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Commit 213eeb9f authored by Christoph Lameter's avatar Christoph Lameter Committed by Pekka Enberg
Browse files

slub: Extract get_freelist from __slab_alloc 



get_freelist retrieves free objects from the page freelist (put there by remote
frees) or deactivates a slab page if no more objects are available.

Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarChristoph Lameter <cl@linux.com>
Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>
parent 73736e03

mm/slub.c

+32 −25
Original line number Diff line number Diff line
@@ -2126,6 +2126,37 @@ static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags, 
	return object;

}



/*

 * Check the page->freelist of a page and either transfer the freelist to the per cpu freelist

 * or deactivate the page.

 *

 * The page is still frozen if the return value is not NULL.

 *

 * If this function returns NULL then the page has been unfrozen.

 */

static inline void *get_freelist(struct kmem_cache *s, struct page *page)

{

	struct page new;

	unsigned long counters;

	void *freelist;



	do {

		freelist = page->freelist;

		counters = page->counters;

		new.counters = counters;

		VM_BUG_ON(!new.frozen);



		new.inuse = page->objects;

		new.frozen = freelist != NULL;



	} while (!cmpxchg_double_slab(s, page,

		freelist, counters,

		NULL, new.counters,

		"get_freelist"));



	return freelist;

}



/*

 * Slow path. The lockless freelist is empty or we need to perform

 * debugging duties.
@@ -2147,8 +2178,6 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, 
{

	void **object;

	unsigned long flags;

	struct page new;

	unsigned long counters;



	local_irq_save(flags);

#ifdef CONFIG_PREEMPT
@@ -2176,29 +2205,7 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, 


	stat(s, ALLOC_SLOWPATH);



	do {

		object = c->page->freelist;

		counters = c->page->counters;

		new.counters = counters;

		VM_BUG_ON(!new.frozen);



		/*

		 * If there is no object left then we use this loop to

		 * deactivate the slab which is simple since no objects

		 * are left in the slab and therefore we do not need to

		 * put the page back onto the partial list.

		 *

		 * If there are objects left then we retrieve them

		 * and use them to refill the per cpu queue.

		 */



		new.inuse = c->page->objects;

		new.frozen = object != NULL;



	} while (!__cmpxchg_double_slab(s, c->page,

			object, counters,

			NULL, new.counters,

			"__slab_alloc"));

	object = get_freelist(s, c->page);



	if (!object) {

		c->page = NULL;