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 # 5 #
6 # For some reason microblaze and nios2 hard co 6 # For some reason microblaze and nios2 hard code SWAP=n. Hopefully we can
7 # add proper SWAP support to them, in which ca 7 # add proper SWAP support to them, in which case this can be remove.
8 # 8 #
9 config ARCH_NO_SWAP 9 config ARCH_NO_SWAP
10 bool 10 bool
11 11
12 config ZPOOL 12 config ZPOOL
13 bool 13 bool
14 14
15 menuconfig SWAP 15 menuconfig SWAP
16 bool "Support for paging of anonymous 16 bool "Support for paging of anonymous memory (swap)"
17 depends on MMU && BLOCK && !ARCH_NO_SW 17 depends on MMU && BLOCK && !ARCH_NO_SWAP
18 default y 18 default y
19 help 19 help
20 This option allows you to choose whe 20 This option allows you to choose whether you want to have support
21 for so called swap devices or swap f 21 for so called swap devices or swap files in your kernel that are
22 used to provide more virtual memory 22 used to provide more virtual memory than the actual RAM present
23 in your computer. If unsure say Y. 23 in your computer. If unsure say Y.
24 24
25 config ZSWAP 25 config ZSWAP
26 bool "Compressed cache for swap pages" 26 bool "Compressed cache for swap pages"
27 depends on SWAP 27 depends on SWAP
>> 28 select FRONTSWAP
28 select CRYPTO 29 select CRYPTO
29 select ZPOOL 30 select ZPOOL
30 help 31 help
31 A lightweight compressed cache for s 32 A lightweight compressed cache for swap pages. It takes
32 pages that are in the process of bei 33 pages that are in the process of being swapped out and attempts to
33 compress them into a dynamically all 34 compress them into a dynamically allocated RAM-based memory pool.
34 This can result in a significant I/O 35 This can result in a significant I/O reduction on swap device and,
35 in the case where decompressing from 36 in the case where decompressing from RAM is faster than swap device
36 reads, can also improve workload per 37 reads, can also improve workload performance.
37 38
38 config ZSWAP_DEFAULT_ON 39 config ZSWAP_DEFAULT_ON
39 bool "Enable the compressed cache for 40 bool "Enable the compressed cache for swap pages by default"
40 depends on ZSWAP 41 depends on ZSWAP
41 help 42 help
42 If selected, the compressed cache fo 43 If selected, the compressed cache for swap pages will be enabled
43 at boot, otherwise it will be disabl 44 at boot, otherwise it will be disabled.
44 45
45 The selection made here can be overr 46 The selection made here can be overridden by using the kernel
46 command line 'zswap.enabled=' option 47 command line 'zswap.enabled=' option.
47 48
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 49 choice
63 prompt "Default compressor" 50 prompt "Default compressor"
64 depends on ZSWAP 51 depends on ZSWAP
65 default ZSWAP_COMPRESSOR_DEFAULT_LZO 52 default ZSWAP_COMPRESSOR_DEFAULT_LZO
66 help 53 help
67 Selects the default compression algo 54 Selects the default compression algorithm for the compressed cache
68 for swap pages. 55 for swap pages.
69 56
70 For an overview what kind of perform 57 For an overview what kind of performance can be expected from
71 a particular compression algorithm p 58 a particular compression algorithm please refer to the benchmarks
72 available at the following LWN page: 59 available at the following LWN page:
73 https://lwn.net/Articles/751795/ 60 https://lwn.net/Articles/751795/
74 61
75 If in doubt, select 'LZO'. 62 If in doubt, select 'LZO'.
76 63
77 The selection made here can be overr 64 The selection made here can be overridden by using the kernel
78 command line 'zswap.compressor=' opt 65 command line 'zswap.compressor=' option.
79 66
80 config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE 67 config ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
81 bool "Deflate" 68 bool "Deflate"
82 select CRYPTO_DEFLATE 69 select CRYPTO_DEFLATE
83 help 70 help
84 Use the Deflate algorithm as the def 71 Use the Deflate algorithm as the default compression algorithm.
85 72
86 config ZSWAP_COMPRESSOR_DEFAULT_LZO 73 config ZSWAP_COMPRESSOR_DEFAULT_LZO
87 bool "LZO" 74 bool "LZO"
88 select CRYPTO_LZO 75 select CRYPTO_LZO
89 help 76 help
90 Use the LZO algorithm as the default 77 Use the LZO algorithm as the default compression algorithm.
91 78
92 config ZSWAP_COMPRESSOR_DEFAULT_842 79 config ZSWAP_COMPRESSOR_DEFAULT_842
93 bool "842" 80 bool "842"
94 select CRYPTO_842 81 select CRYPTO_842
95 help 82 help
96 Use the 842 algorithm as the default 83 Use the 842 algorithm as the default compression algorithm.
97 84
98 config ZSWAP_COMPRESSOR_DEFAULT_LZ4 85 config ZSWAP_COMPRESSOR_DEFAULT_LZ4
99 bool "LZ4" 86 bool "LZ4"
100 select CRYPTO_LZ4 87 select CRYPTO_LZ4
101 help 88 help
102 Use the LZ4 algorithm as the default 89 Use the LZ4 algorithm as the default compression algorithm.
103 90
104 config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC 91 config ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
105 bool "LZ4HC" 92 bool "LZ4HC"
106 select CRYPTO_LZ4HC 93 select CRYPTO_LZ4HC
107 help 94 help
108 Use the LZ4HC algorithm as the defau 95 Use the LZ4HC algorithm as the default compression algorithm.
109 96
110 config ZSWAP_COMPRESSOR_DEFAULT_ZSTD 97 config ZSWAP_COMPRESSOR_DEFAULT_ZSTD
111 bool "zstd" 98 bool "zstd"
112 select CRYPTO_ZSTD 99 select CRYPTO_ZSTD
113 help 100 help
114 Use the zstd algorithm as the defaul 101 Use the zstd algorithm as the default compression algorithm.
115 endchoice 102 endchoice
116 103
117 config ZSWAP_COMPRESSOR_DEFAULT 104 config ZSWAP_COMPRESSOR_DEFAULT
118 string 105 string
119 depends on ZSWAP 106 depends on ZSWAP
120 default "deflate" if ZSWAP_COMPRESSOR_D 107 default "deflate" if ZSWAP_COMPRESSOR_DEFAULT_DEFLATE
121 default "lzo" if ZSWAP_COMPRESSOR_DEFAU 108 default "lzo" if ZSWAP_COMPRESSOR_DEFAULT_LZO
122 default "842" if ZSWAP_COMPRESSOR_DEFAU 109 default "842" if ZSWAP_COMPRESSOR_DEFAULT_842
123 default "lz4" if ZSWAP_COMPRESSOR_DEFAU 110 default "lz4" if ZSWAP_COMPRESSOR_DEFAULT_LZ4
124 default "lz4hc" if ZSWAP_COMPRESSOR_DEF 111 default "lz4hc" if ZSWAP_COMPRESSOR_DEFAULT_LZ4HC
125 default "zstd" if ZSWAP_COMPRESSOR_DEFA 112 default "zstd" if ZSWAP_COMPRESSOR_DEFAULT_ZSTD
126 default "" 113 default ""
127 114
128 choice 115 choice
129 prompt "Default allocator" 116 prompt "Default allocator"
130 depends on ZSWAP 117 depends on ZSWAP
131 default ZSWAP_ZPOOL_DEFAULT_ZSMALLOC i <<
132 default ZSWAP_ZPOOL_DEFAULT_ZBUD 118 default ZSWAP_ZPOOL_DEFAULT_ZBUD
133 help 119 help
134 Selects the default allocator for th 120 Selects the default allocator for the compressed cache for
135 swap pages. 121 swap pages.
136 The default is 'zbud' for compatibil 122 The default is 'zbud' for compatibility, however please do
137 read the description of each of the 123 read the description of each of the allocators below before
138 making a right choice. 124 making a right choice.
139 125
140 The selection made here can be overr 126 The selection made here can be overridden by using the kernel
141 command line 'zswap.zpool=' option. 127 command line 'zswap.zpool=' option.
142 128
143 config ZSWAP_ZPOOL_DEFAULT_ZBUD 129 config ZSWAP_ZPOOL_DEFAULT_ZBUD
144 bool "zbud" 130 bool "zbud"
145 select ZBUD 131 select ZBUD
146 help 132 help
147 Use the zbud allocator as the defaul 133 Use the zbud allocator as the default allocator.
148 134
149 config ZSWAP_ZPOOL_DEFAULT_Z3FOLD_DEPRECATED !! 135 config ZSWAP_ZPOOL_DEFAULT_Z3FOLD
150 bool "z3foldi (DEPRECATED)" !! 136 bool "z3fold"
151 select Z3FOLD_DEPRECATED !! 137 select Z3FOLD
152 help 138 help
153 Use the z3fold allocator as the defa 139 Use the z3fold allocator as the default allocator.
154 140
155 Deprecated and scheduled for removal <<
156 see CONFIG_Z3FOLD_DEPRECATED. <<
157 <<
158 config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC 141 config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
159 bool "zsmalloc" 142 bool "zsmalloc"
160 select ZSMALLOC 143 select ZSMALLOC
161 help 144 help
162 Use the zsmalloc allocator as the de 145 Use the zsmalloc allocator as the default allocator.
163 endchoice 146 endchoice
164 147
165 config ZSWAP_ZPOOL_DEFAULT 148 config ZSWAP_ZPOOL_DEFAULT
166 string 149 string
167 depends on ZSWAP 150 depends on ZSWAP
168 default "zbud" if ZSWAP_ZPOOL_DEFAULT_Z 151 default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
169 default "z3fold" if ZSWAP_ZPOOL_DEFAULT !! 152 default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD
170 default "zsmalloc" if ZSWAP_ZPOOL_DEFAU 153 default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
171 default "" 154 default ""
172 155
173 config ZBUD 156 config ZBUD
174 tristate "2:1 compression allocator (z 157 tristate "2:1 compression allocator (zbud)"
175 depends on ZSWAP 158 depends on ZSWAP
176 help 159 help
177 A special purpose allocator for stor 160 A special purpose allocator for storing compressed pages.
178 It is designed to store up to two co 161 It is designed to store up to two compressed pages per physical
179 page. While this design limits stor 162 page. While this design limits storage density, it has simple and
180 deterministic reclaim properties tha 163 deterministic reclaim properties that make it preferable to a higher
181 density approach when reclaim will b 164 density approach when reclaim will be used.
182 165
183 config Z3FOLD_DEPRECATED !! 166 config Z3FOLD
184 tristate "3:1 compression allocator (z !! 167 tristate "3:1 compression allocator (z3fold)"
185 depends on ZSWAP 168 depends on ZSWAP
186 help 169 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 170 A special purpose allocator for storing compressed pages.
192 It is designed to store up to three 171 It is designed to store up to three compressed pages per physical
193 page. It is a ZBUD derivative so the 172 page. It is a ZBUD derivative so the simplicity and determinism are
194 still there. 173 still there.
195 174
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 175 config ZSMALLOC
203 tristate 176 tristate
204 prompt "N:1 compression allocator (zsm !! 177 prompt "N:1 compression allocator (zsmalloc)" if ZSWAP
205 depends on MMU 178 depends on MMU
206 help 179 help
207 zsmalloc is a slab-based memory allo 180 zsmalloc is a slab-based memory allocator designed to store
208 pages of various compression levels 181 pages of various compression levels efficiently. It achieves
209 the highest storage density with the 182 the highest storage density with the least amount of fragmentation.
210 183
211 config ZSMALLOC_STAT 184 config ZSMALLOC_STAT
212 bool "Export zsmalloc statistics" 185 bool "Export zsmalloc statistics"
213 depends on ZSMALLOC 186 depends on ZSMALLOC
214 select DEBUG_FS 187 select DEBUG_FS
215 help 188 help
216 This option enables code in the zsma 189 This option enables code in the zsmalloc to collect various
217 statistics about what's happening in 190 statistics about what's happening in zsmalloc and exports that
218 information to userspace via debugfs 191 information to userspace via debugfs.
219 If unsure, say N. 192 If unsure, say N.
220 193
221 config ZSMALLOC_CHAIN_SIZE !! 194 menu "SLAB allocator options"
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. <<
237 195
238 For more information, see zsmalloc d !! 196 choice
>> 197 prompt "Choose SLAB allocator"
>> 198 default SLUB
>> 199 help
>> 200 This option allows to select a slab allocator.
239 201
240 menu "Slab allocator options" !! 202 config SLAB
>> 203 bool "SLAB"
>> 204 depends on !PREEMPT_RT
>> 205 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 206 help
>> 207 The regular slab allocator that is established and known to work
>> 208 well in all environments. It organizes cache hot objects in
>> 209 per cpu and per node queues.
241 210
242 config SLUB 211 config SLUB
243 def_bool y !! 212 bool "SLUB (Unqueued Allocator)"
>> 213 select HAVE_HARDENED_USERCOPY_ALLOCATOR
>> 214 help
>> 215 SLUB is a slab allocator that minimizes cache line usage
>> 216 instead of managing queues of cached objects (SLAB approach).
>> 217 Per cpu caching is realized using slabs of objects instead
>> 218 of queues of objects. SLUB can use memory efficiently
>> 219 and has enhanced diagnostics. SLUB is the default choice for
>> 220 a slab allocator.
244 221
245 config SLUB_TINY !! 222 config SLOB_DEPRECATED
246 bool "Configure for minimal memory foo <<
247 depends on EXPERT 223 depends on EXPERT
>> 224 bool "SLOB (Simple Allocator - DEPRECATED)"
>> 225 depends on !PREEMPT_RT
>> 226 help
>> 227 Deprecated and scheduled for removal in a few cycles. SLUB
>> 228 recommended as replacement. CONFIG_SLUB_TINY can be considered
>> 229 on systems with 16MB or less RAM.
>> 230
>> 231 If you need SLOB to stay, please contact linux-mm@kvack.org and
>> 232 people listed in the SLAB ALLOCATOR section of MAINTAINERS file,
>> 233 with your use case.
>> 234
>> 235 SLOB replaces the stock allocator with a drastically simpler
>> 236 allocator. SLOB is generally more space efficient but
>> 237 does not perform as well on large systems.
>> 238
>> 239 endchoice
>> 240
>> 241 config SLOB
>> 242 bool
>> 243 default y
>> 244 depends on SLOB_DEPRECATED
>> 245
>> 246 config SLUB_TINY
>> 247 bool "Configure SLUB for minimal memory footprint"
>> 248 depends on SLUB && EXPERT
248 select SLAB_MERGE_DEFAULT 249 select SLAB_MERGE_DEFAULT
249 help 250 help
250 Configures the slab allocator in a !! 251 Configures the SLUB allocator in a way to achieve minimal memory
251 footprint, sacrificing scalability, 252 footprint, sacrificing scalability, debugging and other features.
252 This is intended only for the small 253 This is intended only for the smallest system that had used the
253 SLOB allocator and is not recommend 254 SLOB allocator and is not recommended for systems with more than
254 16MB RAM. 255 16MB RAM.
255 256
256 If unsure, say N. 257 If unsure, say N.
257 258
258 config SLAB_MERGE_DEFAULT 259 config SLAB_MERGE_DEFAULT
259 bool "Allow slab caches to be merged" 260 bool "Allow slab caches to be merged"
260 default y 261 default y
>> 262 depends on SLAB || SLUB
261 help 263 help
262 For reduced kernel memory fragmentat 264 For reduced kernel memory fragmentation, slab caches can be
263 merged when they share the same size 265 merged when they share the same size and other characteristics.
264 This carries a risk of kernel heap o 266 This carries a risk of kernel heap overflows being able to
265 overwrite objects from merged caches 267 overwrite objects from merged caches (and more easily control
266 cache layout), which makes such heap 268 cache layout), which makes such heap attacks easier to exploit
267 by attackers. By keeping caches unme 269 by attackers. By keeping caches unmerged, these kinds of exploits
268 can usually only damage objects in t 270 can usually only damage objects in the same cache. To disable
269 merging at runtime, "slab_nomerge" c 271 merging at runtime, "slab_nomerge" can be passed on the kernel
270 command line. 272 command line.
271 273
272 config SLAB_FREELIST_RANDOM 274 config SLAB_FREELIST_RANDOM
273 bool "Randomize slab freelist" 275 bool "Randomize slab freelist"
274 depends on !SLUB_TINY !! 276 depends on SLAB || (SLUB && !SLUB_TINY)
275 help 277 help
276 Randomizes the freelist order used o 278 Randomizes the freelist order used on creating new pages. This
277 security feature reduces the predict 279 security feature reduces the predictability of the kernel slab
278 allocator against heap overflows. 280 allocator against heap overflows.
279 281
280 config SLAB_FREELIST_HARDENED 282 config SLAB_FREELIST_HARDENED
281 bool "Harden slab freelist metadata" 283 bool "Harden slab freelist metadata"
282 depends on !SLUB_TINY !! 284 depends on SLAB || (SLUB && !SLUB_TINY)
283 help 285 help
284 Many kernel heap attacks try to targ 286 Many kernel heap attacks try to target slab cache metadata and
285 other infrastructure. This options m 287 other infrastructure. This options makes minor performance
286 sacrifices to harden the kernel slab 288 sacrifices to harden the kernel slab allocator against common
287 freelist exploit methods. !! 289 freelist exploit methods. Some slab implementations have more
288 !! 290 sanity-checking than others. This option is most effective with
289 config SLAB_BUCKETS !! 291 CONFIG_SLUB.
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. <<
305 292
306 config SLUB_STATS 293 config SLUB_STATS
307 default n 294 default n
308 bool "Enable performance statistics" !! 295 bool "Enable SLUB performance statistics"
309 depends on SYSFS && !SLUB_TINY !! 296 depends on SLUB && SYSFS && !SLUB_TINY
310 help 297 help
311 The statistics are useful to debug s !! 298 SLUB statistics are useful to debug SLUBs allocation behavior in
312 order find ways to optimize the allo 299 order find ways to optimize the allocator. This should never be
313 enabled for production use since kee 300 enabled for production use since keeping statistics slows down
314 the allocator by a few percentage po 301 the allocator by a few percentage points. The slabinfo command
315 supports the determination of the mo 302 supports the determination of the most active slabs to figure
316 out which slabs are relevant to a pa 303 out which slabs are relevant to a particular load.
317 Try running: slabinfo -DA 304 Try running: slabinfo -DA
318 305
319 config SLUB_CPU_PARTIAL 306 config SLUB_CPU_PARTIAL
320 default y 307 default y
321 depends on SMP && !SLUB_TINY !! 308 depends on SLUB && SMP && !SLUB_TINY
322 bool "Enable per cpu partial caches" !! 309 bool "SLUB per cpu partial cache"
323 help 310 help
324 Per cpu partial caches accelerate ob 311 Per cpu partial caches accelerate objects allocation and freeing
325 that is local to a processor at the 312 that is local to a processor at the price of more indeterminism
326 in the latency of the free. On overf 313 in the latency of the free. On overflow these caches will be cleared
327 which requires the taking of locks t 314 which requires the taking of locks that may cause latency spikes.
328 Typically one would choose no for a 315 Typically one would choose no for a realtime system.
329 316
330 config RANDOM_KMALLOC_CACHES !! 317 endmenu # SLAB allocator options
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 <<
348 318
349 config SHUFFLE_PAGE_ALLOCATOR 319 config SHUFFLE_PAGE_ALLOCATOR
350 bool "Page allocator randomization" 320 bool "Page allocator randomization"
351 default SLAB_FREELIST_RANDOM && ACPI_N 321 default SLAB_FREELIST_RANDOM && ACPI_NUMA
352 help 322 help
353 Randomization of the page allocator 323 Randomization of the page allocator improves the average
354 utilization of a direct-mapped memor 324 utilization of a direct-mapped memory-side-cache. See section
355 5.2.27 Heterogeneous Memory Attribut 325 5.2.27 Heterogeneous Memory Attribute Table (HMAT) in the ACPI
356 6.2a specification for an example of 326 6.2a specification for an example of how a platform advertises
357 the presence of a memory-side-cache. 327 the presence of a memory-side-cache. There are also incidental
358 security benefits as it reduces the 328 security benefits as it reduces the predictability of page
359 allocations to compliment SLAB_FREEL 329 allocations to compliment SLAB_FREELIST_RANDOM, but the
360 default granularity of shuffling on !! 330 default granularity of shuffling on the "MAX_ORDER - 1" i.e,
361 order of pages is selected based on !! 331 10th order of pages is selected based on cache utilization
362 on x86. !! 332 benefits on x86.
363 333
364 While the randomization improves cac 334 While the randomization improves cache utilization it may
365 negatively impact workloads on platf 335 negatively impact workloads on platforms without a cache. For
366 this reason, by default, the randomi !! 336 this reason, by default, the randomization is enabled only
367 if SHUFFLE_PAGE_ALLOCATOR=y. The ran !! 337 after runtime detection of a direct-mapped memory-side-cache.
368 with the 'page_alloc.shuffle' kernel !! 338 Otherwise, the randomization may be force enabled with the
>> 339 'page_alloc.shuffle' kernel command line parameter.
369 340
370 Say Y if unsure. 341 Say Y if unsure.
371 342
372 config COMPAT_BRK 343 config COMPAT_BRK
373 bool "Disable heap randomization" 344 bool "Disable heap randomization"
374 default y 345 default y
375 help 346 help
376 Randomizing heap placement makes hea 347 Randomizing heap placement makes heap exploits harder, but it
377 also breaks ancient binaries (includ 348 also breaks ancient binaries (including anything libc5 based).
378 This option changes the bootup defau 349 This option changes the bootup default to heap randomization
379 disabled, and can be overridden at r 350 disabled, and can be overridden at runtime by setting
380 /proc/sys/kernel/randomize_va_space 351 /proc/sys/kernel/randomize_va_space to 2.
381 352
382 On non-ancient distros (post-2000 on 353 On non-ancient distros (post-2000 ones) N is usually a safe choice.
383 354
384 config MMAP_ALLOW_UNINITIALIZED 355 config MMAP_ALLOW_UNINITIALIZED
385 bool "Allow mmapped anonymous memory t 356 bool "Allow mmapped anonymous memory to be uninitialized"
386 depends on EXPERT && !MMU 357 depends on EXPERT && !MMU
387 default n 358 default n
388 help 359 help
389 Normally, and according to the Linux 360 Normally, and according to the Linux spec, anonymous memory obtained
390 from mmap() has its contents cleared 361 from mmap() has its contents cleared before it is passed to
391 userspace. Enabling this config opt 362 userspace. Enabling this config option allows you to request that
392 mmap() skip that if it is given an M 363 mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
393 providing a huge performance boost. 364 providing a huge performance boost. If this option is not enabled,
394 then the flag will be ignored. 365 then the flag will be ignored.
395 366
396 This is taken advantage of by uClibc 367 This is taken advantage of by uClibc's malloc(), and also by
397 ELF-FDPIC binfmt's brk and stack all 368 ELF-FDPIC binfmt's brk and stack allocator.
398 369
399 Because of the obvious security issu 370 Because of the obvious security issues, this option should only be
400 enabled on embedded devices where yo 371 enabled on embedded devices where you control what is run in
401 userspace. Since that isn't general 372 userspace. Since that isn't generally a problem on no-MMU systems,
402 it is normally safe to say Y here. 373 it is normally safe to say Y here.
403 374
404 See Documentation/admin-guide/mm/nom 375 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
405 376
406 config SELECT_MEMORY_MODEL 377 config SELECT_MEMORY_MODEL
407 def_bool y 378 def_bool y
408 depends on ARCH_SELECT_MEMORY_MODEL 379 depends on ARCH_SELECT_MEMORY_MODEL
409 380
410 choice 381 choice
411 prompt "Memory model" 382 prompt "Memory model"
412 depends on SELECT_MEMORY_MODEL 383 depends on SELECT_MEMORY_MODEL
413 default SPARSEMEM_MANUAL if ARCH_SPARS 384 default SPARSEMEM_MANUAL if ARCH_SPARSEMEM_DEFAULT
414 default FLATMEM_MANUAL 385 default FLATMEM_MANUAL
415 help 386 help
416 This option allows you to change som 387 This option allows you to change some of the ways that
417 Linux manages its memory internally. 388 Linux manages its memory internally. Most users will
418 only have one option here selected b 389 only have one option here selected by the architecture
419 configuration. This is normal. 390 configuration. This is normal.
420 391
421 config FLATMEM_MANUAL 392 config FLATMEM_MANUAL
422 bool "Flat Memory" 393 bool "Flat Memory"
423 depends on !ARCH_SPARSEMEM_ENABLE || A 394 depends on !ARCH_SPARSEMEM_ENABLE || ARCH_FLATMEM_ENABLE
424 help 395 help
425 This option is best suited for non-N 396 This option is best suited for non-NUMA systems with
426 flat address space. The FLATMEM is t 397 flat address space. The FLATMEM is the most efficient
427 system in terms of performance and r 398 system in terms of performance and resource consumption
428 and it is the best option for smalle 399 and it is the best option for smaller systems.
429 400
430 For systems that have holes in their 401 For systems that have holes in their physical address
431 spaces and for features like NUMA an 402 spaces and for features like NUMA and memory hotplug,
432 choose "Sparse Memory". 403 choose "Sparse Memory".
433 404
434 If unsure, choose this option (Flat 405 If unsure, choose this option (Flat Memory) over any other.
435 406
436 config SPARSEMEM_MANUAL 407 config SPARSEMEM_MANUAL
437 bool "Sparse Memory" 408 bool "Sparse Memory"
438 depends on ARCH_SPARSEMEM_ENABLE 409 depends on ARCH_SPARSEMEM_ENABLE
439 help 410 help
440 This will be the only option for som 411 This will be the only option for some systems, including
441 memory hot-plug systems. This is no 412 memory hot-plug systems. This is normal.
442 413
443 This option provides efficient suppo 414 This option provides efficient support for systems with
444 holes is their physical address spac 415 holes is their physical address space and allows memory
445 hot-plug and hot-remove. 416 hot-plug and hot-remove.
446 417
447 If unsure, choose "Flat Memory" over 418 If unsure, choose "Flat Memory" over this option.
448 419
449 endchoice 420 endchoice
450 421
451 config SPARSEMEM 422 config SPARSEMEM
452 def_bool y 423 def_bool y
453 depends on (!SELECT_MEMORY_MODEL && AR 424 depends on (!SELECT_MEMORY_MODEL && ARCH_SPARSEMEM_ENABLE) || SPARSEMEM_MANUAL
454 425
455 config FLATMEM 426 config FLATMEM
456 def_bool y 427 def_bool y
457 depends on !SPARSEMEM || FLATMEM_MANUA 428 depends on !SPARSEMEM || FLATMEM_MANUAL
458 429
459 # 430 #
460 # SPARSEMEM_EXTREME (which is the default) doe 431 # SPARSEMEM_EXTREME (which is the default) does some bootmem
461 # allocations when sparse_init() is called. I 432 # allocations when sparse_init() is called. If this cannot
462 # be done on your architecture, select this op 433 # be done on your architecture, select this option. However,
463 # statically allocating the mem_section[] arra 434 # statically allocating the mem_section[] array can potentially
464 # consume vast quantities of .bss, so be caref 435 # consume vast quantities of .bss, so be careful.
465 # 436 #
466 # This option will also potentially produce sm 437 # This option will also potentially produce smaller runtime code
467 # with gcc 3.4 and later. 438 # with gcc 3.4 and later.
468 # 439 #
469 config SPARSEMEM_STATIC 440 config SPARSEMEM_STATIC
470 bool 441 bool
471 442
472 # 443 #
473 # Architecture platforms which require a two l 444 # Architecture platforms which require a two level mem_section in SPARSEMEM
474 # must select this option. This is usually for 445 # must select this option. This is usually for architecture platforms with
475 # an extremely sparse physical address space. 446 # an extremely sparse physical address space.
476 # 447 #
477 config SPARSEMEM_EXTREME 448 config SPARSEMEM_EXTREME
478 def_bool y 449 def_bool y
479 depends on SPARSEMEM && !SPARSEMEM_STA 450 depends on SPARSEMEM && !SPARSEMEM_STATIC
480 451
481 config SPARSEMEM_VMEMMAP_ENABLE 452 config SPARSEMEM_VMEMMAP_ENABLE
482 bool 453 bool
483 454
484 config SPARSEMEM_VMEMMAP 455 config SPARSEMEM_VMEMMAP
485 bool "Sparse Memory virtual memmap" 456 bool "Sparse Memory virtual memmap"
486 depends on SPARSEMEM && SPARSEMEM_VMEM 457 depends on SPARSEMEM && SPARSEMEM_VMEMMAP_ENABLE
487 default y 458 default y
488 help 459 help
489 SPARSEMEM_VMEMMAP uses a virtually m 460 SPARSEMEM_VMEMMAP uses a virtually mapped memmap to optimise
490 pfn_to_page and page_to_pfn operatio 461 pfn_to_page and page_to_pfn operations. This is the most
491 efficient option when sufficient ker 462 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 <<
501 463
502 config HAVE_MEMBLOCK_PHYS_MAP 464 config HAVE_MEMBLOCK_PHYS_MAP
503 bool 465 bool
504 466
505 config HAVE_GUP_FAST !! 467 config HAVE_FAST_GUP
506 depends on MMU 468 depends on MMU
507 bool 469 bool
508 470
509 # Don't discard allocated memory used to track 471 # Don't discard allocated memory used to track "memory" and "reserved" memblocks
510 # after early boot, so it can still be used to 472 # after early boot, so it can still be used to test for validity of memory.
511 # Also, memblocks are updated with memory hot( 473 # Also, memblocks are updated with memory hot(un)plug.
512 config ARCH_KEEP_MEMBLOCK 474 config ARCH_KEEP_MEMBLOCK
513 bool 475 bool
514 476
515 # Keep arch NUMA mapping infrastructure post-i 477 # Keep arch NUMA mapping infrastructure post-init.
516 config NUMA_KEEP_MEMINFO 478 config NUMA_KEEP_MEMINFO
517 bool 479 bool
518 480
519 config MEMORY_ISOLATION 481 config MEMORY_ISOLATION
520 bool 482 bool
521 483
522 # IORESOURCE_SYSTEM_RAM regions in the kernel 484 # IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
523 # IORESOURCE_EXCLUSIVE cannot be mapped to use 485 # IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
524 # /dev/mem. 486 # /dev/mem.
525 config EXCLUSIVE_SYSTEM_RAM 487 config EXCLUSIVE_SYSTEM_RAM
526 def_bool y 488 def_bool y
527 depends on !DEVMEM || STRICT_DEVMEM 489 depends on !DEVMEM || STRICT_DEVMEM
528 490
529 # 491 #
530 # Only be set on architectures that have compl 492 # Only be set on architectures that have completely implemented memory hotplug
531 # feature. If you are not sure, don't touch it 493 # feature. If you are not sure, don't touch it.
532 # 494 #
533 config HAVE_BOOTMEM_INFO_NODE 495 config HAVE_BOOTMEM_INFO_NODE
534 def_bool n 496 def_bool n
535 497
536 config ARCH_ENABLE_MEMORY_HOTPLUG 498 config ARCH_ENABLE_MEMORY_HOTPLUG
537 bool 499 bool
538 500
539 config ARCH_ENABLE_MEMORY_HOTREMOVE 501 config ARCH_ENABLE_MEMORY_HOTREMOVE
540 bool 502 bool
541 503
542 # eventually, we can have this option just 'se 504 # eventually, we can have this option just 'select SPARSEMEM'
543 menuconfig MEMORY_HOTPLUG 505 menuconfig MEMORY_HOTPLUG
544 bool "Memory hotplug" 506 bool "Memory hotplug"
545 select MEMORY_ISOLATION 507 select MEMORY_ISOLATION
546 depends on SPARSEMEM 508 depends on SPARSEMEM
547 depends on ARCH_ENABLE_MEMORY_HOTPLUG 509 depends on ARCH_ENABLE_MEMORY_HOTPLUG
548 depends on 64BIT 510 depends on 64BIT
549 select NUMA_KEEP_MEMINFO if NUMA 511 select NUMA_KEEP_MEMINFO if NUMA
550 512
551 if MEMORY_HOTPLUG 513 if MEMORY_HOTPLUG
552 514
553 config MEMORY_HOTPLUG_DEFAULT_ONLINE 515 config MEMORY_HOTPLUG_DEFAULT_ONLINE
554 bool "Online the newly added memory bl 516 bool "Online the newly added memory blocks by default"
555 depends on MEMORY_HOTPLUG 517 depends on MEMORY_HOTPLUG
556 help 518 help
557 This option sets the default policy 519 This option sets the default policy setting for memory hotplug
558 onlining policy (/sys/devices/system 520 onlining policy (/sys/devices/system/memory/auto_online_blocks) which
559 determines what happens to newly add 521 determines what happens to newly added memory regions. Policy setting
560 can always be changed at runtime. 522 can always be changed at runtime.
561 See Documentation/admin-guide/mm/mem 523 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
562 524
563 Say Y here if you want all hot-plugg 525 Say Y here if you want all hot-plugged memory blocks to appear in
564 'online' state by default. 526 'online' state by default.
565 Say N here if you want the default p 527 Say N here if you want the default policy to keep all hot-plugged
566 memory blocks in 'offline' state. 528 memory blocks in 'offline' state.
567 529
568 config MEMORY_HOTREMOVE 530 config MEMORY_HOTREMOVE
569 bool "Allow for memory hot remove" 531 bool "Allow for memory hot remove"
570 select HAVE_BOOTMEM_INFO_NODE if (X86_ 532 select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
571 depends on MEMORY_HOTPLUG && ARCH_ENAB 533 depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
572 depends on MIGRATION 534 depends on MIGRATION
573 535
574 config MHP_MEMMAP_ON_MEMORY 536 config MHP_MEMMAP_ON_MEMORY
575 def_bool y 537 def_bool y
576 depends on MEMORY_HOTPLUG && SPARSEMEM 538 depends on MEMORY_HOTPLUG && SPARSEMEM_VMEMMAP
577 depends on ARCH_MHP_MEMMAP_ON_MEMORY_E 539 depends on ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
578 540
579 endif # MEMORY_HOTPLUG 541 endif # MEMORY_HOTPLUG
580 542
581 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE <<
582 bool <<
583 <<
584 # Heavily threaded applications may benefit fr 543 # Heavily threaded applications may benefit from splitting the mm-wide
585 # page_table_lock, so that faults on different 544 # page_table_lock, so that faults on different parts of the user address
586 # space can be handled with less contention: s 545 # space can be handled with less contention: split it at this NR_CPUS.
587 # Default to 4 for wider testing, though 8 mig 546 # Default to 4 for wider testing, though 8 might be more appropriate.
588 # ARM's adjust_pte (unused if VIPT) depends on 547 # ARM's adjust_pte (unused if VIPT) depends on mm-wide page_table_lock.
589 # PA-RISC 7xxx's spinlock_t would enlarge stru 548 # PA-RISC 7xxx's spinlock_t would enlarge struct page from 32 to 44 bytes.
590 # SPARC32 allocates multiple pte tables within 549 # SPARC32 allocates multiple pte tables within a single page, and therefore
591 # a per-page lock leads to problems when multi 550 # a per-page lock leads to problems when multiple tables need to be locked
592 # at the same time (e.g. copy_page_range()). 551 # at the same time (e.g. copy_page_range()).
593 # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock 552 # DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC spinlock_t also enlarge struct page.
594 # 553 #
595 config SPLIT_PTE_PTLOCKS !! 554 config SPLIT_PTLOCK_CPUS
596 def_bool y !! 555 int
597 depends on MMU !! 556 default "999999" if !MMU
598 depends on SMP !! 557 default "999999" if ARM && !CPU_CACHE_VIPT
599 depends on NR_CPUS >= 4 !! 558 default "999999" if PARISC && !PA20
600 depends on !ARM || CPU_CACHE_VIPT !! 559 default "999999" if SPARC32
601 depends on !PARISC || PA20 !! 560 default "4"
602 depends on !SPARC32 <<
603 561
604 config ARCH_ENABLE_SPLIT_PMD_PTLOCK 562 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
605 bool 563 bool
606 564
607 config SPLIT_PMD_PTLOCKS <<
608 def_bool y <<
609 depends on SPLIT_PTE_PTLOCKS && ARCH_E <<
610 <<
611 # 565 #
612 # support for memory balloon 566 # support for memory balloon
613 config MEMORY_BALLOON 567 config MEMORY_BALLOON
614 bool 568 bool
615 569
616 # 570 #
617 # support for memory balloon compaction 571 # support for memory balloon compaction
618 config BALLOON_COMPACTION 572 config BALLOON_COMPACTION
619 bool "Allow for balloon memory compact 573 bool "Allow for balloon memory compaction/migration"
620 default y !! 574 def_bool y
621 depends on COMPACTION && MEMORY_BALLOO 575 depends on COMPACTION && MEMORY_BALLOON
622 help 576 help
623 Memory fragmentation introduced by b 577 Memory fragmentation introduced by ballooning might reduce
624 significantly the number of 2MB cont 578 significantly the number of 2MB contiguous memory blocks that can be
625 used within a guest, thus imposing p 579 used within a guest, thus imposing performance penalties associated
626 with the reduced number of transpare 580 with the reduced number of transparent huge pages that could be used
627 by the guest workload. Allowing the 581 by the guest workload. Allowing the compaction & migration for memory
628 pages enlisted as being part of memo 582 pages enlisted as being part of memory balloon devices avoids the
629 scenario aforementioned and helps im 583 scenario aforementioned and helps improving memory defragmentation.
630 584
631 # 585 #
632 # support for memory compaction 586 # support for memory compaction
633 config COMPACTION 587 config COMPACTION
634 bool "Allow for memory compaction" 588 bool "Allow for memory compaction"
635 default y !! 589 def_bool y
636 select MIGRATION 590 select MIGRATION
637 depends on MMU 591 depends on MMU
638 help 592 help
639 Compaction is the only memory manage 593 Compaction is the only memory management component to form
640 high order (larger physically contig 594 high order (larger physically contiguous) memory blocks
641 reliably. The page allocator relies 595 reliably. The page allocator relies on compaction heavily and
642 the lack of the feature can lead to 596 the lack of the feature can lead to unexpected OOM killer
643 invocations for high order memory re 597 invocations for high order memory requests. You shouldn't
644 disable this option unless there rea 598 disable this option unless there really is a strong reason for
645 it and then we would be really inter 599 it and then we would be really interested to hear about that at
646 linux-mm@kvack.org. 600 linux-mm@kvack.org.
647 601
648 config COMPACT_UNEVICTABLE_DEFAULT 602 config COMPACT_UNEVICTABLE_DEFAULT
649 int 603 int
650 depends on COMPACTION 604 depends on COMPACTION
651 default 0 if PREEMPT_RT 605 default 0 if PREEMPT_RT
652 default 1 606 default 1
653 607
654 # 608 #
655 # support for free page reporting 609 # support for free page reporting
656 config PAGE_REPORTING 610 config PAGE_REPORTING
657 bool "Free page reporting" 611 bool "Free page reporting"
>> 612 def_bool n
658 help 613 help
659 Free page reporting allows for the i 614 Free page reporting allows for the incremental acquisition of
660 free pages from the buddy allocator 615 free pages from the buddy allocator for the purpose of reporting
661 those pages to another entity, such 616 those pages to another entity, such as a hypervisor, so that the
662 memory can be freed within the host 617 memory can be freed within the host for other uses.
663 618
664 # 619 #
665 # support for page migration 620 # support for page migration
666 # 621 #
667 config MIGRATION 622 config MIGRATION
668 bool "Page migration" 623 bool "Page migration"
669 default y !! 624 def_bool y
670 depends on (NUMA || ARCH_ENABLE_MEMORY 625 depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
671 help 626 help
672 Allows the migration of the physical 627 Allows the migration of the physical location of pages of processes
673 while the virtual addresses are not 628 while the virtual addresses are not changed. This is useful in
674 two situations. The first is on NUMA 629 two situations. The first is on NUMA systems to put pages nearer
675 to the processors accessing. The sec 630 to the processors accessing. The second is when allocating huge
676 pages as migration can relocate page 631 pages as migration can relocate pages to satisfy a huge page
677 allocation instead of reclaiming. 632 allocation instead of reclaiming.
678 633
679 config DEVICE_MIGRATION 634 config DEVICE_MIGRATION
680 def_bool MIGRATION && ZONE_DEVICE 635 def_bool MIGRATION && ZONE_DEVICE
681 636
682 config ARCH_ENABLE_HUGEPAGE_MIGRATION 637 config ARCH_ENABLE_HUGEPAGE_MIGRATION
683 bool 638 bool
684 639
685 config ARCH_ENABLE_THP_MIGRATION 640 config ARCH_ENABLE_THP_MIGRATION
686 bool 641 bool
687 642
688 config HUGETLB_PAGE_SIZE_VARIABLE 643 config HUGETLB_PAGE_SIZE_VARIABLE
689 def_bool n 644 def_bool n
690 help 645 help
691 Allows the pageblock_order value to 646 Allows the pageblock_order value to be dynamic instead of just standard
692 HUGETLB_PAGE_ORDER when there are mu 647 HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
693 on a platform. 648 on a platform.
694 649
695 Note that the pageblock_order cannot !! 650 Note that the pageblock_order cannot exceed MAX_ORDER - 1 and will be
696 clamped down to MAX_PAGE_ORDER. !! 651 clamped down to MAX_ORDER - 1.
697 652
698 config CONTIG_ALLOC 653 config CONTIG_ALLOC
699 def_bool (MEMORY_ISOLATION && COMPACTI 654 def_bool (MEMORY_ISOLATION && COMPACTION) || CMA
700 655
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 656 config PHYS_ADDR_T_64BIT
713 def_bool 64BIT 657 def_bool 64BIT
714 658
715 config BOUNCE 659 config BOUNCE
716 bool "Enable bounce buffers" 660 bool "Enable bounce buffers"
717 default y 661 default y
718 depends on BLOCK && MMU && HIGHMEM 662 depends on BLOCK && MMU && HIGHMEM
719 help 663 help
720 Enable bounce buffers for devices th 664 Enable bounce buffers for devices that cannot access the full range of
721 memory available to the CPU. Enabled 665 memory available to the CPU. Enabled by default when HIGHMEM is
722 selected, but you may say n to overr 666 selected, but you may say n to override this.
723 667
724 config MMU_NOTIFIER 668 config MMU_NOTIFIER
725 bool 669 bool
>> 670 select SRCU
726 select INTERVAL_TREE 671 select INTERVAL_TREE
727 672
728 config KSM 673 config KSM
729 bool "Enable KSM for page merging" 674 bool "Enable KSM for page merging"
730 depends on MMU 675 depends on MMU
731 select XXHASH 676 select XXHASH
732 help 677 help
733 Enable Kernel Samepage Merging: KSM 678 Enable Kernel Samepage Merging: KSM periodically scans those areas
734 of an application's address space th 679 of an application's address space that an app has advised may be
735 mergeable. When it finds pages of i 680 mergeable. When it finds pages of identical content, it replaces
736 the many instances by a single page 681 the many instances by a single page with that content, so
737 saving memory until one or another a 682 saving memory until one or another app needs to modify the content.
738 Recommended for use with KVM, or wit 683 Recommended for use with KVM, or with other duplicative applications.
739 See Documentation/mm/ksm.rst for mor 684 See Documentation/mm/ksm.rst for more information: KSM is inactive
740 until a program has madvised that an 685 until a program has madvised that an area is MADV_MERGEABLE, and
741 root has set /sys/kernel/mm/ksm/run 686 root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
742 687
743 config DEFAULT_MMAP_MIN_ADDR 688 config DEFAULT_MMAP_MIN_ADDR
744 int "Low address space to protect from 689 int "Low address space to protect from user allocation"
745 depends on MMU 690 depends on MMU
746 default 4096 691 default 4096
747 help 692 help
748 This is the portion of low virtual m 693 This is the portion of low virtual memory which should be protected
749 from userspace allocation. Keeping 694 from userspace allocation. Keeping a user from writing to low pages
750 can help reduce the impact of kernel 695 can help reduce the impact of kernel NULL pointer bugs.
751 696
752 For most arm64, ppc64 and x86 users !! 697 For most ia64, ppc64 and x86 users with lots of address space
753 a value of 65536 is reasonable and s 698 a value of 65536 is reasonable and should cause no problems.
754 On arm and other archs it should not 699 On arm and other archs it should not be higher than 32768.
755 Programs which use vm86 functionalit 700 Programs which use vm86 functionality or have some need to map
756 this low address space will need CAP 701 this low address space will need CAP_SYS_RAWIO or disable this
757 protection by setting the value to 0 702 protection by setting the value to 0.
758 703
759 This value can be changed after boot 704 This value can be changed after boot using the
760 /proc/sys/vm/mmap_min_addr tunable. 705 /proc/sys/vm/mmap_min_addr tunable.
761 706
762 config ARCH_SUPPORTS_MEMORY_FAILURE 707 config ARCH_SUPPORTS_MEMORY_FAILURE
763 bool 708 bool
764 709
765 config MEMORY_FAILURE 710 config MEMORY_FAILURE
766 depends on MMU 711 depends on MMU
767 depends on ARCH_SUPPORTS_MEMORY_FAILUR 712 depends on ARCH_SUPPORTS_MEMORY_FAILURE
768 bool "Enable recovery from hardware me 713 bool "Enable recovery from hardware memory errors"
769 select MEMORY_ISOLATION 714 select MEMORY_ISOLATION
770 select RAS 715 select RAS
771 help 716 help
772 Enables code to recover from some me 717 Enables code to recover from some memory failures on systems
773 with MCA recovery. This allows a sys 718 with MCA recovery. This allows a system to continue running
774 even when some of its memory has unc 719 even when some of its memory has uncorrected errors. This requires
775 special hardware support and typical 720 special hardware support and typically ECC memory.
776 721
777 config HWPOISON_INJECT 722 config HWPOISON_INJECT
778 tristate "HWPoison pages injector" 723 tristate "HWPoison pages injector"
779 depends on MEMORY_FAILURE && DEBUG_KER 724 depends on MEMORY_FAILURE && DEBUG_KERNEL && PROC_FS
780 select PROC_PAGE_MONITOR 725 select PROC_PAGE_MONITOR
781 726
782 config NOMMU_INITIAL_TRIM_EXCESS 727 config NOMMU_INITIAL_TRIM_EXCESS
783 int "Turn on mmap() excess space trimm 728 int "Turn on mmap() excess space trimming before booting"
784 depends on !MMU 729 depends on !MMU
785 default 1 730 default 1
786 help 731 help
787 The NOMMU mmap() frequently needs to 732 The NOMMU mmap() frequently needs to allocate large contiguous chunks
788 of memory on which to store mappings 733 of memory on which to store mappings, but it can only ask the system
789 allocator for chunks in 2^N*PAGE_SIZ 734 allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently
790 more than it requires. To deal with 735 more than it requires. To deal with this, mmap() is able to trim off
791 the excess and return it to the allo 736 the excess and return it to the allocator.
792 737
793 If trimming is enabled, the excess i 738 If trimming is enabled, the excess is trimmed off and returned to the
794 system allocator, which can cause ex 739 system allocator, which can cause extra fragmentation, particularly
795 if there are a lot of transient proc 740 if there are a lot of transient processes.
796 741
797 If trimming is disabled, the excess 742 If trimming is disabled, the excess is kept, but not used, which for
798 long-term mappings means that the sp 743 long-term mappings means that the space is wasted.
799 744
800 Trimming can be dynamically controll 745 Trimming can be dynamically controlled through a sysctl option
801 (/proc/sys/vm/nr_trim_pages) which s 746 (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of
802 excess pages there must be before tr 747 excess pages there must be before trimming should occur, or zero if
803 no trimming is to occur. 748 no trimming is to occur.
804 749
805 This option specifies the initial va 750 This option specifies the initial value of this option. The default
806 of 1 says that all excess pages shou 751 of 1 says that all excess pages should be trimmed.
807 752
808 See Documentation/admin-guide/mm/nom 753 See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
809 754
810 config ARCH_WANT_GENERAL_HUGETLB 755 config ARCH_WANT_GENERAL_HUGETLB
811 bool 756 bool
812 757
813 config ARCH_WANTS_THP_SWAP 758 config ARCH_WANTS_THP_SWAP
814 def_bool n 759 def_bool n
815 760
816 menuconfig TRANSPARENT_HUGEPAGE 761 menuconfig TRANSPARENT_HUGEPAGE
817 bool "Transparent Hugepage Support" 762 bool "Transparent Hugepage Support"
818 depends on HAVE_ARCH_TRANSPARENT_HUGEP 763 depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
819 select COMPACTION 764 select COMPACTION
820 select XARRAY_MULTI 765 select XARRAY_MULTI
821 help 766 help
822 Transparent Hugepages allows the ker 767 Transparent Hugepages allows the kernel to use huge pages and
823 huge tlb transparently to the applic 768 huge tlb transparently to the applications whenever possible.
824 This feature can improve computing p 769 This feature can improve computing performance to certain
825 applications by speeding up page fau 770 applications by speeding up page faults during memory
826 allocation, by reducing the number o 771 allocation, by reducing the number of tlb misses and by speeding
827 up the pagetable walking. 772 up the pagetable walking.
828 773
829 If memory constrained on embedded, y 774 If memory constrained on embedded, you may want to say N.
830 775
831 if TRANSPARENT_HUGEPAGE 776 if TRANSPARENT_HUGEPAGE
832 777
833 choice 778 choice
834 prompt "Transparent Hugepage Support s 779 prompt "Transparent Hugepage Support sysfs defaults"
835 depends on TRANSPARENT_HUGEPAGE 780 depends on TRANSPARENT_HUGEPAGE
836 default TRANSPARENT_HUGEPAGE_ALWAYS 781 default TRANSPARENT_HUGEPAGE_ALWAYS
837 help 782 help
838 Selects the sysfs defaults for Trans 783 Selects the sysfs defaults for Transparent Hugepage Support.
839 784
840 config TRANSPARENT_HUGEPAGE_ALWAYS 785 config TRANSPARENT_HUGEPAGE_ALWAYS
841 bool "always" 786 bool "always"
842 help 787 help
843 Enabling Transparent Hugepage always 788 Enabling Transparent Hugepage always, can increase the
844 memory footprint of applications wit 789 memory footprint of applications without a guaranteed
845 benefit but it will work automatical 790 benefit but it will work automatically for all applications.
846 791
847 config TRANSPARENT_HUGEPAGE_MADVISE 792 config TRANSPARENT_HUGEPAGE_MADVISE
848 bool "madvise" 793 bool "madvise"
849 help 794 help
850 Enabling Transparent Hugepage madvis 795 Enabling Transparent Hugepage madvise, will only provide a
851 performance improvement benefit to t 796 performance improvement benefit to the applications using
852 madvise(MADV_HUGEPAGE) but it won't 797 madvise(MADV_HUGEPAGE) but it won't risk to increase the
853 memory footprint of applications wit 798 memory footprint of applications without a guaranteed
854 benefit. 799 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 800 endchoice
862 801
863 config THP_SWAP 802 config THP_SWAP
864 def_bool y 803 def_bool y
865 depends on TRANSPARENT_HUGEPAGE && ARC 804 depends on TRANSPARENT_HUGEPAGE && ARCH_WANTS_THP_SWAP && SWAP && 64BIT
866 help 805 help
867 Swap transparent huge pages in one p 806 Swap transparent huge pages in one piece, without splitting.
868 XXX: For now, swap cluster backing t 807 XXX: For now, swap cluster backing transparent huge page
869 will be split after swapout. 808 will be split after swapout.
870 809
871 For selection by architectures with 810 For selection by architectures with reasonable THP sizes.
872 811
873 config READ_ONLY_THP_FOR_FS 812 config READ_ONLY_THP_FOR_FS
874 bool "Read-only THP for filesystems (E 813 bool "Read-only THP for filesystems (EXPERIMENTAL)"
875 depends on TRANSPARENT_HUGEPAGE && SHM 814 depends on TRANSPARENT_HUGEPAGE && SHMEM
876 815
877 help 816 help
878 Allow khugepaged to put read-only fi 817 Allow khugepaged to put read-only file-backed pages in THP.
879 818
880 This is marked experimental because 819 This is marked experimental because it is a new feature. Write
881 support of file THPs will be develop 820 support of file THPs will be developed in the next few release
882 cycles. 821 cycles.
883 822
884 endif # TRANSPARENT_HUGEPAGE 823 endif # TRANSPARENT_HUGEPAGE
885 824
886 # 825 #
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 # <<
906 # UP and nommu archs use km based percpu alloc 826 # UP and nommu archs use km based percpu allocator
907 # 827 #
908 config NEED_PER_CPU_KM 828 config NEED_PER_CPU_KM
909 depends on !SMP || !MMU 829 depends on !SMP || !MMU
910 bool 830 bool
911 default y 831 default y
912 832
913 config NEED_PER_CPU_EMBED_FIRST_CHUNK 833 config NEED_PER_CPU_EMBED_FIRST_CHUNK
914 bool 834 bool
915 835
916 config NEED_PER_CPU_PAGE_FIRST_CHUNK 836 config NEED_PER_CPU_PAGE_FIRST_CHUNK
917 bool 837 bool
918 838
919 config USE_PERCPU_NUMA_NODE_ID 839 config USE_PERCPU_NUMA_NODE_ID
920 bool 840 bool
921 841
922 config HAVE_SETUP_PER_CPU_AREA 842 config HAVE_SETUP_PER_CPU_AREA
923 bool 843 bool
924 844
>> 845 config FRONTSWAP
>> 846 bool
>> 847
925 config CMA 848 config CMA
926 bool "Contiguous Memory Allocator" 849 bool "Contiguous Memory Allocator"
927 depends on MMU 850 depends on MMU
928 select MIGRATION 851 select MIGRATION
929 select MEMORY_ISOLATION 852 select MEMORY_ISOLATION
930 help 853 help
931 This enables the Contiguous Memory A 854 This enables the Contiguous Memory Allocator which allows other
932 subsystems to allocate big physicall 855 subsystems to allocate big physically-contiguous blocks of memory.
933 CMA reserves a region of memory and 856 CMA reserves a region of memory and allows only movable pages to
934 be allocated from it. This way, the 857 be allocated from it. This way, the kernel can use the memory for
935 pagecache and when a subsystem reque 858 pagecache and when a subsystem requests for contiguous area, the
936 allocated pages are migrated away to 859 allocated pages are migrated away to serve the contiguous request.
937 860
938 If unsure, say "n". 861 If unsure, say "n".
939 862
>> 863 config CMA_DEBUG
>> 864 bool "CMA debug messages (DEVELOPMENT)"
>> 865 depends on DEBUG_KERNEL && CMA
>> 866 help
>> 867 Turns on debug messages in CMA. This produces KERN_DEBUG
>> 868 messages for every CMA call as well as various messages while
>> 869 processing calls such as dma_alloc_from_contiguous().
>> 870 This option does not affect warning and error messages.
>> 871
940 config CMA_DEBUGFS 872 config CMA_DEBUGFS
941 bool "CMA debugfs interface" 873 bool "CMA debugfs interface"
942 depends on CMA && DEBUG_FS 874 depends on CMA && DEBUG_FS
943 help 875 help
944 Turns on the DebugFS interface for C 876 Turns on the DebugFS interface for CMA.
945 877
946 config CMA_SYSFS 878 config CMA_SYSFS
947 bool "CMA information through sysfs in 879 bool "CMA information through sysfs interface"
948 depends on CMA && SYSFS 880 depends on CMA && SYSFS
949 help 881 help
950 This option exposes some sysfs attri 882 This option exposes some sysfs attributes to get information
951 from CMA. 883 from CMA.
952 884
953 config CMA_AREAS 885 config CMA_AREAS
954 int "Maximum count of the CMA areas" 886 int "Maximum count of the CMA areas"
955 depends on CMA 887 depends on CMA
956 default 20 if NUMA !! 888 default 19 if NUMA
957 default 8 !! 889 default 7
958 help 890 help
959 CMA allows to create CMA areas for p 891 CMA allows to create CMA areas for particular purpose, mainly,
960 used as device private area. This pa 892 used as device private area. This parameter sets the maximum
961 number of CMA area in the system. 893 number of CMA area in the system.
962 894
963 If unsure, leave the default value " !! 895 If unsure, leave the default value "7" in UMA and "19" in NUMA.
964 896
965 config MEM_SOFT_DIRTY 897 config MEM_SOFT_DIRTY
966 bool "Track memory changes" 898 bool "Track memory changes"
967 depends on CHECKPOINT_RESTORE && HAVE_ 899 depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
968 select PROC_PAGE_MONITOR 900 select PROC_PAGE_MONITOR
969 help 901 help
970 This option enables memory changes t 902 This option enables memory changes tracking by introducing a
971 soft-dirty bit on pte-s. This bit it 903 soft-dirty bit on pte-s. This bit it set when someone writes
972 into a page just as regular dirty bi 904 into a page just as regular dirty bit, but unlike the latter
973 it can be cleared by hands. 905 it can be cleared by hands.
974 906
975 See Documentation/admin-guide/mm/sof 907 See Documentation/admin-guide/mm/soft-dirty.rst for more details.
976 908
977 config GENERIC_EARLY_IOREMAP 909 config GENERIC_EARLY_IOREMAP
978 bool 910 bool
979 911
980 config STACK_MAX_DEFAULT_SIZE_MB 912 config STACK_MAX_DEFAULT_SIZE_MB
981 int "Default maximum user stack size f 913 int "Default maximum user stack size for 32-bit processes (MB)"
982 default 100 914 default 100
983 range 8 2048 915 range 8 2048
984 depends on STACK_GROWSUP && (!64BIT || 916 depends on STACK_GROWSUP && (!64BIT || COMPAT)
985 help 917 help
986 This is the maximum stack size in Me 918 This is the maximum stack size in Megabytes in the VM layout of 32-bit
987 user processes when the stack grows 919 user processes when the stack grows upwards (currently only on parisc
988 arch) when the RLIMIT_STACK hard lim 920 arch) when the RLIMIT_STACK hard limit is unlimited.
989 921
990 A sane initial value is 100 MB. 922 A sane initial value is 100 MB.
991 923
992 config DEFERRED_STRUCT_PAGE_INIT 924 config DEFERRED_STRUCT_PAGE_INIT
993 bool "Defer initialisation of struct p 925 bool "Defer initialisation of struct pages to kthreads"
994 depends on SPARSEMEM 926 depends on SPARSEMEM
995 depends on !NEED_PER_CPU_KM 927 depends on !NEED_PER_CPU_KM
996 depends on 64BIT 928 depends on 64BIT
997 depends on !KMSAN <<
998 select PADATA 929 select PADATA
999 help 930 help
1000 Ordinarily all struct pages are ini 931 Ordinarily all struct pages are initialised during early boot in a
1001 single thread. On very large machin 932 single thread. On very large machines this can take a considerable
1002 amount of time. If this option is s 933 amount of time. If this option is set, large machines will bring up
1003 a subset of memmap at boot and then 934 a subset of memmap at boot and then initialise the rest in parallel.
1004 This has a potential performance im 935 This has a potential performance impact on tasks running early in the
1005 lifetime of the system until these 936 lifetime of the system until these kthreads finish the
1006 initialisation. 937 initialisation.
1007 938
1008 config PAGE_IDLE_FLAG 939 config PAGE_IDLE_FLAG
1009 bool 940 bool
1010 select PAGE_EXTENSION if !64BIT 941 select PAGE_EXTENSION if !64BIT
1011 help 942 help
1012 This adds PG_idle and PG_young flag 943 This adds PG_idle and PG_young flags to 'struct page'. PTE Accessed
1013 bit writers can set the state of th 944 bit writers can set the state of the bit in the flags so that PTE
1014 Accessed bit readers may avoid dist 945 Accessed bit readers may avoid disturbance.
1015 946
1016 config IDLE_PAGE_TRACKING 947 config IDLE_PAGE_TRACKING
1017 bool "Enable idle page tracking" 948 bool "Enable idle page tracking"
1018 depends on SYSFS && MMU 949 depends on SYSFS && MMU
1019 select PAGE_IDLE_FLAG 950 select PAGE_IDLE_FLAG
1020 help 951 help
1021 This feature allows to estimate the 952 This feature allows to estimate the amount of user pages that have
1022 not been touched during a given per 953 not been touched during a given period of time. This information can
1023 be useful to tune memory cgroup lim 954 be useful to tune memory cgroup limits and/or for job placement
1024 within a compute cluster. 955 within a compute cluster.
1025 956
1026 See Documentation/admin-guide/mm/id 957 See Documentation/admin-guide/mm/idle_page_tracking.rst for
1027 more details. 958 more details.
1028 959
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 960 config ARCH_HAS_CACHE_LINE_SIZE
1036 bool 961 bool
1037 962
1038 config ARCH_HAS_CURRENT_STACK_POINTER 963 config ARCH_HAS_CURRENT_STACK_POINTER
1039 bool 964 bool
1040 help 965 help
1041 In support of HARDENED_USERCOPY per 966 In support of HARDENED_USERCOPY performing stack variable lifetime
1042 checking, an architecture-agnostic 967 checking, an architecture-agnostic way to find the stack pointer
1043 is needed. Once an architecture def 968 is needed. Once an architecture defines an unsigned long global
1044 register alias named "current_stack 969 register alias named "current_stack_pointer", this config can be
1045 selected. 970 selected.
1046 971
1047 config ARCH_HAS_PTE_DEVMAP 972 config ARCH_HAS_PTE_DEVMAP
1048 bool 973 bool
1049 974
1050 config ARCH_HAS_ZONE_DMA_SET 975 config ARCH_HAS_ZONE_DMA_SET
1051 bool 976 bool
1052 977
1053 config ZONE_DMA 978 config ZONE_DMA
1054 bool "Support DMA zone" if ARCH_HAS_Z 979 bool "Support DMA zone" if ARCH_HAS_ZONE_DMA_SET
1055 default y if ARM64 || X86 980 default y if ARM64 || X86
1056 981
1057 config ZONE_DMA32 982 config ZONE_DMA32
1058 bool "Support DMA32 zone" if ARCH_HAS 983 bool "Support DMA32 zone" if ARCH_HAS_ZONE_DMA_SET
1059 depends on !X86_32 984 depends on !X86_32
1060 default y if ARM64 985 default y if ARM64
1061 986
1062 config ZONE_DEVICE 987 config ZONE_DEVICE
1063 bool "Device memory (pmem, HMM, etc.. 988 bool "Device memory (pmem, HMM, etc...) hotplug support"
1064 depends on MEMORY_HOTPLUG 989 depends on MEMORY_HOTPLUG
1065 depends on MEMORY_HOTREMOVE 990 depends on MEMORY_HOTREMOVE
1066 depends on SPARSEMEM_VMEMMAP 991 depends on SPARSEMEM_VMEMMAP
1067 depends on ARCH_HAS_PTE_DEVMAP 992 depends on ARCH_HAS_PTE_DEVMAP
1068 select XARRAY_MULTI 993 select XARRAY_MULTI
1069 994
1070 help 995 help
1071 Device memory hotplug support allow 996 Device memory hotplug support allows for establishing pmem,
1072 or other device driver discovered m 997 or other device driver discovered memory regions, in the
1073 memmap. This allows pfn_to_page() l 998 memmap. This allows pfn_to_page() lookups of otherwise
1074 "device-physical" addresses which i 999 "device-physical" addresses which is needed for using a DAX
1075 mapping in an O_DIRECT operation, a 1000 mapping in an O_DIRECT operation, among other things.
1076 1001
1077 If FS_DAX is enabled, then say Y. 1002 If FS_DAX is enabled, then say Y.
1078 1003
1079 # 1004 #
1080 # Helpers to mirror range of the CPU page tab 1005 # Helpers to mirror range of the CPU page tables of a process into device page
1081 # tables. 1006 # tables.
1082 # 1007 #
1083 config HMM_MIRROR 1008 config HMM_MIRROR
1084 bool 1009 bool
1085 depends on MMU 1010 depends on MMU
1086 1011
1087 config GET_FREE_REGION 1012 config GET_FREE_REGION
>> 1013 depends on SPARSEMEM
1088 bool 1014 bool
1089 1015
1090 config DEVICE_PRIVATE 1016 config DEVICE_PRIVATE
1091 bool "Unaddressable device memory (GP 1017 bool "Unaddressable device memory (GPU memory, ...)"
1092 depends on ZONE_DEVICE 1018 depends on ZONE_DEVICE
1093 select GET_FREE_REGION 1019 select GET_FREE_REGION
1094 1020
1095 help 1021 help
1096 Allows creation of struct pages to 1022 Allows creation of struct pages to represent unaddressable device
1097 memory; i.e., memory that is only a 1023 memory; i.e., memory that is only accessible from the device (or
1098 group of devices). You likely also 1024 group of devices). You likely also want to select HMM_MIRROR.
1099 1025
1100 config VMAP_PFN 1026 config VMAP_PFN
1101 bool 1027 bool
1102 1028
1103 config ARCH_USES_HIGH_VMA_FLAGS 1029 config ARCH_USES_HIGH_VMA_FLAGS
1104 bool 1030 bool
1105 config ARCH_HAS_PKEYS 1031 config ARCH_HAS_PKEYS
1106 bool 1032 bool
1107 1033
1108 config ARCH_USES_PG_ARCH_2 !! 1034 config ARCH_USES_PG_ARCH_X
1109 bool <<
1110 config ARCH_USES_PG_ARCH_3 <<
1111 bool 1035 bool
>> 1036 help
>> 1037 Enable the definition of PG_arch_x page flags with x > 1. Only
>> 1038 suitable for 64-bit architectures with CONFIG_FLATMEM or
>> 1039 CONFIG_SPARSEMEM_VMEMMAP enabled, otherwise there may not be
>> 1040 enough room for additional bits in page->flags.
1112 1041
1113 config VM_EVENT_COUNTERS 1042 config VM_EVENT_COUNTERS
1114 default y 1043 default y
1115 bool "Enable VM event counters for /p 1044 bool "Enable VM event counters for /proc/vmstat" if EXPERT
1116 help 1045 help
1117 VM event counters are needed for ev 1046 VM event counters are needed for event counts to be shown.
1118 This option allows the disabling of 1047 This option allows the disabling of the VM event counters
1119 on EXPERT systems. /proc/vmstat wi 1048 on EXPERT systems. /proc/vmstat will only show page counts
1120 if VM event counters are disabled. 1049 if VM event counters are disabled.
1121 1050
1122 config PERCPU_STATS 1051 config PERCPU_STATS
1123 bool "Collect percpu memory statistic 1052 bool "Collect percpu memory statistics"
1124 help 1053 help
1125 This feature collects and exposes s 1054 This feature collects and exposes statistics via debugfs. The
1126 information includes global and per 1055 information includes global and per chunk statistics, which can
1127 be used to help understand percpu m 1056 be used to help understand percpu memory usage.
1128 1057
1129 config GUP_TEST 1058 config GUP_TEST
1130 bool "Enable infrastructure for get_u 1059 bool "Enable infrastructure for get_user_pages()-related unit tests"
1131 depends on DEBUG_FS 1060 depends on DEBUG_FS
1132 help 1061 help
1133 Provides /sys/kernel/debug/gup_test 1062 Provides /sys/kernel/debug/gup_test, which in turn provides a way
1134 to make ioctl calls that can launch 1063 to make ioctl calls that can launch kernel-based unit tests for
1135 the get_user_pages*() and pin_user_ 1064 the get_user_pages*() and pin_user_pages*() family of API calls.
1136 1065
1137 These tests include benchmark testi 1066 These tests include benchmark testing of the _fast variants of
1138 get_user_pages*() and pin_user_page 1067 get_user_pages*() and pin_user_pages*(), as well as smoke tests of
1139 the non-_fast variants. 1068 the non-_fast variants.
1140 1069
1141 There is also a sub-test that allow 1070 There is also a sub-test that allows running dump_page() on any
1142 of up to eight pages (selected by c 1071 of up to eight pages (selected by command line args) within the
1143 range of user-space addresses. Thes 1072 range of user-space addresses. These pages are either pinned via
1144 pin_user_pages*(), or pinned via ge 1073 pin_user_pages*(), or pinned via get_user_pages*(), as specified
1145 by other command line arguments. 1074 by other command line arguments.
1146 1075
1147 See tools/testing/selftests/mm/gup_ !! 1076 See tools/testing/selftests/vm/gup_test.c
1148 1077
1149 comment "GUP_TEST needs to have DEBUG_FS enab 1078 comment "GUP_TEST needs to have DEBUG_FS enabled"
1150 depends on !GUP_TEST && !DEBUG_FS 1079 depends on !GUP_TEST && !DEBUG_FS
1151 1080
1152 config GUP_GET_PXX_LOW_HIGH 1081 config GUP_GET_PXX_LOW_HIGH
1153 bool 1082 bool
1154 1083
1155 config DMAPOOL_TEST <<
1156 tristate "Enable a module to run time <<
1157 depends on HAS_DMA <<
1158 help <<
1159 Provides a test module that will al <<
1160 various sizes and report how long i <<
1161 provide a consistent way to measure <<
1162 dma_pool_alloc/free routines affect <<
1163 <<
1164 config ARCH_HAS_PTE_SPECIAL 1084 config ARCH_HAS_PTE_SPECIAL
1165 bool 1085 bool
1166 1086
>> 1087 #
>> 1088 # Some architectures require a special hugepage directory format that is
>> 1089 # required to support multiple hugepage sizes. For example a4fe3ce76
>> 1090 # "powerpc/mm: Allow more flexible layouts for hugepage pagetables"
>> 1091 # introduced it on powerpc. This allows for a more flexible hugepage
>> 1092 # pagetable layouts.
>> 1093 #
>> 1094 config ARCH_HAS_HUGEPD
>> 1095 bool
>> 1096
1167 config MAPPING_DIRTY_HELPERS 1097 config MAPPING_DIRTY_HELPERS
1168 bool 1098 bool
1169 1099
1170 config KMAP_LOCAL 1100 config KMAP_LOCAL
1171 bool 1101 bool
1172 1102
1173 config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY 1103 config KMAP_LOCAL_NON_LINEAR_PTE_ARRAY
1174 bool 1104 bool
1175 1105
1176 # struct io_mapping based helper. Selected b 1106 # struct io_mapping based helper. Selected by drivers that need them
1177 config IO_MAPPING 1107 config IO_MAPPING
1178 bool 1108 bool
1179 1109
1180 config MEMFD_CREATE <<
1181 bool "Enable memfd_create() system ca <<
1182 <<
1183 config SECRETMEM 1110 config SECRETMEM
1184 default y 1111 default y
1185 bool "Enable memfd_secret() system ca 1112 bool "Enable memfd_secret() system call" if EXPERT
1186 depends on ARCH_HAS_SET_DIRECT_MAP 1113 depends on ARCH_HAS_SET_DIRECT_MAP
1187 help 1114 help
1188 Enable the memfd_secret() system ca 1115 Enable the memfd_secret() system call with the ability to create
1189 memory areas visible only in the co 1116 memory areas visible only in the context of the owning process and
1190 not mapped to other processes and o 1117 not mapped to other processes and other kernel page tables.
1191 1118
1192 config ANON_VMA_NAME 1119 config ANON_VMA_NAME
1193 bool "Anonymous VMA name support" 1120 bool "Anonymous VMA name support"
1194 depends on PROC_FS && ADVISE_SYSCALLS 1121 depends on PROC_FS && ADVISE_SYSCALLS && MMU
1195 1122
1196 help 1123 help
1197 Allow naming anonymous virtual memo 1124 Allow naming anonymous virtual memory areas.
1198 1125
1199 This feature allows assigning names 1126 This feature allows assigning names to virtual memory areas. Assigned
1200 names can be later retrieved from / 1127 names can be later retrieved from /proc/pid/maps and /proc/pid/smaps
1201 and help identifying individual ano 1128 and help identifying individual anonymous memory areas.
1202 Assigning a name to anonymous virtu 1129 Assigning a name to anonymous virtual memory area might prevent that
1203 area from being merged with adjacen 1130 area from being merged with adjacent virtual memory areas due to the
1204 difference in their name. 1131 difference in their name.
1205 1132
>> 1133 config USERFAULTFD
>> 1134 bool "Enable userfaultfd() system call"
>> 1135 depends on MMU
>> 1136 help
>> 1137 Enable the userfaultfd() system call that allows to intercept and
>> 1138 handle page faults in userland.
>> 1139
1206 config HAVE_ARCH_USERFAULTFD_WP 1140 config HAVE_ARCH_USERFAULTFD_WP
1207 bool 1141 bool
1208 help 1142 help
1209 Arch has userfaultfd write protecti 1143 Arch has userfaultfd write protection support
1210 1144
1211 config HAVE_ARCH_USERFAULTFD_MINOR 1145 config HAVE_ARCH_USERFAULTFD_MINOR
1212 bool 1146 bool
1213 help 1147 help
1214 Arch has userfaultfd minor fault su 1148 Arch has userfaultfd minor fault support
1215 1149
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 1150 config PTE_MARKER_UFFD_WP
1225 bool "Userfaultfd write protection su 1151 bool "Userfaultfd write protection support for shmem/hugetlbfs"
1226 default y 1152 default y
1227 depends on HAVE_ARCH_USERFAULTFD_WP 1153 depends on HAVE_ARCH_USERFAULTFD_WP
1228 1154
1229 help 1155 help
1230 Allows to create marker PTEs for us 1156 Allows to create marker PTEs for userfaultfd write protection
1231 purposes. It is required to enable 1157 purposes. It is required to enable userfaultfd write protection on
1232 file-backed memory types like shmem 1158 file-backed memory types like shmem and hugetlbfs.
1233 endif # USERFAULTFD <<
1234 1159
1235 # multi-gen LRU { 1160 # multi-gen LRU {
1236 config LRU_GEN 1161 config LRU_GEN
1237 bool "Multi-Gen LRU" 1162 bool "Multi-Gen LRU"
1238 depends on MMU 1163 depends on MMU
1239 # make sure folio->flags has enough s 1164 # make sure folio->flags has enough spare bits
1240 depends on 64BIT || !SPARSEMEM || SPA 1165 depends on 64BIT || !SPARSEMEM || SPARSEMEM_VMEMMAP
1241 help 1166 help
1242 A high performance LRU implementati 1167 A high performance LRU implementation to overcommit memory. See
1243 Documentation/admin-guide/mm/multig 1168 Documentation/admin-guide/mm/multigen_lru.rst for details.
1244 1169
1245 config LRU_GEN_ENABLED 1170 config LRU_GEN_ENABLED
1246 bool "Enable by default" 1171 bool "Enable by default"
1247 depends on LRU_GEN 1172 depends on LRU_GEN
1248 help 1173 help
1249 This option enables the multi-gen L 1174 This option enables the multi-gen LRU by default.
1250 1175
1251 config LRU_GEN_STATS 1176 config LRU_GEN_STATS
1252 bool "Full stats for debugging" 1177 bool "Full stats for debugging"
1253 depends on LRU_GEN 1178 depends on LRU_GEN
1254 help 1179 help
1255 Do not enable this option unless yo 1180 Do not enable this option unless you plan to look at historical stats
1256 from evicted generations for debugg 1181 from evicted generations for debugging purpose.
1257 1182
1258 This option has a per-memcg and per 1183 This option has a per-memcg and per-node memory overhead.
1259 <<
1260 config LRU_GEN_WALKS_MMU <<
1261 def_bool y <<
1262 depends on LRU_GEN && ARCH_HAS_HW_PTE <<
1263 # } 1184 # }
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 1185
1298 source "mm/damon/Kconfig" 1186 source "mm/damon/Kconfig"
1299 1187
1300 endmenu 1188 endmenu
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