Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * High memory handling common code and variables. | |
3 | * | |
4 | * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de | |
5 | * Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de | |
6 | * | |
7 | * | |
8 | * Redesigned the x86 32-bit VM architecture to deal with | |
9 | * 64-bit physical space. With current x86 CPUs this | |
10 | * means up to 64 Gigabytes physical RAM. | |
11 | * | |
12 | * Rewrote high memory support to move the page cache into | |
13 | * high memory. Implemented permanent (schedulable) kmaps | |
14 | * based on Linus' idea. | |
15 | * | |
16 | * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com> | |
17 | */ | |
18 | ||
19 | #include <linux/mm.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/swap.h> | |
22 | #include <linux/bio.h> | |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/mempool.h> | |
25 | #include <linux/blkdev.h> | |
26 | #include <linux/init.h> | |
27 | #include <linux/hash.h> | |
28 | #include <linux/highmem.h> | |
2056a782 | 29 | #include <linux/blktrace_api.h> |
1da177e4 LT |
30 | #include <asm/tlbflush.h> |
31 | ||
32 | static mempool_t *page_pool, *isa_page_pool; | |
33 | ||
260b2367 | 34 | static void *page_pool_alloc_isa(gfp_t gfp_mask, void *data) |
1da177e4 | 35 | { |
260b2367 | 36 | return alloc_page(gfp_mask | GFP_DMA); |
1da177e4 LT |
37 | } |
38 | ||
39 | static void page_pool_free(void *page, void *data) | |
40 | { | |
41 | __free_page(page); | |
42 | } | |
43 | ||
44 | /* | |
45 | * Virtual_count is not a pure "count". | |
46 | * 0 means that it is not mapped, and has not been mapped | |
47 | * since a TLB flush - it is usable. | |
48 | * 1 means that there are no users, but it has been mapped | |
49 | * since the last TLB flush - so we can't use it. | |
50 | * n means that there are (n-1) current users of it. | |
51 | */ | |
52 | #ifdef CONFIG_HIGHMEM | |
260b2367 AV |
53 | |
54 | static void *page_pool_alloc(gfp_t gfp_mask, void *data) | |
55 | { | |
56 | return alloc_page(gfp_mask); | |
57 | } | |
58 | ||
1da177e4 LT |
59 | static int pkmap_count[LAST_PKMAP]; |
60 | static unsigned int last_pkmap_nr; | |
61 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(kmap_lock); | |
62 | ||
63 | pte_t * pkmap_page_table; | |
64 | ||
65 | static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); | |
66 | ||
67 | static void flush_all_zero_pkmaps(void) | |
68 | { | |
69 | int i; | |
70 | ||
71 | flush_cache_kmaps(); | |
72 | ||
73 | for (i = 0; i < LAST_PKMAP; i++) { | |
74 | struct page *page; | |
75 | ||
76 | /* | |
77 | * zero means we don't have anything to do, | |
78 | * >1 means that it is still in use. Only | |
79 | * a count of 1 means that it is free but | |
80 | * needs to be unmapped | |
81 | */ | |
82 | if (pkmap_count[i] != 1) | |
83 | continue; | |
84 | pkmap_count[i] = 0; | |
85 | ||
86 | /* sanity check */ | |
87 | if (pte_none(pkmap_page_table[i])) | |
88 | BUG(); | |
89 | ||
90 | /* | |
91 | * Don't need an atomic fetch-and-clear op here; | |
92 | * no-one has the page mapped, and cannot get at | |
93 | * its virtual address (and hence PTE) without first | |
94 | * getting the kmap_lock (which is held here). | |
95 | * So no dangers, even with speculative execution. | |
96 | */ | |
97 | page = pte_page(pkmap_page_table[i]); | |
98 | pte_clear(&init_mm, (unsigned long)page_address(page), | |
99 | &pkmap_page_table[i]); | |
100 | ||
101 | set_page_address(page, NULL); | |
102 | } | |
103 | flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP)); | |
104 | } | |
105 | ||
106 | static inline unsigned long map_new_virtual(struct page *page) | |
107 | { | |
108 | unsigned long vaddr; | |
109 | int count; | |
110 | ||
111 | start: | |
112 | count = LAST_PKMAP; | |
113 | /* Find an empty entry */ | |
114 | for (;;) { | |
115 | last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK; | |
116 | if (!last_pkmap_nr) { | |
117 | flush_all_zero_pkmaps(); | |
118 | count = LAST_PKMAP; | |
119 | } | |
120 | if (!pkmap_count[last_pkmap_nr]) | |
121 | break; /* Found a usable entry */ | |
122 | if (--count) | |
123 | continue; | |
124 | ||
125 | /* | |
126 | * Sleep for somebody else to unmap their entries | |
127 | */ | |
128 | { | |
129 | DECLARE_WAITQUEUE(wait, current); | |
130 | ||
131 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
132 | add_wait_queue(&pkmap_map_wait, &wait); | |
133 | spin_unlock(&kmap_lock); | |
134 | schedule(); | |
135 | remove_wait_queue(&pkmap_map_wait, &wait); | |
136 | spin_lock(&kmap_lock); | |
137 | ||
138 | /* Somebody else might have mapped it while we slept */ | |
139 | if (page_address(page)) | |
140 | return (unsigned long)page_address(page); | |
141 | ||
142 | /* Re-start */ | |
143 | goto start; | |
144 | } | |
145 | } | |
146 | vaddr = PKMAP_ADDR(last_pkmap_nr); | |
147 | set_pte_at(&init_mm, vaddr, | |
148 | &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot)); | |
149 | ||
150 | pkmap_count[last_pkmap_nr] = 1; | |
151 | set_page_address(page, (void *)vaddr); | |
152 | ||
153 | return vaddr; | |
154 | } | |
155 | ||
156 | void fastcall *kmap_high(struct page *page) | |
157 | { | |
158 | unsigned long vaddr; | |
159 | ||
160 | /* | |
161 | * For highmem pages, we can't trust "virtual" until | |
162 | * after we have the lock. | |
163 | * | |
164 | * We cannot call this from interrupts, as it may block | |
165 | */ | |
166 | spin_lock(&kmap_lock); | |
167 | vaddr = (unsigned long)page_address(page); | |
168 | if (!vaddr) | |
169 | vaddr = map_new_virtual(page); | |
170 | pkmap_count[PKMAP_NR(vaddr)]++; | |
171 | if (pkmap_count[PKMAP_NR(vaddr)] < 2) | |
172 | BUG(); | |
173 | spin_unlock(&kmap_lock); | |
174 | return (void*) vaddr; | |
175 | } | |
176 | ||
177 | EXPORT_SYMBOL(kmap_high); | |
178 | ||
179 | void fastcall kunmap_high(struct page *page) | |
180 | { | |
181 | unsigned long vaddr; | |
182 | unsigned long nr; | |
183 | int need_wakeup; | |
184 | ||
185 | spin_lock(&kmap_lock); | |
186 | vaddr = (unsigned long)page_address(page); | |
187 | if (!vaddr) | |
188 | BUG(); | |
189 | nr = PKMAP_NR(vaddr); | |
190 | ||
191 | /* | |
192 | * A count must never go down to zero | |
193 | * without a TLB flush! | |
194 | */ | |
195 | need_wakeup = 0; | |
196 | switch (--pkmap_count[nr]) { | |
197 | case 0: | |
198 | BUG(); | |
199 | case 1: | |
200 | /* | |
201 | * Avoid an unnecessary wake_up() function call. | |
202 | * The common case is pkmap_count[] == 1, but | |
203 | * no waiters. | |
204 | * The tasks queued in the wait-queue are guarded | |
205 | * by both the lock in the wait-queue-head and by | |
206 | * the kmap_lock. As the kmap_lock is held here, | |
207 | * no need for the wait-queue-head's lock. Simply | |
208 | * test if the queue is empty. | |
209 | */ | |
210 | need_wakeup = waitqueue_active(&pkmap_map_wait); | |
211 | } | |
212 | spin_unlock(&kmap_lock); | |
213 | ||
214 | /* do wake-up, if needed, race-free outside of the spin lock */ | |
215 | if (need_wakeup) | |
216 | wake_up(&pkmap_map_wait); | |
217 | } | |
218 | ||
219 | EXPORT_SYMBOL(kunmap_high); | |
220 | ||
221 | #define POOL_SIZE 64 | |
222 | ||
223 | static __init int init_emergency_pool(void) | |
224 | { | |
225 | struct sysinfo i; | |
226 | si_meminfo(&i); | |
227 | si_swapinfo(&i); | |
228 | ||
229 | if (!i.totalhigh) | |
230 | return 0; | |
231 | ||
232 | page_pool = mempool_create(POOL_SIZE, page_pool_alloc, page_pool_free, NULL); | |
233 | if (!page_pool) | |
234 | BUG(); | |
235 | printk("highmem bounce pool size: %d pages\n", POOL_SIZE); | |
236 | ||
237 | return 0; | |
238 | } | |
239 | ||
240 | __initcall(init_emergency_pool); | |
241 | ||
242 | /* | |
243 | * highmem version, map in to vec | |
244 | */ | |
245 | static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom) | |
246 | { | |
247 | unsigned long flags; | |
248 | unsigned char *vto; | |
249 | ||
250 | local_irq_save(flags); | |
251 | vto = kmap_atomic(to->bv_page, KM_BOUNCE_READ); | |
252 | memcpy(vto + to->bv_offset, vfrom, to->bv_len); | |
253 | kunmap_atomic(vto, KM_BOUNCE_READ); | |
254 | local_irq_restore(flags); | |
255 | } | |
256 | ||
257 | #else /* CONFIG_HIGHMEM */ | |
258 | ||
259 | #define bounce_copy_vec(to, vfrom) \ | |
260 | memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len) | |
261 | ||
262 | #endif | |
263 | ||
264 | #define ISA_POOL_SIZE 16 | |
265 | ||
266 | /* | |
267 | * gets called "every" time someone init's a queue with BLK_BOUNCE_ISA | |
268 | * as the max address, so check if the pool has already been created. | |
269 | */ | |
270 | int init_emergency_isa_pool(void) | |
271 | { | |
272 | if (isa_page_pool) | |
273 | return 0; | |
274 | ||
260b2367 | 275 | isa_page_pool = mempool_create(ISA_POOL_SIZE, page_pool_alloc_isa, page_pool_free, NULL); |
1da177e4 LT |
276 | if (!isa_page_pool) |
277 | BUG(); | |
278 | ||
279 | printk("isa bounce pool size: %d pages\n", ISA_POOL_SIZE); | |
280 | return 0; | |
281 | } | |
282 | ||
283 | /* | |
284 | * Simple bounce buffer support for highmem pages. Depending on the | |
285 | * queue gfp mask set, *to may or may not be a highmem page. kmap it | |
286 | * always, it will do the Right Thing | |
287 | */ | |
288 | static void copy_to_high_bio_irq(struct bio *to, struct bio *from) | |
289 | { | |
290 | unsigned char *vfrom; | |
291 | struct bio_vec *tovec, *fromvec; | |
292 | int i; | |
293 | ||
294 | __bio_for_each_segment(tovec, to, i, 0) { | |
295 | fromvec = from->bi_io_vec + i; | |
296 | ||
297 | /* | |
298 | * not bounced | |
299 | */ | |
300 | if (tovec->bv_page == fromvec->bv_page) | |
301 | continue; | |
302 | ||
303 | /* | |
304 | * fromvec->bv_offset and fromvec->bv_len might have been | |
305 | * modified by the block layer, so use the original copy, | |
306 | * bounce_copy_vec already uses tovec->bv_len | |
307 | */ | |
308 | vfrom = page_address(fromvec->bv_page) + tovec->bv_offset; | |
309 | ||
310 | flush_dcache_page(tovec->bv_page); | |
311 | bounce_copy_vec(tovec, vfrom); | |
312 | } | |
313 | } | |
314 | ||
315 | static void bounce_end_io(struct bio *bio, mempool_t *pool, int err) | |
316 | { | |
317 | struct bio *bio_orig = bio->bi_private; | |
318 | struct bio_vec *bvec, *org_vec; | |
319 | int i; | |
320 | ||
321 | if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags)) | |
322 | set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags); | |
323 | ||
324 | /* | |
325 | * free up bounce indirect pages used | |
326 | */ | |
327 | __bio_for_each_segment(bvec, bio, i, 0) { | |
328 | org_vec = bio_orig->bi_io_vec + i; | |
329 | if (bvec->bv_page == org_vec->bv_page) | |
330 | continue; | |
331 | ||
332 | mempool_free(bvec->bv_page, pool); | |
edfbe2b0 | 333 | dec_page_state(nr_bounce); |
1da177e4 LT |
334 | } |
335 | ||
336 | bio_endio(bio_orig, bio_orig->bi_size, err); | |
337 | bio_put(bio); | |
338 | } | |
339 | ||
340 | static int bounce_end_io_write(struct bio *bio, unsigned int bytes_done,int err) | |
341 | { | |
342 | if (bio->bi_size) | |
343 | return 1; | |
344 | ||
345 | bounce_end_io(bio, page_pool, err); | |
346 | return 0; | |
347 | } | |
348 | ||
349 | static int bounce_end_io_write_isa(struct bio *bio, unsigned int bytes_done, int err) | |
350 | { | |
351 | if (bio->bi_size) | |
352 | return 1; | |
353 | ||
354 | bounce_end_io(bio, isa_page_pool, err); | |
355 | return 0; | |
356 | } | |
357 | ||
358 | static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err) | |
359 | { | |
360 | struct bio *bio_orig = bio->bi_private; | |
361 | ||
362 | if (test_bit(BIO_UPTODATE, &bio->bi_flags)) | |
363 | copy_to_high_bio_irq(bio_orig, bio); | |
364 | ||
365 | bounce_end_io(bio, pool, err); | |
366 | } | |
367 | ||
368 | static int bounce_end_io_read(struct bio *bio, unsigned int bytes_done, int err) | |
369 | { | |
370 | if (bio->bi_size) | |
371 | return 1; | |
372 | ||
373 | __bounce_end_io_read(bio, page_pool, err); | |
374 | return 0; | |
375 | } | |
376 | ||
377 | static int bounce_end_io_read_isa(struct bio *bio, unsigned int bytes_done, int err) | |
378 | { | |
379 | if (bio->bi_size) | |
380 | return 1; | |
381 | ||
382 | __bounce_end_io_read(bio, isa_page_pool, err); | |
383 | return 0; | |
384 | } | |
385 | ||
386 | static void __blk_queue_bounce(request_queue_t *q, struct bio **bio_orig, | |
387 | mempool_t *pool) | |
388 | { | |
389 | struct page *page; | |
390 | struct bio *bio = NULL; | |
391 | int i, rw = bio_data_dir(*bio_orig); | |
392 | struct bio_vec *to, *from; | |
393 | ||
394 | bio_for_each_segment(from, *bio_orig, i) { | |
395 | page = from->bv_page; | |
396 | ||
397 | /* | |
398 | * is destination page below bounce pfn? | |
399 | */ | |
400 | if (page_to_pfn(page) < q->bounce_pfn) | |
401 | continue; | |
402 | ||
403 | /* | |
404 | * irk, bounce it | |
405 | */ | |
406 | if (!bio) | |
407 | bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt); | |
408 | ||
409 | to = bio->bi_io_vec + i; | |
410 | ||
411 | to->bv_page = mempool_alloc(pool, q->bounce_gfp); | |
412 | to->bv_len = from->bv_len; | |
413 | to->bv_offset = from->bv_offset; | |
edfbe2b0 | 414 | inc_page_state(nr_bounce); |
1da177e4 LT |
415 | |
416 | if (rw == WRITE) { | |
417 | char *vto, *vfrom; | |
418 | ||
419 | flush_dcache_page(from->bv_page); | |
420 | vto = page_address(to->bv_page) + to->bv_offset; | |
421 | vfrom = kmap(from->bv_page) + from->bv_offset; | |
422 | memcpy(vto, vfrom, to->bv_len); | |
423 | kunmap(from->bv_page); | |
424 | } | |
425 | } | |
426 | ||
427 | /* | |
428 | * no pages bounced | |
429 | */ | |
430 | if (!bio) | |
431 | return; | |
432 | ||
433 | /* | |
434 | * at least one page was bounced, fill in possible non-highmem | |
435 | * pages | |
436 | */ | |
437 | __bio_for_each_segment(from, *bio_orig, i, 0) { | |
438 | to = bio_iovec_idx(bio, i); | |
439 | if (!to->bv_page) { | |
440 | to->bv_page = from->bv_page; | |
441 | to->bv_len = from->bv_len; | |
442 | to->bv_offset = from->bv_offset; | |
443 | } | |
444 | } | |
445 | ||
446 | bio->bi_bdev = (*bio_orig)->bi_bdev; | |
447 | bio->bi_flags |= (1 << BIO_BOUNCED); | |
448 | bio->bi_sector = (*bio_orig)->bi_sector; | |
449 | bio->bi_rw = (*bio_orig)->bi_rw; | |
450 | ||
451 | bio->bi_vcnt = (*bio_orig)->bi_vcnt; | |
452 | bio->bi_idx = (*bio_orig)->bi_idx; | |
453 | bio->bi_size = (*bio_orig)->bi_size; | |
454 | ||
455 | if (pool == page_pool) { | |
456 | bio->bi_end_io = bounce_end_io_write; | |
457 | if (rw == READ) | |
458 | bio->bi_end_io = bounce_end_io_read; | |
459 | } else { | |
460 | bio->bi_end_io = bounce_end_io_write_isa; | |
461 | if (rw == READ) | |
462 | bio->bi_end_io = bounce_end_io_read_isa; | |
463 | } | |
464 | ||
465 | bio->bi_private = *bio_orig; | |
466 | *bio_orig = bio; | |
467 | } | |
468 | ||
469 | void blk_queue_bounce(request_queue_t *q, struct bio **bio_orig) | |
470 | { | |
471 | mempool_t *pool; | |
472 | ||
473 | /* | |
474 | * for non-isa bounce case, just check if the bounce pfn is equal | |
475 | * to or bigger than the highest pfn in the system -- in that case, | |
476 | * don't waste time iterating over bio segments | |
477 | */ | |
478 | if (!(q->bounce_gfp & GFP_DMA)) { | |
479 | if (q->bounce_pfn >= blk_max_pfn) | |
480 | return; | |
481 | pool = page_pool; | |
482 | } else { | |
483 | BUG_ON(!isa_page_pool); | |
484 | pool = isa_page_pool; | |
485 | } | |
486 | ||
2056a782 JA |
487 | blk_add_trace_bio(q, *bio_orig, BLK_TA_BOUNCE); |
488 | ||
1da177e4 LT |
489 | /* |
490 | * slow path | |
491 | */ | |
492 | __blk_queue_bounce(q, bio_orig, pool); | |
493 | } | |
494 | ||
495 | EXPORT_SYMBOL(blk_queue_bounce); | |
496 | ||
497 | #if defined(HASHED_PAGE_VIRTUAL) | |
498 | ||
499 | #define PA_HASH_ORDER 7 | |
500 | ||
501 | /* | |
502 | * Describes one page->virtual association | |
503 | */ | |
504 | struct page_address_map { | |
505 | struct page *page; | |
506 | void *virtual; | |
507 | struct list_head list; | |
508 | }; | |
509 | ||
510 | /* | |
511 | * page_address_map freelist, allocated from page_address_maps. | |
512 | */ | |
513 | static struct list_head page_address_pool; /* freelist */ | |
514 | static spinlock_t pool_lock; /* protects page_address_pool */ | |
515 | ||
516 | /* | |
517 | * Hash table bucket | |
518 | */ | |
519 | static struct page_address_slot { | |
520 | struct list_head lh; /* List of page_address_maps */ | |
521 | spinlock_t lock; /* Protect this bucket's list */ | |
522 | } ____cacheline_aligned_in_smp page_address_htable[1<<PA_HASH_ORDER]; | |
523 | ||
524 | static struct page_address_slot *page_slot(struct page *page) | |
525 | { | |
526 | return &page_address_htable[hash_ptr(page, PA_HASH_ORDER)]; | |
527 | } | |
528 | ||
529 | void *page_address(struct page *page) | |
530 | { | |
531 | unsigned long flags; | |
532 | void *ret; | |
533 | struct page_address_slot *pas; | |
534 | ||
535 | if (!PageHighMem(page)) | |
536 | return lowmem_page_address(page); | |
537 | ||
538 | pas = page_slot(page); | |
539 | ret = NULL; | |
540 | spin_lock_irqsave(&pas->lock, flags); | |
541 | if (!list_empty(&pas->lh)) { | |
542 | struct page_address_map *pam; | |
543 | ||
544 | list_for_each_entry(pam, &pas->lh, list) { | |
545 | if (pam->page == page) { | |
546 | ret = pam->virtual; | |
547 | goto done; | |
548 | } | |
549 | } | |
550 | } | |
551 | done: | |
552 | spin_unlock_irqrestore(&pas->lock, flags); | |
553 | return ret; | |
554 | } | |
555 | ||
556 | EXPORT_SYMBOL(page_address); | |
557 | ||
558 | void set_page_address(struct page *page, void *virtual) | |
559 | { | |
560 | unsigned long flags; | |
561 | struct page_address_slot *pas; | |
562 | struct page_address_map *pam; | |
563 | ||
564 | BUG_ON(!PageHighMem(page)); | |
565 | ||
566 | pas = page_slot(page); | |
567 | if (virtual) { /* Add */ | |
568 | BUG_ON(list_empty(&page_address_pool)); | |
569 | ||
570 | spin_lock_irqsave(&pool_lock, flags); | |
571 | pam = list_entry(page_address_pool.next, | |
572 | struct page_address_map, list); | |
573 | list_del(&pam->list); | |
574 | spin_unlock_irqrestore(&pool_lock, flags); | |
575 | ||
576 | pam->page = page; | |
577 | pam->virtual = virtual; | |
578 | ||
579 | spin_lock_irqsave(&pas->lock, flags); | |
580 | list_add_tail(&pam->list, &pas->lh); | |
581 | spin_unlock_irqrestore(&pas->lock, flags); | |
582 | } else { /* Remove */ | |
583 | spin_lock_irqsave(&pas->lock, flags); | |
584 | list_for_each_entry(pam, &pas->lh, list) { | |
585 | if (pam->page == page) { | |
586 | list_del(&pam->list); | |
587 | spin_unlock_irqrestore(&pas->lock, flags); | |
588 | spin_lock_irqsave(&pool_lock, flags); | |
589 | list_add_tail(&pam->list, &page_address_pool); | |
590 | spin_unlock_irqrestore(&pool_lock, flags); | |
591 | goto done; | |
592 | } | |
593 | } | |
594 | spin_unlock_irqrestore(&pas->lock, flags); | |
595 | } | |
596 | done: | |
597 | return; | |
598 | } | |
599 | ||
600 | static struct page_address_map page_address_maps[LAST_PKMAP]; | |
601 | ||
602 | void __init page_address_init(void) | |
603 | { | |
604 | int i; | |
605 | ||
606 | INIT_LIST_HEAD(&page_address_pool); | |
607 | for (i = 0; i < ARRAY_SIZE(page_address_maps); i++) | |
608 | list_add(&page_address_maps[i].list, &page_address_pool); | |
609 | for (i = 0; i < ARRAY_SIZE(page_address_htable); i++) { | |
610 | INIT_LIST_HEAD(&page_address_htable[i].lh); | |
611 | spin_lock_init(&page_address_htable[i].lock); | |
612 | } | |
613 | spin_lock_init(&pool_lock); | |
614 | } | |
615 | ||
616 | #endif /* defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL) */ |