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mm/slab: separate cache_grow() to two parts 

This is a preparation step to implement lockless allocation path when
there is no free objects in kmem_cache.

What we'd like to do here is to refill cpu cache without holding a node
lock.  To accomplish this purpose, refill should be done after new slab
allocation but before attaching the slab to the management list.  So,
this patch separates cache_grow() to two parts, allocation and attaching
to the list in order to add some code inbetween them in the following
patch.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joonsoo Kim 2016-05-19 17:10:26 -07:00 committed by Linus Torvalds
parent 511e3a0588
commit 76b342bdc7
1 changed files with 52 additions and 22 deletions
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74
mm/slab.c
View File

@ -213,6 +213,11 @@ static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list);
static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp);
static void cache_reap(struct work_struct *unused);
static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
void **list);
static inline void fixup_slab_list(struct kmem_cache *cachep,
struct kmem_cache_node *n, struct page *page,
void **list);
static int slab_early_init = 1;
#define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node))
@ -1810,7 +1815,7 @@ static size_t calculate_slab_order(struct kmem_cache *cachep,
/*
* Needed to avoid possible looping condition
* in cache_grow()
* in cache_grow_begin()
*/
if (OFF_SLAB(freelist_cache))
continue;
@ -2556,7 +2561,8 @@ static void slab_map_pages(struct kmem_cache *cache, struct page *page,
* Grow (by 1) the number of slabs within a cache. This is called by
* kmem_cache_alloc() when there are no active objs left in a cache.
*/
static int cache_grow(struct kmem_cache *cachep, gfp_t flags, int nodeid)
static struct page *cache_grow_begin(struct kmem_cache *cachep,
gfp_t flags, int nodeid)
{
void *freelist;
size_t offset;
@ -2622,21 +2628,40 @@ static int cache_grow(struct kmem_cache *cachep, gfp_t flags, int nodeid)
if (gfpflags_allow_blocking(local_flags))
local_irq_disable();
check_irq_off();
spin_lock(&n->list_lock);
/* Make slab active. */
list_add_tail(&page->lru, &(n->slabs_free));
STATS_INC_GROWN(cachep);
n->free_objects += cachep->num;
spin_unlock(&n->list_lock);
return page_node;
return page;
opps1:
kmem_freepages(cachep, page);
failed:
if (gfpflags_allow_blocking(local_flags))
local_irq_disable();
return -1;
return NULL;
}
static void cache_grow_end(struct kmem_cache *cachep, struct page *page)
{
struct kmem_cache_node *n;
void *list = NULL;
check_irq_off();
if (!page)
return;
INIT_LIST_HEAD(&page->lru);
n = get_node(cachep, page_to_nid(page));
spin_lock(&n->list_lock);
if (!page->active)
list_add_tail(&page->lru, &(n->slabs_free));
else
fixup_slab_list(cachep, n, page, &list);
STATS_INC_GROWN(cachep);
n->free_objects += cachep->num - page->active;
spin_unlock(&n->list_lock);
fixup_objfreelist_debug(cachep, &list);
}
#if DEBUG
@ -2847,6 +2872,7 @@ static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
struct array_cache *ac;
int node;
void *list = NULL;
struct page *page;
check_irq_off();
node = numa_mem_id();
@ -2874,7 +2900,6 @@ retry:
}
while (batchcount > 0) {
struct page *page;
/* Get slab alloc is to come from. */
page = get_first_slab(n, false);
if (!page)
@ -2907,8 +2932,6 @@ alloc_done:
fixup_objfreelist_debug(cachep, &list);
if (unlikely(!ac->avail)) {
int x;
/* Check if we can use obj in pfmemalloc slab */
if (sk_memalloc_socks()) {
void *obj = cache_alloc_pfmemalloc(cachep, n, flags);
@ -2917,14 +2940,18 @@ alloc_done:
return obj;
}
x = cache_grow(cachep, gfp_exact_node(flags), node);
page = cache_grow_begin(cachep, gfp_exact_node(flags), node);
cache_grow_end(cachep, page);
/* cache_grow can reenable interrupts, then ac could change. */
/*
* cache_grow_begin() can reenable interrupts,
* then ac could change.
*/
ac = cpu_cache_get(cachep);
node = numa_mem_id();
/* no objects in sight? abort */
if (x < 0 && ac->avail == 0)
if (!page && ac->avail == 0)
return NULL;
if (!ac->avail) /* objects refilled by interrupt? */
@ -3057,6 +3084,7 @@ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
struct zone *zone;
enum zone_type high_zoneidx = gfp_zone(flags);
void *obj = NULL;
struct page *page;
int nid;
unsigned int cpuset_mems_cookie;
@ -3092,8 +3120,10 @@ retry:
* We may trigger various forms of reclaim on the allowed
* set and go into memory reserves if necessary.
*/
nid = cache_grow(cache, flags, numa_mem_id());
if (nid >= 0) {
page = cache_grow_begin(cache, flags, numa_mem_id());
cache_grow_end(cache, page);
if (page) {
nid = page_to_nid(page);
obj = ____cache_alloc_node(cache,
gfp_exact_node(flags), nid);
@ -3121,7 +3151,6 @@ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
struct kmem_cache_node *n;
void *obj;
void *list = NULL;
int x;
VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES);
n = get_node(cachep, nodeid);
@ -3153,8 +3182,9 @@ retry:
must_grow:
spin_unlock(&n->list_lock);
x = cache_grow(cachep, gfp_exact_node(flags), nodeid);
if (x >= 0)
page = cache_grow_begin(cachep, gfp_exact_node(flags), nodeid);
cache_grow_end(cachep, page);
if (page)
goto retry;
return fallback_alloc(cachep, flags);