Commit 8456a648 authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Pekka Enberg
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slab: use struct page for slab management



Now, there are a few field in struct slab, so we can overload these
over struct page. This will save some memory and reduce cache footprint.

After this change, slabp_cache and slab_size no longer related to
a struct slab, so rename them as freelist_cache and freelist_size.

These changes are just mechanical ones and there is no functional change.

Acked-by: default avatarAndi Kleen <ak@linux.intel.com>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: default avatarPekka Enberg <penberg@iki.fi>
parent 106a74e1
......@@ -42,18 +42,22 @@ struct page {
/* First double word block */
unsigned long flags; /* Atomic flags, some possibly
* updated asynchronously */
struct address_space *mapping; /* If low bit clear, points to
* inode address_space, or NULL.
* If page mapped as anonymous
* memory, low bit is set, and
* it points to anon_vma object:
* see PAGE_MAPPING_ANON below.
*/
union {
struct address_space *mapping; /* If low bit clear, points to
* inode address_space, or NULL.
* If page mapped as anonymous
* memory, low bit is set, and
* it points to anon_vma object:
* see PAGE_MAPPING_ANON below.
*/
void *s_mem; /* slab first object */
};
/* Second double word */
struct {
union {
pgoff_t index; /* Our offset within mapping. */
void *freelist; /* slub/slob first free object */
void *freelist; /* sl[aou]b first free object */
bool pfmemalloc; /* If set by the page allocator,
* ALLOC_NO_WATERMARKS was set
* and the low watermark was not
......@@ -109,6 +113,7 @@ struct page {
};
atomic_t _count; /* Usage count, see below. */
};
unsigned int active; /* SLAB */
};
};
......
......@@ -41,8 +41,8 @@ struct kmem_cache {
size_t colour; /* cache colouring range */
unsigned int colour_off; /* colour offset */
struct kmem_cache *slabp_cache;
unsigned int slab_size;
struct kmem_cache *freelist_cache;
unsigned int freelist_size;
/* constructor func */
void (*ctor)(void *obj);
......
......@@ -163,21 +163,6 @@
*/
static bool pfmemalloc_active __read_mostly;
/*
* struct slab
*
* Manages the objs in a slab. Placed either at the beginning of mem allocated
* for a slab, or allocated from an general cache.
* Slabs are chained into three list: fully used, partial, fully free slabs.
*/
struct slab {
struct {
struct list_head list;
void *s_mem; /* including colour offset */
unsigned int active; /* num of objs active in slab */
};
};
/*
* struct array_cache
*
......@@ -405,18 +390,10 @@ static inline struct kmem_cache *virt_to_cache(const void *obj)
return page->slab_cache;
}
static inline struct slab *virt_to_slab(const void *obj)
{
struct page *page = virt_to_head_page(obj);
VM_BUG_ON(!PageSlab(page));
return page->slab_page;
}
static inline void *index_to_obj(struct kmem_cache *cache, struct slab *slab,
static inline void *index_to_obj(struct kmem_cache *cache, struct page *page,
unsigned int idx)
{
return slab->s_mem + cache->size * idx;
return page->s_mem + cache->size * idx;
}
/*
......@@ -426,9 +403,9 @@ static inline void *index_to_obj(struct kmem_cache *cache, struct slab *slab,
* reciprocal_divide(offset, cache->reciprocal_buffer_size)
*/
static inline unsigned int obj_to_index(const struct kmem_cache *cache,
const struct slab *slab, void *obj)
const struct page *page, void *obj)
{
u32 offset = (obj - slab->s_mem);
u32 offset = (obj - page->s_mem);
return reciprocal_divide(offset, cache->reciprocal_buffer_size);
}
......@@ -590,7 +567,7 @@ static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
static size_t slab_mgmt_size(size_t nr_objs, size_t align)
{
return ALIGN(sizeof(struct slab)+nr_objs*sizeof(unsigned int), align);
return ALIGN(nr_objs * sizeof(unsigned int), align);
}
/*
......@@ -609,7 +586,6 @@ static void cache_estimate(unsigned long gfporder, size_t buffer_size,
* on it. For the latter case, the memory allocated for a
* slab is used for:
*
* - The struct slab
* - One unsigned int for each object
* - Padding to respect alignment of @align
* - @buffer_size bytes for each object
......@@ -632,8 +608,7 @@ static void cache_estimate(unsigned long gfporder, size_t buffer_size,
* into the memory allocation when taking the padding
* into account.
*/
nr_objs = (slab_size - sizeof(struct slab)) /
(buffer_size + sizeof(unsigned int));
nr_objs = (slab_size) / (buffer_size + sizeof(unsigned int));
/*
* This calculated number will be either the right
......@@ -773,11 +748,11 @@ static struct array_cache *alloc_arraycache(int node, int entries,
return nc;
}
static inline bool is_slab_pfmemalloc(struct slab *slabp)
static inline bool is_slab_pfmemalloc(struct page *page)
{
struct page *page = virt_to_page(slabp->s_mem);
struct page *mem_page = virt_to_page(page->s_mem);
return PageSlabPfmemalloc(page);
return PageSlabPfmemalloc(mem_page);
}
/* Clears pfmemalloc_active if no slabs have pfmalloc set */
......@@ -785,23 +760,23 @@ static void recheck_pfmemalloc_active(struct kmem_cache *cachep,
struct array_cache *ac)
{
struct kmem_cache_node *n = cachep->node[numa_mem_id()];
struct slab *slabp;
struct page *page;
unsigned long flags;
if (!pfmemalloc_active)
return;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(slabp, &n->slabs_full, list)
if (is_slab_pfmemalloc(slabp))
list_for_each_entry(page, &n->slabs_full, lru)
if (is_slab_pfmemalloc(page))
goto out;
list_for_each_entry(slabp, &n->slabs_partial, list)
if (is_slab_pfmemalloc(slabp))
list_for_each_entry(page, &n->slabs_partial, lru)
if (is_slab_pfmemalloc(page))
goto out;
list_for_each_entry(slabp, &n->slabs_free, list)
if (is_slab_pfmemalloc(slabp))
list_for_each_entry(page, &n->slabs_free, lru)
if (is_slab_pfmemalloc(page))
goto out;
pfmemalloc_active = false;
......@@ -841,8 +816,8 @@ static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac,
*/
n = cachep->node[numa_mem_id()];
if (!list_empty(&n->slabs_free) && force_refill) {
struct slab *slabp = virt_to_slab(objp);
ClearPageSlabPfmemalloc(virt_to_head_page(slabp->s_mem));
struct page *page = virt_to_head_page(objp);
ClearPageSlabPfmemalloc(virt_to_head_page(page->s_mem));
clear_obj_pfmemalloc(&objp);
recheck_pfmemalloc_active(cachep, ac);
return objp;
......@@ -874,9 +849,9 @@ static void *__ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac,
{
if (unlikely(pfmemalloc_active)) {
/* Some pfmemalloc slabs exist, check if this is one */
struct slab *slabp = virt_to_slab(objp);
struct page *page = virt_to_head_page(slabp->s_mem);
if (PageSlabPfmemalloc(page))
struct page *page = virt_to_head_page(objp);
struct page *mem_page = virt_to_head_page(page->s_mem);
if (PageSlabPfmemalloc(mem_page))
set_obj_pfmemalloc(&objp);
}
......@@ -1633,7 +1608,7 @@ static noinline void
slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
{
struct kmem_cache_node *n;
struct slab *slabp;
struct page *page;
unsigned long flags;
int node;
......@@ -1652,15 +1627,15 @@ slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
continue;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(slabp, &n->slabs_full, list) {
list_for_each_entry(page, &n->slabs_full, lru) {
active_objs += cachep->num;
active_slabs++;
}
list_for_each_entry(slabp, &n->slabs_partial, list) {
active_objs += slabp->active;
list_for_each_entry(page, &n->slabs_partial, lru) {
active_objs += page->active;
active_slabs++;
}
list_for_each_entry(slabp, &n->slabs_free, list)
list_for_each_entry(page, &n->slabs_free, lru)
num_slabs++;
free_objects += n->free_objects;
......@@ -1746,6 +1721,8 @@ static void kmem_freepages(struct kmem_cache *cachep, struct page *page)
BUG_ON(!PageSlab(page));
__ClearPageSlabPfmemalloc(page);
__ClearPageSlab(page);
page_mapcount_reset(page);
page->mapping = NULL;
memcg_release_pages(cachep, cachep->gfporder);
if (current->reclaim_state)
......@@ -1910,19 +1887,19 @@ static void check_poison_obj(struct kmem_cache *cachep, void *objp)
/* Print some data about the neighboring objects, if they
* exist:
*/
struct slab *slabp = virt_to_slab(objp);
struct page *page = virt_to_head_page(objp);
unsigned int objnr;
objnr = obj_to_index(cachep, slabp, objp);
objnr = obj_to_index(cachep, page, objp);
if (objnr) {
objp = index_to_obj(cachep, slabp, objnr - 1);
objp = index_to_obj(cachep, page, objnr - 1);
realobj = (char *)objp + obj_offset(cachep);
printk(KERN_ERR "Prev obj: start=%p, len=%d\n",
realobj, size);
print_objinfo(cachep, objp, 2);
}
if (objnr + 1 < cachep->num) {
objp = index_to_obj(cachep, slabp, objnr + 1);
objp = index_to_obj(cachep, page, objnr + 1);
realobj = (char *)objp + obj_offset(cachep);
printk(KERN_ERR "Next obj: start=%p, len=%d\n",
realobj, size);
......@@ -1933,11 +1910,12 @@ static void check_poison_obj(struct kmem_cache *cachep, void *objp)
#endif
#if DEBUG
static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slabp)
static void slab_destroy_debugcheck(struct kmem_cache *cachep,
struct page *page)
{
int i;
for (i = 0; i < cachep->num; i++) {
void *objp = index_to_obj(cachep, slabp, i);
void *objp = index_to_obj(cachep, page, i);
if (cachep->flags & SLAB_POISON) {
#ifdef CONFIG_DEBUG_PAGEALLOC
......@@ -1962,7 +1940,8 @@ static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slab
}
}
#else
static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slabp)
static void slab_destroy_debugcheck(struct kmem_cache *cachep,
struct page *page)
{
}
#endif
......@@ -1976,11 +1955,12 @@ static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slab
* Before calling the slab must have been unlinked from the cache. The
* cache-lock is not held/needed.
*/
static void slab_destroy(struct kmem_cache *cachep, struct slab *slabp)
static void slab_destroy(struct kmem_cache *cachep, struct page *page)
{
struct page *page = virt_to_head_page(slabp->s_mem);
struct freelist *freelist;
slab_destroy_debugcheck(cachep, slabp);
freelist = page->freelist;
slab_destroy_debugcheck(cachep, page);
if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU)) {
struct rcu_head *head;
......@@ -1998,11 +1978,11 @@ static void slab_destroy(struct kmem_cache *cachep, struct slab *slabp)
}
/*
* From now on, we don't use slab management
* From now on, we don't use freelist
* although actual page can be freed in rcu context
*/
if (OFF_SLAB(cachep))
kmem_cache_free(cachep->slabp_cache, slabp);
kmem_cache_free(cachep->freelist_cache, freelist);
}
/**
......@@ -2039,7 +2019,7 @@ static size_t calculate_slab_order(struct kmem_cache *cachep,
* use off-slab slabs. Needed to avoid a possible
* looping condition in cache_grow().
*/
offslab_limit = size - sizeof(struct slab);
offslab_limit = size;
offslab_limit /= sizeof(unsigned int);
if (num > offslab_limit)
......@@ -2162,7 +2142,7 @@ static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
int
__kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
{
size_t left_over, slab_size, ralign;
size_t left_over, freelist_size, ralign;
gfp_t gfp;
int err;
size_t size = cachep->size;
......@@ -2281,22 +2261,21 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
if (!cachep->num)
return -E2BIG;
slab_size = ALIGN(cachep->num * sizeof(unsigned int)
+ sizeof(struct slab), cachep->align);
freelist_size =
ALIGN(cachep->num * sizeof(unsigned int), cachep->align);
/*
* If the slab has been placed off-slab, and we have enough space then
* move it on-slab. This is at the expense of any extra colouring.
*/
if (flags & CFLGS_OFF_SLAB && left_over >= slab_size) {
if (flags & CFLGS_OFF_SLAB && left_over >= freelist_size) {
flags &= ~CFLGS_OFF_SLAB;
left_over -= slab_size;
left_over -= freelist_size;
}
if (flags & CFLGS_OFF_SLAB) {
/* really off slab. No need for manual alignment */
slab_size =
cachep->num * sizeof(unsigned int) + sizeof(struct slab);
freelist_size = cachep->num * sizeof(unsigned int);
#ifdef CONFIG_PAGE_POISONING
/* If we're going to use the generic kernel_map_pages()
......@@ -2313,7 +2292,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
if (cachep->colour_off < cachep->align)
cachep->colour_off = cachep->align;
cachep->colour = left_over / cachep->colour_off;
cachep->slab_size = slab_size;
cachep->freelist_size = freelist_size;
cachep->flags = flags;
cachep->allocflags = __GFP_COMP;
if (CONFIG_ZONE_DMA_FLAG && (flags & SLAB_CACHE_DMA))
......@@ -2322,7 +2301,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
cachep->reciprocal_buffer_size = reciprocal_value(size);
if (flags & CFLGS_OFF_SLAB) {
cachep->slabp_cache = kmalloc_slab(slab_size, 0u);
cachep->freelist_cache = kmalloc_slab(freelist_size, 0u);
/*
* This is a possibility for one of the malloc_sizes caches.
* But since we go off slab only for object size greater than
......@@ -2330,7 +2309,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
* this should not happen at all.
* But leave a BUG_ON for some lucky dude.
*/
BUG_ON(ZERO_OR_NULL_PTR(cachep->slabp_cache));
BUG_ON(ZERO_OR_NULL_PTR(cachep->freelist_cache));
}
err = setup_cpu_cache(cachep, gfp);
......@@ -2436,7 +2415,7 @@ static int drain_freelist(struct kmem_cache *cache,
{
struct list_head *p;
int nr_freed;
struct slab *slabp;
struct page *page;
nr_freed = 0;
while (nr_freed < tofree && !list_empty(&n->slabs_free)) {
......@@ -2448,18 +2427,18 @@ static int drain_freelist(struct kmem_cache *cache,
goto out;
}
slabp = list_entry(p, struct slab, list);
page = list_entry(p, struct page, lru);
#if DEBUG
BUG_ON(slabp->active);
BUG_ON(page->active);
#endif
list_del(&slabp->list);
list_del(&page->lru);
/*
* Safe to drop the lock. The slab is no longer linked
* to the cache.
*/
n->free_objects -= cache->num;
spin_unlock_irq(&n->list_lock);
slab_destroy(cache, slabp);
slab_destroy(cache, page);
nr_freed++;
}
out:
......@@ -2542,18 +2521,18 @@ int __kmem_cache_shutdown(struct kmem_cache *cachep)
* descriptors in kmem_cache_create, we search through the malloc_sizes array.
* If we are creating a malloc_sizes cache here it would not be visible to
* kmem_find_general_cachep till the initialization is complete.
* Hence we cannot have slabp_cache same as the original cache.
* Hence we cannot have freelist_cache same as the original cache.
*/
static struct slab *alloc_slabmgmt(struct kmem_cache *cachep,
static struct freelist *alloc_slabmgmt(struct kmem_cache *cachep,
struct page *page, int colour_off,
gfp_t local_flags, int nodeid)
{
struct slab *slabp;
struct freelist *freelist;
void *addr = page_address(page);
if (OFF_SLAB(cachep)) {
/* Slab management obj is off-slab. */
slabp = kmem_cache_alloc_node(cachep->slabp_cache,
freelist = kmem_cache_alloc_node(cachep->freelist_cache,
local_flags, nodeid);
/*
* If the first object in the slab is leaked (it's allocated
......@@ -2561,31 +2540,31 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep,
* kmemleak does not treat the ->s_mem pointer as a reference
* to the object. Otherwise we will not report the leak.
*/
kmemleak_scan_area(&slabp->list, sizeof(struct list_head),
kmemleak_scan_area(&page->lru, sizeof(struct list_head),
local_flags);
if (!slabp)
if (!freelist)
return NULL;
} else {
slabp = addr + colour_off;
colour_off += cachep->slab_size;
freelist = addr + colour_off;
colour_off += cachep->freelist_size;
}
slabp->active = 0;
slabp->s_mem = addr + colour_off;
return slabp;
page->active = 0;
page->s_mem = addr + colour_off;
return freelist;
}
static inline unsigned int *slab_bufctl(struct slab *slabp)
static inline unsigned int *slab_bufctl(struct page *page)
{
return (unsigned int *) (slabp + 1);
return (unsigned int *)(page->freelist);
}
static void cache_init_objs(struct kmem_cache *cachep,
struct slab *slabp)
struct page *page)
{
int i;
for (i = 0; i < cachep->num; i++) {
void *objp = index_to_obj(cachep, slabp, i);
void *objp = index_to_obj(cachep, page, i);
#if DEBUG
/* need to poison the objs? */
if (cachep->flags & SLAB_POISON)
......@@ -2621,7 +2600,7 @@ static void cache_init_objs(struct kmem_cache *cachep,
if (cachep->ctor)
cachep->ctor(objp);
#endif
slab_bufctl(slabp)[i] = i;
slab_bufctl(page)[i] = i;
}
}
......@@ -2635,13 +2614,13 @@ static void kmem_flagcheck(struct kmem_cache *cachep, gfp_t flags)
}
}
static void *slab_get_obj(struct kmem_cache *cachep, struct slab *slabp,
static void *slab_get_obj(struct kmem_cache *cachep, struct page *page,
int nodeid)
{
void *objp;
objp = index_to_obj(cachep, slabp, slab_bufctl(slabp)[slabp->active]);
slabp->active++;
objp = index_to_obj(cachep, page, slab_bufctl(page)[page->active]);
page->active++;
#if DEBUG
WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid);
#endif
......@@ -2649,10 +2628,10 @@ static void *slab_get_obj(struct kmem_cache *cachep, struct slab *slabp,
return objp;
}
static void slab_put_obj(struct kmem_cache *cachep, struct slab *slabp,
static void slab_put_obj(struct kmem_cache *cachep, struct page *page,
void *objp, int nodeid)
{
unsigned int objnr = obj_to_index(cachep, slabp, objp);
unsigned int objnr = obj_to_index(cachep, page, objp);
#if DEBUG
unsigned int i;
......@@ -2660,16 +2639,16 @@ static void slab_put_obj(struct kmem_cache *cachep, struct slab *slabp,
WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid);
/* Verify double free bug */
for (i = slabp->active; i < cachep->num; i++) {
if (slab_bufctl(slabp)[i] == objnr) {
for (i = page->active; i < cachep->num; i++) {
if (slab_bufctl(page)[i] == objnr) {
printk(KERN_ERR "slab: double free detected in cache "
"'%s', objp %p\n", cachep->name, objp);
BUG();
}
}
#endif
slabp->active--;
slab_bufctl(slabp)[slabp->active] = objnr;
page->active--;
slab_bufctl(page)[page->active] = objnr;
}
/*
......@@ -2677,11 +2656,11 @@ static void slab_put_obj(struct kmem_cache *cachep, struct slab *slabp,
* for the slab allocator to be able to lookup the cache and slab of a
* virtual address for kfree, ksize, and slab debugging.
*/
static void slab_map_pages(struct kmem_cache *cache, struct slab *slab,
struct page *page)
static void slab_map_pages(struct kmem_cache *cache, struct page *page,
struct freelist *freelist)
{
page->slab_cache = cache;
page->slab_page = slab;
page->freelist = freelist;
}
/*
......@@ -2691,7 +2670,7 @@ static void slab_map_pages(struct kmem_cache *cache, struct slab *slab,
static int cache_grow(struct kmem_cache *cachep,
gfp_t flags, int nodeid, struct page *page)
{
struct slab *slabp;
struct freelist *freelist;
size_t offset;
gfp_t local_flags;
struct kmem_cache_node *n;
......@@ -2738,14 +2717,14 @@ static int cache_grow(struct kmem_cache *cachep,
goto failed;
/* Get slab management. */
slabp = alloc_slabmgmt(cachep, page, offset,
freelist = alloc_slabmgmt(cachep, page, offset,
local_flags & ~GFP_CONSTRAINT_MASK, nodeid);
if (!slabp)
if (!freelist)
goto opps1;
slab_map_pages(cachep, slabp, page);
slab_map_pages(cachep, page, freelist);
cache_init_objs(cachep, slabp);
cache_init_objs(cachep, page);
if (local_flags & __GFP_WAIT)
local_irq_disable();
......@@ -2753,7 +2732,7 @@ static int cache_grow(struct kmem_cache *cachep,
spin_lock(&n->list_lock);
/* Make slab active. */
list_add_tail(&slabp->list, &(n->slabs_free));
list_add_tail(&page->lru, &(n->slabs_free));
STATS_INC_GROWN(cachep);
n->free_objects += cachep->num;
spin_unlock(&n->list_lock);
......@@ -2808,13 +2787,13 @@ static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
unsigned long caller)
{
unsigned int objnr;
struct slab *slabp;
struct page *page;
BUG_ON(virt_to_cache(objp) != cachep);
objp -= obj_offset(cachep);
kfree_debugcheck(objp);
slabp = virt_to_slab(objp);
page = virt_to_head_page(objp);
if (cachep->flags & SLAB_RED_ZONE) {
verify_redzone_free(cachep, objp);
......@@ -2824,10 +2803,10 @@ static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
if (cachep->flags & SLAB_STORE_USER)
*dbg_userword(cachep, objp) = (void *)caller;
objnr = obj_to_index(cachep, slabp, objp);
objnr = obj_to_index(cachep, page, objp);
BUG_ON(objnr >= cachep->num);
BUG_ON(objp != index_to_obj(cachep, slabp, objnr));
BUG_ON(objp != index_to_obj(cachep, page, objnr));
if (cachep->flags & SLAB_POISON) {
#ifdef CONFIG_DEBUG_PAGEALLOC
......@@ -2886,7 +2865,7 @@ retry:
while (batchcount > 0) {
struct list_head *entry;
struct slab *slabp;
struct page *page;
/* Get slab alloc is to come from. */
entry = n->slabs_partial.next;
if (entry == &n->slabs_partial) {
......@@ -2896,7 +2875,7 @@ retry:
goto