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mm: avoid marking swap cached page as lazyfree
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CommitLineData
1da177e4
LT
1/*
2 * linux/mm/swap_state.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 * Swap reorganised 29.12.95, Stephen Tweedie
6 *
7 * Rewritten to use page cache, (C) 1998 Stephen Tweedie
8 */
1da177e4 9#include <linux/mm.h>
5a0e3ad6 10#include <linux/gfp.h>
1da177e4
LT
11#include <linux/kernel_stat.h>
12#include <linux/swap.h>
46017e95 13#include <linux/swapops.h>
1da177e4
LT
14#include <linux/init.h>
15#include <linux/pagemap.h>
1da177e4 16#include <linux/backing-dev.h>
3fb5c298 17#include <linux/blkdev.h>
c484d410 18#include <linux/pagevec.h>
b20a3503 19#include <linux/migrate.h>
4b3ef9da 20#include <linux/vmalloc.h>
67afa38e 21#include <linux/swap_slots.h>
38d8b4e6 22#include <linux/huge_mm.h>
1da177e4
LT
23
24#include <asm/pgtable.h>
25
26/*
27 * swapper_space is a fiction, retained to simplify the path through
7eaceacc 28 * vmscan's shrink_page_list.
1da177e4 29 */
f5e54d6e 30static const struct address_space_operations swap_aops = {
1da177e4 31 .writepage = swap_writepage,
62c230bc 32 .set_page_dirty = swap_set_page_dirty,
1c93923c 33#ifdef CONFIG_MIGRATION
e965f963 34 .migratepage = migrate_page,
1c93923c 35#endif
1da177e4
LT
36};
37
4b3ef9da
HY
38struct address_space *swapper_spaces[MAX_SWAPFILES];
39static unsigned int nr_swapper_spaces[MAX_SWAPFILES];
ec560175
HY
40bool swap_vma_readahead = true;
41
42#define SWAP_RA_MAX_ORDER_DEFAULT 3
43
44static int swap_ra_max_order = SWAP_RA_MAX_ORDER_DEFAULT;
45
46#define SWAP_RA_WIN_SHIFT (PAGE_SHIFT / 2)
47#define SWAP_RA_HITS_MASK ((1UL << SWAP_RA_WIN_SHIFT) - 1)
48#define SWAP_RA_HITS_MAX SWAP_RA_HITS_MASK
49#define SWAP_RA_WIN_MASK (~PAGE_MASK & ~SWAP_RA_HITS_MASK)
50
51#define SWAP_RA_HITS(v) ((v) & SWAP_RA_HITS_MASK)
52#define SWAP_RA_WIN(v) (((v) & SWAP_RA_WIN_MASK) >> SWAP_RA_WIN_SHIFT)
53#define SWAP_RA_ADDR(v) ((v) & PAGE_MASK)
54
55#define SWAP_RA_VAL(addr, win, hits) \
56 (((addr) & PAGE_MASK) | \
57 (((win) << SWAP_RA_WIN_SHIFT) & SWAP_RA_WIN_MASK) | \
58 ((hits) & SWAP_RA_HITS_MASK))
59
60/* Initial readahead hits is 4 to start up with a small window */
61#define GET_SWAP_RA_VAL(vma) \
62 (atomic_long_read(&(vma)->swap_readahead_info) ? : 4)
1da177e4
LT
63
64#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0)
38d8b4e6 65#define ADD_CACHE_INFO(x, nr) do { swap_cache_info.x += (nr); } while (0)
1da177e4
LT
66
67static struct {
68 unsigned long add_total;
69 unsigned long del_total;
70 unsigned long find_success;
71 unsigned long find_total;
1da177e4
LT
72} swap_cache_info;
73
33806f06
SL
74unsigned long total_swapcache_pages(void)
75{
4b3ef9da 76 unsigned int i, j, nr;
33806f06 77 unsigned long ret = 0;
4b3ef9da 78 struct address_space *spaces;
33806f06 79
4b3ef9da
HY
80 rcu_read_lock();
81 for (i = 0; i < MAX_SWAPFILES; i++) {
82 /*
83 * The corresponding entries in nr_swapper_spaces and
84 * swapper_spaces will be reused only after at least
85 * one grace period. So it is impossible for them
86 * belongs to different usage.
87 */
88 nr = nr_swapper_spaces[i];
89 spaces = rcu_dereference(swapper_spaces[i]);
90 if (!nr || !spaces)
91 continue;
92 for (j = 0; j < nr; j++)
93 ret += spaces[j].nrpages;
94 }
95 rcu_read_unlock();
33806f06
SL
96 return ret;
97}
98
579f8290
SL
99static atomic_t swapin_readahead_hits = ATOMIC_INIT(4);
100
1da177e4
LT
101void show_swap_cache_info(void)
102{
33806f06 103 printk("%lu pages in swap cache\n", total_swapcache_pages());
2c97b7fc 104 printk("Swap cache stats: add %lu, delete %lu, find %lu/%lu\n",
1da177e4 105 swap_cache_info.add_total, swap_cache_info.del_total,
bb63be0a 106 swap_cache_info.find_success, swap_cache_info.find_total);
ec8acf20
SL
107 printk("Free swap = %ldkB\n",
108 get_nr_swap_pages() << (PAGE_SHIFT - 10));
1da177e4
LT
109 printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
110}
111
112/*
31a56396 113 * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
1da177e4
LT
114 * but sets SwapCache flag and private instead of mapping and index.
115 */
2f772e6c 116int __add_to_swap_cache(struct page *page, swp_entry_t entry)
1da177e4 117{
38d8b4e6 118 int error, i, nr = hpage_nr_pages(page);
33806f06 119 struct address_space *address_space;
38d8b4e6 120 pgoff_t idx = swp_offset(entry);
1da177e4 121
309381fe
SL
122 VM_BUG_ON_PAGE(!PageLocked(page), page);
123 VM_BUG_ON_PAGE(PageSwapCache(page), page);
124 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
51726b12 125
38d8b4e6 126 page_ref_add(page, nr);
31a56396 127 SetPageSwapCache(page);
31a56396 128
33806f06
SL
129 address_space = swap_address_space(entry);
130 spin_lock_irq(&address_space->tree_lock);
38d8b4e6
HY
131 for (i = 0; i < nr; i++) {
132 set_page_private(page + i, entry.val + i);
133 error = radix_tree_insert(&address_space->page_tree,
134 idx + i, page + i);
135 if (unlikely(error))
136 break;
31a56396 137 }
38d8b4e6
HY
138 if (likely(!error)) {
139 address_space->nrpages += nr;
140 __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
141 ADD_CACHE_INFO(add_total, nr);
142 } else {
2ca4532a
DN
143 /*
144 * Only the context which have set SWAP_HAS_CACHE flag
145 * would call add_to_swap_cache().
146 * So add_to_swap_cache() doesn't returns -EEXIST.
147 */
148 VM_BUG_ON(error == -EEXIST);
38d8b4e6
HY
149 set_page_private(page + i, 0UL);
150 while (i--) {
151 radix_tree_delete(&address_space->page_tree, idx + i);
152 set_page_private(page + i, 0UL);
153 }
31a56396 154 ClearPageSwapCache(page);
38d8b4e6 155 page_ref_sub(page, nr);
31a56396 156 }
38d8b4e6 157 spin_unlock_irq(&address_space->tree_lock);
31a56396
DN
158
159 return error;
160}
161
162
163int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
164{
165 int error;
166
38d8b4e6 167 error = radix_tree_maybe_preload_order(gfp_mask, compound_order(page));
35c754d7 168 if (!error) {
31a56396 169 error = __add_to_swap_cache(page, entry);
1da177e4 170 radix_tree_preload_end();
fa1de900 171 }
1da177e4
LT
172 return error;
173}
174
1da177e4
LT
175/*
176 * This must be called only on pages that have
177 * been verified to be in the swap cache.
178 */
179void __delete_from_swap_cache(struct page *page)
180{
33806f06 181 struct address_space *address_space;
38d8b4e6
HY
182 int i, nr = hpage_nr_pages(page);
183 swp_entry_t entry;
184 pgoff_t idx;
33806f06 185
309381fe
SL
186 VM_BUG_ON_PAGE(!PageLocked(page), page);
187 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
188 VM_BUG_ON_PAGE(PageWriteback(page), page);
1da177e4 189
33806f06
SL
190 entry.val = page_private(page);
191 address_space = swap_address_space(entry);
38d8b4e6
HY
192 idx = swp_offset(entry);
193 for (i = 0; i < nr; i++) {
194 radix_tree_delete(&address_space->page_tree, idx + i);
195 set_page_private(page + i, 0);
196 }
1da177e4 197 ClearPageSwapCache(page);
38d8b4e6
HY
198 address_space->nrpages -= nr;
199 __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr);
200 ADD_CACHE_INFO(del_total, nr);
1da177e4
LT
201}
202
203/**
204 * add_to_swap - allocate swap space for a page
205 * @page: page we want to move to swap
206 *
207 * Allocate swap space for the page and add the page to the
208 * swap cache. Caller needs to hold the page lock.
209 */
0f074658 210int add_to_swap(struct page *page)
1da177e4
LT
211{
212 swp_entry_t entry;
1da177e4
LT
213 int err;
214
309381fe
SL
215 VM_BUG_ON_PAGE(!PageLocked(page), page);
216 VM_BUG_ON_PAGE(!PageUptodate(page), page);
1da177e4 217
38d8b4e6 218 entry = get_swap_page(page);
2ca4532a 219 if (!entry.val)
0f074658
MK
220 return 0;
221
38d8b4e6 222 if (mem_cgroup_try_charge_swap(page, entry))
0f074658 223 goto fail;
3f04f62f 224
2ca4532a
DN
225 /*
226 * Radix-tree node allocations from PF_MEMALLOC contexts could
227 * completely exhaust the page allocator. __GFP_NOMEMALLOC
228 * stops emergency reserves from being allocated.
229 *
230 * TODO: this could cause a theoretical memory reclaim
231 * deadlock in the swap out path.
232 */
233 /*
854e9ed0 234 * Add it to the swap cache.
2ca4532a
DN
235 */
236 err = add_to_swap_cache(page, entry,
237 __GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
38d8b4e6
HY
238 /* -ENOMEM radix-tree allocation failure */
239 if (err)
bd53b714 240 /*
2ca4532a
DN
241 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
242 * clear SWAP_HAS_CACHE flag.
1da177e4 243 */
0f074658 244 goto fail;
38d8b4e6
HY
245
246 return 1;
247
38d8b4e6 248fail:
0f074658 249 put_swap_page(page, entry);
38d8b4e6 250 return 0;
1da177e4
LT
251}
252
253/*
254 * This must be called only on pages that have
255 * been verified to be in the swap cache and locked.
256 * It will never put the page into the free list,
257 * the caller has a reference on the page.
258 */
259void delete_from_swap_cache(struct page *page)
260{
261 swp_entry_t entry;
33806f06 262 struct address_space *address_space;
1da177e4 263
4c21e2f2 264 entry.val = page_private(page);
1da177e4 265
33806f06
SL
266 address_space = swap_address_space(entry);
267 spin_lock_irq(&address_space->tree_lock);
1da177e4 268 __delete_from_swap_cache(page);
33806f06 269 spin_unlock_irq(&address_space->tree_lock);
1da177e4 270
75f6d6d2 271 put_swap_page(page, entry);
38d8b4e6 272 page_ref_sub(page, hpage_nr_pages(page));
1da177e4
LT
273}
274
1da177e4
LT
275/*
276 * If we are the only user, then try to free up the swap cache.
277 *
278 * Its ok to check for PageSwapCache without the page lock
a2c43eed
HD
279 * here because we are going to recheck again inside
280 * try_to_free_swap() _with_ the lock.
1da177e4
LT
281 * - Marcelo
282 */
283static inline void free_swap_cache(struct page *page)
284{
a2c43eed
HD
285 if (PageSwapCache(page) && !page_mapped(page) && trylock_page(page)) {
286 try_to_free_swap(page);
1da177e4
LT
287 unlock_page(page);
288 }
289}
290
291/*
292 * Perform a free_page(), also freeing any swap cache associated with
b8072f09 293 * this page if it is the last user of the page.
1da177e4
LT
294 */
295void free_page_and_swap_cache(struct page *page)
296{
297 free_swap_cache(page);
6fcb52a5 298 if (!is_huge_zero_page(page))
770a5370 299 put_page(page);
1da177e4
LT
300}
301
302/*
303 * Passed an array of pages, drop them all from swapcache and then release
304 * them. They are removed from the LRU and freed if this is their last use.
305 */
306void free_pages_and_swap_cache(struct page **pages, int nr)
307{
1da177e4 308 struct page **pagep = pages;
aabfb572 309 int i;
1da177e4
LT
310
311 lru_add_drain();
aabfb572
MH
312 for (i = 0; i < nr; i++)
313 free_swap_cache(pagep[i]);
314 release_pages(pagep, nr, false);
1da177e4
LT
315}
316
317/*
318 * Lookup a swap entry in the swap cache. A found page will be returned
319 * unlocked and with its refcount incremented - we rely on the kernel
320 * lock getting page table operations atomic even if we drop the page
321 * lock before returning.
322 */
ec560175
HY
323struct page *lookup_swap_cache(swp_entry_t entry, struct vm_area_struct *vma,
324 unsigned long addr)
1da177e4
LT
325{
326 struct page *page;
ec560175
HY
327 unsigned long ra_info;
328 int win, hits, readahead;
1da177e4 329
f6ab1f7f 330 page = find_get_page(swap_address_space(entry), swp_offset(entry));
1da177e4 331
ec560175
HY
332 INC_CACHE_INFO(find_total);
333 if (page) {
1da177e4 334 INC_CACHE_INFO(find_success);
ec560175
HY
335 if (unlikely(PageTransCompound(page)))
336 return page;
337 readahead = TestClearPageReadahead(page);
338 if (vma) {
339 ra_info = GET_SWAP_RA_VAL(vma);
340 win = SWAP_RA_WIN(ra_info);
341 hits = SWAP_RA_HITS(ra_info);
342 if (readahead)
343 hits = min_t(int, hits + 1, SWAP_RA_HITS_MAX);
344 atomic_long_set(&vma->swap_readahead_info,
345 SWAP_RA_VAL(addr, win, hits));
346 }
347 if (readahead) {
cbc65df2 348 count_vm_event(SWAP_RA_HIT);
ec560175
HY
349 if (!vma)
350 atomic_inc(&swapin_readahead_hits);
cbc65df2 351 }
579f8290 352 }
1da177e4
LT
353 return page;
354}
355
5b999aad
DS
356struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
357 struct vm_area_struct *vma, unsigned long addr,
358 bool *new_page_allocated)
1da177e4
LT
359{
360 struct page *found_page, *new_page = NULL;
5b999aad 361 struct address_space *swapper_space = swap_address_space(entry);
1da177e4 362 int err;
5b999aad 363 *new_page_allocated = false;
1da177e4
LT
364
365 do {
366 /*
367 * First check the swap cache. Since this is normally
368 * called after lookup_swap_cache() failed, re-calling
369 * that would confuse statistics.
370 */
f6ab1f7f 371 found_page = find_get_page(swapper_space, swp_offset(entry));
1da177e4
LT
372 if (found_page)
373 break;
374
ba81f838
HY
375 /*
376 * Just skip read ahead for unused swap slot.
377 * During swap_off when swap_slot_cache is disabled,
378 * we have to handle the race between putting
379 * swap entry in swap cache and marking swap slot
380 * as SWAP_HAS_CACHE. That's done in later part of code or
381 * else swap_off will be aborted if we return NULL.
382 */
383 if (!__swp_swapcount(entry) && swap_slot_cache_enabled)
384 break;
e8c26ab6 385
1da177e4
LT
386 /*
387 * Get a new page to read into from swap.
388 */
389 if (!new_page) {
02098fea 390 new_page = alloc_page_vma(gfp_mask, vma, addr);
1da177e4
LT
391 if (!new_page)
392 break; /* Out of memory */
393 }
394
31a56396
DN
395 /*
396 * call radix_tree_preload() while we can wait.
397 */
5e4c0d97 398 err = radix_tree_maybe_preload(gfp_mask & GFP_KERNEL);
31a56396
DN
399 if (err)
400 break;
401
f000944d
HD
402 /*
403 * Swap entry may have been freed since our caller observed it.
404 */
355cfa73 405 err = swapcache_prepare(entry);
cbab0e4e 406 if (err == -EEXIST) {
31a56396 407 radix_tree_preload_end();
cbab0e4e
RA
408 /*
409 * We might race against get_swap_page() and stumble
410 * across a SWAP_HAS_CACHE swap_map entry whose page
9c1cc2e4 411 * has not been brought into the swapcache yet.
cbab0e4e
RA
412 */
413 cond_resched();
355cfa73 414 continue;
31a56396
DN
415 }
416 if (err) { /* swp entry is obsolete ? */
417 radix_tree_preload_end();
f000944d 418 break;
31a56396 419 }
f000944d 420
2ca4532a 421 /* May fail (-ENOMEM) if radix-tree node allocation failed. */
48c935ad 422 __SetPageLocked(new_page);
fa9949da 423 __SetPageSwapBacked(new_page);
31a56396 424 err = __add_to_swap_cache(new_page, entry);
529ae9aa 425 if (likely(!err)) {
31a56396 426 radix_tree_preload_end();
1da177e4
LT
427 /*
428 * Initiate read into locked page and return.
429 */
c5fdae46 430 lru_cache_add_anon(new_page);
5b999aad 431 *new_page_allocated = true;
1da177e4
LT
432 return new_page;
433 }
31a56396 434 radix_tree_preload_end();
48c935ad 435 __ClearPageLocked(new_page);
2ca4532a
DN
436 /*
437 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
438 * clear SWAP_HAS_CACHE flag.
439 */
75f6d6d2 440 put_swap_page(new_page, entry);
f000944d 441 } while (err != -ENOMEM);
1da177e4
LT
442
443 if (new_page)
09cbfeaf 444 put_page(new_page);
1da177e4
LT
445 return found_page;
446}
46017e95 447
5b999aad
DS
448/*
449 * Locate a page of swap in physical memory, reserving swap cache space
450 * and reading the disk if it is not already cached.
451 * A failure return means that either the page allocation failed or that
452 * the swap entry is no longer in use.
453 */
454struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
23955622 455 struct vm_area_struct *vma, unsigned long addr, bool do_poll)
5b999aad
DS
456{
457 bool page_was_allocated;
458 struct page *retpage = __read_swap_cache_async(entry, gfp_mask,
459 vma, addr, &page_was_allocated);
460
461 if (page_was_allocated)
23955622 462 swap_readpage(retpage, do_poll);
5b999aad
DS
463
464 return retpage;
465}
466
ec560175
HY
467static unsigned int __swapin_nr_pages(unsigned long prev_offset,
468 unsigned long offset,
469 int hits,
470 int max_pages,
471 int prev_win)
579f8290 472{
ec560175 473 unsigned int pages, last_ra;
579f8290
SL
474
475 /*
476 * This heuristic has been found to work well on both sequential and
477 * random loads, swapping to hard disk or to SSD: please don't ask
478 * what the "+ 2" means, it just happens to work well, that's all.
479 */
ec560175 480 pages = hits + 2;
579f8290
SL
481 if (pages == 2) {
482 /*
483 * We can have no readahead hits to judge by: but must not get
484 * stuck here forever, so check for an adjacent offset instead
485 * (and don't even bother to check whether swap type is same).
486 */
487 if (offset != prev_offset + 1 && offset != prev_offset - 1)
488 pages = 1;
579f8290
SL
489 } else {
490 unsigned int roundup = 4;
491 while (roundup < pages)
492 roundup <<= 1;
493 pages = roundup;
494 }
495
496 if (pages > max_pages)
497 pages = max_pages;
498
499 /* Don't shrink readahead too fast */
ec560175 500 last_ra = prev_win / 2;
579f8290
SL
501 if (pages < last_ra)
502 pages = last_ra;
ec560175
HY
503
504 return pages;
505}
506
507static unsigned long swapin_nr_pages(unsigned long offset)
508{
509 static unsigned long prev_offset;
510 unsigned int hits, pages, max_pages;
511 static atomic_t last_readahead_pages;
512
513 max_pages = 1 << READ_ONCE(page_cluster);
514 if (max_pages <= 1)
515 return 1;
516
517 hits = atomic_xchg(&swapin_readahead_hits, 0);
518 pages = __swapin_nr_pages(prev_offset, offset, hits, max_pages,
519 atomic_read(&last_readahead_pages));
520 if (!hits)
521 prev_offset = offset;
579f8290
SL
522 atomic_set(&last_readahead_pages, pages);
523
524 return pages;
525}
526
46017e95
HD
527/**
528 * swapin_readahead - swap in pages in hope we need them soon
529 * @entry: swap entry of this memory
7682486b 530 * @gfp_mask: memory allocation flags
46017e95
HD
531 * @vma: user vma this address belongs to
532 * @addr: target address for mempolicy
533 *
534 * Returns the struct page for entry and addr, after queueing swapin.
535 *
536 * Primitive swap readahead code. We simply read an aligned block of
537 * (1 << page_cluster) entries in the swap area. This method is chosen
538 * because it doesn't cost us any seek time. We also make sure to queue
539 * the 'original' request together with the readahead ones...
540 *
541 * This has been extended to use the NUMA policies from the mm triggering
542 * the readahead.
543 *
544 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
545 */
02098fea 546struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
46017e95
HD
547 struct vm_area_struct *vma, unsigned long addr)
548{
46017e95 549 struct page *page;
579f8290
SL
550 unsigned long entry_offset = swp_offset(entry);
551 unsigned long offset = entry_offset;
67f96aa2 552 unsigned long start_offset, end_offset;
579f8290 553 unsigned long mask;
3fb5c298 554 struct blk_plug plug;
c4fa6309 555 bool do_poll = true, page_allocated;
46017e95 556
579f8290
SL
557 mask = swapin_nr_pages(offset) - 1;
558 if (!mask)
559 goto skip;
560
23955622 561 do_poll = false;
67f96aa2
RR
562 /* Read a page_cluster sized and aligned cluster around offset. */
563 start_offset = offset & ~mask;
564 end_offset = offset | mask;
565 if (!start_offset) /* First page is swap header. */
566 start_offset++;
567
3fb5c298 568 blk_start_plug(&plug);
67f96aa2 569 for (offset = start_offset; offset <= end_offset ; offset++) {
46017e95 570 /* Ok, do the async read-ahead now */
c4fa6309
HY
571 page = __read_swap_cache_async(
572 swp_entry(swp_type(entry), offset),
573 gfp_mask, vma, addr, &page_allocated);
46017e95 574 if (!page)
67f96aa2 575 continue;
c4fa6309
HY
576 if (page_allocated) {
577 swap_readpage(page, false);
578 if (offset != entry_offset &&
579 likely(!PageTransCompound(page))) {
580 SetPageReadahead(page);
581 count_vm_event(SWAP_RA);
582 }
cbc65df2 583 }
09cbfeaf 584 put_page(page);
46017e95 585 }
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586 blk_finish_plug(&plug);
587
46017e95 588 lru_add_drain(); /* Push any new pages onto the LRU now */
579f8290 589skip:
23955622 590 return read_swap_cache_async(entry, gfp_mask, vma, addr, do_poll);
46017e95 591}
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592
593int init_swap_address_space(unsigned int type, unsigned long nr_pages)
594{
595 struct address_space *spaces, *space;
596 unsigned int i, nr;
597
598 nr = DIV_ROUND_UP(nr_pages, SWAP_ADDRESS_SPACE_PAGES);
54f180d3 599 spaces = kvzalloc(sizeof(struct address_space) * nr, GFP_KERNEL);
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HY
600 if (!spaces)
601 return -ENOMEM;
602 for (i = 0; i < nr; i++) {
603 space = spaces + i;
604 INIT_RADIX_TREE(&space->page_tree, GFP_ATOMIC|__GFP_NOWARN);
605 atomic_set(&space->i_mmap_writable, 0);
606 space->a_ops = &swap_aops;
607 /* swap cache doesn't use writeback related tags */
608 mapping_set_no_writeback_tags(space);
609 spin_lock_init(&space->tree_lock);
610 }
611 nr_swapper_spaces[type] = nr;
612 rcu_assign_pointer(swapper_spaces[type], spaces);
613
614 return 0;
615}
616
617void exit_swap_address_space(unsigned int type)
618{
619 struct address_space *spaces;
620
621 spaces = swapper_spaces[type];
622 nr_swapper_spaces[type] = 0;
623 rcu_assign_pointer(swapper_spaces[type], NULL);
624 synchronize_rcu();
625 kvfree(spaces);
626}
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627
628static inline void swap_ra_clamp_pfn(struct vm_area_struct *vma,
629 unsigned long faddr,
630 unsigned long lpfn,
631 unsigned long rpfn,
632 unsigned long *start,
633 unsigned long *end)
634{
635 *start = max3(lpfn, PFN_DOWN(vma->vm_start),
636 PFN_DOWN(faddr & PMD_MASK));
637 *end = min3(rpfn, PFN_DOWN(vma->vm_end),
638 PFN_DOWN((faddr & PMD_MASK) + PMD_SIZE));
639}
640
641struct page *swap_readahead_detect(struct vm_fault *vmf,
642 struct vma_swap_readahead *swap_ra)
643{
644 struct vm_area_struct *vma = vmf->vma;
645 unsigned long swap_ra_info;
646 struct page *page;
647 swp_entry_t entry;
648 unsigned long faddr, pfn, fpfn;
649 unsigned long start, end;
650 pte_t *pte;
651 unsigned int max_win, hits, prev_win, win, left;
652#ifndef CONFIG_64BIT
653 pte_t *tpte;
654#endif
655
656 faddr = vmf->address;
657 entry = pte_to_swp_entry(vmf->orig_pte);
658 if ((unlikely(non_swap_entry(entry))))
659 return NULL;
660 page = lookup_swap_cache(entry, vma, faddr);
661 if (page)
662 return page;
663
664 max_win = 1 << READ_ONCE(swap_ra_max_order);
665 if (max_win == 1) {
666 swap_ra->win = 1;
667 return NULL;
668 }
669
670 fpfn = PFN_DOWN(faddr);
671 swap_ra_info = GET_SWAP_RA_VAL(vma);
672 pfn = PFN_DOWN(SWAP_RA_ADDR(swap_ra_info));
673 prev_win = SWAP_RA_WIN(swap_ra_info);
674 hits = SWAP_RA_HITS(swap_ra_info);
675 swap_ra->win = win = __swapin_nr_pages(pfn, fpfn, hits,
676 max_win, prev_win);
677 atomic_long_set(&vma->swap_readahead_info,
678 SWAP_RA_VAL(faddr, win, 0));
679
680 if (win == 1)
681 return NULL;
682
683 /* Copy the PTEs because the page table may be unmapped */
684 if (fpfn == pfn + 1)
685 swap_ra_clamp_pfn(vma, faddr, fpfn, fpfn + win, &start, &end);
686 else if (pfn == fpfn + 1)
687 swap_ra_clamp_pfn(vma, faddr, fpfn - win + 1, fpfn + 1,
688 &start, &end);
689 else {
690 left = (win - 1) / 2;
691 swap_ra_clamp_pfn(vma, faddr, fpfn - left, fpfn + win - left,
692 &start, &end);
693 }
694 swap_ra->nr_pte = end - start;
695 swap_ra->offset = fpfn - start;
696 pte = vmf->pte - swap_ra->offset;
697#ifdef CONFIG_64BIT
698 swap_ra->ptes = pte;
699#else
700 tpte = swap_ra->ptes;
701 for (pfn = start; pfn != end; pfn++)
702 *tpte++ = *pte++;
703#endif
704
705 return NULL;
706}
707
708struct page *do_swap_page_readahead(swp_entry_t fentry, gfp_t gfp_mask,
709 struct vm_fault *vmf,
710 struct vma_swap_readahead *swap_ra)
711{
712 struct blk_plug plug;
713 struct vm_area_struct *vma = vmf->vma;
714 struct page *page;
715 pte_t *pte, pentry;
716 swp_entry_t entry;
717 unsigned int i;
718 bool page_allocated;
719
720 if (swap_ra->win == 1)
721 goto skip;
722
723 blk_start_plug(&plug);
724 for (i = 0, pte = swap_ra->ptes; i < swap_ra->nr_pte;
725 i++, pte++) {
726 pentry = *pte;
727 if (pte_none(pentry))
728 continue;
729 if (pte_present(pentry))
730 continue;
731 entry = pte_to_swp_entry(pentry);
732 if (unlikely(non_swap_entry(entry)))
733 continue;
734 page = __read_swap_cache_async(entry, gfp_mask, vma,
735 vmf->address, &page_allocated);
736 if (!page)
737 continue;
738 if (page_allocated) {
739 swap_readpage(page, false);
740 if (i != swap_ra->offset &&
741 likely(!PageTransCompound(page))) {
742 SetPageReadahead(page);
743 count_vm_event(SWAP_RA);
744 }
745 }
746 put_page(page);
747 }
748 blk_finish_plug(&plug);
749 lru_add_drain();
750skip:
751 return read_swap_cache_async(fentry, gfp_mask, vma, vmf->address,
752 swap_ra->win == 1);
753}
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754
755#ifdef CONFIG_SYSFS
756static ssize_t vma_ra_enabled_show(struct kobject *kobj,
757 struct kobj_attribute *attr, char *buf)
758{
759 return sprintf(buf, "%s\n", swap_vma_readahead ? "true" : "false");
760}
761static ssize_t vma_ra_enabled_store(struct kobject *kobj,
762 struct kobj_attribute *attr,
763 const char *buf, size_t count)
764{
765 if (!strncmp(buf, "true", 4) || !strncmp(buf, "1", 1))
766 swap_vma_readahead = true;
767 else if (!strncmp(buf, "false", 5) || !strncmp(buf, "0", 1))
768 swap_vma_readahead = false;
769 else
770 return -EINVAL;
771
772 return count;
773}
774static struct kobj_attribute vma_ra_enabled_attr =
775 __ATTR(vma_ra_enabled, 0644, vma_ra_enabled_show,
776 vma_ra_enabled_store);
777
778static ssize_t vma_ra_max_order_show(struct kobject *kobj,
779 struct kobj_attribute *attr, char *buf)
780{
781 return sprintf(buf, "%d\n", swap_ra_max_order);
782}
783static ssize_t vma_ra_max_order_store(struct kobject *kobj,
784 struct kobj_attribute *attr,
785 const char *buf, size_t count)
786{
787 int err, v;
788
789 err = kstrtoint(buf, 10, &v);
790 if (err || v > SWAP_RA_ORDER_CEILING || v <= 0)
791 return -EINVAL;
792
793 swap_ra_max_order = v;
794
795 return count;
796}
797static struct kobj_attribute vma_ra_max_order_attr =
798 __ATTR(vma_ra_max_order, 0644, vma_ra_max_order_show,
799 vma_ra_max_order_store);
800
801static struct attribute *swap_attrs[] = {
802 &vma_ra_enabled_attr.attr,
803 &vma_ra_max_order_attr.attr,
804 NULL,
805};
806
807static struct attribute_group swap_attr_group = {
808 .attrs = swap_attrs,
809};
810
811static int __init swap_init_sysfs(void)
812{
813 int err;
814 struct kobject *swap_kobj;
815
816 swap_kobj = kobject_create_and_add("swap", mm_kobj);
817 if (!swap_kobj) {
818 pr_err("failed to create swap kobject\n");
819 return -ENOMEM;
820 }
821 err = sysfs_create_group(swap_kobj, &swap_attr_group);
822 if (err) {
823 pr_err("failed to register swap group\n");
824 goto delete_obj;
825 }
826 return 0;
827
828delete_obj:
829 kobject_put(swap_kobj);
830 return err;
831}
832subsys_initcall(swap_init_sysfs);
833#endif