Re: [PATCHv5 1/7] mm: drop page->slab_page

From: Alexander Duyck
Date: Mon Sep 07 2015 - 01:01:18 EST


On 09/03/2015 05:35 AM, Kirill A. Shutemov wrote:
Since 8456a648cf44 ("slab: use struct page for slab management") nobody
uses slab_page field in struct page.

Let's drop it.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
include/linux/mm_types.h | 1 -
mm/slab.c | 17 +++--------------
2 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 0038ac7466fd..58620ac7f15c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -140,7 +140,6 @@ struct page {
#endif
};
- struct slab *slab_page; /* slab fields */
struct rcu_head rcu_head; /* Used by SLAB
* when destroying via RCU
*/
diff --git a/mm/slab.c b/mm/slab.c
index 200e22412a16..649044f26e5d 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

This second piece looks like it belongs in patch 2, not patch 1 based on the descriptions.

- Alex
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