X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=mm%2Fz3fold.c;h=05bdf90646e7937ab8435327f785afbb0deaabf1;hb=e5b7d90fd09dd5db2ca91dd716e721e51c9a861f;hp=75b7962439ff8b21b9cacb6a542d21ad8313af3b;hpb=8d7ead5c69dfa928322777c532fa0770af319202;p=linux.git diff --git a/mm/z3fold.c b/mm/z3fold.c index 75b7962439ff..05bdf90646e7 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -41,7 +41,6 @@ #include #include #include -#include #include #include @@ -146,8 +145,6 @@ struct z3fold_header { * @release_wq: workqueue for safe page release * @work: work_struct for safe page release * @inode: inode for z3fold pseudo filesystem - * @destroying: bool to stop migration once we start destruction - * @isolated: int to count the number of pages currently in isolation * * This structure is allocated at pool creation time and maintains metadata * pertaining to a particular z3fold pool. @@ -166,11 +163,8 @@ struct z3fold_pool { const struct zpool_ops *zpool_ops; struct workqueue_struct *compact_wq; struct workqueue_struct *release_wq; - struct wait_queue_head isolate_wait; struct work_struct work; struct inode *inode; - bool destroying; - int isolated; }; /* @@ -301,14 +295,11 @@ static void z3fold_unregister_migration(struct z3fold_pool *pool) } /* Initializes the z3fold header of a newly allocated z3fold page */ -static struct z3fold_header *init_z3fold_page(struct page *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 = alloc_slots(pool, gfp); - - if (!slots) - return NULL; + struct z3fold_buddy_slots *slots; INIT_LIST_HEAD(&page->lru); clear_bit(PAGE_HEADLESS, &page->private); @@ -316,6 +307,12 @@ static struct z3fold_header *init_z3fold_page(struct page *page, clear_bit(NEEDS_COMPACTING, &page->private); clear_bit(PAGE_STALE, &page->private); clear_bit(PAGE_CLAIMED, &page->private); + if (headless) + return zhdr; + + slots = alloc_slots(pool, gfp); + if (!slots) + return NULL; spin_lock_init(&zhdr->page_lock); kref_init(&zhdr->refcount); @@ -372,9 +369,10 @@ static inline int __idx(struct z3fold_header *zhdr, enum buddy bud) * Encodes the handle of a particular buddy within a z3fold page * Pool lock should be held as this function accesses first_num */ -static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud) +static unsigned long __encode_handle(struct z3fold_header *zhdr, + struct z3fold_buddy_slots *slots, + enum buddy bud) { - struct z3fold_buddy_slots *slots; unsigned long h = (unsigned long)zhdr; int idx = 0; @@ -391,11 +389,15 @@ static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud) if (bud == LAST) h |= (zhdr->last_chunks << BUDDY_SHIFT); - slots = zhdr->slots; slots->slot[idx] = h; 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); +} + /* Returns the z3fold page where a given handle is stored */ static inline struct z3fold_header *handle_to_z3fold_header(unsigned long h) { @@ -630,6 +632,7 @@ static void do_compact_page(struct z3fold_header *zhdr, bool locked) } if (unlikely(PageIsolated(page) || + test_bit(PAGE_CLAIMED, &page->private) || test_bit(PAGE_STALE, &page->private))) { z3fold_page_unlock(zhdr); return; @@ -775,7 +778,6 @@ static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp, goto out_c; spin_lock_init(&pool->lock); spin_lock_init(&pool->stale_lock); - init_waitqueue_head(&pool->isolate_wait); pool->unbuddied = __alloc_percpu(sizeof(struct list_head)*NCHUNKS, 2); if (!pool->unbuddied) goto out_pool; @@ -815,15 +817,6 @@ static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp, return NULL; } -static bool pool_isolated_are_drained(struct z3fold_pool *pool) -{ - bool ret; - - spin_lock(&pool->lock); - ret = pool->isolated == 0; - spin_unlock(&pool->lock); - return ret; -} /** * z3fold_destroy_pool() - destroys an existing z3fold pool * @pool: the z3fold pool to be destroyed @@ -833,22 +826,6 @@ static bool pool_isolated_are_drained(struct z3fold_pool *pool) static void z3fold_destroy_pool(struct z3fold_pool *pool) { kmem_cache_destroy(pool->c_handle); - /* - * We set pool-> destroying under lock to ensure that - * z3fold_page_isolate() sees any changes to destroying. This way we - * avoid the need for any memory barriers. - */ - - spin_lock(&pool->lock); - pool->destroying = true; - spin_unlock(&pool->lock); - - /* - * We need to ensure that no pages are being migrated while we destroy - * these workqueues, as migration can queue work on either of the - * workqueues. - */ - wait_event(pool->isolate_wait, !pool_isolated_are_drained(pool)); /* * We need to destroy pool->compact_wq before pool->release_wq, @@ -956,7 +933,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp, if (!page) return -ENOMEM; - zhdr = init_z3fold_page(page, pool, gfp); + zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp); if (!zhdr) { __free_page(page); return -ENOMEM; @@ -1132,6 +1109,7 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries) struct z3fold_header *zhdr = NULL; struct page *page = NULL; struct list_head *pos; + struct z3fold_buddy_slots slots; unsigned long first_handle = 0, middle_handle = 0, last_handle = 0; spin_lock(&pool->lock); @@ -1150,16 +1128,22 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries) /* this bit could have been set by free, in which case * we pass over to the next page in the pool. */ - if (test_and_set_bit(PAGE_CLAIMED, &page->private)) + if (test_and_set_bit(PAGE_CLAIMED, &page->private)) { + page = NULL; continue; + } - if (unlikely(PageIsolated(page))) + if (unlikely(PageIsolated(page))) { + clear_bit(PAGE_CLAIMED, &page->private); + page = NULL; continue; + } + zhdr = page_address(page); if (test_bit(PAGE_HEADLESS, &page->private)) break; - zhdr = page_address(page); if (!z3fold_page_trylock(zhdr)) { + clear_bit(PAGE_CLAIMED, &page->private); zhdr = NULL; continue; /* can't evict at this point */ } @@ -1177,26 +1161,30 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries) if (!test_bit(PAGE_HEADLESS, &page->private)) { /* - * We need encode the handles before unlocking, since - * we can race with free that will set - * (first|last)_chunks to 0 + * We need encode the handles before unlocking, and + * use our local slots structure because z3fold_free + * can zero out zhdr->slots and we can't do much + * about that */ first_handle = 0; last_handle = 0; middle_handle = 0; if (zhdr->first_chunks) - first_handle = encode_handle(zhdr, FIRST); + first_handle = __encode_handle(zhdr, &slots, + FIRST); if (zhdr->middle_chunks) - middle_handle = encode_handle(zhdr, MIDDLE); + middle_handle = __encode_handle(zhdr, &slots, + MIDDLE); if (zhdr->last_chunks) - last_handle = encode_handle(zhdr, LAST); + last_handle = __encode_handle(zhdr, &slots, + LAST); /* * it's safe to unlock here because we hold a * reference to this page */ z3fold_page_unlock(zhdr); } else { - first_handle = encode_handle(zhdr, HEADLESS); + first_handle = __encode_handle(zhdr, &slots, HEADLESS); last_handle = middle_handle = 0; } @@ -1226,9 +1214,9 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries) spin_lock(&pool->lock); list_add(&page->lru, &pool->lru); spin_unlock(&pool->lock); + clear_bit(PAGE_CLAIMED, &page->private); } else { z3fold_page_lock(zhdr); - clear_bit(PAGE_CLAIMED, &page->private); if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) { atomic64_dec(&pool->pages_nr); @@ -1243,6 +1231,7 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries) list_add(&page->lru, &pool->lru); spin_unlock(&pool->lock); z3fold_page_unlock(zhdr); + clear_bit(PAGE_CLAIMED, &page->private); } /* We started off locked to we need to lock the pool back */ @@ -1339,28 +1328,6 @@ static u64 z3fold_get_pool_size(struct z3fold_pool *pool) return atomic64_read(&pool->pages_nr); } -/* - * z3fold_dec_isolated() expects to be called while pool->lock is held. - */ -static void z3fold_dec_isolated(struct z3fold_pool *pool) -{ - assert_spin_locked(&pool->lock); - VM_BUG_ON(pool->isolated <= 0); - pool->isolated--; - - /* - * If we have no more isolated pages, we have to see if - * z3fold_destroy_pool() is waiting for a signal. - */ - if (pool->isolated == 0 && waitqueue_active(&pool->isolate_wait)) - wake_up_all(&pool->isolate_wait); -} - -static void z3fold_inc_isolated(struct z3fold_pool *pool) -{ - pool->isolated++; -} - static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode) { struct z3fold_header *zhdr; @@ -1369,7 +1336,8 @@ static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode) VM_BUG_ON_PAGE(!PageMovable(page), page); VM_BUG_ON_PAGE(PageIsolated(page), page); - if (test_bit(PAGE_HEADLESS, &page->private)) + if (test_bit(PAGE_HEADLESS, &page->private) || + test_bit(PAGE_CLAIMED, &page->private)) return false; zhdr = page_address(page); @@ -1387,34 +1355,6 @@ static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode) spin_lock(&pool->lock); if (!list_empty(&page->lru)) list_del(&page->lru); - /* - * We need to check for destruction while holding pool->lock, as - * otherwise destruction could see 0 isolated pages, and - * proceed. - */ - if (unlikely(pool->destroying)) { - spin_unlock(&pool->lock); - /* - * If this page isn't stale, somebody else holds a - * reference to it. Let't drop our refcount so that they - * can call the release logic. - */ - if (unlikely(kref_put(&zhdr->refcount, - release_z3fold_page_locked))) { - /* - * If we get here we have kref problems, so we - * should freak out. - */ - WARN(1, "Z3fold is experiencing kref problems\n"); - z3fold_page_unlock(zhdr); - return false; - } - z3fold_page_unlock(zhdr); - return false; - } - - - z3fold_inc_isolated(pool); spin_unlock(&pool->lock); z3fold_page_unlock(zhdr); return true; @@ -1483,10 +1423,6 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work); - spin_lock(&pool->lock); - z3fold_dec_isolated(pool); - spin_unlock(&pool->lock); - page_mapcount_reset(page); put_page(page); return 0; @@ -1506,14 +1442,10 @@ static void z3fold_page_putback(struct page *page) INIT_LIST_HEAD(&page->lru); if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) { atomic64_dec(&pool->pages_nr); - spin_lock(&pool->lock); - z3fold_dec_isolated(pool); - spin_unlock(&pool->lock); return; } spin_lock(&pool->lock); list_add(&page->lru, &pool->lru); - z3fold_dec_isolated(pool); spin_unlock(&pool->lock); z3fold_page_unlock(zhdr); }