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 + flags */
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
{
188 HANDLES_ORPHANED
= 0,
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
)
308 struct z3fold_buddy_slots
*slots
;
309 struct z3fold_header
*zhdr
;
313 if (handle
& (1 << PAGE_HEADLESS
))
316 if (WARN_ON(*(unsigned long *)handle
== 0))
319 zhdr
= handle_to_z3fold_header(handle
);
320 slots
= handle_to_slots(handle
);
321 write_lock(&slots
->lock
);
322 *(unsigned long *)handle
= 0;
323 if (zhdr
->slots
== slots
) {
324 write_unlock(&slots
->lock
);
325 return; /* simple case, nothing else to do */
328 /* we are freeing a foreign handle if we are here */
329 zhdr
->foreign_handles
--;
331 if (!test_bit(HANDLES_ORPHANED
, &slots
->pool
)) {
332 write_unlock(&slots
->lock
);
335 for (i
= 0; i
<= BUDDY_MASK
; i
++) {
336 if (slots
->slot
[i
]) {
341 write_unlock(&slots
->lock
);
344 struct z3fold_pool
*pool
= slots_to_pool(slots
);
346 kmem_cache_free(pool
->c_handle
, slots
);
350 static int z3fold_init_fs_context(struct fs_context
*fc
)
352 return init_pseudo(fc
, Z3FOLD_MAGIC
) ? 0 : -ENOMEM
;
355 static struct file_system_type z3fold_fs
= {
357 .init_fs_context
= z3fold_init_fs_context
,
358 .kill_sb
= kill_anon_super
,
361 static struct vfsmount
*z3fold_mnt
;
362 static int z3fold_mount(void)
366 z3fold_mnt
= kern_mount(&z3fold_fs
);
367 if (IS_ERR(z3fold_mnt
))
368 ret
= PTR_ERR(z3fold_mnt
);
373 static void z3fold_unmount(void)
375 kern_unmount(z3fold_mnt
);
378 static const struct address_space_operations z3fold_aops
;
379 static int z3fold_register_migration(struct z3fold_pool
*pool
)
381 pool
->inode
= alloc_anon_inode(z3fold_mnt
->mnt_sb
);
382 if (IS_ERR(pool
->inode
)) {
387 pool
->inode
->i_mapping
->private_data
= pool
;
388 pool
->inode
->i_mapping
->a_ops
= &z3fold_aops
;
392 static void z3fold_unregister_migration(struct z3fold_pool
*pool
)
398 /* Initializes the z3fold header of a newly allocated z3fold page */
399 static struct z3fold_header
*init_z3fold_page(struct page
*page
, bool headless
,
400 struct z3fold_pool
*pool
, gfp_t gfp
)
402 struct z3fold_header
*zhdr
= page_address(page
);
403 struct z3fold_buddy_slots
*slots
;
405 INIT_LIST_HEAD(&page
->lru
);
406 clear_bit(PAGE_HEADLESS
, &page
->private);
407 clear_bit(MIDDLE_CHUNK_MAPPED
, &page
->private);
408 clear_bit(NEEDS_COMPACTING
, &page
->private);
409 clear_bit(PAGE_STALE
, &page
->private);
410 clear_bit(PAGE_CLAIMED
, &page
->private);
414 slots
= alloc_slots(pool
, gfp
);
418 spin_lock_init(&zhdr
->page_lock
);
419 kref_init(&zhdr
->refcount
);
420 zhdr
->first_chunks
= 0;
421 zhdr
->middle_chunks
= 0;
422 zhdr
->last_chunks
= 0;
424 zhdr
->start_middle
= 0;
426 zhdr
->foreign_handles
= 0;
427 zhdr
->mapped_count
= 0;
430 INIT_LIST_HEAD(&zhdr
->buddy
);
431 INIT_WORK(&zhdr
->work
, compact_page_work
);
435 /* Resets the struct page fields and frees the page */
436 static void free_z3fold_page(struct page
*page
, bool headless
)
440 __ClearPageMovable(page
);
443 ClearPagePrivate(page
);
447 /* Helper function to build the index */
448 static inline int __idx(struct z3fold_header
*zhdr
, enum buddy bud
)
450 return (bud
+ zhdr
->first_num
) & BUDDY_MASK
;
454 * Encodes the handle of a particular buddy within a z3fold page
455 * Pool lock should be held as this function accesses first_num
457 static unsigned long __encode_handle(struct z3fold_header
*zhdr
,
458 struct z3fold_buddy_slots
*slots
,
461 unsigned long h
= (unsigned long)zhdr
;
465 * For a headless page, its handle is its pointer with the extra
466 * PAGE_HEADLESS bit set
469 return h
| (1 << PAGE_HEADLESS
);
471 /* otherwise, return pointer to encoded handle */
472 idx
= __idx(zhdr
, bud
);
475 h
|= (zhdr
->last_chunks
<< BUDDY_SHIFT
);
477 write_lock(&slots
->lock
);
478 slots
->slot
[idx
] = h
;
479 write_unlock(&slots
->lock
);
480 return (unsigned long)&slots
->slot
[idx
];
483 static unsigned long encode_handle(struct z3fold_header
*zhdr
, enum buddy bud
)
485 return __encode_handle(zhdr
, zhdr
->slots
, bud
);
488 /* only for LAST bud, returns zero otherwise */
489 static unsigned short handle_to_chunks(unsigned long handle
)
491 struct z3fold_buddy_slots
*slots
= handle_to_slots(handle
);
494 read_lock(&slots
->lock
);
495 addr
= *(unsigned long *)handle
;
496 read_unlock(&slots
->lock
);
497 return (addr
& ~PAGE_MASK
) >> BUDDY_SHIFT
;
501 * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
502 * but that doesn't matter. because the masking will result in the
503 * correct buddy number.
505 static enum buddy
handle_to_buddy(unsigned long handle
)
507 struct z3fold_header
*zhdr
;
508 struct z3fold_buddy_slots
*slots
= handle_to_slots(handle
);
511 read_lock(&slots
->lock
);
512 WARN_ON(handle
& (1 << PAGE_HEADLESS
));
513 addr
= *(unsigned long *)handle
;
514 read_unlock(&slots
->lock
);
515 zhdr
= (struct z3fold_header
*)(addr
& PAGE_MASK
);
516 return (addr
- zhdr
->first_num
) & BUDDY_MASK
;
519 static inline struct z3fold_pool
*zhdr_to_pool(struct z3fold_header
*zhdr
)
524 static void __release_z3fold_page(struct z3fold_header
*zhdr
, bool locked
)
526 struct page
*page
= virt_to_page(zhdr
);
527 struct z3fold_pool
*pool
= zhdr_to_pool(zhdr
);
531 WARN_ON(!list_empty(&zhdr
->buddy
));
532 set_bit(PAGE_STALE
, &page
->private);
533 clear_bit(NEEDS_COMPACTING
, &page
->private);
534 spin_lock(&pool
->lock
);
535 if (!list_empty(&page
->lru
))
536 list_del_init(&page
->lru
);
537 spin_unlock(&pool
->lock
);
539 /* If there are no foreign handles, free the handles array */
540 read_lock(&zhdr
->slots
->lock
);
541 for (i
= 0; i
<= BUDDY_MASK
; i
++) {
542 if (zhdr
->slots
->slot
[i
]) {
548 set_bit(HANDLES_ORPHANED
, &zhdr
->slots
->pool
);
549 read_unlock(&zhdr
->slots
->lock
);
552 kmem_cache_free(pool
->c_handle
, zhdr
->slots
);
555 z3fold_page_unlock(zhdr
);
557 spin_lock(&pool
->stale_lock
);
558 list_add(&zhdr
->buddy
, &pool
->stale
);
559 queue_work(pool
->release_wq
, &pool
->work
);
560 spin_unlock(&pool
->stale_lock
);
563 static void __attribute__((__unused__
))
564 release_z3fold_page(struct kref
*ref
)
566 struct z3fold_header
*zhdr
= container_of(ref
, struct z3fold_header
,
568 __release_z3fold_page(zhdr
, false);
571 static void release_z3fold_page_locked(struct kref
*ref
)
573 struct z3fold_header
*zhdr
= container_of(ref
, struct z3fold_header
,
575 WARN_ON(z3fold_page_trylock(zhdr
));
576 __release_z3fold_page(zhdr
, true);
579 static void release_z3fold_page_locked_list(struct kref
*ref
)
581 struct z3fold_header
*zhdr
= container_of(ref
, struct z3fold_header
,
583 struct z3fold_pool
*pool
= zhdr_to_pool(zhdr
);
585 spin_lock(&pool
->lock
);
586 list_del_init(&zhdr
->buddy
);
587 spin_unlock(&pool
->lock
);
589 WARN_ON(z3fold_page_trylock(zhdr
));
590 __release_z3fold_page(zhdr
, true);
593 static void free_pages_work(struct work_struct
*w
)
595 struct z3fold_pool
*pool
= container_of(w
, struct z3fold_pool
, work
);
597 spin_lock(&pool
->stale_lock
);
598 while (!list_empty(&pool
->stale
)) {
599 struct z3fold_header
*zhdr
= list_first_entry(&pool
->stale
,
600 struct z3fold_header
, buddy
);
601 struct page
*page
= virt_to_page(zhdr
);
603 list_del(&zhdr
->buddy
);
604 if (WARN_ON(!test_bit(PAGE_STALE
, &page
->private)))
606 spin_unlock(&pool
->stale_lock
);
607 cancel_work_sync(&zhdr
->work
);
608 free_z3fold_page(page
, false);
610 spin_lock(&pool
->stale_lock
);
612 spin_unlock(&pool
->stale_lock
);
616 * Returns the number of free chunks in a z3fold page.
617 * NB: can't be used with HEADLESS pages.
619 static int num_free_chunks(struct z3fold_header
*zhdr
)
623 * If there is a middle object, pick up the bigger free space
624 * either before or after it. Otherwise just subtract the number
625 * of chunks occupied by the first and the last objects.
627 if (zhdr
->middle_chunks
!= 0) {
628 int nfree_before
= zhdr
->first_chunks
?
629 0 : zhdr
->start_middle
- ZHDR_CHUNKS
;
630 int nfree_after
= zhdr
->last_chunks
?
632 (zhdr
->start_middle
+ zhdr
->middle_chunks
);
633 nfree
= max(nfree_before
, nfree_after
);
635 nfree
= NCHUNKS
- zhdr
->first_chunks
- zhdr
->last_chunks
;
639 /* Add to the appropriate unbuddied list */
640 static inline void add_to_unbuddied(struct z3fold_pool
*pool
,
641 struct z3fold_header
*zhdr
)
643 if (zhdr
->first_chunks
== 0 || zhdr
->last_chunks
== 0 ||
644 zhdr
->middle_chunks
== 0) {
645 struct list_head
*unbuddied
= get_cpu_ptr(pool
->unbuddied
);
647 int freechunks
= num_free_chunks(zhdr
);
648 spin_lock(&pool
->lock
);
649 list_add(&zhdr
->buddy
, &unbuddied
[freechunks
]);
650 spin_unlock(&pool
->lock
);
651 zhdr
->cpu
= smp_processor_id();
652 put_cpu_ptr(pool
->unbuddied
);
656 static inline void *mchunk_memmove(struct z3fold_header
*zhdr
,
657 unsigned short dst_chunk
)
660 return memmove(beg
+ (dst_chunk
<< CHUNK_SHIFT
),
661 beg
+ (zhdr
->start_middle
<< CHUNK_SHIFT
),
662 zhdr
->middle_chunks
<< CHUNK_SHIFT
);
665 static inline bool buddy_single(struct z3fold_header
*zhdr
)
667 return !((zhdr
->first_chunks
&& zhdr
->middle_chunks
) ||
668 (zhdr
->first_chunks
&& zhdr
->last_chunks
) ||
669 (zhdr
->middle_chunks
&& zhdr
->last_chunks
));
672 static struct z3fold_header
*compact_single_buddy(struct z3fold_header
*zhdr
)
674 struct z3fold_pool
*pool
= zhdr_to_pool(zhdr
);
676 unsigned long old_handle
= 0;
678 struct z3fold_header
*new_zhdr
= NULL
;
679 int first_idx
= __idx(zhdr
, FIRST
);
680 int middle_idx
= __idx(zhdr
, MIDDLE
);
681 int last_idx
= __idx(zhdr
, LAST
);
682 unsigned short *moved_chunks
= NULL
;
685 * No need to protect slots here -- all the slots are "local" and
686 * the page lock is already taken
688 if (zhdr
->first_chunks
&& zhdr
->slots
->slot
[first_idx
]) {
689 p
+= ZHDR_SIZE_ALIGNED
;
690 sz
= zhdr
->first_chunks
<< CHUNK_SHIFT
;
691 old_handle
= (unsigned long)&zhdr
->slots
->slot
[first_idx
];
692 moved_chunks
= &zhdr
->first_chunks
;
693 } else if (zhdr
->middle_chunks
&& zhdr
->slots
->slot
[middle_idx
]) {
694 p
+= zhdr
->start_middle
<< CHUNK_SHIFT
;
695 sz
= zhdr
->middle_chunks
<< CHUNK_SHIFT
;
696 old_handle
= (unsigned long)&zhdr
->slots
->slot
[middle_idx
];
697 moved_chunks
= &zhdr
->middle_chunks
;
698 } else if (zhdr
->last_chunks
&& zhdr
->slots
->slot
[last_idx
]) {
699 p
+= PAGE_SIZE
- (zhdr
->last_chunks
<< CHUNK_SHIFT
);
700 sz
= zhdr
->last_chunks
<< CHUNK_SHIFT
;
701 old_handle
= (unsigned long)&zhdr
->slots
->slot
[last_idx
];
702 moved_chunks
= &zhdr
->last_chunks
;
706 enum buddy new_bud
= HEADLESS
;
707 short chunks
= size_to_chunks(sz
);
710 new_zhdr
= __z3fold_alloc(pool
, sz
, false);
714 if (WARN_ON(new_zhdr
== zhdr
))
717 if (new_zhdr
->first_chunks
== 0) {
718 if (new_zhdr
->middle_chunks
!= 0 &&
719 chunks
>= new_zhdr
->start_middle
) {
724 } else if (new_zhdr
->last_chunks
== 0) {
726 } else if (new_zhdr
->middle_chunks
== 0) {
732 new_zhdr
->first_chunks
= chunks
;
733 q
+= ZHDR_SIZE_ALIGNED
;
736 new_zhdr
->middle_chunks
= chunks
;
737 new_zhdr
->start_middle
=
738 new_zhdr
->first_chunks
+ ZHDR_CHUNKS
;
739 q
+= new_zhdr
->start_middle
<< CHUNK_SHIFT
;
742 new_zhdr
->last_chunks
= chunks
;
743 q
+= PAGE_SIZE
- (new_zhdr
->last_chunks
<< CHUNK_SHIFT
);
748 new_zhdr
->foreign_handles
++;
750 write_lock(&zhdr
->slots
->lock
);
751 *(unsigned long *)old_handle
= (unsigned long)new_zhdr
+
752 __idx(new_zhdr
, new_bud
);
754 *(unsigned long *)old_handle
|=
755 (new_zhdr
->last_chunks
<< BUDDY_SHIFT
);
756 write_unlock(&zhdr
->slots
->lock
);
757 add_to_unbuddied(pool
, new_zhdr
);
758 z3fold_page_unlock(new_zhdr
);
767 if (kref_put(&new_zhdr
->refcount
, release_z3fold_page_locked
))
768 atomic64_dec(&pool
->pages_nr
);
770 add_to_unbuddied(pool
, new_zhdr
);
771 z3fold_page_unlock(new_zhdr
);
778 #define BIG_CHUNK_GAP 3
779 /* Has to be called with lock held */
780 static int z3fold_compact_page(struct z3fold_header
*zhdr
)
782 struct page
*page
= virt_to_page(zhdr
);
784 if (test_bit(MIDDLE_CHUNK_MAPPED
, &page
->private))
785 return 0; /* can't move middle chunk, it's used */
787 if (unlikely(PageIsolated(page
)))
790 if (zhdr
->middle_chunks
== 0)
791 return 0; /* nothing to compact */
793 if (zhdr
->first_chunks
== 0 && zhdr
->last_chunks
== 0) {
794 /* move to the beginning */
795 mchunk_memmove(zhdr
, ZHDR_CHUNKS
);
796 zhdr
->first_chunks
= zhdr
->middle_chunks
;
797 zhdr
->middle_chunks
= 0;
798 zhdr
->start_middle
= 0;
804 * moving data is expensive, so let's only do that if
805 * there's substantial gain (at least BIG_CHUNK_GAP chunks)
807 if (zhdr
->first_chunks
!= 0 && zhdr
->last_chunks
== 0 &&
808 zhdr
->start_middle
- (zhdr
->first_chunks
+ ZHDR_CHUNKS
) >=
810 mchunk_memmove(zhdr
, zhdr
->first_chunks
+ ZHDR_CHUNKS
);
811 zhdr
->start_middle
= zhdr
->first_chunks
+ ZHDR_CHUNKS
;
813 } else if (zhdr
->last_chunks
!= 0 && zhdr
->first_chunks
== 0 &&
814 TOTAL_CHUNKS
- (zhdr
->last_chunks
+ zhdr
->start_middle
815 + zhdr
->middle_chunks
) >=
817 unsigned short new_start
= TOTAL_CHUNKS
- zhdr
->last_chunks
-
819 mchunk_memmove(zhdr
, new_start
);
820 zhdr
->start_middle
= new_start
;
827 static void do_compact_page(struct z3fold_header
*zhdr
, bool locked
)
829 struct z3fold_pool
*pool
= zhdr_to_pool(zhdr
);
832 page
= virt_to_page(zhdr
);
834 WARN_ON(z3fold_page_trylock(zhdr
));
836 z3fold_page_lock(zhdr
);
837 if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING
, &page
->private))) {
838 z3fold_page_unlock(zhdr
);
841 spin_lock(&pool
->lock
);
842 list_del_init(&zhdr
->buddy
);
843 spin_unlock(&pool
->lock
);
845 if (kref_put(&zhdr
->refcount
, release_z3fold_page_locked
)) {
846 atomic64_dec(&pool
->pages_nr
);
850 if (unlikely(PageIsolated(page
) ||
851 test_bit(PAGE_CLAIMED
, &page
->private) ||
852 test_bit(PAGE_STALE
, &page
->private))) {
853 z3fold_page_unlock(zhdr
);
857 if (!zhdr
->foreign_handles
&& buddy_single(zhdr
) &&
858 zhdr
->mapped_count
== 0 && compact_single_buddy(zhdr
)) {
859 if (kref_put(&zhdr
->refcount
, release_z3fold_page_locked
))
860 atomic64_dec(&pool
->pages_nr
);
862 z3fold_page_unlock(zhdr
);
866 z3fold_compact_page(zhdr
);
867 add_to_unbuddied(pool
, zhdr
);
868 z3fold_page_unlock(zhdr
);
871 static void compact_page_work(struct work_struct
*w
)
873 struct z3fold_header
*zhdr
= container_of(w
, struct z3fold_header
,
876 do_compact_page(zhdr
, false);
879 /* returns _locked_ z3fold page header or NULL */
880 static inline struct z3fold_header
*__z3fold_alloc(struct z3fold_pool
*pool
,
881 size_t size
, bool can_sleep
)
883 struct z3fold_header
*zhdr
= NULL
;
885 struct list_head
*unbuddied
;
886 int chunks
= size_to_chunks(size
), i
;
889 /* First, try to find an unbuddied z3fold page. */
890 unbuddied
= get_cpu_ptr(pool
->unbuddied
);
891 for_each_unbuddied_list(i
, chunks
) {
892 struct list_head
*l
= &unbuddied
[i
];
894 zhdr
= list_first_entry_or_null(READ_ONCE(l
),
895 struct z3fold_header
, buddy
);
900 /* Re-check under lock. */
901 spin_lock(&pool
->lock
);
903 if (unlikely(zhdr
!= list_first_entry(READ_ONCE(l
),
904 struct z3fold_header
, buddy
)) ||
905 !z3fold_page_trylock(zhdr
)) {
906 spin_unlock(&pool
->lock
);
908 put_cpu_ptr(pool
->unbuddied
);
913 list_del_init(&zhdr
->buddy
);
915 spin_unlock(&pool
->lock
);
917 page
= virt_to_page(zhdr
);
918 if (test_bit(NEEDS_COMPACTING
, &page
->private) ||
919 test_bit(PAGE_CLAIMED
, &page
->private)) {
920 z3fold_page_unlock(zhdr
);
922 put_cpu_ptr(pool
->unbuddied
);
929 * this page could not be removed from its unbuddied
930 * list while pool lock was held, and then we've taken
931 * page lock so kref_put could not be called before
932 * we got here, so it's safe to just call kref_get()
934 kref_get(&zhdr
->refcount
);
937 put_cpu_ptr(pool
->unbuddied
);
942 /* look for _exact_ match on other cpus' lists */
943 for_each_online_cpu(cpu
) {
946 unbuddied
= per_cpu_ptr(pool
->unbuddied
, cpu
);
947 spin_lock(&pool
->lock
);
948 l
= &unbuddied
[chunks
];
950 zhdr
= list_first_entry_or_null(READ_ONCE(l
),
951 struct z3fold_header
, buddy
);
953 if (!zhdr
|| !z3fold_page_trylock(zhdr
)) {
954 spin_unlock(&pool
->lock
);
958 list_del_init(&zhdr
->buddy
);
960 spin_unlock(&pool
->lock
);
962 page
= virt_to_page(zhdr
);
963 if (test_bit(NEEDS_COMPACTING
, &page
->private) ||
964 test_bit(PAGE_CLAIMED
, &page
->private)) {
965 z3fold_page_unlock(zhdr
);
971 kref_get(&zhdr
->refcount
);
984 * z3fold_create_pool() - create a new z3fold pool
986 * @gfp: gfp flags when allocating the z3fold pool structure
987 * @ops: user-defined operations for the z3fold pool
989 * Return: pointer to the new z3fold pool or NULL if the metadata allocation
992 static struct z3fold_pool
*z3fold_create_pool(const char *name
, gfp_t gfp
,
993 const struct z3fold_ops
*ops
)
995 struct z3fold_pool
*pool
= NULL
;
998 pool
= kzalloc(sizeof(struct z3fold_pool
), gfp
);
1001 pool
->c_handle
= kmem_cache_create("z3fold_handle",
1002 sizeof(struct z3fold_buddy_slots
),
1003 SLOTS_ALIGN
, 0, NULL
);
1004 if (!pool
->c_handle
)
1006 spin_lock_init(&pool
->lock
);
1007 spin_lock_init(&pool
->stale_lock
);
1008 pool
->unbuddied
= __alloc_percpu(sizeof(struct list_head
)*NCHUNKS
, 2);
1009 if (!pool
->unbuddied
)
1011 for_each_possible_cpu(cpu
) {
1012 struct list_head
*unbuddied
=
1013 per_cpu_ptr(pool
->unbuddied
, cpu
);
1014 for_each_unbuddied_list(i
, 0)
1015 INIT_LIST_HEAD(&unbuddied
[i
]);
1017 INIT_LIST_HEAD(&pool
->lru
);
1018 INIT_LIST_HEAD(&pool
->stale
);
1019 atomic64_set(&pool
->pages_nr
, 0);
1021 pool
->compact_wq
= create_singlethread_workqueue(pool
->name
);
1022 if (!pool
->compact_wq
)
1024 pool
->release_wq
= create_singlethread_workqueue(pool
->name
);
1025 if (!pool
->release_wq
)
1027 if (z3fold_register_migration(pool
))
1029 INIT_WORK(&pool
->work
, free_pages_work
);
1034 destroy_workqueue(pool
->release_wq
);
1036 destroy_workqueue(pool
->compact_wq
);
1038 free_percpu(pool
->unbuddied
);
1040 kmem_cache_destroy(pool
->c_handle
);
1048 * z3fold_destroy_pool() - destroys an existing z3fold pool
1049 * @pool: the z3fold pool to be destroyed
1051 * The pool should be emptied before this function is called.
1053 static void z3fold_destroy_pool(struct z3fold_pool
*pool
)
1055 kmem_cache_destroy(pool
->c_handle
);
1058 * We need to destroy pool->compact_wq before pool->release_wq,
1059 * as any pending work on pool->compact_wq will call
1060 * queue_work(pool->release_wq, &pool->work).
1062 * There are still outstanding pages until both workqueues are drained,
1063 * so we cannot unregister migration until then.
1066 destroy_workqueue(pool
->compact_wq
);
1067 destroy_workqueue(pool
->release_wq
);
1068 z3fold_unregister_migration(pool
);
1073 * z3fold_alloc() - allocates a region of a given size
1074 * @pool: z3fold pool from which to allocate
1075 * @size: size in bytes of the desired allocation
1076 * @gfp: gfp flags used if the pool needs to grow
1077 * @handle: handle of the new allocation
1079 * This function will attempt to find a free region in the pool large enough to
1080 * satisfy the allocation request. A search of the unbuddied lists is
1081 * performed first. If no suitable free region is found, then a new page is
1082 * allocated and added to the pool to satisfy the request.
1084 * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
1085 * as z3fold pool pages.
1087 * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
1088 * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
1091 static int z3fold_alloc(struct z3fold_pool
*pool
, size_t size
, gfp_t gfp
,
1092 unsigned long *handle
)
1094 int chunks
= size_to_chunks(size
);
1095 struct z3fold_header
*zhdr
= NULL
;
1096 struct page
*page
= NULL
;
1098 bool can_sleep
= gfpflags_allow_blocking(gfp
);
1103 if (size
> PAGE_SIZE
)
1106 if (size
> PAGE_SIZE
- ZHDR_SIZE_ALIGNED
- CHUNK_SIZE
)
1110 zhdr
= __z3fold_alloc(pool
, size
, can_sleep
);
1112 if (zhdr
->first_chunks
== 0) {
1113 if (zhdr
->middle_chunks
!= 0 &&
1114 chunks
>= zhdr
->start_middle
)
1118 } else if (zhdr
->last_chunks
== 0)
1120 else if (zhdr
->middle_chunks
== 0)
1123 if (kref_put(&zhdr
->refcount
,
1124 release_z3fold_page_locked
))
1125 atomic64_dec(&pool
->pages_nr
);
1127 z3fold_page_unlock(zhdr
);
1128 pr_err("No free chunks in unbuddied\n");
1132 page
= virt_to_page(zhdr
);
1140 spin_lock(&pool
->stale_lock
);
1141 zhdr
= list_first_entry_or_null(&pool
->stale
,
1142 struct z3fold_header
, buddy
);
1144 * Before allocating a page, let's see if we can take one from
1145 * the stale pages list. cancel_work_sync() can sleep so we
1146 * limit this case to the contexts where we can sleep
1149 list_del(&zhdr
->buddy
);
1150 spin_unlock(&pool
->stale_lock
);
1151 cancel_work_sync(&zhdr
->work
);
1152 page
= virt_to_page(zhdr
);
1154 spin_unlock(&pool
->stale_lock
);
1158 page
= alloc_page(gfp
);
1163 zhdr
= init_z3fold_page(page
, bud
== HEADLESS
, pool
, gfp
);
1168 atomic64_inc(&pool
->pages_nr
);
1170 if (bud
== HEADLESS
) {
1171 set_bit(PAGE_HEADLESS
, &page
->private);
1176 __SetPageMovable(page
, pool
->inode
->i_mapping
);
1179 if (trylock_page(page
)) {
1180 __SetPageMovable(page
, pool
->inode
->i_mapping
);
1184 z3fold_page_lock(zhdr
);
1188 zhdr
->first_chunks
= chunks
;
1189 else if (bud
== LAST
)
1190 zhdr
->last_chunks
= chunks
;
1192 zhdr
->middle_chunks
= chunks
;
1193 zhdr
->start_middle
= zhdr
->first_chunks
+ ZHDR_CHUNKS
;
1195 add_to_unbuddied(pool
, zhdr
);
1198 spin_lock(&pool
->lock
);
1199 /* Add/move z3fold page to beginning of LRU */
1200 if (!list_empty(&page
->lru
))
1201 list_del(&page
->lru
);
1203 list_add(&page
->lru
, &pool
->lru
);
1205 *handle
= encode_handle(zhdr
, bud
);
1206 spin_unlock(&pool
->lock
);
1207 if (bud
!= HEADLESS
)
1208 z3fold_page_unlock(zhdr
);
1214 * z3fold_free() - frees the allocation associated with the given handle
1215 * @pool: pool in which the allocation resided
1216 * @handle: handle associated with the allocation returned by z3fold_alloc()
1218 * In the case that the z3fold page in which the allocation resides is under
1219 * reclaim, as indicated by the PG_reclaim flag being set, this function
1220 * only sets the first|last_chunks to 0. The page is actually freed
1221 * once both buddies are evicted (see z3fold_reclaim_page() below).
1223 static void z3fold_free(struct z3fold_pool
*pool
, unsigned long handle
)
1225 struct z3fold_header
*zhdr
;
1230 zhdr
= get_z3fold_header(handle
);
1231 page
= virt_to_page(zhdr
);
1232 page_claimed
= test_and_set_bit(PAGE_CLAIMED
, &page
->private);
1234 if (test_bit(PAGE_HEADLESS
, &page
->private)) {
1235 /* if a headless page is under reclaim, just leave.
1236 * NB: we use test_and_set_bit for a reason: if the bit
1237 * has not been set before, we release this page
1238 * immediately so we don't care about its value any more.
1240 if (!page_claimed
) {
1241 spin_lock(&pool
->lock
);
1242 list_del(&page
->lru
);
1243 spin_unlock(&pool
->lock
);
1244 put_z3fold_header(zhdr
);
1245 free_z3fold_page(page
, true);
1246 atomic64_dec(&pool
->pages_nr
);
1251 /* Non-headless case */
1252 bud
= handle_to_buddy(handle
);
1256 zhdr
->first_chunks
= 0;
1259 zhdr
->middle_chunks
= 0;
1262 zhdr
->last_chunks
= 0;
1265 pr_err("%s: unknown bud %d\n", __func__
, bud
);
1267 put_z3fold_header(zhdr
);
1268 clear_bit(PAGE_CLAIMED
, &page
->private);
1273 free_handle(handle
);
1274 if (kref_put(&zhdr
->refcount
, release_z3fold_page_locked_list
)) {
1275 atomic64_dec(&pool
->pages_nr
);
1279 /* the page has not been claimed by us */
1280 z3fold_page_unlock(zhdr
);
1283 if (unlikely(PageIsolated(page
)) ||
1284 test_and_set_bit(NEEDS_COMPACTING
, &page
->private)) {
1285 put_z3fold_header(zhdr
);
1286 clear_bit(PAGE_CLAIMED
, &page
->private);
1289 if (zhdr
->cpu
< 0 || !cpu_online(zhdr
->cpu
)) {
1290 spin_lock(&pool
->lock
);
1291 list_del_init(&zhdr
->buddy
);
1292 spin_unlock(&pool
->lock
);
1294 kref_get(&zhdr
->refcount
);
1295 clear_bit(PAGE_CLAIMED
, &page
->private);
1296 do_compact_page(zhdr
, true);
1299 kref_get(&zhdr
->refcount
);
1300 clear_bit(PAGE_CLAIMED
, &page
->private);
1301 queue_work_on(zhdr
->cpu
, pool
->compact_wq
, &zhdr
->work
);
1302 put_z3fold_header(zhdr
);
1306 * z3fold_reclaim_page() - evicts allocations from a pool page and frees it
1307 * @pool: pool from which a page will attempt to be evicted
1308 * @retries: number of pages on the LRU list for which eviction will
1309 * be attempted before failing
1311 * z3fold reclaim is different from normal system reclaim in that it is done
1312 * from the bottom, up. This is because only the bottom layer, z3fold, has
1313 * information on how the allocations are organized within each z3fold page.
1314 * This has the potential to create interesting locking situations between
1315 * z3fold and the user, however.
1317 * To avoid these, this is how z3fold_reclaim_page() should be called:
1319 * The user detects a page should be reclaimed and calls z3fold_reclaim_page().
1320 * z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
1321 * call the user-defined eviction handler with the pool and handle as
1324 * If the handle can not be evicted, the eviction handler should return
1325 * non-zero. z3fold_reclaim_page() will add the z3fold page back to the
1326 * appropriate list and try the next z3fold page on the LRU up to
1327 * a user defined number of retries.
1329 * If the handle is successfully evicted, the eviction handler should
1330 * return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
1331 * contains logic to delay freeing the page if the page is under reclaim,
1332 * as indicated by the setting of the PG_reclaim flag on the underlying page.
1334 * If all buddies in the z3fold page are successfully evicted, then the
1335 * z3fold page can be freed.
1337 * Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
1338 * no pages to evict or an eviction handler is not registered, -EAGAIN if
1339 * the retry limit was hit.
1341 static int z3fold_reclaim_page(struct z3fold_pool
*pool
, unsigned int retries
)
1344 struct z3fold_header
*zhdr
= NULL
;
1345 struct page
*page
= NULL
;
1346 struct list_head
*pos
;
1347 unsigned long first_handle
= 0, middle_handle
= 0, last_handle
= 0;
1349 spin_lock(&pool
->lock
);
1350 if (!pool
->ops
|| !pool
->ops
->evict
|| retries
== 0) {
1351 spin_unlock(&pool
->lock
);
1354 for (i
= 0; i
< retries
; i
++) {
1355 if (list_empty(&pool
->lru
)) {
1356 spin_unlock(&pool
->lock
);
1359 list_for_each_prev(pos
, &pool
->lru
) {
1360 page
= list_entry(pos
, struct page
, lru
);
1362 /* this bit could have been set by free, in which case
1363 * we pass over to the next page in the pool.
1365 if (test_and_set_bit(PAGE_CLAIMED
, &page
->private)) {
1370 if (unlikely(PageIsolated(page
))) {
1371 clear_bit(PAGE_CLAIMED
, &page
->private);
1375 zhdr
= page_address(page
);
1376 if (test_bit(PAGE_HEADLESS
, &page
->private))
1379 if (!z3fold_page_trylock(zhdr
)) {
1380 clear_bit(PAGE_CLAIMED
, &page
->private);
1382 continue; /* can't evict at this point */
1384 if (zhdr
->foreign_handles
) {
1385 clear_bit(PAGE_CLAIMED
, &page
->private);
1386 z3fold_page_unlock(zhdr
);
1388 continue; /* can't evict such page */
1390 kref_get(&zhdr
->refcount
);
1391 list_del_init(&zhdr
->buddy
);
1399 list_del_init(&page
->lru
);
1400 spin_unlock(&pool
->lock
);
1402 if (!test_bit(PAGE_HEADLESS
, &page
->private)) {
1404 * We need encode the handles before unlocking, and
1405 * use our local slots structure because z3fold_free
1406 * can zero out zhdr->slots and we can't do much
1412 if (zhdr
->first_chunks
)
1413 first_handle
= encode_handle(zhdr
, FIRST
);
1414 if (zhdr
->middle_chunks
)
1415 middle_handle
= encode_handle(zhdr
, MIDDLE
);
1416 if (zhdr
->last_chunks
)
1417 last_handle
= encode_handle(zhdr
, LAST
);
1419 * it's safe to unlock here because we hold a
1420 * reference to this page
1422 z3fold_page_unlock(zhdr
);
1424 first_handle
= encode_handle(zhdr
, HEADLESS
);
1425 last_handle
= middle_handle
= 0;
1427 /* Issue the eviction callback(s) */
1428 if (middle_handle
) {
1429 ret
= pool
->ops
->evict(pool
, middle_handle
);
1432 free_handle(middle_handle
);
1435 ret
= pool
->ops
->evict(pool
, first_handle
);
1438 free_handle(first_handle
);
1441 ret
= pool
->ops
->evict(pool
, last_handle
);
1444 free_handle(last_handle
);
1447 if (test_bit(PAGE_HEADLESS
, &page
->private)) {
1449 free_z3fold_page(page
, true);
1450 atomic64_dec(&pool
->pages_nr
);
1453 spin_lock(&pool
->lock
);
1454 list_add(&page
->lru
, &pool
->lru
);
1455 spin_unlock(&pool
->lock
);
1456 clear_bit(PAGE_CLAIMED
, &page
->private);
1458 z3fold_page_lock(zhdr
);
1459 if (kref_put(&zhdr
->refcount
,
1460 release_z3fold_page_locked
)) {
1461 atomic64_dec(&pool
->pages_nr
);
1465 * if we are here, the page is still not completely
1466 * free. Take the global pool lock then to be able
1467 * to add it back to the lru list
1469 spin_lock(&pool
->lock
);
1470 list_add(&page
->lru
, &pool
->lru
);
1471 spin_unlock(&pool
->lock
);
1472 z3fold_page_unlock(zhdr
);
1473 clear_bit(PAGE_CLAIMED
, &page
->private);
1476 /* We started off locked to we need to lock the pool back */
1477 spin_lock(&pool
->lock
);
1479 spin_unlock(&pool
->lock
);
1484 * z3fold_map() - maps the allocation associated with the given handle
1485 * @pool: pool in which the allocation resides
1486 * @handle: handle associated with the allocation to be mapped
1488 * Extracts the buddy number from handle and constructs the pointer to the
1489 * correct starting chunk within the page.
1491 * Returns: a pointer to the mapped allocation
1493 static void *z3fold_map(struct z3fold_pool
*pool
, unsigned long handle
)
1495 struct z3fold_header
*zhdr
;
1500 zhdr
= get_z3fold_header(handle
);
1502 page
= virt_to_page(zhdr
);
1504 if (test_bit(PAGE_HEADLESS
, &page
->private))
1507 buddy
= handle_to_buddy(handle
);
1510 addr
+= ZHDR_SIZE_ALIGNED
;
1513 addr
+= zhdr
->start_middle
<< CHUNK_SHIFT
;
1514 set_bit(MIDDLE_CHUNK_MAPPED
, &page
->private);
1517 addr
+= PAGE_SIZE
- (handle_to_chunks(handle
) << CHUNK_SHIFT
);
1520 pr_err("unknown buddy id %d\n", buddy
);
1527 zhdr
->mapped_count
++;
1529 put_z3fold_header(zhdr
);
1534 * z3fold_unmap() - unmaps the allocation associated with the given handle
1535 * @pool: pool in which the allocation resides
1536 * @handle: handle associated with the allocation to be unmapped
1538 static void z3fold_unmap(struct z3fold_pool
*pool
, unsigned long handle
)
1540 struct z3fold_header
*zhdr
;
1544 zhdr
= get_z3fold_header(handle
);
1545 page
= virt_to_page(zhdr
);
1547 if (test_bit(PAGE_HEADLESS
, &page
->private))
1550 buddy
= handle_to_buddy(handle
);
1551 if (buddy
== MIDDLE
)
1552 clear_bit(MIDDLE_CHUNK_MAPPED
, &page
->private);
1553 zhdr
->mapped_count
--;
1554 put_z3fold_header(zhdr
);
1558 * z3fold_get_pool_size() - gets the z3fold pool size in pages
1559 * @pool: pool whose size is being queried
1561 * Returns: size in pages of the given pool.
1563 static u64
z3fold_get_pool_size(struct z3fold_pool
*pool
)
1565 return atomic64_read(&pool
->pages_nr
);
1568 static bool z3fold_page_isolate(struct page
*page
, isolate_mode_t mode
)
1570 struct z3fold_header
*zhdr
;
1571 struct z3fold_pool
*pool
;
1573 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
1574 VM_BUG_ON_PAGE(PageIsolated(page
), page
);
1576 if (test_bit(PAGE_HEADLESS
, &page
->private) ||
1577 test_bit(PAGE_CLAIMED
, &page
->private))
1580 zhdr
= page_address(page
);
1581 z3fold_page_lock(zhdr
);
1582 if (test_bit(NEEDS_COMPACTING
, &page
->private) ||
1583 test_bit(PAGE_STALE
, &page
->private))
1586 if (zhdr
->mapped_count
!= 0 || zhdr
->foreign_handles
!= 0)
1589 pool
= zhdr_to_pool(zhdr
);
1590 spin_lock(&pool
->lock
);
1591 if (!list_empty(&zhdr
->buddy
))
1592 list_del_init(&zhdr
->buddy
);
1593 if (!list_empty(&page
->lru
))
1594 list_del_init(&page
->lru
);
1595 spin_unlock(&pool
->lock
);
1597 kref_get(&zhdr
->refcount
);
1598 z3fold_page_unlock(zhdr
);
1602 z3fold_page_unlock(zhdr
);
1606 static int z3fold_page_migrate(struct address_space
*mapping
, struct page
*newpage
,
1607 struct page
*page
, enum migrate_mode mode
)
1609 struct z3fold_header
*zhdr
, *new_zhdr
;
1610 struct z3fold_pool
*pool
;
1611 struct address_space
*new_mapping
;
1613 VM_BUG_ON_PAGE(!PageMovable(page
), page
);
1614 VM_BUG_ON_PAGE(!PageIsolated(page
), page
);
1615 VM_BUG_ON_PAGE(!PageLocked(newpage
), newpage
);
1617 zhdr
= page_address(page
);
1618 pool
= zhdr_to_pool(zhdr
);
1620 if (!z3fold_page_trylock(zhdr
)) {
1623 if (zhdr
->mapped_count
!= 0 || zhdr
->foreign_handles
!= 0) {
1624 z3fold_page_unlock(zhdr
);
1627 if (work_pending(&zhdr
->work
)) {
1628 z3fold_page_unlock(zhdr
);
1631 new_zhdr
= page_address(newpage
);
1632 memcpy(new_zhdr
, zhdr
, PAGE_SIZE
);
1633 newpage
->private = page
->private;
1635 z3fold_page_unlock(zhdr
);
1636 spin_lock_init(&new_zhdr
->page_lock
);
1637 INIT_WORK(&new_zhdr
->work
, compact_page_work
);
1639 * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
1640 * so we only have to reinitialize it.
1642 INIT_LIST_HEAD(&new_zhdr
->buddy
);
1643 new_mapping
= page_mapping(page
);
1644 __ClearPageMovable(page
);
1645 ClearPagePrivate(page
);
1648 z3fold_page_lock(new_zhdr
);
1649 if (new_zhdr
->first_chunks
)
1650 encode_handle(new_zhdr
, FIRST
);
1651 if (new_zhdr
->last_chunks
)
1652 encode_handle(new_zhdr
, LAST
);
1653 if (new_zhdr
->middle_chunks
)
1654 encode_handle(new_zhdr
, MIDDLE
);
1655 set_bit(NEEDS_COMPACTING
, &newpage
->private);
1656 new_zhdr
->cpu
= smp_processor_id();
1657 spin_lock(&pool
->lock
);
1658 list_add(&newpage
->lru
, &pool
->lru
);
1659 spin_unlock(&pool
->lock
);
1660 __SetPageMovable(newpage
, new_mapping
);
1661 z3fold_page_unlock(new_zhdr
);
1663 queue_work_on(new_zhdr
->cpu
, pool
->compact_wq
, &new_zhdr
->work
);
1665 page_mapcount_reset(page
);
1670 static void z3fold_page_putback(struct page
*page
)
1672 struct z3fold_header
*zhdr
;
1673 struct z3fold_pool
*pool
;
1675 zhdr
= page_address(page
);
1676 pool
= zhdr_to_pool(zhdr
);
1678 z3fold_page_lock(zhdr
);
1679 if (!list_empty(&zhdr
->buddy
))
1680 list_del_init(&zhdr
->buddy
);
1681 INIT_LIST_HEAD(&page
->lru
);
1682 if (kref_put(&zhdr
->refcount
, release_z3fold_page_locked
)) {
1683 atomic64_dec(&pool
->pages_nr
);
1686 spin_lock(&pool
->lock
);
1687 list_add(&page
->lru
, &pool
->lru
);
1688 spin_unlock(&pool
->lock
);
1689 z3fold_page_unlock(zhdr
);
1692 static const struct address_space_operations z3fold_aops
= {
1693 .isolate_page
= z3fold_page_isolate
,
1694 .migratepage
= z3fold_page_migrate
,
1695 .putback_page
= z3fold_page_putback
,
1702 static int z3fold_zpool_evict(struct z3fold_pool
*pool
, unsigned long handle
)
1704 if (pool
->zpool
&& pool
->zpool_ops
&& pool
->zpool_ops
->evict
)
1705 return pool
->zpool_ops
->evict(pool
->zpool
, handle
);
1710 static const struct z3fold_ops z3fold_zpool_ops
= {
1711 .evict
= z3fold_zpool_evict
1714 static void *z3fold_zpool_create(const char *name
, gfp_t gfp
,
1715 const struct zpool_ops
*zpool_ops
,
1716 struct zpool
*zpool
)
1718 struct z3fold_pool
*pool
;
1720 pool
= z3fold_create_pool(name
, gfp
,
1721 zpool_ops
? &z3fold_zpool_ops
: NULL
);
1723 pool
->zpool
= zpool
;
1724 pool
->zpool_ops
= zpool_ops
;
1729 static void z3fold_zpool_destroy(void *pool
)
1731 z3fold_destroy_pool(pool
);
1734 static int z3fold_zpool_malloc(void *pool
, size_t size
, gfp_t gfp
,
1735 unsigned long *handle
)
1737 return z3fold_alloc(pool
, size
, gfp
, handle
);
1739 static void z3fold_zpool_free(void *pool
, unsigned long handle
)
1741 z3fold_free(pool
, handle
);
1744 static int z3fold_zpool_shrink(void *pool
, unsigned int pages
,
1745 unsigned int *reclaimed
)
1747 unsigned int total
= 0;
1750 while (total
< pages
) {
1751 ret
= z3fold_reclaim_page(pool
, 8);
1763 static void *z3fold_zpool_map(void *pool
, unsigned long handle
,
1764 enum zpool_mapmode mm
)
1766 return z3fold_map(pool
, handle
);
1768 static void z3fold_zpool_unmap(void *pool
, unsigned long handle
)
1770 z3fold_unmap(pool
, handle
);
1773 static u64
z3fold_zpool_total_size(void *pool
)
1775 return z3fold_get_pool_size(pool
) * PAGE_SIZE
;
1778 static struct zpool_driver z3fold_zpool_driver
= {
1780 .owner
= THIS_MODULE
,
1781 .create
= z3fold_zpool_create
,
1782 .destroy
= z3fold_zpool_destroy
,
1783 .malloc
= z3fold_zpool_malloc
,
1784 .free
= z3fold_zpool_free
,
1785 .shrink
= z3fold_zpool_shrink
,
1786 .map
= z3fold_zpool_map
,
1787 .unmap
= z3fold_zpool_unmap
,
1788 .total_size
= z3fold_zpool_total_size
,
1791 MODULE_ALIAS("zpool-z3fold");
1793 static int __init
init_z3fold(void)
1797 /* Make sure the z3fold header is not larger than the page size */
1798 BUILD_BUG_ON(ZHDR_SIZE_ALIGNED
> PAGE_SIZE
);
1799 ret
= z3fold_mount();
1803 zpool_register_driver(&z3fold_zpool_driver
);
1808 static void __exit
exit_z3fold(void)
1811 zpool_unregister_driver(&z3fold_zpool_driver
);
1814 module_init(init_z3fold
);
1815 module_exit(exit_z3fold
);
1817 MODULE_LICENSE("GPL");
1818 MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
1819 MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");