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5981690d DW |
1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | /* Copyright(c) 2015 Intel Corporation. All rights reserved. */ | |
7d3dcf26 | 3 | #include <linux/device.h> |
92281dee | 4 | #include <linux/io.h> |
0207df4f | 5 | #include <linux/kasan.h> |
41e94a85 | 6 | #include <linux/memory_hotplug.h> |
bcfa4b72 MW |
7 | #include <linux/mm.h> |
8 | #include <linux/pfn_t.h> | |
5042db43 | 9 | #include <linux/swap.h> |
9ffc1d19 | 10 | #include <linux/mmzone.h> |
5042db43 | 11 | #include <linux/swapops.h> |
bcfa4b72 | 12 | #include <linux/types.h> |
e7638488 | 13 | #include <linux/wait_bit.h> |
bcfa4b72 | 14 | #include <linux/xarray.h> |
92281dee | 15 | |
bcfa4b72 | 16 | static DEFINE_XARRAY(pgmap_array); |
9476df7d | 17 | |
9ffc1d19 DW |
18 | /* |
19 | * The memremap() and memremap_pages() interfaces are alternately used | |
20 | * to map persistent memory namespaces. These interfaces place different | |
21 | * constraints on the alignment and size of the mapping (namespace). | |
22 | * memremap() can map individual PAGE_SIZE pages. memremap_pages() can | |
23 | * only map subsections (2MB), and at least one architecture (PowerPC) | |
24 | * the minimum mapping granularity of memremap_pages() is 16MB. | |
25 | * | |
26 | * The role of memremap_compat_align() is to communicate the minimum | |
27 | * arch supported alignment of a namespace such that it can freely | |
28 | * switch modes without violating the arch constraint. Namely, do not | |
29 | * allow a namespace to be PAGE_SIZE aligned since that namespace may be | |
30 | * reconfigured into a mode that requires SUBSECTION_SIZE alignment. | |
31 | */ | |
32 | #ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN | |
33 | unsigned long memremap_compat_align(void) | |
34 | { | |
35 | return SUBSECTION_SIZE; | |
36 | } | |
37 | EXPORT_SYMBOL_GPL(memremap_compat_align); | |
38 | #endif | |
39 | ||
f6a55e1a CH |
40 | #ifdef CONFIG_DEV_PAGEMAP_OPS |
41 | DEFINE_STATIC_KEY_FALSE(devmap_managed_key); | |
42 | EXPORT_SYMBOL(devmap_managed_key); | |
f6a55e1a | 43 | |
46b1ee38 | 44 | static void devmap_managed_enable_put(struct dev_pagemap *pgmap) |
f6a55e1a | 45 | { |
46b1ee38 RC |
46 | if (pgmap->type == MEMORY_DEVICE_PRIVATE || |
47 | pgmap->type == MEMORY_DEVICE_FS_DAX) | |
48 | static_branch_dec(&devmap_managed_key); | |
f6a55e1a CH |
49 | } |
50 | ||
46b1ee38 | 51 | static void devmap_managed_enable_get(struct dev_pagemap *pgmap) |
f6a55e1a | 52 | { |
46b1ee38 RC |
53 | if (pgmap->type == MEMORY_DEVICE_PRIVATE || |
54 | pgmap->type == MEMORY_DEVICE_FS_DAX) | |
55 | static_branch_inc(&devmap_managed_key); | |
f6a55e1a CH |
56 | } |
57 | #else | |
46b1ee38 | 58 | static void devmap_managed_enable_get(struct dev_pagemap *pgmap) |
f6a55e1a | 59 | { |
f6a55e1a | 60 | } |
46b1ee38 | 61 | static void devmap_managed_enable_put(struct dev_pagemap *pgmap) |
6f42193f CH |
62 | { |
63 | } | |
f6a55e1a CH |
64 | #endif /* CONFIG_DEV_PAGEMAP_OPS */ |
65 | ||
a4574f63 | 66 | static void pgmap_array_delete(struct range *range) |
ab1b597e | 67 | { |
a4574f63 | 68 | xa_store_range(&pgmap_array, PHYS_PFN(range->start), PHYS_PFN(range->end), |
bcfa4b72 | 69 | NULL, GFP_KERNEL); |
ab1b597e | 70 | synchronize_rcu(); |
9476df7d DW |
71 | } |
72 | ||
b7b3c01b | 73 | static unsigned long pfn_first(struct dev_pagemap *pgmap, int range_id) |
5c2c2587 | 74 | { |
b7b3c01b DW |
75 | struct range *range = &pgmap->ranges[range_id]; |
76 | unsigned long pfn = PHYS_PFN(range->start); | |
77 | ||
78 | if (range_id) | |
79 | return pfn; | |
80 | return pfn + vmem_altmap_offset(pgmap_altmap(pgmap)); | |
5c2c2587 DW |
81 | } |
82 | ||
b7b3c01b | 83 | static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id) |
5c2c2587 | 84 | { |
b7b3c01b | 85 | const struct range *range = &pgmap->ranges[range_id]; |
5c2c2587 | 86 | |
a4574f63 | 87 | return (range->start + range_len(range)) >> PAGE_SHIFT; |
5c2c2587 DW |
88 | } |
89 | ||
949b9325 DW |
90 | static unsigned long pfn_next(unsigned long pfn) |
91 | { | |
92 | if (pfn % 1024 == 0) | |
93 | cond_resched(); | |
94 | return pfn + 1; | |
95 | } | |
96 | ||
b7b3c01b DW |
97 | #define for_each_device_pfn(pfn, map, i) \ |
98 | for (pfn = pfn_first(map, i); pfn < pfn_end(map, i); pfn = pfn_next(pfn)) | |
5c2c2587 | 99 | |
24917f6b CH |
100 | static void dev_pagemap_kill(struct dev_pagemap *pgmap) |
101 | { | |
102 | if (pgmap->ops && pgmap->ops->kill) | |
103 | pgmap->ops->kill(pgmap); | |
104 | else | |
105 | percpu_ref_kill(pgmap->ref); | |
106 | } | |
107 | ||
108 | static void dev_pagemap_cleanup(struct dev_pagemap *pgmap) | |
109 | { | |
110 | if (pgmap->ops && pgmap->ops->cleanup) { | |
111 | pgmap->ops->cleanup(pgmap); | |
112 | } else { | |
113 | wait_for_completion(&pgmap->done); | |
114 | percpu_ref_exit(pgmap->ref); | |
115 | } | |
06282373 DW |
116 | /* |
117 | * Undo the pgmap ref assignment for the internal case as the | |
118 | * caller may re-enable the same pgmap. | |
119 | */ | |
120 | if (pgmap->ref == &pgmap->internal_ref) | |
121 | pgmap->ref = NULL; | |
24917f6b CH |
122 | } |
123 | ||
b7b3c01b | 124 | static void pageunmap_range(struct dev_pagemap *pgmap, int range_id) |
41e94a85 | 125 | { |
b7b3c01b | 126 | struct range *range = &pgmap->ranges[range_id]; |
77e080e7 | 127 | struct page *first_page; |
2c2a5af6 | 128 | int nid; |
71389703 | 129 | |
77e080e7 | 130 | /* make sure to access a memmap that was actually initialized */ |
b7b3c01b | 131 | first_page = pfn_to_page(pfn_first(pgmap, range_id)); |
77e080e7 | 132 | |
41e94a85 | 133 | /* pages are dead and unused, undo the arch mapping */ |
77e080e7 | 134 | nid = page_to_nid(first_page); |
2c2a5af6 | 135 | |
f931ab47 | 136 | mem_hotplug_begin(); |
a4574f63 DW |
137 | remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start), |
138 | PHYS_PFN(range_len(range))); | |
69324b8f | 139 | if (pgmap->type == MEMORY_DEVICE_PRIVATE) { |
a4574f63 DW |
140 | __remove_pages(PHYS_PFN(range->start), |
141 | PHYS_PFN(range_len(range)), NULL); | |
69324b8f | 142 | } else { |
a4574f63 | 143 | arch_remove_memory(nid, range->start, range_len(range), |
514caf23 | 144 | pgmap_altmap(pgmap)); |
a4574f63 | 145 | kasan_remove_zero_shadow(__va(range->start), range_len(range)); |
69324b8f | 146 | } |
f931ab47 | 147 | mem_hotplug_done(); |
b5d24fda | 148 | |
a4574f63 DW |
149 | untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range)); |
150 | pgmap_array_delete(range); | |
b7b3c01b DW |
151 | } |
152 | ||
153 | void memunmap_pages(struct dev_pagemap *pgmap) | |
154 | { | |
155 | unsigned long pfn; | |
156 | int i; | |
157 | ||
158 | dev_pagemap_kill(pgmap); | |
159 | for (i = 0; i < pgmap->nr_range; i++) | |
160 | for_each_device_pfn(pfn, pgmap, i) | |
161 | put_page(pfn_to_page(pfn)); | |
162 | dev_pagemap_cleanup(pgmap); | |
163 | ||
164 | for (i = 0; i < pgmap->nr_range; i++) | |
165 | pageunmap_range(pgmap, i); | |
166 | ||
fdc029b1 | 167 | WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n"); |
46b1ee38 | 168 | devmap_managed_enable_put(pgmap); |
9476df7d | 169 | } |
6869b7b2 CH |
170 | EXPORT_SYMBOL_GPL(memunmap_pages); |
171 | ||
172 | static void devm_memremap_pages_release(void *data) | |
173 | { | |
174 | memunmap_pages(data); | |
175 | } | |
9476df7d | 176 | |
24917f6b CH |
177 | static void dev_pagemap_percpu_release(struct percpu_ref *ref) |
178 | { | |
179 | struct dev_pagemap *pgmap = | |
180 | container_of(ref, struct dev_pagemap, internal_ref); | |
181 | ||
182 | complete(&pgmap->done); | |
183 | } | |
184 | ||
b7b3c01b DW |
185 | static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, |
186 | int range_id, int nid) | |
41e94a85 | 187 | { |
b7b3c01b | 188 | struct range *range = &pgmap->ranges[range_id]; |
966cf44f | 189 | struct dev_pagemap *conflict_pgmap; |
6869b7b2 | 190 | int error, is_ram; |
5f29a77c | 191 | |
b7b3c01b DW |
192 | if (WARN_ONCE(pgmap_altmap(pgmap) && range_id > 0, |
193 | "altmap not supported for multiple ranges\n")) | |
194 | return -EINVAL; | |
f6a55e1a | 195 | |
a4574f63 | 196 | conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL); |
15d36fec | 197 | if (conflict_pgmap) { |
6869b7b2 | 198 | WARN(1, "Conflicting mapping in same section\n"); |
15d36fec | 199 | put_dev_pagemap(conflict_pgmap); |
b7b3c01b | 200 | return -ENOMEM; |
15d36fec DJ |
201 | } |
202 | ||
a4574f63 | 203 | conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL); |
15d36fec | 204 | if (conflict_pgmap) { |
6869b7b2 | 205 | WARN(1, "Conflicting mapping in same section\n"); |
15d36fec | 206 | put_dev_pagemap(conflict_pgmap); |
b7b3c01b | 207 | return -ENOMEM; |
15d36fec DJ |
208 | } |
209 | ||
a4574f63 | 210 | is_ram = region_intersects(range->start, range_len(range), |
d37a14bb | 211 | IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); |
41e94a85 | 212 | |
06489cfb | 213 | if (is_ram != REGION_DISJOINT) { |
a4574f63 DW |
214 | WARN_ONCE(1, "attempted on %s region %#llx-%#llx\n", |
215 | is_ram == REGION_MIXED ? "mixed" : "ram", | |
216 | range->start, range->end); | |
b7b3c01b | 217 | return -ENXIO; |
41e94a85 CH |
218 | } |
219 | ||
a4574f63 DW |
220 | error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(range->start), |
221 | PHYS_PFN(range->end), pgmap, GFP_KERNEL)); | |
9476df7d | 222 | if (error) |
b7b3c01b | 223 | return error; |
9476df7d | 224 | |
41e94a85 | 225 | if (nid < 0) |
7eff93b7 | 226 | nid = numa_mem_id(); |
41e94a85 | 227 | |
b7b3c01b | 228 | error = track_pfn_remap(NULL, ¶ms->pgprot, PHYS_PFN(range->start), 0, |
a4574f63 | 229 | range_len(range)); |
9049771f DW |
230 | if (error) |
231 | goto err_pfn_remap; | |
232 | ||
f931ab47 | 233 | mem_hotplug_begin(); |
69324b8f DW |
234 | |
235 | /* | |
236 | * For device private memory we call add_pages() as we only need to | |
237 | * allocate and initialize struct page for the device memory. More- | |
238 | * over the device memory is un-accessible thus we do not want to | |
239 | * create a linear mapping for the memory like arch_add_memory() | |
240 | * would do. | |
241 | * | |
242 | * For all other device memory types, which are accessible by | |
243 | * the CPU, we do want the linear mapping and thus use | |
244 | * arch_add_memory(). | |
245 | */ | |
246 | if (pgmap->type == MEMORY_DEVICE_PRIVATE) { | |
a4574f63 | 247 | error = add_pages(nid, PHYS_PFN(range->start), |
b7b3c01b | 248 | PHYS_PFN(range_len(range)), params); |
69324b8f | 249 | } else { |
a4574f63 | 250 | error = kasan_add_zero_shadow(__va(range->start), range_len(range)); |
69324b8f DW |
251 | if (error) { |
252 | mem_hotplug_done(); | |
253 | goto err_kasan; | |
254 | } | |
255 | ||
a4574f63 | 256 | error = arch_add_memory(nid, range->start, range_len(range), |
b7b3c01b | 257 | params); |
69324b8f DW |
258 | } |
259 | ||
260 | if (!error) { | |
261 | struct zone *zone; | |
262 | ||
263 | zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE]; | |
a4574f63 | 264 | move_pfn_range_to_zone(zone, PHYS_PFN(range->start), |
d882c006 DH |
265 | PHYS_PFN(range_len(range)), params->altmap, |
266 | MIGRATE_MOVABLE); | |
0207df4f AR |
267 | } |
268 | ||
f931ab47 | 269 | mem_hotplug_done(); |
9476df7d DW |
270 | if (error) |
271 | goto err_add_memory; | |
41e94a85 | 272 | |
966cf44f AD |
273 | /* |
274 | * Initialization of the pages has been deferred until now in order | |
275 | * to allow us to do the work while not holding the hotplug lock. | |
276 | */ | |
277 | memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], | |
a4574f63 DW |
278 | PHYS_PFN(range->start), |
279 | PHYS_PFN(range_len(range)), pgmap); | |
b7b3c01b DW |
280 | percpu_ref_get_many(pgmap->ref, pfn_end(pgmap, range_id) |
281 | - pfn_first(pgmap, range_id)); | |
282 | return 0; | |
9476df7d | 283 | |
b7b3c01b | 284 | err_add_memory: |
a4574f63 | 285 | kasan_remove_zero_shadow(__va(range->start), range_len(range)); |
b7b3c01b | 286 | err_kasan: |
a4574f63 | 287 | untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range)); |
b7b3c01b | 288 | err_pfn_remap: |
a4574f63 | 289 | pgmap_array_delete(range); |
b7b3c01b DW |
290 | return error; |
291 | } | |
292 | ||
293 | ||
294 | /* | |
295 | * Not device managed version of dev_memremap_pages, undone by | |
296 | * memunmap_pages(). Please use dev_memremap_pages if you have a struct | |
297 | * device available. | |
298 | */ | |
299 | void *memremap_pages(struct dev_pagemap *pgmap, int nid) | |
300 | { | |
301 | struct mhp_params params = { | |
302 | .altmap = pgmap_altmap(pgmap), | |
303 | .pgprot = PAGE_KERNEL, | |
304 | }; | |
305 | const int nr_range = pgmap->nr_range; | |
b7b3c01b DW |
306 | int error, i; |
307 | ||
308 | if (WARN_ONCE(!nr_range, "nr_range must be specified\n")) | |
309 | return ERR_PTR(-EINVAL); | |
310 | ||
311 | switch (pgmap->type) { | |
312 | case MEMORY_DEVICE_PRIVATE: | |
313 | if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) { | |
314 | WARN(1, "Device private memory not supported\n"); | |
315 | return ERR_PTR(-EINVAL); | |
316 | } | |
317 | if (!pgmap->ops || !pgmap->ops->migrate_to_ram) { | |
318 | WARN(1, "Missing migrate_to_ram method\n"); | |
319 | return ERR_PTR(-EINVAL); | |
320 | } | |
46b1ee38 RC |
321 | if (!pgmap->ops->page_free) { |
322 | WARN(1, "Missing page_free method\n"); | |
323 | return ERR_PTR(-EINVAL); | |
324 | } | |
b7b3c01b DW |
325 | if (!pgmap->owner) { |
326 | WARN(1, "Missing owner\n"); | |
327 | return ERR_PTR(-EINVAL); | |
328 | } | |
329 | break; | |
330 | case MEMORY_DEVICE_FS_DAX: | |
331 | if (!IS_ENABLED(CONFIG_ZONE_DEVICE) || | |
332 | IS_ENABLED(CONFIG_FS_DAX_LIMITED)) { | |
333 | WARN(1, "File system DAX not supported\n"); | |
334 | return ERR_PTR(-EINVAL); | |
335 | } | |
336 | break; | |
337 | case MEMORY_DEVICE_GENERIC: | |
b7b3c01b DW |
338 | break; |
339 | case MEMORY_DEVICE_PCI_P2PDMA: | |
340 | params.pgprot = pgprot_noncached(params.pgprot); | |
b7b3c01b DW |
341 | break; |
342 | default: | |
343 | WARN(1, "Invalid pgmap type %d\n", pgmap->type); | |
344 | break; | |
345 | } | |
346 | ||
347 | if (!pgmap->ref) { | |
348 | if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup)) | |
349 | return ERR_PTR(-EINVAL); | |
350 | ||
351 | init_completion(&pgmap->done); | |
352 | error = percpu_ref_init(&pgmap->internal_ref, | |
353 | dev_pagemap_percpu_release, 0, GFP_KERNEL); | |
354 | if (error) | |
355 | return ERR_PTR(error); | |
356 | pgmap->ref = &pgmap->internal_ref; | |
357 | } else { | |
358 | if (!pgmap->ops || !pgmap->ops->kill || !pgmap->ops->cleanup) { | |
359 | WARN(1, "Missing reference count teardown definition\n"); | |
360 | return ERR_PTR(-EINVAL); | |
361 | } | |
362 | } | |
363 | ||
46b1ee38 | 364 | devmap_managed_enable_get(pgmap); |
b7b3c01b DW |
365 | |
366 | /* | |
367 | * Clear the pgmap nr_range as it will be incremented for each | |
368 | * successfully processed range. This communicates how many | |
369 | * regions to unwind in the abort case. | |
370 | */ | |
371 | pgmap->nr_range = 0; | |
372 | error = 0; | |
373 | for (i = 0; i < nr_range; i++) { | |
374 | error = pagemap_range(pgmap, ¶ms, i, nid); | |
375 | if (error) | |
376 | break; | |
377 | pgmap->nr_range++; | |
378 | } | |
379 | ||
380 | if (i < nr_range) { | |
381 | memunmap_pages(pgmap); | |
382 | pgmap->nr_range = nr_range; | |
383 | return ERR_PTR(error); | |
384 | } | |
385 | ||
386 | return __va(pgmap->ranges[0].start); | |
41e94a85 | 387 | } |
6869b7b2 CH |
388 | EXPORT_SYMBOL_GPL(memremap_pages); |
389 | ||
390 | /** | |
391 | * devm_memremap_pages - remap and provide memmap backing for the given resource | |
392 | * @dev: hosting device for @res | |
393 | * @pgmap: pointer to a struct dev_pagemap | |
394 | * | |
395 | * Notes: | |
396 | * 1/ At a minimum the res and type members of @pgmap must be initialized | |
397 | * by the caller before passing it to this function | |
398 | * | |
399 | * 2/ The altmap field may optionally be initialized, in which case | |
400 | * PGMAP_ALTMAP_VALID must be set in pgmap->flags. | |
401 | * | |
402 | * 3/ The ref field may optionally be provided, in which pgmap->ref must be | |
403 | * 'live' on entry and will be killed and reaped at | |
404 | * devm_memremap_pages_release() time, or if this routine fails. | |
405 | * | |
a4574f63 | 406 | * 4/ range is expected to be a host memory range that could feasibly be |
6869b7b2 CH |
407 | * treated as a "System RAM" range, i.e. not a device mmio range, but |
408 | * this is not enforced. | |
409 | */ | |
410 | void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) | |
411 | { | |
412 | int error; | |
413 | void *ret; | |
414 | ||
415 | ret = memremap_pages(pgmap, dev_to_node(dev)); | |
416 | if (IS_ERR(ret)) | |
417 | return ret; | |
418 | ||
419 | error = devm_add_action_or_reset(dev, devm_memremap_pages_release, | |
420 | pgmap); | |
421 | if (error) | |
422 | return ERR_PTR(error); | |
423 | return ret; | |
424 | } | |
808153e1 | 425 | EXPORT_SYMBOL_GPL(devm_memremap_pages); |
4b94ffdc | 426 | |
2e3f139e DW |
427 | void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap) |
428 | { | |
429 | devm_release_action(dev, devm_memremap_pages_release, pgmap); | |
430 | } | |
431 | EXPORT_SYMBOL_GPL(devm_memunmap_pages); | |
432 | ||
4b94ffdc DW |
433 | unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) |
434 | { | |
435 | /* number of pfns from base where pfn_to_page() is valid */ | |
514caf23 CH |
436 | if (altmap) |
437 | return altmap->reserve + altmap->free; | |
438 | return 0; | |
4b94ffdc DW |
439 | } |
440 | ||
441 | void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns) | |
442 | { | |
443 | altmap->alloc -= nr_pfns; | |
444 | } | |
445 | ||
0822acb8 CH |
446 | /** |
447 | * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn | |
448 | * @pfn: page frame number to lookup page_map | |
449 | * @pgmap: optional known pgmap that already has a reference | |
450 | * | |
832d7aa0 CH |
451 | * If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap |
452 | * is non-NULL but does not cover @pfn the reference to it will be released. | |
0822acb8 CH |
453 | */ |
454 | struct dev_pagemap *get_dev_pagemap(unsigned long pfn, | |
455 | struct dev_pagemap *pgmap) | |
456 | { | |
0822acb8 CH |
457 | resource_size_t phys = PFN_PHYS(pfn); |
458 | ||
459 | /* | |
832d7aa0 | 460 | * In the cached case we're already holding a live reference. |
0822acb8 | 461 | */ |
832d7aa0 | 462 | if (pgmap) { |
a4574f63 | 463 | if (phys >= pgmap->range.start && phys <= pgmap->range.end) |
832d7aa0 CH |
464 | return pgmap; |
465 | put_dev_pagemap(pgmap); | |
0822acb8 CH |
466 | } |
467 | ||
468 | /* fall back to slow path lookup */ | |
469 | rcu_read_lock(); | |
bcfa4b72 | 470 | pgmap = xa_load(&pgmap_array, PHYS_PFN(phys)); |
0822acb8 CH |
471 | if (pgmap && !percpu_ref_tryget_live(pgmap->ref)) |
472 | pgmap = NULL; | |
473 | rcu_read_unlock(); | |
474 | ||
475 | return pgmap; | |
476 | } | |
e7638488 | 477 | EXPORT_SYMBOL_GPL(get_dev_pagemap); |
7b2d55d2 | 478 | |
e7638488 | 479 | #ifdef CONFIG_DEV_PAGEMAP_OPS |
07d80269 | 480 | void free_devmap_managed_page(struct page *page) |
7b2d55d2 | 481 | { |
429589d6 DW |
482 | /* notify page idle for dax */ |
483 | if (!is_device_private_page(page)) { | |
484 | wake_up_var(&page->_refcount); | |
485 | return; | |
486 | } | |
7ab0ad0e | 487 | |
429589d6 DW |
488 | __ClearPageWaiters(page); |
489 | ||
490 | mem_cgroup_uncharge(page); | |
491 | ||
492 | /* | |
493 | * When a device_private page is freed, the page->mapping field | |
494 | * may still contain a (stale) mapping value. For example, the | |
495 | * lower bits of page->mapping may still identify the page as an | |
496 | * anonymous page. Ultimately, this entire field is just stale | |
497 | * and wrong, and it will cause errors if not cleared. One | |
498 | * example is: | |
499 | * | |
500 | * migrate_vma_pages() | |
501 | * migrate_vma_insert_page() | |
502 | * page_add_new_anon_rmap() | |
503 | * __page_set_anon_rmap() | |
504 | * ...checks page->mapping, via PageAnon(page) call, | |
505 | * and incorrectly concludes that the page is an | |
506 | * anonymous page. Therefore, it incorrectly, | |
507 | * silently fails to set up the new anon rmap. | |
508 | * | |
509 | * For other types of ZONE_DEVICE pages, migration is either | |
510 | * handled differently or not done at all, so there is no need | |
511 | * to clear page->mapping. | |
512 | */ | |
513 | page->mapping = NULL; | |
514 | page->pgmap->ops->page_free(page); | |
7b2d55d2 | 515 | } |
e7638488 | 516 | #endif /* CONFIG_DEV_PAGEMAP_OPS */ |