1 // SPDX-License-Identifier: GPL-2.0-only
5 * Author: Vitaly Wool <vitaly.wool@konsulko.com>
6 * Copyright (C) 2016, Sony Mobile Communications Inc.
8 * This implementation is based on zbud written by Seth Jennings.
10 * z3fold is an special purpose allocator for storing compressed pages. It
11 * can store up to three compressed pages per page which improves the
12 * compression ratio of zbud while retaining its main concepts (e. g. always
13 * storing an integral number of objects per page) and simplicity.
14 * It still has simple and deterministic reclaim properties that make it
15 * preferable to a higher density approach (with no requirement on integral
16 * number of object per page) when reclaim is used.
18 * As in zbud, pages are divided into "chunks". The size of the chunks is
19 * fixed at compile time and is determined by NCHUNKS_ORDER below.
21 * z3fold doesn't export any API and is meant to be used via zpool API.
24 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26 #include <linux/atomic.h>
27 #include <linux/sched.h>
28 #include <linux/cpumask.h>
29 #include <linux/list.h>
31 #include <linux/module.h>
32 #include <linux/page-flags.h>
33 #include <linux/migrate.h>
34 #include <linux/node.h>
35 #include <linux/compaction.h>
36 #include <linux/percpu.h>
37 #include <linux/mount.h>
38 #include <linux/pseudo_fs.h>
40 #include <linux/preempt.h>
41 #include <linux/workqueue.h>
42 #include <linux/slab.h>
43 #include <linux/spinlock.h>
44 #include <linux/zpool.h>
45 #include <linux/magic.h>
46 #include <linux/kmemleak.h>
49 * NCHUNKS_ORDER determines the internal allocation granularity, effectively
50 * adjusting internal fragmentation. It also determines the number of
51 * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
52 * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
53 * in the beginning of an allocated page are occupied by z3fold header, so
54 * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
55 * which shows the max number of free chunks in z3fold page, also there will
56 * be 63, or 62, respectively, freelists per pool.
58 #define NCHUNKS_ORDER 6
60 #define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
61 #define CHUNK_SIZE (1 << CHUNK_SHIFT)
62 #define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
63 #define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
64 #define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
65 #define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
67 #define BUDDY_MASK (0x3)
69 #define SLOTS_ALIGN (0x40)
76 int (*evict
)(struct z3fold_pool
*pool
, unsigned long handle
);
87 struct z3fold_buddy_slots
{
89 * we are using BUDDY_MASK in handle_to_buddy etc. so there should
90 * be enough slots to hold all possible variants
92 unsigned long slot
[BUDDY_MASK
+ 1];
93 unsigned long pool
; /* back link */
96 #define HANDLE_FLAG_MASK (0x03)
99 * struct z3fold_header - z3fold page metadata occupying first chunks of each
100 * z3fold page, except for HEADLESS pages
101 * @buddy: links the z3fold page into the relevant list in the
103 * @page_lock: per-page lock
104 * @refcount: reference count for the z3fold page
105 * @work: work_struct for page layout optimization
106 * @slots: pointer to the structure holding buddy slots
107 * @pool: pointer to the containing pool
108 * @cpu: CPU which this page "belongs" to
109 * @first_chunks: the size of the first buddy in chunks, 0 if free
110 * @middle_chunks: the size of the middle buddy in chunks, 0 if free
111 * @last_chunks: the size of the last buddy in chunks, 0 if free
112 * @first_num: the starting number (for the first handle)
113 * @mapped_count: the number of objects currently mapped
115 struct z3fold_header
{
116 struct list_head buddy
;
117 spinlock_t page_lock
;
118 struct kref refcount
;
119 struct work_struct work
;
120 struct z3fold_buddy_slots
*slots
;
121 struct z3fold_pool
*pool
;
123 unsigned short first_chunks
;
124 unsigned short middle_chunks
;
125 unsigned short last_chunks
;
126 unsigned short start_middle
;
127 unsigned short first_num
:2;
128 unsigned short mapped_count
:2;
129 unsigned short foreign_handles
:2;
133 * struct z3fold_pool - stores metadata for each z3fold pool
135 * @lock: protects pool unbuddied/lru lists
136 * @stale_lock: protects pool stale page list
137 * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
138 * buddies; the list each z3fold page is added to depends on
139 * the size of its free region.
140 * @lru: list tracking the z3fold pages in LRU order by most recently
142 * @stale: list of pages marked for freeing
143 * @pages_nr: number of z3fold pages in the pool.
144 * @c_handle: cache for z3fold_buddy_slots allocation
145 * @ops: pointer to a structure of user defined operations specified at
146 * pool creation time.
147 * @compact_wq: workqueue for page layout background optimization
148 * @release_wq: workqueue for safe page release
149 * @work: work_struct for safe page release
150 * @inode: inode for z3fold pseudo filesystem
152 * This structure is allocated at pool creation time and maintains metadata
153 * pertaining to a particular z3fold pool.
158 spinlock_t stale_lock
;
159 struct list_head
*unbuddied
;
160 struct list_head lru
;
161 struct list_head stale
;
163 struct kmem_cache
*c_handle
;
164 const struct z3fold_ops
*ops
;
166 const struct zpool_ops
*zpool_ops
;
167 struct workqueue_struct
*compact_wq
;
168 struct workqueue_struct
*release_wq
;
169 struct work_struct work
;
174 * Internal z3fold page flags
176 enum z3fold_page_flags
{
181 PAGE_CLAIMED
, /* by either reclaim or free */
185 * handle flags, go under HANDLE_FLAG_MASK
187 enum z3fold_handle_flags
{
192 * Forward declarations
194 static struct z3fold_header
*__z3fold_alloc(struct z3fold_pool
*, size_t, bool);
195 static void compact_page_work(struct work_struct
*w
);
201 /* Converts an allocation size in bytes to size in z3fold chunks */
202 static int size_to_chunks(size_t size
)
204 return (size
+ CHUNK_SIZE
- 1) >> CHUNK_SHIFT
;
207 #define for_each_unbuddied_list(_iter, _begin) \
208 for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
210 static inline struct z3fold_buddy_slots
*alloc_slots(struct z3fold_pool
*pool
,
213 struct z3fold_buddy_slots
*slots
;
215 slots
= kmem_cache_zalloc(pool
->c_handle
,
216 (gfp
& ~(__GFP_HIGHMEM
| __GFP_MOVABLE
)));
219 /* It will be freed separately in free_handle(). */
220 kmemleak_not_leak(slots
);
221 slots
->pool
= (unsigned long)pool
;
222 rwlock_init(&slots
->lock
);
228 static inline struct z3fold_pool
*slots_to_pool(struct z3fold_buddy_slots
*s
)
230 return (struct z3fold_pool
*)(s
->pool
& ~HANDLE_FLAG_MASK
);
233 static inline struct z3fold_buddy_slots
*handle_to_slots(unsigned long handle
)
235 return (struct z3fold_buddy_slots
*)(handle
& ~(SLOTS_ALIGN
- 1));
238 /* Lock a z3fold page */
239 static inline void z3fold_page_lock(struct z3fold_header
*zhdr
)
241 spin_lock(&zhdr
->page_lock
);
244 /* Try to lock a z3fold page */
245 static inline int z3fold_page_trylock(struct z3fold_header
*zhdr
)
247 return spin_trylock(&zhdr
->page_lock
);
250 /* Unlock a z3fold page */
251 static inline void z3fold_page_unlock(struct z3fold_header
*zhdr
)
253 spin_unlock(&zhdr
->page_lock
);
257 static inline struct z3fold_header
*__get_z3fold_header(unsigned long handle
,
260 struct z3fold_buddy_slots
*slots
;
261 struct z3fold_header
*zhdr
;
264 if (!(handle
& (1 << PAGE_HEADLESS
))) {
265 slots
= handle_to_slots(handle
);
269 read_lock(&slots
->lock
);
270 addr
= *(unsigned long *)handle
;
271 zhdr
= (struct z3fold_header
*)(addr
& PAGE_MASK
);
273 locked
= z3fold_page_trylock(zhdr
);
274 read_unlock(&slots
->lock
);
280 zhdr
= (struct z3fold_header
*)(handle
& PAGE_MASK
);
286 /* Returns the z3fold page where a given handle is stored */
287 static inline struct z3fold_header
*handle_to_z3fold_header(unsigned long h
)
289 return __get_z3fold_header(h
, false);
292 /* return locked z3fold page if it's not headless */
293 static inline struct z3fold_header
*get_z3fold_header(unsigned long h
)
295 return __get_z3fold_header(h
, true);
298 static inline void put_z3fold_header(struct z3fold_header
*zhdr
)
300 struct page
*page
= virt_to_page(zhdr
);
302 if (!test_bit(PAGE_HEADLESS
, &page
->private))
303 z3fold_page_unlock(zhdr
);
306 static inline void free_handle(unsigned long handle
, struct z3fold_header
*zhdr
)
308 struct z3fold_buddy_slots
*slots
;
312 if (handle
& (1 << PAGE_HEADLESS
))
315 if (WARN_ON(*(unsigned long *)handle
== 0))
318 slots
= handle_to_slots(handle
);
319 write_lock(&slots
->lock
);
320 *(unsigned long *)handle
= 0;
322 if (test_bit(HANDLES_NOFREE
, &slots
->pool
)) {
323 write_unlock(&slots
->lock
);
324 return; /* simple case, nothing else to do */
327 if (zhdr
->slots
!= slots
)
328 zhdr
->foreign_handles
--;
331 for (i
= 0; i
<= BUDDY_MASK
; i
++) {
332 if (slots
->slot
[i
]) {
337 write_unlock(&slots
->lock
);
340 struct z3fold_pool
*pool
= slots_to_pool(slots
);
342 if (zhdr
->slots
== slots
)
344 kmem_cache_free(pool
->c_handle
, slots
);
348 static int z3fold_init_fs_context(struct fs_context
*fc
)
350 return init_pseudo(fc
, Z3FOLD_MAGIC
) ? 0 : -ENOMEM
;
353 static struct file_system_type z3fold_fs
= {
355 .init_fs_context
= z3fold_init_fs_context
,
356 .kill_sb
= kill_anon_super
,
359 static struct vfsmount
*z3fold_mnt
;
360 static int z3fold_mount(void)
364 z3fold_mnt
= kern_mount(&z3fold_fs
);
365 if (IS_ERR(z3fold_mnt
))
366 ret
= PTR_ERR(z3fold_mnt
);
371 static void z3fold_unmount(void)
373 kern_unmount(z3fold_mnt
);
376 static const struct address_space_operations z3fold_aops
;
377 static int z3fold_register_migration(struct z3fold_pool
*pool
)
379 pool
->inode
= alloc_anon_inode(z3fold_mnt
->mnt_sb
);
380 if (IS_ERR(pool
->inode
)) {
385 pool
->inode
->i_mapping
->private_data
= pool
;
386 pool
->inode
->i_mapping
->a_ops
= &z3fold_aops
;
390 static void z3fold_unregister_migration(struct z3fold_pool
*pool
)
396 /* Initializes the z3fold header of a newly allocated z3fold page */
397 static struct z3fold_header
*init_z3fold_page(struct page
*page
, bool headless
,
398 struct z3fold_pool
*pool
, gfp_t gfp
)
400 struct z3fold_header
*zhdr
= page_address(page
);
401 struct z3fold_buddy_slots
*slots
;
403 INIT_LIST_HEAD(&page
->lru
);
404 clear_bit(PAGE_HEADLESS
, &page
->private);
405 clear_bit(MIDDLE_CHUNK_MAPPED
, &page
->private);
406 clear_bit(NEEDS_COMPACTING
, &page
->private);
407 clear_bit(PAGE_STALE
, &page
->private);
408 clear_bit(PAGE_CLAIMED
, &page
->private);
412 slots
= alloc_slots(pool
, gfp
);
416 memset(zhdr
, 0, sizeof(*zhdr
));
417 spin_lock_init(&zhdr
->page_lock
);
418 kref_init(&zhdr
->refcount
);
422 INIT_LIST_HEAD(&zhdr
->buddy
);
423 INIT_WORK(&zhdr
->work
, compact_page_work
);
427 /* Resets the struct page fields and frees the page */
428 static void free_z3fold_page(struct page
*page
, bool headless
)
432 __ClearPageMovable(page
);
435 ClearPagePrivate(page
);
439 /* Helper function to build the index */
440 static inline int __idx(struct z3fold_header
*zhdr
, enum buddy bud
)
442 return (bud
+ zhdr
->first_num
) & BUDDY_MASK
;
446 * Encodes the handle of a particular buddy within a z3fold page
447 * Pool lock should be held as this function accesses first_num
449 static unsigned long __encode_handle(struct z3fold_header
*zhdr
,
450 struct z3fold_buddy_slots
*slots
,
453 unsigned long h
= (unsigned long)zhdr
;
457 * For a headless page, its handle is its pointer with the extra
458 * PAGE_HEADLESS bit set
461 return h
| (1 << PAGE_HEADLESS
);
463 /* otherwise, return pointer to encoded handle */
464 idx
= __idx(zhdr
, bud
);
467 h
|= (zhdr
->last_chunks
<< BUDDY_SHIFT
);
469 write_lock(&slots
->lock
);
470 slots
->slot
[idx
] = h
;
471 write_unlock(&slots
->lock
);
472 return (unsigned long)&slots
->slot
[idx
];
475 static unsigned long encode_handle(struct z3fold_header
*zhdr
, enum buddy bud
)
477 return __encode_handle(zhdr
, zhdr
->slots
, bud
);
480 /* only for LAST bud, returns zero otherwise */
481 static unsigned short handle_to_chunks(unsigned long handle
)
483 struct z3fold_buddy_slots
*slots
= handle_to_slots(handle
);
486 read_lock(&slots
->lock
);
487 addr
= *(unsigned long *)handle
;
488 read_unlock(&slots
->lock
);
489 return (addr
& ~PAGE_MASK
) >> BUDDY_SHIFT
;
493 * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
494 * but that doesn't matter. because the masking will result in the
495 * correct buddy number.
497 static enum buddy
handle_to_buddy(unsigned long handle
)
499 struct z3fold_header
*zhdr
;
500 struct z3fold_buddy_slots
*slots
= handle_to_slots(handle
);
503 read_lock(&slots
->lock
);
504 WARN_ON(handle
& (1 << PAGE_HEADLESS
));
505 addr
= *(unsigned long *)handle
;
506 read_unlock(&slots
->lock
);
507 zhdr
= (struct z3fold_header
*)(addr
& PAGE_MASK
);
508 return (addr
- zhdr
->first_num
) & BUDDY_MASK
;
511 static inline struct z3fold_pool
*zhdr_to_pool(struct z3fold_header
*zhdr
)
516 static void __release_z3fold_page(struct z3fold_header
*zhdr
, bool locked
)
518 struct page
*page
= virt_to_page(zhdr
);
519 struct z3fold_pool
*pool
= zhdr_to_pool(zhdr
);
521 WARN_ON(!list_empty(&zhdr
->buddy
));
522 set_bit(PAGE_STALE
, &page
->private);
523 clear_bit(NEEDS_COMPACTING
, &page
->private);
524 spin_lock(&pool
->lock
);
525 if (!list_empty(&page
->lru
))
526 list_del_init(&page
->lru
);
527 spin_unlock(&pool
->lock
);
530 z3fold_page_unlock(zhdr
);
532 spin_lock(&pool
->stale_lock
);
533 list_add(&zhdr
->buddy
, &pool
->stale
);
534 queue_work(pool
->release_wq
, &pool
->work
);
535 spin_unlock(&pool
->stale_lock
);
538 static void release_z3fold_page(struct kref
*ref
)
540 struct z3fold_header
*zhdr
= container_of(ref
, struct z3fold_header
,
542 __release_z3fold_page(zhdr
, false);
545 static void release_z3fold_page_locked(struct kref
*ref
)
547 struct z3fold_header
*zhdr
= container_of(ref
, struct z3fold_header
,
549 WARN_ON(z3fold_page_trylock(zhdr
));
550 __release_z3fold_page(zhdr
, true);
553 static void release_z3fold_page_locked_list(struct kref
*ref
)
555 struct z3fold_header
*zhdr
= container_of(ref
, struct z3fold_header
,
557 struct z3fold_pool
*pool
= zhdr_to_pool(zhdr
);
559 spin_lock(&pool
->lock
);
560 list_del_init(&zhdr
->buddy
);
561 spin_unlock(&pool
->lock
);
563 WARN_ON(z3fold_page_trylock(zhdr
));
564 __release_z3fold_page(zhdr
, true);
567 static void free_pages_work(struct work_struct
*w
)
569 struct z3fold_pool
*pool
= container_of(w
, struct z3fold_pool
, work
);
571 spin_lock(&pool
->stale_lock
);
572 while (!list_empty(&pool
->stale
)) {
573 struct z3fold_header
*zhdr
= list_first_entry(&pool
->stale
,
574 struct z3fold_header
, buddy
);
575 struct page
*page
= virt_to_page(zhdr
);
577 list_del(&zhdr
->buddy
);
578 if (WARN_ON(!test_bit(PAGE_STALE
, &page
->private)))
580 spin_unlock(&pool
->stale_lock
);
581 cancel_work_sync(&zhdr
->work
);
582 free_z3fold_page(page
, false);
584 spin_lock(&pool
->stale_lock
);
586 spin_unlock(&pool
->stale_lock
);
590 * Returns the number of free chunks in a z3fold page.
591 * NB: can't be used with HEADLESS pages.
593 static int num_free_chunks(struct z3fold_header
*zhdr
)
597 * If there is a middle object, pick up the bigger free space
598 * either before or after it. Otherwise just subtract the number
599 * of chunks occupied by the first and the last objects.
601 if (zhdr
->middle_chunks
!= 0) {
602 int nfree_before
= zhdr
->first_chunks
?
603 0 : zhdr
->start_middle
- ZHDR_CHUNKS
;
604 int nfree_after
= zhdr
->last_chunks
?
606 (zhdr
->start_middle
+ zhdr
->middle_chunks
);
607 nfree
= max(nfree_before
, nfree_after
);
609 nfree
= NCHUNKS
- zhdr
->first_chunks
- zhdr
->last_chunks
;
613 /* Add to the appropriate unbuddied list */
614 static inline void add_to_unbuddied(struct z3fold_pool
*pool
,
615 struct z3fold_header
*zhdr
)
617 if (zhdr
->first_chunks
== 0 || zhdr
->last_chunks
== 0 ||
618 zhdr
->middle_chunks
== 0) {
619 struct list_head
*unbuddied
;
620 int freechunks
= num_free_chunks(zhdr
);
623 unbuddied
= this_cpu_ptr(pool
->unbuddied
);
624 spin_lock(&pool
->lock
);
625 list_add(&zhdr
->buddy
, &unbuddied
[freechunks
]);
626 spin_unlock(&pool
->lock
);
627 zhdr
->cpu
= smp_processor_id();
632 static inline enum buddy
get_free_buddy(struct z3fold_header
*zhdr
, int chunks
)
634 enum buddy bud
= HEADLESS
;
636 if (zhdr
->middle_chunks
) {
637 if (!zhdr
->first_chunks
&&
638 chunks
<= zhdr
->start_middle
- ZHDR_CHUNKS
)
640 else if (!zhdr
->last_chunks
)
643 if (!zhdr
->first_chunks
)
645 else if (!zhdr
->last_chunks
)
654 static inline void *mchunk_memmove(struct z3fold_header
*zhdr
,
655 unsigned short dst_chunk
)
658 return memmove(beg
+ (dst_chunk
<< CHUNK_SHIFT
),
659 beg
+ (zhdr
->start_middle
<< CHUNK_SHIFT
),
660 zhdr
->middle_chunks
<< CHUNK_SHIFT
);
663 static inline bool buddy_single(struct z3fold_header
*zhdr
)
665 return !((zhdr
->first_chunks
&& zhdr
->middle_chunks
) ||
666 (zhdr
->first_chunks
&& zhdr
->last_chunks
) ||
667 (zhdr
->middle_chunks
&& zhdr
->last_chunks
));
670 static struct z3fold_header
*compact_single_buddy(struct z3fold_header
*zhdr
)
672 struct z3fold_pool
*pool
= zhdr_to_pool(zhdr
);
674 unsigned long old_handle
= 0;
676 struct z3fold_header
*new_zhdr
= NULL
;
677 int first_idx
= __idx(zhdr
, FIRST
);
678 int middle_idx
= __idx(zhdr
, MIDDLE
);
679 int last_idx
= __idx(zhdr
, LAST
);
680 unsigned short *moved_chunks
= NULL
;
683 * No need to protect slots here -- all the slots are "local" and
684 * the page lock is already taken
686 if (zhdr
->first_chunks
&& zhdr
->slots
->slot
[first_idx
]) {
687 p
+= ZHDR_SIZE_ALIGNED
;
688 sz
= zhdr
->first_chunks
<< CHUNK_SHIFT
;
689 old_handle
= (unsigned long)&zhdr
->slots
->slot
[first_idx
];
690 moved_chunks
= &zhdr
->first_chunks
;
691 } else if (zhdr
->middle_chunks
&& zhdr
->slots
->slot
[middle_idx
]) {
692 p
+= zhdr
->start_middle
<< CHUNK_SHIFT
;
693 sz
= zhdr
->middle_chunks
<< CHUNK_SHIFT
;
694 old_handle
= (unsigned long)&zhdr
->slots
->slot
[middle_idx
];
695 moved_chunks
= &zhdr
->middle_chunks
;
696 } else if (zhdr
->last_chunks
&& zhdr
->slots
->slot
[last_idx
]) {
697 p
+= PAGE_SIZE
- (zhdr
->last_chunks
<< CHUNK_SHIFT
);
698 sz
= zhdr
->last_chunks
<< CHUNK_SHIFT
;
699 old_handle
= (unsigned long)&zhdr
->slots
->slot
[last_idx
];
700 moved_chunks
= &zhdr
->last_chunks
;
704 enum buddy new_bud
= HEADLESS
;
705 short chunks
= size_to_chunks(sz
);
708 new_zhdr
= __z3fold_alloc(pool
, sz
, false);
712 if (WARN_ON(new_zhdr
== zhdr
))
715 new_bud
= get_free_buddy(new_zhdr
, chunks
);
719 new_zhdr
->first_chunks
= chunks
;
720 q
+= ZHDR_SIZE_ALIGNED
;
723 new_zhdr
->middle_chunks
= chunks
;
724 new_zhdr
->start_middle
=
725 new_zhdr
->first_chunks
+ ZHDR_CHUNKS
;
726 q
+= new_zhdr
->start_middle
<< CHUNK_SHIFT
;
729 new_zhdr
->last_chunks
= chunks
;
730 q
+= PAGE_SIZE
- (new_zhdr
->last_chunks
<< CHUNK_SHIFT
);
735 new_zhdr
->foreign_handles
++;
737 write_lock(&zhdr
->slots
->lock
);
738 *(unsigned long *)old_handle
= (unsigned long)new_zhdr
+
739 __idx(new_zhdr
, new_bud
);
741 *(unsigned long *)old_handle
|=
742 (new_zhdr
->last_chunks
<< BUDDY_SHIFT
);
743 write_unlock(&zhdr
->slots
->lock
);
744 add_to_unbuddied(pool
, new_zhdr
);
745 z3fold_page_unlock(new_zhdr
);
754 if (kref_put(&new_zhdr
->refcount
, release_z3fold_page_locked
))
755 atomic64_dec(&pool
->pages_nr
);
757 add_to_unbuddied(pool
, new_zhdr
);
758 z3fold_page_unlock(new_zhdr
);
765 #define BIG_CHUNK_GAP 3
766 /* Has to be called with lock held */
767 static int z3fold_compact_page(struct z3fold_header
*zhdr
)
769 struct page
*page
= virt_to_page(zhdr
);
771 if (test_bit(MIDDLE_CHUNK_MAPPED
, &page
->private))
772 return 0; /* can't move middle chunk, it's used */
774 if (unlikely(PageIsolated(page
)))
777 if (zhdr
->middle_chunks
== 0)
778 return 0; /* nothing to compact */
780 if (zhdr
->first_chunks
== 0 && zhdr
->last_chunks
== 0) {
781 /* move to the beginning */
782 mchunk_memmove(zhdr
, ZHDR_CHUNKS
);
783 zhdr
->first_chunks
= zhdr
->middle_chunks
;
784 zhdr
->middle_chunks
= 0;
785 zhdr
->start_middle
= 0;
791 * moving data is expensive, so let's only do that if
792 * there's substantial gain (at least BIG_CHUNK_GAP chunks)
794 if (zhdr
->first_chunks
!= 0 && zhdr
->last_chunks
== 0 &&
795 zhdr
->start_middle
- (zhdr
->first_chunks
+ ZHDR_CHUNKS
) >=
797 mchunk_memmove(zhdr
, zhdr
->first_chunks
+ ZHDR_CHUNKS
);
798 zhdr
->start_middle
= zhdr
->first_chunks
+ ZHDR_CHUNKS
;
800 } else if (zhdr
->last_chunks
!= 0 && zhdr
->first_chunks
== 0 &&
801 TOTAL_CHUNKS
- (zhdr
->last_chunks
+ zhdr
->start_middle
802 + zhdr
->middle_chunks
) >=
804 unsigned short new_start
= TOTAL_CHUNKS
- zhdr
->last_chunks
-
806 mchunk_memmove(zhdr
, new_start
);
807 zhdr
->start_middle
= new_start
;
814 static void do_compact_page(struct z3fold_header
*zhdr
, bool locked
)
816 struct z3fold_pool
*pool
= zhdr_to_pool(zhdr
);
819 page
= virt_to_page(zhdr
);
821 WARN_ON(z3fold_page_trylock(zhdr
));
823 z3fold_page_lock(zhdr
);
824 if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING
, &page
->private))) {
825 z3fold_page_unlock(zhdr
);
828 spin_lock(&pool
->lock
);
829 list_del_init(&zhdr
->buddy
);
830 spin_unlock(&pool
->lock
);
832 if (kref_put(&zhdr
->refcount
, release_z3fold_page_locked
)) {
833 atomic64_dec(&pool
->pages_nr
);
837 if (test_bit(PAGE_STALE
, &page
->private) ||
838 test_and_set_bit(PAGE_CLAIMED
, &page
->private)) {
839 z3fold_page_unlock(zhdr
);
843 if (!zhdr
->foreign_handles
&& buddy_single(zhdr
) &&
844 zhdr
->mapped_count
== 0 && compact_single_buddy(zhdr
)) {
845 if (kref_put(&zhdr
->refcount
, release_z3fold_page_locked
))
846 atomic64_dec(&pool
->pages_nr
);
848 clear_bit(PAGE_CLAIMED
, &page
->private);
849 z3fold_page_unlock(zhdr
);
854 z3fold_compact_page(zhdr
);
855 add_to_unbuddied(pool
, zhdr
);
856 clear_bit(PAGE_CLAIMED
, &page
->private);
857 z3fold_page_unlock(zhdr
);
860 static void compact_page_work(struct work_struct
*w
)
862 struct z3fold_header
*zhdr
= container_of(w
, struct z3fold_header
,
865 do_compact_page(zhdr
, false);
868 /* returns _locked_ z3fold page header or NULL */
869 static inline struct z3fold_header
*__z3fold_alloc(struct z3fold_pool
*pool
,
870 size_t size
, bool can_sleep
)
872 struct z3fold_header
*zhdr
= NULL
;
874 struct list_head
*unbuddied
;
875 int chunks
= size_to_chunks(size
), i
;
879 /* First, try to find an unbuddied z3fold page. */
880 unbuddied
= this_cpu_ptr(pool
->unbuddied
);
881 for_each_unbuddied_list(i
, chunks
) {
882 struct list_head
*l
= &unbuddied
[i
];
884 zhdr
= list_first_entry_or_null(READ_ONCE(l
),
885 struct z3fold_header
, buddy
);
890 /* Re-check under lock. */
891 spin_lock(&pool
->lock
);
893 if (unlikely(zhdr
!= list_first_entry(READ_ONCE(l
),
894 struct z3fold_header
, buddy
)) ||
895 !z3fold_page_trylock(zhdr
)) {
896 spin_unlock(&pool
->lock
);
903 list_del_init(&zhdr
->buddy
);
905 spin_unlock(&pool
->lock
);
907 page
= virt_to_page(zhdr
);
908 if (test_bit(NEEDS_COMPACTING
, &page
->private) ||
909 test_bit(PAGE_CLAIMED
, &page
->private)) {
910 z3fold_page_unlock(zhdr
);
919 * this page could not be removed from its unbuddied
920 * list while pool lock was held, and then we've taken
921 * page lock so kref_put could not be called before
922 * we got here, so it's safe to just call kref_get()
924 kref_get(&zhdr
->refcount
);
932 /* look for _exact_ match on other cpus' lists */
933 for_each_online_cpu(cpu
) {
936 unbuddied
= per_cpu_ptr(pool
->unbuddied
, cpu
);
937 spin_lock(&pool
->lock
);
938 l
= &unbuddied
[chunks
];
940 zhdr
= list_first_entry_or_null(READ_ONCE(l
),
941 struct z3fold_header
, buddy
);
943 if (!zhdr
|| !z3fold_page_trylock(zhdr
)) {
944 spin_unlock(&pool
->lock
);
948 list_del_init(&zhdr
->buddy
);
950 spin_unlock(&pool
->lock
);
952 page
= virt_to_page(zhdr
);
953 if (test_bit(NEEDS_COMPACTING
, &page
->private) ||
954 test_bit(PAGE_CLAIMED
, &page
->private)) {
955 z3fold_page_unlock(zhdr
);
961 kref_get(&zhdr
->refcount
);
966 if (zhdr
&& !zhdr
->slots
)
967 zhdr
->slots
= alloc_slots(pool
,
968 can_sleep
? GFP_NOIO
: GFP_ATOMIC
);
977 * z3fold_create_pool() - create a new z3fold pool
979 * @gfp: gfp flags when allocating the z3fold pool structure
980 * @ops: user-defined operations for the z3fold pool
982 * Return: pointer to the new z3fold pool or NULL if the metadata allocation
985 static struct z3fold_pool
*z3fold_create_pool(const char *name
, gfp_t gfp
,
986 const struct z3fold_ops
*ops
)
988 struct z3fold_pool
*pool
= NULL
;
991 pool
= kzalloc(sizeof(struct z3fold_pool
), gfp
);
994 pool
->c_handle
= kmem_cache_create("z3fold_handle",
995 sizeof(struct z3fold_buddy_slots
),
996 SLOTS_ALIGN
, 0, NULL
);
999 spin_lock_init(&pool
->lock
);
1000 spin_lock_init(&pool
->stale_lock
);
1001 pool
->unbuddied
= __alloc_percpu(sizeof(struct list_head
)*NCHUNKS
, 2);
1002 if (!pool
->unbuddied
)
1004 for_each_possible_cpu(cpu
) {
1005 struct list_head
*unbuddied
=
1006 per_cpu_ptr(pool
->unbuddied
, cpu
);
1007 for_each_unbuddied_list(i
, 0)
1008 INIT_LIST_HEAD(&unbuddied
[i
]);
1010 INIT_LIST_HEAD(&pool
->lru
);
1011 INIT_LIST_HEAD(&pool
->stale
);
1012 atomic64_set(&pool
->pages_nr
, 0);
1014 pool
->compact_wq
= create_singlethread_workqueue(pool
->name
);
1015 if (!pool
->compact_wq
)
1017 pool
->release_wq
= create_singlethread_workqueue(pool
->name
);
1018 if (!pool
->release_wq
)
1020 if (z3fold_register_migration(pool
))
1022 INIT_WORK(&pool
->work
, free_pages_work
);
1027 destroy_workqueue(pool
->release_wq
);
1029 destroy_workqueue(pool
->compact_wq
);
1031 free_percpu(pool
->unbuddied
);
1033 kmem_cache_destroy(pool
->c_handle
);
1041 * z3fold_destroy_pool() - destroys an existing z3fold pool
1042 * @pool: the z3fold pool to be destroyed
1044 * The pool should be emptied before this function is called.
1046 static void z3fold_destroy_pool(struct z3fold_pool
*pool
)
1048 kmem_cache_destroy(pool
->c_handle
);
1051 * We need to destroy pool->compact_wq before pool->release_wq,
1052 * as any pending work on pool->compact_wq will call
1053 * queue_work(pool->release_wq, &pool->work).
1055 * There are still outstanding pages until both workqueues are drained,
1056 * so we cannot unregister migration until then.
1059 destroy_workqueue(pool
->compact_wq
);
1060 destroy_workqueue(pool
->release_wq
);
1061 z3fold_unregister_migration(pool
);
1066 * z3fold_alloc() - allocates a region of a given size
1067 * @pool: z3fold pool from which to allocate
1068 * @size: size in bytes of the desired allocation
1069 * @gfp: gfp flags used if the pool needs to grow
1070 * @handle: handle of the new allocation
1072 * This function will attempt to find a free region in the pool large enough to
1073 * satisfy the allocation request. A search of the unbuddied lists is
1074 * performed first. If no suitable free region is found, then a new page is
1075 * allocated and added to the pool to satisfy the request.
1077 * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
1078 * as z3fold pool pages.
1080 * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
1081 * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
1084 static int z3fold_alloc(struct z3fold_pool
*pool
, size_t size
, gfp_t gfp
,
1085 unsigned long *handle
)
1087 int chunks
= size_to_chunks(size
);
1088 struct z3fold_header
*zhdr
= NULL
;
1089 struct page
*page
= NULL
;
1091 bool can_sleep
= gfpflags_allow_blocking(gfp
);
1096 if (size
> PAGE_SIZE
)
1099 if (size
> PAGE_SIZE
- ZHDR_SIZE_ALIGNED
- CHUNK_SIZE
)
1103 zhdr
= __z3fold_alloc(pool
, size
, can_sleep
);
1105 bud
= get_free_buddy(zhdr
, chunks
);
1106 if (bud
== HEADLESS
) {
1107 if (kref_put(&zhdr
->refcount
,
1108 release_z3fold_page_locked
))
1109 atomic64_dec(&pool
->pages_nr
);
1111 z3fold_page_unlock(zhdr
);
1112 pr_err("No free chunks in unbuddied\n");
1116 page
= virt_to_page(zhdr
);
1124 spin_lock(&pool
->stale_lock
);
1125 zhdr
= list_first_entry_or_null(&pool
->stale
,
1126 struct z3fold_header
, buddy
);
1128 * Before allocating a page, let's see if we can take one from
1129 * the stale pages list. cancel_work_sync() can sleep so we
1130 * limit this case to the contexts where we can sleep
1133 list_del(&zhdr
->buddy
);
1134 spin_unlock(&pool
->stale_lock
);
1135 cancel_work_sync(&zhdr
->work
);
1136 page
= virt_to_page(zhdr
);
1138 spin_unlock(&pool
->stale_lock
);
1142 page
= alloc_page(gfp
);
1147 zhdr
= init_z3fold_page(page
, bud
== HEADLESS
, pool
, gfp
);
1152 atomic64_inc(&pool
->pages_nr
);
1154 if (bud
== HEADLESS
) {
1155 set_bit(PAGE_HEADLESS
, &page
->private);
1160 __SetPageMovable(page
, pool
->inode
->i_mapping
);
1163 if (trylock_page(page
)) {
1164 __SetPageMovable(page
, pool
->inode
->i_mapping
);
1168 z3fold_page_lock(zhdr
);
1172 zhdr
->first_chunks
= chunks
;
1173 else if (bud
== LAST
)
1174 zhdr
->last_chunks
= chunks
;
1176 zhdr
->middle_chunks
= chunks
;
1177 zhdr
->start_middle
= zhdr
->first_chunks
+ ZHDR_CHUNKS
;
1179 add_to_unbuddied(pool
, zhdr
);
1182 spin_lock(&pool
->lock
);
1183 /* Add/move z3fold page to beginning of LRU */
1184 if (!list_empty(&page
->lru
))
1185 list_del(&page
->lru
);
1187 list_add(&page
->lru
, &pool
->lru
);
1189 *handle
= encode_handle(zhdr
, bud
);
1190 spin_unlock(&pool
->lock
);
1191 if (bud
!= HEADLESS
)
1192 z3fold_page_unlock(zhdr
);
1198 * z3fold_free() - frees the allocation associated with the given handle
1199 * @pool: pool in which the allocation resided
1200 * @handle: handle associated with the allocation returned by z3fold_alloc()
1202 * In the case that the z3fold page in which the allocation resides is under
1203 * reclaim, as indicated by the PG_reclaim flag being set, this function
1204 * only sets the first|last_chunks to 0. The page is actually freed
1205 * once both buddies are evicted (see z3fold_reclaim_page() below).
1207 static void z3fold_free(struct z3fold_pool
*pool
, unsigned long handle
)
1209 struct z3fold_header
*zhdr
;
1214 zhdr
= get_z3fold_header(handle
);
1215 page
= virt_to_page(zhdr
);
1216 page_claimed
= test_and_set_bit(PAGE_CLAIMED
, &page
->private);
1218 if (test_bit(PAGE_HEADLESS
, &page
->private)) {
1219 /* if a headless page is under reclaim, just leave.
1220 * NB: we use test_and_set_bit for a reason: if the bit
1221 * has not been set before, we release this page
1222 * immediately so we don't care about its value any more.
1224 if (!page_claimed
) {
1225 spin_lock(&pool
->lock
);
1226 list_del(&page
->lru
);
1227 spin_unlock(&pool
->lock
);
1228 put_z3fold_header(zhdr
);
1229 free_z3fold_page(page
, true);
1230 atomic64_dec(&pool
->pages_nr
);
1235 /* Non-headless case */
1236 bud
= handle_to_buddy(handle
);
1240 zhdr
->first_chunks
= 0;
1243 zhdr
->middle_chunks
= 0;
1246 zhdr
->last_chunks
= 0;
1249 pr_err("%s: unknown bud %d\n", __func__
, bud
);
1251 put_z3fold_header(zhdr
);
1256 free_handle(handle
, zhdr
);
1257 if (kref_put(&zhdr
->refcount
, release_z3fold_page_locked_list
)) {
1258 atomic64_dec(&pool
->pages_nr
);
1262 /* the page has not been claimed by us */
1263 z3fold_page_unlock(zhdr
);
1266 if (test_and_set_bit(NEEDS_COMPACTING
, &page
->private)) {
1267 put_z3fold_header(zhdr
);
1268 clear_bit(PAGE_CLAIMED
, &page
->private);
1271 if (zhdr
->cpu
< 0 || !cpu_online(zhdr
->cpu
)) {
1272 spin_lock(&pool
->lock
);
1273 list_del_init(&zhdr
->buddy
);
1274 spin_unlock(&pool
->lock
);
1276 kref_get(&zhdr
->refcount
);
1277 clear_bit(PAGE_CLAIMED
, &page
->private);
1278 do_compact_page(zhdr
, true);
1281 kref_get(&zhdr
->refcount
);
1282 clear_bit(PAGE_CLAIMED
, &page
->private);
1283 queue_work_on(zhdr
->cpu
, pool
->compact_wq
, &zhdr
->work
);
1284 put_z3fold_header(zhdr
);
1288 * z3fold_reclaim_page() - evicts allocations from a pool page and frees it
1289 * @pool: pool from which a page will attempt to be evicted
1290 * @retries: number of pages on the LRU list for which eviction will
1291 * be attempted before failing
1293 * z3fold reclaim is different from normal system reclaim in that it is done
1294 * from the bottom, up. This is because only the bottom layer, z3fold, has
1295 * information on how the allocations are organized within each z3fold page.
1296 * This has the potential to create interesting locking situations between
1297 * z3fold and the user, however.
1299 * To avoid these, this is how z3fold_reclaim_page() should be called:
1301 * The user detects a page should be reclaimed and calls z3fold_reclaim_page().
1302 * z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
1303 * call the user-defined eviction handler with the pool and handle as
1306 * If the handle can not be evicted, the eviction handler should return
1307 * non-zero. z3fold_reclaim_page() will add the z3fold page back to the
1308 * appropriate list and try the next z3fold page on the LRU up to
1309 * a user defined number of retries.
1311 * If the handle is successfully evicted, the eviction handler should
1312 * return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
1313 * contains logic to delay freeing the page if the page is under reclaim,
1314 * as indicated by the setting of the PG_reclaim flag on the underlying page.
1316 * If all buddies in the z3fold page are successfully evicted, then the
1317 * z3fold page can be freed.
1319 * Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
1320 * no pages to evict or an eviction handler is not registered, -EAGAIN if
1321 * the retry limit was hit.
1323 static int z3fold_reclaim_page(struct z3fold_pool
*pool
, unsigned int retries
)
1326 struct z3fold_header
*zhdr
= NULL
;
1327 struct page
*page
= NULL
;
1328 struct list_head
*pos
;
1329 unsigned long first_handle
= 0, middle_handle
= 0, last_handle
= 0;
1330 struct z3fold_buddy_slots slots
__attribute__((aligned(SLOTS_ALIGN
)));
1332 rwlock_init(&slots
.lock
);
1333 slots
.pool
= (unsigned long)pool
| (1 << HANDLES_NOFREE
);
1335 spin_lock(&pool
->lock
);
1336 if (!pool
->ops
|| !pool
->ops
->evict
|| retries
== 0) {
1337 spin_unlock(&pool
->lock
);
1340 for (i
= 0; i
< retries
; i
++) {
1341 if (list_empty(&pool
->lru
)) {
1342 spin_unlock(&pool
->lock
);
1345 list_for_each_prev(pos
, &pool
->lru
) {
1346 page
= list_entry(pos
, struct page
, lru
);
1348 zhdr
= page_address(page
);
1349 if (test_bit(PAGE_HEADLESS
, &page
->private))
1352 if (kref_get_unless_zero(&zhdr
->refcount
) == 0) {
1356 if (!z3fold_page_trylock(zhdr
)) {
1357 if (kref_put(&zhdr
->refcount
,
1358 release_z3fold_page
))
1359 atomic64_dec(&pool
->pages_nr
);
1361 continue; /* can't evict at this point */
1364 /* test_and_set_bit is of course atomic, but we still
1365 * need to do it under page lock, otherwise checking
1366 * that bit in __z3fold_alloc wouldn't make sense
1368 if (zhdr
->foreign_handles
||
1369 test_and_set_bit(PAGE_CLAIMED
, &page
->private)) {
1370 if (kref_put(&zhdr
->refcount
,
1371 release_z3fold_page
))
1372 atomic64_dec(&pool
->pages_nr
);
1374 z3fold_page_unlock(zhdr
);
1376 continue; /* can't evict such page */
1378 list_del_init(&zhdr
->buddy
);
1386 list_del_init(&page
->lru
);
1387 spin_unlock(&pool
->lock
);
1389 if (!test_bit(PAGE_HEADLESS
, &page
->private)) {
1391 * We need encode the handles before unlocking, and
1392 * use our local slots structure because z3fold_free
1393 * can zero out zhdr->slots and we can't do much
1399 memset(slots
.slot
, 0, sizeof(slots
.slot
));
1400 if (zhdr
->first_chunks
)
1401 first_handle
= __encode_handle(zhdr
, &slots
,
1403 if (zhdr
->middle_chunks
)
1404 middle_handle
= __encode_handle(zhdr
, &slots
,
1406 if (zhdr
->last_chunks
)
1407 last_handle
= __encode_handle(zhdr
, &slots
,
1410 * it's safe to unlock here because we hold a
1411 * reference to this page
1413 z3fold_page_unlock(zhdr
);
1415 first_handle
= encode_handle(zhdr
, HEADLESS
);
1416 last_handle
= middle_handle
= 0;
1418 /* Issue the eviction callback(s) */
1419 if (middle_handle
) {
1420 ret
= pool
->ops
->evict(pool
, middle_handle
);
1425 ret
= pool
->ops
->evict(pool
, first_handle
);
1430 ret
= pool
->ops
->evict(pool
, last_handle
);
1435 if (test_bit(PAGE_HEADLESS
, &page
->private)) {
1437 free_z3fold_page(page
, true);
1438 atomic64_dec(&pool
->pages_nr
);
1441 spin_lock(&pool
->lock
);
1442 list_add(&page
->lru
, &pool
->lru
);
1443 spin_unlock(&pool
->lock
);
1444 clear_bit(PAGE_CLAIMED
, &page
->private);
1446 struct z3fold_buddy_slots
*slots
= zhdr
->slots
;
1447 z3fold_page_lock(zhdr
);
1448 if (kref_put(&zhdr
->refcount
,
1449 release_z3fold_page_locked
)) {
1450 kmem_cache_free(pool
->c_handle
, slots
);
1451 atomic64_dec(&pool
->pages_nr
);
1455 * if we are here, the page is still not completely
1456 * free. Take the global pool lock then to be able
1457 * to add it back to the lru list
1459 spin_lock(&pool
->lock
);
1460 list_add(&page
->lru
, &pool
->lru
);
1461 spin_unlock(&pool
->lock
);
1462 z3fold_page_unlock(zhdr
);
1463 clear_bit(PAGE_CLAIMED
, &page
->private);
1466 /* We started off locked to we need to lock the pool back */
1467 spin_lock(&pool
->lock
);
1469 spin_unlock(&pool
->lock
);
1474 * z3fold_map() - maps the allocation associated with the given handle
1475 * @pool: pool in which the allocation resides
1476 * @handle: handle associated with the allocation to be mapped
1478 * Extracts the buddy number from handle and constructs the pointer to the
1479 * correct starting chunk within the page.
1481 * Returns: a pointer to the mapped allocation
1483 static void *z3fold_map(struct z3fold_pool
*pool
, unsigned long handle
)
1485 struct z3fold_header
*zhdr
;
1490 zhdr
= get_z3fold_header(handle
);
1492 page
= virt_to_page(zhdr
);
1494 if (test_bit(PAGE_HEADLESS
, &page
->private))
1497 buddy
= handle_to_buddy(handle
);
1500 addr
+= ZHDR_SIZE_ALIGNED
;
1503 addr
+= zhdr
->start_middle
<< CHUNK_SHIFT
;
1504 set_bit(MIDDLE_CHUNK_MAPPED
, &page
->private);
1507 addr
+= PAGE_SIZE
- (handle_to_chunks(handle
) << CHUNK_SHIFT
);
1510 pr_err("unknown buddy id %d\n", buddy
);
1517 zhdr
->mapped_count
++;
1519 put_z3fold_header(zhdr
);
1524 * z3fold_unmap() - unmaps the allocation associated with the given handle
1525 * @pool: pool in which the allocation resides
1526 * @handle: handle associated with the allocation to be unmapped
1528 static void z3fold_unmap(struct z3fold_pool
*pool
, unsigned long handle
)
1530 struct z3fold_header
*zhdr
;
1534 zhdr
= get_z3fold_header(handle
);
1535 page
= virt_to_page(zhdr
);
1537 if (test_bit(PAGE_HEADLESS
, &page
->private))
1540 buddy
= handle_to_buddy(handle
);
1541 if (buddy
== MIDDLE
)
1542 clear_bit(MIDDLE_CHUNK_MAPPED
, &page
->private);
1543 zhdr
->mapped_count
--;
1544 put_z3fold_header(zhdr
);
1548 * z3fold_get_pool_size() - gets the z3fold pool size in pages
1549 * @pool: pool whose size is being queried
1551 * Returns: size in pages of the given pool.
1553 static u64
z3fold_get_pool_size(struct z3fold_pool
*pool
)
1555 return atomic64_read(&pool
->pages_nr
);
1558 static bool z3fold_page_isolate(struct page
*page
, isolate_mode_t mode
)
1560 struct z3fold_header
*zhdr
;
1561 struct z3fold_pool
*pool
;
1563 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
1564 VM_BUG_ON_PAGE(PageIsolated(page
), page
);
1566 if (test_bit(PAGE_HEADLESS
, &page
->private))
1569 zhdr
= page_address(page
);
1570 z3fold_page_lock(zhdr
);
1571 if (test_bit(NEEDS_COMPACTING
, &page
->private) ||
1572 test_bit(PAGE_STALE
, &page
->private))
1575 if (zhdr
->mapped_count
!= 0 || zhdr
->foreign_handles
!= 0)
1578 if (test_and_set_bit(PAGE_CLAIMED
, &page
->private))
1580 pool
= zhdr_to_pool(zhdr
);
1581 spin_lock(&pool
->lock
);
1582 if (!list_empty(&zhdr
->buddy
))
1583 list_del_init(&zhdr
->buddy
);
1584 if (!list_empty(&page
->lru
))
1585 list_del_init(&page
->lru
);
1586 spin_unlock(&pool
->lock
);
1588 kref_get(&zhdr
->refcount
);
1589 z3fold_page_unlock(zhdr
);
1593 z3fold_page_unlock(zhdr
);
1597 static int z3fold_page_migrate(struct address_space
*mapping
, struct page
*newpage
,
1598 struct page
*page
, enum migrate_mode mode
)
1600 struct z3fold_header
*zhdr
, *new_zhdr
;
1601 struct z3fold_pool
*pool
;
1602 struct address_space
*new_mapping
;
1604 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
1605 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
1606 VM_BUG_ON_PAGE(!test_bit(PAGE_CLAIMED
, &page
->private), page
);
1607 VM_BUG_ON_PAGE(!PageLocked(newpage
), newpage
);
1609 zhdr
= page_address(page
);
1610 pool
= zhdr_to_pool(zhdr
);
1612 if (!z3fold_page_trylock(zhdr
))
1614 if (zhdr
->mapped_count
!= 0 || zhdr
->foreign_handles
!= 0) {
1615 z3fold_page_unlock(zhdr
);
1616 clear_bit(PAGE_CLAIMED
, &page
->private);
1619 if (work_pending(&zhdr
->work
)) {
1620 z3fold_page_unlock(zhdr
);
1623 new_zhdr
= page_address(newpage
);
1624 memcpy(new_zhdr
, zhdr
, PAGE_SIZE
);
1625 newpage
->private = page
->private;
1627 z3fold_page_unlock(zhdr
);
1628 spin_lock_init(&new_zhdr
->page_lock
);
1629 INIT_WORK(&new_zhdr
->work
, compact_page_work
);
1631 * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
1632 * so we only have to reinitialize it.
1634 INIT_LIST_HEAD(&new_zhdr
->buddy
);
1635 new_mapping
= page_mapping(page
);
1636 __ClearPageMovable(page
);
1637 ClearPagePrivate(page
);
1640 z3fold_page_lock(new_zhdr
);
1641 if (new_zhdr
->first_chunks
)
1642 encode_handle(new_zhdr
, FIRST
);
1643 if (new_zhdr
->last_chunks
)
1644 encode_handle(new_zhdr
, LAST
);
1645 if (new_zhdr
->middle_chunks
)
1646 encode_handle(new_zhdr
, MIDDLE
);
1647 set_bit(NEEDS_COMPACTING
, &newpage
->private);
1648 new_zhdr
->cpu
= smp_processor_id();
1649 spin_lock(&pool
->lock
);
1650 list_add(&newpage
->lru
, &pool
->lru
);
1651 spin_unlock(&pool
->lock
);
1652 __SetPageMovable(newpage
, new_mapping
);
1653 z3fold_page_unlock(new_zhdr
);
1655 queue_work_on(new_zhdr
->cpu
, pool
->compact_wq
, &new_zhdr
->work
);
1657 page_mapcount_reset(page
);
1658 clear_bit(PAGE_CLAIMED
, &page
->private);
1663 static void z3fold_page_putback(struct page
*page
)
1665 struct z3fold_header
*zhdr
;
1666 struct z3fold_pool
*pool
;
1668 zhdr
= page_address(page
);
1669 pool
= zhdr_to_pool(zhdr
);
1671 z3fold_page_lock(zhdr
);
1672 if (!list_empty(&zhdr
->buddy
))
1673 list_del_init(&zhdr
->buddy
);
1674 INIT_LIST_HEAD(&page
->lru
);
1675 if (kref_put(&zhdr
->refcount
, release_z3fold_page_locked
)) {
1676 atomic64_dec(&pool
->pages_nr
);
1679 spin_lock(&pool
->lock
);
1680 list_add(&page
->lru
, &pool
->lru
);
1681 spin_unlock(&pool
->lock
);
1682 clear_bit(PAGE_CLAIMED
, &page
->private);
1683 z3fold_page_unlock(zhdr
);
1686 static const struct address_space_operations z3fold_aops
= {
1687 .isolate_page
= z3fold_page_isolate
,
1688 .migratepage
= z3fold_page_migrate
,
1689 .putback_page
= z3fold_page_putback
,
1696 static int z3fold_zpool_evict(struct z3fold_pool
*pool
, unsigned long handle
)
1698 if (pool
->zpool
&& pool
->zpool_ops
&& pool
->zpool_ops
->evict
)
1699 return pool
->zpool_ops
->evict(pool
->zpool
, handle
);
1704 static const struct z3fold_ops z3fold_zpool_ops
= {
1705 .evict
= z3fold_zpool_evict
1708 static void *z3fold_zpool_create(const char *name
, gfp_t gfp
,
1709 const struct zpool_ops
*zpool_ops
,
1710 struct zpool
*zpool
)
1712 struct z3fold_pool
*pool
;
1714 pool
= z3fold_create_pool(name
, gfp
,
1715 zpool_ops
? &z3fold_zpool_ops
: NULL
);
1717 pool
->zpool
= zpool
;
1718 pool
->zpool_ops
= zpool_ops
;
1723 static void z3fold_zpool_destroy(void *pool
)
1725 z3fold_destroy_pool(pool
);
1728 static int z3fold_zpool_malloc(void *pool
, size_t size
, gfp_t gfp
,
1729 unsigned long *handle
)
1731 return z3fold_alloc(pool
, size
, gfp
, handle
);
1733 static void z3fold_zpool_free(void *pool
, unsigned long handle
)
1735 z3fold_free(pool
, handle
);
1738 static int z3fold_zpool_shrink(void *pool
, unsigned int pages
,
1739 unsigned int *reclaimed
)
1741 unsigned int total
= 0;
1744 while (total
< pages
) {
1745 ret
= z3fold_reclaim_page(pool
, 8);
1757 static void *z3fold_zpool_map(void *pool
, unsigned long handle
,
1758 enum zpool_mapmode mm
)
1760 return z3fold_map(pool
, handle
);
1762 static void z3fold_zpool_unmap(void *pool
, unsigned long handle
)
1764 z3fold_unmap(pool
, handle
);
1767 static u64
z3fold_zpool_total_size(void *pool
)
1769 return z3fold_get_pool_size(pool
) * PAGE_SIZE
;
1772 static struct zpool_driver z3fold_zpool_driver
= {
1774 .sleep_mapped
= true,
1775 .owner
= THIS_MODULE
,
1776 .create
= z3fold_zpool_create
,
1777 .destroy
= z3fold_zpool_destroy
,
1778 .malloc
= z3fold_zpool_malloc
,
1779 .free
= z3fold_zpool_free
,
1780 .shrink
= z3fold_zpool_shrink
,
1781 .map
= z3fold_zpool_map
,
1782 .unmap
= z3fold_zpool_unmap
,
1783 .total_size
= z3fold_zpool_total_size
,
1786 MODULE_ALIAS("zpool-z3fold");
1788 static int __init
init_z3fold(void)
1792 /* Make sure the z3fold header is not larger than the page size */
1793 BUILD_BUG_ON(ZHDR_SIZE_ALIGNED
> PAGE_SIZE
);
1794 ret
= z3fold_mount();
1798 zpool_register_driver(&z3fold_zpool_driver
);
1803 static void __exit
exit_z3fold(void)
1806 zpool_unregister_driver(&z3fold_zpool_driver
);
1809 module_init(init_z3fold
);
1810 module_exit(exit_z3fold
);
1812 MODULE_LICENSE("GPL");
1813 MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
1814 MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");