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 |
34 | #define ___GFP_ATOMIC 0x200u |
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 |
50 | #define ___GFP_SKIP_ZERO 0x1000000u |
51 | #define ___GFP_SKIP_KASAN_UNPOISON 0x2000000u |
52 | #define ___GFP_SKIP_KASAN_POISON 0x4000000u |
53 | #else |
54 | #define ___GFP_SKIP_ZERO 0 |
55 | #define ___GFP_SKIP_KASAN_UNPOISON 0 |
56 | #define ___GFP_SKIP_KASAN_POISON 0 |
57 | #endif |
58 | #ifdef CONFIG_LOCKDEP |
59 | #define ___GFP_NOLOCKDEP 0x8000000u |
60 | #else |
61 | #define ___GFP_NOLOCKDEP 0 |
62 | #endif |
63 | /* If the above are modified, __GFP_BITS_SHIFT may need updating */ |
64 | |
65 | /* |
66 | * Physical address zone modifiers (see linux/mmzone.h - low four bits) |
67 | * |
68 | * Do not put any conditional on these. If necessary modify the definitions |
69 | * without the underscores and use them consistently. The definitions here may |
70 | * be used in bit comparisons. |
71 | */ |
72 | #define __GFP_DMA ((__force gfp_t)___GFP_DMA) |
73 | #define __GFP_HIGHMEM ((__force gfp_t)___GFP_HIGHMEM) |
74 | #define __GFP_DMA32 ((__force gfp_t)___GFP_DMA32) |
75 | #define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* ZONE_MOVABLE allowed */ |
76 | #define GFP_ZONEMASK (__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE) |
77 | |
78 | /** |
79 | * DOC: Page mobility and placement hints |
80 | * |
81 | * Page mobility and placement hints |
82 | * --------------------------------- |
83 | * |
84 | * These flags provide hints about how mobile the page is. Pages with similar |
85 | * mobility are placed within the same pageblocks to minimise problems due |
86 | * to external fragmentation. |
87 | * |
88 | * %__GFP_MOVABLE (also a zone modifier) indicates that the page can be |
89 | * moved by page migration during memory compaction or can be reclaimed. |
90 | * |
91 | * %__GFP_RECLAIMABLE is used for slab allocations that specify |
92 | * SLAB_RECLAIM_ACCOUNT and whose pages can be freed via shrinkers. |
93 | * |
94 | * %__GFP_WRITE indicates the caller intends to dirty the page. Where possible, |
95 | * these pages will be spread between local zones to avoid all the dirty |
96 | * pages being in one zone (fair zone allocation policy). |
97 | * |
98 | * %__GFP_HARDWALL enforces the cpuset memory allocation policy. |
99 | * |
100 | * %__GFP_THISNODE forces the allocation to be satisfied from the requested |
101 | * node with no fallbacks or placement policy enforcements. |
102 | * |
103 | * %__GFP_ACCOUNT causes the allocation to be accounted to kmemcg. |
104 | */ |
105 | #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE) |
106 | #define __GFP_WRITE ((__force gfp_t)___GFP_WRITE) |
107 | #define __GFP_HARDWALL ((__force gfp_t)___GFP_HARDWALL) |
108 | #define __GFP_THISNODE ((__force gfp_t)___GFP_THISNODE) |
109 | #define __GFP_ACCOUNT ((__force gfp_t)___GFP_ACCOUNT) |
110 | |
111 | /** |
112 | * DOC: Watermark modifiers |
113 | * |
114 | * Watermark modifiers -- controls access to emergency reserves |
115 | * ------------------------------------------------------------ |
116 | * |
117 | * %__GFP_HIGH indicates that the caller is high-priority and that granting |
118 | * the request is necessary before the system can make forward progress. |
119 | * For example, creating an IO context to clean pages. |
120 | * |
121 | * %__GFP_ATOMIC indicates that the caller cannot reclaim or sleep and is |
122 | * high priority. Users are typically interrupt handlers. This may be |
123 | * used in conjunction with %__GFP_HIGH |
124 | * |
125 | * %__GFP_MEMALLOC allows access to all memory. This should only be used when |
126 | * the caller guarantees the allocation will allow more memory to be freed |
127 | * very shortly e.g. process exiting or swapping. Users either should |
128 | * be the MM or co-ordinating closely with the VM (e.g. swap over NFS). |
129 | * Users of this flag have to be extremely careful to not deplete the reserve |
130 | * completely and implement a throttling mechanism which controls the |
131 | * consumption of the reserve based on the amount of freed memory. |
132 | * Usage of a pre-allocated pool (e.g. mempool) should be always considered |
133 | * before using this flag. |
134 | * |
135 | * %__GFP_NOMEMALLOC is used to explicitly forbid access to emergency reserves. |
136 | * This takes precedence over the %__GFP_MEMALLOC flag if both are set. |
137 | */ |
138 | #define __GFP_ATOMIC ((__force gfp_t)___GFP_ATOMIC) |
139 | #define __GFP_HIGH ((__force gfp_t)___GFP_HIGH) |
140 | #define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC) |
141 | #define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) |
142 | |
143 | /** |
144 | * DOC: Reclaim modifiers |
145 | * |
146 | * Reclaim modifiers |
147 | * ----------------- |
148 | * Please note that all the following flags are only applicable to sleepable |
149 | * allocations (e.g. %GFP_NOWAIT and %GFP_ATOMIC will ignore them). |
150 | * |
151 | * %__GFP_IO can start physical IO. |
152 | * |
153 | * %__GFP_FS can call down to the low-level FS. Clearing the flag avoids the |
154 | * allocator recursing into the filesystem which might already be holding |
155 | * locks. |
156 | * |
157 | * %__GFP_DIRECT_RECLAIM indicates that the caller may enter direct reclaim. |
158 | * This flag can be cleared to avoid unnecessary delays when a fallback |
159 | * option is available. |
160 | * |
161 | * %__GFP_KSWAPD_RECLAIM indicates that the caller wants to wake kswapd when |
162 | * the low watermark is reached and have it reclaim pages until the high |
163 | * watermark is reached. A caller may wish to clear this flag when fallback |
164 | * options are available and the reclaim is likely to disrupt the system. The |
165 | * canonical example is THP allocation where a fallback is cheap but |
166 | * reclaim/compaction may cause indirect stalls. |
167 | * |
168 | * %__GFP_RECLAIM is shorthand to allow/forbid both direct and kswapd reclaim. |
169 | * |
170 | * The default allocator behavior depends on the request size. We have a concept |
171 | * of so called costly allocations (with order > %PAGE_ALLOC_COSTLY_ORDER). |
172 | * !costly allocations are too essential to fail so they are implicitly |
173 | * non-failing by default (with some exceptions like OOM victims might fail so |
174 | * the caller still has to check for failures) while costly requests try to be |
175 | * not disruptive and back off even without invoking the OOM killer. |
176 | * The following three modifiers might be used to override some of these |
177 | * implicit rules |
178 | * |
179 | * %__GFP_NORETRY: The VM implementation will try only very lightweight |
180 | * memory direct reclaim to get some memory under memory pressure (thus |
181 | * it can sleep). It will avoid disruptive actions like OOM killer. The |
182 | * caller must handle the failure which is quite likely to happen under |
183 | * heavy memory pressure. The flag is suitable when failure can easily be |
184 | * handled at small cost, such as reduced throughput |
185 | * |
186 | * %__GFP_RETRY_MAYFAIL: The VM implementation will retry memory reclaim |
187 | * procedures that have previously failed if there is some indication |
188 | * that progress has been made else where. It can wait for other |
189 | * tasks to attempt high level approaches to freeing memory such as |
190 | * compaction (which removes fragmentation) and page-out. |
191 | * There is still a definite limit to the number of retries, but it is |
192 | * a larger limit than with %__GFP_NORETRY. |
193 | * Allocations with this flag may fail, but only when there is |
194 | * genuinely little unused memory. While these allocations do not |
195 | * directly trigger the OOM killer, their failure indicates that |
196 | * the system is likely to need to use the OOM killer soon. The |
197 | * caller must handle failure, but can reasonably do so by failing |
198 | * a higher-level request, or completing it only in a much less |
199 | * efficient manner. |
200 | * If the allocation does fail, and the caller is in a position to |
201 | * free some non-essential memory, doing so could benefit the system |
202 | * as a whole. |
203 | * |
204 | * %__GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller |
205 | * cannot handle allocation failures. The allocation could block |
206 | * indefinitely but will never return with failure. Testing for |
207 | * failure is pointless. |
208 | * New users should be evaluated carefully (and the flag should be |
209 | * used only when there is no reasonable failure policy) but it is |
210 | * definitely preferable to use the flag rather than opencode endless |
211 | * loop around allocator. |
212 | * Using this flag for costly allocations is _highly_ discouraged. |
213 | */ |
214 | #define __GFP_IO ((__force gfp_t)___GFP_IO) |
215 | #define __GFP_FS ((__force gfp_t)___GFP_FS) |
216 | #define __GFP_DIRECT_RECLAIM ((__force gfp_t)___GFP_DIRECT_RECLAIM) /* Caller can reclaim */ |
217 | #define __GFP_KSWAPD_RECLAIM ((__force gfp_t)___GFP_KSWAPD_RECLAIM) /* kswapd can wake */ |
218 | #define __GFP_RECLAIM ((__force gfp_t)(___GFP_DIRECT_RECLAIM|___GFP_KSWAPD_RECLAIM)) |
219 | #define __GFP_RETRY_MAYFAIL ((__force gfp_t)___GFP_RETRY_MAYFAIL) |
220 | #define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) |
221 | #define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) |
222 | |
223 | /** |
224 | * DOC: Action modifiers |
225 | * |
226 | * Action modifiers |
227 | * ---------------- |
228 | * |
229 | * %__GFP_NOWARN suppresses allocation failure reports. |
230 | * |
231 | * %__GFP_COMP address compound page metadata. |
232 | * |
233 | * %__GFP_ZERO returns a zeroed page on success. |
234 | * |
235 | * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself |
236 | * is being zeroed (either via __GFP_ZERO or via init_on_alloc, provided that |
237 | * __GFP_SKIP_ZERO is not set). This flag is intended for optimization: setting |
238 | * memory tags at the same time as zeroing memory has minimal additional |
239 | * performace impact. |
240 | * |
241 | * %__GFP_SKIP_KASAN_UNPOISON makes KASAN skip unpoisoning on page allocation. |
242 | * Only effective in HW_TAGS mode. |
243 | * |
244 | * %__GFP_SKIP_KASAN_POISON makes KASAN skip poisoning on page deallocation. |
245 | * Typically, used for userspace pages. Only effective in HW_TAGS mode. |
246 | */ |
247 | #define __GFP_NOWARN ((__force gfp_t)___GFP_NOWARN) |
248 | #define __GFP_COMP ((__force gfp_t)___GFP_COMP) |
249 | #define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) |
250 | #define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS) |
251 | #define __GFP_SKIP_ZERO ((__force gfp_t)___GFP_SKIP_ZERO) |
252 | #define __GFP_SKIP_KASAN_UNPOISON ((__force gfp_t)___GFP_SKIP_KASAN_UNPOISON) |
253 | #define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON) |
254 | |
255 | /* Disable lockdep for GFP context tracking */ |
256 | #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) |
257 | |
258 | /* Room for N __GFP_FOO bits */ |
259 | #define __GFP_BITS_SHIFT (27 + IS_ENABLED(CONFIG_LOCKDEP)) |
260 | #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) |
261 | |
262 | /** |
263 | * DOC: Useful GFP flag combinations |
264 | * |
265 | * Useful GFP flag combinations |
266 | * ---------------------------- |
267 | * |
268 | * Useful GFP flag combinations that are commonly used. It is recommended |
269 | * that subsystems start with one of these combinations and then set/clear |
270 | * %__GFP_FOO flags as necessary. |
271 | * |
272 | * %GFP_ATOMIC users can not sleep and need the allocation to succeed. A lower |
273 | * watermark is applied to allow access to "atomic reserves". |
274 | * The current implementation doesn't support NMI and few other strict |
275 | * non-preemptive contexts (e.g. raw_spin_lock). The same applies to %GFP_NOWAIT. |
276 | * |
277 | * %GFP_KERNEL is typical for kernel-internal allocations. The caller requires |
278 | * %ZONE_NORMAL or a lower zone for direct access but can direct reclaim. |
279 | * |
280 | * %GFP_KERNEL_ACCOUNT is the same as GFP_KERNEL, except the allocation is |
281 | * accounted to kmemcg. |
282 | * |
283 | * %GFP_NOWAIT is for kernel allocations that should not stall for direct |
284 | * reclaim, start physical IO or use any filesystem callback. |
285 | * |
286 | * %GFP_NOIO will use direct reclaim to discard clean pages or slab pages |
287 | * that do not require the starting of any physical IO. |
288 | * Please try to avoid using this flag directly and instead use |
289 | * memalloc_noio_{save,restore} to mark the whole scope which cannot |
290 | * perform any IO with a short explanation why. All allocation requests |
291 | * will inherit GFP_NOIO implicitly. |
292 | * |
293 | * %GFP_NOFS will use direct reclaim but will not use any filesystem interfaces. |
294 | * Please try to avoid using this flag directly and instead use |
295 | * memalloc_nofs_{save,restore} to mark the whole scope which cannot/shouldn't |
296 | * recurse into the FS layer with a short explanation why. All allocation |
297 | * requests will inherit GFP_NOFS implicitly. |
298 | * |
299 | * %GFP_USER is for userspace allocations that also need to be directly |
300 | * accessibly by the kernel or hardware. It is typically used by hardware |
301 | * for buffers that are mapped to userspace (e.g. graphics) that hardware |
302 | * still must DMA to. cpuset limits are enforced for these allocations. |
303 | * |
304 | * %GFP_DMA exists for historical reasons and should be avoided where possible. |
305 | * The flags indicates that the caller requires that the lowest zone be |
306 | * used (%ZONE_DMA or 16M on x86-64). Ideally, this would be removed but |
307 | * it would require careful auditing as some users really require it and |
308 | * others use the flag to avoid lowmem reserves in %ZONE_DMA and treat the |
309 | * lowest zone as a type of emergency reserve. |
310 | * |
311 | * %GFP_DMA32 is similar to %GFP_DMA except that the caller requires a 32-bit |
312 | * address. Note that kmalloc(..., GFP_DMA32) does not return DMA32 memory |
313 | * because the DMA32 kmalloc cache array is not implemented. |
314 | * (Reason: there is no such user in kernel). |
315 | * |
316 | * %GFP_HIGHUSER is for userspace allocations that may be mapped to userspace, |
317 | * do not need to be directly accessible by the kernel but that cannot |
318 | * move once in use. An example may be a hardware allocation that maps |
319 | * data directly into userspace but has no addressing limitations. |
320 | * |
321 | * %GFP_HIGHUSER_MOVABLE is for userspace allocations that the kernel does not |
322 | * need direct access to but can use kmap() when access is required. They |
323 | * are expected to be movable via page reclaim or page migration. Typically, |
324 | * pages on the LRU would also be allocated with %GFP_HIGHUSER_MOVABLE. |
325 | * |
326 | * %GFP_TRANSHUGE and %GFP_TRANSHUGE_LIGHT are used for THP allocations. They |
327 | * are compound allocations that will generally fail quickly if memory is not |
328 | * available and will not wake kswapd/kcompactd on failure. The _LIGHT |
329 | * version does not attempt reclaim/compaction at all and is by default used |
330 | * in page fault path, while the non-light is used by khugepaged. |
331 | */ |
332 | #define GFP_ATOMIC (__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM) |
333 | #define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS) |
334 | #define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT) |
335 | #define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM) |
336 | #define GFP_NOIO (__GFP_RECLAIM) |
337 | #define GFP_NOFS (__GFP_RECLAIM | __GFP_IO) |
338 | #define GFP_USER (__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL) |
339 | #define GFP_DMA __GFP_DMA |
340 | #define GFP_DMA32 __GFP_DMA32 |
341 | #define GFP_HIGHUSER (GFP_USER | __GFP_HIGHMEM) |
342 | #define GFP_HIGHUSER_MOVABLE (GFP_HIGHUSER | __GFP_MOVABLE | \ |
343 | __GFP_SKIP_KASAN_POISON | __GFP_SKIP_KASAN_UNPOISON) |
344 | #define GFP_TRANSHUGE_LIGHT ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ |
345 | __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM) |
346 | #define GFP_TRANSHUGE (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM) |
347 | |
348 | #endif /* __LINUX_GFP_TYPES_H */ |
349 | |