPARSEMEM_EXTREME (which is the default) does some bootmem
60# allocations when sparse_init() is called.  If this cannot
61# be done on your architecture, select this option.  However,
62# statically allocating the mem_section[] array can potentially
63# consume vast quantities of .bss, so be careful.
64#
65# This option will also potentially produce smaller runtime code
66# with gcc 3.4 and later.
67#
68config SPARSEMEM_STATIC
69	bool
70
71#
72# Architecture platforms which require a two level mem_section in SPARSEMEM
73# must select this option. This is usually for architecture platforms with
74# an extremely sparse physical address space.
75#
76config SPARSEMEM_EXTREME
77	def_bool y
78	depends on SPARSEMEM && !SPARSEMEM_STATIC
79
80config SPARSEMEM_VMEMMAP_ENABLE
81	bool
82
83config SPARSEMEM_VMEMMAP
84	bool "Sparse Memory virtual memmap"
85	depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
86	default y
87	help
88	  SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
89	  pfn_to_page and page_to_pfn operations.  This is the most
90	  efficient option when sufficient kernel resources are available.
91
92config HAVE_MEMBLOCK_PHYS_MAP
93	bool
94
95config HAVE_FAST_GUP
96	depends on MMU
97	bool
98
99# Don't discard allocated memory used to track "memory" and "reserved" memblocks
100# after early boot, so it can still be used to test for validity of memory.
101# Also, memblocks are updated with memory hot(un)plug.
102config ARCH_KEEP_MEMBLOCK
103	bool
104
105# Keep arch NUMA mapping infrastructure post-init.
106config NUMA_KEEP_MEMINFO
107	bool
108
109config MEMORY_ISOLATION
110	bool
111
112# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
113# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
114# /dev/mem.
115config EXCLUSIVE_SYSTEM_RAM
116	def_bool y
117	depends on !DEVMEM || STRICT_DEVMEM
118
119#
120# Only be set on architectures that have completely implemented memory hotplug
121# feature. If you are not sure, don't touch it.
122#
123config HAVE_BOOTMEM_INFO_NODE
124	def_bool n
125
126config ARCH_ENABLE_MEMORY_HOTPLUG
127	bool
128
129# eventually, we can have this option just 'select SPARSEMEM'
130config MEMORY_HOTPLUG
131	bool "Allow for memory hot-add"
132	select MEMORY_ISOLATION
133	depends on SPARSEMEM
134	depends on ARCH_ENABLE_MEMORY_HOTPLUG
135	depends on 64BIT
136	select NUMA_KEEP_MEMINFO if NUMA
137
138config MEMORY_HOTPLUG_DEFAULT_ONLINE
139	bool "Online the newly added memory blocks by default"
140	depends on MEMORY_HOTPLUG
141	help
142	  This option sets the default policy setting for memory hotplug
143	  onlining policy (/sys/devices/system/memory/auto_online_blocks) which
144	  determines what happens to newly added memory regions. Policy setting
145	  can always be changed at runtime.
146	  See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
147
148	  Say Y here if you want all hot-plugged memory blocks to appear in
149	  'online' state by default.
150	  Say N here if you want the default policy to keep all hot-plugged
151	  memory blocks in 'offline' state.
152
153config ARCH_ENABLE_MEMORY_HOTREMOVE
154	bool
155
156config MEMORY_HOTREMOVE
157	bool "Allow for memory hot remove"
158	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
159	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
160	depends on MIGRATION
161
162config MHP_MEMMAP_ON_MEMORY
163	def_bool y
164	depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP
165	depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
166
167# Heavily threaded applications may benefit from splitting the mm-wide
168# page_table_lock, so that faults on different parts of the user address
169# space can be handled with less contention: split it at this NR_CPUS.
170# Default to 4 for wider testing, though 8 might be more appropriate.
171# ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
172# PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
173# SPARC32 allocates multiple pte tables within a single page, and therefore
174# a per-page lock leads to problems when multiple tables need to be locked
175# at the same time (e.g. copy_page_range()).
176# DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
177#
178config SPLIT_PTLOCK_CPUS
179	int
180	default "999999" if !MMU
181	default "999999" if ARM && !CPU_CACHE_VIPT
182	default "999999" if PARISC && !PA20
183	default "999999" if SPARC32
184	default "4"
185
186config ARCH_ENABLE_SPLIT_PMD_PTLOCK
187	bool
188
189#
190# support for memory balloon
191config MEMORY_BALLOON
192	bool
193
194#
195# support for memory balloon compaction
196config BALLOON_COMPACTION
197	bool "Allow for balloon memory compaction/migration"
198	def_bool y
199	depends on COMPACTION && MEMORY_BALLOON
200	help
201	  Memory fragmentation introduced by ballooning might reduce
202	  significantly the number of 2MB contiguous memory blocks that can be
203	  used within a guest, thus imposing performance penalties associated
204	  with the reduced number of transparent huge pages that could be used
205	  by the guest workload. Allowing the compaction & migration for memory
206	  pages enlisted as being part of memory balloon devices avoids the
207	  scenario aforementioned and helps improving memory defragmentation.
208
209#
210# support for memory compaction
211config COMPACTION
212	bool "Allow for memory compaction"
213	def_bool y
214	select MIGRATION
215	depends on MMU
216	help
217	  Compaction is the only memory management component to form
218	  high order (larger physically contiguous) memory blocks
219	  reliably. The page allocator relies on compaction heavily and
220	  the lack of the feature can lead to unexpected OOM killer
221	  invocations for high order memory requests. You shouldn't
222	  disable this option unless there really is a strong reason for
223	  it and then we would be really interested to hear about that at
224	  linux-mm@kvack.org.
225
226#
227# support for free page reporting
228config PAGE_REPORTING
229	bool "Free page reporting"
230	def_bool n
231	help
232	  Free page reporting allows for the incremental acquisition of
233	  free pages from the buddy allocator for the purpose of reporting
234	  those pages to another entity, such as a hypervisor, so that the
235	  memory can be freed within the host for other uses.
236
237#
238# support for page migration
239#
240config MIGRATION
241	bool "Page migration"
242	def_bool y
243	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
244	help
245	  Allows the migration of the physical location of pages of processes
246	  while the virtual addresses are not changed. This is useful in
247	  two situations. The first is on NUMA systems to put pages nearer
248	  to the processors accessing. The second is when allocating huge
249	  pages as migration can relocate pages to satisfy a huge page
250	  allocation instead of reclaiming.
251
252config ARCH_ENABLE_HUGEPAGE_MIGRATION
253	bool
254
255config ARCH_ENABLE_THP_MIGRATION
256	bool
257
258config HUGETLB_PAGE_SIZE_VARIABLE
259	def_bool n
260	help
261	  Allows the pageblock_order value to be dynamic instead of just standard
262	  HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
263	  on a platform.
264
265config CONTIG_ALLOC
266	def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
267
268config PHYS_ADDR_T_64BIT
269	def_bool 64BIT
270
271config BOUNCE
272	bool "Enable bounce buffers"
273	default y
274	depends on BLOCK && MMU && HIGHMEM
275	help
276	  Enable bounce buffers for devices that cannot access the full range of
277	  memory available to the CPU. Enabled by default when HIGHMEM is
278	  selected, but you may say n to override this.
279
280config VIRT_TO_BUS
281	bool
282	help
283	  An architecture should select this if it implements the
284	  deprecated interface virt_to_bus().  All new architectures
285	  should probably not select this.
286
287
288config MMU_NOTIFIER
289	bool
290	select SRCU
291	select INTERVAL_TREE
292
293config KSM
294	bool "Enable KSM for page merging"
295	depends on MMU
296	select XXHASH
297	help
298	  Enable Kernel Samepage Merging: KSM periodically scans those areas
299	  of an application's address space that an app has advised may be
300	  mergeable.  When it finds pages of identical content, it replaces
301	  the many instances by a single page with that content, so
302	  saving memory until one or another app needs to modify the content.
303	  Recommended for use with KVM, or with other duplicative applications.
304	  See Documentation/vm/ksm.rst for more information: KSM is inactive
305	  until a program has madvised that an area is MADV_MERGEABLE, and
306	  root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
307
308config DEFAULT_MMAP_MIN_ADDR
309	int "Low address space to protect from user allocation"
310	depends on MMU
311	default 4096
312	help
313	  This is the portion of low virtual memory which should be protected
314	  from userspace allocation.  Keeping a user from writing to low pages
315	  can help reduce the impact of kernel NULL pointer bugs.
316
317	  For most ia64, ppc64 and x86 users with lots of address space
318	  a value of 65536 is reasonable and should cause no problems.
319	  On arm and other archs it should not be higher than 32768.
320	  Programs which use vm86 functionality or have some need to map
321	  this low address space will need CAP_SYS_RAWIO or disable this
322	  protection by setting the value to 0.
323
324	  This value can be changed after boot using the
325	  /proc/sys/vm/mmap_min_addr tunable.
326
327config ARCH_SUPPORTS_MEMORY_FAILURE
328	bool
329
330config MEMORY_FAILURE
331	depends on MMU
332	depends on ARCH_SUPPORTS_MEMORY_FAILURE
333	bool "Enable recovery from hardware memory errors"
334	select MEMORY_ISOLATION
335	select RAS
336	help
337	  Enables code to recover from some memory failures on systems
338	  with MCA recovery. This allows a system to continue running
339	  even when some of its memory has uncorrected errors. This requires
340	  special hardware support and typically ECC memory.
341
342config HWPOISON_INJECT
343	tristate "HWPoison pages injector"
344	depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
345	select PROC_PAGE_MONITOR
346
347config NOMMU_INITIAL_TRIM_EXCESS
348	int "Turn on mmap() excess space trimming before booting"
349	depends on !MMU
350	default 1
351	help
352	  The NOMMU mmap() frequently needs to allocate large contiguous chunks
353	  of memory on which to store mappings, but it can only ask the system
354	  allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
355	  more than it requires.  To deal with this, mmap() is able to trim off
356	  the excess and return it to the allocator.
357
358	  If trimming is enabled, the excess is trimmed off and returned to the
359	  system allocator, which can cause extra fragmentation, particularly
360	  if there are a lot of transient processes.
361
362	  If trimming is disabled, the excess is kept, but not used, which for
363	  long-term mappings means that the space is wasted.
364
365	  Trimming can be dynamically controlled through a sysctl option
366	  (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
367	  excess pages there must be before trimming should occur, or zero if
368	  no trimming is to occur.
369
370	  This option specifies the initial value of this option.  The default
371	  of 1 says that all excess pages should be trimmed.
372
373	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
374
375config TRANSPARENT_HUGEPAGE
376	bool "Transparent Hugepage Support"
377	depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
378	select COMPACTION
379	select XARRAY_MULTI
380	help
381	  Transparent Hugepages allows the kernel to use huge pages and
382	  huge tlb transparently to the applications whenever possible.
383	  This feature can improve computing performance to certain
384	  applications by speeding up page faults during memory
385	  allocation, by reducing the number of tlb misses and by speeding
386	  up the pagetable walking.
387
388	  If memory constrained on embedded, you may want to say N.
389
390choice
391	prompt "Transparent Hugepage Support sysfs defaults"
392	depends on TRANSPARENT_HUGEPAGE
393	default TRANSPARENT_HUGEPAGE_ALWAYS
394	help
395	  Selects the sysfs defaults for Transparent Hugepage Support.
396
397	config TRANSPARENT_HUGEPAGE_ALWAYS
398		bool "always"
399	help
400	  Enabling Transparent Hugepage always, can increase the
401	  memory footprint of applications without a guaranteed
402	  benefit but it will work automatically for all applications.
403
404	config TRANSPARENT_HUGEPAGE_MADVISE
405		bool "madvise"
406	help
407	  Enabling Transparent Hugepage madvise, will only provide a
408	  performance improvement benefit to the applications using
409	  madvise(MADV_HUGEPAGE) but it won't risk to increase the
410	  memory footprint of applications without a guaranteed
411	  benefit.
412endchoice
413
414config ARCH_WANTS_THP_SWAP
415	def_bool n
416
417config THP_SWAP
418	def_bool y
419	depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP
420	help
421	  Swap transparent huge pages in one piece, without splitting.
422	  XXX: For now, swap cluster backing transparent huge page
423	  will be split after swapout.
424
425	  For selection by architectures with reasonable THP sizes.
426
427#
428# UP and nommu archs use km based percpu allocator
429#
430config NEED_PER_CPU_KM
431	depends on !SMP || !MMU
432	bool
433	default y
434
435config CLEANCACHE
436	bool "Enable cleancache driver to cache clean pages if tmem is present"
437	help
438	  Cleancache can be thought of as a page-granularity victim cache
439	  for clean pages that the kernel's pageframe replacement algorithm
440	  (PFRA) would like to keep around, but can't since there isn't enough
441	  memory.  So when the PFRA "evicts" a page, it first attempts to use
442	  cleancache code to put the data contained in that page into
443	  "transcendent memory", memory that is not directly accessible or
444	  addressable by the kernel and is of unknown and possibly
445	  time-varying size.  And when a cleancache-enabled
446	  filesystem wishes to access a page in a file on disk, it first
447	  checks cleancache to see if it already contains it; if it does,
448	  the page is copied into the kernel and a disk access is avoided.
449	  When a transcendent memory driver is available (such as zcache or
450	  Xen transcendent memory), a significant I/O reduction
451	  may be achieved.  When none is available, all cleancache calls
452	  are reduced to a single pointer-compare-against-NULL resulting
453	  in a negligible performance hit.
454
455	  If unsure, say Y to enable cleancache
456
457config FRONTSWAP
458	bool "Enable frontswap to cache swap pages if tmem is present"
459	depends on SWAP
460	help
461	  Frontswap is so named because it can be thought of as the opposite
462	  of a "backing" store for a swap device.  The data is stored into
463	  "transcendent memory", memory that is not directly accessible or
464	  addressable by the kernel and is of unknown and possibly
465	  time-varying size.  When space in transcendent memory is available,
466	  a significant swap I/O reduction may be achieved.  When none is
467	  available, all frontswap calls are reduced to a single pointer-
468	  compare-against-NULL resulting in a negligible performance hit
469	  and swap data is stored as normal on the matching swap device.
470
471	  If unsure, say Y to enable frontswap.
472
473config CMA
474	bool "Contiguous Memory Allocator"
475	depends on MMU
476	select MIGRATION
477	select MEMORY_ISOLATION
478	help
479	  This enables the Contiguous Memory Allocator which allows other
480	  subsystems to allocate big physically-contiguous blocks of memory.
481	  CMA reserves a region of memory and allows only movable pages to
482	  be allocated from it. This way, the kernel can use the memory for
483	  pagecache and when a subsystem requests for contiguous area, the
484	  allocated pages are migrated away to serve the contiguous request.
485
486	  If unsure, say "n".
487
488config CMA_DEBUG
489	bool "CMA debug messages (DEVELOPMENT)"
490	depends on DEBUG_KERNEL && CMA
491	help
492	  Turns on debug messages in CMA.  This produces KERN_DEBUG
493	  messages for every CMA call as well as various messages while
494	  processing calls such as dma_alloc_from_contiguous().
495	  This option does not affect warning and error messages.
496
497config CMA_DEBUGFS
498	bool "CMA debugfs interface"
499	depends on CMA && DEBUG_FS
500	help
501	  Turns on the DebugFS interface for CMA.
502
503config CMA_SYSFS
504	bool "CMA information through sysfs interface"
505	depends on CMA && SYSFS
506	help
507	  This option exposes some sysfs attributes to get information
508	  from CMA.
509
510config CMA_AREAS
511	int "Maximum count of the CMA areas"
512	depends on CMA
513	default 19 if NUMA
514	default 7
515	help
516	  CMA allows to create CMA areas for particular purpose, mainly,
517	  used as device private area. This parameter sets the maximum
518	  number of CMA area in the system.
519
520	  If unsure, leave the default value "7" in UMA and "19" in NUMA.
521
522config MEM_SOFT_DIRTY
523	bool "Track memory changes"
524	depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
525	select PROC_PAGE_MONITOR
526	help
527	  This option enables memory changes tracking by introducing a
528	  soft-dirty bit on pte-s. This bit it set when someone writes
529	  into a page just as regular dirty bit, but unlike the latter
530	  it can be cleared by hands.
531
532	  See Documentation/admin-guide/mm/soft-dirty.rst for more details.
533
534config ZSWAP
535	bool "Compressed cache for swap pages (EXPERIMENTAL)"
536	depends on FRONTSWAP && CRYPTO=y
537	select ZPOOL
538	help
539	  A lightweight compressed cache for swap pages.  It takes
540	  pages that are in the process of being swapped out and attempts to
541	  compress them into a dynamically allocated RAM-based memory pool.
542	  This can result in a significant I/O reduction on swap device and,
543	  in the case where decompressing from RAM is faster that swap device
544	  reads, can also improve workload performance.
545
546	  This is marked experimental because it is a new feature (as of
547	  v3.11) that interacts heavily with memory reclaim.  While these
548	  interactions don't cause any known issues on simple memory setups,
549	  they have not be fully explored on the large set of potential
550	  configurations and workloads that exist.
551
552choice
553	prompt "Compressed cache for swap pages default compressor"
554	depends on ZSWAP
555	default ZSWAP_COMPRESSOR_DEFAULT_LZO
556	help
557	  Selects the default compression algorithm for the compressed cache
558	  for swap pages.
559
560	  For an overview what kind of performance can be expected from
561	  a particular compression algorithm please refer to the benchmarks
562	  available at the following LWN page:
563	  https://lwn.net/Articles/751795/
564
565	  If in doubt, select 'LZO'.
566
567	  The selection made here can be overridden by using the kernel
568	  command line 'zswap.compressor=' option.
569
570config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
571	bool "Deflate"
572	select CRYPTO_DEFLATE
573	help
574	  Use the Deflate algorithm as the default compression algorithm.
575
576config ZSWAP_COMPRESSOR_DEFAULT_LZO
577	bool "LZO"
578	select CRYPTO_LZO
579	help
580	  Use the LZO algorithm as the default compression algorithm.
581
582config ZSWAP_COMPRESSOR_DEFAULT_842
583	bool "842"
584	select CRYPTO_842
585	help
586	  Use the 842 algorithm as the default compression algorithm.
587
588config ZSWAP_COMPRESSOR_DEFAULT_LZ4
589	bool "LZ4"
590	select CRYPTO_LZ4
591	help
592	  Use the LZ4 algorithm as the default compression algorithm.
593
594config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
595	bool "LZ4HC"
596	select CRYPTO_LZ4HC
597	help
598	  Use the LZ4HC algorithm as the default compression algorithm.
599
600config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
601	bool "zstd"
602	select CRYPTO_ZSTD
603	help
604	  Use the zstd algorithm as the default compression algorithm.
605endchoice
606
607config ZSWAP_COMPRESSOR_DEFAULT
608       string
609       depends on ZSWAP
610       default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
611       default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO
612       default "842" if ZSWAP_COMPRESSOR_DEFAULT_842
613       default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4
614       default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
615       default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
616       default ""
617
618choice
619	prompt "Compressed cache for swap pages default allocator"
620	depends on ZSWAP
621	default ZSWAP_ZPOOL_DEFAULT_ZBUD
622	help
623	  Selects the default allocator for the compressed cache for
624	  swap pages.
625	  The default is 'zbud' for compatibility, however please do
626	  read the description of each of the allocators below before
627	  making a right choice.
628
629	  The selection made here can be overridden by using the kernel
630	  command line 'zswap.zpool=' option.
631
632config ZSWAP_ZPOOL_DEFAULT_ZBUD
633	bool "zbud"
634	select ZBUD
635	help
636	  Use the zbud allocator as the default allocator.
637
638config ZSWAP_ZPOOL_DEFAULT_Z3FOLD
639	bool "z3fold"
640	select Z3FOLD
641	help
642	  Use the z3fold allocator as the default allocator.
643
644config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
645	bool "zsmalloc"
646	select ZSMALLOC
647	help
648	  Use the zsmalloc allocator as the default allocator.
649endchoice
650
651config ZSWAP_ZPOOL_DEFAULT
652       string
653       depends on ZSWAP
654       default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
655       default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD
656       default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
657       default ""
658
659config ZSWAP_DEFAULT_ON
660	bool "Enable the compressed cache for swap pages by default"
661	depends on ZSWAP
662	help
663	  If selected, the compressed cache for swap pages will be enabled
664	  at boot, otherwise it will be disabled.
665
666	  The selection made here can be overridden by using the kernel
667	  command line 'zswap.enabled=' option.
668
669config ZPOOL
670	tristate "Common API for compressed memory storage"
671	help
672	  Compressed memory storage API.  This allows using either zbud or
673	  zsmalloc.
674
675config ZBUD
676	tristate "Low (Up to 2x) density storage for compressed pages"
677	depends on ZPOOL
678	help
679	  A special purpose allocator for storing compressed pages.
680	  It is designed to store up to two compressed pages per physical
681	  page.  While this design limits storage density, it has simple and
682	  deterministic reclaim properties that make it preferable to a higher
683	  density approach when reclaim will be used.
684
685config Z3FOLD
686	tristate "Up to 3x density storage for compressed pages"
687	depends on ZPOOL
688	help
689	  A special purpose allocator for storing compressed pages.
690	  It is designed to store up to three compressed pages per physical
691	  page. It is a ZBUD derivative so the simplicity and determinism are
692	  still there.
693
694config ZSMALLOC
695	tristate "Memory allocator for compressed pages"
696	depends on MMU
697	help
698	  zsmalloc is a slab-based memory allocator designed to store
699	  compressed RAM pages.  zsmalloc uses virtual memory mapping
700	  in order to reduce fragmentation.  However, this results in a
701	  non-standard allocator interface where a handle, not a pointer, is
702	  returned by an alloc().  This handle must be mapped in order to
703	  access the allocated space.
704
705config ZSMALLOC_STAT
706	bool "Export zsmalloc statistics"
707	depends on ZSMALLOC
708	select DEBUG_FS
709	help
710	  This option enables code in the zsmalloc to collect various
711	  statistics about what's happening in zsmalloc and exports that
712	  information to userspace via debugfs.
713	  If unsure, say N.
714
715config GENERIC_EARLY_IOREMAP
716	bool
717
718config STACK_MAX_DEFAULT_SIZE_MB
719	int "Default maximum user stack size for 32-bit processes (MB)"
720	default 100
721	range 8 2048
722	depends on STACK_GROWSUP && (!64BIT || COMPAT)
723	help
724	  This is the maximum stack size in Megabytes in the VM layout of 32-bit
725	  user processes when the stack grows upwards (currently only on parisc
726	  arch) when the RLIMIT_STACK hard limit is unlimited.
727
728	  A sane initial value is 100 MB.
729
730config DEFERRED_STRUCT_PAGE_INIT
731	bool "Defer initialisation of struct pages to kthreads"
732	depends on SPARSEMEM
733	depends on !NEED_PER_CPU_KM
734	depends on 64BIT
735	select PADATA
736	help
737	  Ordinarily all struct pages are initialised during early boot in a
738	  single thread. On very large machines this can take a considerable
739	  amount of time. If this option is set, large machines will bring up
740	  a subset of memmap at boot and then initialise the rest in parallel.
741	  This has a potential performance impact on tasks running early in the
742	  lifetime of the system until these kthreads finish the
743	  initialisation.
744
745config PAGE_IDLE_FLAG
746	bool
747	select PAGE_EXTENSION if !64BIT
748	help
749	  This adds PG_idle and PG_young flags to 'struct page'.  PTE Accessed
750	  bit writers can set the state of the bit in the flags so that PTE
751	  Accessed bit readers may avoid disturbance.
752
753config IDLE_PAGE_TRACKING
754	bool "Enable idle page tracking"
755	depends on SYSFS && MMU
756	select PAGE_IDLE_FLAG
757	help
758	  This feature allows to estimate the amount of user pages that have
759	  not been touched during a given period of time. This information can
760	  be useful to tune memory cgroup limits and/or for job placement
761	  within a compute cluster.
762
763	  See Documentation/admin-guide/mm/idle_page_tracking.rst for
764	  more details.
765
766config ARCH_HAS_CACHE_LINE_SIZE
767	bool
768
769config ARCH_HAS_PTE_DEVMAP
770	bool
771
772config ARCH_HAS_ZONE_DMA_SET
773	bool
774
775config ZONE_DMA
776	bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET
777	default y if ARM64 || X86
778
779config ZONE_DMA32
780	bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET
781	depends on !X86_32
782	default y if ARM64
783
784config ZONE_DEVICE
785	bool "Device memory (pmem, HMM, etc...) hotplug support"
786	depends on MEMORY_HOTPLUG
787	depends on MEMORY_HOTREMOVE
788	depends on SPARSEMEM_VMEMMAP
789	depends on ARCH_HAS_PTE_DEVMAP
790	select XARRAY_MULTI
791
792	help
793	  Device memory hotplug support allows for establishing pmem,
794	  or other device driver discovered memory regions, in the
795	  memmap. This allows pfn_to_page() lookups of otherwise
796	  "device-physical" addresses which is needed for using a DAX
797	  mapping in an O_DIRECT operation, among other things.
798
799	  If FS_DAX is enabled, then say Y.
800
801config DEV_PAGEMAP_OPS
802	bool
803
804#
805# Helpers to mirror range of the CPU page tables of a process into device page
806# tables.
807#
808config HMM_MIRROR
809	bool
810	depends on MMU
811
812config DEVICE_PRIVATE
813	bool "Unaddressable device memory (GPU memory, ...)"
814	depends on ZONE_DEVICE
815	select DEV_PAGEMAP_OPS
816
817	help
818	  Allows creation of struct pages to represent unaddressable device
819	  memory; i.e., memory that is only accessible from the device (or
820	  group of devices). You likely also want to select HMM_MIRROR.
821
822config VMAP_PFN
823	bool
824
825config ARCH_USES_HIGH_VMA_FLAGS
826	bool
827config ARCH_HAS_PKEYS
828	bool
829
830config PERCPU_STATS
831	bool "Collect percpu memory statistics"
832	help
833	  This feature collects and exposes statistics via debugfs. The
834	  information includes global and per chunk statistics, which can
835	  be used to help understand percpu memory usage.
836
837config GUP_TEST
838	bool "Enable infrastructure for get_user_pages()-related unit tests"
839	depends on DEBUG_FS
840	help
841	  Provides /sys/kernel/debug/gup_test, which in turn provides a way
842	  to make ioctl calls that can launch kernel-based unit tests for
843	  the get_user_pages*() and pin_user_pages*() family of API calls.
844
845	  These tests include benchmark testing of the _fast variants of
846	  get_user_pages*() and pin_user_pages*(), as well as smoke tests of
847	  the non-_fast variants.
848
849	  There is also a sub-test that allows running dump_page() on any
850	  of up to eight pages (selected by command line args) within the
851	  range of user-space addresses. These pages are either pinned via
852	  pin_user_pages*(), or pinned via get_user_pages*(), as specified
853	  by other command line arguments.
854
855	  See tools/testing/selftests/vm/gup_test.c
856
857comment "GUP_TEST needs to have DEBUG_FS enabled"
858	depends on !GUP_TEST && !DEBUG_FS
859
860config GUP_GET_PTE_LOW_HIGH
861	bool
862
863config READ_ONLY_THP_FOR_FS
864	bool "Read-only THP for filesystems (EXPERIMENTAL)"
865	depends on TRANSPARENT_HUGEPAGE && SHMEM
866
867	help
868	  Allow khugepaged to put read-only file-backed pages in THP.
869
870	  This is marked experimental because it is a new feature. Write
871	  support of file THPs will be developed in the next few release
872	  cycles.
873
874config ARCH_HAS_PTE_SPECIAL
875	bool
876
877#
878# Some architectures require a special hugepage directory format that is
879# required to support multiple hugepage sizes. For example a4fe3ce76
880# "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
881# introduced it on powerpc.  This allows for a more flexible hugepage
882# pagetable layouts.
883#
884config ARCH_HAS_HUGEPD
885	bool
886
887config MAPPING_DIRTY_HELPERS
888        bool
889
890config KMAP_LOCAL
891	bool
892
893config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
894	bool
895
896# struct io_mapping based helper.  Selected by drivers that need them
897config IO_MAPPING
898	bool
899
900config SECRETMEM
901	def_bool ARCH_HAS_SET_DIRECT_MAP && !EMBEDDED
902
903source "mm/damon/Kconfig"
904
905endmenu
906