slab,slub: remove rcu_head size checks
rcu_head may now grow larger than list_head without affecting slab or
slub.
Link: http://lkml.kernel.org/r/20180518194519.3820-15-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/slab.c b/mm/slab.c
index c1fe809..36688f6 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1235,8 +1235,6 @@ void __init kmem_cache_init(void)
{
int i;
- BUILD_BUG_ON(sizeof(((struct page *)NULL)->lru) <
- sizeof(struct rcu_head));
kmem_cache = &kmem_cache_boot;
if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1)
diff --git a/mm/slub.c b/mm/slub.c
index a96bf42..d5bddf0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1686,17 +1686,9 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
__free_pages(page, order);
}
-#define need_reserve_slab_rcu \
- (sizeof(((struct page *)NULL)->lru) < sizeof(struct rcu_head))
-
static void rcu_free_slab(struct rcu_head *h)
{
- struct page *page;
-
- if (need_reserve_slab_rcu)
- page = virt_to_head_page(h);
- else
- page = container_of((struct list_head *)h, struct page, lru);
+ struct page *page = container_of(h, struct page, rcu_head);
__free_slab(page->slab_cache, page);
}
@@ -1704,19 +1696,7 @@ static void rcu_free_slab(struct rcu_head *h)
static void free_slab(struct kmem_cache *s, struct page *page)
{
if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
- struct rcu_head *head;
-
- if (need_reserve_slab_rcu) {
- int order = compound_order(page);
- int offset = (PAGE_SIZE << order) - s->reserved;
-
- VM_BUG_ON(s->reserved != sizeof(*head));
- head = page_address(page) + offset;
- } else {
- head = &page->rcu_head;
- }
-
- call_rcu(head, rcu_free_slab);
+ call_rcu(&page->rcu_head, rcu_free_slab);
} else
__free_slab(s, page);
}
@@ -3583,9 +3563,6 @@ static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
s->random = get_random_long();
#endif
- if (need_reserve_slab_rcu && (s->flags & SLAB_TYPESAFE_BY_RCU))
- s->reserved = sizeof(struct rcu_head);
-
if (!calculate_sizes(s, -1))
goto error;
if (disable_higher_order_debug) {
