[PATCH 50/62] mm/slub: Convert slab_lock() and slab_unlock() to struct slab

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Improve type safety to the point where we can get rid of the assertions
that this is not a tail page.  Remove a lot of calls to slab_page().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/slub.c | 52 +++++++++++++++++++++++++---------------------------
 1 file changed, 25 insertions(+), 27 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 86d06f6aa743..5cf305b2b8da 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -48,7 +48,7 @@
  *   1. slab_mutex (Global Mutex)
  *   2. node->list_lock (Spinlock)
  *   3. kmem_cache->cpu_slab->lock (Local lock)
- *   4. slab_lock(page) (Only on some arches or for debugging)
+ *   4. slab_lock() (Only on some arches or for debugging)
  *   5. object_map_lock (Only for debugging)
  *
  *   slab_mutex
@@ -64,10 +64,10 @@
  *
  *   The slab_lock is only used for debugging and on arches that do not
  *   have the ability to do a cmpxchg_double. It only protects:
- *	A. page->freelist	-> List of object free in a page
- *	B. page->inuse		-> Number of objects in use
- *	C. page->objects	-> Number of objects in page
- *	D. page->frozen		-> frozen state
+ *	A. slab->freelist	-> List of object free in a page
+ *	B. slab->inuse		-> Number of objects in use
+ *	C. slab->objects	-> Number of objects in page
+ *	D. slab->frozen		-> frozen state
  *
  *   Frozen slabs
  *
@@ -417,28 +417,26 @@ static inline unsigned int oo_objects(struct kmem_cache_order_objects x)
 /*
  * Per slab locking using the pagelock
  */
-static __always_inline void __slab_lock(struct page *page)
+static __always_inline void __slab_lock(struct slab *slab)
 {
-	VM_BUG_ON_PAGE(PageTail(page), page);
-	bit_spin_lock(PG_locked, &page->flags);
+	bit_spin_lock(PG_locked, &slab->flags);
 }
 
-static __always_inline void __slab_unlock(struct page *page)
+static __always_inline void __slab_unlock(struct slab *slab)
 {
-	VM_BUG_ON_PAGE(PageTail(page), page);
-	__bit_spin_unlock(PG_locked, &page->flags);
+	__bit_spin_unlock(PG_locked, &slab->flags);
 }
 
-static __always_inline void slab_lock(struct page *page, unsigned long *flags)
+static __always_inline void slab_lock(struct slab *slab, unsigned long *flags)
 {
 	if (IS_ENABLED(CONFIG_PREEMPT_RT))
 		local_irq_save(*flags);
-	__slab_lock(page);
+	__slab_lock(slab);
 }
 
-static __always_inline void slab_unlock(struct page *page, unsigned long *flags)
+static __always_inline void slab_unlock(struct slab *slab, unsigned long *flags)
 {
-	__slab_unlock(page);
+	__slab_unlock(slab);
 	if (IS_ENABLED(CONFIG_PREEMPT_RT))
 		local_irq_restore(*flags);
 }
@@ -468,15 +466,15 @@ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct slab *slab
 		/* init to 0 to prevent spurious warnings */
 		unsigned long flags = 0;
 
-		slab_lock(slab_page(slab), &flags);
+		slab_lock(slab, &flags);
 		if (slab->freelist == freelist_old &&
 					slab->counters == counters_old) {
 			slab->freelist = freelist_new;
 			slab->counters = counters_new;
-			slab_unlock(slab_page(slab), &flags);
+			slab_unlock(slab, &flags);
 			return true;
 		}
-		slab_unlock(slab_page(slab), &flags);
+		slab_unlock(slab, &flags);
 	}
 
 	cpu_relax();
@@ -507,16 +505,16 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct slab *slab,
 		unsigned long flags;
 
 		local_irq_save(flags);
-		__slab_lock(slab_page(slab));
+		__slab_lock(slab);
 		if (slab->freelist == freelist_old &&
 					slab->counters == counters_old) {
 			slab->freelist = freelist_new;
 			slab->counters = counters_new;
-			__slab_unlock(slab_page(slab));
+			__slab_unlock(slab);
 			local_irq_restore(flags);
 			return true;
 		}
-		__slab_unlock(slab_page(slab));
+		__slab_unlock(slab);
 		local_irq_restore(flags);
 	}
 
@@ -1353,7 +1351,7 @@ static noinline int free_debug_processing(
 	int ret = 0;
 
 	spin_lock_irqsave(&n->list_lock, flags);
-	slab_lock(slab_page(slab), &flags2);
+	slab_lock(slab, &flags2);
 
 	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
 		if (!check_slab(s, slab))
@@ -1386,7 +1384,7 @@ static noinline int free_debug_processing(
 		slab_err(s, slab, "Bulk freelist count(%d) invalid(%d)\n",
 			 bulk_cnt, cnt);
 
-	slab_unlock(slab_page(slab), &flags2);
+	slab_unlock(slab, &flags2);
 	spin_unlock_irqrestore(&n->list_lock, flags);
 	if (!ret)
 		slab_fix(s, "Object at 0x%p not freed", object);
@@ -4214,7 +4212,7 @@ static void list_slab_objects(struct kmem_cache *s, struct slab *slab,
 	void *p;
 
 	slab_err(s, slab, text, s->name);
-	slab_lock(slab_page(slab), &flags);
+	slab_lock(slab, &flags);
 
 	map = get_map(s, slab);
 	for_each_object(p, s, addr, slab->objects) {
@@ -4225,7 +4223,7 @@ static void list_slab_objects(struct kmem_cache *s, struct slab *slab,
 		}
 	}
 	put_map(map);
-	slab_unlock(slab_page(slab), &flags);
+	slab_unlock(slab, &flags);
 #endif
 }
 
@@ -4958,7 +4956,7 @@ static void validate_slab(struct kmem_cache *s, struct slab *slab,
 	void *addr = slab_address(slab);
 	unsigned long flags;
 
-	slab_lock(slab_page(slab), &flags);
+	slab_lock(slab, &flags);
 
 	if (!check_slab(s, slab) || !on_freelist(s, slab, NULL))
 		goto unlock;
@@ -4973,7 +4971,7 @@ static void validate_slab(struct kmem_cache *s, struct slab *slab,
 			break;
 	}
 unlock:
-	slab_unlock(slab_page(slab), &flags);
+	slab_unlock(slab, &flags);
 }
 
 static int validate_slab_node(struct kmem_cache *s,
-- 
2.32.0