slab: do not call compound_head() in page_get_cache()

walken-google · penberg · commit 48f2474144ac · 2012-08-16T09:32:19.000+03:00
page_get_cache() does not need to call compound_head(), as its unique
caller virt_to_slab() already makes sure to return a head page.

Additionally, removing the compound_head() call makes page_get_cache()
consistent with page_get_slab().

Signed-off-by: Michel Lespinasse &lt;walken@google.com&gt;
Cc: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Cc: Pekka Enberg &lt;penberg@kernel.org&gt;
Acked-by: David Rientjes &lt;rientjes@google.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Pekka Enberg &lt;penberg@kernel.org&gt;
diff --git a/mm/slab.c b/mm/slab.c
@@ -517,7 +517,6 @@ static bool slab_max_order_set __initdata;
 
 static inline struct kmem_cache *page_get_cache(struct page *page)
 {
-	page = compound_head(page);
 	BUG_ON(!PageSlab(page));
 	return page->slab_cache;
 }

Original file line number	Diff line number	Diff line change
`@@ -517,7 +517,6 @@ static bool slab_max_order_set __initdata;`
`517`	`517`
`518`	`518`	`static inline struct kmem_cache page_get_cache(struct page page)`
`519`	`519`	`{`
`520`		`- page = compound_head(page);`
`521`	`520`	`BUG_ON(!PageSlab(page));`
`522`	`521`	`return page->slab_cache;`
`523`	`522`	`}`