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1 | /* | |
2 | * Generic hugetlb support. | |
3 | * (C) Nadia Yvette Chambers, April 2004 | |
4 | */ | |
5 | #include <linux/list.h> | |
6 | #include <linux/init.h> | |
7 | #include <linux/module.h> | |
8 | #include <linux/mm.h> | |
9 | #include <linux/seq_file.h> | |
10 | #include <linux/sysctl.h> | |
11 | #include <linux/highmem.h> | |
12 | #include <linux/mmu_notifier.h> | |
13 | #include <linux/nodemask.h> | |
14 | #include <linux/pagemap.h> | |
15 | #include <linux/mempolicy.h> | |
16 | #include <linux/compiler.h> | |
17 | #include <linux/cpuset.h> | |
18 | #include <linux/mutex.h> | |
19 | #include <linux/bootmem.h> | |
20 | #include <linux/sysfs.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/rmap.h> | |
23 | #include <linux/swap.h> | |
24 | #include <linux/swapops.h> | |
25 | #include <linux/page-isolation.h> | |
26 | #include <linux/jhash.h> | |
27 | ||
28 | #include <asm/page.h> | |
29 | #include <asm/pgtable.h> | |
30 | #include <asm/tlb.h> | |
31 | ||
32 | #include <linux/io.h> | |
33 | #include <linux/hugetlb.h> | |
34 | #include <linux/hugetlb_cgroup.h> | |
35 | #include <linux/node.h> | |
36 | #include "internal.h" | |
37 | ||
38 | int hugepages_treat_as_movable; | |
39 | ||
40 | int hugetlb_max_hstate __read_mostly; | |
41 | unsigned int default_hstate_idx; | |
42 | struct hstate hstates[HUGE_MAX_HSTATE]; | |
43 | ||
44 | __initdata LIST_HEAD(huge_boot_pages); | |
45 | ||
46 | /* for command line parsing */ | |
47 | static struct hstate * __initdata parsed_hstate; | |
48 | static unsigned long __initdata default_hstate_max_huge_pages; | |
49 | static unsigned long __initdata default_hstate_size; | |
50 | ||
51 | /* | |
52 | * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages, | |
53 | * free_huge_pages, and surplus_huge_pages. | |
54 | */ | |
55 | DEFINE_SPINLOCK(hugetlb_lock); | |
56 | ||
57 | /* | |
58 | * Serializes faults on the same logical page. This is used to | |
59 | * prevent spurious OOMs when the hugepage pool is fully utilized. | |
60 | */ | |
61 | static int num_fault_mutexes; | |
62 | static struct mutex *htlb_fault_mutex_table ____cacheline_aligned_in_smp; | |
63 | ||
64 | /* Forward declaration */ | |
65 | static int hugetlb_acct_memory(struct hstate *h, long delta); | |
66 | ||
67 | static inline void unlock_or_release_subpool(struct hugepage_subpool *spool) | |
68 | { | |
69 | bool free = (spool->count == 0) && (spool->used_hpages == 0); | |
70 | ||
71 | spin_unlock(&spool->lock); | |
72 | ||
73 | /* If no pages are used, and no other handles to the subpool | |
74 | * remain, give up any reservations mased on minimum size and | |
75 | * free the subpool */ | |
76 | if (free) { | |
77 | if (spool->min_hpages != -1) | |
78 | hugetlb_acct_memory(spool->hstate, | |
79 | -spool->min_hpages); | |
80 | kfree(spool); | |
81 | } | |
82 | } | |
83 | ||
84 | struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages, | |
85 | long min_hpages) | |
86 | { | |
87 | struct hugepage_subpool *spool; | |
88 | ||
89 | spool = kzalloc(sizeof(*spool), GFP_KERNEL); | |
90 | if (!spool) | |
91 | return NULL; | |
92 | ||
93 | spin_lock_init(&spool->lock); | |
94 | spool->count = 1; | |
95 | spool->max_hpages = max_hpages; | |
96 | spool->hstate = h; | |
97 | spool->min_hpages = min_hpages; | |
98 | ||
99 | if (min_hpages != -1 && hugetlb_acct_memory(h, min_hpages)) { | |
100 | kfree(spool); | |
101 | return NULL; | |
102 | } | |
103 | spool->rsv_hpages = min_hpages; | |
104 | ||
105 | return spool; | |
106 | } | |
107 | ||
108 | void hugepage_put_subpool(struct hugepage_subpool *spool) | |
109 | { | |
110 | spin_lock(&spool->lock); | |
111 | BUG_ON(!spool->count); | |
112 | spool->count--; | |
113 | unlock_or_release_subpool(spool); | |
114 | } | |
115 | ||
116 | /* | |
117 | * Subpool accounting for allocating and reserving pages. | |
118 | * Return -ENOMEM if there are not enough resources to satisfy the | |
119 | * the request. Otherwise, return the number of pages by which the | |
120 | * global pools must be adjusted (upward). The returned value may | |
121 | * only be different than the passed value (delta) in the case where | |
122 | * a subpool minimum size must be manitained. | |
123 | */ | |
124 | static long hugepage_subpool_get_pages(struct hugepage_subpool *spool, | |
125 | long delta) | |
126 | { | |
127 | long ret = delta; | |
128 | ||
129 | if (!spool) | |
130 | return ret; | |
131 | ||
132 | spin_lock(&spool->lock); | |
133 | ||
134 | if (spool->max_hpages != -1) { /* maximum size accounting */ | |
135 | if ((spool->used_hpages + delta) <= spool->max_hpages) | |
136 | spool->used_hpages += delta; | |
137 | else { | |
138 | ret = -ENOMEM; | |
139 | goto unlock_ret; | |
140 | } | |
141 | } | |
142 | ||
143 | if (spool->min_hpages != -1) { /* minimum size accounting */ | |
144 | if (delta > spool->rsv_hpages) { | |
145 | /* | |
146 | * Asking for more reserves than those already taken on | |
147 | * behalf of subpool. Return difference. | |
148 | */ | |
149 | ret = delta - spool->rsv_hpages; | |
150 | spool->rsv_hpages = 0; | |
151 | } else { | |
152 | ret = 0; /* reserves already accounted for */ | |
153 | spool->rsv_hpages -= delta; | |
154 | } | |
155 | } | |
156 | ||
157 | unlock_ret: | |
158 | spin_unlock(&spool->lock); | |
159 | return ret; | |
160 | } | |
161 | ||
162 | /* | |
163 | * Subpool accounting for freeing and unreserving pages. | |
164 | * Return the number of global page reservations that must be dropped. | |
165 | * The return value may only be different than the passed value (delta) | |
166 | * in the case where a subpool minimum size must be maintained. | |
167 | */ | |
168 | static long hugepage_subpool_put_pages(struct hugepage_subpool *spool, | |
169 | long delta) | |
170 | { | |
171 | long ret = delta; | |
172 | ||
173 | if (!spool) | |
174 | return delta; | |
175 | ||
176 | spin_lock(&spool->lock); | |
177 | ||
178 | if (spool->max_hpages != -1) /* maximum size accounting */ | |
179 | spool->used_hpages -= delta; | |
180 | ||
181 | if (spool->min_hpages != -1) { /* minimum size accounting */ | |
182 | if (spool->rsv_hpages + delta <= spool->min_hpages) | |
183 | ret = 0; | |
184 | else | |
185 | ret = spool->rsv_hpages + delta - spool->min_hpages; | |
186 | ||
187 | spool->rsv_hpages += delta; | |
188 | if (spool->rsv_hpages > spool->min_hpages) | |
189 | spool->rsv_hpages = spool->min_hpages; | |
190 | } | |
191 | ||
192 | /* | |
193 | * If hugetlbfs_put_super couldn't free spool due to an outstanding | |
194 | * quota reference, free it now. | |
195 | */ | |
196 | unlock_or_release_subpool(spool); | |
197 | ||
198 | return ret; | |
199 | } | |
200 | ||
201 | static inline struct hugepage_subpool *subpool_inode(struct inode *inode) | |
202 | { | |
203 | return HUGETLBFS_SB(inode->i_sb)->spool; | |
204 | } | |
205 | ||
206 | static inline struct hugepage_subpool *subpool_vma(struct vm_area_struct *vma) | |
207 | { | |
208 | return subpool_inode(file_inode(vma->vm_file)); | |
209 | } | |
210 | ||
211 | /* | |
212 | * Region tracking -- allows tracking of reservations and instantiated pages | |
213 | * across the pages in a mapping. | |
214 | * | |
215 | * The region data structures are embedded into a resv_map and | |
216 | * protected by a resv_map's lock | |
217 | */ | |
218 | struct file_region { | |
219 | struct list_head link; | |
220 | long from; | |
221 | long to; | |
222 | }; | |
223 | ||
224 | static long region_add(struct resv_map *resv, long f, long t) | |
225 | { | |
226 | struct list_head *head = &resv->regions; | |
227 | struct file_region *rg, *nrg, *trg; | |
228 | ||
229 | spin_lock(&resv->lock); | |
230 | /* Locate the region we are either in or before. */ | |
231 | list_for_each_entry(rg, head, link) | |
232 | if (f <= rg->to) | |
233 | break; | |
234 | ||
235 | /* Round our left edge to the current segment if it encloses us. */ | |
236 | if (f > rg->from) | |
237 | f = rg->from; | |
238 | ||
239 | /* Check for and consume any regions we now overlap with. */ | |
240 | nrg = rg; | |
241 | list_for_each_entry_safe(rg, trg, rg->link.prev, link) { | |
242 | if (&rg->link == head) | |
243 | break; | |
244 | if (rg->from > t) | |
245 | break; | |
246 | ||
247 | /* If this area reaches higher then extend our area to | |
248 | * include it completely. If this is not the first area | |
249 | * which we intend to reuse, free it. */ | |
250 | if (rg->to > t) | |
251 | t = rg->to; | |
252 | if (rg != nrg) { | |
253 | list_del(&rg->link); | |
254 | kfree(rg); | |
255 | } | |
256 | } | |
257 | nrg->from = f; | |
258 | nrg->to = t; | |
259 | spin_unlock(&resv->lock); | |
260 | return 0; | |
261 | } | |
262 | ||
263 | static long region_chg(struct resv_map *resv, long f, long t) | |
264 | { | |
265 | struct list_head *head = &resv->regions; | |
266 | struct file_region *rg, *nrg = NULL; | |
267 | long chg = 0; | |
268 | ||
269 | retry: | |
270 | spin_lock(&resv->lock); | |
271 | /* Locate the region we are before or in. */ | |
272 | list_for_each_entry(rg, head, link) | |
273 | if (f <= rg->to) | |
274 | break; | |
275 | ||
276 | /* If we are below the current region then a new region is required. | |
277 | * Subtle, allocate a new region at the position but make it zero | |
278 | * size such that we can guarantee to record the reservation. */ | |
279 | if (&rg->link == head || t < rg->from) { | |
280 | if (!nrg) { | |
281 | spin_unlock(&resv->lock); | |
282 | nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); | |
283 | if (!nrg) | |
284 | return -ENOMEM; | |
285 | ||
286 | nrg->from = f; | |
287 | nrg->to = f; | |
288 | INIT_LIST_HEAD(&nrg->link); | |
289 | goto retry; | |
290 | } | |
291 | ||
292 | list_add(&nrg->link, rg->link.prev); | |
293 | chg = t - f; | |
294 | goto out_nrg; | |
295 | } | |
296 | ||
297 | /* Round our left edge to the current segment if it encloses us. */ | |
298 | if (f > rg->from) | |
299 | f = rg->from; | |
300 | chg = t - f; | |
301 | ||
302 | /* Check for and consume any regions we now overlap with. */ | |
303 | list_for_each_entry(rg, rg->link.prev, link) { | |
304 | if (&rg->link == head) | |
305 | break; | |
306 | if (rg->from > t) | |
307 | goto out; | |
308 | ||
309 | /* We overlap with this area, if it extends further than | |
310 | * us then we must extend ourselves. Account for its | |
311 | * existing reservation. */ | |
312 | if (rg->to > t) { | |
313 | chg += rg->to - t; | |
314 | t = rg->to; | |
315 | } | |
316 | chg -= rg->to - rg->from; | |
317 | } | |
318 | ||
319 | out: | |
320 | spin_unlock(&resv->lock); | |
321 | /* We already know we raced and no longer need the new region */ | |
322 | kfree(nrg); | |
323 | return chg; | |
324 | out_nrg: | |
325 | spin_unlock(&resv->lock); | |
326 | return chg; | |
327 | } | |
328 | ||
329 | static long region_truncate(struct resv_map *resv, long end) | |
330 | { | |
331 | struct list_head *head = &resv->regions; | |
332 | struct file_region *rg, *trg; | |
333 | long chg = 0; | |
334 | ||
335 | spin_lock(&resv->lock); | |
336 | /* Locate the region we are either in or before. */ | |
337 | list_for_each_entry(rg, head, link) | |
338 | if (end <= rg->to) | |
339 | break; | |
340 | if (&rg->link == head) | |
341 | goto out; | |
342 | ||
343 | /* If we are in the middle of a region then adjust it. */ | |
344 | if (end > rg->from) { | |
345 | chg = rg->to - end; | |
346 | rg->to = end; | |
347 | rg = list_entry(rg->link.next, typeof(*rg), link); | |
348 | } | |
349 | ||
350 | /* Drop any remaining regions. */ | |
351 | list_for_each_entry_safe(rg, trg, rg->link.prev, link) { | |
352 | if (&rg->link == head) | |
353 | break; | |
354 | chg += rg->to - rg->from; | |
355 | list_del(&rg->link); | |
356 | kfree(rg); | |
357 | } | |
358 | ||
359 | out: | |
360 | spin_unlock(&resv->lock); | |
361 | return chg; | |
362 | } | |
363 | ||
364 | static long region_count(struct resv_map *resv, long f, long t) | |
365 | { | |
366 | struct list_head *head = &resv->regions; | |
367 | struct file_region *rg; | |
368 | long chg = 0; | |
369 | ||
370 | spin_lock(&resv->lock); | |
371 | /* Locate each segment we overlap with, and count that overlap. */ | |
372 | list_for_each_entry(rg, head, link) { | |
373 | long seg_from; | |
374 | long seg_to; | |
375 | ||
376 | if (rg->to <= f) | |
377 | continue; | |
378 | if (rg->from >= t) | |
379 | break; | |
380 | ||
381 | seg_from = max(rg->from, f); | |
382 | seg_to = min(rg->to, t); | |
383 | ||
384 | chg += seg_to - seg_from; | |
385 | } | |
386 | spin_unlock(&resv->lock); | |
387 | ||
388 | return chg; | |
389 | } | |
390 | ||
391 | /* | |
392 | * Convert the address within this vma to the page offset within | |
393 | * the mapping, in pagecache page units; huge pages here. | |
394 | */ | |
395 | static pgoff_t vma_hugecache_offset(struct hstate *h, | |
396 | struct vm_area_struct *vma, unsigned long address) | |
397 | { | |
398 | return ((address - vma->vm_start) >> huge_page_shift(h)) + | |
399 | (vma->vm_pgoff >> huge_page_order(h)); | |
400 | } | |
401 | ||
402 | pgoff_t linear_hugepage_index(struct vm_area_struct *vma, | |
403 | unsigned long address) | |
404 | { | |
405 | return vma_hugecache_offset(hstate_vma(vma), vma, address); | |
406 | } | |
407 | ||
408 | /* | |
409 | * Return the size of the pages allocated when backing a VMA. In the majority | |
410 | * cases this will be same size as used by the page table entries. | |
411 | */ | |
412 | unsigned long vma_kernel_pagesize(struct vm_area_struct *vma) | |
413 | { | |
414 | struct hstate *hstate; | |
415 | ||
416 | if (!is_vm_hugetlb_page(vma)) | |
417 | return PAGE_SIZE; | |
418 | ||
419 | hstate = hstate_vma(vma); | |
420 | ||
421 | return 1UL << huge_page_shift(hstate); | |
422 | } | |
423 | EXPORT_SYMBOL_GPL(vma_kernel_pagesize); | |
424 | ||
425 | /* | |
426 | * Return the page size being used by the MMU to back a VMA. In the majority | |
427 | * of cases, the page size used by the kernel matches the MMU size. On | |
428 | * architectures where it differs, an architecture-specific version of this | |
429 | * function is required. | |
430 | */ | |
431 | #ifndef vma_mmu_pagesize | |
432 | unsigned long vma_mmu_pagesize(struct vm_area_struct *vma) | |
433 | { | |
434 | return vma_kernel_pagesize(vma); | |
435 | } | |
436 | #endif | |
437 | ||
438 | /* | |
439 | * Flags for MAP_PRIVATE reservations. These are stored in the bottom | |
440 | * bits of the reservation map pointer, which are always clear due to | |
441 | * alignment. | |
442 | */ | |
443 | #define HPAGE_RESV_OWNER (1UL << 0) | |
444 | #define HPAGE_RESV_UNMAPPED (1UL << 1) | |
445 | #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) | |
446 | ||
447 | /* | |
448 | * These helpers are used to track how many pages are reserved for | |
449 | * faults in a MAP_PRIVATE mapping. Only the process that called mmap() | |
450 | * is guaranteed to have their future faults succeed. | |
451 | * | |
452 | * With the exception of reset_vma_resv_huge_pages() which is called at fork(), | |
453 | * the reserve counters are updated with the hugetlb_lock held. It is safe | |
454 | * to reset the VMA at fork() time as it is not in use yet and there is no | |
455 | * chance of the global counters getting corrupted as a result of the values. | |
456 | * | |
457 | * The private mapping reservation is represented in a subtly different | |
458 | * manner to a shared mapping. A shared mapping has a region map associated | |
459 | * with the underlying file, this region map represents the backing file | |
460 | * pages which have ever had a reservation assigned which this persists even | |
461 | * after the page is instantiated. A private mapping has a region map | |
462 | * associated with the original mmap which is attached to all VMAs which | |
463 | * reference it, this region map represents those offsets which have consumed | |
464 | * reservation ie. where pages have been instantiated. | |
465 | */ | |
466 | static unsigned long get_vma_private_data(struct vm_area_struct *vma) | |
467 | { | |
468 | return (unsigned long)vma->vm_private_data; | |
469 | } | |
470 | ||
471 | static void set_vma_private_data(struct vm_area_struct *vma, | |
472 | unsigned long value) | |
473 | { | |
474 | vma->vm_private_data = (void *)value; | |
475 | } | |
476 | ||
477 | struct resv_map *resv_map_alloc(void) | |
478 | { | |
479 | struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL); | |
480 | if (!resv_map) | |
481 | return NULL; | |
482 | ||
483 | kref_init(&resv_map->refs); | |
484 | spin_lock_init(&resv_map->lock); | |
485 | INIT_LIST_HEAD(&resv_map->regions); | |
486 | ||
487 | return resv_map; | |
488 | } | |
489 | ||
490 | void resv_map_release(struct kref *ref) | |
491 | { | |
492 | struct resv_map *resv_map = container_of(ref, struct resv_map, refs); | |
493 | ||
494 | /* Clear out any active regions before we release the map. */ | |
495 | region_truncate(resv_map, 0); | |
496 | kfree(resv_map); | |
497 | } | |
498 | ||
499 | static inline struct resv_map *inode_resv_map(struct inode *inode) | |
500 | { | |
501 | return inode->i_mapping->private_data; | |
502 | } | |
503 | ||
504 | static struct resv_map *vma_resv_map(struct vm_area_struct *vma) | |
505 | { | |
506 | VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); | |
507 | if (vma->vm_flags & VM_MAYSHARE) { | |
508 | struct address_space *mapping = vma->vm_file->f_mapping; | |
509 | struct inode *inode = mapping->host; | |
510 | ||
511 | return inode_resv_map(inode); | |
512 | ||
513 | } else { | |
514 | return (struct resv_map *)(get_vma_private_data(vma) & | |
515 | ~HPAGE_RESV_MASK); | |
516 | } | |
517 | } | |
518 | ||
519 | static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map) | |
520 | { | |
521 | VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); | |
522 | VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma); | |
523 | ||
524 | set_vma_private_data(vma, (get_vma_private_data(vma) & | |
525 | HPAGE_RESV_MASK) | (unsigned long)map); | |
526 | } | |
527 | ||
528 | static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) | |
529 | { | |
530 | VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); | |
531 | VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma); | |
532 | ||
533 | set_vma_private_data(vma, get_vma_private_data(vma) | flags); | |
534 | } | |
535 | ||
536 | static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) | |
537 | { | |
538 | VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); | |
539 | ||
540 | return (get_vma_private_data(vma) & flag) != 0; | |
541 | } | |
542 | ||
543 | /* Reset counters to 0 and clear all HPAGE_RESV_* flags */ | |
544 | void reset_vma_resv_huge_pages(struct vm_area_struct *vma) | |
545 | { | |
546 | VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma); | |
547 | if (!(vma->vm_flags & VM_MAYSHARE)) | |
548 | vma->vm_private_data = (void *)0; | |
549 | } | |
550 | ||
551 | /* Returns true if the VMA has associated reserve pages */ | |
552 | static int vma_has_reserves(struct vm_area_struct *vma, long chg) | |
553 | { | |
554 | if (vma->vm_flags & VM_NORESERVE) { | |
555 | /* | |
556 | * This address is already reserved by other process(chg == 0), | |
557 | * so, we should decrement reserved count. Without decrementing, | |
558 | * reserve count remains after releasing inode, because this | |
559 | * allocated page will go into page cache and is regarded as | |
560 | * coming from reserved pool in releasing step. Currently, we | |
561 | * don't have any other solution to deal with this situation | |
562 | * properly, so add work-around here. | |
563 | */ | |
564 | if (vma->vm_flags & VM_MAYSHARE && chg == 0) | |
565 | return 1; | |
566 | else | |
567 | return 0; | |
568 | } | |
569 | ||
570 | /* Shared mappings always use reserves */ | |
571 | if (vma->vm_flags & VM_MAYSHARE) | |
572 | return 1; | |
573 | ||
574 | /* | |
575 | * Only the process that called mmap() has reserves for | |
576 | * private mappings. | |
577 | */ | |
578 | if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) | |
579 | return 1; | |
580 | ||
581 | return 0; | |
582 | } | |
583 | ||
584 | static void enqueue_huge_page(struct hstate *h, struct page *page) | |
585 | { | |
586 | int nid = page_to_nid(page); | |
587 | list_move(&page->lru, &h->hugepage_freelists[nid]); | |
588 | h->free_huge_pages++; | |
589 | h->free_huge_pages_node[nid]++; | |
590 | } | |
591 | ||
592 | static struct page *dequeue_huge_page_node(struct hstate *h, int nid) | |
593 | { | |
594 | struct page *page; | |
595 | ||
596 | list_for_each_entry(page, &h->hugepage_freelists[nid], lru) | |
597 | if (!is_migrate_isolate_page(page)) | |
598 | break; | |
599 | /* | |
600 | * if 'non-isolated free hugepage' not found on the list, | |
601 | * the allocation fails. | |
602 | */ | |
603 | if (&h->hugepage_freelists[nid] == &page->lru) | |
604 | return NULL; | |
605 | list_move(&page->lru, &h->hugepage_activelist); | |
606 | set_page_refcounted(page); | |
607 | h->free_huge_pages--; | |
608 | h->free_huge_pages_node[nid]--; | |
609 | return page; | |
610 | } | |
611 | ||
612 | /* Movability of hugepages depends on migration support. */ | |
613 | static inline gfp_t htlb_alloc_mask(struct hstate *h) | |
614 | { | |
615 | if (hugepages_treat_as_movable || hugepage_migration_supported(h)) | |
616 | return GFP_HIGHUSER_MOVABLE; | |
617 | else | |
618 | return GFP_HIGHUSER; | |
619 | } | |
620 | ||
621 | static struct page *dequeue_huge_page_vma(struct hstate *h, | |
622 | struct vm_area_struct *vma, | |
623 | unsigned long address, int avoid_reserve, | |
624 | long chg) | |
625 | { | |
626 | struct page *page = NULL; | |
627 | struct mempolicy *mpol; | |
628 | nodemask_t *nodemask; | |
629 | struct zonelist *zonelist; | |
630 | struct zone *zone; | |
631 | struct zoneref *z; | |
632 | unsigned int cpuset_mems_cookie; | |
633 | ||
634 | /* | |
635 | * A child process with MAP_PRIVATE mappings created by their parent | |
636 | * have no page reserves. This check ensures that reservations are | |
637 | * not "stolen". The child may still get SIGKILLed | |
638 | */ | |
639 | if (!vma_has_reserves(vma, chg) && | |
640 | h->free_huge_pages - h->resv_huge_pages == 0) | |
641 | goto err; | |
642 | ||
643 | /* If reserves cannot be used, ensure enough pages are in the pool */ | |
644 | if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0) | |
645 | goto err; | |
646 | ||
647 | retry_cpuset: | |
648 | cpuset_mems_cookie = read_mems_allowed_begin(); | |
649 | zonelist = huge_zonelist(vma, address, | |
650 | htlb_alloc_mask(h), &mpol, &nodemask); | |
651 | ||
652 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
653 | MAX_NR_ZONES - 1, nodemask) { | |
654 | if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) { | |
655 | page = dequeue_huge_page_node(h, zone_to_nid(zone)); | |
656 | if (page) { | |
657 | if (avoid_reserve) | |
658 | break; | |
659 | if (!vma_has_reserves(vma, chg)) | |
660 | break; | |
661 | ||
662 | SetPagePrivate(page); | |
663 | h->resv_huge_pages--; | |
664 | break; | |
665 | } | |
666 | } | |
667 | } | |
668 | ||
669 | mpol_cond_put(mpol); | |
670 | if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) | |
671 | goto retry_cpuset; | |
672 | return page; | |
673 | ||
674 | err: | |
675 | return NULL; | |
676 | } | |
677 | ||
678 | /* | |
679 | * common helper functions for hstate_next_node_to_{alloc|free}. | |
680 | * We may have allocated or freed a huge page based on a different | |
681 | * nodes_allowed previously, so h->next_node_to_{alloc|free} might | |
682 | * be outside of *nodes_allowed. Ensure that we use an allowed | |
683 | * node for alloc or free. | |
684 | */ | |
685 | static int next_node_allowed(int nid, nodemask_t *nodes_allowed) | |
686 | { | |
687 | nid = next_node(nid, *nodes_allowed); | |
688 | if (nid == MAX_NUMNODES) | |
689 | nid = first_node(*nodes_allowed); | |
690 | VM_BUG_ON(nid >= MAX_NUMNODES); | |
691 | ||
692 | return nid; | |
693 | } | |
694 | ||
695 | static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed) | |
696 | { | |
697 | if (!node_isset(nid, *nodes_allowed)) | |
698 | nid = next_node_allowed(nid, nodes_allowed); | |
699 | return nid; | |
700 | } | |
701 | ||
702 | /* | |
703 | * returns the previously saved node ["this node"] from which to | |
704 | * allocate a persistent huge page for the pool and advance the | |
705 | * next node from which to allocate, handling wrap at end of node | |
706 | * mask. | |
707 | */ | |
708 | static int hstate_next_node_to_alloc(struct hstate *h, | |
709 | nodemask_t *nodes_allowed) | |
710 | { | |
711 | int nid; | |
712 | ||
713 | VM_BUG_ON(!nodes_allowed); | |
714 | ||
715 | nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed); | |
716 | h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed); | |
717 | ||
718 | return nid; | |
719 | } | |
720 | ||
721 | /* | |
722 | * helper for free_pool_huge_page() - return the previously saved | |
723 | * node ["this node"] from which to free a huge page. Advance the | |
724 | * next node id whether or not we find a free huge page to free so | |
725 | * that the next attempt to free addresses the next node. | |
726 | */ | |
727 | static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) | |
728 | { | |
729 | int nid; | |
730 | ||
731 | VM_BUG_ON(!nodes_allowed); | |
732 | ||
733 | nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed); | |
734 | h->next_nid_to_free = next_node_allowed(nid, nodes_allowed); | |
735 | ||
736 | return nid; | |
737 | } | |
738 | ||
739 | #define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \ | |
740 | for (nr_nodes = nodes_weight(*mask); \ | |
741 | nr_nodes > 0 && \ | |
742 | ((node = hstate_next_node_to_alloc(hs, mask)) || 1); \ | |
743 | nr_nodes--) | |
744 | ||
745 | #define for_each_node_mask_to_free(hs, nr_nodes, node, mask) \ | |
746 | for (nr_nodes = nodes_weight(*mask); \ | |
747 | nr_nodes > 0 && \ | |
748 | ((node = hstate_next_node_to_free(hs, mask)) || 1); \ | |
749 | nr_nodes--) | |
750 | ||
751 | #if defined(CONFIG_CMA) && defined(CONFIG_X86_64) | |
752 | static void destroy_compound_gigantic_page(struct page *page, | |
753 | unsigned long order) | |
754 | { | |
755 | int i; | |
756 | int nr_pages = 1 << order; | |
757 | struct page *p = page + 1; | |
758 | ||
759 | for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { | |
760 | __ClearPageTail(p); | |
761 | set_page_refcounted(p); | |
762 | p->first_page = NULL; | |
763 | } | |
764 | ||
765 | set_compound_order(page, 0); | |
766 | __ClearPageHead(page); | |
767 | } | |
768 | ||
769 | static void free_gigantic_page(struct page *page, unsigned order) | |
770 | { | |
771 | free_contig_range(page_to_pfn(page), 1 << order); | |
772 | } | |
773 | ||
774 | static int __alloc_gigantic_page(unsigned long start_pfn, | |
775 | unsigned long nr_pages) | |
776 | { | |
777 | unsigned long end_pfn = start_pfn + nr_pages; | |
778 | return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE); | |
779 | } | |
780 | ||
781 | static bool pfn_range_valid_gigantic(unsigned long start_pfn, | |
782 | unsigned long nr_pages) | |
783 | { | |
784 | unsigned long i, end_pfn = start_pfn + nr_pages; | |
785 | struct page *page; | |
786 | ||
787 | for (i = start_pfn; i < end_pfn; i++) { | |
788 | if (!pfn_valid(i)) | |
789 | return false; | |
790 | ||
791 | page = pfn_to_page(i); | |
792 | ||
793 | if (PageReserved(page)) | |
794 | return false; | |
795 | ||
796 | if (page_count(page) > 0) | |
797 | return false; | |
798 | ||
799 | if (PageHuge(page)) | |
800 | return false; | |
801 | } | |
802 | ||
803 | return true; | |
804 | } | |
805 | ||
806 | static bool zone_spans_last_pfn(const struct zone *zone, | |
807 | unsigned long start_pfn, unsigned long nr_pages) | |
808 | { | |
809 | unsigned long last_pfn = start_pfn + nr_pages - 1; | |
810 | return zone_spans_pfn(zone, last_pfn); | |
811 | } | |
812 | ||
813 | static struct page *alloc_gigantic_page(int nid, unsigned order) | |
814 | { | |
815 | unsigned long nr_pages = 1 << order; | |
816 | unsigned long ret, pfn, flags; | |
817 | struct zone *z; | |
818 | ||
819 | z = NODE_DATA(nid)->node_zones; | |
820 | for (; z - NODE_DATA(nid)->node_zones < MAX_NR_ZONES; z++) { | |
821 | spin_lock_irqsave(&z->lock, flags); | |
822 | ||
823 | pfn = ALIGN(z->zone_start_pfn, nr_pages); | |
824 | while (zone_spans_last_pfn(z, pfn, nr_pages)) { | |
825 | if (pfn_range_valid_gigantic(pfn, nr_pages)) { | |
826 | /* | |
827 | * We release the zone lock here because | |
828 | * alloc_contig_range() will also lock the zone | |
829 | * at some point. If there's an allocation | |
830 | * spinning on this lock, it may win the race | |
831 | * and cause alloc_contig_range() to fail... | |
832 | */ | |
833 | spin_unlock_irqrestore(&z->lock, flags); | |
834 | ret = __alloc_gigantic_page(pfn, nr_pages); | |
835 | if (!ret) | |
836 | return pfn_to_page(pfn); | |
837 | spin_lock_irqsave(&z->lock, flags); | |
838 | } | |
839 | pfn += nr_pages; | |
840 | } | |
841 | ||
842 | spin_unlock_irqrestore(&z->lock, flags); | |
843 | } | |
844 | ||
845 | return NULL; | |
846 | } | |
847 | ||
848 | static void prep_new_huge_page(struct hstate *h, struct page *page, int nid); | |
849 | static void prep_compound_gigantic_page(struct page *page, unsigned long order); | |
850 | ||
851 | static struct page *alloc_fresh_gigantic_page_node(struct hstate *h, int nid) | |
852 | { | |
853 | struct page *page; | |
854 | ||
855 | page = alloc_gigantic_page(nid, huge_page_order(h)); | |
856 | if (page) { | |
857 | prep_compound_gigantic_page(page, huge_page_order(h)); | |
858 | prep_new_huge_page(h, page, nid); | |
859 | } | |
860 | ||
861 | return page; | |
862 | } | |
863 | ||
864 | static int alloc_fresh_gigantic_page(struct hstate *h, | |
865 | nodemask_t *nodes_allowed) | |
866 | { | |
867 | struct page *page = NULL; | |
868 | int nr_nodes, node; | |
869 | ||
870 | for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) { | |
871 | page = alloc_fresh_gigantic_page_node(h, node); | |
872 | if (page) | |
873 | return 1; | |
874 | } | |
875 | ||
876 | return 0; | |
877 | } | |
878 | ||
879 | static inline bool gigantic_page_supported(void) { return true; } | |
880 | #else | |
881 | static inline bool gigantic_page_supported(void) { return false; } | |
882 | static inline void free_gigantic_page(struct page *page, unsigned order) { } | |
883 | static inline void destroy_compound_gigantic_page(struct page *page, | |
884 | unsigned long order) { } | |
885 | static inline int alloc_fresh_gigantic_page(struct hstate *h, | |
886 | nodemask_t *nodes_allowed) { return 0; } | |
887 | #endif | |
888 | ||
889 | static void update_and_free_page(struct hstate *h, struct page *page) | |
890 | { | |
891 | int i; | |
892 | ||
893 | if (hstate_is_gigantic(h) && !gigantic_page_supported()) | |
894 | return; | |
895 | ||
896 | h->nr_huge_pages--; | |
897 | h->nr_huge_pages_node[page_to_nid(page)]--; | |
898 | for (i = 0; i < pages_per_huge_page(h); i++) { | |
899 | page[i].flags &= ~(1 << PG_locked | 1 << PG_error | | |
900 | 1 << PG_referenced | 1 << PG_dirty | | |
901 | 1 << PG_active | 1 << PG_private | | |
902 | 1 << PG_writeback); | |
903 | } | |
904 | VM_BUG_ON_PAGE(hugetlb_cgroup_from_page(page), page); | |
905 | set_compound_page_dtor(page, NULL); | |
906 | set_page_refcounted(page); | |
907 | if (hstate_is_gigantic(h)) { | |
908 | destroy_compound_gigantic_page(page, huge_page_order(h)); | |
909 | free_gigantic_page(page, huge_page_order(h)); | |
910 | } else { | |
911 | arch_release_hugepage(page); | |
912 | __free_pages(page, huge_page_order(h)); | |
913 | } | |
914 | } | |
915 | ||
916 | struct hstate *size_to_hstate(unsigned long size) | |
917 | { | |
918 | struct hstate *h; | |
919 | ||
920 | for_each_hstate(h) { | |
921 | if (huge_page_size(h) == size) | |
922 | return h; | |
923 | } | |
924 | return NULL; | |
925 | } | |
926 | ||
927 | void free_huge_page(struct page *page) | |
928 | { | |
929 | /* | |
930 | * Can't pass hstate in here because it is called from the | |
931 | * compound page destructor. | |
932 | */ | |
933 | struct hstate *h = page_hstate(page); | |
934 | int nid = page_to_nid(page); | |
935 | struct hugepage_subpool *spool = | |
936 | (struct hugepage_subpool *)page_private(page); | |
937 | bool restore_reserve; | |
938 | ||
939 | set_page_private(page, 0); | |
940 | page->mapping = NULL; | |
941 | BUG_ON(page_count(page)); | |
942 | BUG_ON(page_mapcount(page)); | |
943 | restore_reserve = PagePrivate(page); | |
944 | ClearPagePrivate(page); | |
945 | ||
946 | /* | |
947 | * A return code of zero implies that the subpool will be under its | |
948 | * minimum size if the reservation is not restored after page is free. | |
949 | * Therefore, force restore_reserve operation. | |
950 | */ | |
951 | if (hugepage_subpool_put_pages(spool, 1) == 0) | |
952 | restore_reserve = true; | |
953 | ||
954 | spin_lock(&hugetlb_lock); | |
955 | hugetlb_cgroup_uncharge_page(hstate_index(h), | |
956 | pages_per_huge_page(h), page); | |
957 | if (restore_reserve) | |
958 | h->resv_huge_pages++; | |
959 | ||
960 | if (h->surplus_huge_pages_node[nid]) { | |
961 | /* remove the page from active list */ | |
962 | list_del(&page->lru); | |
963 | update_and_free_page(h, page); | |
964 | h->surplus_huge_pages--; | |
965 | h->surplus_huge_pages_node[nid]--; | |
966 | } else { | |
967 | arch_clear_hugepage_flags(page); | |
968 | enqueue_huge_page(h, page); | |
969 | } | |
970 | spin_unlock(&hugetlb_lock); | |
971 | } | |
972 | ||
973 | static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) | |
974 | { | |
975 | INIT_LIST_HEAD(&page->lru); | |
976 | set_compound_page_dtor(page, free_huge_page); | |
977 | spin_lock(&hugetlb_lock); | |
978 | set_hugetlb_cgroup(page, NULL); | |
979 | h->nr_huge_pages++; | |
980 | h->nr_huge_pages_node[nid]++; | |
981 | spin_unlock(&hugetlb_lock); | |
982 | put_page(page); /* free it into the hugepage allocator */ | |
983 | } | |
984 | ||
985 | static void prep_compound_gigantic_page(struct page *page, unsigned long order) | |
986 | { | |
987 | int i; | |
988 | int nr_pages = 1 << order; | |
989 | struct page *p = page + 1; | |
990 | ||
991 | /* we rely on prep_new_huge_page to set the destructor */ | |
992 | set_compound_order(page, order); | |
993 | __SetPageHead(page); | |
994 | __ClearPageReserved(page); | |
995 | for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { | |
996 | /* | |
997 | * For gigantic hugepages allocated through bootmem at | |
998 | * boot, it's safer to be consistent with the not-gigantic | |
999 | * hugepages and clear the PG_reserved bit from all tail pages | |
1000 | * too. Otherwse drivers using get_user_pages() to access tail | |
1001 | * pages may get the reference counting wrong if they see | |
1002 | * PG_reserved set on a tail page (despite the head page not | |
1003 | * having PG_reserved set). Enforcing this consistency between | |
1004 | * head and tail pages allows drivers to optimize away a check | |
1005 | * on the head page when they need know if put_page() is needed | |
1006 | * after get_user_pages(). | |
1007 | */ | |
1008 | __ClearPageReserved(p); | |
1009 | set_page_count(p, 0); | |
1010 | p->first_page = page; | |
1011 | /* Make sure p->first_page is always valid for PageTail() */ | |
1012 | smp_wmb(); | |
1013 | __SetPageTail(p); | |
1014 | } | |
1015 | } | |
1016 | ||
1017 | /* | |
1018 | * PageHuge() only returns true for hugetlbfs pages, but not for normal or | |
1019 | * transparent huge pages. See the PageTransHuge() documentation for more | |
1020 | * details. | |
1021 | */ | |
1022 | int PageHuge(struct page *page) | |
1023 | { | |
1024 | if (!PageCompound(page)) | |
1025 | return 0; | |
1026 | ||
1027 | page = compound_head(page); | |
1028 | return get_compound_page_dtor(page) == free_huge_page; | |
1029 | } | |
1030 | EXPORT_SYMBOL_GPL(PageHuge); | |
1031 | ||
1032 | /* | |
1033 | * PageHeadHuge() only returns true for hugetlbfs head page, but not for | |
1034 | * normal or transparent huge pages. | |
1035 | */ | |
1036 | int PageHeadHuge(struct page *page_head) | |
1037 | { | |
1038 | if (!PageHead(page_head)) | |
1039 | return 0; | |
1040 | ||
1041 | return get_compound_page_dtor(page_head) == free_huge_page; | |
1042 | } | |
1043 | ||
1044 | pgoff_t __basepage_index(struct page *page) | |
1045 | { | |
1046 | struct page *page_head = compound_head(page); | |
1047 | pgoff_t index = page_index(page_head); | |
1048 | unsigned long compound_idx; | |
1049 | ||
1050 | if (!PageHuge(page_head)) | |
1051 | return page_index(page); | |
1052 | ||
1053 | if (compound_order(page_head) >= MAX_ORDER) | |
1054 | compound_idx = page_to_pfn(page) - page_to_pfn(page_head); | |
1055 | else | |
1056 | compound_idx = page - page_head; | |
1057 | ||
1058 | return (index << compound_order(page_head)) + compound_idx; | |
1059 | } | |
1060 | ||
1061 | static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) | |
1062 | { | |
1063 | struct page *page; | |
1064 | ||
1065 | page = alloc_pages_exact_node(nid, | |
1066 | htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE| | |
1067 | __GFP_REPEAT|__GFP_NOWARN, | |
1068 | huge_page_order(h)); | |
1069 | if (page) { | |
1070 | if (arch_prepare_hugepage(page)) { | |
1071 | __free_pages(page, huge_page_order(h)); | |
1072 | return NULL; | |
1073 | } | |
1074 | prep_new_huge_page(h, page, nid); | |
1075 | } | |
1076 | ||
1077 | return page; | |
1078 | } | |
1079 | ||
1080 | static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed) | |
1081 | { | |
1082 | struct page *page; | |
1083 | int nr_nodes, node; | |
1084 | int ret = 0; | |
1085 | ||
1086 | for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) { | |
1087 | page = alloc_fresh_huge_page_node(h, node); | |
1088 | if (page) { | |
1089 | ret = 1; | |
1090 | break; | |
1091 | } | |
1092 | } | |
1093 | ||
1094 | if (ret) | |
1095 | count_vm_event(HTLB_BUDDY_PGALLOC); | |
1096 | else | |
1097 | count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); | |
1098 | ||
1099 | return ret; | |
1100 | } | |
1101 | ||
1102 | /* | |
1103 | * Free huge page from pool from next node to free. | |
1104 | * Attempt to keep persistent huge pages more or less | |
1105 | * balanced over allowed nodes. | |
1106 | * Called with hugetlb_lock locked. | |
1107 | */ | |
1108 | static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, | |
1109 | bool acct_surplus) | |
1110 | { | |
1111 | int nr_nodes, node; | |
1112 | int ret = 0; | |
1113 | ||
1114 | for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { | |
1115 | /* | |
1116 | * If we're returning unused surplus pages, only examine | |
1117 | * nodes with surplus pages. | |
1118 | */ | |
1119 | if ((!acct_surplus || h->surplus_huge_pages_node[node]) && | |
1120 | !list_empty(&h->hugepage_freelists[node])) { | |
1121 | struct page *page = | |
1122 | list_entry(h->hugepage_freelists[node].next, | |
1123 | struct page, lru); | |
1124 | list_del(&page->lru); | |
1125 | h->free_huge_pages--; | |
1126 | h->free_huge_pages_node[node]--; | |
1127 | if (acct_surplus) { | |
1128 | h->surplus_huge_pages--; | |
1129 | h->surplus_huge_pages_node[node]--; | |
1130 | } | |
1131 | update_and_free_page(h, page); | |
1132 | ret = 1; | |
1133 | break; | |
1134 | } | |
1135 | } | |
1136 | ||
1137 | return ret; | |
1138 | } | |
1139 | ||
1140 | /* | |
1141 | * Dissolve a given free hugepage into free buddy pages. This function does | |
1142 | * nothing for in-use (including surplus) hugepages. | |
1143 | */ | |
1144 | static void dissolve_free_huge_page(struct page *page) | |
1145 | { | |
1146 | spin_lock(&hugetlb_lock); | |
1147 | if (PageHuge(page) && !page_count(page)) { | |
1148 | struct hstate *h = page_hstate(page); | |
1149 | int nid = page_to_nid(page); | |
1150 | list_del(&page->lru); | |
1151 | h->free_huge_pages--; | |
1152 | h->free_huge_pages_node[nid]--; | |
1153 | update_and_free_page(h, page); | |
1154 | } | |
1155 | spin_unlock(&hugetlb_lock); | |
1156 | } | |
1157 | ||
1158 | /* | |
1159 | * Dissolve free hugepages in a given pfn range. Used by memory hotplug to | |
1160 | * make specified memory blocks removable from the system. | |
1161 | * Note that start_pfn should aligned with (minimum) hugepage size. | |
1162 | */ | |
1163 | void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn) | |
1164 | { | |
1165 | unsigned int order = 8 * sizeof(void *); | |
1166 | unsigned long pfn; | |
1167 | struct hstate *h; | |
1168 | ||
1169 | if (!hugepages_supported()) | |
1170 | return; | |
1171 | ||
1172 | /* Set scan step to minimum hugepage size */ | |
1173 | for_each_hstate(h) | |
1174 | if (order > huge_page_order(h)) | |
1175 | order = huge_page_order(h); | |
1176 | VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << order)); | |
1177 | for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) | |
1178 | dissolve_free_huge_page(pfn_to_page(pfn)); | |
1179 | } | |
1180 | ||
1181 | static struct page *alloc_buddy_huge_page(struct hstate *h, int nid) | |
1182 | { | |
1183 | struct page *page; | |
1184 | unsigned int r_nid; | |
1185 | ||
1186 | if (hstate_is_gigantic(h)) | |
1187 | return NULL; | |
1188 | ||
1189 | /* | |
1190 | * Assume we will successfully allocate the surplus page to | |
1191 | * prevent racing processes from causing the surplus to exceed | |
1192 | * overcommit | |
1193 | * | |
1194 | * This however introduces a different race, where a process B | |
1195 | * tries to grow the static hugepage pool while alloc_pages() is | |
1196 | * called by process A. B will only examine the per-node | |
1197 | * counters in determining if surplus huge pages can be | |
1198 | * converted to normal huge pages in adjust_pool_surplus(). A | |
1199 | * won't be able to increment the per-node counter, until the | |
1200 | * lock is dropped by B, but B doesn't drop hugetlb_lock until | |
1201 | * no more huge pages can be converted from surplus to normal | |
1202 | * state (and doesn't try to convert again). Thus, we have a | |
1203 | * case where a surplus huge page exists, the pool is grown, and | |
1204 | * the surplus huge page still exists after, even though it | |
1205 | * should just have been converted to a normal huge page. This | |
1206 | * does not leak memory, though, as the hugepage will be freed | |
1207 | * once it is out of use. It also does not allow the counters to | |
1208 | * go out of whack in adjust_pool_surplus() as we don't modify | |
1209 | * the node values until we've gotten the hugepage and only the | |
1210 | * per-node value is checked there. | |
1211 | */ | |
1212 | spin_lock(&hugetlb_lock); | |
1213 | if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) { | |
1214 | spin_unlock(&hugetlb_lock); | |
1215 | return NULL; | |
1216 | } else { | |
1217 | h->nr_huge_pages++; | |
1218 | h->surplus_huge_pages++; | |
1219 | } | |
1220 | spin_unlock(&hugetlb_lock); | |
1221 | ||
1222 | if (nid == NUMA_NO_NODE) | |
1223 | page = alloc_pages(htlb_alloc_mask(h)|__GFP_COMP| | |
1224 | __GFP_REPEAT|__GFP_NOWARN, | |
1225 | huge_page_order(h)); | |
1226 | else | |
1227 | page = alloc_pages_exact_node(nid, | |
1228 | htlb_alloc_mask(h)|__GFP_COMP|__GFP_THISNODE| | |
1229 | __GFP_REPEAT|__GFP_NOWARN, huge_page_order(h)); | |
1230 | ||
1231 | if (page && arch_prepare_hugepage(page)) { | |
1232 | __free_pages(page, huge_page_order(h)); | |
1233 | page = NULL; | |
1234 | } | |
1235 | ||
1236 | spin_lock(&hugetlb_lock); | |
1237 | if (page) { | |
1238 | INIT_LIST_HEAD(&page->lru); | |
1239 | r_nid = page_to_nid(page); | |
1240 | set_compound_page_dtor(page, free_huge_page); | |
1241 | set_hugetlb_cgroup(page, NULL); | |
1242 | /* | |
1243 | * We incremented the global counters already | |
1244 | */ | |
1245 | h->nr_huge_pages_node[r_nid]++; | |
1246 | h->surplus_huge_pages_node[r_nid]++; | |
1247 | __count_vm_event(HTLB_BUDDY_PGALLOC); | |
1248 | } else { | |
1249 | h->nr_huge_pages--; | |
1250 | h->surplus_huge_pages--; | |
1251 | __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); | |
1252 | } | |
1253 | spin_unlock(&hugetlb_lock); | |
1254 | ||
1255 | return page; | |
1256 | } | |
1257 | ||
1258 | /* | |
1259 | * This allocation function is useful in the context where vma is irrelevant. | |
1260 | * E.g. soft-offlining uses this function because it only cares physical | |
1261 | * address of error page. | |
1262 | */ | |
1263 | struct page *alloc_huge_page_node(struct hstate *h, int nid) | |
1264 | { | |
1265 | struct page *page = NULL; | |
1266 | ||
1267 | spin_lock(&hugetlb_lock); | |
1268 | if (h->free_huge_pages - h->resv_huge_pages > 0) | |
1269 | page = dequeue_huge_page_node(h, nid); | |
1270 | spin_unlock(&hugetlb_lock); | |
1271 | ||
1272 | if (!page) | |
1273 | page = alloc_buddy_huge_page(h, nid); | |
1274 | ||
1275 | return page; | |
1276 | } | |
1277 | ||
1278 | /* | |
1279 | * Increase the hugetlb pool such that it can accommodate a reservation | |
1280 | * of size 'delta'. | |
1281 | */ | |
1282 | static int gather_surplus_pages(struct hstate *h, int delta) | |
1283 | { | |
1284 | struct list_head surplus_list; | |
1285 | struct page *page, *tmp; | |
1286 | int ret, i; | |
1287 | int needed, allocated; | |
1288 | bool alloc_ok = true; | |
1289 | ||
1290 | needed = (h->resv_huge_pages + delta) - h->free_huge_pages; | |
1291 | if (needed <= 0) { | |
1292 | h->resv_huge_pages += delta; | |
1293 | return 0; | |
1294 | } | |
1295 | ||
1296 | allocated = 0; | |
1297 | INIT_LIST_HEAD(&surplus_list); | |
1298 | ||
1299 | ret = -ENOMEM; | |
1300 | retry: | |
1301 | spin_unlock(&hugetlb_lock); | |
1302 | for (i = 0; i < needed; i++) { | |
1303 | page = alloc_buddy_huge_page(h, NUMA_NO_NODE); | |
1304 | if (!page) { | |
1305 | alloc_ok = false; | |
1306 | break; | |
1307 | } | |
1308 | list_add(&page->lru, &surplus_list); | |
1309 | } | |
1310 | allocated += i; | |
1311 | ||
1312 | /* | |
1313 | * After retaking hugetlb_lock, we need to recalculate 'needed' | |
1314 | * because either resv_huge_pages or free_huge_pages may have changed. | |
1315 | */ | |
1316 | spin_lock(&hugetlb_lock); | |
1317 | needed = (h->resv_huge_pages + delta) - | |
1318 | (h->free_huge_pages + allocated); | |
1319 | if (needed > 0) { | |
1320 | if (alloc_ok) | |
1321 | goto retry; | |
1322 | /* | |
1323 | * We were not able to allocate enough pages to | |
1324 | * satisfy the entire reservation so we free what | |
1325 | * we've allocated so far. | |
1326 | */ | |
1327 | goto free; | |
1328 | } | |
1329 | /* | |
1330 | * The surplus_list now contains _at_least_ the number of extra pages | |
1331 | * needed to accommodate the reservation. Add the appropriate number | |
1332 | * of pages to the hugetlb pool and free the extras back to the buddy | |
1333 | * allocator. Commit the entire reservation here to prevent another | |
1334 | * process from stealing the pages as they are added to the pool but | |
1335 | * before they are reserved. | |
1336 | */ | |
1337 | needed += allocated; | |
1338 | h->resv_huge_pages += delta; | |
1339 | ret = 0; | |
1340 | ||
1341 | /* Free the needed pages to the hugetlb pool */ | |
1342 | list_for_each_entry_safe(page, tmp, &surplus_list, lru) { | |
1343 | if ((--needed) < 0) | |
1344 | break; | |
1345 | /* | |
1346 | * This page is now managed by the hugetlb allocator and has | |
1347 | * no users -- drop the buddy allocator's reference. | |
1348 | */ | |
1349 | put_page_testzero(page); | |
1350 | VM_BUG_ON_PAGE(page_count(page), page); | |
1351 | enqueue_huge_page(h, page); | |
1352 | } | |
1353 | free: | |
1354 | spin_unlock(&hugetlb_lock); | |
1355 | ||
1356 | /* Free unnecessary surplus pages to the buddy allocator */ | |
1357 | list_for_each_entry_safe(page, tmp, &surplus_list, lru) | |
1358 | put_page(page); | |
1359 | spin_lock(&hugetlb_lock); | |
1360 | ||
1361 | return ret; | |
1362 | } | |
1363 | ||
1364 | /* | |
1365 | * When releasing a hugetlb pool reservation, any surplus pages that were | |
1366 | * allocated to satisfy the reservation must be explicitly freed if they were | |
1367 | * never used. | |
1368 | * Called with hugetlb_lock held. | |
1369 | */ | |
1370 | static void return_unused_surplus_pages(struct hstate *h, | |
1371 | unsigned long unused_resv_pages) | |
1372 | { | |
1373 | unsigned long nr_pages; | |
1374 | ||
1375 | /* Uncommit the reservation */ | |
1376 | h->resv_huge_pages -= unused_resv_pages; | |
1377 | ||
1378 | /* Cannot return gigantic pages currently */ | |
1379 | if (hstate_is_gigantic(h)) | |
1380 | return; | |
1381 | ||
1382 | nr_pages = min(unused_resv_pages, h->surplus_huge_pages); | |
1383 | ||
1384 | /* | |
1385 | * We want to release as many surplus pages as possible, spread | |
1386 | * evenly across all nodes with memory. Iterate across these nodes | |
1387 | * until we can no longer free unreserved surplus pages. This occurs | |
1388 | * when the nodes with surplus pages have no free pages. | |
1389 | * free_pool_huge_page() will balance the the freed pages across the | |
1390 | * on-line nodes with memory and will handle the hstate accounting. | |
1391 | */ | |
1392 | while (nr_pages--) { | |
1393 | if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1)) | |
1394 | break; | |
1395 | cond_resched_lock(&hugetlb_lock); | |
1396 | } | |
1397 | } | |
1398 | ||
1399 | /* | |
1400 | * Determine if the huge page at addr within the vma has an associated | |
1401 | * reservation. Where it does not we will need to logically increase | |
1402 | * reservation and actually increase subpool usage before an allocation | |
1403 | * can occur. Where any new reservation would be required the | |
1404 | * reservation change is prepared, but not committed. Once the page | |
1405 | * has been allocated from the subpool and instantiated the change should | |
1406 | * be committed via vma_commit_reservation. No action is required on | |
1407 | * failure. | |
1408 | */ | |
1409 | static long vma_needs_reservation(struct hstate *h, | |
1410 | struct vm_area_struct *vma, unsigned long addr) | |
1411 | { | |
1412 | struct resv_map *resv; | |
1413 | pgoff_t idx; | |
1414 | long chg; | |
1415 | ||
1416 | resv = vma_resv_map(vma); | |
1417 | if (!resv) | |
1418 | return 1; | |
1419 | ||
1420 | idx = vma_hugecache_offset(h, vma, addr); | |
1421 | chg = region_chg(resv, idx, idx + 1); | |
1422 | ||
1423 | if (vma->vm_flags & VM_MAYSHARE) | |
1424 | return chg; | |
1425 | else | |
1426 | return chg < 0 ? chg : 0; | |
1427 | } | |
1428 | static void vma_commit_reservation(struct hstate *h, | |
1429 | struct vm_area_struct *vma, unsigned long addr) | |
1430 | { | |
1431 | struct resv_map *resv; | |
1432 | pgoff_t idx; | |
1433 | ||
1434 | resv = vma_resv_map(vma); | |
1435 | if (!resv) | |
1436 | return; | |
1437 | ||
1438 | idx = vma_hugecache_offset(h, vma, addr); | |
1439 | region_add(resv, idx, idx + 1); | |
1440 | } | |
1441 | ||
1442 | static struct page *alloc_huge_page(struct vm_area_struct *vma, | |
1443 | unsigned long addr, int avoid_reserve) | |
1444 | { | |
1445 | struct hugepage_subpool *spool = subpool_vma(vma); | |
1446 | struct hstate *h = hstate_vma(vma); | |
1447 | struct page *page; | |
1448 | long chg; | |
1449 | int ret, idx; | |
1450 | struct hugetlb_cgroup *h_cg; | |
1451 | ||
1452 | idx = hstate_index(h); | |
1453 | /* | |
1454 | * Processes that did not create the mapping will have no | |
1455 | * reserves and will not have accounted against subpool | |
1456 | * limit. Check that the subpool limit can be made before | |
1457 | * satisfying the allocation MAP_NORESERVE mappings may also | |
1458 | * need pages and subpool limit allocated allocated if no reserve | |
1459 | * mapping overlaps. | |
1460 | */ | |
1461 | chg = vma_needs_reservation(h, vma, addr); | |
1462 | if (chg < 0) | |
1463 | return ERR_PTR(-ENOMEM); | |
1464 | if (chg || avoid_reserve) | |
1465 | if (hugepage_subpool_get_pages(spool, 1) < 0) | |
1466 | return ERR_PTR(-ENOSPC); | |
1467 | ||
1468 | ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg); | |
1469 | if (ret) | |
1470 | goto out_subpool_put; | |
1471 | ||
1472 | spin_lock(&hugetlb_lock); | |
1473 | page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, chg); | |
1474 | if (!page) { | |
1475 | spin_unlock(&hugetlb_lock); | |
1476 | page = alloc_buddy_huge_page(h, NUMA_NO_NODE); | |
1477 | if (!page) | |
1478 | goto out_uncharge_cgroup; | |
1479 | ||
1480 | spin_lock(&hugetlb_lock); | |
1481 | list_move(&page->lru, &h->hugepage_activelist); | |
1482 | /* Fall through */ | |
1483 | } | |
1484 | hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page); | |
1485 | spin_unlock(&hugetlb_lock); | |
1486 | ||
1487 | set_page_private(page, (unsigned long)spool); | |
1488 | ||
1489 | vma_commit_reservation(h, vma, addr); | |
1490 | return page; | |
1491 | ||
1492 | out_uncharge_cgroup: | |
1493 | hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg); | |
1494 | out_subpool_put: | |
1495 | if (chg || avoid_reserve) | |
1496 | hugepage_subpool_put_pages(spool, 1); | |
1497 | return ERR_PTR(-ENOSPC); | |
1498 | } | |
1499 | ||
1500 | /* | |
1501 | * alloc_huge_page()'s wrapper which simply returns the page if allocation | |
1502 | * succeeds, otherwise NULL. This function is called from new_vma_page(), | |
1503 | * where no ERR_VALUE is expected to be returned. | |
1504 | */ | |
1505 | struct page *alloc_huge_page_noerr(struct vm_area_struct *vma, | |
1506 | unsigned long addr, int avoid_reserve) | |
1507 | { | |
1508 | struct page *page = alloc_huge_page(vma, addr, avoid_reserve); | |
1509 | if (IS_ERR(page)) | |
1510 | page = NULL; | |
1511 | return page; | |
1512 | } | |
1513 | ||
1514 | int __weak alloc_bootmem_huge_page(struct hstate *h) | |
1515 | { | |
1516 | struct huge_bootmem_page *m; | |
1517 | int nr_nodes, node; | |
1518 | ||
1519 | for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) { | |
1520 | void *addr; | |
1521 | ||
1522 | addr = memblock_virt_alloc_try_nid_nopanic( | |
1523 | huge_page_size(h), huge_page_size(h), | |
1524 | 0, BOOTMEM_ALLOC_ACCESSIBLE, node); | |
1525 | if (addr) { | |
1526 | /* | |
1527 | * Use the beginning of the huge page to store the | |
1528 | * huge_bootmem_page struct (until gather_bootmem | |
1529 | * puts them into the mem_map). | |
1530 | */ | |
1531 | m = addr; | |
1532 | goto found; | |
1533 | } | |
1534 | } | |
1535 | return 0; | |
1536 | ||
1537 | found: | |
1538 | BUG_ON(!IS_ALIGNED(virt_to_phys(m), huge_page_size(h))); | |
1539 | /* Put them into a private list first because mem_map is not up yet */ | |
1540 | list_add(&m->list, &huge_boot_pages); | |
1541 | m->hstate = h; | |
1542 | return 1; | |
1543 | } | |
1544 | ||
1545 | static void __init prep_compound_huge_page(struct page *page, int order) | |
1546 | { | |
1547 | if (unlikely(order > (MAX_ORDER - 1))) | |
1548 | prep_compound_gigantic_page(page, order); | |
1549 | else | |
1550 | prep_compound_page(page, order); | |
1551 | } | |
1552 | ||
1553 | /* Put bootmem huge pages into the standard lists after mem_map is up */ | |
1554 | static void __init gather_bootmem_prealloc(void) | |
1555 | { | |
1556 | struct huge_bootmem_page *m; | |
1557 | ||
1558 | list_for_each_entry(m, &huge_boot_pages, list) { | |
1559 | struct hstate *h = m->hstate; | |
1560 | struct page *page; | |
1561 | ||
1562 | #ifdef CONFIG_HIGHMEM | |
1563 | page = pfn_to_page(m->phys >> PAGE_SHIFT); | |
1564 | memblock_free_late(__pa(m), | |
1565 | sizeof(struct huge_bootmem_page)); | |
1566 | #else | |
1567 | page = virt_to_page(m); | |
1568 | #endif | |
1569 | WARN_ON(page_count(page) != 1); | |
1570 | prep_compound_huge_page(page, h->order); | |
1571 | WARN_ON(PageReserved(page)); | |
1572 | prep_new_huge_page(h, page, page_to_nid(page)); | |
1573 | /* | |
1574 | * If we had gigantic hugepages allocated at boot time, we need | |
1575 | * to restore the 'stolen' pages to totalram_pages in order to | |
1576 | * fix confusing memory reports from free(1) and another | |
1577 | * side-effects, like CommitLimit going negative. | |
1578 | */ | |
1579 | if (hstate_is_gigantic(h)) | |
1580 | adjust_managed_page_count(page, 1 << h->order); | |
1581 | } | |
1582 | } | |
1583 | ||
1584 | static void __init hugetlb_hstate_alloc_pages(struct hstate *h) | |
1585 | { | |
1586 | unsigned long i; | |
1587 | ||
1588 | for (i = 0; i < h->max_huge_pages; ++i) { | |
1589 | if (hstate_is_gigantic(h)) { | |
1590 | if (!alloc_bootmem_huge_page(h)) | |
1591 | break; | |
1592 | } else if (!alloc_fresh_huge_page(h, | |
1593 | &node_states[N_MEMORY])) | |
1594 | break; | |
1595 | } | |
1596 | h->max_huge_pages = i; | |
1597 | } | |
1598 | ||
1599 | static void __init hugetlb_init_hstates(void) | |
1600 | { | |
1601 | struct hstate *h; | |
1602 | ||
1603 | for_each_hstate(h) { | |
1604 | /* oversize hugepages were init'ed in early boot */ | |
1605 | if (!hstate_is_gigantic(h)) | |
1606 | hugetlb_hstate_alloc_pages(h); | |
1607 | } | |
1608 | } | |
1609 | ||
1610 | static char * __init memfmt(char *buf, unsigned long n) | |
1611 | { | |
1612 | if (n >= (1UL << 30)) | |
1613 | sprintf(buf, "%lu GB", n >> 30); | |
1614 | else if (n >= (1UL << 20)) | |
1615 | sprintf(buf, "%lu MB", n >> 20); | |
1616 | else | |
1617 | sprintf(buf, "%lu KB", n >> 10); | |
1618 | return buf; | |
1619 | } | |
1620 | ||
1621 | static void __init report_hugepages(void) | |
1622 | { | |
1623 | struct hstate *h; | |
1624 | ||
1625 | for_each_hstate(h) { | |
1626 | char buf[32]; | |
1627 | pr_info("HugeTLB registered %s page size, pre-allocated %ld pages\n", | |
1628 | memfmt(buf, huge_page_size(h)), | |
1629 | h->free_huge_pages); | |
1630 | } | |
1631 | } | |
1632 | ||
1633 | #ifdef CONFIG_HIGHMEM | |
1634 | static void try_to_free_low(struct hstate *h, unsigned long count, | |
1635 | nodemask_t *nodes_allowed) | |
1636 | { | |
1637 | int i; | |
1638 | ||
1639 | if (hstate_is_gigantic(h)) | |
1640 | return; | |
1641 | ||
1642 | for_each_node_mask(i, *nodes_allowed) { | |
1643 | struct page *page, *next; | |
1644 | struct list_head *freel = &h->hugepage_freelists[i]; | |
1645 | list_for_each_entry_safe(page, next, freel, lru) { | |
1646 | if (count >= h->nr_huge_pages) | |
1647 | return; | |
1648 | if (PageHighMem(page)) | |
1649 | continue; | |
1650 | list_del(&page->lru); | |
1651 | update_and_free_page(h, page); | |
1652 | h->free_huge_pages--; | |
1653 | h->free_huge_pages_node[page_to_nid(page)]--; | |
1654 | } | |
1655 | } | |
1656 | } | |
1657 | #else | |
1658 | static inline void try_to_free_low(struct hstate *h, unsigned long count, | |
1659 | nodemask_t *nodes_allowed) | |
1660 | { | |
1661 | } | |
1662 | #endif | |
1663 | ||
1664 | /* | |
1665 | * Increment or decrement surplus_huge_pages. Keep node-specific counters | |
1666 | * balanced by operating on them in a round-robin fashion. | |
1667 | * Returns 1 if an adjustment was made. | |
1668 | */ | |
1669 | static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed, | |
1670 | int delta) | |
1671 | { | |
1672 | int nr_nodes, node; | |
1673 | ||
1674 | VM_BUG_ON(delta != -1 && delta != 1); | |
1675 | ||
1676 | if (delta < 0) { | |
1677 | for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) { | |
1678 | if (h->surplus_huge_pages_node[node]) | |
1679 | goto found; | |
1680 | } | |
1681 | } else { | |
1682 | for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { | |
1683 | if (h->surplus_huge_pages_node[node] < | |
1684 | h->nr_huge_pages_node[node]) | |
1685 | goto found; | |
1686 | } | |
1687 | } | |
1688 | return 0; | |
1689 | ||
1690 | found: | |
1691 | h->surplus_huge_pages += delta; | |
1692 | h->surplus_huge_pages_node[node] += delta; | |
1693 | return 1; | |
1694 | } | |
1695 | ||
1696 | #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages) | |
1697 | static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count, | |
1698 | nodemask_t *nodes_allowed) | |
1699 | { | |
1700 | unsigned long min_count, ret; | |
1701 | ||
1702 | if (hstate_is_gigantic(h) && !gigantic_page_supported()) | |
1703 | return h->max_huge_pages; | |
1704 | ||
1705 | /* | |
1706 | * Increase the pool size | |
1707 | * First take pages out of surplus state. Then make up the | |
1708 | * remaining difference by allocating fresh huge pages. | |
1709 | * | |
1710 | * We might race with alloc_buddy_huge_page() here and be unable | |
1711 | * to convert a surplus huge page to a normal huge page. That is | |
1712 | * not critical, though, it just means the overall size of the | |
1713 | * pool might be one hugepage larger than it needs to be, but | |
1714 | * within all the constraints specified by the sysctls. | |
1715 | */ | |
1716 | spin_lock(&hugetlb_lock); | |
1717 | while (h->surplus_huge_pages && count > persistent_huge_pages(h)) { | |
1718 | if (!adjust_pool_surplus(h, nodes_allowed, -1)) | |
1719 | break; | |
1720 | } | |
1721 | ||
1722 | while (count > persistent_huge_pages(h)) { | |
1723 | /* | |
1724 | * If this allocation races such that we no longer need the | |
1725 | * page, free_huge_page will handle it by freeing the page | |
1726 | * and reducing the surplus. | |
1727 | */ | |
1728 | spin_unlock(&hugetlb_lock); | |
1729 | if (hstate_is_gigantic(h)) | |
1730 | ret = alloc_fresh_gigantic_page(h, nodes_allowed); | |
1731 | else | |
1732 | ret = alloc_fresh_huge_page(h, nodes_allowed); | |
1733 | spin_lock(&hugetlb_lock); | |
1734 | if (!ret) | |
1735 | goto out; | |
1736 | ||
1737 | /* Bail for signals. Probably ctrl-c from user */ | |
1738 | if (signal_pending(current)) | |
1739 | goto out; | |
1740 | } | |
1741 | ||
1742 | /* | |
1743 | * Decrease the pool size | |
1744 | * First return free pages to the buddy allocator (being careful | |
1745 | * to keep enough around to satisfy reservations). Then place | |
1746 | * pages into surplus state as needed so the pool will shrink | |
1747 | * to the desired size as pages become free. | |
1748 | * | |
1749 | * By placing pages into the surplus state independent of the | |
1750 | * overcommit value, we are allowing the surplus pool size to | |
1751 | * exceed overcommit. There are few sane options here. Since | |
1752 | * alloc_buddy_huge_page() is checking the global counter, | |
1753 | * though, we'll note that we're not allowed to exceed surplus | |
1754 | * and won't grow the pool anywhere else. Not until one of the | |
1755 | * sysctls are changed, or the surplus pages go out of use. | |
1756 | */ | |
1757 | min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages; | |
1758 | min_count = max(count, min_count); | |
1759 | try_to_free_low(h, min_count, nodes_allowed); | |
1760 | while (min_count < persistent_huge_pages(h)) { | |
1761 | if (!free_pool_huge_page(h, nodes_allowed, 0)) | |
1762 | break; | |
1763 | cond_resched_lock(&hugetlb_lock); | |
1764 | } | |
1765 | while (count < persistent_huge_pages(h)) { | |
1766 | if (!adjust_pool_surplus(h, nodes_allowed, 1)) | |
1767 | break; | |
1768 | } | |
1769 | out: | |
1770 | ret = persistent_huge_pages(h); | |
1771 | spin_unlock(&hugetlb_lock); | |
1772 | return ret; | |
1773 | } | |
1774 | ||
1775 | #define HSTATE_ATTR_RO(_name) \ | |
1776 | static struct kobj_attribute _name##_attr = __ATTR_RO(_name) | |
1777 | ||
1778 | #define HSTATE_ATTR(_name) \ | |
1779 | static struct kobj_attribute _name##_attr = \ | |
1780 | __ATTR(_name, 0644, _name##_show, _name##_store) | |
1781 | ||
1782 | static struct kobject *hugepages_kobj; | |
1783 | static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; | |
1784 | ||
1785 | static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp); | |
1786 | ||
1787 | static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp) | |
1788 | { | |
1789 | int i; | |
1790 | ||
1791 | for (i = 0; i < HUGE_MAX_HSTATE; i++) | |
1792 | if (hstate_kobjs[i] == kobj) { | |
1793 | if (nidp) | |
1794 | *nidp = NUMA_NO_NODE; | |
1795 | return &hstates[i]; | |
1796 | } | |
1797 | ||
1798 | return kobj_to_node_hstate(kobj, nidp); | |
1799 | } | |
1800 | ||
1801 | static ssize_t nr_hugepages_show_common(struct kobject *kobj, | |
1802 | struct kobj_attribute *attr, char *buf) | |
1803 | { | |
1804 | struct hstate *h; | |
1805 | unsigned long nr_huge_pages; | |
1806 | int nid; | |
1807 | ||
1808 | h = kobj_to_hstate(kobj, &nid); | |
1809 | if (nid == NUMA_NO_NODE) | |
1810 | nr_huge_pages = h->nr_huge_pages; | |
1811 | else | |
1812 | nr_huge_pages = h->nr_huge_pages_node[nid]; | |
1813 | ||
1814 | return sprintf(buf, "%lu\n", nr_huge_pages); | |
1815 | } | |
1816 | ||
1817 | static ssize_t __nr_hugepages_store_common(bool obey_mempolicy, | |
1818 | struct hstate *h, int nid, | |
1819 | unsigned long count, size_t len) | |
1820 | { | |
1821 | int err; | |
1822 | NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY); | |
1823 | ||
1824 | if (hstate_is_gigantic(h) && !gigantic_page_supported()) { | |
1825 | err = -EINVAL; | |
1826 | goto out; | |
1827 | } | |
1828 | ||
1829 | if (nid == NUMA_NO_NODE) { | |
1830 | /* | |
1831 | * global hstate attribute | |
1832 | */ | |
1833 | if (!(obey_mempolicy && | |
1834 | init_nodemask_of_mempolicy(nodes_allowed))) { | |
1835 | NODEMASK_FREE(nodes_allowed); | |
1836 | nodes_allowed = &node_states[N_MEMORY]; | |
1837 | } | |
1838 | } else if (nodes_allowed) { | |
1839 | /* | |
1840 | * per node hstate attribute: adjust count to global, | |
1841 | * but restrict alloc/free to the specified node. | |
1842 | */ | |
1843 | count += h->nr_huge_pages - h->nr_huge_pages_node[nid]; | |
1844 | init_nodemask_of_node(nodes_allowed, nid); | |
1845 | } else | |
1846 | nodes_allowed = &node_states[N_MEMORY]; | |
1847 | ||
1848 | h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed); | |
1849 | ||
1850 | if (nodes_allowed != &node_states[N_MEMORY]) | |
1851 | NODEMASK_FREE(nodes_allowed); | |
1852 | ||
1853 | return len; | |
1854 | out: | |
1855 | NODEMASK_FREE(nodes_allowed); | |
1856 | return err; | |
1857 | } | |
1858 | ||
1859 | static ssize_t nr_hugepages_store_common(bool obey_mempolicy, | |
1860 | struct kobject *kobj, const char *buf, | |
1861 | size_t len) | |
1862 | { | |
1863 | struct hstate *h; | |
1864 | unsigned long count; | |
1865 | int nid; | |
1866 | int err; | |
1867 | ||
1868 | err = kstrtoul(buf, 10, &count); | |
1869 | if (err) | |
1870 | return err; | |
1871 | ||
1872 | h = kobj_to_hstate(kobj, &nid); | |
1873 | return __nr_hugepages_store_common(obey_mempolicy, h, nid, count, len); | |
1874 | } | |
1875 | ||
1876 | static ssize_t nr_hugepages_show(struct kobject *kobj, | |
1877 | struct kobj_attribute *attr, char *buf) | |
1878 | { | |
1879 | return nr_hugepages_show_common(kobj, attr, buf); | |
1880 | } | |
1881 | ||
1882 | static ssize_t nr_hugepages_store(struct kobject *kobj, | |
1883 | struct kobj_attribute *attr, const char *buf, size_t len) | |
1884 | { | |
1885 | return nr_hugepages_store_common(false, kobj, buf, len); | |
1886 | } | |
1887 | HSTATE_ATTR(nr_hugepages); | |
1888 | ||
1889 | #ifdef CONFIG_NUMA | |
1890 | ||
1891 | /* | |
1892 | * hstate attribute for optionally mempolicy-based constraint on persistent | |
1893 | * huge page alloc/free. | |
1894 | */ | |
1895 | static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj, | |
1896 | struct kobj_attribute *attr, char *buf) | |
1897 | { | |
1898 | return nr_hugepages_show_common(kobj, attr, buf); | |
1899 | } | |
1900 | ||
1901 | static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj, | |
1902 | struct kobj_attribute *attr, const char *buf, size_t len) | |
1903 | { | |
1904 | return nr_hugepages_store_common(true, kobj, buf, len); | |
1905 | } | |
1906 | HSTATE_ATTR(nr_hugepages_mempolicy); | |
1907 | #endif | |
1908 | ||
1909 | ||
1910 | static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj, | |
1911 | struct kobj_attribute *attr, char *buf) | |
1912 | { | |
1913 | struct hstate *h = kobj_to_hstate(kobj, NULL); | |
1914 | return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages); | |
1915 | } | |
1916 | ||
1917 | static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj, | |
1918 | struct kobj_attribute *attr, const char *buf, size_t count) | |
1919 | { | |
1920 | int err; | |
1921 | unsigned long input; | |
1922 | struct hstate *h = kobj_to_hstate(kobj, NULL); | |
1923 | ||
1924 | if (hstate_is_gigantic(h)) | |
1925 | return -EINVAL; | |
1926 | ||
1927 | err = kstrtoul(buf, 10, &input); | |
1928 | if (err) | |
1929 | return err; | |
1930 | ||
1931 | spin_lock(&hugetlb_lock); | |
1932 | h->nr_overcommit_huge_pages = input; | |
1933 | spin_unlock(&hugetlb_lock); | |
1934 | ||
1935 | return count; | |
1936 | } | |
1937 | HSTATE_ATTR(nr_overcommit_hugepages); | |
1938 | ||
1939 | static ssize_t free_hugepages_show(struct kobject *kobj, | |
1940 | struct kobj_attribute *attr, char *buf) | |
1941 | { | |
1942 | struct hstate *h; | |
1943 | unsigned long free_huge_pages; | |
1944 | int nid; | |
1945 | ||
1946 | h = kobj_to_hstate(kobj, &nid); | |
1947 | if (nid == NUMA_NO_NODE) | |
1948 | free_huge_pages = h->free_huge_pages; | |
1949 | else | |
1950 | free_huge_pages = h->free_huge_pages_node[nid]; | |
1951 | ||
1952 | return sprintf(buf, "%lu\n", free_huge_pages); | |
1953 | } | |
1954 | HSTATE_ATTR_RO(free_hugepages); | |
1955 | ||
1956 | static ssize_t resv_hugepages_show(struct kobject *kobj, | |
1957 | struct kobj_attribute *attr, char *buf) | |
1958 | { | |
1959 | struct hstate *h = kobj_to_hstate(kobj, NULL); | |
1960 | return sprintf(buf, "%lu\n", h->resv_huge_pages); | |
1961 | } | |
1962 | HSTATE_ATTR_RO(resv_hugepages); | |
1963 | ||
1964 | static ssize_t surplus_hugepages_show(struct kobject *kobj, | |
1965 | struct kobj_attribute *attr, char *buf) | |
1966 | { | |
1967 | struct hstate *h; | |
1968 | unsigned long surplus_huge_pages; | |
1969 | int nid; | |
1970 | ||
1971 | h = kobj_to_hstate(kobj, &nid); | |
1972 | if (nid == NUMA_NO_NODE) | |
1973 | surplus_huge_pages = h->surplus_huge_pages; | |
1974 | else | |
1975 | surplus_huge_pages = h->surplus_huge_pages_node[nid]; | |
1976 | ||
1977 | return sprintf(buf, "%lu\n", surplus_huge_pages); | |
1978 | } | |
1979 | HSTATE_ATTR_RO(surplus_hugepages); | |
1980 | ||
1981 | static struct attribute *hstate_attrs[] = { | |
1982 | &nr_hugepages_attr.attr, | |
1983 | &nr_overcommit_hugepages_attr.attr, | |
1984 | &free_hugepages_attr.attr, | |
1985 | &resv_hugepages_attr.attr, | |
1986 | &surplus_hugepages_attr.attr, | |
1987 | #ifdef CONFIG_NUMA | |
1988 | &nr_hugepages_mempolicy_attr.attr, | |
1989 | #endif | |
1990 | NULL, | |
1991 | }; | |
1992 | ||
1993 | static struct attribute_group hstate_attr_group = { | |
1994 | .attrs = hstate_attrs, | |
1995 | }; | |
1996 | ||
1997 | static int hugetlb_sysfs_add_hstate(struct hstate *h, struct kobject *parent, | |
1998 | struct kobject **hstate_kobjs, | |
1999 | struct attribute_group *hstate_attr_group) | |
2000 | { | |
2001 | int retval; | |
2002 | int hi = hstate_index(h); | |
2003 | ||
2004 | hstate_kobjs[hi] = kobject_create_and_add(h->name, parent); | |
2005 | if (!hstate_kobjs[hi]) | |
2006 | return -ENOMEM; | |
2007 | ||
2008 | retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group); | |
2009 | if (retval) | |
2010 | kobject_put(hstate_kobjs[hi]); | |
2011 | ||
2012 | return retval; | |
2013 | } | |
2014 | ||
2015 | static void __init hugetlb_sysfs_init(void) | |
2016 | { | |
2017 | struct hstate *h; | |
2018 | int err; | |
2019 | ||
2020 | hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj); | |
2021 | if (!hugepages_kobj) | |
2022 | return; | |
2023 | ||
2024 | for_each_hstate(h) { | |
2025 | err = hugetlb_sysfs_add_hstate(h, hugepages_kobj, | |
2026 | hstate_kobjs, &hstate_attr_group); | |
2027 | if (err) | |
2028 | pr_err("Hugetlb: Unable to add hstate %s", h->name); | |
2029 | } | |
2030 | } | |
2031 | ||
2032 | #ifdef CONFIG_NUMA | |
2033 | ||
2034 | /* | |
2035 | * node_hstate/s - associate per node hstate attributes, via their kobjects, | |
2036 | * with node devices in node_devices[] using a parallel array. The array | |
2037 | * index of a node device or _hstate == node id. | |
2038 | * This is here to avoid any static dependency of the node device driver, in | |
2039 | * the base kernel, on the hugetlb module. | |
2040 | */ | |
2041 | struct node_hstate { | |
2042 | struct kobject *hugepages_kobj; | |
2043 | struct kobject *hstate_kobjs[HUGE_MAX_HSTATE]; | |
2044 | }; | |
2045 | struct node_hstate node_hstates[MAX_NUMNODES]; | |
2046 | ||
2047 | /* | |
2048 | * A subset of global hstate attributes for node devices | |
2049 | */ | |
2050 | static struct attribute *per_node_hstate_attrs[] = { | |
2051 | &nr_hugepages_attr.attr, | |
2052 | &free_hugepages_attr.attr, | |
2053 | &surplus_hugepages_attr.attr, | |
2054 | NULL, | |
2055 | }; | |
2056 | ||
2057 | static struct attribute_group per_node_hstate_attr_group = { | |
2058 | .attrs = per_node_hstate_attrs, | |
2059 | }; | |
2060 | ||
2061 | /* | |
2062 | * kobj_to_node_hstate - lookup global hstate for node device hstate attr kobj. | |
2063 | * Returns node id via non-NULL nidp. | |
2064 | */ | |
2065 | static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) | |
2066 | { | |
2067 | int nid; | |
2068 | ||
2069 | for (nid = 0; nid < nr_node_ids; nid++) { | |
2070 | struct node_hstate *nhs = &node_hstates[nid]; | |
2071 | int i; | |
2072 | for (i = 0; i < HUGE_MAX_HSTATE; i++) | |
2073 | if (nhs->hstate_kobjs[i] == kobj) { | |
2074 | if (nidp) | |
2075 | *nidp = nid; | |
2076 | return &hstates[i]; | |
2077 | } | |
2078 | } | |
2079 | ||
2080 | BUG(); | |
2081 | return NULL; | |
2082 | } | |
2083 | ||
2084 | /* | |
2085 | * Unregister hstate attributes from a single node device. | |
2086 | * No-op if no hstate attributes attached. | |
2087 | */ | |
2088 | static void hugetlb_unregister_node(struct node *node) | |
2089 | { | |
2090 | struct hstate *h; | |
2091 | struct node_hstate *nhs = &node_hstates[node->dev.id]; | |
2092 | ||
2093 | if (!nhs->hugepages_kobj) | |
2094 | return; /* no hstate attributes */ | |
2095 | ||
2096 | for_each_hstate(h) { | |
2097 | int idx = hstate_index(h); | |
2098 | if (nhs->hstate_kobjs[idx]) { | |
2099 | kobject_put(nhs->hstate_kobjs[idx]); | |
2100 | nhs->hstate_kobjs[idx] = NULL; | |
2101 | } | |
2102 | } | |
2103 | ||
2104 | kobject_put(nhs->hugepages_kobj); | |
2105 | nhs->hugepages_kobj = NULL; | |
2106 | } | |
2107 | ||
2108 | /* | |
2109 | * hugetlb module exit: unregister hstate attributes from node devices | |
2110 | * that have them. | |
2111 | */ | |
2112 | static void hugetlb_unregister_all_nodes(void) | |
2113 | { | |
2114 | int nid; | |
2115 | ||
2116 | /* | |
2117 | * disable node device registrations. | |
2118 | */ | |
2119 | register_hugetlbfs_with_node(NULL, NULL); | |
2120 | ||
2121 | /* | |
2122 | * remove hstate attributes from any nodes that have them. | |
2123 | */ | |
2124 | for (nid = 0; nid < nr_node_ids; nid++) | |
2125 | hugetlb_unregister_node(node_devices[nid]); | |
2126 | } | |
2127 | ||
2128 | /* | |
2129 | * Register hstate attributes for a single node device. | |
2130 | * No-op if attributes already registered. | |
2131 | */ | |
2132 | static void hugetlb_register_node(struct node *node) | |
2133 | { | |
2134 | struct hstate *h; | |
2135 | struct node_hstate *nhs = &node_hstates[node->dev.id]; | |
2136 | int err; | |
2137 | ||
2138 | if (nhs->hugepages_kobj) | |
2139 | return; /* already allocated */ | |
2140 | ||
2141 | nhs->hugepages_kobj = kobject_create_and_add("hugepages", | |
2142 | &node->dev.kobj); | |
2143 | if (!nhs->hugepages_kobj) | |
2144 | return; | |
2145 | ||
2146 | for_each_hstate(h) { | |
2147 | err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj, | |
2148 | nhs->hstate_kobjs, | |
2149 | &per_node_hstate_attr_group); | |
2150 | if (err) { | |
2151 | pr_err("Hugetlb: Unable to add hstate %s for node %d\n", | |
2152 | h->name, node->dev.id); | |
2153 | hugetlb_unregister_node(node); | |
2154 | break; | |
2155 | } | |
2156 | } | |
2157 | } | |
2158 | ||
2159 | /* | |
2160 | * hugetlb init time: register hstate attributes for all registered node | |
2161 | * devices of nodes that have memory. All on-line nodes should have | |
2162 | * registered their associated device by this time. | |
2163 | */ | |
2164 | static void __init hugetlb_register_all_nodes(void) | |
2165 | { | |
2166 | int nid; | |
2167 | ||
2168 | for_each_node_state(nid, N_MEMORY) { | |
2169 | struct node *node = node_devices[nid]; | |
2170 | if (node->dev.id == nid) | |
2171 | hugetlb_register_node(node); | |
2172 | } | |
2173 | ||
2174 | /* | |
2175 | * Let the node device driver know we're here so it can | |
2176 | * [un]register hstate attributes on node hotplug. | |
2177 | */ | |
2178 | register_hugetlbfs_with_node(hugetlb_register_node, | |
2179 | hugetlb_unregister_node); | |
2180 | } | |
2181 | #else /* !CONFIG_NUMA */ | |
2182 | ||
2183 | static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp) | |
2184 | { | |
2185 | BUG(); | |
2186 | if (nidp) | |
2187 | *nidp = -1; | |
2188 | return NULL; | |
2189 | } | |
2190 | ||
2191 | static void hugetlb_unregister_all_nodes(void) { } | |
2192 | ||
2193 | static void hugetlb_register_all_nodes(void) { } | |
2194 | ||
2195 | #endif | |
2196 | ||
2197 | static void __exit hugetlb_exit(void) | |
2198 | { | |
2199 | struct hstate *h; | |
2200 | ||
2201 | hugetlb_unregister_all_nodes(); | |
2202 | ||
2203 | for_each_hstate(h) { | |
2204 | kobject_put(hstate_kobjs[hstate_index(h)]); | |
2205 | } | |
2206 | ||
2207 | kobject_put(hugepages_kobj); | |
2208 | kfree(htlb_fault_mutex_table); | |
2209 | } | |
2210 | module_exit(hugetlb_exit); | |
2211 | ||
2212 | static int __init hugetlb_init(void) | |
2213 | { | |
2214 | int i; | |
2215 | ||
2216 | if (!hugepages_supported()) | |
2217 | return 0; | |
2218 | ||
2219 | if (!size_to_hstate(default_hstate_size)) { | |
2220 | default_hstate_size = HPAGE_SIZE; | |
2221 | if (!size_to_hstate(default_hstate_size)) | |
2222 | hugetlb_add_hstate(HUGETLB_PAGE_ORDER); | |
2223 | } | |
2224 | default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size)); | |
2225 | if (default_hstate_max_huge_pages) | |
2226 | default_hstate.max_huge_pages = default_hstate_max_huge_pages; | |
2227 | ||
2228 | hugetlb_init_hstates(); | |
2229 | gather_bootmem_prealloc(); | |
2230 | report_hugepages(); | |
2231 | ||
2232 | hugetlb_sysfs_init(); | |
2233 | hugetlb_register_all_nodes(); | |
2234 | hugetlb_cgroup_file_init(); | |
2235 | ||
2236 | #ifdef CONFIG_SMP | |
2237 | num_fault_mutexes = roundup_pow_of_two(8 * num_possible_cpus()); | |
2238 | #else | |
2239 | num_fault_mutexes = 1; | |
2240 | #endif | |
2241 | htlb_fault_mutex_table = | |
2242 | kmalloc(sizeof(struct mutex) * num_fault_mutexes, GFP_KERNEL); | |
2243 | BUG_ON(!htlb_fault_mutex_table); | |
2244 | ||
2245 | for (i = 0; i < num_fault_mutexes; i++) | |
2246 | mutex_init(&htlb_fault_mutex_table[i]); | |
2247 | return 0; | |
2248 | } | |
2249 | module_init(hugetlb_init); | |
2250 | ||
2251 | /* Should be called on processing a hugepagesz=... option */ | |
2252 | void __init hugetlb_add_hstate(unsigned order) | |
2253 | { | |
2254 | struct hstate *h; | |
2255 | unsigned long i; | |
2256 | ||
2257 | if (size_to_hstate(PAGE_SIZE << order)) { | |
2258 | pr_warning("hugepagesz= specified twice, ignoring\n"); | |
2259 | return; | |
2260 | } | |
2261 | BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE); | |
2262 | BUG_ON(order == 0); | |
2263 | h = &hstates[hugetlb_max_hstate++]; | |
2264 | h->order = order; | |
2265 | h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1); | |
2266 | h->nr_huge_pages = 0; | |
2267 | h->free_huge_pages = 0; | |
2268 | for (i = 0; i < MAX_NUMNODES; ++i) | |
2269 | INIT_LIST_HEAD(&h->hugepage_freelists[i]); | |
2270 | INIT_LIST_HEAD(&h->hugepage_activelist); | |
2271 | h->next_nid_to_alloc = first_node(node_states[N_MEMORY]); | |
2272 | h->next_nid_to_free = first_node(node_states[N_MEMORY]); | |
2273 | snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB", | |
2274 | huge_page_size(h)/1024); | |
2275 | ||
2276 | parsed_hstate = h; | |
2277 | } | |
2278 | ||
2279 | static int __init hugetlb_nrpages_setup(char *s) | |
2280 | { | |
2281 | unsigned long *mhp; | |
2282 | static unsigned long *last_mhp; | |
2283 | ||
2284 | /* | |
2285 | * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet, | |
2286 | * so this hugepages= parameter goes to the "default hstate". | |
2287 | */ | |
2288 | if (!hugetlb_max_hstate) | |
2289 | mhp = &default_hstate_max_huge_pages; | |
2290 | else | |
2291 | mhp = &parsed_hstate->max_huge_pages; | |
2292 | ||
2293 | if (mhp == last_mhp) { | |
2294 | pr_warning("hugepages= specified twice without " | |
2295 | "interleaving hugepagesz=, ignoring\n"); | |
2296 | return 1; | |
2297 | } | |
2298 | ||
2299 | if (sscanf(s, "%lu", mhp) <= 0) | |
2300 | *mhp = 0; | |
2301 | ||
2302 | /* | |
2303 | * Global state is always initialized later in hugetlb_init. | |
2304 | * But we need to allocate >= MAX_ORDER hstates here early to still | |
2305 | * use the bootmem allocator. | |
2306 | */ | |
2307 | if (hugetlb_max_hstate && parsed_hstate->order >= MAX_ORDER) | |
2308 | hugetlb_hstate_alloc_pages(parsed_hstate); | |
2309 | ||
2310 | last_mhp = mhp; | |
2311 | ||
2312 | return 1; | |
2313 | } | |
2314 | __setup("hugepages=", hugetlb_nrpages_setup); | |
2315 | ||
2316 | static int __init hugetlb_default_setup(char *s) | |
2317 | { | |
2318 | default_hstate_size = memparse(s, &s); | |
2319 | return 1; | |
2320 | } | |
2321 | __setup("default_hugepagesz=", hugetlb_default_setup); | |
2322 | ||
2323 | static unsigned int cpuset_mems_nr(unsigned int *array) | |
2324 | { | |
2325 | int node; | |
2326 | unsigned int nr = 0; | |
2327 | ||
2328 | for_each_node_mask(node, cpuset_current_mems_allowed) | |
2329 | nr += array[node]; | |
2330 | ||
2331 | return nr; | |
2332 | } | |
2333 | ||
2334 | #ifdef CONFIG_SYSCTL | |
2335 | static int hugetlb_sysctl_handler_common(bool obey_mempolicy, | |
2336 | struct ctl_table *table, int write, | |
2337 | void __user *buffer, size_t *length, loff_t *ppos) | |
2338 | { | |
2339 | struct hstate *h = &default_hstate; | |
2340 | unsigned long tmp = h->max_huge_pages; | |
2341 | int ret; | |
2342 | ||
2343 | if (!hugepages_supported()) | |
2344 | return -ENOTSUPP; | |
2345 | ||
2346 | table->data = &tmp; | |
2347 | table->maxlen = sizeof(unsigned long); | |
2348 | ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); | |
2349 | if (ret) | |
2350 | goto out; | |
2351 | ||
2352 | if (write) | |
2353 | ret = __nr_hugepages_store_common(obey_mempolicy, h, | |
2354 | NUMA_NO_NODE, tmp, *length); | |
2355 | out: | |
2356 | return ret; | |
2357 | } | |
2358 | ||
2359 | int hugetlb_sysctl_handler(struct ctl_table *table, int write, | |
2360 | void __user *buffer, size_t *length, loff_t *ppos) | |
2361 | { | |
2362 | ||
2363 | return hugetlb_sysctl_handler_common(false, table, write, | |
2364 | buffer, length, ppos); | |
2365 | } | |
2366 | ||
2367 | #ifdef CONFIG_NUMA | |
2368 | int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write, | |
2369 | void __user *buffer, size_t *length, loff_t *ppos) | |
2370 | { | |
2371 | return hugetlb_sysctl_handler_common(true, table, write, | |
2372 | buffer, length, ppos); | |
2373 | } | |
2374 | #endif /* CONFIG_NUMA */ | |
2375 | ||
2376 | int hugetlb_overcommit_handler(struct ctl_table *table, int write, | |
2377 | void __user *buffer, | |
2378 | size_t *length, loff_t *ppos) | |
2379 | { | |
2380 | struct hstate *h = &default_hstate; | |
2381 | unsigned long tmp; | |
2382 | int ret; | |
2383 | ||
2384 | if (!hugepages_supported()) | |
2385 | return -ENOTSUPP; | |
2386 | ||
2387 | tmp = h->nr_overcommit_huge_pages; | |
2388 | ||
2389 | if (write && hstate_is_gigantic(h)) | |
2390 | return -EINVAL; | |
2391 | ||
2392 | table->data = &tmp; | |
2393 | table->maxlen = sizeof(unsigned long); | |
2394 | ret = proc_doulongvec_minmax(table, write, buffer, length, ppos); | |
2395 | if (ret) | |
2396 | goto out; | |
2397 | ||
2398 | if (write) { | |
2399 | spin_lock(&hugetlb_lock); | |
2400 | h->nr_overcommit_huge_pages = tmp; | |
2401 | spin_unlock(&hugetlb_lock); | |
2402 | } | |
2403 | out: | |
2404 | return ret; | |
2405 | } | |
2406 | ||
2407 | #endif /* CONFIG_SYSCTL */ | |
2408 | ||
2409 | void hugetlb_report_meminfo(struct seq_file *m) | |
2410 | { | |
2411 | struct hstate *h = &default_hstate; | |
2412 | if (!hugepages_supported()) | |
2413 | return; | |
2414 | seq_printf(m, | |
2415 | "HugePages_Total: %5lu\n" | |
2416 | "HugePages_Free: %5lu\n" | |
2417 | "HugePages_Rsvd: %5lu\n" | |
2418 | "HugePages_Surp: %5lu\n" | |
2419 | "Hugepagesize: %8lu kB\n", | |
2420 | h->nr_huge_pages, | |
2421 | h->free_huge_pages, | |
2422 | h->resv_huge_pages, | |
2423 | h->surplus_huge_pages, | |
2424 | 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); | |
2425 | } | |
2426 | ||
2427 | int hugetlb_report_node_meminfo(int nid, char *buf) | |
2428 | { | |
2429 | struct hstate *h = &default_hstate; | |
2430 | if (!hugepages_supported()) | |
2431 | return 0; | |
2432 | return sprintf(buf, | |
2433 | "Node %d HugePages_Total: %5u\n" | |
2434 | "Node %d HugePages_Free: %5u\n" | |
2435 | "Node %d HugePages_Surp: %5u\n", | |
2436 | nid, h->nr_huge_pages_node[nid], | |
2437 | nid, h->free_huge_pages_node[nid], | |
2438 | nid, h->surplus_huge_pages_node[nid]); | |
2439 | } | |
2440 | ||
2441 | void hugetlb_show_meminfo(void) | |
2442 | { | |
2443 | struct hstate *h; | |
2444 | int nid; | |
2445 | ||
2446 | if (!hugepages_supported()) | |
2447 | return; | |
2448 | ||
2449 | for_each_node_state(nid, N_MEMORY) | |
2450 | for_each_hstate(h) | |
2451 | pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n", | |
2452 | nid, | |
2453 | h->nr_huge_pages_node[nid], | |
2454 | h->free_huge_pages_node[nid], | |
2455 | h->surplus_huge_pages_node[nid], | |
2456 | 1UL << (huge_page_order(h) + PAGE_SHIFT - 10)); | |
2457 | } | |
2458 | ||
2459 | /* Return the number pages of memory we physically have, in PAGE_SIZE units. */ | |
2460 | unsigned long hugetlb_total_pages(void) | |
2461 | { | |
2462 | struct hstate *h; | |
2463 | unsigned long nr_total_pages = 0; | |
2464 | ||
2465 | for_each_hstate(h) | |
2466 | nr_total_pages += h->nr_huge_pages * pages_per_huge_page(h); | |
2467 | return nr_total_pages; | |
2468 | } | |
2469 | ||
2470 | static int hugetlb_acct_memory(struct hstate *h, long delta) | |
2471 | { | |
2472 | int ret = -ENOMEM; | |
2473 | ||
2474 | spin_lock(&hugetlb_lock); | |
2475 | /* | |
2476 | * When cpuset is configured, it breaks the strict hugetlb page | |
2477 | * reservation as the accounting is done on a global variable. Such | |
2478 | * reservation is completely rubbish in the presence of cpuset because | |
2479 | * the reservation is not checked against page availability for the | |
2480 | * current cpuset. Application can still potentially OOM'ed by kernel | |
2481 | * with lack of free htlb page in cpuset that the task is in. | |
2482 | * Attempt to enforce strict accounting with cpuset is almost | |
2483 | * impossible (or too ugly) because cpuset is too fluid that | |
2484 | * task or memory node can be dynamically moved between cpusets. | |
2485 | * | |
2486 | * The change of semantics for shared hugetlb mapping with cpuset is | |
2487 | * undesirable. However, in order to preserve some of the semantics, | |
2488 | * we fall back to check against current free page availability as | |
2489 | * a best attempt and hopefully to minimize the impact of changing | |
2490 | * semantics that cpuset has. | |
2491 | */ | |
2492 | if (delta > 0) { | |
2493 | if (gather_surplus_pages(h, delta) < 0) | |
2494 | goto out; | |
2495 | ||
2496 | if (delta > cpuset_mems_nr(h->free_huge_pages_node)) { | |
2497 | return_unused_surplus_pages(h, delta); | |
2498 | goto out; | |
2499 | } | |
2500 | } | |
2501 | ||
2502 | ret = 0; | |
2503 | if (delta < 0) | |
2504 | return_unused_surplus_pages(h, (unsigned long) -delta); | |
2505 | ||
2506 | out: | |
2507 | spin_unlock(&hugetlb_lock); | |
2508 | return ret; | |
2509 | } | |
2510 | ||
2511 | static void hugetlb_vm_op_open(struct vm_area_struct *vma) | |
2512 | { | |
2513 | struct resv_map *resv = vma_resv_map(vma); | |
2514 | ||
2515 | /* | |
2516 | * This new VMA should share its siblings reservation map if present. | |
2517 | * The VMA will only ever have a valid reservation map pointer where | |
2518 | * it is being copied for another still existing VMA. As that VMA | |
2519 | * has a reference to the reservation map it cannot disappear until | |
2520 | * after this open call completes. It is therefore safe to take a | |
2521 | * new reference here without additional locking. | |
2522 | */ | |
2523 | if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) | |
2524 | kref_get(&resv->refs); | |
2525 | } | |
2526 | ||
2527 | static void hugetlb_vm_op_close(struct vm_area_struct *vma) | |
2528 | { | |
2529 | struct hstate *h = hstate_vma(vma); | |
2530 | struct resv_map *resv = vma_resv_map(vma); | |
2531 | struct hugepage_subpool *spool = subpool_vma(vma); | |
2532 | unsigned long reserve, start, end; | |
2533 | long gbl_reserve; | |
2534 | ||
2535 | if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER)) | |
2536 | return; | |
2537 | ||
2538 | start = vma_hugecache_offset(h, vma, vma->vm_start); | |
2539 | end = vma_hugecache_offset(h, vma, vma->vm_end); | |
2540 | ||
2541 | reserve = (end - start) - region_count(resv, start, end); | |
2542 | ||
2543 | kref_put(&resv->refs, resv_map_release); | |
2544 | ||
2545 | if (reserve) { | |
2546 | /* | |
2547 | * Decrement reserve counts. The global reserve count may be | |
2548 | * adjusted if the subpool has a minimum size. | |
2549 | */ | |
2550 | gbl_reserve = hugepage_subpool_put_pages(spool, reserve); | |
2551 | hugetlb_acct_memory(h, -gbl_reserve); | |
2552 | } | |
2553 | } | |
2554 | ||
2555 | /* | |
2556 | * We cannot handle pagefaults against hugetlb pages at all. They cause | |
2557 | * handle_mm_fault() to try to instantiate regular-sized pages in the | |
2558 | * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get | |
2559 | * this far. | |
2560 | */ | |
2561 | static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
2562 | { | |
2563 | BUG(); | |
2564 | return 0; | |
2565 | } | |
2566 | ||
2567 | const struct vm_operations_struct hugetlb_vm_ops = { | |
2568 | .fault = hugetlb_vm_op_fault, | |
2569 | .open = hugetlb_vm_op_open, | |
2570 | .close = hugetlb_vm_op_close, | |
2571 | }; | |
2572 | ||
2573 | static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, | |
2574 | int writable) | |
2575 | { | |
2576 | pte_t entry; | |
2577 | ||
2578 | if (writable) { | |
2579 | entry = huge_pte_mkwrite(huge_pte_mkdirty(mk_huge_pte(page, | |
2580 | vma->vm_page_prot))); | |
2581 | } else { | |
2582 | entry = huge_pte_wrprotect(mk_huge_pte(page, | |
2583 | vma->vm_page_prot)); | |
2584 | } | |
2585 | entry = pte_mkyoung(entry); | |
2586 | entry = pte_mkhuge(entry); | |
2587 | entry = arch_make_huge_pte(entry, vma, page, writable); | |
2588 | ||
2589 | return entry; | |
2590 | } | |
2591 | ||
2592 | static void set_huge_ptep_writable(struct vm_area_struct *vma, | |
2593 | unsigned long address, pte_t *ptep) | |
2594 | { | |
2595 | pte_t entry; | |
2596 | ||
2597 | entry = huge_pte_mkwrite(huge_pte_mkdirty(huge_ptep_get(ptep))); | |
2598 | if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) | |
2599 | update_mmu_cache(vma, address, ptep); | |
2600 | } | |
2601 | ||
2602 | static int is_hugetlb_entry_migration(pte_t pte) | |
2603 | { | |
2604 | swp_entry_t swp; | |
2605 | ||
2606 | if (huge_pte_none(pte) || pte_present(pte)) | |
2607 | return 0; | |
2608 | swp = pte_to_swp_entry(pte); | |
2609 | if (non_swap_entry(swp) && is_migration_entry(swp)) | |
2610 | return 1; | |
2611 | else | |
2612 | return 0; | |
2613 | } | |
2614 | ||
2615 | static int is_hugetlb_entry_hwpoisoned(pte_t pte) | |
2616 | { | |
2617 | swp_entry_t swp; | |
2618 | ||
2619 | if (huge_pte_none(pte) || pte_present(pte)) | |
2620 | return 0; | |
2621 | swp = pte_to_swp_entry(pte); | |
2622 | if (non_swap_entry(swp) && is_hwpoison_entry(swp)) | |
2623 | return 1; | |
2624 | else | |
2625 | return 0; | |
2626 | } | |
2627 | ||
2628 | int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, | |
2629 | struct vm_area_struct *vma) | |
2630 | { | |
2631 | pte_t *src_pte, *dst_pte, entry; | |
2632 | struct page *ptepage; | |
2633 | unsigned long addr; | |
2634 | int cow; | |
2635 | struct hstate *h = hstate_vma(vma); | |
2636 | unsigned long sz = huge_page_size(h); | |
2637 | unsigned long mmun_start; /* For mmu_notifiers */ | |
2638 | unsigned long mmun_end; /* For mmu_notifiers */ | |
2639 | int ret = 0; | |
2640 | ||
2641 | cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; | |
2642 | ||
2643 | mmun_start = vma->vm_start; | |
2644 | mmun_end = vma->vm_end; | |
2645 | if (cow) | |
2646 | mmu_notifier_invalidate_range_start(src, mmun_start, mmun_end); | |
2647 | ||
2648 | for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) { | |
2649 | spinlock_t *src_ptl, *dst_ptl; | |
2650 | src_pte = huge_pte_offset(src, addr); | |
2651 | if (!src_pte) | |
2652 | continue; | |
2653 | dst_pte = huge_pte_alloc(dst, addr, sz); | |
2654 | if (!dst_pte) { | |
2655 | ret = -ENOMEM; | |
2656 | break; | |
2657 | } | |
2658 | ||
2659 | /* If the pagetables are shared don't copy or take references */ | |
2660 | if (dst_pte == src_pte) | |
2661 | continue; | |
2662 | ||
2663 | dst_ptl = huge_pte_lock(h, dst, dst_pte); | |
2664 | src_ptl = huge_pte_lockptr(h, src, src_pte); | |
2665 | spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); | |
2666 | entry = huge_ptep_get(src_pte); | |
2667 | if (huge_pte_none(entry)) { /* skip none entry */ | |
2668 | ; | |
2669 | } else if (unlikely(is_hugetlb_entry_migration(entry) || | |
2670 | is_hugetlb_entry_hwpoisoned(entry))) { | |
2671 | swp_entry_t swp_entry = pte_to_swp_entry(entry); | |
2672 | ||
2673 | if (is_write_migration_entry(swp_entry) && cow) { | |
2674 | /* | |
2675 | * COW mappings require pages in both | |
2676 | * parent and child to be set to read. | |
2677 | */ | |
2678 | make_migration_entry_read(&swp_entry); | |
2679 | entry = swp_entry_to_pte(swp_entry); | |
2680 | set_huge_pte_at(src, addr, src_pte, entry); | |
2681 | } | |
2682 | set_huge_pte_at(dst, addr, dst_pte, entry); | |
2683 | } else { | |
2684 | if (cow) { | |
2685 | huge_ptep_set_wrprotect(src, addr, src_pte); | |
2686 | mmu_notifier_invalidate_range(src, mmun_start, | |
2687 | mmun_end); | |
2688 | } | |
2689 | entry = huge_ptep_get(src_pte); | |
2690 | ptepage = pte_page(entry); | |
2691 | get_page(ptepage); | |
2692 | page_dup_rmap(ptepage); | |
2693 | set_huge_pte_at(dst, addr, dst_pte, entry); | |
2694 | } | |
2695 | spin_unlock(src_ptl); | |
2696 | spin_unlock(dst_ptl); | |
2697 | } | |
2698 | ||
2699 | if (cow) | |
2700 | mmu_notifier_invalidate_range_end(src, mmun_start, mmun_end); | |
2701 | ||
2702 | return ret; | |
2703 | } | |
2704 | ||
2705 | void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma, | |
2706 | unsigned long start, unsigned long end, | |
2707 | struct page *ref_page) | |
2708 | { | |
2709 | int force_flush = 0; | |
2710 | struct mm_struct *mm = vma->vm_mm; | |
2711 | unsigned long address; | |
2712 | pte_t *ptep; | |
2713 | pte_t pte; | |
2714 | spinlock_t *ptl; | |
2715 | struct page *page; | |
2716 | struct hstate *h = hstate_vma(vma); | |
2717 | unsigned long sz = huge_page_size(h); | |
2718 | const unsigned long mmun_start = start; /* For mmu_notifiers */ | |
2719 | const unsigned long mmun_end = end; /* For mmu_notifiers */ | |
2720 | ||
2721 | WARN_ON(!is_vm_hugetlb_page(vma)); | |
2722 | BUG_ON(start & ~huge_page_mask(h)); | |
2723 | BUG_ON(end & ~huge_page_mask(h)); | |
2724 | ||
2725 | tlb_start_vma(tlb, vma); | |
2726 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
2727 | address = start; | |
2728 | again: | |
2729 | for (; address < end; address += sz) { | |
2730 | ptep = huge_pte_offset(mm, address); | |
2731 | if (!ptep) | |
2732 | continue; | |
2733 | ||
2734 | ptl = huge_pte_lock(h, mm, ptep); | |
2735 | if (huge_pmd_unshare(mm, &address, ptep)) | |
2736 | goto unlock; | |
2737 | ||
2738 | pte = huge_ptep_get(ptep); | |
2739 | if (huge_pte_none(pte)) | |
2740 | goto unlock; | |
2741 | ||
2742 | /* | |
2743 | * Migrating hugepage or HWPoisoned hugepage is already | |
2744 | * unmapped and its refcount is dropped, so just clear pte here. | |
2745 | */ | |
2746 | if (unlikely(!pte_present(pte))) { | |
2747 | huge_pte_clear(mm, address, ptep); | |
2748 | goto unlock; | |
2749 | } | |
2750 | ||
2751 | page = pte_page(pte); | |
2752 | /* | |
2753 | * If a reference page is supplied, it is because a specific | |
2754 | * page is being unmapped, not a range. Ensure the page we | |
2755 | * are about to unmap is the actual page of interest. | |
2756 | */ | |
2757 | if (ref_page) { | |
2758 | if (page != ref_page) | |
2759 | goto unlock; | |
2760 | ||
2761 | /* | |
2762 | * Mark the VMA as having unmapped its page so that | |
2763 | * future faults in this VMA will fail rather than | |
2764 | * looking like data was lost | |
2765 | */ | |
2766 | set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); | |
2767 | } | |
2768 | ||
2769 | pte = huge_ptep_get_and_clear(mm, address, ptep); | |
2770 | tlb_remove_tlb_entry(tlb, ptep, address); | |
2771 | if (huge_pte_dirty(pte)) | |
2772 | set_page_dirty(page); | |
2773 | ||
2774 | page_remove_rmap(page); | |
2775 | force_flush = !__tlb_remove_page(tlb, page); | |
2776 | if (force_flush) { | |
2777 | address += sz; | |
2778 | spin_unlock(ptl); | |
2779 | break; | |
2780 | } | |
2781 | /* Bail out after unmapping reference page if supplied */ | |
2782 | if (ref_page) { | |
2783 | spin_unlock(ptl); | |
2784 | break; | |
2785 | } | |
2786 | unlock: | |
2787 | spin_unlock(ptl); | |
2788 | } | |
2789 | /* | |
2790 | * mmu_gather ran out of room to batch pages, we break out of | |
2791 | * the PTE lock to avoid doing the potential expensive TLB invalidate | |
2792 | * and page-free while holding it. | |
2793 | */ | |
2794 | if (force_flush) { | |
2795 | force_flush = 0; | |
2796 | tlb_flush_mmu(tlb); | |
2797 | if (address < end && !ref_page) | |
2798 | goto again; | |
2799 | } | |
2800 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
2801 | tlb_end_vma(tlb, vma); | |
2802 | } | |
2803 | ||
2804 | void __unmap_hugepage_range_final(struct mmu_gather *tlb, | |
2805 | struct vm_area_struct *vma, unsigned long start, | |
2806 | unsigned long end, struct page *ref_page) | |
2807 | { | |
2808 | __unmap_hugepage_range(tlb, vma, start, end, ref_page); | |
2809 | ||
2810 | /* | |
2811 | * Clear this flag so that x86's huge_pmd_share page_table_shareable | |
2812 | * test will fail on a vma being torn down, and not grab a page table | |
2813 | * on its way out. We're lucky that the flag has such an appropriate | |
2814 | * name, and can in fact be safely cleared here. We could clear it | |
2815 | * before the __unmap_hugepage_range above, but all that's necessary | |
2816 | * is to clear it before releasing the i_mmap_rwsem. This works | |
2817 | * because in the context this is called, the VMA is about to be | |
2818 | * destroyed and the i_mmap_rwsem is held. | |
2819 | */ | |
2820 | vma->vm_flags &= ~VM_MAYSHARE; | |
2821 | } | |
2822 | ||
2823 | void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, | |
2824 | unsigned long end, struct page *ref_page) | |
2825 | { | |
2826 | struct mm_struct *mm; | |
2827 | struct mmu_gather tlb; | |
2828 | ||
2829 | mm = vma->vm_mm; | |
2830 | ||
2831 | tlb_gather_mmu(&tlb, mm, start, end); | |
2832 | __unmap_hugepage_range(&tlb, vma, start, end, ref_page); | |
2833 | tlb_finish_mmu(&tlb, start, end); | |
2834 | } | |
2835 | ||
2836 | /* | |
2837 | * This is called when the original mapper is failing to COW a MAP_PRIVATE | |
2838 | * mappping it owns the reserve page for. The intention is to unmap the page | |
2839 | * from other VMAs and let the children be SIGKILLed if they are faulting the | |
2840 | * same region. | |
2841 | */ | |
2842 | static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma, | |
2843 | struct page *page, unsigned long address) | |
2844 | { | |
2845 | struct hstate *h = hstate_vma(vma); | |
2846 | struct vm_area_struct *iter_vma; | |
2847 | struct address_space *mapping; | |
2848 | pgoff_t pgoff; | |
2849 | ||
2850 | /* | |
2851 | * vm_pgoff is in PAGE_SIZE units, hence the different calculation | |
2852 | * from page cache lookup which is in HPAGE_SIZE units. | |
2853 | */ | |
2854 | address = address & huge_page_mask(h); | |
2855 | pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + | |
2856 | vma->vm_pgoff; | |
2857 | mapping = file_inode(vma->vm_file)->i_mapping; | |
2858 | ||
2859 | /* | |
2860 | * Take the mapping lock for the duration of the table walk. As | |
2861 | * this mapping should be shared between all the VMAs, | |
2862 | * __unmap_hugepage_range() is called as the lock is already held | |
2863 | */ | |
2864 | i_mmap_lock_write(mapping); | |
2865 | vma_interval_tree_foreach(iter_vma, &mapping->i_mmap, pgoff, pgoff) { | |
2866 | /* Do not unmap the current VMA */ | |
2867 | if (iter_vma == vma) | |
2868 | continue; | |
2869 | ||
2870 | /* | |
2871 | * Unmap the page from other VMAs without their own reserves. | |
2872 | * They get marked to be SIGKILLed if they fault in these | |
2873 | * areas. This is because a future no-page fault on this VMA | |
2874 | * could insert a zeroed page instead of the data existing | |
2875 | * from the time of fork. This would look like data corruption | |
2876 | */ | |
2877 | if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) | |
2878 | unmap_hugepage_range(iter_vma, address, | |
2879 | address + huge_page_size(h), page); | |
2880 | } | |
2881 | i_mmap_unlock_write(mapping); | |
2882 | } | |
2883 | ||
2884 | /* | |
2885 | * Hugetlb_cow() should be called with page lock of the original hugepage held. | |
2886 | * Called with hugetlb_instantiation_mutex held and pte_page locked so we | |
2887 | * cannot race with other handlers or page migration. | |
2888 | * Keep the pte_same checks anyway to make transition from the mutex easier. | |
2889 | */ | |
2890 | static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, | |
2891 | unsigned long address, pte_t *ptep, pte_t pte, | |
2892 | struct page *pagecache_page, spinlock_t *ptl) | |
2893 | { | |
2894 | struct hstate *h = hstate_vma(vma); | |
2895 | struct page *old_page, *new_page; | |
2896 | int ret = 0, outside_reserve = 0; | |
2897 | unsigned long mmun_start; /* For mmu_notifiers */ | |
2898 | unsigned long mmun_end; /* For mmu_notifiers */ | |
2899 | ||
2900 | old_page = pte_page(pte); | |
2901 | ||
2902 | retry_avoidcopy: | |
2903 | /* If no-one else is actually using this page, avoid the copy | |
2904 | * and just make the page writable */ | |
2905 | if (page_mapcount(old_page) == 1 && PageAnon(old_page)) { | |
2906 | page_move_anon_rmap(old_page, vma, address); | |
2907 | set_huge_ptep_writable(vma, address, ptep); | |
2908 | return 0; | |
2909 | } | |
2910 | ||
2911 | /* | |
2912 | * If the process that created a MAP_PRIVATE mapping is about to | |
2913 | * perform a COW due to a shared page count, attempt to satisfy | |
2914 | * the allocation without using the existing reserves. The pagecache | |
2915 | * page is used to determine if the reserve at this address was | |
2916 | * consumed or not. If reserves were used, a partial faulted mapping | |
2917 | * at the time of fork() could consume its reserves on COW instead | |
2918 | * of the full address range. | |
2919 | */ | |
2920 | if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && | |
2921 | old_page != pagecache_page) | |
2922 | outside_reserve = 1; | |
2923 | ||
2924 | page_cache_get(old_page); | |
2925 | ||
2926 | /* | |
2927 | * Drop page table lock as buddy allocator may be called. It will | |
2928 | * be acquired again before returning to the caller, as expected. | |
2929 | */ | |
2930 | spin_unlock(ptl); | |
2931 | new_page = alloc_huge_page(vma, address, outside_reserve); | |
2932 | ||
2933 | if (IS_ERR(new_page)) { | |
2934 | /* | |
2935 | * If a process owning a MAP_PRIVATE mapping fails to COW, | |
2936 | * it is due to references held by a child and an insufficient | |
2937 | * huge page pool. To guarantee the original mappers | |
2938 | * reliability, unmap the page from child processes. The child | |
2939 | * may get SIGKILLed if it later faults. | |
2940 | */ | |
2941 | if (outside_reserve) { | |
2942 | page_cache_release(old_page); | |
2943 | BUG_ON(huge_pte_none(pte)); | |
2944 | unmap_ref_private(mm, vma, old_page, address); | |
2945 | BUG_ON(huge_pte_none(pte)); | |
2946 | spin_lock(ptl); | |
2947 | ptep = huge_pte_offset(mm, address & huge_page_mask(h)); | |
2948 | if (likely(ptep && | |
2949 | pte_same(huge_ptep_get(ptep), pte))) | |
2950 | goto retry_avoidcopy; | |
2951 | /* | |
2952 | * race occurs while re-acquiring page table | |
2953 | * lock, and our job is done. | |
2954 | */ | |
2955 | return 0; | |
2956 | } | |
2957 | ||
2958 | ret = (PTR_ERR(new_page) == -ENOMEM) ? | |
2959 | VM_FAULT_OOM : VM_FAULT_SIGBUS; | |
2960 | goto out_release_old; | |
2961 | } | |
2962 | ||
2963 | /* | |
2964 | * When the original hugepage is shared one, it does not have | |
2965 | * anon_vma prepared. | |
2966 | */ | |
2967 | if (unlikely(anon_vma_prepare(vma))) { | |
2968 | ret = VM_FAULT_OOM; | |
2969 | goto out_release_all; | |
2970 | } | |
2971 | ||
2972 | copy_user_huge_page(new_page, old_page, address, vma, | |
2973 | pages_per_huge_page(h)); | |
2974 | __SetPageUptodate(new_page); | |
2975 | ||
2976 | mmun_start = address & huge_page_mask(h); | |
2977 | mmun_end = mmun_start + huge_page_size(h); | |
2978 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); | |
2979 | ||
2980 | /* | |
2981 | * Retake the page table lock to check for racing updates | |
2982 | * before the page tables are altered | |
2983 | */ | |
2984 | spin_lock(ptl); | |
2985 | ptep = huge_pte_offset(mm, address & huge_page_mask(h)); | |
2986 | if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) { | |
2987 | ClearPagePrivate(new_page); | |
2988 | ||
2989 | /* Break COW */ | |
2990 | huge_ptep_clear_flush(vma, address, ptep); | |
2991 | mmu_notifier_invalidate_range(mm, mmun_start, mmun_end); | |
2992 | set_huge_pte_at(mm, address, ptep, | |
2993 | make_huge_pte(vma, new_page, 1)); | |
2994 | page_remove_rmap(old_page); | |
2995 | hugepage_add_new_anon_rmap(new_page, vma, address); | |
2996 | /* Make the old page be freed below */ | |
2997 | new_page = old_page; | |
2998 | } | |
2999 | spin_unlock(ptl); | |
3000 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); | |
3001 | out_release_all: | |
3002 | page_cache_release(new_page); | |
3003 | out_release_old: | |
3004 | page_cache_release(old_page); | |
3005 | ||
3006 | spin_lock(ptl); /* Caller expects lock to be held */ | |
3007 | return ret; | |
3008 | } | |
3009 | ||
3010 | /* Return the pagecache page at a given address within a VMA */ | |
3011 | static struct page *hugetlbfs_pagecache_page(struct hstate *h, | |
3012 | struct vm_area_struct *vma, unsigned long address) | |
3013 | { | |
3014 | struct address_space *mapping; | |
3015 | pgoff_t idx; | |
3016 | ||
3017 | mapping = vma->vm_file->f_mapping; | |
3018 | idx = vma_hugecache_offset(h, vma, address); | |
3019 | ||
3020 | return find_lock_page(mapping, idx); | |
3021 | } | |
3022 | ||
3023 | /* | |
3024 | * Return whether there is a pagecache page to back given address within VMA. | |
3025 | * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page. | |
3026 | */ | |
3027 | static bool hugetlbfs_pagecache_present(struct hstate *h, | |
3028 | struct vm_area_struct *vma, unsigned long address) | |
3029 | { | |
3030 | struct address_space *mapping; | |
3031 | pgoff_t idx; | |
3032 | struct page *page; | |
3033 | ||
3034 | mapping = vma->vm_file->f_mapping; | |
3035 | idx = vma_hugecache_offset(h, vma, address); | |
3036 | ||
3037 | page = find_get_page(mapping, idx); | |
3038 | if (page) | |
3039 | put_page(page); | |
3040 | return page != NULL; | |
3041 | } | |
3042 | ||
3043 | static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
3044 | struct address_space *mapping, pgoff_t idx, | |
3045 | unsigned long address, pte_t *ptep, unsigned int flags) | |
3046 | { | |
3047 | struct hstate *h = hstate_vma(vma); | |
3048 | int ret = VM_FAULT_SIGBUS; | |
3049 | int anon_rmap = 0; | |
3050 | unsigned long size; | |
3051 | struct page *page; | |
3052 | pte_t new_pte; | |
3053 | spinlock_t *ptl; | |
3054 | ||
3055 | /* | |
3056 | * Currently, we are forced to kill the process in the event the | |
3057 | * original mapper has unmapped pages from the child due to a failed | |
3058 | * COW. Warn that such a situation has occurred as it may not be obvious | |
3059 | */ | |
3060 | if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { | |
3061 | pr_warning("PID %d killed due to inadequate hugepage pool\n", | |
3062 | current->pid); | |
3063 | return ret; | |
3064 | } | |
3065 | ||
3066 | /* | |
3067 | * Use page lock to guard against racing truncation | |
3068 | * before we get page_table_lock. | |
3069 | */ | |
3070 | retry: | |
3071 | page = find_lock_page(mapping, idx); | |
3072 | if (!page) { | |
3073 | size = i_size_read(mapping->host) >> huge_page_shift(h); | |
3074 | if (idx >= size) | |
3075 | goto out; | |
3076 | page = alloc_huge_page(vma, address, 0); | |
3077 | if (IS_ERR(page)) { | |
3078 | ret = PTR_ERR(page); | |
3079 | if (ret == -ENOMEM) | |
3080 | ret = VM_FAULT_OOM; | |
3081 | else | |
3082 | ret = VM_FAULT_SIGBUS; | |
3083 | goto out; | |
3084 | } | |
3085 | clear_huge_page(page, address, pages_per_huge_page(h)); | |
3086 | __SetPageUptodate(page); | |
3087 | ||
3088 | if (vma->vm_flags & VM_MAYSHARE) { | |
3089 | int err; | |
3090 | struct inode *inode = mapping->host; | |
3091 | ||
3092 | err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); | |
3093 | if (err) { | |
3094 | put_page(page); | |
3095 | if (err == -EEXIST) | |
3096 | goto retry; | |
3097 | goto out; | |
3098 | } | |
3099 | ClearPagePrivate(page); | |
3100 | ||
3101 | spin_lock(&inode->i_lock); | |
3102 | inode->i_blocks += blocks_per_huge_page(h); | |
3103 | spin_unlock(&inode->i_lock); | |
3104 | } else { | |
3105 | lock_page(page); | |
3106 | if (unlikely(anon_vma_prepare(vma))) { | |
3107 | ret = VM_FAULT_OOM; | |
3108 | goto backout_unlocked; | |
3109 | } | |
3110 | anon_rmap = 1; | |
3111 | } | |
3112 | } else { | |
3113 | /* | |
3114 | * If memory error occurs between mmap() and fault, some process | |
3115 | * don't have hwpoisoned swap entry for errored virtual address. | |
3116 | * So we need to block hugepage fault by PG_hwpoison bit check. | |
3117 | */ | |
3118 | if (unlikely(PageHWPoison(page))) { | |
3119 | ret = VM_FAULT_HWPOISON | | |
3120 | VM_FAULT_SET_HINDEX(hstate_index(h)); | |
3121 | goto backout_unlocked; | |
3122 | } | |
3123 | } | |
3124 | ||
3125 | /* | |
3126 | * If we are going to COW a private mapping later, we examine the | |
3127 | * pending reservations for this page now. This will ensure that | |
3128 | * any allocations necessary to record that reservation occur outside | |
3129 | * the spinlock. | |
3130 | */ | |
3131 | if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) | |
3132 | if (vma_needs_reservation(h, vma, address) < 0) { | |
3133 | ret = VM_FAULT_OOM; | |
3134 | goto backout_unlocked; | |
3135 | } | |
3136 | ||
3137 | ptl = huge_pte_lockptr(h, mm, ptep); | |
3138 | spin_lock(ptl); | |
3139 | size = i_size_read(mapping->host) >> huge_page_shift(h); | |
3140 | if (idx >= size) | |
3141 | goto backout; | |
3142 | ||
3143 | ret = 0; | |
3144 | if (!huge_pte_none(huge_ptep_get(ptep))) | |
3145 | goto backout; | |
3146 | ||
3147 | if (anon_rmap) { | |
3148 | ClearPagePrivate(page); | |
3149 | hugepage_add_new_anon_rmap(page, vma, address); | |
3150 | } else | |
3151 | page_dup_rmap(page); | |
3152 | new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) | |
3153 | && (vma->vm_flags & VM_SHARED))); | |
3154 | set_huge_pte_at(mm, address, ptep, new_pte); | |
3155 | ||
3156 | if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { | |
3157 | /* Optimization, do the COW without a second fault */ | |
3158 | ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page, ptl); | |
3159 | } | |
3160 | ||
3161 | spin_unlock(ptl); | |
3162 | unlock_page(page); | |
3163 | out: | |
3164 | return ret; | |
3165 | ||
3166 | backout: | |
3167 | spin_unlock(ptl); | |
3168 | backout_unlocked: | |
3169 | unlock_page(page); | |
3170 | put_page(page); | |
3171 | goto out; | |
3172 | } | |
3173 | ||
3174 | #ifdef CONFIG_SMP | |
3175 | static u32 fault_mutex_hash(struct hstate *h, struct mm_struct *mm, | |
3176 | struct vm_area_struct *vma, | |
3177 | struct address_space *mapping, | |
3178 | pgoff_t idx, unsigned long address) | |
3179 | { | |
3180 | unsigned long key[2]; | |
3181 | u32 hash; | |
3182 | ||
3183 | if (vma->vm_flags & VM_SHARED) { | |
3184 | key[0] = (unsigned long) mapping; | |
3185 | key[1] = idx; | |
3186 | } else { | |
3187 | key[0] = (unsigned long) mm; | |
3188 | key[1] = address >> huge_page_shift(h); | |
3189 | } | |
3190 | ||
3191 | hash = jhash2((u32 *)&key, sizeof(key)/sizeof(u32), 0); | |
3192 | ||
3193 | return hash & (num_fault_mutexes - 1); | |
3194 | } | |
3195 | #else | |
3196 | /* | |
3197 | * For uniprocesor systems we always use a single mutex, so just | |
3198 | * return 0 and avoid the hashing overhead. | |
3199 | */ | |
3200 | static u32 fault_mutex_hash(struct hstate *h, struct mm_struct *mm, | |
3201 | struct vm_area_struct *vma, | |
3202 | struct address_space *mapping, | |
3203 | pgoff_t idx, unsigned long address) | |
3204 | { | |
3205 | return 0; | |
3206 | } | |
3207 | #endif | |
3208 | ||
3209 | int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, | |
3210 | unsigned long address, unsigned int flags) | |
3211 | { | |
3212 | pte_t *ptep, entry; | |
3213 | spinlock_t *ptl; | |
3214 | int ret; | |
3215 | u32 hash; | |
3216 | pgoff_t idx; | |
3217 | struct page *page = NULL; | |
3218 | struct page *pagecache_page = NULL; | |
3219 | struct hstate *h = hstate_vma(vma); | |
3220 | struct address_space *mapping; | |
3221 | int need_wait_lock = 0; | |
3222 | ||
3223 | address &= huge_page_mask(h); | |
3224 | ||
3225 | ptep = huge_pte_offset(mm, address); | |
3226 | if (ptep) { | |
3227 | entry = huge_ptep_get(ptep); | |
3228 | if (unlikely(is_hugetlb_entry_migration(entry))) { | |
3229 | migration_entry_wait_huge(vma, mm, ptep); | |
3230 | return 0; | |
3231 | } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) | |
3232 | return VM_FAULT_HWPOISON_LARGE | | |
3233 | VM_FAULT_SET_HINDEX(hstate_index(h)); | |
3234 | } | |
3235 | ||
3236 | ptep = huge_pte_alloc(mm, address, huge_page_size(h)); | |
3237 | if (!ptep) | |
3238 | return VM_FAULT_OOM; | |
3239 | ||
3240 | mapping = vma->vm_file->f_mapping; | |
3241 | idx = vma_hugecache_offset(h, vma, address); | |
3242 | ||
3243 | /* | |
3244 | * Serialize hugepage allocation and instantiation, so that we don't | |
3245 | * get spurious allocation failures if two CPUs race to instantiate | |
3246 | * the same page in the page cache. | |
3247 | */ | |
3248 | hash = fault_mutex_hash(h, mm, vma, mapping, idx, address); | |
3249 | mutex_lock(&htlb_fault_mutex_table[hash]); | |
3250 | ||
3251 | entry = huge_ptep_get(ptep); | |
3252 | if (huge_pte_none(entry)) { | |
3253 | ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags); | |
3254 | goto out_mutex; | |
3255 | } | |
3256 | ||
3257 | ret = 0; | |
3258 | ||
3259 | /* | |
3260 | * entry could be a migration/hwpoison entry at this point, so this | |
3261 | * check prevents the kernel from going below assuming that we have | |
3262 | * a active hugepage in pagecache. This goto expects the 2nd page fault, | |
3263 | * and is_hugetlb_entry_(migration|hwpoisoned) check will properly | |
3264 | * handle it. | |
3265 | */ | |
3266 | if (!pte_present(entry)) | |
3267 | goto out_mutex; | |
3268 | ||
3269 | /* | |
3270 | * If we are going to COW the mapping later, we examine the pending | |
3271 | * reservations for this page now. This will ensure that any | |
3272 | * allocations necessary to record that reservation occur outside the | |
3273 | * spinlock. For private mappings, we also lookup the pagecache | |
3274 | * page now as it is used to determine if a reservation has been | |
3275 | * consumed. | |
3276 | */ | |
3277 | if ((flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) { | |
3278 | if (vma_needs_reservation(h, vma, address) < 0) { | |
3279 | ret = VM_FAULT_OOM; | |
3280 | goto out_mutex; | |
3281 | } | |
3282 | ||
3283 | if (!(vma->vm_flags & VM_MAYSHARE)) | |
3284 | pagecache_page = hugetlbfs_pagecache_page(h, | |
3285 | vma, address); | |
3286 | } | |
3287 | ||
3288 | ptl = huge_pte_lock(h, mm, ptep); | |
3289 | ||
3290 | /* Check for a racing update before calling hugetlb_cow */ | |
3291 | if (unlikely(!pte_same(entry, huge_ptep_get(ptep)))) | |
3292 | goto out_ptl; | |
3293 | ||
3294 | /* | |
3295 | * hugetlb_cow() requires page locks of pte_page(entry) and | |
3296 | * pagecache_page, so here we need take the former one | |
3297 | * when page != pagecache_page or !pagecache_page. | |
3298 | */ | |
3299 | page = pte_page(entry); | |
3300 | if (page != pagecache_page) | |
3301 | if (!trylock_page(page)) { | |
3302 | need_wait_lock = 1; | |
3303 | goto out_ptl; | |
3304 | } | |
3305 | ||
3306 | get_page(page); | |
3307 | ||
3308 | if (flags & FAULT_FLAG_WRITE) { | |
3309 | if (!huge_pte_write(entry)) { | |
3310 | ret = hugetlb_cow(mm, vma, address, ptep, entry, | |
3311 | pagecache_page, ptl); | |
3312 | goto out_put_page; | |
3313 | } | |
3314 | entry = huge_pte_mkdirty(entry); | |
3315 | } | |
3316 | entry = pte_mkyoung(entry); | |
3317 | if (huge_ptep_set_access_flags(vma, address, ptep, entry, | |
3318 | flags & FAULT_FLAG_WRITE)) | |
3319 | update_mmu_cache(vma, address, ptep); | |
3320 | out_put_page: | |
3321 | if (page != pagecache_page) | |
3322 | unlock_page(page); | |
3323 | put_page(page); | |
3324 | out_ptl: | |
3325 | spin_unlock(ptl); | |
3326 | ||
3327 | if (pagecache_page) { | |
3328 | unlock_page(pagecache_page); | |
3329 | put_page(pagecache_page); | |
3330 | } | |
3331 | out_mutex: | |
3332 | mutex_unlock(&htlb_fault_mutex_table[hash]); | |
3333 | /* | |
3334 | * Generally it's safe to hold refcount during waiting page lock. But | |
3335 | * here we just wait to defer the next page fault to avoid busy loop and | |
3336 | * the page is not used after unlocked before returning from the current | |
3337 | * page fault. So we are safe from accessing freed page, even if we wait | |
3338 | * here without taking refcount. | |
3339 | */ | |
3340 | if (need_wait_lock) | |
3341 | wait_on_page_locked(page); | |
3342 | return ret; | |
3343 | } | |
3344 | ||
3345 | long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
3346 | struct page **pages, struct vm_area_struct **vmas, | |
3347 | unsigned long *position, unsigned long *nr_pages, | |
3348 | long i, unsigned int flags) | |
3349 | { | |
3350 | unsigned long pfn_offset; | |
3351 | unsigned long vaddr = *position; | |
3352 | unsigned long remainder = *nr_pages; | |
3353 | struct hstate *h = hstate_vma(vma); | |
3354 | ||
3355 | while (vaddr < vma->vm_end && remainder) { | |
3356 | pte_t *pte; | |
3357 | spinlock_t *ptl = NULL; | |
3358 | int absent; | |
3359 | struct page *page; | |
3360 | ||
3361 | /* | |
3362 | * If we have a pending SIGKILL, don't keep faulting pages and | |
3363 | * potentially allocating memory. | |
3364 | */ | |
3365 | if (unlikely(fatal_signal_pending(current))) { | |
3366 | remainder = 0; | |
3367 | break; | |
3368 | } | |
3369 | ||
3370 | /* | |
3371 | * Some archs (sparc64, sh*) have multiple pte_ts to | |
3372 | * each hugepage. We have to make sure we get the | |
3373 | * first, for the page indexing below to work. | |
3374 | * | |
3375 | * Note that page table lock is not held when pte is null. | |
3376 | */ | |
3377 | pte = huge_pte_offset(mm, vaddr & huge_page_mask(h)); | |
3378 | if (pte) | |
3379 | ptl = huge_pte_lock(h, mm, pte); | |
3380 | absent = !pte || huge_pte_none(huge_ptep_get(pte)); | |
3381 | ||
3382 | /* | |
3383 | * When coredumping, it suits get_dump_page if we just return | |
3384 | * an error where there's an empty slot with no huge pagecache | |
3385 | * to back it. This way, we avoid allocating a hugepage, and | |
3386 | * the sparse dumpfile avoids allocating disk blocks, but its | |
3387 | * huge holes still show up with zeroes where they need to be. | |
3388 | */ | |
3389 | if (absent && (flags & FOLL_DUMP) && | |
3390 | !hugetlbfs_pagecache_present(h, vma, vaddr)) { | |
3391 | if (pte) | |
3392 | spin_unlock(ptl); | |
3393 | remainder = 0; | |
3394 | break; | |
3395 | } | |
3396 | ||
3397 | /* | |
3398 | * We need call hugetlb_fault for both hugepages under migration | |
3399 | * (in which case hugetlb_fault waits for the migration,) and | |
3400 | * hwpoisoned hugepages (in which case we need to prevent the | |
3401 | * caller from accessing to them.) In order to do this, we use | |
3402 | * here is_swap_pte instead of is_hugetlb_entry_migration and | |
3403 | * is_hugetlb_entry_hwpoisoned. This is because it simply covers | |
3404 | * both cases, and because we can't follow correct pages | |
3405 | * directly from any kind of swap entries. | |
3406 | */ | |
3407 | if (absent || is_swap_pte(huge_ptep_get(pte)) || | |
3408 | ((flags & FOLL_WRITE) && | |
3409 | !huge_pte_write(huge_ptep_get(pte)))) { | |
3410 | int ret; | |
3411 | ||
3412 | if (pte) | |
3413 | spin_unlock(ptl); | |
3414 | ret = hugetlb_fault(mm, vma, vaddr, | |
3415 | (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); | |
3416 | if (!(ret & VM_FAULT_ERROR)) | |
3417 | continue; | |
3418 | ||
3419 | remainder = 0; | |
3420 | break; | |
3421 | } | |
3422 | ||
3423 | pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT; | |
3424 | page = pte_page(huge_ptep_get(pte)); | |
3425 | same_page: | |
3426 | if (pages) { | |
3427 | pages[i] = mem_map_offset(page, pfn_offset); | |
3428 | get_page_foll(pages[i]); | |
3429 | } | |
3430 | ||
3431 | if (vmas) | |
3432 | vmas[i] = vma; | |
3433 | ||
3434 | vaddr += PAGE_SIZE; | |
3435 | ++pfn_offset; | |
3436 | --remainder; | |
3437 | ++i; | |
3438 | if (vaddr < vma->vm_end && remainder && | |
3439 | pfn_offset < pages_per_huge_page(h)) { | |
3440 | /* | |
3441 | * We use pfn_offset to avoid touching the pageframes | |
3442 | * of this compound page. | |
3443 | */ | |
3444 | goto same_page; | |
3445 | } | |
3446 | spin_unlock(ptl); | |
3447 | } | |
3448 | *nr_pages = remainder; | |
3449 | *position = vaddr; | |
3450 | ||
3451 | return i ? i : -EFAULT; | |
3452 | } | |
3453 | ||
3454 | unsigned long hugetlb_change_protection(struct vm_area_struct *vma, | |
3455 | unsigned long address, unsigned long end, pgprot_t newprot) | |
3456 | { | |
3457 | struct mm_struct *mm = vma->vm_mm; | |
3458 | unsigned long start = address; | |
3459 | pte_t *ptep; | |
3460 | pte_t pte; | |
3461 | struct hstate *h = hstate_vma(vma); | |
3462 | unsigned long pages = 0; | |
3463 | ||
3464 | BUG_ON(address >= end); | |
3465 | flush_cache_range(vma, address, end); | |
3466 | ||
3467 | mmu_notifier_invalidate_range_start(mm, start, end); | |
3468 | i_mmap_lock_write(vma->vm_file->f_mapping); | |
3469 | for (; address < end; address += huge_page_size(h)) { | |
3470 | spinlock_t *ptl; | |
3471 | ptep = huge_pte_offset(mm, address); | |
3472 | if (!ptep) | |
3473 | continue; | |
3474 | ptl = huge_pte_lock(h, mm, ptep); | |
3475 | if (huge_pmd_unshare(mm, &address, ptep)) { | |
3476 | pages++; | |
3477 | spin_unlock(ptl); | |
3478 | continue; | |
3479 | } | |
3480 | pte = huge_ptep_get(ptep); | |
3481 | if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) { | |
3482 | spin_unlock(ptl); | |
3483 | continue; | |
3484 | } | |
3485 | if (unlikely(is_hugetlb_entry_migration(pte))) { | |
3486 | swp_entry_t entry = pte_to_swp_entry(pte); | |
3487 | ||
3488 | if (is_write_migration_entry(entry)) { | |
3489 | pte_t newpte; | |
3490 | ||
3491 | make_migration_entry_read(&entry); | |
3492 | newpte = swp_entry_to_pte(entry); | |
3493 | set_huge_pte_at(mm, address, ptep, newpte); | |
3494 | pages++; | |
3495 | } | |
3496 | spin_unlock(ptl); | |
3497 | continue; | |
3498 | } | |
3499 | if (!huge_pte_none(pte)) { | |
3500 | pte = huge_ptep_get_and_clear(mm, address, ptep); | |
3501 | pte = pte_mkhuge(huge_pte_modify(pte, newprot)); | |
3502 | pte = arch_make_huge_pte(pte, vma, NULL, 0); | |
3503 | set_huge_pte_at(mm, address, ptep, pte); | |
3504 | pages++; | |
3505 | } | |
3506 | spin_unlock(ptl); | |
3507 | } | |
3508 | /* | |
3509 | * Must flush TLB before releasing i_mmap_rwsem: x86's huge_pmd_unshare | |
3510 | * may have cleared our pud entry and done put_page on the page table: | |
3511 | * once we release i_mmap_rwsem, another task can do the final put_page | |
3512 | * and that page table be reused and filled with junk. | |
3513 | */ | |
3514 | flush_tlb_range(vma, start, end); | |
3515 | mmu_notifier_invalidate_range(mm, start, end); | |
3516 | i_mmap_unlock_write(vma->vm_file->f_mapping); | |
3517 | mmu_notifier_invalidate_range_end(mm, start, end); | |
3518 | ||
3519 | return pages << h->order; | |
3520 | } | |
3521 | ||
3522 | int hugetlb_reserve_pages(struct inode *inode, | |
3523 | long from, long to, | |
3524 | struct vm_area_struct *vma, | |
3525 | vm_flags_t vm_flags) | |
3526 | { | |
3527 | long ret, chg; | |
3528 | struct hstate *h = hstate_inode(inode); | |
3529 | struct hugepage_subpool *spool = subpool_inode(inode); | |
3530 | struct resv_map *resv_map; | |
3531 | long gbl_reserve; | |
3532 | ||
3533 | /* | |
3534 | * Only apply hugepage reservation if asked. At fault time, an | |
3535 | * attempt will be made for VM_NORESERVE to allocate a page | |
3536 | * without using reserves | |
3537 | */ | |
3538 | if (vm_flags & VM_NORESERVE) | |
3539 | return 0; | |
3540 | ||
3541 | /* | |
3542 | * Shared mappings base their reservation on the number of pages that | |
3543 | * are already allocated on behalf of the file. Private mappings need | |
3544 | * to reserve the full area even if read-only as mprotect() may be | |
3545 | * called to make the mapping read-write. Assume !vma is a shm mapping | |
3546 | */ | |
3547 | if (!vma || vma->vm_flags & VM_MAYSHARE) { | |
3548 | resv_map = inode_resv_map(inode); | |
3549 | ||
3550 | chg = region_chg(resv_map, from, to); | |
3551 | ||
3552 | } else { | |
3553 | resv_map = resv_map_alloc(); | |
3554 | if (!resv_map) | |
3555 | return -ENOMEM; | |
3556 | ||
3557 | chg = to - from; | |
3558 | ||
3559 | set_vma_resv_map(vma, resv_map); | |
3560 | set_vma_resv_flags(vma, HPAGE_RESV_OWNER); | |
3561 | } | |
3562 | ||
3563 | if (chg < 0) { | |
3564 | ret = chg; | |
3565 | goto out_err; | |
3566 | } | |
3567 | ||
3568 | /* | |
3569 | * There must be enough pages in the subpool for the mapping. If | |
3570 | * the subpool has a minimum size, there may be some global | |
3571 | * reservations already in place (gbl_reserve). | |
3572 | */ | |
3573 | gbl_reserve = hugepage_subpool_get_pages(spool, chg); | |
3574 | if (gbl_reserve < 0) { | |
3575 | ret = -ENOSPC; | |
3576 | goto out_err; | |
3577 | } | |
3578 | ||
3579 | /* | |
3580 | * Check enough hugepages are available for the reservation. | |
3581 | * Hand the pages back to the subpool if there are not | |
3582 | */ | |
3583 | ret = hugetlb_acct_memory(h, gbl_reserve); | |
3584 | if (ret < 0) { | |
3585 | /* put back original number of pages, chg */ | |
3586 | (void)hugepage_subpool_put_pages(spool, chg); | |
3587 | goto out_err; | |
3588 | } | |
3589 | ||
3590 | /* | |
3591 | * Account for the reservations made. Shared mappings record regions | |
3592 | * that have reservations as they are shared by multiple VMAs. | |
3593 | * When the last VMA disappears, the region map says how much | |
3594 | * the reservation was and the page cache tells how much of | |
3595 | * the reservation was consumed. Private mappings are per-VMA and | |
3596 | * only the consumed reservations are tracked. When the VMA | |
3597 | * disappears, the original reservation is the VMA size and the | |
3598 | * consumed reservations are stored in the map. Hence, nothing | |
3599 | * else has to be done for private mappings here | |
3600 | */ | |
3601 | if (!vma || vma->vm_flags & VM_MAYSHARE) | |
3602 | region_add(resv_map, from, to); | |
3603 | return 0; | |
3604 | out_err: | |
3605 | if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) | |
3606 | kref_put(&resv_map->refs, resv_map_release); | |
3607 | return ret; | |
3608 | } | |
3609 | ||
3610 | void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) | |
3611 | { | |
3612 | struct hstate *h = hstate_inode(inode); | |
3613 | struct resv_map *resv_map = inode_resv_map(inode); | |
3614 | long chg = 0; | |
3615 | struct hugepage_subpool *spool = subpool_inode(inode); | |
3616 | long gbl_reserve; | |
3617 | ||
3618 | if (resv_map) | |
3619 | chg = region_truncate(resv_map, offset); | |
3620 | spin_lock(&inode->i_lock); | |
3621 | inode->i_blocks -= (blocks_per_huge_page(h) * freed); | |
3622 | spin_unlock(&inode->i_lock); | |
3623 | ||
3624 | /* | |
3625 | * If the subpool has a minimum size, the number of global | |
3626 | * reservations to be released may be adjusted. | |
3627 | */ | |
3628 | gbl_reserve = hugepage_subpool_put_pages(spool, (chg - freed)); | |
3629 | hugetlb_acct_memory(h, -gbl_reserve); | |
3630 | } | |
3631 | ||
3632 | #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE | |
3633 | static unsigned long page_table_shareable(struct vm_area_struct *svma, | |
3634 | struct vm_area_struct *vma, | |
3635 | unsigned long addr, pgoff_t idx) | |
3636 | { | |
3637 | unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) + | |
3638 | svma->vm_start; | |
3639 | unsigned long sbase = saddr & PUD_MASK; | |
3640 | unsigned long s_end = sbase + PUD_SIZE; | |
3641 | ||
3642 | /* Allow segments to share if only one is marked locked */ | |
3643 | unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED; | |
3644 | unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED; | |
3645 | ||
3646 | /* | |
3647 | * match the virtual addresses, permission and the alignment of the | |
3648 | * page table page. | |
3649 | */ | |
3650 | if (pmd_index(addr) != pmd_index(saddr) || | |
3651 | vm_flags != svm_flags || | |
3652 | sbase < svma->vm_start || svma->vm_end < s_end) | |
3653 | return 0; | |
3654 | ||
3655 | return saddr; | |
3656 | } | |
3657 | ||
3658 | static int vma_shareable(struct vm_area_struct *vma, unsigned long addr) | |
3659 | { | |
3660 | unsigned long base = addr & PUD_MASK; | |
3661 | unsigned long end = base + PUD_SIZE; | |
3662 | ||
3663 | /* | |
3664 | * check on proper vm_flags and page table alignment | |
3665 | */ | |
3666 | if (vma->vm_flags & VM_MAYSHARE && | |
3667 | vma->vm_start <= base && end <= vma->vm_end) | |
3668 | return 1; | |
3669 | return 0; | |
3670 | } | |
3671 | ||
3672 | /* | |
3673 | * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc() | |
3674 | * and returns the corresponding pte. While this is not necessary for the | |
3675 | * !shared pmd case because we can allocate the pmd later as well, it makes the | |
3676 | * code much cleaner. pmd allocation is essential for the shared case because | |
3677 | * pud has to be populated inside the same i_mmap_rwsem section - otherwise | |
3678 | * racing tasks could either miss the sharing (see huge_pte_offset) or select a | |
3679 | * bad pmd for sharing. | |
3680 | */ | |
3681 | pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) | |
3682 | { | |
3683 | struct vm_area_struct *vma = find_vma(mm, addr); | |
3684 | struct address_space *mapping = vma->vm_file->f_mapping; | |
3685 | pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + | |
3686 | vma->vm_pgoff; | |
3687 | struct vm_area_struct *svma; | |
3688 | unsigned long saddr; | |
3689 | pte_t *spte = NULL; | |
3690 | pte_t *pte; | |
3691 | spinlock_t *ptl; | |
3692 | ||
3693 | if (!vma_shareable(vma, addr)) | |
3694 | return (pte_t *)pmd_alloc(mm, pud, addr); | |
3695 | ||
3696 | i_mmap_lock_write(mapping); | |
3697 | vma_interval_tree_foreach(svma, &mapping->i_mmap, idx, idx) { | |
3698 | if (svma == vma) | |
3699 | continue; | |
3700 | ||
3701 | saddr = page_table_shareable(svma, vma, addr, idx); | |
3702 | if (saddr) { | |
3703 | spte = huge_pte_offset(svma->vm_mm, saddr); | |
3704 | if (spte) { | |
3705 | mm_inc_nr_pmds(mm); | |
3706 | get_page(virt_to_page(spte)); | |
3707 | break; | |
3708 | } | |
3709 | } | |
3710 | } | |
3711 | ||
3712 | if (!spte) | |
3713 | goto out; | |
3714 | ||
3715 | ptl = huge_pte_lockptr(hstate_vma(vma), mm, spte); | |
3716 | spin_lock(ptl); | |
3717 | if (pud_none(*pud)) { | |
3718 | pud_populate(mm, pud, | |
3719 | (pmd_t *)((unsigned long)spte & PAGE_MASK)); | |
3720 | } else { | |
3721 | put_page(virt_to_page(spte)); | |
3722 | mm_inc_nr_pmds(mm); | |
3723 | } | |
3724 | spin_unlock(ptl); | |
3725 | out: | |
3726 | pte = (pte_t *)pmd_alloc(mm, pud, addr); | |
3727 | i_mmap_unlock_write(mapping); | |
3728 | return pte; | |
3729 | } | |
3730 | ||
3731 | /* | |
3732 | * unmap huge page backed by shared pte. | |
3733 | * | |
3734 | * Hugetlb pte page is ref counted at the time of mapping. If pte is shared | |
3735 | * indicated by page_count > 1, unmap is achieved by clearing pud and | |
3736 | * decrementing the ref count. If count == 1, the pte page is not shared. | |
3737 | * | |
3738 | * called with page table lock held. | |
3739 | * | |
3740 | * returns: 1 successfully unmapped a shared pte page | |
3741 | * 0 the underlying pte page is not shared, or it is the last user | |
3742 | */ | |
3743 | int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) | |
3744 | { | |
3745 | pgd_t *pgd = pgd_offset(mm, *addr); | |
3746 | pud_t *pud = pud_offset(pgd, *addr); | |
3747 | ||
3748 | BUG_ON(page_count(virt_to_page(ptep)) == 0); | |
3749 | if (page_count(virt_to_page(ptep)) == 1) | |
3750 | return 0; | |
3751 | ||
3752 | pud_clear(pud); | |
3753 | put_page(virt_to_page(ptep)); | |
3754 | mm_dec_nr_pmds(mm); | |
3755 | *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE; | |
3756 | return 1; | |
3757 | } | |
3758 | #define want_pmd_share() (1) | |
3759 | #else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ | |
3760 | pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) | |
3761 | { | |
3762 | return NULL; | |
3763 | } | |
3764 | #define want_pmd_share() (0) | |
3765 | #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ | |
3766 | ||
3767 | #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB | |
3768 | pte_t *huge_pte_alloc(struct mm_struct *mm, | |
3769 | unsigned long addr, unsigned long sz) | |
3770 | { | |
3771 | pgd_t *pgd; | |
3772 | pud_t *pud; | |
3773 | pte_t *pte = NULL; | |
3774 | ||
3775 | pgd = pgd_offset(mm, addr); | |
3776 | pud = pud_alloc(mm, pgd, addr); | |
3777 | if (pud) { | |
3778 | if (sz == PUD_SIZE) { | |
3779 | pte = (pte_t *)pud; | |
3780 | } else { | |
3781 | BUG_ON(sz != PMD_SIZE); | |
3782 | if (want_pmd_share() && pud_none(*pud)) | |
3783 | pte = huge_pmd_share(mm, addr, pud); | |
3784 | else | |
3785 | pte = (pte_t *)pmd_alloc(mm, pud, addr); | |
3786 | } | |
3787 | } | |
3788 | BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); | |
3789 | ||
3790 | return pte; | |
3791 | } | |
3792 | ||
3793 | pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) | |
3794 | { | |
3795 | pgd_t *pgd; | |
3796 | pud_t *pud; | |
3797 | pmd_t *pmd = NULL; | |
3798 | ||
3799 | pgd = pgd_offset(mm, addr); | |
3800 | if (pgd_present(*pgd)) { | |
3801 | pud = pud_offset(pgd, addr); | |
3802 | if (pud_present(*pud)) { | |
3803 | if (pud_huge(*pud)) | |
3804 | return (pte_t *)pud; | |
3805 | pmd = pmd_offset(pud, addr); | |
3806 | } | |
3807 | } | |
3808 | return (pte_t *) pmd; | |
3809 | } | |
3810 | ||
3811 | #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */ | |
3812 | ||
3813 | /* | |
3814 | * These functions are overwritable if your architecture needs its own | |
3815 | * behavior. | |
3816 | */ | |
3817 | struct page * __weak | |
3818 | follow_huge_addr(struct mm_struct *mm, unsigned long address, | |
3819 | int write) | |
3820 | { | |
3821 | return ERR_PTR(-EINVAL); | |
3822 | } | |
3823 | ||
3824 | struct page * __weak | |
3825 | follow_huge_pmd(struct mm_struct *mm, unsigned long address, | |
3826 | pmd_t *pmd, int flags) | |
3827 | { | |
3828 | struct page *page = NULL; | |
3829 | spinlock_t *ptl; | |
3830 | retry: | |
3831 | ptl = pmd_lockptr(mm, pmd); | |
3832 | spin_lock(ptl); | |
3833 | /* | |
3834 | * make sure that the address range covered by this pmd is not | |
3835 | * unmapped from other threads. | |
3836 | */ | |
3837 | if (!pmd_huge(*pmd)) | |
3838 | goto out; | |
3839 | if (pmd_present(*pmd)) { | |
3840 | page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT); | |
3841 | if (flags & FOLL_GET) | |
3842 | get_page(page); | |
3843 | } else { | |
3844 | if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) { | |
3845 | spin_unlock(ptl); | |
3846 | __migration_entry_wait(mm, (pte_t *)pmd, ptl); | |
3847 | goto retry; | |
3848 | } | |
3849 | /* | |
3850 | * hwpoisoned entry is treated as no_page_table in | |
3851 | * follow_page_mask(). | |
3852 | */ | |
3853 | } | |
3854 | out: | |
3855 | spin_unlock(ptl); | |
3856 | return page; | |
3857 | } | |
3858 | ||
3859 | struct page * __weak | |
3860 | follow_huge_pud(struct mm_struct *mm, unsigned long address, | |
3861 | pud_t *pud, int flags) | |
3862 | { | |
3863 | if (flags & FOLL_GET) | |
3864 | return NULL; | |
3865 | ||
3866 | return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT); | |
3867 | } | |
3868 | ||
3869 | #ifdef CONFIG_MEMORY_FAILURE | |
3870 | ||
3871 | /* Should be called in hugetlb_lock */ | |
3872 | static int is_hugepage_on_freelist(struct page *hpage) | |
3873 | { | |
3874 | struct page *page; | |
3875 | struct page *tmp; | |
3876 | struct hstate *h = page_hstate(hpage); | |
3877 | int nid = page_to_nid(hpage); | |
3878 | ||
3879 | list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru) | |
3880 | if (page == hpage) | |
3881 | return 1; | |
3882 | return 0; | |
3883 | } | |
3884 | ||
3885 | /* | |
3886 | * This function is called from memory failure code. | |
3887 | * Assume the caller holds page lock of the head page. | |
3888 | */ | |
3889 | int dequeue_hwpoisoned_huge_page(struct page *hpage) | |
3890 | { | |
3891 | struct hstate *h = page_hstate(hpage); | |
3892 | int nid = page_to_nid(hpage); | |
3893 | int ret = -EBUSY; | |
3894 | ||
3895 | spin_lock(&hugetlb_lock); | |
3896 | if (is_hugepage_on_freelist(hpage)) { | |
3897 | /* | |
3898 | * Hwpoisoned hugepage isn't linked to activelist or freelist, | |
3899 | * but dangling hpage->lru can trigger list-debug warnings | |
3900 | * (this happens when we call unpoison_memory() on it), | |
3901 | * so let it point to itself with list_del_init(). | |
3902 | */ | |
3903 | list_del_init(&hpage->lru); | |
3904 | set_page_refcounted(hpage); | |
3905 | h->free_huge_pages--; | |
3906 | h->free_huge_pages_node[nid]--; | |
3907 | ret = 0; | |
3908 | } | |
3909 | spin_unlock(&hugetlb_lock); | |
3910 | return ret; | |
3911 | } | |
3912 | #endif | |
3913 | ||
3914 | bool isolate_huge_page(struct page *page, struct list_head *list) | |
3915 | { | |
3916 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
3917 | if (!get_page_unless_zero(page)) | |
3918 | return false; | |
3919 | spin_lock(&hugetlb_lock); | |
3920 | list_move_tail(&page->lru, list); | |
3921 | spin_unlock(&hugetlb_lock); | |
3922 | return true; | |
3923 | } | |
3924 | ||
3925 | void putback_active_hugepage(struct page *page) | |
3926 | { | |
3927 | VM_BUG_ON_PAGE(!PageHead(page), page); | |
3928 | spin_lock(&hugetlb_lock); | |
3929 | list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist); | |
3930 | spin_unlock(&hugetlb_lock); | |
3931 | put_page(page); | |
3932 | } | |
3933 | ||
3934 | bool is_hugepage_active(struct page *page) | |
3935 | { | |
3936 | VM_BUG_ON_PAGE(!PageHuge(page), page); | |
3937 | /* | |
3938 | * This function can be called for a tail page because the caller, | |
3939 | * scan_movable_pages, scans through a given pfn-range which typically | |
3940 | * covers one memory block. In systems using gigantic hugepage (1GB | |
3941 | * for x86_64,) a hugepage is larger than a memory block, and we don't | |
3942 | * support migrating such large hugepages for now, so return false | |
3943 | * when called for tail pages. | |
3944 | */ | |
3945 | if (PageTail(page)) | |
3946 | return false; | |
3947 | /* | |
3948 | * Refcount of a hwpoisoned hugepages is 1, but they are not active, | |
3949 | * so we should return false for them. | |
3950 | */ | |
3951 | if (unlikely(PageHWPoison(page))) | |
3952 | return false; | |
3953 | return page_count(page) > 0; | |
3954 | } |