| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| 2 | #ifndef __LINUX_GFP_TYPES_H |
| 3 | #define __LINUX_GFP_TYPES_H |
| 4 | |
| 5 | /* The typedef is in types.h but we want the documentation here */ |
| 6 | #if 0 |
| 7 | /** |
| 8 | * typedef gfp_t - Memory allocation flags. |
| 9 | * |
| 10 | * GFP flags are commonly used throughout Linux to indicate how memory |
| 11 | * should be allocated. The GFP acronym stands for get_free_pages(), |
| 12 | * the underlying memory allocation function. Not every GFP flag is |
| 13 | * supported by every function which may allocate memory. Most users |
| 14 | * will want to use a plain ``GFP_KERNEL``. |
| 15 | */ |
| 16 | typedef unsigned int __bitwise gfp_t; |
| 17 | #endif |
| 18 | |
| 19 | /* |
| 20 | * In case of changes, please don't forget to update |
| 21 | * include/trace/events/mmflags.h and tools/perf/builtin-kmem.c |
| 22 | */ |
| 23 | |
| 24 | enum { |
| 25 | ___GFP_DMA_BIT, |
| 26 | ___GFP_HIGHMEM_BIT, |
| 27 | ___GFP_DMA32_BIT, |
| 28 | ___GFP_MOVABLE_BIT, |
| 29 | ___GFP_RECLAIMABLE_BIT, |
| 30 | ___GFP_HIGH_BIT, |
| 31 | ___GFP_IO_BIT, |
| 32 | ___GFP_FS_BIT, |
| 33 | ___GFP_ZERO_BIT, |
| 34 | ___GFP_UNUSED_BIT, /* 0x200u unused */ |
| 35 | ___GFP_DIRECT_RECLAIM_BIT, |
| 36 | ___GFP_KSWAPD_RECLAIM_BIT, |
| 37 | ___GFP_WRITE_BIT, |
| 38 | ___GFP_NOWARN_BIT, |
| 39 | ___GFP_RETRY_MAYFAIL_BIT, |
| 40 | ___GFP_NOFAIL_BIT, |
| 41 | ___GFP_NORETRY_BIT, |
| 42 | ___GFP_MEMALLOC_BIT, |
| 43 | ___GFP_COMP_BIT, |
| 44 | ___GFP_NOMEMALLOC_BIT, |
| 45 | ___GFP_HARDWALL_BIT, |
| 46 | ___GFP_THISNODE_BIT, |
| 47 | ___GFP_ACCOUNT_BIT, |
| 48 | ___GFP_ZEROTAGS_BIT, |
| 49 | #ifdef CONFIG_KASAN_HW_TAGS |
| 50 | ___GFP_SKIP_ZERO_BIT, |
| 51 | ___GFP_SKIP_KASAN_BIT, |
| 52 | #endif |
| 53 | #ifdef CONFIG_LOCKDEP |
| 54 | ___GFP_NOLOCKDEP_BIT, |
| 55 | #endif |
| 56 | ___GFP_LAST_BIT |
| 57 | }; |
| 58 | |
| 59 | /* Plain integer GFP bitmasks. Do not use this directly. */ |
| 60 | #define ___GFP_DMA BIT(___GFP_DMA_BIT) |
| 61 | #define ___GFP_HIGHMEM BIT(___GFP_HIGHMEM_BIT) |
| 62 | #define ___GFP_DMA32 BIT(___GFP_DMA32_BIT) |
| 63 | #define ___GFP_MOVABLE BIT(___GFP_MOVABLE_BIT) |
| 64 | #define ___GFP_RECLAIMABLE BIT(___GFP_RECLAIMABLE_BIT) |
| 65 | #define ___GFP_HIGH BIT(___GFP_HIGH_BIT) |
| 66 | #define ___GFP_IO BIT(___GFP_IO_BIT) |
| 67 | #define ___GFP_FS BIT(___GFP_FS_BIT) |
| 68 | #define ___GFP_ZERO BIT(___GFP_ZERO_BIT) |
| 69 | /* 0x200u unused */ |
| 70 | #define ___GFP_DIRECT_RECLAIM BIT(___GFP_DIRECT_RECLAIM_BIT) |
| 71 | #define ___GFP_KSWAPD_RECLAIM BIT(___GFP_KSWAPD_RECLAIM_BIT) |
| 72 | #define ___GFP_WRITE BIT(___GFP_WRITE_BIT) |
| 73 | #define ___GFP_NOWARN BIT(___GFP_NOWARN_BIT) |
| 74 | #define ___GFP_RETRY_MAYFAIL BIT(___GFP_RETRY_MAYFAIL_BIT) |
| 75 | #define ___GFP_NOFAIL BIT(___GFP_NOFAIL_BIT) |
| 76 | #define ___GFP_NORETRY BIT(___GFP_NORETRY_BIT) |
| 77 | #define ___GFP_MEMALLOC BIT(___GFP_MEMALLOC_BIT) |
| 78 | #define ___GFP_COMP BIT(___GFP_COMP_BIT) |
| 79 | #define ___GFP_NOMEMALLOC BIT(___GFP_NOMEMALLOC_BIT) |
| 80 | #define ___GFP_HARDWALL BIT(___GFP_HARDWALL_BIT) |
| 81 | #define ___GFP_THISNODE BIT(___GFP_THISNODE_BIT) |
| 82 | #define ___GFP_ACCOUNT BIT(___GFP_ACCOUNT_BIT) |
| 83 | #define ___GFP_ZEROTAGS BIT(___GFP_ZEROTAGS_BIT) |
| 84 | #ifdef CONFIG_KASAN_HW_TAGS |
| 85 | #define ___GFP_SKIP_ZERO BIT(___GFP_SKIP_ZERO_BIT) |
| 86 | #define ___GFP_SKIP_KASAN BIT(___GFP_SKIP_KASAN_BIT) |
| 87 | #else |
| 88 | #define ___GFP_SKIP_ZERO 0 |
| 89 | #define ___GFP_SKIP_KASAN 0 |
| 90 | #endif |
| 91 | #ifdef CONFIG_LOCKDEP |
| 92 | #define ___GFP_NOLOCKDEP BIT(___GFP_NOLOCKDEP_BIT) |
| 93 | #else |
| 94 | #define ___GFP_NOLOCKDEP 0 |
| 95 | #endif |
| 96 | |
| 97 | /* |
| 98 | * Physical address zone modifiers (see linux/mmzone.h - low four bits) |
| 99 | * |
| 100 | * Do not put any conditional on these. If necessary modify the definitions |
| 101 | * without the underscores and use them consistently. The definitions here may |
| 102 | * be used in bit comparisons. |
| 103 | */ |
| 104 | #define __GFP_DMA ((__force gfp_t)___GFP_DMA) |
| 105 | #define __GFP_HIGHMEM ((__force gfp_t)___GFP_HIGHMEM) |
| 106 | #define __GFP_DMA32 ((__force gfp_t)___GFP_DMA32) |
| 107 | #define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* ZONE_MOVABLE allowed */ |
| 108 | #define GFP_ZONEMASK (__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE) |
| 109 | |
| 110 | /** |
| 111 | * DOC: Page mobility and placement hints |
| 112 | * |
| 113 | * Page mobility and placement hints |
| 114 | * --------------------------------- |
| 115 | * |
| 116 | * These flags provide hints about how mobile the page is. Pages with similar |
| 117 | * mobility are placed within the same pageblocks to minimise problems due |
| 118 | * to external fragmentation. |
| 119 | * |
| 120 | * %__GFP_MOVABLE (also a zone modifier) indicates that the page can be |
| 121 | * moved by page migration during memory compaction or can be reclaimed. |
| 122 | * |
| 123 | * %__GFP_RECLAIMABLE is used for slab allocations that specify |
| 124 | * SLAB_RECLAIM_ACCOUNT and whose pages can be freed via shrinkers. |
| 125 | * |
| 126 | * %__GFP_WRITE indicates the caller intends to dirty the page. Where possible, |
| 127 | * these pages will be spread between local zones to avoid all the dirty |
| 128 | * pages being in one zone (fair zone allocation policy). |
| 129 | * |
| 130 | * %__GFP_HARDWALL enforces the cpuset memory allocation policy. |
| 131 | * |
| 132 | * %__GFP_THISNODE forces the allocation to be satisfied from the requested |
| 133 | * node with no fallbacks or placement policy enforcements. |
| 134 | * |
| 135 | * %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg. |
| 136 | */ |
| 137 | #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE) |
| 138 | #define __GFP_WRITE ((__force gfp_t)___GFP_WRITE) |
| 139 | #define __GFP_HARDWALL ((__force gfp_t)___GFP_HARDWALL) |
| 140 | #define __GFP_THISNODE ((__force gfp_t)___GFP_THISNODE) |
| 141 | #define __GFP_ACCOUNT ((__force gfp_t)___GFP_ACCOUNT) |
| 142 | |
| 143 | /** |
| 144 | * DOC: Watermark modifiers |
| 145 | * |
| 146 | * Watermark modifiers -- controls access to emergency reserves |
| 147 | * ------------------------------------------------------------ |
| 148 | * |
| 149 | * %__GFP_HIGH indicates that the caller is high-priority and that granting |
| 150 | * the request is necessary before the system can make forward progress. |
| 151 | * For example creating an IO context to clean pages and requests |
| 152 | * from atomic context. |
| 153 | * |
| 154 | * %__GFP_MEMALLOC allows access to all memory. This should only be used when |
| 155 | * the caller guarantees the allocation will allow more memory to be freed |
| 156 | * very shortly e.g. process exiting or swapping. Users either should |
| 157 | * be the MM or co-ordinating closely with the VM (e.g. swap over NFS). |
| 158 | * Users of this flag have to be extremely careful to not deplete the reserve |
| 159 | * completely and implement a throttling mechanism which controls the |
| 160 | * consumption of the reserve based on the amount of freed memory. |
| 161 | * Usage of a pre-allocated pool (e.g. mempool) should be always considered |
| 162 | * before using this flag. |
| 163 | * |
| 164 | * %__GFP_NOMEMALLOC is used to explicitly forbid access to emergency reserves. |
| 165 | * This takes precedence over the %__GFP_MEMALLOC flag if both are set. |
| 166 | */ |
| 167 | #define __GFP_HIGH ((__force gfp_t)___GFP_HIGH) |
| 168 | #define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC) |
| 169 | #define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) |
| 170 | |
| 171 | /** |
| 172 | * DOC: Reclaim modifiers |
| 173 | * |
| 174 | * Reclaim modifiers |
| 175 | * ----------------- |
| 176 | * Please note that all the following flags are only applicable to sleepable |
| 177 | * allocations (e.g. %GFP_NOWAIT and %GFP_ATOMIC will ignore them). |
| 178 | * |
| 179 | * %__GFP_IO can start physical IO. |
| 180 | * |
| 181 | * %__GFP_FS can call down to the low-level FS. Clearing the flag avoids the |
| 182 | * allocator recursing into the filesystem which might already be holding |
| 183 | * locks. |
| 184 | * |
| 185 | * %__GFP_DIRECT_RECLAIM indicates that the caller may enter direct reclaim. |
| 186 | * This flag can be cleared to avoid unnecessary delays when a fallback |
| 187 | * option is available. |
| 188 | * |
| 189 | * %__GFP_KSWAPD_RECLAIM indicates that the caller wants to wake kswapd when |
| 190 | * the low watermark is reached and have it reclaim pages until the high |
| 191 | * watermark is reached. A caller may wish to clear this flag when fallback |
| 192 | * options are available and the reclaim is likely to disrupt the system. The |
| 193 | * canonical example is THP allocation where a fallback is cheap but |
| 194 | * reclaim/compaction may cause indirect stalls. |
| 195 | * |
| 196 | * %__GFP_RECLAIM is shorthand to allow/forbid both direct and kswapd reclaim. |
| 197 | * |
| 198 | * The default allocator behavior depends on the request size. We have a concept |
| 199 | * of so-called costly allocations (with order > %PAGE_ALLOC_COSTLY_ORDER). |
| 200 | * !costly allocations are too essential to fail so they are implicitly |
| 201 | * non-failing by default (with some exceptions like OOM victims might fail so |
| 202 | * the caller still has to check for failures) while costly requests try to be |
| 203 | * not disruptive and back off even without invoking the OOM killer. |
| 204 | * The following three modifiers might be used to override some of these |
| 205 | * implicit rules. |
| 206 | * |
| 207 | * %__GFP_NORETRY: The VM implementation will try only very lightweight |
| 208 | * memory direct reclaim to get some memory under memory pressure (thus |
| 209 | * it can sleep). It will avoid disruptive actions like OOM killer. The |
| 210 | * caller must handle the failure which is quite likely to happen under |
| 211 | * heavy memory pressure. The flag is suitable when failure can easily be |
| 212 | * handled at small cost, such as reduced throughput. |
| 213 | * |
| 214 | * %__GFP_RETRY_MAYFAIL: The VM implementation will retry memory reclaim |
| 215 | * procedures that have previously failed if there is some indication |
| 216 | * that progress has been made elsewhere. It can wait for other |
| 217 | * tasks to attempt high-level approaches to freeing memory such as |
| 218 | * compaction (which removes fragmentation) and page-out. |
| 219 | * There is still a definite limit to the number of retries, but it is |
| 220 | * a larger limit than with %__GFP_NORETRY. |
| 221 | * Allocations with this flag may fail, but only when there is |
| 222 | * genuinely little unused memory. While these allocations do not |
| 223 | * directly trigger the OOM killer, their failure indicates that |
| 224 | * the system is likely to need to use the OOM killer soon. The |
| 225 | * caller must handle failure, but can reasonably do so by failing |
| 226 | * a higher-level request, or completing it only in a much less |
| 227 | * efficient manner. |
| 228 | * If the allocation does fail, and the caller is in a position to |
| 229 | * free some non-essential memory, doing so could benefit the system |
| 230 | * as a whole. |
| 231 | * |
| 232 | * %__GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller |
| 233 | * cannot handle allocation failures. The allocation could block |
| 234 | * indefinitely but will never return with failure. Testing for |
| 235 | * failure is pointless. |
| 236 | * New users should be evaluated carefully (and the flag should be |
| 237 | * used only when there is no reasonable failure policy) but it is |
| 238 | * definitely preferable to use the flag rather than opencode endless |
| 239 | * loop around allocator. |
| 240 | * Using this flag for costly allocations is _highly_ discouraged. |
| 241 | */ |
| 242 | #define __GFP_IO ((__force gfp_t)___GFP_IO) |
| 243 | #define __GFP_FS ((__force gfp_t)___GFP_FS) |
| 244 | #define __GFP_DIRECT_RECLAIM ((__force gfp_t)___GFP_DIRECT_RECLAIM) /* Caller can reclaim */ |
| 245 | #define __GFP_KSWAPD_RECLAIM ((__force gfp_t)___GFP_KSWAPD_RECLAIM) /* kswapd can wake */ |
| 246 | #define __GFP_RECLAIM ((__force gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM)) |
| 247 | #define __GFP_RETRY_MAYFAIL ((__force gfp_t)___GFP_RETRY_MAYFAIL) |
| 248 | #define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) |
| 249 | #define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) |
| 250 | |
| 251 | /** |
| 252 | * DOC: Action modifiers |
| 253 | * |
| 254 | * Action modifiers |
| 255 | * ---------------- |
| 256 | * |
| 257 | * %__GFP_NOWARN suppresses allocation failure reports. |
| 258 | * |
| 259 | * %__GFP_COMP address compound page metadata. |
| 260 | * |
| 261 | * %__GFP_ZERO returns a zeroed page on success. |
| 262 | * |
| 263 | * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself |
| 264 | * is being zeroed (either via __GFP_ZERO or via init_on_alloc, provided that |
| 265 | * __GFP_SKIP_ZERO is not set). This flag is intended for optimization: setting |
| 266 | * memory tags at the same time as zeroing memory has minimal additional |
| 267 | * performance impact. |
| 268 | * |
| 269 | * %__GFP_SKIP_KASAN makes KASAN skip unpoisoning on page allocation. |
| 270 | * Used for userspace and vmalloc pages; the latter are unpoisoned by |
| 271 | * kasan_unpoison_vmalloc instead. For userspace pages, results in |
| 272 | * poisoning being skipped as well, see should_skip_kasan_poison for |
| 273 | * details. Only effective in HW_TAGS mode. |
| 274 | */ |
| 275 | #define __GFP_NOWARN ((__force gfp_t)___GFP_NOWARN) |
| 276 | #define __GFP_COMP ((__force gfp_t)___GFP_COMP) |
| 277 | #define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) |
| 278 | #define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS) |
| 279 | #define __GFP_SKIP_ZERO ((__force gfp_t)___GFP_SKIP_ZERO) |
| 280 | #define __GFP_SKIP_KASAN ((__force gfp_t)___GFP_SKIP_KASAN) |
| 281 | |
| 282 | /* Disable lockdep for GFP context tracking */ |
| 283 | #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) |
| 284 | |
| 285 | /* Room for N __GFP_FOO bits */ |
| 286 | #define __GFP_BITS_SHIFT ___GFP_LAST_BIT |
| 287 | #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) |
| 288 | |
| 289 | /** |
| 290 | * DOC: Useful GFP flag combinations |
| 291 | * |
| 292 | * Useful GFP flag combinations |
| 293 | * ---------------------------- |
| 294 | * |
| 295 | * Useful GFP flag combinations that are commonly used. It is recommended |
| 296 | * that subsystems start with one of these combinations and then set/clear |
| 297 | * %__GFP_FOO flags as necessary. |
| 298 | * |
| 299 | * %GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower |
| 300 | * watermark is applied to allow access to "atomic reserves". |
| 301 | * The current implementation doesn't support NMI and few other strict |
| 302 | * non-preemptive contexts (e.g. raw_spin_lock). The same applies to %GFP_NOWAIT. |
| 303 | * |
| 304 | * %GFP_KERNEL is typical for kernel-internal allocations. The caller requires |
| 305 | * %ZONE_NORMAL or a lower zone for direct access but can direct reclaim. |
| 306 | * |
| 307 | * %GFP_KERNEL_ACCOUNT is the same as GFP_KERNEL, except the allocation is |
| 308 | * accounted to kmemcg. |
| 309 | * |
| 310 | * %GFP_NOWAIT is for kernel allocations that should not stall for direct |
| 311 | * reclaim, start physical IO or use any filesystem callback. It is very |
| 312 | * likely to fail to allocate memory, even for very small allocations. |
| 313 | * |
| 314 | * %GFP_NOIO will use direct reclaim to discard clean pages or slab pages |
| 315 | * that do not require the starting of any physical IO. |
| 316 | * Please try to avoid using this flag directly and instead use |
| 317 | * memalloc_noio_{save,restore} to mark the whole scope which cannot |
| 318 | * perform any IO with a short explanation why. All allocation requests |
| 319 | * will inherit GFP_NOIO implicitly. |
| 320 | * |
| 321 | * %GFP_NOFS will use direct reclaim but will not use any filesystem interfaces. |
| 322 | * Please try to avoid using this flag directly and instead use |
| 323 | * memalloc_nofs_{save,restore} to mark the whole scope which cannot/shouldn't |
| 324 | * recurse into the FS layer with a short explanation why. All allocation |
| 325 | * requests will inherit GFP_NOFS implicitly. |
| 326 | * |
| 327 | * %GFP_USER is for userspace allocations that also need to be directly |
| 328 | * accessibly by the kernel or hardware. It is typically used by hardware |
| 329 | * for buffers that are mapped to userspace (e.g. graphics) that hardware |
| 330 | * still must DMA to. cpuset limits are enforced for these allocations. |
| 331 | * |
| 332 | * %GFP_DMA exists for historical reasons and should be avoided where possible. |
| 333 | * The flags indicates that the caller requires that the lowest zone be |
| 334 | * used (%ZONE_DMA or 16M on x86-64). Ideally, this would be removed but |
| 335 | * it would require careful auditing as some users really require it and |
| 336 | * others use the flag to avoid lowmem reserves in %ZONE_DMA and treat the |
| 337 | * lowest zone as a type of emergency reserve. |
| 338 | * |
| 339 | * %GFP_DMA32 is similar to %GFP_DMA except that the caller requires a 32-bit |
| 340 | * address. Note that kmalloc(..., GFP_DMA32) does not return DMA32 memory |
| 341 | * because the DMA32 kmalloc cache array is not implemented. |
| 342 | * (Reason: there is no such user in kernel). |
| 343 | * |
| 344 | * %GFP_HIGHUSER is for userspace allocations that may be mapped to userspace, |
| 345 | * do not need to be directly accessible by the kernel but that cannot |
| 346 | * move once in use. An example may be a hardware allocation that maps |
| 347 | * data directly into userspace but has no addressing limitations. |
| 348 | * |
| 349 | * %GFP_HIGHUSER_MOVABLE is for userspace allocations that the kernel does not |
| 350 | * need direct access to but can use kmap() when access is required. They |
| 351 | * are expected to be movable via page reclaim or page migration. Typically, |
| 352 | * pages on the LRU would also be allocated with %GFP_HIGHUSER_MOVABLE. |
| 353 | * |
| 354 | * %GFP_TRANSHUGE and %GFP_TRANSHUGE_LIGHT are used for THP allocations. They |
| 355 | * are compound allocations that will generally fail quickly if memory is not |
| 356 | * available and will not wake kswapd/kcompactd on failure. The _LIGHT |
| 357 | * version does not attempt reclaim/compaction at all and is by default used |
| 358 | * in page fault path, while the non-light is used by khugepaged. |
| 359 | */ |
| 360 | #define GFP_ATOMIC (__GFP_HIGH|__GFP_KSWAPD_RECLAIM) |
| 361 | #define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS) |
| 362 | #define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT) |
| 363 | #define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM | __GFP_NOWARN) |
| 364 | #define GFP_NOIO (__GFP_RECLAIM) |
| 365 | #define GFP_NOFS (__GFP_RECLAIM | __GFP_IO) |
| 366 | #define GFP_USER (__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL) |
| 367 | #define GFP_DMA __GFP_DMA |
| 368 | #define GFP_DMA32 __GFP_DMA32 |
| 369 | #define GFP_HIGHUSER (GFP_USER | __GFP_HIGHMEM) |
| 370 | #define GFP_HIGHUSER_MOVABLE (GFP_HIGHUSER | __GFP_MOVABLE | __GFP_SKIP_KASAN) |
| 371 | #define GFP_TRANSHUGE_LIGHT ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ |
| 372 | __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM) |
| 373 | #define GFP_TRANSHUGE (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM) |
| 374 | |
| 375 | #endif /* __LINUX_GFP_TYPES_H */ |