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1 | /* | |
2 | * Generic hugetlb support. | |
3 | * (C) William Irwin, April 2004 | |
4 | */ | |
5 | #include <linux/gfp.h> | |
6 | #include <linux/list.h> | |
7 | #include <linux/init.h> | |
8 | #include <linux/module.h> | |
9 | #include <linux/mm.h> | |
10 | #include <linux/sysctl.h> | |
11 | #include <linux/highmem.h> | |
12 | #include <linux/nodemask.h> | |
13 | #include <linux/pagemap.h> | |
14 | #include <linux/mempolicy.h> | |
15 | #include <linux/cpuset.h> | |
16 | #include <linux/mutex.h> | |
17 | ||
18 | #include <asm/page.h> | |
19 | #include <asm/pgtable.h> | |
20 | ||
21 | #include <linux/hugetlb.h> | |
22 | #include "internal.h" | |
23 | ||
24 | const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; | |
25 | static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages; | |
26 | static unsigned long surplus_huge_pages; | |
27 | static unsigned long nr_overcommit_huge_pages; | |
28 | unsigned long max_huge_pages; | |
29 | unsigned long sysctl_overcommit_huge_pages; | |
30 | static struct list_head hugepage_freelists[MAX_NUMNODES]; | |
31 | static unsigned int nr_huge_pages_node[MAX_NUMNODES]; | |
32 | static unsigned int free_huge_pages_node[MAX_NUMNODES]; | |
33 | static unsigned int surplus_huge_pages_node[MAX_NUMNODES]; | |
34 | static gfp_t htlb_alloc_mask = GFP_HIGHUSER; | |
35 | unsigned long hugepages_treat_as_movable; | |
36 | static int hugetlb_next_nid; | |
37 | ||
38 | /* | |
39 | * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages | |
40 | */ | |
41 | static DEFINE_SPINLOCK(hugetlb_lock); | |
42 | ||
43 | /* | |
44 | * Region tracking -- allows tracking of reservations and instantiated pages | |
45 | * across the pages in a mapping. | |
46 | */ | |
47 | struct file_region { | |
48 | struct list_head link; | |
49 | long from; | |
50 | long to; | |
51 | }; | |
52 | ||
53 | static long region_add(struct list_head *head, long f, long t) | |
54 | { | |
55 | struct file_region *rg, *nrg, *trg; | |
56 | ||
57 | /* Locate the region we are either in or before. */ | |
58 | list_for_each_entry(rg, head, link) | |
59 | if (f <= rg->to) | |
60 | break; | |
61 | ||
62 | /* Round our left edge to the current segment if it encloses us. */ | |
63 | if (f > rg->from) | |
64 | f = rg->from; | |
65 | ||
66 | /* Check for and consume any regions we now overlap with. */ | |
67 | nrg = rg; | |
68 | list_for_each_entry_safe(rg, trg, rg->link.prev, link) { | |
69 | if (&rg->link == head) | |
70 | break; | |
71 | if (rg->from > t) | |
72 | break; | |
73 | ||
74 | /* If this area reaches higher then extend our area to | |
75 | * include it completely. If this is not the first area | |
76 | * which we intend to reuse, free it. */ | |
77 | if (rg->to > t) | |
78 | t = rg->to; | |
79 | if (rg != nrg) { | |
80 | list_del(&rg->link); | |
81 | kfree(rg); | |
82 | } | |
83 | } | |
84 | nrg->from = f; | |
85 | nrg->to = t; | |
86 | return 0; | |
87 | } | |
88 | ||
89 | static long region_chg(struct list_head *head, long f, long t) | |
90 | { | |
91 | struct file_region *rg, *nrg; | |
92 | long chg = 0; | |
93 | ||
94 | /* Locate the region we are before or in. */ | |
95 | list_for_each_entry(rg, head, link) | |
96 | if (f <= rg->to) | |
97 | break; | |
98 | ||
99 | /* If we are below the current region then a new region is required. | |
100 | * Subtle, allocate a new region at the position but make it zero | |
101 | * size such that we can guarantee to record the reservation. */ | |
102 | if (&rg->link == head || t < rg->from) { | |
103 | nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); | |
104 | if (!nrg) | |
105 | return -ENOMEM; | |
106 | nrg->from = f; | |
107 | nrg->to = f; | |
108 | INIT_LIST_HEAD(&nrg->link); | |
109 | list_add(&nrg->link, rg->link.prev); | |
110 | ||
111 | return t - f; | |
112 | } | |
113 | ||
114 | /* Round our left edge to the current segment if it encloses us. */ | |
115 | if (f > rg->from) | |
116 | f = rg->from; | |
117 | chg = t - f; | |
118 | ||
119 | /* Check for and consume any regions we now overlap with. */ | |
120 | list_for_each_entry(rg, rg->link.prev, link) { | |
121 | if (&rg->link == head) | |
122 | break; | |
123 | if (rg->from > t) | |
124 | return chg; | |
125 | ||
126 | /* We overlap with this area, if it extends futher than | |
127 | * us then we must extend ourselves. Account for its | |
128 | * existing reservation. */ | |
129 | if (rg->to > t) { | |
130 | chg += rg->to - t; | |
131 | t = rg->to; | |
132 | } | |
133 | chg -= rg->to - rg->from; | |
134 | } | |
135 | return chg; | |
136 | } | |
137 | ||
138 | static long region_truncate(struct list_head *head, long end) | |
139 | { | |
140 | struct file_region *rg, *trg; | |
141 | long chg = 0; | |
142 | ||
143 | /* Locate the region we are either in or before. */ | |
144 | list_for_each_entry(rg, head, link) | |
145 | if (end <= rg->to) | |
146 | break; | |
147 | if (&rg->link == head) | |
148 | return 0; | |
149 | ||
150 | /* If we are in the middle of a region then adjust it. */ | |
151 | if (end > rg->from) { | |
152 | chg = rg->to - end; | |
153 | rg->to = end; | |
154 | rg = list_entry(rg->link.next, typeof(*rg), link); | |
155 | } | |
156 | ||
157 | /* Drop any remaining regions. */ | |
158 | list_for_each_entry_safe(rg, trg, rg->link.prev, link) { | |
159 | if (&rg->link == head) | |
160 | break; | |
161 | chg += rg->to - rg->from; | |
162 | list_del(&rg->link); | |
163 | kfree(rg); | |
164 | } | |
165 | return chg; | |
166 | } | |
167 | ||
168 | /* | |
169 | * Convert the address within this vma to the page offset within | |
170 | * the mapping, in base page units. | |
171 | */ | |
172 | static pgoff_t vma_page_offset(struct vm_area_struct *vma, | |
173 | unsigned long address) | |
174 | { | |
175 | return ((address - vma->vm_start) >> PAGE_SHIFT) + | |
176 | (vma->vm_pgoff >> PAGE_SHIFT); | |
177 | } | |
178 | ||
179 | /* | |
180 | * Convert the address within this vma to the page offset within | |
181 | * the mapping, in pagecache page units; huge pages here. | |
182 | */ | |
183 | static pgoff_t vma_pagecache_offset(struct vm_area_struct *vma, | |
184 | unsigned long address) | |
185 | { | |
186 | return ((address - vma->vm_start) >> HPAGE_SHIFT) + | |
187 | (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT)); | |
188 | } | |
189 | ||
190 | #define HPAGE_RESV_OWNER (1UL << (BITS_PER_LONG - 1)) | |
191 | #define HPAGE_RESV_UNMAPPED (1UL << (BITS_PER_LONG - 2)) | |
192 | #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED) | |
193 | /* | |
194 | * These helpers are used to track how many pages are reserved for | |
195 | * faults in a MAP_PRIVATE mapping. Only the process that called mmap() | |
196 | * is guaranteed to have their future faults succeed. | |
197 | * | |
198 | * With the exception of reset_vma_resv_huge_pages() which is called at fork(), | |
199 | * the reserve counters are updated with the hugetlb_lock held. It is safe | |
200 | * to reset the VMA at fork() time as it is not in use yet and there is no | |
201 | * chance of the global counters getting corrupted as a result of the values. | |
202 | */ | |
203 | static unsigned long get_vma_private_data(struct vm_area_struct *vma) | |
204 | { | |
205 | return (unsigned long)vma->vm_private_data; | |
206 | } | |
207 | ||
208 | static void set_vma_private_data(struct vm_area_struct *vma, | |
209 | unsigned long value) | |
210 | { | |
211 | vma->vm_private_data = (void *)value; | |
212 | } | |
213 | ||
214 | static unsigned long vma_resv_huge_pages(struct vm_area_struct *vma) | |
215 | { | |
216 | VM_BUG_ON(!is_vm_hugetlb_page(vma)); | |
217 | if (!(vma->vm_flags & VM_SHARED)) | |
218 | return get_vma_private_data(vma) & ~HPAGE_RESV_MASK; | |
219 | return 0; | |
220 | } | |
221 | ||
222 | static void set_vma_resv_huge_pages(struct vm_area_struct *vma, | |
223 | unsigned long reserve) | |
224 | { | |
225 | VM_BUG_ON(!is_vm_hugetlb_page(vma)); | |
226 | VM_BUG_ON(vma->vm_flags & VM_SHARED); | |
227 | ||
228 | set_vma_private_data(vma, | |
229 | (get_vma_private_data(vma) & HPAGE_RESV_MASK) | reserve); | |
230 | } | |
231 | ||
232 | static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags) | |
233 | { | |
234 | VM_BUG_ON(!is_vm_hugetlb_page(vma)); | |
235 | VM_BUG_ON(vma->vm_flags & VM_SHARED); | |
236 | ||
237 | set_vma_private_data(vma, get_vma_private_data(vma) | flags); | |
238 | } | |
239 | ||
240 | static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag) | |
241 | { | |
242 | VM_BUG_ON(!is_vm_hugetlb_page(vma)); | |
243 | ||
244 | return (get_vma_private_data(vma) & flag) != 0; | |
245 | } | |
246 | ||
247 | /* Decrement the reserved pages in the hugepage pool by one */ | |
248 | static void decrement_hugepage_resv_vma(struct vm_area_struct *vma) | |
249 | { | |
250 | if (vma->vm_flags & VM_NORESERVE) | |
251 | return; | |
252 | ||
253 | if (vma->vm_flags & VM_SHARED) { | |
254 | /* Shared mappings always use reserves */ | |
255 | resv_huge_pages--; | |
256 | } else { | |
257 | /* | |
258 | * Only the process that called mmap() has reserves for | |
259 | * private mappings. | |
260 | */ | |
261 | if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { | |
262 | unsigned long flags, reserve; | |
263 | resv_huge_pages--; | |
264 | flags = (unsigned long)vma->vm_private_data & | |
265 | HPAGE_RESV_MASK; | |
266 | reserve = (unsigned long)vma->vm_private_data - 1; | |
267 | vma->vm_private_data = (void *)(reserve | flags); | |
268 | } | |
269 | } | |
270 | } | |
271 | ||
272 | /* Reset counters to 0 and clear all HPAGE_RESV_* flags */ | |
273 | void reset_vma_resv_huge_pages(struct vm_area_struct *vma) | |
274 | { | |
275 | VM_BUG_ON(!is_vm_hugetlb_page(vma)); | |
276 | if (!(vma->vm_flags & VM_SHARED)) | |
277 | vma->vm_private_data = (void *)0; | |
278 | } | |
279 | ||
280 | /* Returns true if the VMA has associated reserve pages */ | |
281 | static int vma_has_private_reserves(struct vm_area_struct *vma) | |
282 | { | |
283 | if (vma->vm_flags & VM_SHARED) | |
284 | return 0; | |
285 | if (!vma_resv_huge_pages(vma)) | |
286 | return 0; | |
287 | return 1; | |
288 | } | |
289 | ||
290 | static void clear_huge_page(struct page *page, unsigned long addr) | |
291 | { | |
292 | int i; | |
293 | ||
294 | might_sleep(); | |
295 | for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) { | |
296 | cond_resched(); | |
297 | clear_user_highpage(page + i, addr + i * PAGE_SIZE); | |
298 | } | |
299 | } | |
300 | ||
301 | static void copy_huge_page(struct page *dst, struct page *src, | |
302 | unsigned long addr, struct vm_area_struct *vma) | |
303 | { | |
304 | int i; | |
305 | ||
306 | might_sleep(); | |
307 | for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) { | |
308 | cond_resched(); | |
309 | copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); | |
310 | } | |
311 | } | |
312 | ||
313 | static void enqueue_huge_page(struct page *page) | |
314 | { | |
315 | int nid = page_to_nid(page); | |
316 | list_add(&page->lru, &hugepage_freelists[nid]); | |
317 | free_huge_pages++; | |
318 | free_huge_pages_node[nid]++; | |
319 | } | |
320 | ||
321 | static struct page *dequeue_huge_page(void) | |
322 | { | |
323 | int nid; | |
324 | struct page *page = NULL; | |
325 | ||
326 | for (nid = 0; nid < MAX_NUMNODES; ++nid) { | |
327 | if (!list_empty(&hugepage_freelists[nid])) { | |
328 | page = list_entry(hugepage_freelists[nid].next, | |
329 | struct page, lru); | |
330 | list_del(&page->lru); | |
331 | free_huge_pages--; | |
332 | free_huge_pages_node[nid]--; | |
333 | break; | |
334 | } | |
335 | } | |
336 | return page; | |
337 | } | |
338 | ||
339 | static struct page *dequeue_huge_page_vma(struct vm_area_struct *vma, | |
340 | unsigned long address, int avoid_reserve) | |
341 | { | |
342 | int nid; | |
343 | struct page *page = NULL; | |
344 | struct mempolicy *mpol; | |
345 | nodemask_t *nodemask; | |
346 | struct zonelist *zonelist = huge_zonelist(vma, address, | |
347 | htlb_alloc_mask, &mpol, &nodemask); | |
348 | struct zone *zone; | |
349 | struct zoneref *z; | |
350 | ||
351 | /* | |
352 | * A child process with MAP_PRIVATE mappings created by their parent | |
353 | * have no page reserves. This check ensures that reservations are | |
354 | * not "stolen". The child may still get SIGKILLed | |
355 | */ | |
356 | if (!vma_has_private_reserves(vma) && | |
357 | free_huge_pages - resv_huge_pages == 0) | |
358 | return NULL; | |
359 | ||
360 | /* If reserves cannot be used, ensure enough pages are in the pool */ | |
361 | if (avoid_reserve && free_huge_pages - resv_huge_pages == 0) | |
362 | return NULL; | |
363 | ||
364 | for_each_zone_zonelist_nodemask(zone, z, zonelist, | |
365 | MAX_NR_ZONES - 1, nodemask) { | |
366 | nid = zone_to_nid(zone); | |
367 | if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) && | |
368 | !list_empty(&hugepage_freelists[nid])) { | |
369 | page = list_entry(hugepage_freelists[nid].next, | |
370 | struct page, lru); | |
371 | list_del(&page->lru); | |
372 | free_huge_pages--; | |
373 | free_huge_pages_node[nid]--; | |
374 | ||
375 | if (!avoid_reserve) | |
376 | decrement_hugepage_resv_vma(vma); | |
377 | ||
378 | break; | |
379 | } | |
380 | } | |
381 | mpol_cond_put(mpol); | |
382 | return page; | |
383 | } | |
384 | ||
385 | static void update_and_free_page(struct page *page) | |
386 | { | |
387 | int i; | |
388 | nr_huge_pages--; | |
389 | nr_huge_pages_node[page_to_nid(page)]--; | |
390 | for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) { | |
391 | page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | | |
392 | 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved | | |
393 | 1 << PG_private | 1<< PG_writeback); | |
394 | } | |
395 | set_compound_page_dtor(page, NULL); | |
396 | set_page_refcounted(page); | |
397 | arch_release_hugepage(page); | |
398 | __free_pages(page, HUGETLB_PAGE_ORDER); | |
399 | } | |
400 | ||
401 | static void free_huge_page(struct page *page) | |
402 | { | |
403 | int nid = page_to_nid(page); | |
404 | struct address_space *mapping; | |
405 | ||
406 | mapping = (struct address_space *) page_private(page); | |
407 | set_page_private(page, 0); | |
408 | BUG_ON(page_count(page)); | |
409 | INIT_LIST_HEAD(&page->lru); | |
410 | ||
411 | spin_lock(&hugetlb_lock); | |
412 | if (surplus_huge_pages_node[nid]) { | |
413 | update_and_free_page(page); | |
414 | surplus_huge_pages--; | |
415 | surplus_huge_pages_node[nid]--; | |
416 | } else { | |
417 | enqueue_huge_page(page); | |
418 | } | |
419 | spin_unlock(&hugetlb_lock); | |
420 | if (mapping) | |
421 | hugetlb_put_quota(mapping, 1); | |
422 | } | |
423 | ||
424 | /* | |
425 | * Increment or decrement surplus_huge_pages. Keep node-specific counters | |
426 | * balanced by operating on them in a round-robin fashion. | |
427 | * Returns 1 if an adjustment was made. | |
428 | */ | |
429 | static int adjust_pool_surplus(int delta) | |
430 | { | |
431 | static int prev_nid; | |
432 | int nid = prev_nid; | |
433 | int ret = 0; | |
434 | ||
435 | VM_BUG_ON(delta != -1 && delta != 1); | |
436 | do { | |
437 | nid = next_node(nid, node_online_map); | |
438 | if (nid == MAX_NUMNODES) | |
439 | nid = first_node(node_online_map); | |
440 | ||
441 | /* To shrink on this node, there must be a surplus page */ | |
442 | if (delta < 0 && !surplus_huge_pages_node[nid]) | |
443 | continue; | |
444 | /* Surplus cannot exceed the total number of pages */ | |
445 | if (delta > 0 && surplus_huge_pages_node[nid] >= | |
446 | nr_huge_pages_node[nid]) | |
447 | continue; | |
448 | ||
449 | surplus_huge_pages += delta; | |
450 | surplus_huge_pages_node[nid] += delta; | |
451 | ret = 1; | |
452 | break; | |
453 | } while (nid != prev_nid); | |
454 | ||
455 | prev_nid = nid; | |
456 | return ret; | |
457 | } | |
458 | ||
459 | static struct page *alloc_fresh_huge_page_node(int nid) | |
460 | { | |
461 | struct page *page; | |
462 | ||
463 | page = alloc_pages_node(nid, | |
464 | htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| | |
465 | __GFP_REPEAT|__GFP_NOWARN, | |
466 | HUGETLB_PAGE_ORDER); | |
467 | if (page) { | |
468 | if (arch_prepare_hugepage(page)) { | |
469 | __free_pages(page, HUGETLB_PAGE_ORDER); | |
470 | return NULL; | |
471 | } | |
472 | set_compound_page_dtor(page, free_huge_page); | |
473 | spin_lock(&hugetlb_lock); | |
474 | nr_huge_pages++; | |
475 | nr_huge_pages_node[nid]++; | |
476 | spin_unlock(&hugetlb_lock); | |
477 | put_page(page); /* free it into the hugepage allocator */ | |
478 | } | |
479 | ||
480 | return page; | |
481 | } | |
482 | ||
483 | static int alloc_fresh_huge_page(void) | |
484 | { | |
485 | struct page *page; | |
486 | int start_nid; | |
487 | int next_nid; | |
488 | int ret = 0; | |
489 | ||
490 | start_nid = hugetlb_next_nid; | |
491 | ||
492 | do { | |
493 | page = alloc_fresh_huge_page_node(hugetlb_next_nid); | |
494 | if (page) | |
495 | ret = 1; | |
496 | /* | |
497 | * Use a helper variable to find the next node and then | |
498 | * copy it back to hugetlb_next_nid afterwards: | |
499 | * otherwise there's a window in which a racer might | |
500 | * pass invalid nid MAX_NUMNODES to alloc_pages_node. | |
501 | * But we don't need to use a spin_lock here: it really | |
502 | * doesn't matter if occasionally a racer chooses the | |
503 | * same nid as we do. Move nid forward in the mask even | |
504 | * if we just successfully allocated a hugepage so that | |
505 | * the next caller gets hugepages on the next node. | |
506 | */ | |
507 | next_nid = next_node(hugetlb_next_nid, node_online_map); | |
508 | if (next_nid == MAX_NUMNODES) | |
509 | next_nid = first_node(node_online_map); | |
510 | hugetlb_next_nid = next_nid; | |
511 | } while (!page && hugetlb_next_nid != start_nid); | |
512 | ||
513 | if (ret) | |
514 | count_vm_event(HTLB_BUDDY_PGALLOC); | |
515 | else | |
516 | count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); | |
517 | ||
518 | return ret; | |
519 | } | |
520 | ||
521 | static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma, | |
522 | unsigned long address) | |
523 | { | |
524 | struct page *page; | |
525 | unsigned int nid; | |
526 | ||
527 | /* | |
528 | * Assume we will successfully allocate the surplus page to | |
529 | * prevent racing processes from causing the surplus to exceed | |
530 | * overcommit | |
531 | * | |
532 | * This however introduces a different race, where a process B | |
533 | * tries to grow the static hugepage pool while alloc_pages() is | |
534 | * called by process A. B will only examine the per-node | |
535 | * counters in determining if surplus huge pages can be | |
536 | * converted to normal huge pages in adjust_pool_surplus(). A | |
537 | * won't be able to increment the per-node counter, until the | |
538 | * lock is dropped by B, but B doesn't drop hugetlb_lock until | |
539 | * no more huge pages can be converted from surplus to normal | |
540 | * state (and doesn't try to convert again). Thus, we have a | |
541 | * case where a surplus huge page exists, the pool is grown, and | |
542 | * the surplus huge page still exists after, even though it | |
543 | * should just have been converted to a normal huge page. This | |
544 | * does not leak memory, though, as the hugepage will be freed | |
545 | * once it is out of use. It also does not allow the counters to | |
546 | * go out of whack in adjust_pool_surplus() as we don't modify | |
547 | * the node values until we've gotten the hugepage and only the | |
548 | * per-node value is checked there. | |
549 | */ | |
550 | spin_lock(&hugetlb_lock); | |
551 | if (surplus_huge_pages >= nr_overcommit_huge_pages) { | |
552 | spin_unlock(&hugetlb_lock); | |
553 | return NULL; | |
554 | } else { | |
555 | nr_huge_pages++; | |
556 | surplus_huge_pages++; | |
557 | } | |
558 | spin_unlock(&hugetlb_lock); | |
559 | ||
560 | page = alloc_pages(htlb_alloc_mask|__GFP_COMP| | |
561 | __GFP_REPEAT|__GFP_NOWARN, | |
562 | HUGETLB_PAGE_ORDER); | |
563 | ||
564 | spin_lock(&hugetlb_lock); | |
565 | if (page) { | |
566 | /* | |
567 | * This page is now managed by the hugetlb allocator and has | |
568 | * no users -- drop the buddy allocator's reference. | |
569 | */ | |
570 | put_page_testzero(page); | |
571 | VM_BUG_ON(page_count(page)); | |
572 | nid = page_to_nid(page); | |
573 | set_compound_page_dtor(page, free_huge_page); | |
574 | /* | |
575 | * We incremented the global counters already | |
576 | */ | |
577 | nr_huge_pages_node[nid]++; | |
578 | surplus_huge_pages_node[nid]++; | |
579 | __count_vm_event(HTLB_BUDDY_PGALLOC); | |
580 | } else { | |
581 | nr_huge_pages--; | |
582 | surplus_huge_pages--; | |
583 | __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL); | |
584 | } | |
585 | spin_unlock(&hugetlb_lock); | |
586 | ||
587 | return page; | |
588 | } | |
589 | ||
590 | /* | |
591 | * Increase the hugetlb pool such that it can accomodate a reservation | |
592 | * of size 'delta'. | |
593 | */ | |
594 | static int gather_surplus_pages(int delta) | |
595 | { | |
596 | struct list_head surplus_list; | |
597 | struct page *page, *tmp; | |
598 | int ret, i; | |
599 | int needed, allocated; | |
600 | ||
601 | needed = (resv_huge_pages + delta) - free_huge_pages; | |
602 | if (needed <= 0) { | |
603 | resv_huge_pages += delta; | |
604 | return 0; | |
605 | } | |
606 | ||
607 | allocated = 0; | |
608 | INIT_LIST_HEAD(&surplus_list); | |
609 | ||
610 | ret = -ENOMEM; | |
611 | retry: | |
612 | spin_unlock(&hugetlb_lock); | |
613 | for (i = 0; i < needed; i++) { | |
614 | page = alloc_buddy_huge_page(NULL, 0); | |
615 | if (!page) { | |
616 | /* | |
617 | * We were not able to allocate enough pages to | |
618 | * satisfy the entire reservation so we free what | |
619 | * we've allocated so far. | |
620 | */ | |
621 | spin_lock(&hugetlb_lock); | |
622 | needed = 0; | |
623 | goto free; | |
624 | } | |
625 | ||
626 | list_add(&page->lru, &surplus_list); | |
627 | } | |
628 | allocated += needed; | |
629 | ||
630 | /* | |
631 | * After retaking hugetlb_lock, we need to recalculate 'needed' | |
632 | * because either resv_huge_pages or free_huge_pages may have changed. | |
633 | */ | |
634 | spin_lock(&hugetlb_lock); | |
635 | needed = (resv_huge_pages + delta) - (free_huge_pages + allocated); | |
636 | if (needed > 0) | |
637 | goto retry; | |
638 | ||
639 | /* | |
640 | * The surplus_list now contains _at_least_ the number of extra pages | |
641 | * needed to accomodate the reservation. Add the appropriate number | |
642 | * of pages to the hugetlb pool and free the extras back to the buddy | |
643 | * allocator. Commit the entire reservation here to prevent another | |
644 | * process from stealing the pages as they are added to the pool but | |
645 | * before they are reserved. | |
646 | */ | |
647 | needed += allocated; | |
648 | resv_huge_pages += delta; | |
649 | ret = 0; | |
650 | free: | |
651 | /* Free the needed pages to the hugetlb pool */ | |
652 | list_for_each_entry_safe(page, tmp, &surplus_list, lru) { | |
653 | if ((--needed) < 0) | |
654 | break; | |
655 | list_del(&page->lru); | |
656 | enqueue_huge_page(page); | |
657 | } | |
658 | ||
659 | /* Free unnecessary surplus pages to the buddy allocator */ | |
660 | if (!list_empty(&surplus_list)) { | |
661 | spin_unlock(&hugetlb_lock); | |
662 | list_for_each_entry_safe(page, tmp, &surplus_list, lru) { | |
663 | list_del(&page->lru); | |
664 | /* | |
665 | * The page has a reference count of zero already, so | |
666 | * call free_huge_page directly instead of using | |
667 | * put_page. This must be done with hugetlb_lock | |
668 | * unlocked which is safe because free_huge_page takes | |
669 | * hugetlb_lock before deciding how to free the page. | |
670 | */ | |
671 | free_huge_page(page); | |
672 | } | |
673 | spin_lock(&hugetlb_lock); | |
674 | } | |
675 | ||
676 | return ret; | |
677 | } | |
678 | ||
679 | /* | |
680 | * When releasing a hugetlb pool reservation, any surplus pages that were | |
681 | * allocated to satisfy the reservation must be explicitly freed if they were | |
682 | * never used. | |
683 | */ | |
684 | static void return_unused_surplus_pages(unsigned long unused_resv_pages) | |
685 | { | |
686 | static int nid = -1; | |
687 | struct page *page; | |
688 | unsigned long nr_pages; | |
689 | ||
690 | /* | |
691 | * We want to release as many surplus pages as possible, spread | |
692 | * evenly across all nodes. Iterate across all nodes until we | |
693 | * can no longer free unreserved surplus pages. This occurs when | |
694 | * the nodes with surplus pages have no free pages. | |
695 | */ | |
696 | unsigned long remaining_iterations = num_online_nodes(); | |
697 | ||
698 | /* Uncommit the reservation */ | |
699 | resv_huge_pages -= unused_resv_pages; | |
700 | ||
701 | nr_pages = min(unused_resv_pages, surplus_huge_pages); | |
702 | ||
703 | while (remaining_iterations-- && nr_pages) { | |
704 | nid = next_node(nid, node_online_map); | |
705 | if (nid == MAX_NUMNODES) | |
706 | nid = first_node(node_online_map); | |
707 | ||
708 | if (!surplus_huge_pages_node[nid]) | |
709 | continue; | |
710 | ||
711 | if (!list_empty(&hugepage_freelists[nid])) { | |
712 | page = list_entry(hugepage_freelists[nid].next, | |
713 | struct page, lru); | |
714 | list_del(&page->lru); | |
715 | update_and_free_page(page); | |
716 | free_huge_pages--; | |
717 | free_huge_pages_node[nid]--; | |
718 | surplus_huge_pages--; | |
719 | surplus_huge_pages_node[nid]--; | |
720 | nr_pages--; | |
721 | remaining_iterations = num_online_nodes(); | |
722 | } | |
723 | } | |
724 | } | |
725 | ||
726 | /* | |
727 | * Determine if the huge page at addr within the vma has an associated | |
728 | * reservation. Where it does not we will need to logically increase | |
729 | * reservation and actually increase quota before an allocation can occur. | |
730 | * Where any new reservation would be required the reservation change is | |
731 | * prepared, but not committed. Once the page has been quota'd allocated | |
732 | * an instantiated the change should be committed via vma_commit_reservation. | |
733 | * No action is required on failure. | |
734 | */ | |
735 | static int vma_needs_reservation(struct vm_area_struct *vma, unsigned long addr) | |
736 | { | |
737 | struct address_space *mapping = vma->vm_file->f_mapping; | |
738 | struct inode *inode = mapping->host; | |
739 | ||
740 | if (vma->vm_flags & VM_SHARED) { | |
741 | pgoff_t idx = vma_pagecache_offset(vma, addr); | |
742 | return region_chg(&inode->i_mapping->private_list, | |
743 | idx, idx + 1); | |
744 | ||
745 | } else { | |
746 | if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) | |
747 | return 1; | |
748 | } | |
749 | ||
750 | return 0; | |
751 | } | |
752 | static void vma_commit_reservation(struct vm_area_struct *vma, | |
753 | unsigned long addr) | |
754 | { | |
755 | struct address_space *mapping = vma->vm_file->f_mapping; | |
756 | struct inode *inode = mapping->host; | |
757 | ||
758 | if (vma->vm_flags & VM_SHARED) { | |
759 | pgoff_t idx = vma_pagecache_offset(vma, addr); | |
760 | region_add(&inode->i_mapping->private_list, idx, idx + 1); | |
761 | } | |
762 | } | |
763 | ||
764 | static struct page *alloc_huge_page(struct vm_area_struct *vma, | |
765 | unsigned long addr, int avoid_reserve) | |
766 | { | |
767 | struct page *page; | |
768 | struct address_space *mapping = vma->vm_file->f_mapping; | |
769 | struct inode *inode = mapping->host; | |
770 | unsigned int chg; | |
771 | ||
772 | /* | |
773 | * Processes that did not create the mapping will have no reserves and | |
774 | * will not have accounted against quota. Check that the quota can be | |
775 | * made before satisfying the allocation | |
776 | * MAP_NORESERVE mappings may also need pages and quota allocated | |
777 | * if no reserve mapping overlaps. | |
778 | */ | |
779 | chg = vma_needs_reservation(vma, addr); | |
780 | if (chg < 0) | |
781 | return ERR_PTR(chg); | |
782 | if (chg) | |
783 | if (hugetlb_get_quota(inode->i_mapping, chg)) | |
784 | return ERR_PTR(-ENOSPC); | |
785 | ||
786 | spin_lock(&hugetlb_lock); | |
787 | page = dequeue_huge_page_vma(vma, addr, avoid_reserve); | |
788 | spin_unlock(&hugetlb_lock); | |
789 | ||
790 | if (!page) { | |
791 | page = alloc_buddy_huge_page(vma, addr); | |
792 | if (!page) { | |
793 | hugetlb_put_quota(inode->i_mapping, chg); | |
794 | return ERR_PTR(-VM_FAULT_OOM); | |
795 | } | |
796 | } | |
797 | ||
798 | set_page_refcounted(page); | |
799 | set_page_private(page, (unsigned long) mapping); | |
800 | ||
801 | vma_commit_reservation(vma, addr); | |
802 | ||
803 | return page; | |
804 | } | |
805 | ||
806 | static int __init hugetlb_init(void) | |
807 | { | |
808 | unsigned long i; | |
809 | ||
810 | if (HPAGE_SHIFT == 0) | |
811 | return 0; | |
812 | ||
813 | for (i = 0; i < MAX_NUMNODES; ++i) | |
814 | INIT_LIST_HEAD(&hugepage_freelists[i]); | |
815 | ||
816 | hugetlb_next_nid = first_node(node_online_map); | |
817 | ||
818 | for (i = 0; i < max_huge_pages; ++i) { | |
819 | if (!alloc_fresh_huge_page()) | |
820 | break; | |
821 | } | |
822 | max_huge_pages = free_huge_pages = nr_huge_pages = i; | |
823 | printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages); | |
824 | return 0; | |
825 | } | |
826 | module_init(hugetlb_init); | |
827 | ||
828 | static int __init hugetlb_setup(char *s) | |
829 | { | |
830 | if (sscanf(s, "%lu", &max_huge_pages) <= 0) | |
831 | max_huge_pages = 0; | |
832 | return 1; | |
833 | } | |
834 | __setup("hugepages=", hugetlb_setup); | |
835 | ||
836 | static unsigned int cpuset_mems_nr(unsigned int *array) | |
837 | { | |
838 | int node; | |
839 | unsigned int nr = 0; | |
840 | ||
841 | for_each_node_mask(node, cpuset_current_mems_allowed) | |
842 | nr += array[node]; | |
843 | ||
844 | return nr; | |
845 | } | |
846 | ||
847 | #ifdef CONFIG_SYSCTL | |
848 | #ifdef CONFIG_HIGHMEM | |
849 | static void try_to_free_low(unsigned long count) | |
850 | { | |
851 | int i; | |
852 | ||
853 | for (i = 0; i < MAX_NUMNODES; ++i) { | |
854 | struct page *page, *next; | |
855 | list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) { | |
856 | if (count >= nr_huge_pages) | |
857 | return; | |
858 | if (PageHighMem(page)) | |
859 | continue; | |
860 | list_del(&page->lru); | |
861 | update_and_free_page(page); | |
862 | free_huge_pages--; | |
863 | free_huge_pages_node[page_to_nid(page)]--; | |
864 | } | |
865 | } | |
866 | } | |
867 | #else | |
868 | static inline void try_to_free_low(unsigned long count) | |
869 | { | |
870 | } | |
871 | #endif | |
872 | ||
873 | #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages) | |
874 | static unsigned long set_max_huge_pages(unsigned long count) | |
875 | { | |
876 | unsigned long min_count, ret; | |
877 | ||
878 | /* | |
879 | * Increase the pool size | |
880 | * First take pages out of surplus state. Then make up the | |
881 | * remaining difference by allocating fresh huge pages. | |
882 | * | |
883 | * We might race with alloc_buddy_huge_page() here and be unable | |
884 | * to convert a surplus huge page to a normal huge page. That is | |
885 | * not critical, though, it just means the overall size of the | |
886 | * pool might be one hugepage larger than it needs to be, but | |
887 | * within all the constraints specified by the sysctls. | |
888 | */ | |
889 | spin_lock(&hugetlb_lock); | |
890 | while (surplus_huge_pages && count > persistent_huge_pages) { | |
891 | if (!adjust_pool_surplus(-1)) | |
892 | break; | |
893 | } | |
894 | ||
895 | while (count > persistent_huge_pages) { | |
896 | /* | |
897 | * If this allocation races such that we no longer need the | |
898 | * page, free_huge_page will handle it by freeing the page | |
899 | * and reducing the surplus. | |
900 | */ | |
901 | spin_unlock(&hugetlb_lock); | |
902 | ret = alloc_fresh_huge_page(); | |
903 | spin_lock(&hugetlb_lock); | |
904 | if (!ret) | |
905 | goto out; | |
906 | ||
907 | } | |
908 | ||
909 | /* | |
910 | * Decrease the pool size | |
911 | * First return free pages to the buddy allocator (being careful | |
912 | * to keep enough around to satisfy reservations). Then place | |
913 | * pages into surplus state as needed so the pool will shrink | |
914 | * to the desired size as pages become free. | |
915 | * | |
916 | * By placing pages into the surplus state independent of the | |
917 | * overcommit value, we are allowing the surplus pool size to | |
918 | * exceed overcommit. There are few sane options here. Since | |
919 | * alloc_buddy_huge_page() is checking the global counter, | |
920 | * though, we'll note that we're not allowed to exceed surplus | |
921 | * and won't grow the pool anywhere else. Not until one of the | |
922 | * sysctls are changed, or the surplus pages go out of use. | |
923 | */ | |
924 | min_count = resv_huge_pages + nr_huge_pages - free_huge_pages; | |
925 | min_count = max(count, min_count); | |
926 | try_to_free_low(min_count); | |
927 | while (min_count < persistent_huge_pages) { | |
928 | struct page *page = dequeue_huge_page(); | |
929 | if (!page) | |
930 | break; | |
931 | update_and_free_page(page); | |
932 | } | |
933 | while (count < persistent_huge_pages) { | |
934 | if (!adjust_pool_surplus(1)) | |
935 | break; | |
936 | } | |
937 | out: | |
938 | ret = persistent_huge_pages; | |
939 | spin_unlock(&hugetlb_lock); | |
940 | return ret; | |
941 | } | |
942 | ||
943 | int hugetlb_sysctl_handler(struct ctl_table *table, int write, | |
944 | struct file *file, void __user *buffer, | |
945 | size_t *length, loff_t *ppos) | |
946 | { | |
947 | proc_doulongvec_minmax(table, write, file, buffer, length, ppos); | |
948 | max_huge_pages = set_max_huge_pages(max_huge_pages); | |
949 | return 0; | |
950 | } | |
951 | ||
952 | int hugetlb_treat_movable_handler(struct ctl_table *table, int write, | |
953 | struct file *file, void __user *buffer, | |
954 | size_t *length, loff_t *ppos) | |
955 | { | |
956 | proc_dointvec(table, write, file, buffer, length, ppos); | |
957 | if (hugepages_treat_as_movable) | |
958 | htlb_alloc_mask = GFP_HIGHUSER_MOVABLE; | |
959 | else | |
960 | htlb_alloc_mask = GFP_HIGHUSER; | |
961 | return 0; | |
962 | } | |
963 | ||
964 | int hugetlb_overcommit_handler(struct ctl_table *table, int write, | |
965 | struct file *file, void __user *buffer, | |
966 | size_t *length, loff_t *ppos) | |
967 | { | |
968 | proc_doulongvec_minmax(table, write, file, buffer, length, ppos); | |
969 | spin_lock(&hugetlb_lock); | |
970 | nr_overcommit_huge_pages = sysctl_overcommit_huge_pages; | |
971 | spin_unlock(&hugetlb_lock); | |
972 | return 0; | |
973 | } | |
974 | ||
975 | #endif /* CONFIG_SYSCTL */ | |
976 | ||
977 | int hugetlb_report_meminfo(char *buf) | |
978 | { | |
979 | return sprintf(buf, | |
980 | "HugePages_Total: %5lu\n" | |
981 | "HugePages_Free: %5lu\n" | |
982 | "HugePages_Rsvd: %5lu\n" | |
983 | "HugePages_Surp: %5lu\n" | |
984 | "Hugepagesize: %5lu kB\n", | |
985 | nr_huge_pages, | |
986 | free_huge_pages, | |
987 | resv_huge_pages, | |
988 | surplus_huge_pages, | |
989 | HPAGE_SIZE/1024); | |
990 | } | |
991 | ||
992 | int hugetlb_report_node_meminfo(int nid, char *buf) | |
993 | { | |
994 | return sprintf(buf, | |
995 | "Node %d HugePages_Total: %5u\n" | |
996 | "Node %d HugePages_Free: %5u\n" | |
997 | "Node %d HugePages_Surp: %5u\n", | |
998 | nid, nr_huge_pages_node[nid], | |
999 | nid, free_huge_pages_node[nid], | |
1000 | nid, surplus_huge_pages_node[nid]); | |
1001 | } | |
1002 | ||
1003 | /* Return the number pages of memory we physically have, in PAGE_SIZE units. */ | |
1004 | unsigned long hugetlb_total_pages(void) | |
1005 | { | |
1006 | return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE); | |
1007 | } | |
1008 | ||
1009 | static int hugetlb_acct_memory(long delta) | |
1010 | { | |
1011 | int ret = -ENOMEM; | |
1012 | ||
1013 | spin_lock(&hugetlb_lock); | |
1014 | /* | |
1015 | * When cpuset is configured, it breaks the strict hugetlb page | |
1016 | * reservation as the accounting is done on a global variable. Such | |
1017 | * reservation is completely rubbish in the presence of cpuset because | |
1018 | * the reservation is not checked against page availability for the | |
1019 | * current cpuset. Application can still potentially OOM'ed by kernel | |
1020 | * with lack of free htlb page in cpuset that the task is in. | |
1021 | * Attempt to enforce strict accounting with cpuset is almost | |
1022 | * impossible (or too ugly) because cpuset is too fluid that | |
1023 | * task or memory node can be dynamically moved between cpusets. | |
1024 | * | |
1025 | * The change of semantics for shared hugetlb mapping with cpuset is | |
1026 | * undesirable. However, in order to preserve some of the semantics, | |
1027 | * we fall back to check against current free page availability as | |
1028 | * a best attempt and hopefully to minimize the impact of changing | |
1029 | * semantics that cpuset has. | |
1030 | */ | |
1031 | if (delta > 0) { | |
1032 | if (gather_surplus_pages(delta) < 0) | |
1033 | goto out; | |
1034 | ||
1035 | if (delta > cpuset_mems_nr(free_huge_pages_node)) { | |
1036 | return_unused_surplus_pages(delta); | |
1037 | goto out; | |
1038 | } | |
1039 | } | |
1040 | ||
1041 | ret = 0; | |
1042 | if (delta < 0) | |
1043 | return_unused_surplus_pages((unsigned long) -delta); | |
1044 | ||
1045 | out: | |
1046 | spin_unlock(&hugetlb_lock); | |
1047 | return ret; | |
1048 | } | |
1049 | ||
1050 | static void hugetlb_vm_op_close(struct vm_area_struct *vma) | |
1051 | { | |
1052 | unsigned long reserve = vma_resv_huge_pages(vma); | |
1053 | if (reserve) | |
1054 | hugetlb_acct_memory(-reserve); | |
1055 | } | |
1056 | ||
1057 | /* | |
1058 | * We cannot handle pagefaults against hugetlb pages at all. They cause | |
1059 | * handle_mm_fault() to try to instantiate regular-sized pages in the | |
1060 | * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get | |
1061 | * this far. | |
1062 | */ | |
1063 | static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
1064 | { | |
1065 | BUG(); | |
1066 | return 0; | |
1067 | } | |
1068 | ||
1069 | struct vm_operations_struct hugetlb_vm_ops = { | |
1070 | .fault = hugetlb_vm_op_fault, | |
1071 | .close = hugetlb_vm_op_close, | |
1072 | }; | |
1073 | ||
1074 | static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, | |
1075 | int writable) | |
1076 | { | |
1077 | pte_t entry; | |
1078 | ||
1079 | if (writable) { | |
1080 | entry = | |
1081 | pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot))); | |
1082 | } else { | |
1083 | entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot)); | |
1084 | } | |
1085 | entry = pte_mkyoung(entry); | |
1086 | entry = pte_mkhuge(entry); | |
1087 | ||
1088 | return entry; | |
1089 | } | |
1090 | ||
1091 | static void set_huge_ptep_writable(struct vm_area_struct *vma, | |
1092 | unsigned long address, pte_t *ptep) | |
1093 | { | |
1094 | pte_t entry; | |
1095 | ||
1096 | entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep))); | |
1097 | if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) { | |
1098 | update_mmu_cache(vma, address, entry); | |
1099 | } | |
1100 | } | |
1101 | ||
1102 | ||
1103 | int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, | |
1104 | struct vm_area_struct *vma) | |
1105 | { | |
1106 | pte_t *src_pte, *dst_pte, entry; | |
1107 | struct page *ptepage; | |
1108 | unsigned long addr; | |
1109 | int cow; | |
1110 | ||
1111 | cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; | |
1112 | ||
1113 | for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) { | |
1114 | src_pte = huge_pte_offset(src, addr); | |
1115 | if (!src_pte) | |
1116 | continue; | |
1117 | dst_pte = huge_pte_alloc(dst, addr); | |
1118 | if (!dst_pte) | |
1119 | goto nomem; | |
1120 | ||
1121 | /* If the pagetables are shared don't copy or take references */ | |
1122 | if (dst_pte == src_pte) | |
1123 | continue; | |
1124 | ||
1125 | spin_lock(&dst->page_table_lock); | |
1126 | spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING); | |
1127 | if (!huge_pte_none(huge_ptep_get(src_pte))) { | |
1128 | if (cow) | |
1129 | huge_ptep_set_wrprotect(src, addr, src_pte); | |
1130 | entry = huge_ptep_get(src_pte); | |
1131 | ptepage = pte_page(entry); | |
1132 | get_page(ptepage); | |
1133 | set_huge_pte_at(dst, addr, dst_pte, entry); | |
1134 | } | |
1135 | spin_unlock(&src->page_table_lock); | |
1136 | spin_unlock(&dst->page_table_lock); | |
1137 | } | |
1138 | return 0; | |
1139 | ||
1140 | nomem: | |
1141 | return -ENOMEM; | |
1142 | } | |
1143 | ||
1144 | void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, | |
1145 | unsigned long end, struct page *ref_page) | |
1146 | { | |
1147 | struct mm_struct *mm = vma->vm_mm; | |
1148 | unsigned long address; | |
1149 | pte_t *ptep; | |
1150 | pte_t pte; | |
1151 | struct page *page; | |
1152 | struct page *tmp; | |
1153 | /* | |
1154 | * A page gathering list, protected by per file i_mmap_lock. The | |
1155 | * lock is used to avoid list corruption from multiple unmapping | |
1156 | * of the same page since we are using page->lru. | |
1157 | */ | |
1158 | LIST_HEAD(page_list); | |
1159 | ||
1160 | WARN_ON(!is_vm_hugetlb_page(vma)); | |
1161 | BUG_ON(start & ~HPAGE_MASK); | |
1162 | BUG_ON(end & ~HPAGE_MASK); | |
1163 | ||
1164 | spin_lock(&mm->page_table_lock); | |
1165 | for (address = start; address < end; address += HPAGE_SIZE) { | |
1166 | ptep = huge_pte_offset(mm, address); | |
1167 | if (!ptep) | |
1168 | continue; | |
1169 | ||
1170 | if (huge_pmd_unshare(mm, &address, ptep)) | |
1171 | continue; | |
1172 | ||
1173 | /* | |
1174 | * If a reference page is supplied, it is because a specific | |
1175 | * page is being unmapped, not a range. Ensure the page we | |
1176 | * are about to unmap is the actual page of interest. | |
1177 | */ | |
1178 | if (ref_page) { | |
1179 | pte = huge_ptep_get(ptep); | |
1180 | if (huge_pte_none(pte)) | |
1181 | continue; | |
1182 | page = pte_page(pte); | |
1183 | if (page != ref_page) | |
1184 | continue; | |
1185 | ||
1186 | /* | |
1187 | * Mark the VMA as having unmapped its page so that | |
1188 | * future faults in this VMA will fail rather than | |
1189 | * looking like data was lost | |
1190 | */ | |
1191 | set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED); | |
1192 | } | |
1193 | ||
1194 | pte = huge_ptep_get_and_clear(mm, address, ptep); | |
1195 | if (huge_pte_none(pte)) | |
1196 | continue; | |
1197 | ||
1198 | page = pte_page(pte); | |
1199 | if (pte_dirty(pte)) | |
1200 | set_page_dirty(page); | |
1201 | list_add(&page->lru, &page_list); | |
1202 | } | |
1203 | spin_unlock(&mm->page_table_lock); | |
1204 | flush_tlb_range(vma, start, end); | |
1205 | list_for_each_entry_safe(page, tmp, &page_list, lru) { | |
1206 | list_del(&page->lru); | |
1207 | put_page(page); | |
1208 | } | |
1209 | } | |
1210 | ||
1211 | void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, | |
1212 | unsigned long end, struct page *ref_page) | |
1213 | { | |
1214 | /* | |
1215 | * It is undesirable to test vma->vm_file as it should be non-null | |
1216 | * for valid hugetlb area. However, vm_file will be NULL in the error | |
1217 | * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails, | |
1218 | * do_mmap_pgoff() nullifies vma->vm_file before calling this function | |
1219 | * to clean up. Since no pte has actually been setup, it is safe to | |
1220 | * do nothing in this case. | |
1221 | */ | |
1222 | if (vma->vm_file) { | |
1223 | spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); | |
1224 | __unmap_hugepage_range(vma, start, end, ref_page); | |
1225 | spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); | |
1226 | } | |
1227 | } | |
1228 | ||
1229 | /* | |
1230 | * This is called when the original mapper is failing to COW a MAP_PRIVATE | |
1231 | * mappping it owns the reserve page for. The intention is to unmap the page | |
1232 | * from other VMAs and let the children be SIGKILLed if they are faulting the | |
1233 | * same region. | |
1234 | */ | |
1235 | int unmap_ref_private(struct mm_struct *mm, | |
1236 | struct vm_area_struct *vma, | |
1237 | struct page *page, | |
1238 | unsigned long address) | |
1239 | { | |
1240 | struct vm_area_struct *iter_vma; | |
1241 | struct address_space *mapping; | |
1242 | struct prio_tree_iter iter; | |
1243 | pgoff_t pgoff; | |
1244 | ||
1245 | /* | |
1246 | * vm_pgoff is in PAGE_SIZE units, hence the different calculation | |
1247 | * from page cache lookup which is in HPAGE_SIZE units. | |
1248 | */ | |
1249 | address = address & huge_page_mask(hstate_vma(vma)); | |
1250 | pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) | |
1251 | + (vma->vm_pgoff >> PAGE_SHIFT); | |
1252 | mapping = (struct address_space *)page_private(page); | |
1253 | ||
1254 | vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
1255 | /* Do not unmap the current VMA */ | |
1256 | if (iter_vma == vma) | |
1257 | continue; | |
1258 | ||
1259 | /* | |
1260 | * Unmap the page from other VMAs without their own reserves. | |
1261 | * They get marked to be SIGKILLed if they fault in these | |
1262 | * areas. This is because a future no-page fault on this VMA | |
1263 | * could insert a zeroed page instead of the data existing | |
1264 | * from the time of fork. This would look like data corruption | |
1265 | */ | |
1266 | if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER)) | |
1267 | unmap_hugepage_range(iter_vma, | |
1268 | address, address + HPAGE_SIZE, | |
1269 | page); | |
1270 | } | |
1271 | ||
1272 | return 1; | |
1273 | } | |
1274 | ||
1275 | static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, | |
1276 | unsigned long address, pte_t *ptep, pte_t pte, | |
1277 | struct page *pagecache_page) | |
1278 | { | |
1279 | struct page *old_page, *new_page; | |
1280 | int avoidcopy; | |
1281 | int outside_reserve = 0; | |
1282 | ||
1283 | old_page = pte_page(pte); | |
1284 | ||
1285 | retry_avoidcopy: | |
1286 | /* If no-one else is actually using this page, avoid the copy | |
1287 | * and just make the page writable */ | |
1288 | avoidcopy = (page_count(old_page) == 1); | |
1289 | if (avoidcopy) { | |
1290 | set_huge_ptep_writable(vma, address, ptep); | |
1291 | return 0; | |
1292 | } | |
1293 | ||
1294 | /* | |
1295 | * If the process that created a MAP_PRIVATE mapping is about to | |
1296 | * perform a COW due to a shared page count, attempt to satisfy | |
1297 | * the allocation without using the existing reserves. The pagecache | |
1298 | * page is used to determine if the reserve at this address was | |
1299 | * consumed or not. If reserves were used, a partial faulted mapping | |
1300 | * at the time of fork() could consume its reserves on COW instead | |
1301 | * of the full address range. | |
1302 | */ | |
1303 | if (!(vma->vm_flags & VM_SHARED) && | |
1304 | is_vma_resv_set(vma, HPAGE_RESV_OWNER) && | |
1305 | old_page != pagecache_page) | |
1306 | outside_reserve = 1; | |
1307 | ||
1308 | page_cache_get(old_page); | |
1309 | new_page = alloc_huge_page(vma, address, outside_reserve); | |
1310 | ||
1311 | if (IS_ERR(new_page)) { | |
1312 | page_cache_release(old_page); | |
1313 | ||
1314 | /* | |
1315 | * If a process owning a MAP_PRIVATE mapping fails to COW, | |
1316 | * it is due to references held by a child and an insufficient | |
1317 | * huge page pool. To guarantee the original mappers | |
1318 | * reliability, unmap the page from child processes. The child | |
1319 | * may get SIGKILLed if it later faults. | |
1320 | */ | |
1321 | if (outside_reserve) { | |
1322 | BUG_ON(huge_pte_none(pte)); | |
1323 | if (unmap_ref_private(mm, vma, old_page, address)) { | |
1324 | BUG_ON(page_count(old_page) != 1); | |
1325 | BUG_ON(huge_pte_none(pte)); | |
1326 | goto retry_avoidcopy; | |
1327 | } | |
1328 | WARN_ON_ONCE(1); | |
1329 | } | |
1330 | ||
1331 | return -PTR_ERR(new_page); | |
1332 | } | |
1333 | ||
1334 | spin_unlock(&mm->page_table_lock); | |
1335 | copy_huge_page(new_page, old_page, address, vma); | |
1336 | __SetPageUptodate(new_page); | |
1337 | spin_lock(&mm->page_table_lock); | |
1338 | ||
1339 | ptep = huge_pte_offset(mm, address & HPAGE_MASK); | |
1340 | if (likely(pte_same(huge_ptep_get(ptep), pte))) { | |
1341 | /* Break COW */ | |
1342 | huge_ptep_clear_flush(vma, address, ptep); | |
1343 | set_huge_pte_at(mm, address, ptep, | |
1344 | make_huge_pte(vma, new_page, 1)); | |
1345 | /* Make the old page be freed below */ | |
1346 | new_page = old_page; | |
1347 | } | |
1348 | page_cache_release(new_page); | |
1349 | page_cache_release(old_page); | |
1350 | return 0; | |
1351 | } | |
1352 | ||
1353 | /* Return the pagecache page at a given address within a VMA */ | |
1354 | static struct page *hugetlbfs_pagecache_page(struct vm_area_struct *vma, | |
1355 | unsigned long address) | |
1356 | { | |
1357 | struct address_space *mapping; | |
1358 | pgoff_t idx; | |
1359 | ||
1360 | mapping = vma->vm_file->f_mapping; | |
1361 | idx = vma_pagecache_offset(vma, address); | |
1362 | ||
1363 | return find_lock_page(mapping, idx); | |
1364 | } | |
1365 | ||
1366 | static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1367 | unsigned long address, pte_t *ptep, int write_access) | |
1368 | { | |
1369 | int ret = VM_FAULT_SIGBUS; | |
1370 | pgoff_t idx; | |
1371 | unsigned long size; | |
1372 | struct page *page; | |
1373 | struct address_space *mapping; | |
1374 | pte_t new_pte; | |
1375 | ||
1376 | /* | |
1377 | * Currently, we are forced to kill the process in the event the | |
1378 | * original mapper has unmapped pages from the child due to a failed | |
1379 | * COW. Warn that such a situation has occured as it may not be obvious | |
1380 | */ | |
1381 | if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) { | |
1382 | printk(KERN_WARNING | |
1383 | "PID %d killed due to inadequate hugepage pool\n", | |
1384 | current->pid); | |
1385 | return ret; | |
1386 | } | |
1387 | ||
1388 | mapping = vma->vm_file->f_mapping; | |
1389 | idx = vma_pagecache_offset(vma, address); | |
1390 | ||
1391 | /* | |
1392 | * Use page lock to guard against racing truncation | |
1393 | * before we get page_table_lock. | |
1394 | */ | |
1395 | retry: | |
1396 | page = find_lock_page(mapping, idx); | |
1397 | if (!page) { | |
1398 | size = i_size_read(mapping->host) >> HPAGE_SHIFT; | |
1399 | if (idx >= size) | |
1400 | goto out; | |
1401 | page = alloc_huge_page(vma, address, 0); | |
1402 | if (IS_ERR(page)) { | |
1403 | ret = -PTR_ERR(page); | |
1404 | goto out; | |
1405 | } | |
1406 | clear_huge_page(page, address); | |
1407 | __SetPageUptodate(page); | |
1408 | ||
1409 | if (vma->vm_flags & VM_SHARED) { | |
1410 | int err; | |
1411 | struct inode *inode = mapping->host; | |
1412 | ||
1413 | err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); | |
1414 | if (err) { | |
1415 | put_page(page); | |
1416 | if (err == -EEXIST) | |
1417 | goto retry; | |
1418 | goto out; | |
1419 | } | |
1420 | ||
1421 | spin_lock(&inode->i_lock); | |
1422 | inode->i_blocks += BLOCKS_PER_HUGEPAGE; | |
1423 | spin_unlock(&inode->i_lock); | |
1424 | } else | |
1425 | lock_page(page); | |
1426 | } | |
1427 | ||
1428 | spin_lock(&mm->page_table_lock); | |
1429 | size = i_size_read(mapping->host) >> HPAGE_SHIFT; | |
1430 | if (idx >= size) | |
1431 | goto backout; | |
1432 | ||
1433 | ret = 0; | |
1434 | if (!huge_pte_none(huge_ptep_get(ptep))) | |
1435 | goto backout; | |
1436 | ||
1437 | new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) | |
1438 | && (vma->vm_flags & VM_SHARED))); | |
1439 | set_huge_pte_at(mm, address, ptep, new_pte); | |
1440 | ||
1441 | if (write_access && !(vma->vm_flags & VM_SHARED)) { | |
1442 | /* Optimization, do the COW without a second fault */ | |
1443 | ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page); | |
1444 | } | |
1445 | ||
1446 | spin_unlock(&mm->page_table_lock); | |
1447 | unlock_page(page); | |
1448 | out: | |
1449 | return ret; | |
1450 | ||
1451 | backout: | |
1452 | spin_unlock(&mm->page_table_lock); | |
1453 | unlock_page(page); | |
1454 | put_page(page); | |
1455 | goto out; | |
1456 | } | |
1457 | ||
1458 | int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, | |
1459 | unsigned long address, int write_access) | |
1460 | { | |
1461 | pte_t *ptep; | |
1462 | pte_t entry; | |
1463 | int ret; | |
1464 | static DEFINE_MUTEX(hugetlb_instantiation_mutex); | |
1465 | ||
1466 | ptep = huge_pte_alloc(mm, address); | |
1467 | if (!ptep) | |
1468 | return VM_FAULT_OOM; | |
1469 | ||
1470 | /* | |
1471 | * Serialize hugepage allocation and instantiation, so that we don't | |
1472 | * get spurious allocation failures if two CPUs race to instantiate | |
1473 | * the same page in the page cache. | |
1474 | */ | |
1475 | mutex_lock(&hugetlb_instantiation_mutex); | |
1476 | entry = huge_ptep_get(ptep); | |
1477 | if (huge_pte_none(entry)) { | |
1478 | ret = hugetlb_no_page(mm, vma, address, ptep, write_access); | |
1479 | mutex_unlock(&hugetlb_instantiation_mutex); | |
1480 | return ret; | |
1481 | } | |
1482 | ||
1483 | ret = 0; | |
1484 | ||
1485 | spin_lock(&mm->page_table_lock); | |
1486 | /* Check for a racing update before calling hugetlb_cow */ | |
1487 | if (likely(pte_same(entry, huge_ptep_get(ptep)))) | |
1488 | if (write_access && !pte_write(entry)) { | |
1489 | struct page *page; | |
1490 | page = hugetlbfs_pagecache_page(vma, address); | |
1491 | ret = hugetlb_cow(mm, vma, address, ptep, entry, page); | |
1492 | if (page) { | |
1493 | unlock_page(page); | |
1494 | put_page(page); | |
1495 | } | |
1496 | } | |
1497 | spin_unlock(&mm->page_table_lock); | |
1498 | mutex_unlock(&hugetlb_instantiation_mutex); | |
1499 | ||
1500 | return ret; | |
1501 | } | |
1502 | ||
1503 | int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
1504 | struct page **pages, struct vm_area_struct **vmas, | |
1505 | unsigned long *position, int *length, int i, | |
1506 | int write) | |
1507 | { | |
1508 | unsigned long pfn_offset; | |
1509 | unsigned long vaddr = *position; | |
1510 | int remainder = *length; | |
1511 | ||
1512 | spin_lock(&mm->page_table_lock); | |
1513 | while (vaddr < vma->vm_end && remainder) { | |
1514 | pte_t *pte; | |
1515 | struct page *page; | |
1516 | ||
1517 | /* | |
1518 | * Some archs (sparc64, sh*) have multiple pte_ts to | |
1519 | * each hugepage. We have to make * sure we get the | |
1520 | * first, for the page indexing below to work. | |
1521 | */ | |
1522 | pte = huge_pte_offset(mm, vaddr & HPAGE_MASK); | |
1523 | ||
1524 | if (!pte || huge_pte_none(huge_ptep_get(pte)) || | |
1525 | (write && !pte_write(huge_ptep_get(pte)))) { | |
1526 | int ret; | |
1527 | ||
1528 | spin_unlock(&mm->page_table_lock); | |
1529 | ret = hugetlb_fault(mm, vma, vaddr, write); | |
1530 | spin_lock(&mm->page_table_lock); | |
1531 | if (!(ret & VM_FAULT_ERROR)) | |
1532 | continue; | |
1533 | ||
1534 | remainder = 0; | |
1535 | if (!i) | |
1536 | i = -EFAULT; | |
1537 | break; | |
1538 | } | |
1539 | ||
1540 | pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT; | |
1541 | page = pte_page(huge_ptep_get(pte)); | |
1542 | same_page: | |
1543 | if (pages) { | |
1544 | get_page(page); | |
1545 | pages[i] = page + pfn_offset; | |
1546 | } | |
1547 | ||
1548 | if (vmas) | |
1549 | vmas[i] = vma; | |
1550 | ||
1551 | vaddr += PAGE_SIZE; | |
1552 | ++pfn_offset; | |
1553 | --remainder; | |
1554 | ++i; | |
1555 | if (vaddr < vma->vm_end && remainder && | |
1556 | pfn_offset < HPAGE_SIZE/PAGE_SIZE) { | |
1557 | /* | |
1558 | * We use pfn_offset to avoid touching the pageframes | |
1559 | * of this compound page. | |
1560 | */ | |
1561 | goto same_page; | |
1562 | } | |
1563 | } | |
1564 | spin_unlock(&mm->page_table_lock); | |
1565 | *length = remainder; | |
1566 | *position = vaddr; | |
1567 | ||
1568 | return i; | |
1569 | } | |
1570 | ||
1571 | void hugetlb_change_protection(struct vm_area_struct *vma, | |
1572 | unsigned long address, unsigned long end, pgprot_t newprot) | |
1573 | { | |
1574 | struct mm_struct *mm = vma->vm_mm; | |
1575 | unsigned long start = address; | |
1576 | pte_t *ptep; | |
1577 | pte_t pte; | |
1578 | ||
1579 | BUG_ON(address >= end); | |
1580 | flush_cache_range(vma, address, end); | |
1581 | ||
1582 | spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); | |
1583 | spin_lock(&mm->page_table_lock); | |
1584 | for (; address < end; address += HPAGE_SIZE) { | |
1585 | ptep = huge_pte_offset(mm, address); | |
1586 | if (!ptep) | |
1587 | continue; | |
1588 | if (huge_pmd_unshare(mm, &address, ptep)) | |
1589 | continue; | |
1590 | if (!huge_pte_none(huge_ptep_get(ptep))) { | |
1591 | pte = huge_ptep_get_and_clear(mm, address, ptep); | |
1592 | pte = pte_mkhuge(pte_modify(pte, newprot)); | |
1593 | set_huge_pte_at(mm, address, ptep, pte); | |
1594 | } | |
1595 | } | |
1596 | spin_unlock(&mm->page_table_lock); | |
1597 | spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); | |
1598 | ||
1599 | flush_tlb_range(vma, start, end); | |
1600 | } | |
1601 | ||
1602 | int hugetlb_reserve_pages(struct inode *inode, | |
1603 | long from, long to, | |
1604 | struct vm_area_struct *vma) | |
1605 | { | |
1606 | long ret, chg; | |
1607 | ||
1608 | if (vma && vma->vm_flags & VM_NORESERVE) | |
1609 | return 0; | |
1610 | ||
1611 | /* | |
1612 | * Shared mappings base their reservation on the number of pages that | |
1613 | * are already allocated on behalf of the file. Private mappings need | |
1614 | * to reserve the full area even if read-only as mprotect() may be | |
1615 | * called to make the mapping read-write. Assume !vma is a shm mapping | |
1616 | */ | |
1617 | if (!vma || vma->vm_flags & VM_SHARED) | |
1618 | chg = region_chg(&inode->i_mapping->private_list, from, to); | |
1619 | else { | |
1620 | chg = to - from; | |
1621 | set_vma_resv_huge_pages(vma, chg); | |
1622 | set_vma_resv_flags(vma, HPAGE_RESV_OWNER); | |
1623 | } | |
1624 | ||
1625 | if (chg < 0) | |
1626 | return chg; | |
1627 | ||
1628 | if (hugetlb_get_quota(inode->i_mapping, chg)) | |
1629 | return -ENOSPC; | |
1630 | ret = hugetlb_acct_memory(chg); | |
1631 | if (ret < 0) { | |
1632 | hugetlb_put_quota(inode->i_mapping, chg); | |
1633 | return ret; | |
1634 | } | |
1635 | if (!vma || vma->vm_flags & VM_SHARED) | |
1636 | region_add(&inode->i_mapping->private_list, from, to); | |
1637 | return 0; | |
1638 | } | |
1639 | ||
1640 | void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) | |
1641 | { | |
1642 | long chg = region_truncate(&inode->i_mapping->private_list, offset); | |
1643 | ||
1644 | spin_lock(&inode->i_lock); | |
1645 | inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed; | |
1646 | spin_unlock(&inode->i_lock); | |
1647 | ||
1648 | hugetlb_put_quota(inode->i_mapping, (chg - freed)); | |
1649 | hugetlb_acct_memory(-(chg - freed)); | |
1650 | } |