mm: properly separate the bloated ptl from the regular case

Use kernel/bounds.c to convert build-time spinlock_t size check into a
preprocessor symbol and apply that to properly separate the page::ptl
situation.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory.c b/mm/memory.c
index 24ffae2..5d9025f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4271,21 +4271,20 @@
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
 
-#if USE_SPLIT_PTE_PTLOCKS
-bool __ptlock_alloc(struct page *page)
+#if USE_SPLIT_PTE_PTLOCKS && BLOATED_SPINLOCKS
+bool ptlock_alloc(struct page *page)
 {
 	spinlock_t *ptl;
 
 	ptl = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
 	if (!ptl)
 		return false;
-	page->ptl = (unsigned long)ptl;
+	page->ptl = ptl;
 	return true;
 }
 
-void __ptlock_free(struct page *page)
+void ptlock_free(struct page *page)
 {
-	if (sizeof(spinlock_t) > sizeof(page->ptl))
-		kfree((spinlock_t *)page->ptl);
+	kfree(page->ptl);
 }
 #endif