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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 | /* Plain integer GFP bitmasks. Do not use this directly. */ | |
25 | #define ___GFP_DMA 0x01u | |
26 | #define ___GFP_HIGHMEM 0x02u | |
27 | #define ___GFP_DMA32 0x04u | |
28 | #define ___GFP_MOVABLE 0x08u | |
29 | #define ___GFP_RECLAIMABLE 0x10u | |
30 | #define ___GFP_HIGH 0x20u | |
31 | #define ___GFP_IO 0x40u | |
32 | #define ___GFP_FS 0x80u | |
33 | #define ___GFP_ZERO 0x100u | |
2973d822 | 34 | /* 0x200u unused */ |
cb5a065b IM |
35 | #define ___GFP_DIRECT_RECLAIM 0x400u |
36 | #define ___GFP_KSWAPD_RECLAIM 0x800u | |
37 | #define ___GFP_WRITE 0x1000u | |
38 | #define ___GFP_NOWARN 0x2000u | |
39 | #define ___GFP_RETRY_MAYFAIL 0x4000u | |
40 | #define ___GFP_NOFAIL 0x8000u | |
41 | #define ___GFP_NORETRY 0x10000u | |
42 | #define ___GFP_MEMALLOC 0x20000u | |
43 | #define ___GFP_COMP 0x40000u | |
44 | #define ___GFP_NOMEMALLOC 0x80000u | |
45 | #define ___GFP_HARDWALL 0x100000u | |
46 | #define ___GFP_THISNODE 0x200000u | |
47 | #define ___GFP_ACCOUNT 0x400000u | |
48 | #define ___GFP_ZEROTAGS 0x800000u | |
49 | #ifdef CONFIG_KASAN_HW_TAGS | |
0a54864f PC |
50 | #define ___GFP_SKIP_ZERO 0x1000000u |
51 | #define ___GFP_SKIP_KASAN 0x2000000u | |
cb5a065b | 52 | #else |
0a54864f PC |
53 | #define ___GFP_SKIP_ZERO 0 |
54 | #define ___GFP_SKIP_KASAN 0 | |
cb5a065b IM |
55 | #endif |
56 | #ifdef CONFIG_LOCKDEP | |
0a54864f | 57 | #define ___GFP_NOLOCKDEP 0x4000000u |
cb5a065b IM |
58 | #else |
59 | #define ___GFP_NOLOCKDEP 0 | |
60 | #endif | |
61 | /* If the above are modified, __GFP_BITS_SHIFT may need updating */ | |
62 | ||
63 | /* | |
64 | * Physical address zone modifiers (see linux/mmzone.h - low four bits) | |
65 | * | |
66 | * Do not put any conditional on these. If necessary modify the definitions | |
67 | * without the underscores and use them consistently. The definitions here may | |
68 | * be used in bit comparisons. | |
69 | */ | |
70 | #define __GFP_DMA ((__force gfp_t)___GFP_DMA) | |
71 | #define __GFP_HIGHMEM ((__force gfp_t)___GFP_HIGHMEM) | |
72 | #define __GFP_DMA32 ((__force gfp_t)___GFP_DMA32) | |
73 | #define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* ZONE_MOVABLE allowed */ | |
74 | #define GFP_ZONEMASK (__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE) | |
75 | ||
76 | /** | |
77 | * DOC: Page mobility and placement hints | |
78 | * | |
79 | * Page mobility and placement hints | |
80 | * --------------------------------- | |
81 | * | |
82 | * These flags provide hints about how mobile the page is. Pages with similar | |
83 | * mobility are placed within the same pageblocks to minimise problems due | |
84 | * to external fragmentation. | |
85 | * | |
86 | * %__GFP_MOVABLE (also a zone modifier) indicates that the page can be | |
87 | * moved by page migration during memory compaction or can be reclaimed. | |
88 | * | |
89 | * %__GFP_RECLAIMABLE is used for slab allocations that specify | |
90 | * SLAB_RECLAIM_ACCOUNT and whose pages can be freed via shrinkers. | |
91 | * | |
92 | * %__GFP_WRITE indicates the caller intends to dirty the page. Where possible, | |
93 | * these pages will be spread between local zones to avoid all the dirty | |
94 | * pages being in one zone (fair zone allocation policy). | |
95 | * | |
96 | * %__GFP_HARDWALL enforces the cpuset memory allocation policy. | |
97 | * | |
98 | * %__GFP_THISNODE forces the allocation to be satisfied from the requested | |
99 | * node with no fallbacks or placement policy enforcements. | |
100 | * | |
101 | * %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg. | |
102 | */ | |
103 | #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE) | |
104 | #define __GFP_WRITE ((__force gfp_t)___GFP_WRITE) | |
105 | #define __GFP_HARDWALL ((__force gfp_t)___GFP_HARDWALL) | |
106 | #define __GFP_THISNODE ((__force gfp_t)___GFP_THISNODE) | |
107 | #define __GFP_ACCOUNT ((__force gfp_t)___GFP_ACCOUNT) | |
108 | ||
109 | /** | |
110 | * DOC: Watermark modifiers | |
111 | * | |
112 | * Watermark modifiers -- controls access to emergency reserves | |
113 | * ------------------------------------------------------------ | |
114 | * | |
115 | * %__GFP_HIGH indicates that the caller is high-priority and that granting | |
116 | * the request is necessary before the system can make forward progress. | |
2973d822 N |
117 | * For example creating an IO context to clean pages and requests |
118 | * from atomic context. | |
cb5a065b IM |
119 | * |
120 | * %__GFP_MEMALLOC allows access to all memory. This should only be used when | |
121 | * the caller guarantees the allocation will allow more memory to be freed | |
122 | * very shortly e.g. process exiting or swapping. Users either should | |
123 | * be the MM or co-ordinating closely with the VM (e.g. swap over NFS). | |
124 | * Users of this flag have to be extremely careful to not deplete the reserve | |
125 | * completely and implement a throttling mechanism which controls the | |
126 | * consumption of the reserve based on the amount of freed memory. | |
127 | * Usage of a pre-allocated pool (e.g. mempool) should be always considered | |
128 | * before using this flag. | |
129 | * | |
130 | * %__GFP_NOMEMALLOC is used to explicitly forbid access to emergency reserves. | |
131 | * This takes precedence over the %__GFP_MEMALLOC flag if both are set. | |
132 | */ | |
cb5a065b IM |
133 | #define __GFP_HIGH ((__force gfp_t)___GFP_HIGH) |
134 | #define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC) | |
135 | #define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) | |
136 | ||
137 | /** | |
138 | * DOC: Reclaim modifiers | |
139 | * | |
140 | * Reclaim modifiers | |
141 | * ----------------- | |
142 | * Please note that all the following flags are only applicable to sleepable | |
143 | * allocations (e.g. %GFP_NOWAIT and %GFP_ATOMIC will ignore them). | |
144 | * | |
145 | * %__GFP_IO can start physical IO. | |
146 | * | |
147 | * %__GFP_FS can call down to the low-level FS. Clearing the flag avoids the | |
148 | * allocator recursing into the filesystem which might already be holding | |
149 | * locks. | |
150 | * | |
151 | * %__GFP_DIRECT_RECLAIM indicates that the caller may enter direct reclaim. | |
152 | * This flag can be cleared to avoid unnecessary delays when a fallback | |
153 | * option is available. | |
154 | * | |
155 | * %__GFP_KSWAPD_RECLAIM indicates that the caller wants to wake kswapd when | |
156 | * the low watermark is reached and have it reclaim pages until the high | |
157 | * watermark is reached. A caller may wish to clear this flag when fallback | |
158 | * options are available and the reclaim is likely to disrupt the system. The | |
159 | * canonical example is THP allocation where a fallback is cheap but | |
160 | * reclaim/compaction may cause indirect stalls. | |
161 | * | |
162 | * %__GFP_RECLAIM is shorthand to allow/forbid both direct and kswapd reclaim. | |
163 | * | |
164 | * The default allocator behavior depends on the request size. We have a concept | |
165 | * of so called costly allocations (with order > %PAGE_ALLOC_COSTLY_ORDER). | |
166 | * !costly allocations are too essential to fail so they are implicitly | |
167 | * non-failing by default (with some exceptions like OOM victims might fail so | |
168 | * the caller still has to check for failures) while costly requests try to be | |
169 | * not disruptive and back off even without invoking the OOM killer. | |
170 | * The following three modifiers might be used to override some of these | |
171 | * implicit rules | |
172 | * | |
173 | * %__GFP_NORETRY: The VM implementation will try only very lightweight | |
174 | * memory direct reclaim to get some memory under memory pressure (thus | |
175 | * it can sleep). It will avoid disruptive actions like OOM killer. The | |
176 | * caller must handle the failure which is quite likely to happen under | |
177 | * heavy memory pressure. The flag is suitable when failure can easily be | |
178 | * handled at small cost, such as reduced throughput | |
179 | * | |
180 | * %__GFP_RETRY_MAYFAIL: The VM implementation will retry memory reclaim | |
181 | * procedures that have previously failed if there is some indication | |
182 | * that progress has been made else where. It can wait for other | |
183 | * tasks to attempt high level approaches to freeing memory such as | |
184 | * compaction (which removes fragmentation) and page-out. | |
185 | * There is still a definite limit to the number of retries, but it is | |
186 | * a larger limit than with %__GFP_NORETRY. | |
187 | * Allocations with this flag may fail, but only when there is | |
188 | * genuinely little unused memory. While these allocations do not | |
189 | * directly trigger the OOM killer, their failure indicates that | |
190 | * the system is likely to need to use the OOM killer soon. The | |
191 | * caller must handle failure, but can reasonably do so by failing | |
192 | * a higher-level request, or completing it only in a much less | |
193 | * efficient manner. | |
194 | * If the allocation does fail, and the caller is in a position to | |
195 | * free some non-essential memory, doing so could benefit the system | |
196 | * as a whole. | |
197 | * | |
198 | * %__GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller | |
199 | * cannot handle allocation failures. The allocation could block | |
200 | * indefinitely but will never return with failure. Testing for | |
201 | * failure is pointless. | |
202 | * New users should be evaluated carefully (and the flag should be | |
203 | * used only when there is no reasonable failure policy) but it is | |
204 | * definitely preferable to use the flag rather than opencode endless | |
205 | * loop around allocator. | |
206 | * Using this flag for costly allocations is _highly_ discouraged. | |
207 | */ | |
208 | #define __GFP_IO ((__force gfp_t)___GFP_IO) | |
209 | #define __GFP_FS ((__force gfp_t)___GFP_FS) | |
210 | #define __GFP_DIRECT_RECLAIM ((__force gfp_t)___GFP_DIRECT_RECLAIM) /* Caller can reclaim */ | |
211 | #define __GFP_KSWAPD_RECLAIM ((__force gfp_t)___GFP_KSWAPD_RECLAIM) /* kswapd can wake */ | |
212 | #define __GFP_RECLAIM ((__force gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM)) | |
213 | #define __GFP_RETRY_MAYFAIL ((__force gfp_t)___GFP_RETRY_MAYFAIL) | |
214 | #define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) | |
215 | #define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) | |
216 | ||
217 | /** | |
218 | * DOC: Action modifiers | |
219 | * | |
220 | * Action modifiers | |
221 | * ---------------- | |
222 | * | |
223 | * %__GFP_NOWARN suppresses allocation failure reports. | |
224 | * | |
225 | * %__GFP_COMP address compound page metadata. | |
226 | * | |
227 | * %__GFP_ZERO returns a zeroed page on success. | |
228 | * | |
229 | * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself | |
230 | * is being zeroed (either via __GFP_ZERO or via init_on_alloc, provided that | |
231 | * __GFP_SKIP_ZERO is not set). This flag is intended for optimization: setting | |
232 | * memory tags at the same time as zeroing memory has minimal additional | |
233 | * performace impact. | |
234 | * | |
0a54864f PC |
235 | * %__GFP_SKIP_KASAN makes KASAN skip unpoisoning on page allocation. |
236 | * Used for userspace and vmalloc pages; the latter are unpoisoned by | |
237 | * kasan_unpoison_vmalloc instead. For userspace pages, results in | |
238 | * poisoning being skipped as well, see should_skip_kasan_poison for | |
239 | * details. Only effective in HW_TAGS mode. | |
cb5a065b IM |
240 | */ |
241 | #define __GFP_NOWARN ((__force gfp_t)___GFP_NOWARN) | |
242 | #define __GFP_COMP ((__force gfp_t)___GFP_COMP) | |
243 | #define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) | |
244 | #define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS) | |
245 | #define __GFP_SKIP_ZERO ((__force gfp_t)___GFP_SKIP_ZERO) | |
0a54864f | 246 | #define __GFP_SKIP_KASAN ((__force gfp_t)___GFP_SKIP_KASAN) |
cb5a065b IM |
247 | |
248 | /* Disable lockdep for GFP context tracking */ | |
249 | #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) | |
250 | ||
251 | /* Room for N __GFP_FOO bits */ | |
0a54864f | 252 | #define __GFP_BITS_SHIFT (26 + IS_ENABLED(CONFIG_LOCKDEP)) |
cb5a065b IM |
253 | #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) |
254 | ||
255 | /** | |
256 | * DOC: Useful GFP flag combinations | |
257 | * | |
258 | * Useful GFP flag combinations | |
259 | * ---------------------------- | |
260 | * | |
261 | * Useful GFP flag combinations that are commonly used. It is recommended | |
262 | * that subsystems start with one of these combinations and then set/clear | |
263 | * %__GFP_FOO flags as necessary. | |
264 | * | |
265 | * %GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower | |
266 | * watermark is applied to allow access to "atomic reserves". | |
267 | * The current implementation doesn't support NMI and few other strict | |
268 | * non-preemptive contexts (e.g. raw_spin_lock). The same applies to %GFP_NOWAIT. | |
269 | * | |
270 | * %GFP_KERNEL is typical for kernel-internal allocations. The caller requires | |
271 | * %ZONE_NORMAL or a lower zone for direct access but can direct reclaim. | |
272 | * | |
273 | * %GFP_KERNEL_ACCOUNT is the same as GFP_KERNEL, except the allocation is | |
274 | * accounted to kmemcg. | |
275 | * | |
276 | * %GFP_NOWAIT is for kernel allocations that should not stall for direct | |
277 | * reclaim, start physical IO or use any filesystem callback. | |
278 | * | |
279 | * %GFP_NOIO will use direct reclaim to discard clean pages or slab pages | |
280 | * that do not require the starting of any physical IO. | |
281 | * Please try to avoid using this flag directly and instead use | |
282 | * memalloc_noio_{save,restore} to mark the whole scope which cannot | |
283 | * perform any IO with a short explanation why. All allocation requests | |
284 | * will inherit GFP_NOIO implicitly. | |
285 | * | |
286 | * %GFP_NOFS will use direct reclaim but will not use any filesystem interfaces. | |
287 | * Please try to avoid using this flag directly and instead use | |
288 | * memalloc_nofs_{save,restore} to mark the whole scope which cannot/shouldn't | |
289 | * recurse into the FS layer with a short explanation why. All allocation | |
290 | * requests will inherit GFP_NOFS implicitly. | |
291 | * | |
292 | * %GFP_USER is for userspace allocations that also need to be directly | |
293 | * accessibly by the kernel or hardware. It is typically used by hardware | |
294 | * for buffers that are mapped to userspace (e.g. graphics) that hardware | |
295 | * still must DMA to. cpuset limits are enforced for these allocations. | |
296 | * | |
297 | * %GFP_DMA exists for historical reasons and should be avoided where possible. | |
298 | * The flags indicates that the caller requires that the lowest zone be | |
299 | * used (%ZONE_DMA or 16M on x86-64). Ideally, this would be removed but | |
300 | * it would require careful auditing as some users really require it and | |
301 | * others use the flag to avoid lowmem reserves in %ZONE_DMA and treat the | |
302 | * lowest zone as a type of emergency reserve. | |
303 | * | |
304 | * %GFP_DMA32 is similar to %GFP_DMA except that the caller requires a 32-bit | |
305 | * address. Note that kmalloc(..., GFP_DMA32) does not return DMA32 memory | |
306 | * because the DMA32 kmalloc cache array is not implemented. | |
307 | * (Reason: there is no such user in kernel). | |
308 | * | |
309 | * %GFP_HIGHUSER is for userspace allocations that may be mapped to userspace, | |
310 | * do not need to be directly accessible by the kernel but that cannot | |
311 | * move once in use. An example may be a hardware allocation that maps | |
312 | * data directly into userspace but has no addressing limitations. | |
313 | * | |
314 | * %GFP_HIGHUSER_MOVABLE is for userspace allocations that the kernel does not | |
315 | * need direct access to but can use kmap() when access is required. They | |
316 | * are expected to be movable via page reclaim or page migration. Typically, | |
317 | * pages on the LRU would also be allocated with %GFP_HIGHUSER_MOVABLE. | |
318 | * | |
319 | * %GFP_TRANSHUGE and %GFP_TRANSHUGE_LIGHT are used for THP allocations. They | |
320 | * are compound allocations that will generally fail quickly if memory is not | |
321 | * available and will not wake kswapd/kcompactd on failure. The _LIGHT | |
322 | * version does not attempt reclaim/compaction at all and is by default used | |
323 | * in page fault path, while the non-light is used by khugepaged. | |
324 | */ | |
2973d822 | 325 | #define GFP_ATOMIC (__GFP_HIGH|__GFP_KSWAPD_RECLAIM) |
cb5a065b IM |
326 | #define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS) |
327 | #define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT) | |
328 | #define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM) | |
329 | #define GFP_NOIO (__GFP_RECLAIM) | |
330 | #define GFP_NOFS (__GFP_RECLAIM | __GFP_IO) | |
331 | #define GFP_USER (__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL) | |
332 | #define GFP_DMA __GFP_DMA | |
333 | #define GFP_DMA32 __GFP_DMA32 | |
334 | #define GFP_HIGHUSER (GFP_USER | __GFP_HIGHMEM) | |
0a54864f | 335 | #define GFP_HIGHUSER_MOVABLE (GFP_HIGHUSER | __GFP_MOVABLE | __GFP_SKIP_KASAN) |
cb5a065b IM |
336 | #define GFP_TRANSHUGE_LIGHT ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ |
337 | __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM) | |
338 | #define GFP_TRANSHUGE (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM) | |
339 | ||
340 | #endif /* __LINUX_GFP_TYPES_H */ |