[RFC PATCH 29/32] mm: Remove slab from struct page

[Vlastimil Babka <vbabka@suse.cz>]

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

All members of struct slab can now be removed from struct page.
This shrinks the definition of struct page by 30 LOC, making
it easier to understand.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 include/linux/mm_types.h   | 28 ----------------------------
 include/linux/page-flags.h | 37 -------------------------------------
 mm/slab.h                  |  4 ----
 3 files changed, 69 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index a70c292474f0..a5103cc418bc 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -107,31 +107,6 @@ struct page {
 			unsigned long dma_addr;
 			atomic_long_t pp_frag_count;
 		};
-		struct {	/* slab, slob and slub */
-			union {
-				struct list_head slab_list;
-				struct {	/* Partial pages */
-					struct page *next;
-#ifdef CONFIG_64BIT
-					int pages;	/* Nr of pages left */
-#else
-					short int pages;
-#endif
-				};
-			};
-			struct kmem_cache *slab_cache; /* not slob */
-			/* Double-word boundary */
-			void *freelist;		/* first free object */
-			union {
-				void *s_mem;	/* slab: first object */
-				unsigned long counters;		/* SLUB */
-				struct {			/* SLUB */
-					unsigned inuse:16;
-					unsigned objects:15;
-					unsigned frozen:1;
-				};
-			};
-		};
 		struct {	/* Tail pages of compound page */
 			unsigned long compound_head;	/* Bit zero is set */
 
@@ -195,9 +170,6 @@ struct page {
 		 * which are currently stored here.
 		 */
 		unsigned int page_type;
-
-		unsigned int active;		/* SLAB */
-		int units;			/* SLOB */
 	};
 
 	/* Usage count. *DO NOT USE DIRECTLY*. See page_ref.h */
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 52ec4b5e5615..481fcdcacc7a 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -909,43 +909,6 @@ extern bool is_free_buddy_page(struct page *page);
 
 __PAGEFLAG(Isolated, isolated, PF_ANY);
 
-/*
- * If network-based swap is enabled, sl*b must keep track of whether pages
- * were allocated from pfmemalloc reserves.
- */
-static inline int PageSlabPfmemalloc(struct page *page)
-{
-	VM_BUG_ON_PAGE(!PageSlab(page), page);
-	return PageActive(page);
-}
-
-/*
- * A version of PageSlabPfmemalloc() for opportunistic checks where the page
- * might have been freed under us and not be a PageSlab anymore.
- */
-static inline int __PageSlabPfmemalloc(struct page *page)
-{
-	return PageActive(page);
-}
-
-static inline void SetPageSlabPfmemalloc(struct page *page)
-{
-	VM_BUG_ON_PAGE(!PageSlab(page), page);
-	SetPageActive(page);
-}
-
-static inline void __ClearPageSlabPfmemalloc(struct page *page)
-{
-	VM_BUG_ON_PAGE(!PageSlab(page), page);
-	__ClearPageActive(page);
-}
-
-static inline void ClearPageSlabPfmemalloc(struct page *page)
-{
-	VM_BUG_ON_PAGE(!PageSlab(page), page);
-	ClearPageActive(page);
-}
-
 #ifdef CONFIG_MMU
 #define __PG_MLOCKED		(1UL << PG_mlocked)
 #else
diff --git a/mm/slab.h b/mm/slab.h
index ec2c98e882f1..58b65e5e5d49 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -47,11 +47,7 @@ struct slab {
 	static_assert(offsetof(struct page, pg) == offsetof(struct slab, sl))
 SLAB_MATCH(flags, __page_flags);
 SLAB_MATCH(compound_head, slab_list);	/* Ensure bit 0 is clear */
-SLAB_MATCH(slab_list, slab_list);
 SLAB_MATCH(rcu_head, rcu_head);
-SLAB_MATCH(slab_cache, slab_cache);
-SLAB_MATCH(s_mem, s_mem);
-SLAB_MATCH(active, active);
 SLAB_MATCH(_refcount, __page_refcount);
 #ifdef CONFIG_MEMCG
 SLAB_MATCH(memcg_data, memcg_data);
-- 
2.33.1