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[PATCH] slab: page mapping cleanup
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Clean up slab allocator page mapping a bit.  The memory allocated for a
slab is physically contiguous so it is okay to assume struct pages are too
so kill the long-standing comment.  Furthermore, rename set_slab_attr to
slab_map_pages and add a comment explaining why its needed.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Pekka Enberg authored and Linus Torvalds committed Jun 23, 2006
1 parent f886ed4 commit 4776874
Showing 1 changed file with 16 additions and 11 deletions.
27 changes: 16 additions & 11 deletions mm/slab.c
Original file line number Diff line number Diff line change
Expand Up @@ -2499,23 +2499,28 @@ static void slab_put_obj(struct kmem_cache *cachep, struct slab *slabp,
slabp->inuse--;
}

static void set_slab_attr(struct kmem_cache *cachep, struct slab *slabp,
void *objp)
/*
* Map pages beginning at addr to the given cache and slab. This is required
* for the slab allocator to be able to lookup the cache and slab of a
* virtual address for kfree, ksize, kmem_ptr_validate, and slab debugging.
*/
static void slab_map_pages(struct kmem_cache *cache, struct slab *slab,
void *addr)
{
int i;
int nr_pages;
struct page *page;

/* Nasty!!!!!! I hope this is OK. */
page = virt_to_page(objp);
page = virt_to_page(addr);

i = 1;
nr_pages = 1;
if (likely(!PageCompound(page)))
i <<= cachep->gfporder;
nr_pages <<= cache->gfporder;

do {
page_set_cache(page, cachep);
page_set_slab(page, slabp);
page_set_cache(page, cache);
page_set_slab(page, slab);
page++;
} while (--i);
} while (--nr_pages);
}

/*
Expand Down Expand Up @@ -2587,7 +2592,7 @@ static int cache_grow(struct kmem_cache *cachep, gfp_t flags, int nodeid)
goto opps1;

slabp->nodeid = nodeid;
set_slab_attr(cachep, slabp, objp);
slab_map_pages(cachep, slabp, objp);

cache_init_objs(cachep, slabp, ctor_flags);

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