diff options
| -rw-r--r-- | mm/zsmalloc.c | 237 |
1 files changed, 205 insertions, 32 deletions
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 9445bee6b014..702bc3fd687a 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -113,7 +113,23 @@ * have room for two bit at least. */ #define OBJ_ALLOCATED_TAG 1 -#define OBJ_TAG_BITS 1 + +#ifdef CONFIG_ZPOOL +/* + * The second least-significant bit in the object's header identifies if the + * value stored at the header is a deferred handle from the last reclaim + * attempt. + * + * As noted above, this is valid because we have room for two bits. + */ +#define OBJ_DEFERRED_HANDLE_TAG 2 +#define OBJ_TAG_BITS 2 +#define OBJ_TAG_MASK (OBJ_ALLOCATED_TAG | OBJ_DEFERRED_HANDLE_TAG) +#else +#define OBJ_TAG_BITS 1 +#define OBJ_TAG_MASK OBJ_ALLOCATED_TAG +#endif /* CONFIG_ZPOOL */ + #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1) @@ -222,6 +238,12 @@ struct link_free { * Handle of allocated object. */ unsigned long handle; +#ifdef CONFIG_ZPOOL + /* + * Deferred handle of a reclaimed object. + */ + unsigned long deferred_handle; +#endif }; }; @@ -272,8 +294,6 @@ struct zspage { /* links the zspage to the lru list in the pool */ struct list_head lru; bool under_reclaim; - /* list of unfreed handles whose objects have been reclaimed */ - unsigned long *deferred_handles; #endif struct zs_pool *pool; @@ -897,7 +917,8 @@ static unsigned long handle_to_obj(unsigned long handle) return *(unsigned long *)handle; } -static bool obj_allocated(struct page *page, void *obj, unsigned long *phandle) +static bool obj_tagged(struct page *page, void *obj, unsigned long *phandle, + int tag) { unsigned long handle; struct zspage *zspage = get_zspage(page); @@ -908,13 +929,27 @@ static bool obj_allocated(struct page *page, void *obj, unsigned long *phandle) } else handle = *(unsigned long *)obj; - if (!(handle & OBJ_ALLOCATED_TAG)) + if (!(handle & tag)) return false; - *phandle = handle & ~OBJ_ALLOCATED_TAG; + /* Clear all tags before returning the handle */ + *phandle = handle & ~OBJ_TAG_MASK; return true; } +static inline bool obj_allocated(struct page *page, void *obj, unsigned long *phandle) +{ + return obj_tagged(page, obj, phandle, OBJ_ALLOCATED_TAG); +} + +#ifdef CONFIG_ZPOOL +static bool obj_stores_deferred_handle(struct page *page, void *obj, + unsigned long *phandle) +{ + return obj_tagged(page, obj, phandle, OBJ_DEFERRED_HANDLE_TAG); +} +#endif + static void reset_page(struct page *page) { __ClearPageMovable(page); @@ -946,22 +981,36 @@ unlock: } #ifdef CONFIG_ZPOOL +static unsigned long find_deferred_handle_obj(struct size_class *class, + struct page *page, int *obj_idx); + /* * Free all the deferred handles whose objects are freed in zs_free. */ -static void free_handles(struct zs_pool *pool, struct zspage *zspage) +static void free_handles(struct zs_pool *pool, struct size_class *class, + struct zspage *zspage) { - unsigned long handle = (unsigned long)zspage->deferred_handles; + int obj_idx = 0; + struct page *page = get_first_page(zspage); + unsigned long handle; - while (handle) { - unsigned long nxt_handle = handle_to_obj(handle); + while (1) { + handle = find_deferred_handle_obj(class, page, &obj_idx); + if (!handle) { + page = get_next_page(page); + if (!page) + break; + obj_idx = 0; + continue; + } cache_free_handle(pool, handle); - handle = nxt_handle; + obj_idx++; } } #else -static inline void free_handles(struct zs_pool *pool, struct zspage *zspage) {} +static inline void free_handles(struct zs_pool *pool, struct size_class *class, + struct zspage *zspage) {} #endif static void __free_zspage(struct zs_pool *pool, struct size_class *class, @@ -979,7 +1028,7 @@ static void __free_zspage(struct zs_pool *pool, struct size_class *class, VM_BUG_ON(fg != ZS_EMPTY); /* Free all deferred handles from zs_free */ - free_handles(pool, zspage); + free_handles(pool, class, zspage); next = page = get_first_page(zspage); do { @@ -1067,7 +1116,6 @@ static void init_zspage(struct size_class *class, struct zspage *zspage) #ifdef CONFIG_ZPOOL INIT_LIST_HEAD(&zspage->lru); zspage->under_reclaim = false; - zspage->deferred_handles = NULL; #endif set_freeobj(zspage, 0); @@ -1568,7 +1616,7 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp) } EXPORT_SYMBOL_GPL(zs_malloc); -static void obj_free(int class_size, unsigned long obj) +static void obj_free(int class_size, unsigned long obj, unsigned long *handle) { struct link_free *link; struct zspage *zspage; @@ -1582,15 +1630,29 @@ static void obj_free(int class_size, unsigned long obj) zspage = get_zspage(f_page); vaddr = kmap_atomic(f_page); - - /* Insert this object in containing zspage's freelist */ link = (struct link_free *)(vaddr + f_offset); - if (likely(!ZsHugePage(zspage))) - link->next = get_freeobj(zspage) << OBJ_TAG_BITS; - else - f_page->index = 0; + + if (handle) { +#ifdef CONFIG_ZPOOL + /* Stores the (deferred) handle in the object's header */ + *handle |= OBJ_DEFERRED_HANDLE_TAG; + *handle &= ~OBJ_ALLOCATED_TAG; + + if (likely(!ZsHugePage(zspage))) + link->deferred_handle = *handle; + else + f_page->index = *handle; +#endif + } else { + /* Insert this object in containing zspage's freelist */ + if (likely(!ZsHugePage(zspage))) + link->next = get_freeobj(zspage) << OBJ_TAG_BITS; + else + f_page->index = 0; + set_freeobj(zspage, f_objidx); + } + kunmap_atomic(vaddr); - set_freeobj(zspage, f_objidx); mod_zspage_inuse(zspage, -1); } @@ -1615,7 +1677,6 @@ void zs_free(struct zs_pool *pool, unsigned long handle) zspage = get_zspage(f_page); class = zspage_class(pool, zspage); - obj_free(class->size, obj); class_stat_dec(class, OBJ_USED, 1); #ifdef CONFIG_ZPOOL @@ -1624,15 +1685,15 @@ void zs_free(struct zs_pool *pool, unsigned long handle) * Reclaim needs the handles during writeback. It'll free * them along with the zspage when it's done with them. * - * Record current deferred handle at the memory location - * whose address is given by handle. + * Record current deferred handle in the object's header. */ - record_obj(handle, (unsigned long)zspage->deferred_handles); - zspage->deferred_handles = (unsigned long *)handle; + obj_free(class->size, obj, &handle); spin_unlock(&pool->lock); return; } #endif + obj_free(class->size, obj, NULL); + fullness = fix_fullness_group(class, zspage); if (fullness == ZS_EMPTY) free_zspage(pool, class, zspage); @@ -1713,11 +1774,11 @@ static void zs_object_copy(struct size_class *class, unsigned long dst, } /* - * Find alloced object in zspage from index object and + * Find object with a certain tag in zspage from index object and * return handle. */ -static unsigned long find_alloced_obj(struct size_class *class, - struct page *page, int *obj_idx) +static unsigned long find_tagged_obj(struct size_class *class, + struct page *page, int *obj_idx, int tag) { unsigned int offset; int index = *obj_idx; @@ -1728,7 +1789,7 @@ static unsigned long find_alloced_obj(struct size_class *class, offset += class->size * index; while (offset < PAGE_SIZE) { - if (obj_allocated(page, addr + offset, &handle)) + if (obj_tagged(page, addr + offset, &handle, tag)) break; offset += class->size; @@ -1742,6 +1803,28 @@ static unsigned long find_alloced_obj(struct size_class *class, return handle; } +/* + * Find alloced object in zspage from index object and + * return handle. + */ +static unsigned long find_alloced_obj(struct size_class *class, + struct page *page, int *obj_idx) +{ + return find_tagged_obj(class, page, obj_idx, OBJ_ALLOCATED_TAG); +} + +#ifdef CONFIG_ZPOOL +/* + * Find object storing a deferred handle in header in zspage from index object + * and return handle. + */ +static unsigned long find_deferred_handle_obj(struct size_class *class, + struct page *page, int *obj_idx) +{ + return find_tagged_obj(class, page, obj_idx, OBJ_DEFERRED_HANDLE_TAG); +} +#endif + struct zs_compact_control { /* Source spage for migration which could be a subpage of zspage */ struct page *s_page; @@ -1784,7 +1867,7 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class, zs_object_copy(class, free_obj, used_obj); obj_idx++; record_obj(handle, free_obj); - obj_free(class->size, used_obj); + obj_free(class->size, used_obj, NULL); } /* Remember last position in this iteration */ @@ -2478,6 +2561,90 @@ void zs_destroy_pool(struct zs_pool *pool) EXPORT_SYMBOL_GPL(zs_destroy_pool); #ifdef CONFIG_ZPOOL +static void restore_freelist(struct zs_pool *pool, struct size_class *class, + struct zspage *zspage) +{ + unsigned int obj_idx = 0; + unsigned long handle, off = 0; /* off is within-page offset */ + struct page *page = get_first_page(zspage); + struct link_free *prev_free = NULL; + void *prev_page_vaddr = NULL; + + /* in case no free object found */ + set_freeobj(zspage, (unsigned int)(-1UL)); + + while (page) { + void *vaddr = kmap_atomic(page); + struct page *next_page; + + while (off < PAGE_SIZE) { + void *obj_addr = vaddr + off; + + /* skip allocated object */ + if (obj_allocated(page, obj_addr, &handle)) { + obj_idx++; + off += class->size; + continue; + } + + /* free deferred handle from reclaim attempt */ + if (obj_stores_deferred_handle(page, obj_addr, &handle)) + cache_free_handle(pool, handle); + + if (prev_free) + prev_free->next = obj_idx << OBJ_TAG_BITS; + else /* first free object found */ + set_freeobj(zspage, obj_idx); + + prev_free = (struct link_free *)vaddr + off / sizeof(*prev_free); + /* if last free object in a previous page, need to unmap */ + if (prev_page_vaddr) { + kunmap_atomic(prev_page_vaddr); + prev_page_vaddr = NULL; + } + + obj_idx++; + off += class->size; + } + + /* + * Handle the last (full or partial) object on this page. + */ + next_page = get_next_page(page); + if (next_page) { + if (!prev_free || prev_page_vaddr) { + /* + * There is no free object in this page, so we can safely + * unmap it. + */ + kunmap_atomic(vaddr); + } else { + /* update prev_page_vaddr since prev_free is on this page */ + prev_page_vaddr = vaddr; + } + } else { /* this is the last page */ + if (prev_free) { + /* + * Reset OBJ_TAG_BITS bit to last link to tell + * whether it's allocated object or not. + */ + prev_free->next = -1UL << OBJ_TAG_BITS; + } + + /* unmap previous page (if not done yet) */ + if (prev_page_vaddr) { + kunmap_atomic(prev_page_vaddr); + prev_page_vaddr = NULL; + } + + kunmap_atomic(vaddr); + } + + page = next_page; + off %= PAGE_SIZE; + } +} + static int zs_reclaim_page(struct zs_pool *pool, unsigned int retries) { int i, obj_idx, ret = 0; @@ -2561,6 +2728,12 @@ next: return 0; } + /* + * Eviction fails on one of the handles, so we need to restore zspage. + * We need to rebuild its freelist (and free stored deferred handles), + * put it back to the correct size class, and add it to the LRU list. + */ + restore_freelist(pool, class, zspage); putback_zspage(class, zspage); list_add(&zspage->lru, &pool->lru); unlock_zspage(zspage); |