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