+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * z3fold.c
- *
- * Author: Vitaly Wool <vitaly.wool@konsulko.com>
- * Copyright (C) 2016, Sony Mobile Communications Inc.
- *
- * This implementation is based on zbud written by Seth Jennings.
- *
- * z3fold is an special purpose allocator for storing compressed pages. It
- * can store up to three compressed pages per page which improves the
- * compression ratio of zbud while retaining its main concepts (e. g. always
- * storing an integral number of objects per page) and simplicity.
- * It still has simple and deterministic reclaim properties that make it
- * preferable to a higher density approach (with no requirement on integral
- * number of object per page) when reclaim is used.
- *
- * As in zbud, pages are divided into "chunks". The size of the chunks is
- * fixed at compile time and is determined by NCHUNKS_ORDER below.
- *
- * z3fold doesn't export any API and is meant to be used via zpool API.
- */
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/atomic.h>
-#include <linux/sched.h>
-#include <linux/cpumask.h>
-#include <linux/list.h>
-#include <linux/mm.h>
-#include <linux/module.h>
-#include <linux/page-flags.h>
-#include <linux/migrate.h>
-#include <linux/node.h>
-#include <linux/compaction.h>
-#include <linux/percpu.h>
-#include <linux/preempt.h>
-#include <linux/workqueue.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/zpool.h>
-#include <linux/kmemleak.h>
-
-/*
- * NCHUNKS_ORDER determines the internal allocation granularity, effectively
- * adjusting internal fragmentation. It also determines the number of
- * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
- * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
- * in the beginning of an allocated page are occupied by z3fold header, so
- * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
- * which shows the max number of free chunks in z3fold page, also there will
- * be 63, or 62, respectively, freelists per pool.
- */
-#define NCHUNKS_ORDER 6
-
-#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
-#define CHUNK_SIZE (1 << CHUNK_SHIFT)
-#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
-#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
-#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
-#define NCHUNKS (TOTAL_CHUNKS - ZHDR_CHUNKS)
-
-#define BUDDY_MASK (0x3)
-#define BUDDY_SHIFT 2
-#define SLOTS_ALIGN (0x40)
-
-/*****************
- * Structures
-*****************/
-struct z3fold_pool;
-
-enum buddy {
- HEADLESS = 0,
- FIRST,
- MIDDLE,
- LAST,
- BUDDIES_MAX = LAST
-};
-
-struct z3fold_buddy_slots {
- /*
- * we are using BUDDY_MASK in handle_to_buddy etc. so there should
- * be enough slots to hold all possible variants
- */
- unsigned long slot[BUDDY_MASK + 1];
- unsigned long pool; /* back link */
- rwlock_t lock;
-};
-#define HANDLE_FLAG_MASK (0x03)
-
-/*
- * struct z3fold_header - z3fold page metadata occupying first chunks of each
- * z3fold page, except for HEADLESS pages
- * @buddy: links the z3fold page into the relevant list in the
- * pool
- * @page_lock: per-page lock
- * @refcount: reference count for the z3fold page
- * @work: work_struct for page layout optimization
- * @slots: pointer to the structure holding buddy slots
- * @pool: pointer to the containing pool
- * @cpu: CPU which this page "belongs" to
- * @first_chunks: the size of the first buddy in chunks, 0 if free
- * @middle_chunks: the size of the middle buddy in chunks, 0 if free
- * @last_chunks: the size of the last buddy in chunks, 0 if free
- * @first_num: the starting number (for the first handle)
- * @mapped_count: the number of objects currently mapped
- */
-struct z3fold_header {
- struct list_head buddy;
- spinlock_t page_lock;
- struct kref refcount;
- struct work_struct work;
- struct z3fold_buddy_slots *slots;
- struct z3fold_pool *pool;
- short cpu;
- unsigned short first_chunks;
- unsigned short middle_chunks;
- unsigned short last_chunks;
- unsigned short start_middle;
- unsigned short first_num:2;
- unsigned short mapped_count:2;
- unsigned short foreign_handles:2;
-};
-
-/**
- * struct z3fold_pool - stores metadata for each z3fold pool
- * @name: pool name
- * @lock: protects pool unbuddied lists
- * @stale_lock: protects pool stale page list
- * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
- * buddies; the list each z3fold page is added to depends on
- * the size of its free region.
- * @stale: list of pages marked for freeing
- * @pages_nr: number of z3fold pages in the pool.
- * @c_handle: cache for z3fold_buddy_slots allocation
- * @compact_wq: workqueue for page layout background optimization
- * @release_wq: workqueue for safe page release
- * @work: work_struct for safe page release
- *
- * This structure is allocated at pool creation time and maintains metadata
- * pertaining to a particular z3fold pool.
- */
-struct z3fold_pool {
- const char *name;
- spinlock_t lock;
- spinlock_t stale_lock;
- struct list_head __percpu *unbuddied;
- struct list_head stale;
- atomic64_t pages_nr;
- struct kmem_cache *c_handle;
- struct workqueue_struct *compact_wq;
- struct workqueue_struct *release_wq;
- struct work_struct work;
-};
-
-/*
- * Internal z3fold page flags
- */
-enum z3fold_page_flags {
- PAGE_HEADLESS = 0,
- MIDDLE_CHUNK_MAPPED,
- NEEDS_COMPACTING,
- PAGE_STALE,
- PAGE_CLAIMED, /* by either reclaim or free */
- PAGE_MIGRATED, /* page is migrated and soon to be released */
-};
-
-/*
- * handle flags, go under HANDLE_FLAG_MASK
- */
-enum z3fold_handle_flags {
- HANDLES_NOFREE = 0,
-};
-
-/*
- * Forward declarations
- */
-static struct z3fold_header *__z3fold_alloc(struct z3fold_pool *, size_t, bool);
-static void compact_page_work(struct work_struct *w);
-
-/*****************
- * Helpers
-*****************/
-
-/* Converts an allocation size in bytes to size in z3fold chunks */
-static int size_to_chunks(size_t size)
-{
- return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
-}
-
-#define for_each_unbuddied_list(_iter, _begin) \
- for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
-
-static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
- gfp_t gfp)
-{
- struct z3fold_buddy_slots *slots = kmem_cache_zalloc(pool->c_handle,
- gfp);
-
- if (slots) {
- /* It will be freed separately in free_handle(). */
- kmemleak_not_leak(slots);
- slots->pool = (unsigned long)pool;
- rwlock_init(&slots->lock);
- }
-
- return slots;
-}
-
-static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s)
-{
- return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK);
-}
-
-static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle)
-{
- return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1));
-}
-
-/* Lock a z3fold page */
-static inline void z3fold_page_lock(struct z3fold_header *zhdr)
-{
- spin_lock(&zhdr->page_lock);
-}
-
-/* Try to lock a z3fold page */
-static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
-{
- return spin_trylock(&zhdr->page_lock);
-}
-
-/* Unlock a z3fold page */
-static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
-{
- spin_unlock(&zhdr->page_lock);
-}
-
-/* return locked z3fold page if it's not headless */
-static inline struct z3fold_header *get_z3fold_header(unsigned long handle)
-{
- struct z3fold_buddy_slots *slots;
- struct z3fold_header *zhdr;
- int locked = 0;
-
- if (!(handle & (1 << PAGE_HEADLESS))) {
- slots = handle_to_slots(handle);
- do {
- unsigned long addr;
-
- read_lock(&slots->lock);
- addr = *(unsigned long *)handle;
- zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
- locked = z3fold_page_trylock(zhdr);
- read_unlock(&slots->lock);
- if (locked) {
- struct page *page = virt_to_page(zhdr);
-
- if (!test_bit(PAGE_MIGRATED, &page->private))
- break;
- z3fold_page_unlock(zhdr);
- }
- cpu_relax();
- } while (true);
- } else {
- zhdr = (struct z3fold_header *)(handle & PAGE_MASK);
- }
-
- return zhdr;
-}
-
-static inline void put_z3fold_header(struct z3fold_header *zhdr)
-{
- struct page *page = virt_to_page(zhdr);
-
- if (!test_bit(PAGE_HEADLESS, &page->private))
- z3fold_page_unlock(zhdr);
-}
-
-static inline void free_handle(unsigned long handle, struct z3fold_header *zhdr)
-{
- struct z3fold_buddy_slots *slots;
- int i;
- bool is_free;
-
- if (WARN_ON(*(unsigned long *)handle == 0))
- return;
-
- slots = handle_to_slots(handle);
- write_lock(&slots->lock);
- *(unsigned long *)handle = 0;
-
- if (test_bit(HANDLES_NOFREE, &slots->pool)) {
- write_unlock(&slots->lock);
- return; /* simple case, nothing else to do */
- }
-
- if (zhdr->slots != slots)
- zhdr->foreign_handles--;
-
- is_free = true;
- for (i = 0; i <= BUDDY_MASK; i++) {
- if (slots->slot[i]) {
- is_free = false;
- break;
- }
- }
- write_unlock(&slots->lock);
-
- if (is_free) {
- struct z3fold_pool *pool = slots_to_pool(slots);
-
- if (zhdr->slots == slots)
- zhdr->slots = NULL;
- kmem_cache_free(pool->c_handle, slots);
- }
-}
-
-/* Initializes the z3fold header of a newly allocated z3fold page */
-static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
- struct z3fold_pool *pool, gfp_t gfp)
-{
- struct z3fold_header *zhdr = page_address(page);
- struct z3fold_buddy_slots *slots;
-
- clear_bit(PAGE_HEADLESS, &page->private);
- clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
- clear_bit(NEEDS_COMPACTING, &page->private);
- clear_bit(PAGE_STALE, &page->private);
- clear_bit(PAGE_CLAIMED, &page->private);
- clear_bit(PAGE_MIGRATED, &page->private);
- if (headless)
- return zhdr;
-
- slots = alloc_slots(pool, gfp);
- if (!slots)
- return NULL;
-
- memset(zhdr, 0, sizeof(*zhdr));
- spin_lock_init(&zhdr->page_lock);
- kref_init(&zhdr->refcount);
- zhdr->cpu = -1;
- zhdr->slots = slots;
- zhdr->pool = pool;
- INIT_LIST_HEAD(&zhdr->buddy);
- INIT_WORK(&zhdr->work, compact_page_work);
- return zhdr;
-}
-
-/* Resets the struct page fields and frees the page */
-static void free_z3fold_page(struct page *page, bool headless)
-{
- if (!headless) {
- lock_page(page);
- __ClearPageMovable(page);
- unlock_page(page);
- }
- __free_page(page);
-}
-
-/* Helper function to build the index */
-static inline int __idx(struct z3fold_header *zhdr, enum buddy bud)
-{
- return (bud + zhdr->first_num) & BUDDY_MASK;
-}
-
-/*
- * Encodes the handle of a particular buddy within a z3fold page.
- * Zhdr->page_lock should be held as this function accesses first_num
- * if bud != HEADLESS.
- */
-static unsigned long __encode_handle(struct z3fold_header *zhdr,
- struct z3fold_buddy_slots *slots,
- enum buddy bud)
-{
- unsigned long h = (unsigned long)zhdr;
- int idx = 0;
-
- /*
- * For a headless page, its handle is its pointer with the extra
- * PAGE_HEADLESS bit set
- */
- if (bud == HEADLESS)
- return h | (1 << PAGE_HEADLESS);
-
- /* otherwise, return pointer to encoded handle */
- idx = __idx(zhdr, bud);
- h += idx;
- if (bud == LAST)
- h |= (zhdr->last_chunks << BUDDY_SHIFT);
-
- write_lock(&slots->lock);
- slots->slot[idx] = h;
- write_unlock(&slots->lock);
- return (unsigned long)&slots->slot[idx];
-}
-
-static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
-{
- return __encode_handle(zhdr, zhdr->slots, bud);
-}
-
-/* only for LAST bud, returns zero otherwise */
-static unsigned short handle_to_chunks(unsigned long handle)
-{
- struct z3fold_buddy_slots *slots = handle_to_slots(handle);
- unsigned long addr;
-
- read_lock(&slots->lock);
- addr = *(unsigned long *)handle;
- read_unlock(&slots->lock);
- return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
-}
-
-/*
- * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
- * but that doesn't matter. because the masking will result in the
- * correct buddy number.
- */
-static enum buddy handle_to_buddy(unsigned long handle)
-{
- struct z3fold_header *zhdr;
- struct z3fold_buddy_slots *slots = handle_to_slots(handle);
- unsigned long addr;
-
- read_lock(&slots->lock);
- WARN_ON(handle & (1 << PAGE_HEADLESS));
- addr = *(unsigned long *)handle;
- read_unlock(&slots->lock);
- zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
- return (addr - zhdr->first_num) & BUDDY_MASK;
-}
-
-static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr)
-{
- return zhdr->pool;
-}
-
-static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
-{
- struct page *page = virt_to_page(zhdr);
- struct z3fold_pool *pool = zhdr_to_pool(zhdr);
-
- WARN_ON(!list_empty(&zhdr->buddy));
- set_bit(PAGE_STALE, &page->private);
- clear_bit(NEEDS_COMPACTING, &page->private);
- spin_lock(&pool->lock);
- spin_unlock(&pool->lock);
-
- if (locked)
- z3fold_page_unlock(zhdr);
-
- spin_lock(&pool->stale_lock);
- list_add(&zhdr->buddy, &pool->stale);
- queue_work(pool->release_wq, &pool->work);
- spin_unlock(&pool->stale_lock);
-
- atomic64_dec(&pool->pages_nr);
-}
-
-static void release_z3fold_page_locked(struct kref *ref)
-{
- struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
- refcount);
- WARN_ON(z3fold_page_trylock(zhdr));
- __release_z3fold_page(zhdr, true);
-}
-
-static void release_z3fold_page_locked_list(struct kref *ref)
-{
- struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
- refcount);
- struct z3fold_pool *pool = zhdr_to_pool(zhdr);
-
- spin_lock(&pool->lock);
- list_del_init(&zhdr->buddy);
- spin_unlock(&pool->lock);
-
- WARN_ON(z3fold_page_trylock(zhdr));
- __release_z3fold_page(zhdr, true);
-}
-
-static inline int put_z3fold_locked(struct z3fold_header *zhdr)
-{
- return kref_put(&zhdr->refcount, release_z3fold_page_locked);
-}
-
-static inline int put_z3fold_locked_list(struct z3fold_header *zhdr)
-{
- return kref_put(&zhdr->refcount, release_z3fold_page_locked_list);
-}
-
-static void free_pages_work(struct work_struct *w)
-{
- struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work);
-
- spin_lock(&pool->stale_lock);
- while (!list_empty(&pool->stale)) {
- struct z3fold_header *zhdr = list_first_entry(&pool->stale,
- struct z3fold_header, buddy);
- struct page *page = virt_to_page(zhdr);
-
- list_del(&zhdr->buddy);
- if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
- continue;
- spin_unlock(&pool->stale_lock);
- cancel_work_sync(&zhdr->work);
- free_z3fold_page(page, false);
- cond_resched();
- spin_lock(&pool->stale_lock);
- }
- spin_unlock(&pool->stale_lock);
-}
-
-/*
- * Returns the number of free chunks in a z3fold page.
- * NB: can't be used with HEADLESS pages.
- */
-static int num_free_chunks(struct z3fold_header *zhdr)
-{
- int nfree;
- /*
- * If there is a middle object, pick up the bigger free space
- * either before or after it. Otherwise just subtract the number
- * of chunks occupied by the first and the last objects.
- */
- if (zhdr->middle_chunks != 0) {
- int nfree_before = zhdr->first_chunks ?
- 0 : zhdr->start_middle - ZHDR_CHUNKS;
- int nfree_after = zhdr->last_chunks ?
- 0 : TOTAL_CHUNKS -
- (zhdr->start_middle + zhdr->middle_chunks);
- nfree = max(nfree_before, nfree_after);
- } else
- nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
- return nfree;
-}
-
-/* Add to the appropriate unbuddied list */
-static inline void add_to_unbuddied(struct z3fold_pool *pool,
- struct z3fold_header *zhdr)
-{
- if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
- zhdr->middle_chunks == 0) {
- struct list_head *unbuddied;
- int freechunks = num_free_chunks(zhdr);
-
- migrate_disable();
- unbuddied = this_cpu_ptr(pool->unbuddied);
- spin_lock(&pool->lock);
- list_add(&zhdr->buddy, &unbuddied[freechunks]);
- spin_unlock(&pool->lock);
- zhdr->cpu = smp_processor_id();
- migrate_enable();
- }
-}
-
-static inline enum buddy get_free_buddy(struct z3fold_header *zhdr, int chunks)
-{
- enum buddy bud = HEADLESS;
-
- if (zhdr->middle_chunks) {
- if (!zhdr->first_chunks &&
- chunks <= zhdr->start_middle - ZHDR_CHUNKS)
- bud = FIRST;
- else if (!zhdr->last_chunks)
- bud = LAST;
- } else {
- if (!zhdr->first_chunks)
- bud = FIRST;
- else if (!zhdr->last_chunks)
- bud = LAST;
- else
- bud = MIDDLE;
- }
-
- return bud;
-}
-
-static inline void *mchunk_memmove(struct z3fold_header *zhdr,
- unsigned short dst_chunk)
-{
- void *beg = zhdr;
- return memmove(beg + (dst_chunk << CHUNK_SHIFT),
- beg + (zhdr->start_middle << CHUNK_SHIFT),
- zhdr->middle_chunks << CHUNK_SHIFT);
-}
-
-static inline bool buddy_single(struct z3fold_header *zhdr)
-{
- return !((zhdr->first_chunks && zhdr->middle_chunks) ||
- (zhdr->first_chunks && zhdr->last_chunks) ||
- (zhdr->middle_chunks && zhdr->last_chunks));
-}
-
-static struct z3fold_header *compact_single_buddy(struct z3fold_header *zhdr)
-{
- struct z3fold_pool *pool = zhdr_to_pool(zhdr);
- void *p = zhdr;
- unsigned long old_handle = 0;
- size_t sz = 0;
- struct z3fold_header *new_zhdr = NULL;
- int first_idx = __idx(zhdr, FIRST);
- int middle_idx = __idx(zhdr, MIDDLE);
- int last_idx = __idx(zhdr, LAST);
- unsigned short *moved_chunks = NULL;
-
- /*
- * No need to protect slots here -- all the slots are "local" and
- * the page lock is already taken
- */
- if (zhdr->first_chunks && zhdr->slots->slot[first_idx]) {
- p += ZHDR_SIZE_ALIGNED;
- sz = zhdr->first_chunks << CHUNK_SHIFT;
- old_handle = (unsigned long)&zhdr->slots->slot[first_idx];
- moved_chunks = &zhdr->first_chunks;
- } else if (zhdr->middle_chunks && zhdr->slots->slot[middle_idx]) {
- p += zhdr->start_middle << CHUNK_SHIFT;
- sz = zhdr->middle_chunks << CHUNK_SHIFT;
- old_handle = (unsigned long)&zhdr->slots->slot[middle_idx];
- moved_chunks = &zhdr->middle_chunks;
- } else if (zhdr->last_chunks && zhdr->slots->slot[last_idx]) {
- p += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
- sz = zhdr->last_chunks << CHUNK_SHIFT;
- old_handle = (unsigned long)&zhdr->slots->slot[last_idx];
- moved_chunks = &zhdr->last_chunks;
- }
-
- if (sz > 0) {
- enum buddy new_bud = HEADLESS;
- short chunks = size_to_chunks(sz);
- void *q;
-
- new_zhdr = __z3fold_alloc(pool, sz, false);
- if (!new_zhdr)
- return NULL;
-
- if (WARN_ON(new_zhdr == zhdr))
- goto out_fail;
-
- new_bud = get_free_buddy(new_zhdr, chunks);
- q = new_zhdr;
- switch (new_bud) {
- case FIRST:
- new_zhdr->first_chunks = chunks;
- q += ZHDR_SIZE_ALIGNED;
- break;
- case MIDDLE:
- new_zhdr->middle_chunks = chunks;
- new_zhdr->start_middle =
- new_zhdr->first_chunks + ZHDR_CHUNKS;
- q += new_zhdr->start_middle << CHUNK_SHIFT;
- break;
- case LAST:
- new_zhdr->last_chunks = chunks;
- q += PAGE_SIZE - (new_zhdr->last_chunks << CHUNK_SHIFT);
- break;
- default:
- goto out_fail;
- }
- new_zhdr->foreign_handles++;
- memcpy(q, p, sz);
- write_lock(&zhdr->slots->lock);
- *(unsigned long *)old_handle = (unsigned long)new_zhdr +
- __idx(new_zhdr, new_bud);
- if (new_bud == LAST)
- *(unsigned long *)old_handle |=
- (new_zhdr->last_chunks << BUDDY_SHIFT);
- write_unlock(&zhdr->slots->lock);
- add_to_unbuddied(pool, new_zhdr);
- z3fold_page_unlock(new_zhdr);
-
- *moved_chunks = 0;
- }
-
- return new_zhdr;
-
-out_fail:
- if (new_zhdr && !put_z3fold_locked(new_zhdr)) {
- add_to_unbuddied(pool, new_zhdr);
- z3fold_page_unlock(new_zhdr);
- }
- return NULL;
-
-}
-
-#define BIG_CHUNK_GAP 3
-/* Has to be called with lock held */
-static int z3fold_compact_page(struct z3fold_header *zhdr)
-{
- struct page *page = virt_to_page(zhdr);
-
- if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
- return 0; /* can't move middle chunk, it's used */
-
- if (unlikely(PageIsolated(page)))
- return 0;
-
- if (zhdr->middle_chunks == 0)
- return 0; /* nothing to compact */
-
- if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
- /* move to the beginning */
- mchunk_memmove(zhdr, ZHDR_CHUNKS);
- zhdr->first_chunks = zhdr->middle_chunks;
- zhdr->middle_chunks = 0;
- zhdr->start_middle = 0;
- zhdr->first_num++;
- return 1;
- }
-
- /*
- * moving data is expensive, so let's only do that if
- * there's substantial gain (at least BIG_CHUNK_GAP chunks)
- */
- if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
- zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
- BIG_CHUNK_GAP) {
- mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
- zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
- return 1;
- } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
- TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
- + zhdr->middle_chunks) >=
- BIG_CHUNK_GAP) {
- unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
- zhdr->middle_chunks;
- mchunk_memmove(zhdr, new_start);
- zhdr->start_middle = new_start;
- return 1;
- }
-
- return 0;
-}
-
-static void do_compact_page(struct z3fold_header *zhdr, bool locked)
-{
- struct z3fold_pool *pool = zhdr_to_pool(zhdr);
- struct page *page;
-
- page = virt_to_page(zhdr);
- if (locked)
- WARN_ON(z3fold_page_trylock(zhdr));
- else
- z3fold_page_lock(zhdr);
- if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING, &page->private))) {
- z3fold_page_unlock(zhdr);
- return;
- }
- spin_lock(&pool->lock);
- list_del_init(&zhdr->buddy);
- spin_unlock(&pool->lock);
-
- if (put_z3fold_locked(zhdr))
- return;
-
- if (test_bit(PAGE_STALE, &page->private) ||
- test_and_set_bit(PAGE_CLAIMED, &page->private)) {
- z3fold_page_unlock(zhdr);
- return;
- }
-
- if (!zhdr->foreign_handles && buddy_single(zhdr) &&
- zhdr->mapped_count == 0 && compact_single_buddy(zhdr)) {
- if (!put_z3fold_locked(zhdr)) {
- clear_bit(PAGE_CLAIMED, &page->private);
- z3fold_page_unlock(zhdr);
- }
- return;
- }
-
- z3fold_compact_page(zhdr);
- add_to_unbuddied(pool, zhdr);
- clear_bit(PAGE_CLAIMED, &page->private);
- z3fold_page_unlock(zhdr);
-}
-
-static void compact_page_work(struct work_struct *w)
-{
- struct z3fold_header *zhdr = container_of(w, struct z3fold_header,
- work);
-
- do_compact_page(zhdr, false);
-}
-
-/* returns _locked_ z3fold page header or NULL */
-static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool,
- size_t size, bool can_sleep)
-{
- struct z3fold_header *zhdr = NULL;
- struct page *page;
- struct list_head *unbuddied;
- int chunks = size_to_chunks(size), i;
-
-lookup:
- migrate_disable();
- /* First, try to find an unbuddied z3fold page. */
- unbuddied = this_cpu_ptr(pool->unbuddied);
- for_each_unbuddied_list(i, chunks) {
- struct list_head *l = &unbuddied[i];
-
- zhdr = list_first_entry_or_null(READ_ONCE(l),
- struct z3fold_header, buddy);
-
- if (!zhdr)
- continue;
-
- /* Re-check under lock. */
- spin_lock(&pool->lock);
- if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
- struct z3fold_header, buddy)) ||
- !z3fold_page_trylock(zhdr)) {
- spin_unlock(&pool->lock);
- zhdr = NULL;
- migrate_enable();
- if (can_sleep)
- cond_resched();
- goto lookup;
- }
- list_del_init(&zhdr->buddy);
- zhdr->cpu = -1;
- spin_unlock(&pool->lock);
-
- page = virt_to_page(zhdr);
- if (test_bit(NEEDS_COMPACTING, &page->private) ||
- test_bit(PAGE_CLAIMED, &page->private)) {
- z3fold_page_unlock(zhdr);
- zhdr = NULL;
- migrate_enable();
- if (can_sleep)
- cond_resched();
- goto lookup;
- }
-
- /*
- * this page could not be removed from its unbuddied
- * list while pool lock was held, and then we've taken
- * page lock so kref_put could not be called before
- * we got here, so it's safe to just call kref_get()
- */
- kref_get(&zhdr->refcount);
- break;
- }
- migrate_enable();
-
- if (!zhdr) {
- int cpu;
-
- /* look for _exact_ match on other cpus' lists */
- for_each_online_cpu(cpu) {
- struct list_head *l;
-
- unbuddied = per_cpu_ptr(pool->unbuddied, cpu);
- spin_lock(&pool->lock);
- l = &unbuddied[chunks];
-
- zhdr = list_first_entry_or_null(READ_ONCE(l),
- struct z3fold_header, buddy);
-
- if (!zhdr || !z3fold_page_trylock(zhdr)) {
- spin_unlock(&pool->lock);
- zhdr = NULL;
- continue;
- }
- list_del_init(&zhdr->buddy);
- zhdr->cpu = -1;
- spin_unlock(&pool->lock);
-
- page = virt_to_page(zhdr);
- if (test_bit(NEEDS_COMPACTING, &page->private) ||
- test_bit(PAGE_CLAIMED, &page->private)) {
- z3fold_page_unlock(zhdr);
- zhdr = NULL;
- if (can_sleep)
- cond_resched();
- continue;
- }
- kref_get(&zhdr->refcount);
- break;
- }
- }
-
- if (zhdr && !zhdr->slots) {
- zhdr->slots = alloc_slots(pool, GFP_ATOMIC);
- if (!zhdr->slots)
- goto out_fail;
- }
- return zhdr;
-
-out_fail:
- if (!put_z3fold_locked(zhdr)) {
- add_to_unbuddied(pool, zhdr);
- z3fold_page_unlock(zhdr);
- }
- return NULL;
-}
-
-/*
- * API Functions
- */
-
-/**
- * z3fold_create_pool() - create a new z3fold pool
- * @name: pool name
- * @gfp: gfp flags when allocating the z3fold pool structure
- *
- * Return: pointer to the new z3fold pool or NULL if the metadata allocation
- * failed.
- */
-static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp)
-{
- struct z3fold_pool *pool = NULL;
- int i, cpu;
-
- pool = kzalloc(sizeof(struct z3fold_pool), gfp);
- if (!pool)
- goto out;
- pool->c_handle = kmem_cache_create("z3fold_handle",
- sizeof(struct z3fold_buddy_slots),
- SLOTS_ALIGN, 0, NULL);
- if (!pool->c_handle)
- goto out_c;
- spin_lock_init(&pool->lock);
- spin_lock_init(&pool->stale_lock);
- pool->unbuddied = __alloc_percpu(sizeof(struct list_head) * NCHUNKS,
- __alignof__(struct list_head));
- if (!pool->unbuddied)
- goto out_pool;
- for_each_possible_cpu(cpu) {
- struct list_head *unbuddied =
- per_cpu_ptr(pool->unbuddied, cpu);
- for_each_unbuddied_list(i, 0)
- INIT_LIST_HEAD(&unbuddied[i]);
- }
- INIT_LIST_HEAD(&pool->stale);
- atomic64_set(&pool->pages_nr, 0);
- pool->name = name;
- pool->compact_wq = create_singlethread_workqueue(pool->name);
- if (!pool->compact_wq)
- goto out_unbuddied;
- pool->release_wq = create_singlethread_workqueue(pool->name);
- if (!pool->release_wq)
- goto out_wq;
- INIT_WORK(&pool->work, free_pages_work);
- return pool;
-
-out_wq:
- destroy_workqueue(pool->compact_wq);
-out_unbuddied:
- free_percpu(pool->unbuddied);
-out_pool:
- kmem_cache_destroy(pool->c_handle);
-out_c:
- kfree(pool);
-out:
- return NULL;
-}
-
-/**
- * z3fold_destroy_pool() - destroys an existing z3fold pool
- * @pool: the z3fold pool to be destroyed
- *
- * The pool should be emptied before this function is called.
- */
-static void z3fold_destroy_pool(struct z3fold_pool *pool)
-{
- kmem_cache_destroy(pool->c_handle);
-
- /*
- * We need to destroy pool->compact_wq before pool->release_wq,
- * as any pending work on pool->compact_wq will call
- * queue_work(pool->release_wq, &pool->work).
- *
- * There are still outstanding pages until both workqueues are drained,
- * so we cannot unregister migration until then.
- */
-
- destroy_workqueue(pool->compact_wq);
- destroy_workqueue(pool->release_wq);
- free_percpu(pool->unbuddied);
- kfree(pool);
-}
-
-static const struct movable_operations z3fold_mops;
-
-/**
- * z3fold_alloc() - allocates a region of a given size
- * @pool: z3fold pool from which to allocate
- * @size: size in bytes of the desired allocation
- * @gfp: gfp flags used if the pool needs to grow
- * @handle: handle of the new allocation
- *
- * This function will attempt to find a free region in the pool large enough to
- * satisfy the allocation request. A search of the unbuddied lists is
- * performed first. If no suitable free region is found, then a new page is
- * allocated and added to the pool to satisfy the request.
- *
- * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
- * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
- * a new page.
- */
-static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
- unsigned long *handle)
-{
- int chunks = size_to_chunks(size);
- struct z3fold_header *zhdr = NULL;
- struct page *page = NULL;
- enum buddy bud;
- bool can_sleep = gfpflags_allow_blocking(gfp);
-
- if (!size || (gfp & __GFP_HIGHMEM))
- return -EINVAL;
-
- if (size > PAGE_SIZE)
- return -ENOSPC;
-
- if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
- bud = HEADLESS;
- else {
-retry:
- zhdr = __z3fold_alloc(pool, size, can_sleep);
- if (zhdr) {
- bud = get_free_buddy(zhdr, chunks);
- if (bud == HEADLESS) {
- if (!put_z3fold_locked(zhdr))
- z3fold_page_unlock(zhdr);
- pr_err("No free chunks in unbuddied\n");
- WARN_ON(1);
- goto retry;
- }
- page = virt_to_page(zhdr);
- goto found;
- }
- bud = FIRST;
- }
-
- page = alloc_page(gfp);
- if (!page)
- return -ENOMEM;
-
- zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
- if (!zhdr) {
- __free_page(page);
- return -ENOMEM;
- }
- atomic64_inc(&pool->pages_nr);
-
- if (bud == HEADLESS) {
- set_bit(PAGE_HEADLESS, &page->private);
- goto headless;
- }
- if (can_sleep) {
- lock_page(page);
- __SetPageMovable(page, &z3fold_mops);
- unlock_page(page);
- } else {
- WARN_ON(!trylock_page(page));
- __SetPageMovable(page, &z3fold_mops);
- unlock_page(page);
- }
- z3fold_page_lock(zhdr);
-
-found:
- if (bud == FIRST)
- zhdr->first_chunks = chunks;
- else if (bud == LAST)
- zhdr->last_chunks = chunks;
- else {
- zhdr->middle_chunks = chunks;
- zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
- }
- add_to_unbuddied(pool, zhdr);
-
-headless:
- spin_lock(&pool->lock);
- *handle = encode_handle(zhdr, bud);
- spin_unlock(&pool->lock);
- if (bud != HEADLESS)
- z3fold_page_unlock(zhdr);
-
- return 0;
-}
-
-/**
- * z3fold_free() - frees the allocation associated with the given handle
- * @pool: pool in which the allocation resided
- * @handle: handle associated with the allocation returned by z3fold_alloc()
- *
- * In the case that the z3fold page in which the allocation resides is under
- * reclaim, as indicated by the PAGE_CLAIMED flag being set, this function
- * only sets the first|middle|last_chunks to 0. The page is actually freed
- * once all buddies are evicted (see z3fold_reclaim_page() below).
- */
-static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
-{
- struct z3fold_header *zhdr;
- struct page *page;
- enum buddy bud;
- bool page_claimed;
-
- zhdr = get_z3fold_header(handle);
- page = virt_to_page(zhdr);
- page_claimed = test_and_set_bit(PAGE_CLAIMED, &page->private);
-
- if (test_bit(PAGE_HEADLESS, &page->private)) {
- /* if a headless page is under reclaim, just leave.
- * NB: we use test_and_set_bit for a reason: if the bit
- * has not been set before, we release this page
- * immediately so we don't care about its value any more.
- */
- if (!page_claimed) {
- put_z3fold_header(zhdr);
- free_z3fold_page(page, true);
- atomic64_dec(&pool->pages_nr);
- }
- return;
- }
-
- /* Non-headless case */
- bud = handle_to_buddy(handle);
-
- switch (bud) {
- case FIRST:
- zhdr->first_chunks = 0;
- break;
- case MIDDLE:
- zhdr->middle_chunks = 0;
- break;
- case LAST:
- zhdr->last_chunks = 0;
- break;
- default:
- pr_err("%s: unknown bud %d\n", __func__, bud);
- WARN_ON(1);
- put_z3fold_header(zhdr);
- return;
- }
-
- if (!page_claimed)
- free_handle(handle, zhdr);
- if (put_z3fold_locked_list(zhdr))
- return;
- if (page_claimed) {
- /* the page has not been claimed by us */
- put_z3fold_header(zhdr);
- return;
- }
- if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
- clear_bit(PAGE_CLAIMED, &page->private);
- put_z3fold_header(zhdr);
- return;
- }
- if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
- zhdr->cpu = -1;
- kref_get(&zhdr->refcount);
- clear_bit(PAGE_CLAIMED, &page->private);
- do_compact_page(zhdr, true);
- return;
- }
- kref_get(&zhdr->refcount);
- clear_bit(PAGE_CLAIMED, &page->private);
- queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
- put_z3fold_header(zhdr);
-}
-
-/**
- * z3fold_map() - maps the allocation associated with the given handle
- * @pool: pool in which the allocation resides
- * @handle: handle associated with the allocation to be mapped
- *
- * Extracts the buddy number from handle and constructs the pointer to the
- * correct starting chunk within the page.
- *
- * Returns: a pointer to the mapped allocation
- */
-static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
-{
- struct z3fold_header *zhdr;
- struct page *page;
- void *addr;
- enum buddy buddy;
-
- zhdr = get_z3fold_header(handle);
- addr = zhdr;
- page = virt_to_page(zhdr);
-
- if (test_bit(PAGE_HEADLESS, &page->private))
- goto out;
-
- buddy = handle_to_buddy(handle);
- switch (buddy) {
- case FIRST:
- addr += ZHDR_SIZE_ALIGNED;
- break;
- case MIDDLE:
- addr += zhdr->start_middle << CHUNK_SHIFT;
- set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
- break;
- case LAST:
- addr += PAGE_SIZE - (handle_to_chunks(handle) << CHUNK_SHIFT);
- break;
- default:
- pr_err("unknown buddy id %d\n", buddy);
- WARN_ON(1);
- addr = NULL;
- break;
- }
-
- if (addr)
- zhdr->mapped_count++;
-out:
- put_z3fold_header(zhdr);
- return addr;
-}
-
-/**
- * z3fold_unmap() - unmaps the allocation associated with the given handle
- * @pool: pool in which the allocation resides
- * @handle: handle associated with the allocation to be unmapped
- */
-static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
-{
- struct z3fold_header *zhdr;
- struct page *page;
- enum buddy buddy;
-
- zhdr = get_z3fold_header(handle);
- page = virt_to_page(zhdr);
-
- if (test_bit(PAGE_HEADLESS, &page->private))
- return;
-
- buddy = handle_to_buddy(handle);
- if (buddy == MIDDLE)
- clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
- zhdr->mapped_count--;
- put_z3fold_header(zhdr);
-}
-
-/**
- * z3fold_get_pool_pages() - gets the z3fold pool size in pages
- * @pool: pool whose size is being queried
- *
- * Returns: size in pages of the given pool.
- */
-static u64 z3fold_get_pool_pages(struct z3fold_pool *pool)
-{
- return atomic64_read(&pool->pages_nr);
-}
-
-static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
-{
- struct z3fold_header *zhdr;
- struct z3fold_pool *pool;
-
- VM_BUG_ON_PAGE(PageIsolated(page), page);
-
- if (test_bit(PAGE_HEADLESS, &page->private))
- return false;
-
- zhdr = page_address(page);
- z3fold_page_lock(zhdr);
- if (test_bit(NEEDS_COMPACTING, &page->private) ||
- test_bit(PAGE_STALE, &page->private))
- goto out;
-
- if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0)
- goto out;
-
- if (test_and_set_bit(PAGE_CLAIMED, &page->private))
- goto out;
- pool = zhdr_to_pool(zhdr);
- spin_lock(&pool->lock);
- if (!list_empty(&zhdr->buddy))
- list_del_init(&zhdr->buddy);
- spin_unlock(&pool->lock);
-
- kref_get(&zhdr->refcount);
- z3fold_page_unlock(zhdr);
- return true;
-
-out:
- z3fold_page_unlock(zhdr);
- return false;
-}
-
-static int z3fold_page_migrate(struct page *newpage, struct page *page,
- enum migrate_mode mode)
-{
- struct z3fold_header *zhdr, *new_zhdr;
- struct z3fold_pool *pool;
-
- VM_BUG_ON_PAGE(!PageIsolated(page), page);
- VM_BUG_ON_PAGE(!test_bit(PAGE_CLAIMED, &page->private), page);
- VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
-
- zhdr = page_address(page);
- pool = zhdr_to_pool(zhdr);
-
- if (!z3fold_page_trylock(zhdr))
- return -EAGAIN;
- if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) {
- clear_bit(PAGE_CLAIMED, &page->private);
- z3fold_page_unlock(zhdr);
- return -EBUSY;
- }
- if (work_pending(&zhdr->work)) {
- z3fold_page_unlock(zhdr);
- return -EAGAIN;
- }
- new_zhdr = page_address(newpage);
- memcpy(new_zhdr, zhdr, PAGE_SIZE);
- newpage->private = page->private;
- set_bit(PAGE_MIGRATED, &page->private);
- z3fold_page_unlock(zhdr);
- spin_lock_init(&new_zhdr->page_lock);
- INIT_WORK(&new_zhdr->work, compact_page_work);
- /*
- * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
- * so we only have to reinitialize it.
- */
- INIT_LIST_HEAD(&new_zhdr->buddy);
- __ClearPageMovable(page);
-
- get_page(newpage);
- z3fold_page_lock(new_zhdr);
- if (new_zhdr->first_chunks)
- encode_handle(new_zhdr, FIRST);
- if (new_zhdr->last_chunks)
- encode_handle(new_zhdr, LAST);
- if (new_zhdr->middle_chunks)
- encode_handle(new_zhdr, MIDDLE);
- set_bit(NEEDS_COMPACTING, &newpage->private);
- new_zhdr->cpu = smp_processor_id();
- __SetPageMovable(newpage, &z3fold_mops);
- z3fold_page_unlock(new_zhdr);
-
- queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
-
- /* PAGE_CLAIMED and PAGE_MIGRATED are cleared now. */
- page->private = 0;
- put_page(page);
- return 0;
-}
-
-static void z3fold_page_putback(struct page *page)
-{
- struct z3fold_header *zhdr;
- struct z3fold_pool *pool;
-
- zhdr = page_address(page);
- pool = zhdr_to_pool(zhdr);
-
- z3fold_page_lock(zhdr);
- if (!list_empty(&zhdr->buddy))
- list_del_init(&zhdr->buddy);
- INIT_LIST_HEAD(&page->lru);
- if (put_z3fold_locked(zhdr))
- return;
- if (list_empty(&zhdr->buddy))
- add_to_unbuddied(pool, zhdr);
- clear_bit(PAGE_CLAIMED, &page->private);
- z3fold_page_unlock(zhdr);
-}
-
-static const struct movable_operations z3fold_mops = {
- .isolate_page = z3fold_page_isolate,
- .migrate_page = z3fold_page_migrate,
- .putback_page = z3fold_page_putback,
-};
-
-/*****************
- * zpool
- ****************/
-
-static void *z3fold_zpool_create(const char *name, gfp_t gfp)
-{
- return z3fold_create_pool(name, gfp);
-}
-
-static void z3fold_zpool_destroy(void *pool)
-{
- z3fold_destroy_pool(pool);
-}
-
-static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
- unsigned long *handle)
-{
- return z3fold_alloc(pool, size, gfp, handle);
-}
-static void z3fold_zpool_free(void *pool, unsigned long handle)
-{
- z3fold_free(pool, handle);
-}
-
-static void *z3fold_zpool_map(void *pool, unsigned long handle,
- enum zpool_mapmode mm)
-{
- return z3fold_map(pool, handle);
-}
-static void z3fold_zpool_unmap(void *pool, unsigned long handle)
-{
- z3fold_unmap(pool, handle);
-}
-
-static u64 z3fold_zpool_total_pages(void *pool)
-{
- return z3fold_get_pool_pages(pool);
-}
-
-static struct zpool_driver z3fold_zpool_driver = {
- .type = "z3fold",
- .sleep_mapped = true,
- .owner = THIS_MODULE,
- .create = z3fold_zpool_create,
- .destroy = z3fold_zpool_destroy,
- .malloc = z3fold_zpool_malloc,
- .free = z3fold_zpool_free,
- .map = z3fold_zpool_map,
- .unmap = z3fold_zpool_unmap,
- .total_pages = z3fold_zpool_total_pages,
-};
-
-MODULE_ALIAS("zpool-z3fold");
-
-static int __init init_z3fold(void)
-{
- /*
- * Make sure the z3fold header is not larger than the page size and
- * there has remaining spaces for its buddy.
- */
- BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE - CHUNK_SIZE);
- zpool_register_driver(&z3fold_zpool_driver);
-
- return 0;
-}
-
-static void __exit exit_z3fold(void)
-{
- zpool_unregister_driver(&z3fold_zpool_driver);
-}
-
-module_init(init_z3fold);
-module_exit(exit_z3fold);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
-MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");
projects / thirdparty / linux.git / commitdiff
