linux-kernel - [PATCHv6 2/7] slab, slub: use page->rcu

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Date:	Tue, 15 Sep 2015 13:28:10 +0300
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>
Cc:	Andrea Arcangeli <aarcange@...hat.com>,
	Dave Hansen <dave.hansen@...el.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>,
	David Rientjes <rientjes@...gle.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Christoph Lameter <cl@...ux.com>
Subject: [PATCHv6 2/7] slab, slub: use page->rcu_head instead of page->lru plus cast

We have properly typed page->rcu_head, no need to cast page->lru.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reviewed-by: Andrea Arcangeli <aarcange@...hat.com>
Cc: Christoph Lameter <cl@...ux.com>
---
 mm/slab.c | 17 +++--------------
 mm/slub.c |  5 +----
 2 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index c77ebe6cc87c..90ba9170e0c3 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1888,21 +1888,10 @@ static void slab_destroy(struct kmem_cache *cachep, struct page *page)
 
 	freelist = page->freelist;
 	slab_destroy_debugcheck(cachep, page);
-	if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU)) {
-		struct rcu_head *head;
-
-		/*
-		 * RCU free overloads the RCU head over the LRU.
-		 * slab_page has been overloeaded over the LRU,
-		 * however it is not used from now on so that
-		 * we can use it safely.
-		 */
-		head = (void *)&page->rcu_head;
-		call_rcu(head, kmem_rcu_free);
-
-	} else {
+	if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
+		call_rcu(&page->rcu_head, kmem_rcu_free);
+	else
 		kmem_freepages(cachep, page);
-	}
 
 	/*
 	 * From now on, we don't use freelist
diff --git a/mm/slub.c b/mm/slub.c
index f614b5dc396b..6b6e771df1c7 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1507,10 +1507,7 @@ static void free_slab(struct kmem_cache *s, struct page *page)
 			VM_BUG_ON(s->reserved != sizeof(*head));
 			head = page_address(page) + offset;
 		} else {
-			/*
-			 * RCU free overloads the RCU head over the LRU
-			 */
-			head = (void *)&page->lru;
+			head = &page->rcu_head;
 		}
 
 		call_rcu(head, rcu_free_slab);
-- 
2.5.1

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