diff options
| -rw-r--r-- | mm/slob.c | 103 |
1 files changed, 29 insertions, 74 deletions
@@ -18,9 +18,11 @@ * Above this is an implementation of kmalloc/kfree. Blocks returned * from kmalloc are 4-byte aligned and prepended with a 4-byte header. * If kmalloc is asked for objects of PAGE_SIZE or larger, it calls - * __get_free_pages directly so that it can return page-aligned blocks - * and keeps a linked list of such pages and their orders. These - * objects are detected in kfree() by their page alignment. + * __get_free_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 @@ -29,7 +31,8 @@ * alignment. Again, objects of page-size or greater are allocated by * calling __get_free_pages. As SLAB objects know their size, no separate * size bookkeeping is necessary and there is essentially no allocation - * space overhead. + * space overhead, and compound pages aren't needed for multi-page + * allocations. */ #include <linux/kernel.h> @@ -381,48 +384,26 @@ out: * End of slob allocator proper. Begin kmem_cache_alloc and kmalloc frontend. */ -struct bigblock { - int order; - void *pages; - struct bigblock *next; -}; -typedef struct bigblock bigblock_t; - -static bigblock_t *bigblocks; - -static DEFINE_SPINLOCK(block_lock); - - void *__kmalloc(size_t size, gfp_t gfp) { - slob_t *m; - bigblock_t *bb; - unsigned long flags; - if (size < PAGE_SIZE - SLOB_UNIT) { + slob_t *m; m = slob_alloc(size + SLOB_UNIT, gfp, 0); if (m) m->units = size; return m+1; + } else { + void *ret; + + ret = (void *) __get_free_pages(gfp | __GFP_COMP, + get_order(size)); + if (ret) { + struct page *page; + page = virt_to_page(ret); + page->private = size; + } + return ret; } - - bb = slob_alloc(sizeof(bigblock_t), gfp, 0); - if (!bb) - return 0; - - bb->order = get_order(size); - bb->pages = (void *)__get_free_pages(gfp, bb->order); - - if (bb->pages) { - spin_lock_irqsave(&block_lock, flags); - bb->next = bigblocks; - bigblocks = bb; - spin_unlock_irqrestore(&block_lock, flags); - return bb->pages; - } - - slob_free(bb, sizeof(bigblock_t)); - return 0; } EXPORT_SYMBOL(__kmalloc); @@ -462,59 +443,33 @@ EXPORT_SYMBOL(krealloc); void kfree(const void *block) { struct slob_page *sp; - slob_t *m; - bigblock_t *bb, **last = &bigblocks; - unsigned long flags; if (!block) return; sp = (struct slob_page *)virt_to_page(block); - if (!slob_page(sp)) { - /* on the big block list */ - spin_lock_irqsave(&block_lock, flags); - for (bb = bigblocks; bb; last = &bb->next, bb = bb->next) { - if (bb->pages == block) { - *last = bb->next; - spin_unlock_irqrestore(&block_lock, flags); - free_pages((unsigned long)block, bb->order); - slob_free(bb, sizeof(bigblock_t)); - return; - } - } - spin_unlock_irqrestore(&block_lock, flags); - WARN_ON(1); - return; - } - - m = (slob_t *)block - 1; - slob_free(m, m->units + SLOB_UNIT); - return; + if (slob_page(sp)) { + slob_t *m = (slob_t *)block - 1; + slob_free(m, m->units + SLOB_UNIT); + } 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; - bigblock_t *bb; - unsigned long flags; if (!block) return 0; sp = (struct slob_page *)virt_to_page(block); - if (!slob_page(sp)) { - spin_lock_irqsave(&block_lock, flags); - for (bb = bigblocks; bb; bb = bb->next) - if (bb->pages == block) { - spin_unlock_irqrestore(&slob_lock, flags); - return PAGE_SIZE << bb->order; - } - spin_unlock_irqrestore(&block_lock, flags); - } - - return ((slob_t *)block - 1)->units + SLOB_UNIT; + if (slob_page(sp)) + return ((slob_t *)block - 1)->units + SLOB_UNIT; + else + return sp->page.private; } struct kmem_cache { |
