[PATCH 31/62] mm/slub: Convert slab freeing to struct slab

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

Improve type safety by passing a slab pointer through discard_slab()
to free_slab() and __free_slab().

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 mm/slub.c | 45 ++++++++++++++++++++++-----------------------
 1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index e3c8893f9bd5..75a411d6b76e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1964,49 +1964,48 @@ static struct slab *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
 }
 
-static void __free_slab(struct kmem_cache *s, struct page *page)
+static void __free_slab(struct kmem_cache *s, struct slab *slab)
 {
-	int order = compound_order(page);
+	struct page *page = slab_page(slab);
+	int order = slab_order(slab);
 	int pages = 1 << order;
 
 	if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) {
 		void *p;
 
-		slab_pad_check(s, page);
-		for_each_object(p, s, page_address(page),
-						page->objects)
-			check_object(s, page, p, SLUB_RED_INACTIVE);
+		slab_pad_check(s, slab_page(slab));
+		for_each_object(p, s, slab_address(slab), slab->objects)
+			check_object(s, slab_page(slab), p, SLUB_RED_INACTIVE);
 	}
 
-	__ClearPageSlabPfmemalloc(page);
+	__slab_clear_pfmemalloc(slab);
 	__ClearPageSlab(page);
-	/* In union with page->mapping where page allocator expects NULL */
-	page->slab_cache = NULL;
+	page->mapping = NULL;
 	if (current->reclaim_state)
 		current->reclaim_state->reclaimed_slab += pages;
-	unaccount_slab_page(page, order, s);
+	unaccount_slab(slab, order, s);
 	__free_pages(page, order);
 }
 
 static void rcu_free_slab(struct rcu_head *h)
 {
-	struct page *page = container_of(h, struct page, rcu_head);
+	struct slab *slab = container_of(h, struct slab, rcu_head);
 
-	__free_slab(page->slab_cache, page);
+	__free_slab(slab->slab_cache, slab);
 }
 
-static void free_slab(struct kmem_cache *s, struct page *page)
+static void free_slab(struct kmem_cache *s, struct slab *slab)
 {
 	if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
-		call_rcu(&page->rcu_head, rcu_free_slab);
+		call_rcu(&slab->rcu_head, rcu_free_slab);
 	} else
-		__free_slab(s, page);
+		__free_slab(s, slab);
 }
 
-static void discard_slab(struct kmem_cache *s, struct page *page)
+static void discard_slab(struct kmem_cache *s, struct slab *slab)
 {
-	dec_slabs_node(s, page_to_nid(page), page->objects);
-	free_slab(s, page);
+	dec_slabs_node(s, slab_nid(slab), slab->objects);
+	free_slab(s, slab);
 }
 
 /*
@@ -2431,7 +2430,7 @@ static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
 		stat(s, DEACTIVATE_FULL);
 	else if (m == M_FREE) {
 		stat(s, DEACTIVATE_EMPTY);
-		discard_slab(s, slab_page(slab));
+		discard_slab(s, slab);
 		stat(s, FREE_SLAB);
 	}
 }
@@ -2492,7 +2491,7 @@ static void __unfreeze_partials(struct kmem_cache *s, struct slab *partial_slab)
 		unusable = unusable->next;
 
 		stat(s, DEACTIVATE_EMPTY);
-		discard_slab(s, slab_page(slab));
+		discard_slab(s, slab);
 		stat(s, FREE_SLAB);
 	}
 }
@@ -3387,7 +3386,7 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab,
 
 	spin_unlock_irqrestore(&n->list_lock, flags);
 	stat(s, FREE_SLAB);
-	discard_slab(s, slab_page(slab));
+	discard_slab(s, slab);
 }
 
 /*
@@ -4257,7 +4256,7 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
 	spin_unlock_irq(&n->list_lock);
 
 	list_for_each_entry_safe(slab, h, &discard, slab_list)
-		discard_slab(s, slab_page(slab));
+		discard_slab(s, slab);
 }
 
 bool __kmem_cache_empty(struct kmem_cache *s)
@@ -4606,7 +4605,7 @@ static int __kmem_cache_do_shrink(struct kmem_cache *s)
 
 		/* Release empty slabs */
 		list_for_each_entry_safe(slab, t, &discard, slab_list)
-			discard_slab(s, slab_page(slab));
+			discard_slab(s, slab);
 
 		if (slabs_node(s, node))
 			ret = 1;
-- 
2.32.0