| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Vitaly Wool | 5824 | 95.27% | 25 | 41.67% |
| Miaohe Lin | 112 | 1.83% | 15 | 25.00% |
| Henry Burns | 68 | 1.11% | 4 | 6.67% |
| Xidong Wang | 23 | 0.38% | 1 | 1.67% |
| ruanjinjie | 21 | 0.34% | 1 | 1.67% |
| Domenico Cerasuolo | 18 | 0.29% | 1 | 1.67% |
| Matthew Wilcox | 16 | 0.26% | 2 | 3.33% |
| Qian Cai | 9 | 0.15% | 1 | 1.67% |
| Johannes Weiner | 7 | 0.11% | 2 | 3.33% |
| Tian Tao | 5 | 0.08% | 1 | 1.67% |
| zhong jiang | 3 | 0.05% | 1 | 1.67% |
| Uladzislau Rezki | 2 | 0.03% | 1 | 1.67% |
| Thomas Hebb | 1 | 0.02% | 1 | 1.67% |
| Xiu Jianfeng | 1 | 0.02% | 1 | 1.67% |
| Thomas Gleixner | 1 | 0.02% | 1 | 1.67% |
| Hui Su | 1 | 0.02% | 1 | 1.67% |
| Zhongkun He | 1 | 0.02% | 1 | 1.67% |
| Total | 6113 | 60 |
// 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 *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");
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