Commit 1b4f59e3 authored by Glauber Costa's avatar Glauber Costa Committed by Pekka Enberg
Browse files

slub: Commonize slab_cache field in struct page 



Right now, slab and slub have fields in struct page to derive which
cache a page belongs to, but they do it slightly differently.

slab uses a field called slab_cache, that lives in the third double
word. slub, uses a field called "slab", living outside of the
doublewords area.

Ideally, we could use the same field for this. Since slub heavily makes
use of the doubleword region, there isn't really much room to move
slub's slab_cache field around. Since slab does not have such strict
placement restrictions, we can move it outside the doubleword area.

The naming used by slab, "slab_cache", is less confusing, and it is
preferred over slub's generic "slab".

Signed-off-by: default avatarGlauber Costa <glommer@parallels.com>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
CC: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>
parent b4f591c4

include/linux/mm_types.h

+2 −5
Original line number Diff line number Diff line
@@ -128,10 +128,7 @@ struct page { 
		};



		struct list_head list;	/* slobs list of pages */

		struct {		/* slab fields */

			struct kmem_cache *slab_cache;

			struct slab *slab_page;

		};

		struct slab *slab_page; /* slab fields */

	};



	/* Remainder is not double word aligned */
@@ -146,7 +143,7 @@ struct page { 
#if USE_SPLIT_PTLOCKS

		spinlock_t ptl;

#endif

		struct kmem_cache *slab;	/* SLUB: Pointer to slab */

		struct kmem_cache *slab_cache;	/* SL[AU]B: Pointer to slab */

		struct page *first_page;	/* Compound tail pages */

	};

mm/slub.c

+12 −12
Original line number Diff line number Diff line
@@ -1092,11 +1092,11 @@ static noinline struct kmem_cache_node *free_debug_processing( 
	if (!check_object(s, page, object, SLUB_RED_ACTIVE))

		goto out;



	if (unlikely(s != page->slab)) {

	if (unlikely(s != page->slab_cache)) {

		if (!PageSlab(page)) {

			slab_err(s, page, "Attempt to free object(0x%p) "

				"outside of slab", object);

		} else if (!page->slab) {

		} else if (!page->slab_cache) {

			printk(KERN_ERR

				"SLUB <none>: no slab for object 0x%p.\n",

						object);
@@ -1357,7 +1357,7 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) 
		goto out;



	inc_slabs_node(s, page_to_nid(page), page->objects);

	page->slab = s;

	page->slab_cache = s;

	__SetPageSlab(page);

	if (page->pfmemalloc)

		SetPageSlabPfmemalloc(page);
@@ -1424,7 +1424,7 @@ static void rcu_free_slab(struct rcu_head *h) 
	else

		page = container_of((struct list_head *)h, struct page, lru);



	__free_slab(page->slab, page);

	__free_slab(page->slab_cache, page);

}



static void free_slab(struct kmem_cache *s, struct page *page)
@@ -2617,9 +2617,9 @@ void kmem_cache_free(struct kmem_cache *s, void *x) 


	page = virt_to_head_page(x);



	if (kmem_cache_debug(s) && page->slab != s) {

	if (kmem_cache_debug(s) && page->slab_cache != s) {

		pr_err("kmem_cache_free: Wrong slab cache. %s but object"

			" is from  %s\n", page->slab->name, s->name);

			" is from  %s\n", page->slab_cache->name, s->name);

		WARN_ON_ONCE(1);

		return;

	}
@@ -3418,7 +3418,7 @@ size_t ksize(const void *object) 
		return PAGE_SIZE << compound_order(page);

	}



	return slab_ksize(page->slab);

	return slab_ksize(page->slab_cache);

}

EXPORT_SYMBOL(ksize);
@@ -3443,8 +3443,8 @@ bool verify_mem_not_deleted(const void *x) 
	}



	slab_lock(page);

	if (on_freelist(page->slab, page, object)) {

		object_err(page->slab, page, object, "Object is on free-list");

	if (on_freelist(page->slab_cache, page, object)) {

		object_err(page->slab_cache, page, object, "Object is on free-list");

		rv = false;

	} else {

		rv = true;
@@ -3475,7 +3475,7 @@ void kfree(const void *x) 
		__free_pages(page, compound_order(page));

		return;

	}

	slab_free(page->slab, page, object, _RET_IP_);

	slab_free(page->slab_cache, page, object, _RET_IP_);

}

EXPORT_SYMBOL(kfree);
@@ -3686,11 +3686,11 @@ static void __init kmem_cache_bootstrap_fixup(struct kmem_cache *s) 


		if (n) {

			list_for_each_entry(p, &n->partial, lru)

				p->slab = s;

				p->slab_cache = s;



#ifdef CONFIG_SLUB_DEBUG

			list_for_each_entry(p, &n->full, lru)

				p->slab = s;

				p->slab_cache = s;

#endif

		}

	}

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