summaryrefslogtreecommitdiffstats
path: root/mm/slob.c
diff options
context:
space:
mode:
authorTimothy Pearson <tpearson@raptorengineering.com>2017-08-23 14:45:25 -0500
committerTimothy Pearson <tpearson@raptorengineering.com>2017-08-23 14:45:25 -0500
commitfcbb27b0ec6dcbc5a5108cb8fb19eae64593d204 (patch)
tree22962a4387943edc841c72a4e636a068c66d58fd /mm/slob.c
downloadast2050-linux-kernel-fcbb27b0ec6dcbc5a5108cb8fb19eae64593d204.zip
ast2050-linux-kernel-fcbb27b0ec6dcbc5a5108cb8fb19eae64593d204.tar.gz
Initial import of modified Linux 2.6.28 tree
Original upstream URL: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y
Diffstat (limited to 'mm/slob.c')
-rw-r--r--mm/slob.c647
1 files changed, 647 insertions, 0 deletions
diff --git a/mm/slob.c b/mm/slob.c
new file mode 100644
index 0000000..bf7e8fc
--- /dev/null
+++ b/mm/slob.c
@@ -0,0 +1,647 @@
+/*
+ * 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 <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);
+
+/*
+ * slob_page: True for all slob pages (false for bigblock pages)
+ */
+static inline int 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);
+}
+
+/*
+ * 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_page(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);
+}
+
+/*
+ * 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 = 0;
+ 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_page(gfp & ~__GFP_ZERO, 0, node);
+ if (!b)
+ return 0;
+ sp = (struct slob_page *)virt_to_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 = (struct slob_page *)virt_to_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);
+ clear_slob_page(sp);
+ free_slob_page(sp);
+ free_page((unsigned long)b);
+ goto out;
+ }
+
+ 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);
+
+ 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;
+ return (void *)m + align;
+ } else {
+ void *ret;
+
+ ret = slob_new_page(gfp | __GFP_COMP, get_order(size), node);
+ if (ret) {
+ struct page *page;
+ page = virt_to_page(ret);
+ page->private = size;
+ }
+ return ret;
+ }
+}
+EXPORT_SYMBOL(__kmalloc_node);
+
+void kfree(const void *block)
+{
+ struct slob_page *sp;
+
+ if (unlikely(ZERO_OR_NULL_PTR(block)))
+ return;
+
+ sp = (struct slob_page *)virt_to_page(block);
+ if (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 = (struct slob_page *)virt_to_page(block);
+ if (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;
+}
+
+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);
+ else
+ b = slob_new_page(flags, get_order(c->size), 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
+ free_pages((unsigned long)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);
+ }
+}
+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;
+}
OpenPOWER on IntegriCloud