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TOMOYO Linux Cross Reference
Linux/mm/Kconfig

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Diff markup

Differences between /mm/Kconfig (Version linux-6.12-rc7) and /mm/Kconfig (Version linux-5.16.20)


  1 # SPDX-License-Identifier: GPL-2.0-only             1 # SPDX-License-Identifier: GPL-2.0-only
  2                                                     2 
  3 menu "Memory Management options"                    3 menu "Memory Management options"
  4                                                     4 
  5 #                                              << 
  6 # For some reason microblaze and nios2 hard co << 
  7 # add proper SWAP support to them, in which ca << 
  8 #                                              << 
  9 config ARCH_NO_SWAP                            << 
 10         bool                                   << 
 11                                                << 
 12 config ZPOOL                                   << 
 13         bool                                   << 
 14                                                << 
 15 menuconfig SWAP                                << 
 16         bool "Support for paging of anonymous  << 
 17         depends on MMU && BLOCK && !ARCH_NO_SW << 
 18         default y                              << 
 19         help                                   << 
 20           This option allows you to choose whe << 
 21           for so called swap devices or swap f << 
 22           used to provide more virtual memory  << 
 23           in your computer.  If unsure say Y.  << 
 24                                                << 
 25 config ZSWAP                                   << 
 26         bool "Compressed cache for swap pages" << 
 27         depends on SWAP                        << 
 28         select CRYPTO                          << 
 29         select ZPOOL                           << 
 30         help                                   << 
 31           A lightweight compressed cache for s << 
 32           pages that are in the process of bei << 
 33           compress them into a dynamically all << 
 34           This can result in a significant I/O << 
 35           in the case where decompressing from << 
 36           reads, can also improve workload per << 
 37                                                << 
 38 config ZSWAP_DEFAULT_ON                        << 
 39         bool "Enable the compressed cache for  << 
 40         depends on ZSWAP                       << 
 41         help                                   << 
 42           If selected, the compressed cache fo << 
 43           at boot, otherwise it will be disabl << 
 44                                                << 
 45           The selection made here can be overr << 
 46           command line 'zswap.enabled=' option << 
 47                                                << 
 48 config ZSWAP_SHRINKER_DEFAULT_ON               << 
 49         bool "Shrink the zswap pool on memory  << 
 50         depends on ZSWAP                       << 
 51         default n                              << 
 52         help                                   << 
 53           If selected, the zswap shrinker will << 
 54           stored in the zswap pool will become << 
 55           written back to the backing swap dev << 
 56                                                << 
 57           This means that zswap writeback coul << 
 58           not yet full, or the cgroup zswap li << 
 59           reducing the chance that cold pages  << 
 60           and consume memory indefinitely.     << 
 61                                                << 
 62 choice                                         << 
 63         prompt "Default compressor"            << 
 64         depends on ZSWAP                       << 
 65         default ZSWAP_COMPRESSOR_DEFAULT_LZO   << 
 66         help                                   << 
 67           Selects the default compression algo << 
 68           for swap pages.                      << 
 69                                                << 
 70           For an overview what kind of perform << 
 71           a particular compression algorithm p << 
 72           available at the following LWN page: << 
 73           https://lwn.net/Articles/751795/     << 
 74                                                << 
 75           If in doubt, select 'LZO'.           << 
 76                                                << 
 77           The selection made here can be overr << 
 78           command line 'zswap.compressor=' opt << 
 79                                                << 
 80 config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE        << 
 81         bool "Deflate"                         << 
 82         select CRYPTO_DEFLATE                  << 
 83         help                                   << 
 84           Use the Deflate algorithm as the def << 
 85                                                << 
 86 config ZSWAP_COMPRESSOR_DEFAULT_LZO            << 
 87         bool "LZO"                             << 
 88         select CRYPTO_LZO                      << 
 89         help                                   << 
 90           Use the LZO algorithm as the default << 
 91                                                << 
 92 config ZSWAP_COMPRESSOR_DEFAULT_842            << 
 93         bool "842"                             << 
 94         select CRYPTO_842                      << 
 95         help                                   << 
 96           Use the 842 algorithm as the default << 
 97                                                << 
 98 config ZSWAP_COMPRESSOR_DEFAULT_LZ4            << 
 99         bool "LZ4"                             << 
100         select CRYPTO_LZ4                      << 
101         help                                   << 
102           Use the LZ4 algorithm as the default << 
103                                                << 
104 config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC          << 
105         bool "LZ4HC"                           << 
106         select CRYPTO_LZ4HC                    << 
107         help                                   << 
108           Use the LZ4HC algorithm as the defau << 
109                                                << 
110 config ZSWAP_COMPRESSOR_DEFAULT_ZSTD           << 
111         bool "zstd"                            << 
112         select CRYPTO_ZSTD                     << 
113         help                                   << 
114           Use the zstd algorithm as the defaul << 
115 endchoice                                      << 
116                                                << 
117 config ZSWAP_COMPRESSOR_DEFAULT                << 
118        string                                  << 
119        depends on ZSWAP                        << 
120        default "deflate" if ZSWAP_COMPRESSOR_D << 
121        default "lzo" if ZSWAP_COMPRESSOR_DEFAU << 
122        default "842" if ZSWAP_COMPRESSOR_DEFAU << 
123        default "lz4" if ZSWAP_COMPRESSOR_DEFAU << 
124        default "lz4hc" if ZSWAP_COMPRESSOR_DEF << 
125        default "zstd" if ZSWAP_COMPRESSOR_DEFA << 
126        default ""                              << 
127                                                << 
128 choice                                         << 
129         prompt "Default allocator"             << 
130         depends on ZSWAP                       << 
131         default ZSWAP_ZPOOL_DEFAULT_ZSMALLOC i << 
132         default ZSWAP_ZPOOL_DEFAULT_ZBUD       << 
133         help                                   << 
134           Selects the default allocator for th << 
135           swap pages.                          << 
136           The default is 'zbud' for compatibil << 
137           read the description of each of the  << 
138           making a right choice.               << 
139                                                << 
140           The selection made here can be overr << 
141           command line 'zswap.zpool=' option.  << 
142                                                << 
143 config ZSWAP_ZPOOL_DEFAULT_ZBUD                << 
144         bool "zbud"                            << 
145         select ZBUD                            << 
146         help                                   << 
147           Use the zbud allocator as the defaul << 
148                                                << 
149 config ZSWAP_ZPOOL_DEFAULT_Z3FOLD_DEPRECATED   << 
150         bool "z3foldi (DEPRECATED)"            << 
151         select Z3FOLD_DEPRECATED               << 
152         help                                   << 
153           Use the z3fold allocator as the defa << 
154                                                << 
155           Deprecated and scheduled for removal << 
156           see CONFIG_Z3FOLD_DEPRECATED.        << 
157                                                << 
158 config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC            << 
159         bool "zsmalloc"                        << 
160         select ZSMALLOC                        << 
161         help                                   << 
162           Use the zsmalloc allocator as the de << 
163 endchoice                                      << 
164                                                << 
165 config ZSWAP_ZPOOL_DEFAULT                     << 
166        string                                  << 
167        depends on ZSWAP                        << 
168        default "zbud" if ZSWAP_ZPOOL_DEFAULT_Z << 
169        default "z3fold" if ZSWAP_ZPOOL_DEFAULT << 
170        default "zsmalloc" if ZSWAP_ZPOOL_DEFAU << 
171        default ""                              << 
172                                                << 
173 config ZBUD                                    << 
174         tristate "2:1 compression allocator (z << 
175         depends on ZSWAP                       << 
176         help                                   << 
177           A special purpose allocator for stor << 
178           It is designed to store up to two co << 
179           page.  While this design limits stor << 
180           deterministic reclaim properties tha << 
181           density approach when reclaim will b << 
182                                                << 
183 config Z3FOLD_DEPRECATED                       << 
184         tristate "3:1 compression allocator (z << 
185         depends on ZSWAP                       << 
186         help                                   << 
187           Deprecated and scheduled for removal << 
188           a good reason for using Z3FOLD over  << 
189           linux-mm@kvack.org and the zswap mai << 
190                                                << 
191           A special purpose allocator for stor << 
192           It is designed to store up to three  << 
193           page. It is a ZBUD derivative so the << 
194           still there.                         << 
195                                                << 
196 config Z3FOLD                                  << 
197         tristate                               << 
198         default y if Z3FOLD_DEPRECATED=y       << 
199         default m if Z3FOLD_DEPRECATED=m       << 
200         depends on Z3FOLD_DEPRECATED           << 
201                                                << 
202 config ZSMALLOC                                << 
203         tristate                               << 
204         prompt "N:1 compression allocator (zsm << 
205         depends on MMU                         << 
206         help                                   << 
207           zsmalloc is a slab-based memory allo << 
208           pages of various compression levels  << 
209           the highest storage density with the << 
210                                                << 
211 config ZSMALLOC_STAT                           << 
212         bool "Export zsmalloc statistics"      << 
213         depends on ZSMALLOC                    << 
214         select DEBUG_FS                        << 
215         help                                   << 
216           This option enables code in the zsma << 
217           statistics about what's happening in << 
218           information to userspace via debugfs << 
219           If unsure, say N.                    << 
220                                                << 
221 config ZSMALLOC_CHAIN_SIZE                     << 
222         int "Maximum number of physical pages  << 
223         default 8                              << 
224         range 4 16                             << 
225         depends on ZSMALLOC                    << 
226         help                                   << 
227           This option sets the upper limit on  << 
228           that a zmalloc page (zspage) can con << 
229           chain size is calculated for each si << 
230           initialization of the pool.          << 
231                                                << 
232           Changing this option can alter the c << 
233           such as the number of pages per zspa << 
234           per zspage. This can also result in  << 
235           the pool, as zsmalloc merges size cl << 
236           characteristics.                     << 
237                                                << 
238           For more information, see zsmalloc d << 
239                                                << 
240 menu "Slab allocator options"                  << 
241                                                << 
242 config SLUB                                    << 
243         def_bool y                             << 
244                                                << 
245 config SLUB_TINY                               << 
246         bool "Configure for minimal memory foo << 
247         depends on EXPERT                      << 
248         select SLAB_MERGE_DEFAULT              << 
249         help                                   << 
250            Configures the slab allocator in a  << 
251            footprint, sacrificing scalability, << 
252            This is intended only for the small << 
253            SLOB allocator and is not recommend << 
254            16MB RAM.                           << 
255                                                << 
256            If unsure, say N.                   << 
257                                                << 
258 config SLAB_MERGE_DEFAULT                      << 
259         bool "Allow slab caches to be merged"  << 
260         default y                              << 
261         help                                   << 
262           For reduced kernel memory fragmentat << 
263           merged when they share the same size << 
264           This carries a risk of kernel heap o << 
265           overwrite objects from merged caches << 
266           cache layout), which makes such heap << 
267           by attackers. By keeping caches unme << 
268           can usually only damage objects in t << 
269           merging at runtime, "slab_nomerge" c << 
270           command line.                        << 
271                                                << 
272 config SLAB_FREELIST_RANDOM                    << 
273         bool "Randomize slab freelist"         << 
274         depends on !SLUB_TINY                  << 
275         help                                   << 
276           Randomizes the freelist order used o << 
277           security feature reduces the predict << 
278           allocator against heap overflows.    << 
279                                                << 
280 config SLAB_FREELIST_HARDENED                  << 
281         bool "Harden slab freelist metadata"   << 
282         depends on !SLUB_TINY                  << 
283         help                                   << 
284           Many kernel heap attacks try to targ << 
285           other infrastructure. This options m << 
286           sacrifices to harden the kernel slab << 
287           freelist exploit methods.            << 
288                                                << 
289 config SLAB_BUCKETS                            << 
290         bool "Support allocation from separate << 
291         depends on !SLUB_TINY                  << 
292         default SLAB_FREELIST_HARDENED         << 
293         help                                   << 
294           Kernel heap attacks frequently depen << 
295           specifically-sized allocations with  << 
296           that will be allocated into the same << 
297           target object. To avoid sharing thes << 
298           provide an explicitly separated set  << 
299           user-controlled allocations. This ma << 
300           memory fragmentation, though in prac << 
301           of extra pages since the bulk of use << 
302           are relatively long-lived.           << 
303                                                << 
304           If unsure, say Y.                    << 
305                                                << 
306 config SLUB_STATS                              << 
307         default n                              << 
308         bool "Enable performance statistics"   << 
309         depends on SYSFS && !SLUB_TINY         << 
310         help                                   << 
311           The statistics are useful to debug s << 
312           order find ways to optimize the allo << 
313           enabled for production use since kee << 
314           the allocator by a few percentage po << 
315           supports the determination of the mo << 
316           out which slabs are relevant to a pa << 
317           Try running: slabinfo -DA            << 
318                                                << 
319 config SLUB_CPU_PARTIAL                        << 
320         default y                              << 
321         depends on SMP && !SLUB_TINY           << 
322         bool "Enable per cpu partial caches"   << 
323         help                                   << 
324           Per cpu partial caches accelerate ob << 
325           that is local to a processor at the  << 
326           in the latency of the free. On overf << 
327           which requires the taking of locks t << 
328           Typically one would choose no for a  << 
329                                                << 
330 config RANDOM_KMALLOC_CACHES                   << 
331         default n                              << 
332         depends on !SLUB_TINY                  << 
333         bool "Randomize slab caches for normal << 
334         help                                   << 
335           A hardening feature that creates mul << 
336           normal kmalloc allocation and makes  << 
337           on code address, which makes the att << 
338           vulnerable memory objects on the hea << 
339           memory vulnerabilities.              << 
340                                                << 
341           Currently the number of copies is se << 
342           that effectively diverges the memory << 
343           subsystems or modules into different << 
344           limited degree of memory and CPU ove << 
345           system workload.                     << 
346                                                << 
347 endmenu # Slab allocator options               << 
348                                                << 
349 config SHUFFLE_PAGE_ALLOCATOR                  << 
350         bool "Page allocator randomization"    << 
351         default SLAB_FREELIST_RANDOM && ACPI_N << 
352         help                                   << 
353           Randomization of the page allocator  << 
354           utilization of a direct-mapped memor << 
355           5.2.27 Heterogeneous Memory Attribut << 
356           6.2a specification for an example of << 
357           the presence of a memory-side-cache. << 
358           security benefits as it reduces the  << 
359           allocations to compliment SLAB_FREEL << 
360           default granularity of shuffling on  << 
361           order of pages is selected based on  << 
362           on x86.                              << 
363                                                << 
364           While the randomization improves cac << 
365           negatively impact workloads on platf << 
366           this reason, by default, the randomi << 
367           if SHUFFLE_PAGE_ALLOCATOR=y. The ran << 
368           with the 'page_alloc.shuffle' kernel << 
369                                                << 
370           Say Y if unsure.                     << 
371                                                << 
372 config COMPAT_BRK                              << 
373         bool "Disable heap randomization"      << 
374         default y                              << 
375         help                                   << 
376           Randomizing heap placement makes hea << 
377           also breaks ancient binaries (includ << 
378           This option changes the bootup defau << 
379           disabled, and can be overridden at r << 
380           /proc/sys/kernel/randomize_va_space  << 
381                                                << 
382           On non-ancient distros (post-2000 on << 
383                                                << 
384 config MMAP_ALLOW_UNINITIALIZED                << 
385         bool "Allow mmapped anonymous memory t << 
386         depends on EXPERT && !MMU              << 
387         default n                              << 
388         help                                   << 
389           Normally, and according to the Linux << 
390           from mmap() has its contents cleared << 
391           userspace.  Enabling this config opt << 
392           mmap() skip that if it is given an M << 
393           providing a huge performance boost.  << 
394           then the flag will be ignored.       << 
395                                                << 
396           This is taken advantage of by uClibc << 
397           ELF-FDPIC binfmt's brk and stack all << 
398                                                << 
399           Because of the obvious security issu << 
400           enabled on embedded devices where yo << 
401           userspace.  Since that isn't general << 
402           it is normally safe to say Y here.   << 
403                                                << 
404           See Documentation/admin-guide/mm/nom << 
405                                                << 
406 config SELECT_MEMORY_MODEL                          5 config SELECT_MEMORY_MODEL
407         def_bool y                                  6         def_bool y
408         depends on ARCH_SELECT_MEMORY_MODEL         7         depends on ARCH_SELECT_MEMORY_MODEL
409                                                     8 
410 choice                                              9 choice
411         prompt "Memory model"                      10         prompt "Memory model"
412         depends on SELECT_MEMORY_MODEL             11         depends on SELECT_MEMORY_MODEL
413         default SPARSEMEM_MANUAL if ARCH_SPARS     12         default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
414         default FLATMEM_MANUAL                     13         default FLATMEM_MANUAL
415         help                                       14         help
416           This option allows you to change som     15           This option allows you to change some of the ways that
417           Linux manages its memory internally.     16           Linux manages its memory internally. Most users will
418           only have one option here selected b     17           only have one option here selected by the architecture
419           configuration. This is normal.           18           configuration. This is normal.
420                                                    19 
421 config FLATMEM_MANUAL                              20 config FLATMEM_MANUAL
422         bool "Flat Memory"                         21         bool "Flat Memory"
423         depends on !ARCH_SPARSEMEM_ENABLE || A     22         depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
424         help                                       23         help
425           This option is best suited for non-N     24           This option is best suited for non-NUMA systems with
426           flat address space. The FLATMEM is t     25           flat address space. The FLATMEM is the most efficient
427           system in terms of performance and r     26           system in terms of performance and resource consumption
428           and it is the best option for smalle     27           and it is the best option for smaller systems.
429                                                    28 
430           For systems that have holes in their     29           For systems that have holes in their physical address
431           spaces and for features like NUMA an     30           spaces and for features like NUMA and memory hotplug,
432           choose "Sparse Memory".                  31           choose "Sparse Memory".
433                                                    32 
434           If unsure, choose this option (Flat      33           If unsure, choose this option (Flat Memory) over any other.
435                                                    34 
436 config SPARSEMEM_MANUAL                            35 config SPARSEMEM_MANUAL
437         bool "Sparse Memory"                       36         bool "Sparse Memory"
438         depends on ARCH_SPARSEMEM_ENABLE           37         depends on ARCH_SPARSEMEM_ENABLE
439         help                                       38         help
440           This will be the only option for som     39           This will be the only option for some systems, including
441           memory hot-plug systems.  This is no     40           memory hot-plug systems.  This is normal.
442                                                    41 
443           This option provides efficient suppo     42           This option provides efficient support for systems with
444           holes is their physical address spac     43           holes is their physical address space and allows memory
445           hot-plug and hot-remove.                 44           hot-plug and hot-remove.
446                                                    45 
447           If unsure, choose "Flat Memory" over     46           If unsure, choose "Flat Memory" over this option.
448                                                    47 
449 endchoice                                          48 endchoice
450                                                    49 
451 config SPARSEMEM                                   50 config SPARSEMEM
452         def_bool y                                 51         def_bool y
453         depends on (!SELECT_MEMORY_MODEL && AR     52         depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
454                                                    53 
455 config FLATMEM                                     54 config FLATMEM
456         def_bool y                                 55         def_bool y
457         depends on !SPARSEMEM || FLATMEM_MANUA     56         depends on !SPARSEMEM || FLATMEM_MANUAL
458                                                    57 
459 #                                                  58 #
460 # SPARSEMEM_EXTREME (which is the default) doe     59 # SPARSEMEM_EXTREME (which is the default) does some bootmem
461 # allocations when sparse_init() is called.  I     60 # allocations when sparse_init() is called.  If this cannot
462 # be done on your architecture, select this op     61 # be done on your architecture, select this option.  However,
463 # statically allocating the mem_section[] arra     62 # statically allocating the mem_section[] array can potentially
464 # consume vast quantities of .bss, so be caref     63 # consume vast quantities of .bss, so be careful.
465 #                                                  64 #
466 # This option will also potentially produce sm     65 # This option will also potentially produce smaller runtime code
467 # with gcc 3.4 and later.                          66 # with gcc 3.4 and later.
468 #                                                  67 #
469 config SPARSEMEM_STATIC                            68 config SPARSEMEM_STATIC
470         bool                                       69         bool
471                                                    70 
472 #                                                  71 #
473 # Architecture platforms which require a two l     72 # Architecture platforms which require a two level mem_section in SPARSEMEM
474 # must select this option. This is usually for     73 # must select this option. This is usually for architecture platforms with
475 # an extremely sparse physical address space.      74 # an extremely sparse physical address space.
476 #                                                  75 #
477 config SPARSEMEM_EXTREME                           76 config SPARSEMEM_EXTREME
478         def_bool y                                 77         def_bool y
479         depends on SPARSEMEM && !SPARSEMEM_STA     78         depends on SPARSEMEM && !SPARSEMEM_STATIC
480                                                    79 
481 config SPARSEMEM_VMEMMAP_ENABLE                    80 config SPARSEMEM_VMEMMAP_ENABLE
482         bool                                       81         bool
483                                                    82 
484 config SPARSEMEM_VMEMMAP                           83 config SPARSEMEM_VMEMMAP
485         bool "Sparse Memory virtual memmap"        84         bool "Sparse Memory virtual memmap"
486         depends on SPARSEMEM && SPARSEMEM_VMEM     85         depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
487         default y                                  86         default y
488         help                                       87         help
489           SPARSEMEM_VMEMMAP uses a virtually m     88           SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
490           pfn_to_page and page_to_pfn operatio     89           pfn_to_page and page_to_pfn operations.  This is the most
491           efficient option when sufficient ker     90           efficient option when sufficient kernel resources are available.
492 #                                              << 
493 # Select this config option from the architect << 
494 # to enable the feature of HugeTLB/dev_dax vme << 
495 #                                              << 
496 config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP          << 
497         bool                                   << 
498                                                << 
499 config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP      << 
500         bool                                   << 
501                                                    91 
502 config HAVE_MEMBLOCK_PHYS_MAP                      92 config HAVE_MEMBLOCK_PHYS_MAP
503         bool                                       93         bool
504                                                    94 
505 config HAVE_GUP_FAST                           !!  95 config HAVE_FAST_GUP
506         depends on MMU                             96         depends on MMU
507         bool                                       97         bool
508                                                    98 
509 # Don't discard allocated memory used to track     99 # Don't discard allocated memory used to track "memory" and "reserved" memblocks
510 # after early boot, so it can still be used to    100 # after early boot, so it can still be used to test for validity of memory.
511 # Also, memblocks are updated with memory hot(    101 # Also, memblocks are updated with memory hot(un)plug.
512 config ARCH_KEEP_MEMBLOCK                         102 config ARCH_KEEP_MEMBLOCK
513         bool                                      103         bool
514                                                   104 
515 # Keep arch NUMA mapping infrastructure post-i    105 # Keep arch NUMA mapping infrastructure post-init.
516 config NUMA_KEEP_MEMINFO                          106 config NUMA_KEEP_MEMINFO
517         bool                                      107         bool
518                                                   108 
519 config MEMORY_ISOLATION                           109 config MEMORY_ISOLATION
520         bool                                      110         bool
521                                                   111 
522 # IORESOURCE_SYSTEM_RAM regions in the kernel     112 # IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
523 # IORESOURCE_EXCLUSIVE cannot be mapped to use    113 # IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
524 # /dev/mem.                                       114 # /dev/mem.
525 config EXCLUSIVE_SYSTEM_RAM                       115 config EXCLUSIVE_SYSTEM_RAM
526         def_bool y                                116         def_bool y
527         depends on !DEVMEM || STRICT_DEVMEM       117         depends on !DEVMEM || STRICT_DEVMEM
528                                                   118 
529 #                                                 119 #
530 # Only be set on architectures that have compl    120 # Only be set on architectures that have completely implemented memory hotplug
531 # feature. If you are not sure, don't touch it    121 # feature. If you are not sure, don't touch it.
532 #                                                 122 #
533 config HAVE_BOOTMEM_INFO_NODE                     123 config HAVE_BOOTMEM_INFO_NODE
534         def_bool n                                124         def_bool n
535                                                   125 
536 config ARCH_ENABLE_MEMORY_HOTPLUG                 126 config ARCH_ENABLE_MEMORY_HOTPLUG
537         bool                                      127         bool
538                                                   128 
539 config ARCH_ENABLE_MEMORY_HOTREMOVE            << 
540         bool                                   << 
541                                                << 
542 # eventually, we can have this option just 'se    129 # eventually, we can have this option just 'select SPARSEMEM'
543 menuconfig MEMORY_HOTPLUG                      !! 130 config MEMORY_HOTPLUG
544         bool "Memory hotplug"                  !! 131         bool "Allow for memory hot-add"
545         select MEMORY_ISOLATION                   132         select MEMORY_ISOLATION
546         depends on SPARSEMEM                      133         depends on SPARSEMEM
547         depends on ARCH_ENABLE_MEMORY_HOTPLUG     134         depends on ARCH_ENABLE_MEMORY_HOTPLUG
548         depends on 64BIT                          135         depends on 64BIT
549         select NUMA_KEEP_MEMINFO if NUMA          136         select NUMA_KEEP_MEMINFO if NUMA
550                                                   137 
551 if MEMORY_HOTPLUG                              << 
552                                                << 
553 config MEMORY_HOTPLUG_DEFAULT_ONLINE              138 config MEMORY_HOTPLUG_DEFAULT_ONLINE
554         bool "Online the newly added memory bl    139         bool "Online the newly added memory blocks by default"
555         depends on MEMORY_HOTPLUG                 140         depends on MEMORY_HOTPLUG
556         help                                      141         help
557           This option sets the default policy     142           This option sets the default policy setting for memory hotplug
558           onlining policy (/sys/devices/system    143           onlining policy (/sys/devices/system/memory/auto_online_blocks) which
559           determines what happens to newly add    144           determines what happens to newly added memory regions. Policy setting
560           can always be changed at runtime.       145           can always be changed at runtime.
561           See Documentation/admin-guide/mm/mem    146           See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
562                                                   147 
563           Say Y here if you want all hot-plugg    148           Say Y here if you want all hot-plugged memory blocks to appear in
564           'online' state by default.              149           'online' state by default.
565           Say N here if you want the default p    150           Say N here if you want the default policy to keep all hot-plugged
566           memory blocks in 'offline' state.       151           memory blocks in 'offline' state.
567                                                   152 
                                                   >> 153 config ARCH_ENABLE_MEMORY_HOTREMOVE
                                                   >> 154         bool
                                                   >> 155 
568 config MEMORY_HOTREMOVE                           156 config MEMORY_HOTREMOVE
569         bool "Allow for memory hot remove"        157         bool "Allow for memory hot remove"
570         select HAVE_BOOTMEM_INFO_NODE if (X86_    158         select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
571         depends on MEMORY_HOTPLUG && ARCH_ENAB    159         depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
572         depends on MIGRATION                      160         depends on MIGRATION
573                                                   161 
574 config MHP_MEMMAP_ON_MEMORY                       162 config MHP_MEMMAP_ON_MEMORY
575         def_bool y                                163         def_bool y
576         depends on MEMORY_HOTPLUG && SPARSEMEM    164         depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP
577         depends on ARCH_MHP_MEMMAP_ON_MEMORY_E    165         depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
578                                                   166 
579 endif # MEMORY_HOTPLUG                         << 
580                                                << 
581 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE        << 
582        bool                                    << 
583                                                << 
584 # Heavily threaded applications may benefit fr    167 # Heavily threaded applications may benefit from splitting the mm-wide
585 # page_table_lock, so that faults on different    168 # page_table_lock, so that faults on different parts of the user address
586 # space can be handled with less contention: s    169 # space can be handled with less contention: split it at this NR_CPUS.
587 # Default to 4 for wider testing, though 8 mig    170 # Default to 4 for wider testing, though 8 might be more appropriate.
588 # ARM's adjust_pte (unused if VIPT) depends on    171 # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
589 # PA-RISC 7xxx's spinlock_t would enlarge stru    172 # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
590 # SPARC32 allocates multiple pte tables within    173 # SPARC32 allocates multiple pte tables within a single page, and therefore
591 # a per-page lock leads to problems when multi    174 # a per-page lock leads to problems when multiple tables need to be locked
592 # at the same time (e.g. copy_page_range()).      175 # at the same time (e.g. copy_page_range()).
593 # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock    176 # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
594 #                                                 177 #
595 config SPLIT_PTE_PTLOCKS                       !! 178 config SPLIT_PTLOCK_CPUS
596         def_bool y                             !! 179         int
597         depends on MMU                         !! 180         default "999999" if !MMU
598         depends on SMP                         !! 181         default "999999" if ARM && !CPU_CACHE_VIPT
599         depends on NR_CPUS >= 4                !! 182         default "999999" if PARISC && !PA20
600         depends on !ARM || CPU_CACHE_VIPT      !! 183         default "999999" if SPARC32
601         depends on !PARISC || PA20             !! 184         default "4"
602         depends on !SPARC32                    << 
603                                                   185 
604 config ARCH_ENABLE_SPLIT_PMD_PTLOCK               186 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
605         bool                                      187         bool
606                                                   188 
607 config SPLIT_PMD_PTLOCKS                       << 
608         def_bool y                             << 
609         depends on SPLIT_PTE_PTLOCKS && ARCH_E << 
610                                                << 
611 #                                                 189 #
612 # support for memory balloon                      190 # support for memory balloon
613 config MEMORY_BALLOON                             191 config MEMORY_BALLOON
614         bool                                      192         bool
615                                                   193 
616 #                                                 194 #
617 # support for memory balloon compaction           195 # support for memory balloon compaction
618 config BALLOON_COMPACTION                         196 config BALLOON_COMPACTION
619         bool "Allow for balloon memory compact    197         bool "Allow for balloon memory compaction/migration"
620         default y                              !! 198         def_bool y
621         depends on COMPACTION && MEMORY_BALLOO    199         depends on COMPACTION && MEMORY_BALLOON
622         help                                      200         help
623           Memory fragmentation introduced by b    201           Memory fragmentation introduced by ballooning might reduce
624           significantly the number of 2MB cont    202           significantly the number of 2MB contiguous memory blocks that can be
625           used within a guest, thus imposing p    203           used within a guest, thus imposing performance penalties associated
626           with the reduced number of transpare    204           with the reduced number of transparent huge pages that could be used
627           by the guest workload. Allowing the     205           by the guest workload. Allowing the compaction & migration for memory
628           pages enlisted as being part of memo    206           pages enlisted as being part of memory balloon devices avoids the
629           scenario aforementioned and helps im    207           scenario aforementioned and helps improving memory defragmentation.
630                                                   208 
631 #                                                 209 #
632 # support for memory compaction                   210 # support for memory compaction
633 config COMPACTION                                 211 config COMPACTION
634         bool "Allow for memory compaction"        212         bool "Allow for memory compaction"
635         default y                              !! 213         def_bool y
636         select MIGRATION                          214         select MIGRATION
637         depends on MMU                            215         depends on MMU
638         help                                      216         help
639           Compaction is the only memory manage    217           Compaction is the only memory management component to form
640           high order (larger physically contig    218           high order (larger physically contiguous) memory blocks
641           reliably. The page allocator relies     219           reliably. The page allocator relies on compaction heavily and
642           the lack of the feature can lead to     220           the lack of the feature can lead to unexpected OOM killer
643           invocations for high order memory re    221           invocations for high order memory requests. You shouldn't
644           disable this option unless there rea    222           disable this option unless there really is a strong reason for
645           it and then we would be really inter    223           it and then we would be really interested to hear about that at
646           linux-mm@kvack.org.                     224           linux-mm@kvack.org.
647                                                   225 
648 config COMPACT_UNEVICTABLE_DEFAULT             << 
649         int                                    << 
650         depends on COMPACTION                  << 
651         default 0 if PREEMPT_RT                << 
652         default 1                              << 
653                                                << 
654 #                                                 226 #
655 # support for free page reporting                 227 # support for free page reporting
656 config PAGE_REPORTING                             228 config PAGE_REPORTING
657         bool "Free page reporting"                229         bool "Free page reporting"
                                                   >> 230         def_bool n
658         help                                      231         help
659           Free page reporting allows for the i    232           Free page reporting allows for the incremental acquisition of
660           free pages from the buddy allocator     233           free pages from the buddy allocator for the purpose of reporting
661           those pages to another entity, such     234           those pages to another entity, such as a hypervisor, so that the
662           memory can be freed within the host     235           memory can be freed within the host for other uses.
663                                                   236 
664 #                                                 237 #
665 # support for page migration                      238 # support for page migration
666 #                                                 239 #
667 config MIGRATION                                  240 config MIGRATION
668         bool "Page migration"                     241         bool "Page migration"
669         default y                              !! 242         def_bool y
670         depends on (NUMA || ARCH_ENABLE_MEMORY    243         depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
671         help                                      244         help
672           Allows the migration of the physical    245           Allows the migration of the physical location of pages of processes
673           while the virtual addresses are not     246           while the virtual addresses are not changed. This is useful in
674           two situations. The first is on NUMA    247           two situations. The first is on NUMA systems to put pages nearer
675           to the processors accessing. The sec    248           to the processors accessing. The second is when allocating huge
676           pages as migration can relocate page    249           pages as migration can relocate pages to satisfy a huge page
677           allocation instead of reclaiming.       250           allocation instead of reclaiming.
678                                                   251 
679 config DEVICE_MIGRATION                        << 
680         def_bool MIGRATION && ZONE_DEVICE      << 
681                                                << 
682 config ARCH_ENABLE_HUGEPAGE_MIGRATION             252 config ARCH_ENABLE_HUGEPAGE_MIGRATION
683         bool                                      253         bool
684                                                   254 
685 config ARCH_ENABLE_THP_MIGRATION                  255 config ARCH_ENABLE_THP_MIGRATION
686         bool                                      256         bool
687                                                   257 
688 config HUGETLB_PAGE_SIZE_VARIABLE                 258 config HUGETLB_PAGE_SIZE_VARIABLE
689         def_bool n                                259         def_bool n
690         help                                      260         help
691           Allows the pageblock_order value to     261           Allows the pageblock_order value to be dynamic instead of just standard
692           HUGETLB_PAGE_ORDER when there are mu    262           HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
693           on a platform.                          263           on a platform.
694                                                   264 
695           Note that the pageblock_order cannot << 
696           clamped down to MAX_PAGE_ORDER.      << 
697                                                << 
698 config CONTIG_ALLOC                               265 config CONTIG_ALLOC
699         def_bool (MEMORY_ISOLATION && COMPACTI    266         def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
700                                                   267 
701 config PCP_BATCH_SCALE_MAX                     << 
702         int "Maximum scale factor of PCP (Per- << 
703         default 5                              << 
704         range 0 6                              << 
705         help                                   << 
706           In page allocator, PCP (Per-CPU page << 
707           batches.  The batch number is scaled << 
708           allocation/free throughput.  But too << 
709           latency.  This option sets the upper << 
710           the maximum latency.                 << 
711                                                << 
712 config PHYS_ADDR_T_64BIT                          268 config PHYS_ADDR_T_64BIT
713         def_bool 64BIT                            269         def_bool 64BIT
714                                                   270 
715 config BOUNCE                                     271 config BOUNCE
716         bool "Enable bounce buffers"              272         bool "Enable bounce buffers"
717         default y                                 273         default y
718         depends on BLOCK && MMU && HIGHMEM        274         depends on BLOCK && MMU && HIGHMEM
719         help                                      275         help
720           Enable bounce buffers for devices th    276           Enable bounce buffers for devices that cannot access the full range of
721           memory available to the CPU. Enabled    277           memory available to the CPU. Enabled by default when HIGHMEM is
722           selected, but you may say n to overr    278           selected, but you may say n to override this.
723                                                   279 
                                                   >> 280 config 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 
724 config MMU_NOTIFIER                               288 config MMU_NOTIFIER
725         bool                                      289         bool
                                                   >> 290         select SRCU
726         select INTERVAL_TREE                      291         select INTERVAL_TREE
727                                                   292 
728 config KSM                                        293 config KSM
729         bool "Enable KSM for page merging"        294         bool "Enable KSM for page merging"
730         depends on MMU                            295         depends on MMU
731         select XXHASH                             296         select XXHASH
732         help                                      297         help
733           Enable Kernel Samepage Merging: KSM     298           Enable Kernel Samepage Merging: KSM periodically scans those areas
734           of an application's address space th    299           of an application's address space that an app has advised may be
735           mergeable.  When it finds pages of i    300           mergeable.  When it finds pages of identical content, it replaces
736           the many instances by a single page     301           the many instances by a single page with that content, so
737           saving memory until one or another a    302           saving memory until one or another app needs to modify the content.
738           Recommended for use with KVM, or wit    303           Recommended for use with KVM, or with other duplicative applications.
739           See Documentation/mm/ksm.rst for mor !! 304           See Documentation/vm/ksm.rst for more information: KSM is inactive
740           until a program has madvised that an    305           until a program has madvised that an area is MADV_MERGEABLE, and
741           root has set /sys/kernel/mm/ksm/run     306           root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
742                                                   307 
743 config DEFAULT_MMAP_MIN_ADDR                      308 config DEFAULT_MMAP_MIN_ADDR
744         int "Low address space to protect from    309         int "Low address space to protect from user allocation"
745         depends on MMU                            310         depends on MMU
746         default 4096                              311         default 4096
747         help                                      312         help
748           This is the portion of low virtual m    313           This is the portion of low virtual memory which should be protected
749           from userspace allocation.  Keeping     314           from userspace allocation.  Keeping a user from writing to low pages
750           can help reduce the impact of kernel    315           can help reduce the impact of kernel NULL pointer bugs.
751                                                   316 
752           For most arm64, ppc64 and x86 users  !! 317           For most ia64, ppc64 and x86 users with lots of address space
753           a value of 65536 is reasonable and s    318           a value of 65536 is reasonable and should cause no problems.
754           On arm and other archs it should not    319           On arm and other archs it should not be higher than 32768.
755           Programs which use vm86 functionalit    320           Programs which use vm86 functionality or have some need to map
756           this low address space will need CAP    321           this low address space will need CAP_SYS_RAWIO or disable this
757           protection by setting the value to 0    322           protection by setting the value to 0.
758                                                   323 
759           This value can be changed after boot    324           This value can be changed after boot using the
760           /proc/sys/vm/mmap_min_addr tunable.     325           /proc/sys/vm/mmap_min_addr tunable.
761                                                   326 
762 config ARCH_SUPPORTS_MEMORY_FAILURE               327 config ARCH_SUPPORTS_MEMORY_FAILURE
763         bool                                      328         bool
764                                                   329 
765 config MEMORY_FAILURE                             330 config MEMORY_FAILURE
766         depends on MMU                            331         depends on MMU
767         depends on ARCH_SUPPORTS_MEMORY_FAILUR    332         depends on ARCH_SUPPORTS_MEMORY_FAILURE
768         bool "Enable recovery from hardware me    333         bool "Enable recovery from hardware memory errors"
769         select MEMORY_ISOLATION                   334         select MEMORY_ISOLATION
770         select RAS                                335         select RAS
771         help                                      336         help
772           Enables code to recover from some me    337           Enables code to recover from some memory failures on systems
773           with MCA recovery. This allows a sys    338           with MCA recovery. This allows a system to continue running
774           even when some of its memory has unc    339           even when some of its memory has uncorrected errors. This requires
775           special hardware support and typical    340           special hardware support and typically ECC memory.
776                                                   341 
777 config HWPOISON_INJECT                            342 config HWPOISON_INJECT
778         tristate "HWPoison pages injector"        343         tristate "HWPoison pages injector"
779         depends on MEMORY_FAILURE && DEBUG_KER    344         depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
780         select PROC_PAGE_MONITOR                  345         select PROC_PAGE_MONITOR
781                                                   346 
782 config NOMMU_INITIAL_TRIM_EXCESS                  347 config NOMMU_INITIAL_TRIM_EXCESS
783         int "Turn on mmap() excess space trimm    348         int "Turn on mmap() excess space trimming before booting"
784         depends on !MMU                           349         depends on !MMU
785         default 1                                 350         default 1
786         help                                      351         help
787           The NOMMU mmap() frequently needs to    352           The NOMMU mmap() frequently needs to allocate large contiguous chunks
788           of memory on which to store mappings    353           of memory on which to store mappings, but it can only ask the system
789           allocator for chunks in 2^N*PAGE_SIZ    354           allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
790           more than it requires.  To deal with    355           more than it requires.  To deal with this, mmap() is able to trim off
791           the excess and return it to the allo    356           the excess and return it to the allocator.
792                                                   357 
793           If trimming is enabled, the excess i    358           If trimming is enabled, the excess is trimmed off and returned to the
794           system allocator, which can cause ex    359           system allocator, which can cause extra fragmentation, particularly
795           if there are a lot of transient proc    360           if there are a lot of transient processes.
796                                                   361 
797           If trimming is disabled, the excess     362           If trimming is disabled, the excess is kept, but not used, which for
798           long-term mappings means that the sp    363           long-term mappings means that the space is wasted.
799                                                   364 
800           Trimming can be dynamically controll    365           Trimming can be dynamically controlled through a sysctl option
801           (/proc/sys/vm/nr_trim_pages) which s    366           (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
802           excess pages there must be before tr    367           excess pages there must be before trimming should occur, or zero if
803           no trimming is to occur.                368           no trimming is to occur.
804                                                   369 
805           This option specifies the initial va    370           This option specifies the initial value of this option.  The default
806           of 1 says that all excess pages shou    371           of 1 says that all excess pages should be trimmed.
807                                                   372 
808           See Documentation/admin-guide/mm/nom    373           See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
809                                                   374 
810 config ARCH_WANT_GENERAL_HUGETLB               !! 375 config TRANSPARENT_HUGEPAGE
811         bool                                   << 
812                                                << 
813 config ARCH_WANTS_THP_SWAP                     << 
814         def_bool n                             << 
815                                                << 
816 menuconfig TRANSPARENT_HUGEPAGE                << 
817         bool "Transparent Hugepage Support"       376         bool "Transparent Hugepage Support"
818         depends on HAVE_ARCH_TRANSPARENT_HUGEP    377         depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
819         select COMPACTION                         378         select COMPACTION
820         select XARRAY_MULTI                       379         select XARRAY_MULTI
821         help                                      380         help
822           Transparent Hugepages allows the ker    381           Transparent Hugepages allows the kernel to use huge pages and
823           huge tlb transparently to the applic    382           huge tlb transparently to the applications whenever possible.
824           This feature can improve computing p    383           This feature can improve computing performance to certain
825           applications by speeding up page fau    384           applications by speeding up page faults during memory
826           allocation, by reducing the number o    385           allocation, by reducing the number of tlb misses and by speeding
827           up the pagetable walking.               386           up the pagetable walking.
828                                                   387 
829           If memory constrained on embedded, y    388           If memory constrained on embedded, you may want to say N.
830                                                   389 
831 if TRANSPARENT_HUGEPAGE                        << 
832                                                << 
833 choice                                            390 choice
834         prompt "Transparent Hugepage Support s    391         prompt "Transparent Hugepage Support sysfs defaults"
835         depends on TRANSPARENT_HUGEPAGE           392         depends on TRANSPARENT_HUGEPAGE
836         default TRANSPARENT_HUGEPAGE_ALWAYS       393         default TRANSPARENT_HUGEPAGE_ALWAYS
837         help                                      394         help
838           Selects the sysfs defaults for Trans    395           Selects the sysfs defaults for Transparent Hugepage Support.
839                                                   396 
840         config TRANSPARENT_HUGEPAGE_ALWAYS        397         config TRANSPARENT_HUGEPAGE_ALWAYS
841                 bool "always"                     398                 bool "always"
842         help                                      399         help
843           Enabling Transparent Hugepage always    400           Enabling Transparent Hugepage always, can increase the
844           memory footprint of applications wit    401           memory footprint of applications without a guaranteed
845           benefit but it will work automatical    402           benefit but it will work automatically for all applications.
846                                                   403 
847         config TRANSPARENT_HUGEPAGE_MADVISE       404         config TRANSPARENT_HUGEPAGE_MADVISE
848                 bool "madvise"                    405                 bool "madvise"
849         help                                      406         help
850           Enabling Transparent Hugepage madvis    407           Enabling Transparent Hugepage madvise, will only provide a
851           performance improvement benefit to t    408           performance improvement benefit to the applications using
852           madvise(MADV_HUGEPAGE) but it won't     409           madvise(MADV_HUGEPAGE) but it won't risk to increase the
853           memory footprint of applications wit    410           memory footprint of applications without a guaranteed
854           benefit.                                411           benefit.
855                                                << 
856         config TRANSPARENT_HUGEPAGE_NEVER      << 
857                 bool "never"                   << 
858         help                                   << 
859           Disable Transparent Hugepage by defa << 
860           enabled at runtime via sysfs.        << 
861 endchoice                                         412 endchoice
862                                                   413 
                                                   >> 414 config ARCH_WANTS_THP_SWAP
                                                   >> 415         def_bool n
                                                   >> 416 
863 config THP_SWAP                                   417 config THP_SWAP
864         def_bool y                                418         def_bool y
865         depends on TRANSPARENT_HUGEPAGE && ARC !! 419         depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP
866         help                                      420         help
867           Swap transparent huge pages in one p    421           Swap transparent huge pages in one piece, without splitting.
868           XXX: For now, swap cluster backing t    422           XXX: For now, swap cluster backing transparent huge page
869           will be split after swapout.            423           will be split after swapout.
870                                                   424 
871           For selection by architectures with     425           For selection by architectures with reasonable THP sizes.
872                                                   426 
873 config READ_ONLY_THP_FOR_FS                    << 
874         bool "Read-only THP for filesystems (E << 
875         depends on TRANSPARENT_HUGEPAGE && SHM << 
876                                                << 
877         help                                   << 
878           Allow khugepaged to put read-only fi << 
879                                                << 
880           This is marked experimental because  << 
881           support of file THPs will be develop << 
882           cycles.                              << 
883                                                << 
884 endif # TRANSPARENT_HUGEPAGE                   << 
885                                                << 
886 #                                              << 
887 # The architecture supports pgtable leaves tha << 
888 #                                              << 
889 config PGTABLE_HAS_HUGE_LEAVES                 << 
890         def_bool TRANSPARENT_HUGEPAGE || HUGET << 
891                                                << 
892 # TODO: Allow to be enabled without THP        << 
893 config ARCH_SUPPORTS_HUGE_PFNMAP               << 
894         def_bool n                             << 
895         depends on TRANSPARENT_HUGEPAGE        << 
896                                                << 
897 config ARCH_SUPPORTS_PMD_PFNMAP                << 
898         def_bool y                             << 
899         depends on ARCH_SUPPORTS_HUGE_PFNMAP & << 
900                                                << 
901 config ARCH_SUPPORTS_PUD_PFNMAP                << 
902         def_bool y                             << 
903         depends on ARCH_SUPPORTS_HUGE_PFNMAP & << 
904                                                << 
905 #                                                 427 #
906 # UP and nommu archs use km based percpu alloc    428 # UP and nommu archs use km based percpu allocator
907 #                                                 429 #
908 config NEED_PER_CPU_KM                            430 config NEED_PER_CPU_KM
909         depends on !SMP || !MMU                   431         depends on !SMP || !MMU
910         bool                                      432         bool
911         default y                                 433         default y
912                                                   434 
913 config NEED_PER_CPU_EMBED_FIRST_CHUNK          !! 435 config CLEANCACHE
914         bool                                   !! 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.
915                                                   454 
916 config NEED_PER_CPU_PAGE_FIRST_CHUNK           !! 455           If unsure, say Y to enable cleancache
917         bool                                   << 
918                                                   456 
919 config USE_PERCPU_NUMA_NODE_ID                 !! 457 config FRONTSWAP
920         bool                                   !! 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.
921                                                   470 
922 config HAVE_SETUP_PER_CPU_AREA                 !! 471           If unsure, say Y to enable frontswap.
923         bool                                   << 
924                                                   472 
925 config CMA                                        473 config CMA
926         bool "Contiguous Memory Allocator"        474         bool "Contiguous Memory Allocator"
927         depends on MMU                            475         depends on MMU
928         select MIGRATION                          476         select MIGRATION
929         select MEMORY_ISOLATION                   477         select MEMORY_ISOLATION
930         help                                      478         help
931           This enables the Contiguous Memory A    479           This enables the Contiguous Memory Allocator which allows other
932           subsystems to allocate big physicall    480           subsystems to allocate big physically-contiguous blocks of memory.
933           CMA reserves a region of memory and     481           CMA reserves a region of memory and allows only movable pages to
934           be allocated from it. This way, the     482           be allocated from it. This way, the kernel can use the memory for
935           pagecache and when a subsystem reque    483           pagecache and when a subsystem requests for contiguous area, the
936           allocated pages are migrated away to    484           allocated pages are migrated away to serve the contiguous request.
937                                                   485 
938           If unsure, say "n".                     486           If unsure, say "n".
939                                                   487 
                                                   >> 488 config 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 
940 config CMA_DEBUGFS                                497 config CMA_DEBUGFS
941         bool "CMA debugfs interface"              498         bool "CMA debugfs interface"
942         depends on CMA && DEBUG_FS                499         depends on CMA && DEBUG_FS
943         help                                      500         help
944           Turns on the DebugFS interface for C    501           Turns on the DebugFS interface for CMA.
945                                                   502 
946 config CMA_SYSFS                                  503 config CMA_SYSFS
947         bool "CMA information through sysfs in    504         bool "CMA information through sysfs interface"
948         depends on CMA && SYSFS                   505         depends on CMA && SYSFS
949         help                                      506         help
950           This option exposes some sysfs attri    507           This option exposes some sysfs attributes to get information
951           from CMA.                               508           from CMA.
952                                                   509 
953 config CMA_AREAS                                  510 config CMA_AREAS
954         int "Maximum count of the CMA areas"      511         int "Maximum count of the CMA areas"
955         depends on CMA                            512         depends on CMA
956         default 20 if NUMA                     !! 513         default 19 if NUMA
957         default 8                              !! 514         default 7
958         help                                      515         help
959           CMA allows to create CMA areas for p    516           CMA allows to create CMA areas for particular purpose, mainly,
960           used as device private area. This pa    517           used as device private area. This parameter sets the maximum
961           number of CMA area in the system.       518           number of CMA area in the system.
962                                                   519 
963           If unsure, leave the default value " !! 520           If unsure, leave the default value "7" in UMA and "19" in NUMA.
964                                                   521 
965 config MEM_SOFT_DIRTY                             522 config MEM_SOFT_DIRTY
966         bool "Track memory changes"               523         bool "Track memory changes"
967         depends on CHECKPOINT_RESTORE && HAVE_    524         depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
968         select PROC_PAGE_MONITOR                  525         select PROC_PAGE_MONITOR
969         help                                      526         help
970           This option enables memory changes t    527           This option enables memory changes tracking by introducing a
971           soft-dirty bit on pte-s. This bit it    528           soft-dirty bit on pte-s. This bit it set when someone writes
972           into a page just as regular dirty bi    529           into a page just as regular dirty bit, but unlike the latter
973           it can be cleared by hands.             530           it can be cleared by hands.
974                                                   531 
975           See Documentation/admin-guide/mm/sof    532           See Documentation/admin-guide/mm/soft-dirty.rst for more details.
976                                                   533 
                                                   >> 534 config 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 
                                                   >> 552 choice
                                                   >> 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 
                                                   >> 570 config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
                                                   >> 571         bool "Deflate"
                                                   >> 572         select CRYPTO_DEFLATE
                                                   >> 573         help
                                                   >> 574           Use the Deflate algorithm as the default compression algorithm.
                                                   >> 575 
                                                   >> 576 config ZSWAP_COMPRESSOR_DEFAULT_LZO
                                                   >> 577         bool "LZO"
                                                   >> 578         select CRYPTO_LZO
                                                   >> 579         help
                                                   >> 580           Use the LZO algorithm as the default compression algorithm.
                                                   >> 581 
                                                   >> 582 config ZSWAP_COMPRESSOR_DEFAULT_842
                                                   >> 583         bool "842"
                                                   >> 584         select CRYPTO_842
                                                   >> 585         help
                                                   >> 586           Use the 842 algorithm as the default compression algorithm.
                                                   >> 587 
                                                   >> 588 config ZSWAP_COMPRESSOR_DEFAULT_LZ4
                                                   >> 589         bool "LZ4"
                                                   >> 590         select CRYPTO_LZ4
                                                   >> 591         help
                                                   >> 592           Use the LZ4 algorithm as the default compression algorithm.
                                                   >> 593 
                                                   >> 594 config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
                                                   >> 595         bool "LZ4HC"
                                                   >> 596         select CRYPTO_LZ4HC
                                                   >> 597         help
                                                   >> 598           Use the LZ4HC algorithm as the default compression algorithm.
                                                   >> 599 
                                                   >> 600 config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
                                                   >> 601         bool "zstd"
                                                   >> 602         select CRYPTO_ZSTD
                                                   >> 603         help
                                                   >> 604           Use the zstd algorithm as the default compression algorithm.
                                                   >> 605 endchoice
                                                   >> 606 
                                                   >> 607 config 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 
                                                   >> 618 choice
                                                   >> 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 
                                                   >> 632 config ZSWAP_ZPOOL_DEFAULT_ZBUD
                                                   >> 633         bool "zbud"
                                                   >> 634         select ZBUD
                                                   >> 635         help
                                                   >> 636           Use the zbud allocator as the default allocator.
                                                   >> 637 
                                                   >> 638 config ZSWAP_ZPOOL_DEFAULT_Z3FOLD
                                                   >> 639         bool "z3fold"
                                                   >> 640         select Z3FOLD
                                                   >> 641         help
                                                   >> 642           Use the z3fold allocator as the default allocator.
                                                   >> 643 
                                                   >> 644 config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
                                                   >> 645         bool "zsmalloc"
                                                   >> 646         select ZSMALLOC
                                                   >> 647         help
                                                   >> 648           Use the zsmalloc allocator as the default allocator.
                                                   >> 649 endchoice
                                                   >> 650 
                                                   >> 651 config 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 
                                                   >> 659 config 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 
                                                   >> 669 config 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 
                                                   >> 675 config 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 
                                                   >> 685 config 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 
                                                   >> 694 config 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 
                                                   >> 705 config 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 
977 config GENERIC_EARLY_IOREMAP                      715 config GENERIC_EARLY_IOREMAP
978         bool                                      716         bool
979                                                   717 
980 config STACK_MAX_DEFAULT_SIZE_MB                  718 config STACK_MAX_DEFAULT_SIZE_MB
981         int "Default maximum user stack size f    719         int "Default maximum user stack size for 32-bit processes (MB)"
982         default 100                               720         default 100
983         range 8 2048                              721         range 8 2048
984         depends on STACK_GROWSUP && (!64BIT ||    722         depends on STACK_GROWSUP && (!64BIT || COMPAT)
985         help                                      723         help
986           This is the maximum stack size in Me    724           This is the maximum stack size in Megabytes in the VM layout of 32-bit
987           user processes when the stack grows     725           user processes when the stack grows upwards (currently only on parisc
988           arch) when the RLIMIT_STACK hard lim    726           arch) when the RLIMIT_STACK hard limit is unlimited.
989                                                   727 
990           A sane initial value is 100 MB.         728           A sane initial value is 100 MB.
991                                                   729 
992 config DEFERRED_STRUCT_PAGE_INIT                  730 config DEFERRED_STRUCT_PAGE_INIT
993         bool "Defer initialisation of struct p    731         bool "Defer initialisation of struct pages to kthreads"
994         depends on SPARSEMEM                      732         depends on SPARSEMEM
995         depends on !NEED_PER_CPU_KM               733         depends on !NEED_PER_CPU_KM
996         depends on 64BIT                          734         depends on 64BIT
997         depends on !KMSAN                      << 
998         select PADATA                             735         select PADATA
999         help                                      736         help
1000           Ordinarily all struct pages are ini    737           Ordinarily all struct pages are initialised during early boot in a
1001           single thread. On very large machin    738           single thread. On very large machines this can take a considerable
1002           amount of time. If this option is s    739           amount of time. If this option is set, large machines will bring up
1003           a subset of memmap at boot and then    740           a subset of memmap at boot and then initialise the rest in parallel.
1004           This has a potential performance im    741           This has a potential performance impact on tasks running early in the
1005           lifetime of the system until these     742           lifetime of the system until these kthreads finish the
1006           initialisation.                        743           initialisation.
1007                                                  744 
1008 config PAGE_IDLE_FLAG                            745 config PAGE_IDLE_FLAG
1009         bool                                     746         bool
1010         select PAGE_EXTENSION if !64BIT          747         select PAGE_EXTENSION if !64BIT
1011         help                                     748         help
1012           This adds PG_idle and PG_young flag    749           This adds PG_idle and PG_young flags to 'struct page'.  PTE Accessed
1013           bit writers can set the state of th    750           bit writers can set the state of the bit in the flags so that PTE
1014           Accessed bit readers may avoid dist    751           Accessed bit readers may avoid disturbance.
1015                                                  752 
1016 config IDLE_PAGE_TRACKING                        753 config IDLE_PAGE_TRACKING
1017         bool "Enable idle page tracking"         754         bool "Enable idle page tracking"
1018         depends on SYSFS && MMU                  755         depends on SYSFS && MMU
1019         select PAGE_IDLE_FLAG                    756         select PAGE_IDLE_FLAG
1020         help                                     757         help
1021           This feature allows to estimate the    758           This feature allows to estimate the amount of user pages that have
1022           not been touched during a given per    759           not been touched during a given period of time. This information can
1023           be useful to tune memory cgroup lim    760           be useful to tune memory cgroup limits and/or for job placement
1024           within a compute cluster.              761           within a compute cluster.
1025                                                  762 
1026           See Documentation/admin-guide/mm/id    763           See Documentation/admin-guide/mm/idle_page_tracking.rst for
1027           more details.                          764           more details.
1028                                                  765 
1029 # Architectures which implement cpu_dcache_is << 
1030 # whether the data caches are aliased (VIVT o << 
1031 # aliasing) need to select this.              << 
1032 config ARCH_HAS_CPU_CACHE_ALIASING            << 
1033         bool                                  << 
1034                                               << 
1035 config ARCH_HAS_CACHE_LINE_SIZE                  766 config ARCH_HAS_CACHE_LINE_SIZE
1036         bool                                     767         bool
1037                                                  768 
1038 config ARCH_HAS_CURRENT_STACK_POINTER         << 
1039         bool                                  << 
1040         help                                  << 
1041           In support of HARDENED_USERCOPY per << 
1042           checking, an architecture-agnostic  << 
1043           is needed. Once an architecture def << 
1044           register alias named "current_stack << 
1045           selected.                           << 
1046                                               << 
1047 config ARCH_HAS_PTE_DEVMAP                       769 config ARCH_HAS_PTE_DEVMAP
1048         bool                                     770         bool
1049                                                  771 
1050 config ARCH_HAS_ZONE_DMA_SET                     772 config ARCH_HAS_ZONE_DMA_SET
1051         bool                                     773         bool
1052                                                  774 
1053 config ZONE_DMA                                  775 config ZONE_DMA
1054         bool "Support DMA zone" if ARCH_HAS_Z    776         bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET
1055         default y if ARM64 || X86                777         default y if ARM64 || X86
1056                                                  778 
1057 config ZONE_DMA32                                779 config ZONE_DMA32
1058         bool "Support DMA32 zone" if ARCH_HAS    780         bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET
1059         depends on !X86_32                       781         depends on !X86_32
1060         default y if ARM64                       782         default y if ARM64
1061                                                  783 
1062 config ZONE_DEVICE                               784 config ZONE_DEVICE
1063         bool "Device memory (pmem, HMM, etc..    785         bool "Device memory (pmem, HMM, etc...) hotplug support"
1064         depends on MEMORY_HOTPLUG                786         depends on MEMORY_HOTPLUG
1065         depends on MEMORY_HOTREMOVE              787         depends on MEMORY_HOTREMOVE
1066         depends on SPARSEMEM_VMEMMAP             788         depends on SPARSEMEM_VMEMMAP
1067         depends on ARCH_HAS_PTE_DEVMAP           789         depends on ARCH_HAS_PTE_DEVMAP
1068         select XARRAY_MULTI                      790         select XARRAY_MULTI
1069                                                  791 
1070         help                                     792         help
1071           Device memory hotplug support allow    793           Device memory hotplug support allows for establishing pmem,
1072           or other device driver discovered m    794           or other device driver discovered memory regions, in the
1073           memmap. This allows pfn_to_page() l    795           memmap. This allows pfn_to_page() lookups of otherwise
1074           "device-physical" addresses which i    796           "device-physical" addresses which is needed for using a DAX
1075           mapping in an O_DIRECT operation, a    797           mapping in an O_DIRECT operation, among other things.
1076                                                  798 
1077           If FS_DAX is enabled, then say Y.      799           If FS_DAX is enabled, then say Y.
1078                                                  800 
                                                   >> 801 config DEV_PAGEMAP_OPS
                                                   >> 802         bool
                                                   >> 803 
1079 #                                                804 #
1080 # Helpers to mirror range of the CPU page tab    805 # Helpers to mirror range of the CPU page tables of a process into device page
1081 # tables.                                        806 # tables.
1082 #                                                807 #
1083 config HMM_MIRROR                                808 config HMM_MIRROR
1084         bool                                     809         bool
1085         depends on MMU                           810         depends on MMU
1086                                                  811 
1087 config GET_FREE_REGION                        << 
1088         bool                                  << 
1089                                               << 
1090 config DEVICE_PRIVATE                            812 config DEVICE_PRIVATE
1091         bool "Unaddressable device memory (GP    813         bool "Unaddressable device memory (GPU memory, ...)"
1092         depends on ZONE_DEVICE                   814         depends on ZONE_DEVICE
1093         select GET_FREE_REGION                !! 815         select DEV_PAGEMAP_OPS
1094                                                  816 
1095         help                                     817         help
1096           Allows creation of struct pages to     818           Allows creation of struct pages to represent unaddressable device
1097           memory; i.e., memory that is only a    819           memory; i.e., memory that is only accessible from the device (or
1098           group of devices). You likely also     820           group of devices). You likely also want to select HMM_MIRROR.
1099                                                  821 
1100 config VMAP_PFN                                  822 config VMAP_PFN
1101         bool                                     823         bool
1102                                                  824 
1103 config ARCH_USES_HIGH_VMA_FLAGS                  825 config ARCH_USES_HIGH_VMA_FLAGS
1104         bool                                     826         bool
1105 config ARCH_HAS_PKEYS                            827 config ARCH_HAS_PKEYS
1106         bool                                     828         bool
1107                                                  829 
1108 config ARCH_USES_PG_ARCH_2                    << 
1109         bool                                  << 
1110 config ARCH_USES_PG_ARCH_3                    << 
1111         bool                                  << 
1112                                               << 
1113 config VM_EVENT_COUNTERS                      << 
1114         default y                             << 
1115         bool "Enable VM event counters for /p << 
1116         help                                  << 
1117           VM event counters are needed for ev << 
1118           This option allows the disabling of << 
1119           on EXPERT systems.  /proc/vmstat wi << 
1120           if VM event counters are disabled.  << 
1121                                               << 
1122 config PERCPU_STATS                              830 config PERCPU_STATS
1123         bool "Collect percpu memory statistic    831         bool "Collect percpu memory statistics"
1124         help                                     832         help
1125           This feature collects and exposes s    833           This feature collects and exposes statistics via debugfs. The
1126           information includes global and per    834           information includes global and per chunk statistics, which can
1127           be used to help understand percpu m    835           be used to help understand percpu memory usage.
1128                                                  836 
1129 config GUP_TEST                                  837 config GUP_TEST
1130         bool "Enable infrastructure for get_u    838         bool "Enable infrastructure for get_user_pages()-related unit tests"
1131         depends on DEBUG_FS                      839         depends on DEBUG_FS
1132         help                                     840         help
1133           Provides /sys/kernel/debug/gup_test    841           Provides /sys/kernel/debug/gup_test, which in turn provides a way
1134           to make ioctl calls that can launch    842           to make ioctl calls that can launch kernel-based unit tests for
1135           the get_user_pages*() and pin_user_    843           the get_user_pages*() and pin_user_pages*() family of API calls.
1136                                                  844 
1137           These tests include benchmark testi    845           These tests include benchmark testing of the _fast variants of
1138           get_user_pages*() and pin_user_page    846           get_user_pages*() and pin_user_pages*(), as well as smoke tests of
1139           the non-_fast variants.                847           the non-_fast variants.
1140                                                  848 
1141           There is also a sub-test that allow    849           There is also a sub-test that allows running dump_page() on any
1142           of up to eight pages (selected by c    850           of up to eight pages (selected by command line args) within the
1143           range of user-space addresses. Thes    851           range of user-space addresses. These pages are either pinned via
1144           pin_user_pages*(), or pinned via ge    852           pin_user_pages*(), or pinned via get_user_pages*(), as specified
1145           by other command line arguments.       853           by other command line arguments.
1146                                                  854 
1147           See tools/testing/selftests/mm/gup_ !! 855           See tools/testing/selftests/vm/gup_test.c
1148                                                  856 
1149 comment "GUP_TEST needs to have DEBUG_FS enab    857 comment "GUP_TEST needs to have DEBUG_FS enabled"
1150         depends on !GUP_TEST && !DEBUG_FS        858         depends on !GUP_TEST && !DEBUG_FS
1151                                                  859 
1152 config GUP_GET_PXX_LOW_HIGH                   !! 860 config GUP_GET_PTE_LOW_HIGH
1153         bool                                     861         bool
1154                                                  862 
1155 config DMAPOOL_TEST                           !! 863 config READ_ONLY_THP_FOR_FS
1156         tristate "Enable a module to run time !! 864         bool "Read-only THP for filesystems (EXPERIMENTAL)"
1157         depends on HAS_DMA                    !! 865         depends on TRANSPARENT_HUGEPAGE && SHMEM
                                                   >> 866 
1158         help                                     867         help
1159           Provides a test module that will al !! 868           Allow khugepaged to put read-only file-backed pages in THP.
1160           various sizes and report how long i !! 869 
1161           provide a consistent way to measure !! 870           This is marked experimental because it is a new feature. Write
1162           dma_pool_alloc/free routines affect !! 871           support of file THPs will be developed in the next few release
                                                   >> 872           cycles.
1163                                                  873 
1164 config ARCH_HAS_PTE_SPECIAL                      874 config ARCH_HAS_PTE_SPECIAL
1165         bool                                     875         bool
1166                                                  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 #
                                                   >> 884 config ARCH_HAS_HUGEPD
                                                   >> 885         bool
                                                   >> 886 
1167 config MAPPING_DIRTY_HELPERS                     887 config MAPPING_DIRTY_HELPERS
1168         bool                                     888         bool
1169                                                  889 
1170 config KMAP_LOCAL                                890 config KMAP_LOCAL
1171         bool                                     891         bool
1172                                                  892 
1173 config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY           893 config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1174         bool                                     894         bool
1175                                                  895 
1176 # struct io_mapping based helper.  Selected b    896 # struct io_mapping based helper.  Selected by drivers that need them
1177 config IO_MAPPING                                897 config IO_MAPPING
1178         bool                                     898         bool
1179                                                  899 
1180 config MEMFD_CREATE                           << 
1181         bool "Enable memfd_create() system ca << 
1182                                               << 
1183 config SECRETMEM                                 900 config SECRETMEM
1184         default y                             !! 901         def_bool ARCH_HAS_SET_DIRECT_MAP && !EMBEDDED
1185         bool "Enable memfd_secret() system ca << 
1186         depends on ARCH_HAS_SET_DIRECT_MAP    << 
1187         help                                  << 
1188           Enable the memfd_secret() system ca << 
1189           memory areas visible only in the co << 
1190           not mapped to other processes and o << 
1191                                               << 
1192 config ANON_VMA_NAME                          << 
1193         bool "Anonymous VMA name support"     << 
1194         depends on PROC_FS && ADVISE_SYSCALLS << 
1195                                               << 
1196         help                                  << 
1197           Allow naming anonymous virtual memo << 
1198                                               << 
1199           This feature allows assigning names << 
1200           names can be later retrieved from / << 
1201           and help identifying individual ano << 
1202           Assigning a name to anonymous virtu << 
1203           area from being merged with adjacen << 
1204           difference in their name.           << 
1205                                               << 
1206 config HAVE_ARCH_USERFAULTFD_WP               << 
1207         bool                                  << 
1208         help                                  << 
1209           Arch has userfaultfd write protecti << 
1210                                               << 
1211 config HAVE_ARCH_USERFAULTFD_MINOR            << 
1212         bool                                  << 
1213         help                                  << 
1214           Arch has userfaultfd minor fault su << 
1215                                               << 
1216 menuconfig USERFAULTFD                        << 
1217         bool "Enable userfaultfd() system cal << 
1218         depends on MMU                        << 
1219         help                                  << 
1220           Enable the userfaultfd() system cal << 
1221           handle page faults in userland.     << 
1222                                               << 
1223 if USERFAULTFD                                << 
1224 config PTE_MARKER_UFFD_WP                     << 
1225         bool "Userfaultfd write protection su << 
1226         default y                             << 
1227         depends on HAVE_ARCH_USERFAULTFD_WP   << 
1228                                               << 
1229         help                                  << 
1230           Allows to create marker PTEs for us << 
1231           purposes.  It is required to enable << 
1232           file-backed memory types like shmem << 
1233 endif # USERFAULTFD                           << 
1234                                               << 
1235 # multi-gen LRU {                             << 
1236 config LRU_GEN                                << 
1237         bool "Multi-Gen LRU"                  << 
1238         depends on MMU                        << 
1239         # make sure folio->flags has enough s << 
1240         depends on 64BIT || !SPARSEMEM || SPA << 
1241         help                                  << 
1242           A high performance LRU implementati << 
1243           Documentation/admin-guide/mm/multig << 
1244                                               << 
1245 config LRU_GEN_ENABLED                        << 
1246         bool "Enable by default"              << 
1247         depends on LRU_GEN                    << 
1248         help                                  << 
1249           This option enables the multi-gen L << 
1250                                               << 
1251 config LRU_GEN_STATS                          << 
1252         bool "Full stats for debugging"       << 
1253         depends on LRU_GEN                    << 
1254         help                                  << 
1255           Do not enable this option unless yo << 
1256           from evicted generations for debugg << 
1257                                               << 
1258           This option has a per-memcg and per << 
1259                                               << 
1260 config LRU_GEN_WALKS_MMU                      << 
1261         def_bool y                            << 
1262         depends on LRU_GEN && ARCH_HAS_HW_PTE << 
1263 # }                                           << 
1264                                               << 
1265 config ARCH_SUPPORTS_PER_VMA_LOCK             << 
1266        def_bool n                             << 
1267                                               << 
1268 config PER_VMA_LOCK                           << 
1269         def_bool y                            << 
1270         depends on ARCH_SUPPORTS_PER_VMA_LOCK << 
1271         help                                  << 
1272           Allow per-vma locking during page f << 
1273                                               << 
1274           This feature allows locking each vi << 
1275           handling page faults instead of tak << 
1276                                               << 
1277 config LOCK_MM_AND_FIND_VMA                   << 
1278         bool                                  << 
1279         depends on !STACK_GROWSUP             << 
1280                                               << 
1281 config IOMMU_MM_DATA                          << 
1282         bool                                  << 
1283                                               << 
1284 config EXECMEM                                << 
1285         bool                                  << 
1286                                               << 
1287 config NUMA_MEMBLKS                           << 
1288         bool                                  << 
1289                                               << 
1290 config NUMA_EMU                               << 
1291         bool "NUMA emulation"                 << 
1292         depends on NUMA_MEMBLKS               << 
1293         help                                  << 
1294           Enable NUMA emulation. A flat machi << 
1295           into virtual nodes when booted with << 
1296           number of nodes. This is only usefu << 
1297                                                  902 
1298 source "mm/damon/Kconfig"                        903 source "mm/damon/Kconfig"
1299                                                  904 
1300 endmenu                                          905 endmenu
                                                      

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