| /* |
| * SLOB Allocator: Simple List Of Blocks |
| * |
| * Matt Mackall <mpm@selenic.com> 12/30/03 |
| * |
| * NUMA support by Paul Mundt, 2007. |
| * |
| * How SLOB works: |
| * |
| * The core of SLOB is a traditional K&R style heap allocator, with |
| * support for returning aligned objects. The granularity of this |
| * allocator is as little as 2 bytes, however typically most architectures |
| * will require 4 bytes on 32-bit and 8 bytes on 64-bit. |
| * |
| * The slob heap is a set of linked list of pages from alloc_pages(), |
| * and within each page, there is a singly-linked list of free blocks |
| * (slob_t). The heap is grown on demand. To reduce fragmentation, |
| * heap pages are segregated into three lists, with objects less than |
| * 256 bytes, objects less than 1024 bytes, and all other objects. |
| * |
| * Allocation from heap involves first searching for a page with |
| * sufficient free blocks (using a next-fit-like approach) followed by |
| * a first-fit scan of the page. Deallocation inserts objects back |
| * into the free list in address order, so this is effectively an |
| * address-ordered first fit. |
| * |
| * Above this is an implementation of kmalloc/kfree. Blocks returned |
| * from kmalloc are prepended with a 4-byte header with the kmalloc size. |
| * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls |
| * alloc_pages() directly, allocating compound pages so the page order |
| * does not have to be separately tracked, and also stores the exact |
| * allocation size in page->private so that it can be used to accurately |
| * provide ksize(). These objects are detected in kfree() because slob_page() |
| * is false for them. |
| * |
| * SLAB is emulated on top of SLOB by simply calling constructors and |
| * destructors for every SLAB allocation. Objects are returned with the |
| * 4-byte alignment unless the SLAB_HWCACHE_ALIGN flag is set, in which |
| * case the low-level allocator will fragment blocks to create the proper |
| * alignment. Again, objects of page-size or greater are allocated by |
| * calling alloc_pages(). As SLAB objects know their size, no separate |
| * size bookkeeping is necessary and there is essentially no allocation |
| * space overhead, and compound pages aren't needed for multi-page |
| * allocations. |
| * |
| * NUMA support in SLOB is fairly simplistic, pushing most of the real |
| * logic down to the page allocator, and simply doing the node accounting |
| * on the upper levels. In the event that a node id is explicitly |
| * provided, alloc_pages_node() with the specified node id is used |
| * instead. The common case (or when the node id isn't explicitly provided) |
| * will default to the current node, as per numa_node_id(). |
| * |
| * Node aware pages are still inserted in to the global freelist, and |
| * these are scanned for by matching against the node id encoded in the |
| * page flags. As a result, block allocations that can be satisfied from |
| * the freelist will only be done so on pages residing on the same node, |
| * in order to prevent random node placement. |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/slab.h> |
| #include <linux/mm.h> |
| #include <linux/cache.h> |
| #include <linux/init.h> |
| #include <linux/module.h> |
| #include <linux/rcupdate.h> |
| #include <linux/list.h> |
| #include <linux/kmemtrace.h> |
| #include <asm/atomic.h> |
| |
| /* |
| * slob_block has a field 'units', which indicates size of block if +ve, |
| * or offset of next block if -ve (in SLOB_UNITs). |
| * |
| * Free blocks of size 1 unit simply contain the offset of the next block. |
| * Those with larger size contain their size in the first SLOB_UNIT of |
| * memory, and the offset of the next free block in the second SLOB_UNIT. |
| */ |
| #if PAGE_SIZE <= (32767 * 2) |
| typedef s16 slobidx_t; |
| #else |
| typedef s32 slobidx_t; |
| #endif |
| |
| struct slob_block { |
| slobidx_t units; |
| }; |
| typedef struct slob_block slob_t; |
| |
| /* |
| * We use struct page fields to manage some slob allocation aspects, |
| * however to avoid the horrible mess in include/linux/mm_types.h, we'll |
| * just define our own struct page type variant here. |
| */ |
| struct slob_page { |
| union { |
| struct { |
| unsigned long flags; /* mandatory */ |
| atomic_t _count; /* mandatory */ |
| slobidx_t units; /* free units left in page */ |
| unsigned long pad[2]; |
| slob_t *free; /* first free slob_t in page */ |
| struct list_head list; /* linked list of free pages */ |
| }; |
| struct page page; |
| }; |
| }; |
| static inline void struct_slob_page_wrong_size(void) |
| { BUILD_BUG_ON(sizeof(struct slob_page) != sizeof(struct page)); } |
| |
| /* |
| * free_slob_page: call before a slob_page is returned to the page allocator. |
| */ |
| static inline void free_slob_page(struct slob_page *sp) |
| { |
| reset_page_mapcount(&sp->page); |
| sp->page.mapping = NULL; |
| } |
| |
| /* |
| * All partially free slob pages go on these lists. |
| */ |
| #define SLOB_BREAK1 256 |
| #define SLOB_BREAK2 1024 |
| static LIST_HEAD(free_slob_small); |
| static LIST_HEAD(free_slob_medium); |
| static LIST_HEAD(free_slob_large); |
| |
| /* |
| * is_slob_page: True for all slob pages (false for bigblock pages) |
| */ |
| static inline int is_slob_page(struct slob_page *sp) |
| { |
| return PageSlobPage((struct page *)sp); |
| } |
| |
| static inline void set_slob_page(struct slob_page *sp) |
| { |
| __SetPageSlobPage((struct page *)sp); |
| } |
| |
| static inline void clear_slob_page(struct slob_page *sp) |
| { |
| __ClearPageSlobPage((struct page *)sp); |
| } |
| |
| static inline struct slob_page *slob_page(const void *addr) |
| { |
| return (struct slob_page *)virt_to_page(addr); |
| } |
| |
| /* |
| * slob_page_free: true for pages on free_slob_pages list. |
| */ |
| static inline int slob_page_free(struct slob_page *sp) |
| { |
| return PageSlobFree((struct page *)sp); |
| } |
| |
| static void set_slob_page_free(struct slob_page *sp, struct list_head *list) |
| { |
| list_add(&sp->list, list); |
| __SetPageSlobFree((struct page *)sp); |
| } |
| |
| static inline void clear_slob_page_free(struct slob_page *sp) |
| { |
| list_del(&sp->list); |
| __ClearPageSlobFree((struct page *)sp); |
| } |
| |
| #define SLOB_UNIT sizeof(slob_t) |
| #define SLOB_UNITS(size) (((size) + SLOB_UNIT - 1)/SLOB_UNIT) |
| #define SLOB_ALIGN L1_CACHE_BYTES |
| |
| /* |
| * struct slob_rcu is inserted at the tail of allocated slob blocks, which |
| * were created with a SLAB_DESTROY_BY_RCU slab. slob_rcu is used to free |
| * the block using call_rcu. |
| */ |
| struct slob_rcu { |
| struct rcu_head head; |
| int size; |
| }; |
| |
| /* |
| * slob_lock protects all slob allocator structures. |
| */ |
| static DEFINE_SPINLOCK(slob_lock); |
| |
| /* |
| * Encode the given size and next info into a free slob block s. |
| */ |
| static void set_slob(slob_t *s, slobidx_t size, slob_t *next) |
| { |
| slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK); |
| slobidx_t offset = next - base; |
| |
| if (size > 1) { |
| s[0].units = size; |
| s[1].units = offset; |
| } else |
| s[0].units = -offset; |
| } |
| |
| /* |
| * Return the size of a slob block. |
| */ |
| static slobidx_t slob_units(slob_t *s) |
| { |
| if (s->units > 0) |
| return s->units; |
| return 1; |
| } |
| |
| /* |
| * Return the next free slob block pointer after this one. |
| */ |
| static slob_t *slob_next(slob_t *s) |
| { |
| slob_t *base = (slob_t *)((unsigned long)s & PAGE_MASK); |
| slobidx_t next; |
| |
| if (s[0].units < 0) |
| next = -s[0].units; |
| else |
| next = s[1].units; |
| return base+next; |
| } |
| |
| /* |
| * Returns true if s is the last free block in its page. |
| */ |
| static int slob_last(slob_t *s) |
| { |
| return !((unsigned long)slob_next(s) & ~PAGE_MASK); |
| } |
| |
| static void *slob_new_pages(gfp_t gfp, int order, int node) |
| { |
| void *page; |
| |
| #ifdef CONFIG_NUMA |
| if (node != -1) |
| page = alloc_pages_node(node, gfp, order); |
| else |
| #endif |
| page = alloc_pages(gfp, order); |
| |
| if (!page) |
| return NULL; |
| |
| return page_address(page); |
| } |
| |
| static void slob_free_pages(void *b, int order) |
| { |
| free_pages((unsigned long)b, order); |
| } |
| |
| /* |
| * Allocate a slob block within a given slob_page sp. |
| */ |
| static void *slob_page_alloc(struct slob_page *sp, size_t size, int align) |
| { |
| slob_t *prev, *cur, *aligned = NULL; |
| int delta = 0, units = SLOB_UNITS(size); |
| |
| for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) { |
| slobidx_t avail = slob_units(cur); |
| |
| if (align) { |
| aligned = (slob_t *)ALIGN((unsigned long)cur, align); |
| delta = aligned - cur; |
| } |
| if (avail >= units + delta) { /* room enough? */ |
| slob_t *next; |
| |
| if (delta) { /* need to fragment head to align? */ |
| next = slob_next(cur); |
| set_slob(aligned, avail - delta, next); |
| set_slob(cur, delta, aligned); |
| prev = cur; |
| cur = aligned; |
| avail = slob_units(cur); |
| } |
| |
| next = slob_next(cur); |
| if (avail == units) { /* exact fit? unlink. */ |
| if (prev) |
| set_slob(prev, slob_units(prev), next); |
| else |
| sp->free = next; |
| } else { /* fragment */ |
| if (prev) |
| set_slob(prev, slob_units(prev), cur + units); |
| else |
| sp->free = cur + units; |
| set_slob(cur + units, avail - units, next); |
| } |
| |
| sp->units -= units; |
| if (!sp->units) |
| clear_slob_page_free(sp); |
| return cur; |
| } |
| if (slob_last(cur)) |
| return NULL; |
| } |
| } |
| |
| /* |
| * slob_alloc: entry point into the slob allocator. |
| */ |
| static void *slob_alloc(size_t size, gfp_t gfp, int align, int node) |
| { |
| struct slob_page *sp; |
| struct list_head *prev; |
| struct list_head *slob_list; |
| slob_t *b = NULL; |
| unsigned long flags; |
| |
| if (size < SLOB_BREAK1) |
| slob_list = &free_slob_small; |
| else if (size < SLOB_BREAK2) |
| slob_list = &free_slob_medium; |
| else |
| slob_list = &free_slob_large; |
| |
| spin_lock_irqsave(&slob_lock, flags); |
| /* Iterate through each partially free page, try to find room */ |
| list_for_each_entry(sp, slob_list, list) { |
| #ifdef CONFIG_NUMA |
| /* |
| * If there's a node specification, search for a partial |
| * page with a matching node id in the freelist. |
| */ |
| if (node != -1 && page_to_nid(&sp->page) != node) |
| continue; |
| #endif |
| /* Enough room on this page? */ |
| if (sp->units < SLOB_UNITS(size)) |
| continue; |
| |
| /* Attempt to alloc */ |
| prev = sp->list.prev; |
| b = slob_page_alloc(sp, size, align); |
| if (!b) |
| continue; |
| |
| /* Improve fragment distribution and reduce our average |
| * search time by starting our next search here. (see |
| * Knuth vol 1, sec 2.5, pg 449) */ |
| if (prev != slob_list->prev && |
| slob_list->next != prev->next) |
| list_move_tail(slob_list, prev->next); |
| break; |
| } |
| spin_unlock_irqrestore(&slob_lock, flags); |
| |
| /* Not enough space: must allocate a new page */ |
| if (!b) { |
| b = slob_new_pages(gfp & ~__GFP_ZERO, 0, node); |
| if (!b) |
| return NULL; |
| sp = slob_page(b); |
| set_slob_page(sp); |
| |
| spin_lock_irqsave(&slob_lock, flags); |
| sp->units = SLOB_UNITS(PAGE_SIZE); |
| sp->free = b; |
| INIT_LIST_HEAD(&sp->list); |
| set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE)); |
| set_slob_page_free(sp, slob_list); |
| b = slob_page_alloc(sp, size, align); |
| BUG_ON(!b); |
| spin_unlock_irqrestore(&slob_lock, flags); |
| } |
| if (unlikely((gfp & __GFP_ZERO) && b)) |
| memset(b, 0, size); |
| return b; |
| } |
| |
| /* |
| * slob_free: entry point into the slob allocator. |
| */ |
| static void slob_free(void *block, int size) |
| { |
| struct slob_page *sp; |
| slob_t *prev, *next, *b = (slob_t *)block; |
| slobidx_t units; |
| unsigned long flags; |
| |
| if (unlikely(ZERO_OR_NULL_PTR(block))) |
| return; |
| BUG_ON(!size); |
| |
| sp = slob_page(block); |
| units = SLOB_UNITS(size); |
| |
| spin_lock_irqsave(&slob_lock, flags); |
| |
| if (sp->units + units == SLOB_UNITS(PAGE_SIZE)) { |
| /* Go directly to page allocator. Do not pass slob allocator */ |
| if (slob_page_free(sp)) |
| clear_slob_page_free(sp); |
| spin_unlock_irqrestore(&slob_lock, flags); |
| clear_slob_page(sp); |
| free_slob_page(sp); |
| free_page((unsigned long)b); |
| return; |
| } |
| |
| if (!slob_page_free(sp)) { |
| /* This slob page is about to become partially free. Easy! */ |
| sp->units = units; |
| sp->free = b; |
| set_slob(b, units, |
| (void *)((unsigned long)(b + |
| SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK)); |
| set_slob_page_free(sp, &free_slob_small); |
| goto out; |
| } |
| |
| /* |
| * Otherwise the page is already partially free, so find reinsertion |
| * point. |
| */ |
| sp->units += units; |
| |
| if (b < sp->free) { |
| if (b + units == sp->free) { |
| units += slob_units(sp->free); |
| sp->free = slob_next(sp->free); |
| } |
| set_slob(b, units, sp->free); |
| sp->free = b; |
| } else { |
| prev = sp->free; |
| next = slob_next(prev); |
| while (b > next) { |
| prev = next; |
| next = slob_next(prev); |
| } |
| |
| if (!slob_last(prev) && b + units == next) { |
| units += slob_units(next); |
| set_slob(b, units, slob_next(next)); |
| } else |
| set_slob(b, units, next); |
| |
| if (prev + slob_units(prev) == b) { |
| units = slob_units(b) + slob_units(prev); |
| set_slob(prev, units, slob_next(b)); |
| } else |
| set_slob(prev, slob_units(prev), b); |
| } |
| out: |
| spin_unlock_irqrestore(&slob_lock, flags); |
| } |
| |
| /* |
| * End of slob allocator proper. Begin kmem_cache_alloc and kmalloc frontend. |
| */ |
| |
| #ifndef ARCH_KMALLOC_MINALIGN |
| #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long) |
| #endif |
| |
| #ifndef ARCH_SLAB_MINALIGN |
| #define ARCH_SLAB_MINALIGN __alignof__(unsigned long) |
| #endif |
| |
| void *__kmalloc_node(size_t size, gfp_t gfp, int node) |
| { |
| unsigned int *m; |
| int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); |
| void *ret; |
| |
| lockdep_trace_alloc(gfp); |
| |
| if (size < PAGE_SIZE - align) { |
| if (!size) |
| return ZERO_SIZE_PTR; |
| |
| m = slob_alloc(size + align, gfp, align, node); |
| |
| if (!m) |
| return NULL; |
| *m = size; |
| ret = (void *)m + align; |
| |
| trace_kmalloc_node(_RET_IP_, ret, |
| size, size + align, gfp, node); |
| } else { |
| unsigned int order = get_order(size); |
| |
| ret = slob_new_pages(gfp | __GFP_COMP, get_order(size), node); |
| if (ret) { |
| struct page *page; |
| page = virt_to_page(ret); |
| page->private = size; |
| } |
| |
| trace_kmalloc_node(_RET_IP_, ret, |
| size, PAGE_SIZE << order, gfp, node); |
| } |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(__kmalloc_node); |
| |
| void kfree(const void *block) |
| { |
| struct slob_page *sp; |
| |
| trace_kfree(_RET_IP_, block); |
| |
| if (unlikely(ZERO_OR_NULL_PTR(block))) |
| return; |
| |
| sp = slob_page(block); |
| if (is_slob_page(sp)) { |
| int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); |
| unsigned int *m = (unsigned int *)(block - align); |
| slob_free(m, *m + align); |
| } else |
| put_page(&sp->page); |
| } |
| EXPORT_SYMBOL(kfree); |
| |
| /* can't use ksize for kmem_cache_alloc memory, only kmalloc */ |
| size_t ksize(const void *block) |
| { |
| struct slob_page *sp; |
| |
| BUG_ON(!block); |
| if (unlikely(block == ZERO_SIZE_PTR)) |
| return 0; |
| |
| sp = slob_page(block); |
| if (is_slob_page(sp)) { |
| int align = max(ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); |
| unsigned int *m = (unsigned int *)(block - align); |
| return SLOB_UNITS(*m) * SLOB_UNIT; |
| } else |
| return sp->page.private; |
| } |
| EXPORT_SYMBOL(ksize); |
| |
| struct kmem_cache { |
| unsigned int size, align; |
| unsigned long flags; |
| const char *name; |
| void (*ctor)(void *); |
| }; |
| |
| struct kmem_cache *kmem_cache_create(const char *name, size_t size, |
| size_t align, unsigned long flags, void (*ctor)(void *)) |
| { |
| struct kmem_cache *c; |
| |
| c = slob_alloc(sizeof(struct kmem_cache), |
| GFP_KERNEL, ARCH_KMALLOC_MINALIGN, -1); |
| |
| if (c) { |
| c->name = name; |
| c->size = size; |
| if (flags & SLAB_DESTROY_BY_RCU) { |
| /* leave room for rcu footer at the end of object */ |
| c->size += sizeof(struct slob_rcu); |
| } |
| c->flags = flags; |
| c->ctor = ctor; |
| /* ignore alignment unless it's forced */ |
| c->align = (flags & SLAB_HWCACHE_ALIGN) ? SLOB_ALIGN : 0; |
| if (c->align < ARCH_SLAB_MINALIGN) |
| c->align = ARCH_SLAB_MINALIGN; |
| if (c->align < align) |
| c->align = align; |
| } else if (flags & SLAB_PANIC) |
| panic("Cannot create slab cache %s\n", name); |
| |
| return c; |
| } |
| EXPORT_SYMBOL(kmem_cache_create); |
| |
| void kmem_cache_destroy(struct kmem_cache *c) |
| { |
| slob_free(c, sizeof(struct kmem_cache)); |
| } |
| EXPORT_SYMBOL(kmem_cache_destroy); |
| |
| void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node) |
| { |
| void *b; |
| |
| if (c->size < PAGE_SIZE) { |
| b = slob_alloc(c->size, flags, c->align, node); |
| trace_kmem_cache_alloc_node(_RET_IP_, b, c->size, |
| SLOB_UNITS(c->size) * SLOB_UNIT, |
| flags, node); |
| } else { |
| b = slob_new_pages(flags, get_order(c->size), node); |
| trace_kmem_cache_alloc_node(_RET_IP_, b, c->size, |
| PAGE_SIZE << get_order(c->size), |
| flags, node); |
| } |
| |
| if (c->ctor) |
| c->ctor(b); |
| |
| return b; |
| } |
| EXPORT_SYMBOL(kmem_cache_alloc_node); |
| |
| static void __kmem_cache_free(void *b, int size) |
| { |
| if (size < PAGE_SIZE) |
| slob_free(b, size); |
| else |
| slob_free_pages(b, get_order(size)); |
| } |
| |
| static void kmem_rcu_free(struct rcu_head *head) |
| { |
| struct slob_rcu *slob_rcu = (struct slob_rcu *)head; |
| void *b = (void *)slob_rcu - (slob_rcu->size - sizeof(struct slob_rcu)); |
| |
| __kmem_cache_free(b, slob_rcu->size); |
| } |
| |
| void kmem_cache_free(struct kmem_cache *c, void *b) |
| { |
| if (unlikely(c->flags & SLAB_DESTROY_BY_RCU)) { |
| struct slob_rcu *slob_rcu; |
| slob_rcu = b + (c->size - sizeof(struct slob_rcu)); |
| INIT_RCU_HEAD(&slob_rcu->head); |
| slob_rcu->size = c->size; |
| call_rcu(&slob_rcu->head, kmem_rcu_free); |
| } else { |
| __kmem_cache_free(b, c->size); |
| } |
| |
| trace_kmem_cache_free(_RET_IP_, b); |
| } |
| EXPORT_SYMBOL(kmem_cache_free); |
| |
| unsigned int kmem_cache_size(struct kmem_cache *c) |
| { |
| return c->size; |
| } |
| EXPORT_SYMBOL(kmem_cache_size); |
| |
| const char *kmem_cache_name(struct kmem_cache *c) |
| { |
| return c->name; |
| } |
| EXPORT_SYMBOL(kmem_cache_name); |
| |
| int kmem_cache_shrink(struct kmem_cache *d) |
| { |
| return 0; |
| } |
| EXPORT_SYMBOL(kmem_cache_shrink); |
| |
| int kmem_ptr_validate(struct kmem_cache *a, const void *b) |
| { |
| return 0; |
| } |
| |
| static unsigned int slob_ready __read_mostly; |
| |
| int slab_is_available(void) |
| { |
| return slob_ready; |
| } |
| |
| void __init kmem_cache_init(void) |
| { |
| slob_ready = 1; |
| } |