slub: return object pointer from get_partial() / new_slab().
There is no need anymore to return the pointer to a slab page from get_partial() since the page reference can be stored in the kmem_cache_cpu structures "page" field. Return an object pointer instead. That in turn allows a simplification of the spaghetti code in __slab_alloc(). Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
This commit is contained in:
Christoph Lameter
Pekka Enberg
parent
acd19fd1a7
commit
497b66f2ec
137
mm/slub.c
137
mm/slub.c
@ -1554,9 +1554,11 @@ static inline void remove_partial(struct kmem_cache_node *n,
|
||||
* Lock slab, remove from the partial list and put the object into the
|
||||
* per cpu freelist.
|
||||
*
|
||||
* Returns a list of objects or NULL if it fails.
|
||||
*
|
||||
* Must hold list_lock.
|
||||
*/
|
||||
static inline int acquire_slab(struct kmem_cache *s,
|
||||
static inline void *acquire_slab(struct kmem_cache *s,
|
||||
struct kmem_cache_node *n, struct page *page,
|
||||
struct kmem_cache_cpu *c)
|
||||
{
|
||||
@ -1587,10 +1589,11 @@ static inline int acquire_slab(struct kmem_cache *s,
|
||||
|
||||
if (freelist) {
|
||||
/* Populate the per cpu freelist */
|
||||
c->freelist = freelist;
|
||||
c->page = page;
|
||||
c->node = page_to_nid(page);
|
||||
return 1;
|
||||
stat(s, ALLOC_FROM_PARTIAL);
|
||||
|
||||
return freelist;
|
||||
} else {
|
||||
/*
|
||||
* Slab page came from the wrong list. No object to allocate
|
||||
@ -1599,17 +1602,18 @@ static inline int acquire_slab(struct kmem_cache *s,
|
||||
*/
|
||||
printk(KERN_ERR "SLUB: %s : Page without available objects on"
|
||||
" partial list\n", s->name);
|
||||
return 0;
|
||||
return NULL;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Try to allocate a partial slab from a specific node.
|
||||
*/
|
||||
static struct page *get_partial_node(struct kmem_cache *s,
|
||||
static void *get_partial_node(struct kmem_cache *s,
|
||||
struct kmem_cache_node *n, struct kmem_cache_cpu *c)
|
||||
{
|
||||
struct page *page;
|
||||
void *object;
|
||||
|
||||
/*
|
||||
* Racy check. If we mistakenly see no partial slabs then we
|
||||
@ -1621,13 +1625,15 @@ static struct page *get_partial_node(struct kmem_cache *s,
|
||||
return NULL;
|
||||
|
||||
spin_lock(&n->list_lock);
|
||||
list_for_each_entry(page, &n->partial, lru)
|
||||
if (acquire_slab(s, n, page, c))
|
||||
list_for_each_entry(page, &n->partial, lru) {
|
||||
object = acquire_slab(s, n, page, c);
|
||||
if (object)
|
||||
goto out;
|
||||
page = NULL;
|
||||
}
|
||||
object = NULL;
|
||||
out:
|
||||
spin_unlock(&n->list_lock);
|
||||
return page;
|
||||
return object;
|
||||
}
|
||||
|
||||
/*
|
||||
@ -1641,7 +1647,7 @@ static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags,
|
||||
struct zoneref *z;
|
||||
struct zone *zone;
|
||||
enum zone_type high_zoneidx = gfp_zone(flags);
|
||||
struct page *page;
|
||||
void *object;
|
||||
|
||||
/*
|
||||
* The defrag ratio allows a configuration of the tradeoffs between
|
||||
@ -1674,10 +1680,10 @@ static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags,
|
||||
|
||||
if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
|
||||
n->nr_partial > s->min_partial) {
|
||||
page = get_partial_node(s, n, c);
|
||||
if (page) {
|
||||
object = get_partial_node(s, n, c);
|
||||
if (object) {
|
||||
put_mems_allowed();
|
||||
return page;
|
||||
return object;
|
||||
}
|
||||
}
|
||||
}
|
||||
@ -1689,15 +1695,15 @@ static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags,
|
||||
/*
|
||||
* Get a partial page, lock it and return it.
|
||||
*/
|
||||
static struct page *get_partial(struct kmem_cache *s, gfp_t flags, int node,
|
||||
static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
|
||||
struct kmem_cache_cpu *c)
|
||||
{
|
||||
struct page *page;
|
||||
void *object;
|
||||
int searchnode = (node == NUMA_NO_NODE) ? numa_node_id() : node;
|
||||
|
||||
page = get_partial_node(s, get_node(s, searchnode), c);
|
||||
if (page || node != NUMA_NO_NODE)
|
||||
return page;
|
||||
object = get_partial_node(s, get_node(s, searchnode), c);
|
||||
if (object || node != NUMA_NO_NODE)
|
||||
return object;
|
||||
|
||||
return get_any_partial(s, flags, c);
|
||||
}
|
||||
@ -2027,6 +2033,35 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
|
||||
}
|
||||
}
|
||||
|
||||
static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags,
|
||||
int node, struct kmem_cache_cpu **pc)
|
||||
{
|
||||
void *object;
|
||||
struct kmem_cache_cpu *c;
|
||||
struct page *page = new_slab(s, flags, node);
|
||||
|
||||
if (page) {
|
||||
c = __this_cpu_ptr(s->cpu_slab);
|
||||
if (c->page)
|
||||
flush_slab(s, c);
|
||||
|
||||
/*
|
||||
* No other reference to the page yet so we can
|
||||
* muck around with it freely without cmpxchg
|
||||
*/
|
||||
object = page->freelist;
|
||||
page->freelist = NULL;
|
||||
|
||||
stat(s, ALLOC_SLAB);
|
||||
c->node = page_to_nid(page);
|
||||
c->page = page;
|
||||
*pc = c;
|
||||
} else
|
||||
object = NULL;
|
||||
|
||||
return object;
|
||||
}
|
||||
|
||||
/*
|
||||
* Slow path. The lockless freelist is empty or we need to perform
|
||||
* debugging duties.
|
||||
@ -2049,7 +2084,6 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
|
||||
unsigned long addr, struct kmem_cache_cpu *c)
|
||||
{
|
||||
void **object;
|
||||
struct page *page;
|
||||
unsigned long flags;
|
||||
struct page new;
|
||||
unsigned long counters;
|
||||
@ -2064,8 +2098,7 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
|
||||
c = this_cpu_ptr(s->cpu_slab);
|
||||
#endif
|
||||
|
||||
page = c->page;
|
||||
if (!page)
|
||||
if (!c->page)
|
||||
goto new_slab;
|
||||
|
||||
if (unlikely(!node_match(c, node))) {
|
||||
@ -2077,8 +2110,8 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
|
||||
stat(s, ALLOC_SLOWPATH);
|
||||
|
||||
do {
|
||||
object = page->freelist;
|
||||
counters = page->counters;
|
||||
object = c->page->freelist;
|
||||
counters = c->page->counters;
|
||||
new.counters = counters;
|
||||
VM_BUG_ON(!new.frozen);
|
||||
|
||||
@ -2090,12 +2123,12 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
|
||||
*
|
||||
* If there are objects left then we retrieve them
|
||||
* and use them to refill the per cpu queue.
|
||||
*/
|
||||
*/
|
||||
|
||||
new.inuse = page->objects;
|
||||
new.inuse = c->page->objects;
|
||||
new.frozen = object != NULL;
|
||||
|
||||
} while (!__cmpxchg_double_slab(s, page,
|
||||
} while (!__cmpxchg_double_slab(s, c->page,
|
||||
object, counters,
|
||||
NULL, new.counters,
|
||||
"__slab_alloc"));
|
||||
@ -2109,53 +2142,33 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
|
||||
stat(s, ALLOC_REFILL);
|
||||
|
||||
load_freelist:
|
||||
VM_BUG_ON(!page->frozen);
|
||||
c->freelist = get_freepointer(s, object);
|
||||
c->tid = next_tid(c->tid);
|
||||
local_irq_restore(flags);
|
||||
return object;
|
||||
|
||||
new_slab:
|
||||
page = get_partial(s, gfpflags, node, c);
|
||||
if (page) {
|
||||
stat(s, ALLOC_FROM_PARTIAL);
|
||||
object = c->freelist;
|
||||
object = get_partial(s, gfpflags, node, c);
|
||||
|
||||
if (kmem_cache_debug(s))
|
||||
goto debug;
|
||||
goto load_freelist;
|
||||
if (unlikely(!object)) {
|
||||
|
||||
object = new_slab_objects(s, gfpflags, node, &c);
|
||||
|
||||
if (unlikely(!object)) {
|
||||
if (!(gfpflags & __GFP_NOWARN) && printk_ratelimit())
|
||||
slab_out_of_memory(s, gfpflags, node);
|
||||
|
||||
local_irq_restore(flags);
|
||||
return NULL;
|
||||
}
|
||||
}
|
||||
|
||||
page = new_slab(s, gfpflags, node);
|
||||
|
||||
if (page) {
|
||||
c = __this_cpu_ptr(s->cpu_slab);
|
||||
if (c->page)
|
||||
flush_slab(s, c);
|
||||
|
||||
/*
|
||||
* No other reference to the page yet so we can
|
||||
* muck around with it freely without cmpxchg
|
||||
*/
|
||||
object = page->freelist;
|
||||
page->freelist = NULL;
|
||||
|
||||
stat(s, ALLOC_SLAB);
|
||||
c->node = page_to_nid(page);
|
||||
c->page = page;
|
||||
|
||||
if (kmem_cache_debug(s))
|
||||
goto debug;
|
||||
if (likely(!kmem_cache_debug(s)))
|
||||
goto load_freelist;
|
||||
}
|
||||
if (!(gfpflags & __GFP_NOWARN) && printk_ratelimit())
|
||||
slab_out_of_memory(s, gfpflags, node);
|
||||
local_irq_restore(flags);
|
||||
return NULL;
|
||||
|
||||
debug:
|
||||
if (!object || !alloc_debug_processing(s, page, object, addr))
|
||||
goto new_slab;
|
||||
/* Only entered in the debug case */
|
||||
if (!alloc_debug_processing(s, c->page, object, addr))
|
||||
goto new_slab; /* Slab failed checks. Next slab needed */
|
||||
|
||||
c->freelist = get_freepointer(s, object);
|
||||
deactivate_slab(s, c);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user