slob: Define page struct fields used in mm_types.h

Define the fields used by slob in mm_types.h and use struct page instead
of struct slob_page in slob. This cleans up numerous of typecasts in slob.c and
makes readers aware of slob's use of page struct fields.

[Also cleans up some bitrot in slob.c. The page struct field layout
in slob.c is an old layout and does not match the one in mm_types.h]

Reviewed-by: Glauber Costa <glommer@parallels.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 37 insertions, 58 deletions

diff --git a/mm/slob.c b/mm/slob.c
index 8105be42cad1..30862a2d56a9 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -92,33 +92,12 @@ struct slob_block {
 typedef struct slob_block slob_t;
 
 /*
- * We use struct page fields to manage some slob allocation aspects,
- * however to avoid the horrible mess in include/linux/mm_types.h, we'll
- * just define our own struct page type variant here.
- */
-struct slob_page {
-        union {
-                struct {
-                        unsigned long flags;    /* mandatory */
-                        atomic_t _count;        /* mandatory */
-                        slobidx_t units;        /* free units left in page */
-                        unsigned long pad[2];
-                        slob_t *free;           /* first free slob_t in page */
-                        struct list_head list;  /* linked list of free pages */
-                };
-                struct page page;
-        };
-};
-static inline void struct_slob_page_wrong_size(void)
-{ BUILD_BUG_ON(sizeof(struct slob_page) != sizeof(struct page)); }
-
-/*
  * free_slob_page: call before a slob_page is returned to the page allocator.
  */
-static inline void free_slob_page(struct slob_page *sp)
+static inline void free_slob_page(struct page *sp)
 {
-        reset_page_mapcount(&sp->page);
-        sp->page.mapping = NULL;
+        reset_page_mapcount(sp);
+        sp->mapping = NULL;
 }
 
 /*
@@ -133,44 +112,44 @@ static LIST_HEAD(free_slob_large);
 /*
  * is_slob_page: True for all slob pages (false for bigblock pages)
  */
-static inline int is_slob_page(struct slob_page *sp)
+static inline int is_slob_page(struct page *sp)
 {
-        return PageSlab((struct page *)sp);
+        return PageSlab(sp);
 }
 
-static inline void set_slob_page(struct slob_page *sp)
+static inline void set_slob_page(struct page *sp)
 {
-        __SetPageSlab((struct page *)sp);
+        __SetPageSlab(sp);
 }
 
-static inline void clear_slob_page(struct slob_page *sp)
+static inline void clear_slob_page(struct page *sp)
 {
-        __ClearPageSlab((struct page *)sp);
+        __ClearPageSlab(sp);
 }
 
-static inline struct slob_page *slob_page(const void *addr)
+static inline struct page *slob_page(const void *addr)
 {
-        return (struct slob_page *)virt_to_page(addr);
+        return virt_to_page(addr);
 }
 
 /*
  * slob_page_free: true for pages on free_slob_pages list.
  */
-static inline int slob_page_free(struct slob_page *sp)
+static inline int slob_page_free(struct page *sp)
 {
-        return PageSlobFree((struct page *)sp);
+        return PageSlobFree(sp);
 }
 
-static void set_slob_page_free(struct slob_page *sp, struct list_head *list)
+static void set_slob_page_free(struct page *sp, struct list_head *list)
 {
         list_add(&sp->list, list);
-        __SetPageSlobFree((struct page *)sp);
+        __SetPageSlobFree(sp);
 }
 
-static inline void clear_slob_page_free(struct slob_page *sp)
+static inline void clear_slob_page_free(struct page *sp)
 {
         list_del(&sp->list);
-        __ClearPageSlobFree((struct page *)sp);
+        __ClearPageSlobFree(sp);
 }
 
 #define SLOB_UNIT sizeof(slob_t)
@@ -267,12 +246,12 @@ static void slob_free_pages(void *b, int order)
 /*
  * Allocate a slob block within a given slob_page sp.
  */
-static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)
+static void *slob_page_alloc(struct page *sp, size_t size, int align)
 {
         slob_t *prev, *cur, *aligned = NULL;
         int delta = 0, units = SLOB_UNITS(size);
 
-        for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) {
+        for (prev = NULL, cur = sp->freelist; ; prev = cur, cur = slob_next(cur)) {
                 slobidx_t avail = slob_units(cur);
 
                 if (align) {
@@ -296,12 +275,12 @@ static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)
                                 if (prev)
                                         set_slob(prev, slob_units(prev), next);
                                 else
-                                        sp->free = next;
+                                        sp->freelist = next;
                         } else { /* fragment */
                                 if (prev)
                                         set_slob(prev, slob_units(prev), cur + units);
                                 else
-                                        sp->free = cur + units;
+                                        sp->freelist = cur + units;
                                 set_slob(cur + units, avail - units, next);
                         }
 
@@ -320,7 +299,7 @@ static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)
  */
 static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
 {
-        struct slob_page *sp;
+        struct page *sp;
         struct list_head *prev;
         struct list_head *slob_list;
         slob_t *b = NULL;
@@ -341,7 +320,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
                  * If there's a node specification, search for a partial
                  * page with a matching node id in the freelist.
                  */
-                if (node != -1 && page_to_nid(&sp->page) != node)
+                if (node != -1 && page_to_nid(sp) != node)
                         continue;
 #endif
                 /* Enough room on this page? */
@@ -374,7 +353,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
 
                 spin_lock_irqsave(&slob_lock, flags);
                 sp->units = SLOB_UNITS(PAGE_SIZE);
-                sp->free = b;
+                sp->freelist = b;
                 INIT_LIST_HEAD(&sp->list);
                 set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
                 set_slob_page_free(sp, slob_list);
@@ -392,7 +371,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
  */
 static void slob_free(void *block, int size)
 {
-        struct slob_page *sp;
+        struct page *sp;
         slob_t *prev, *next, *b = (slob_t *)block;
         slobidx_t units;
         unsigned long flags;
@@ -421,7 +400,7 @@ static void slob_free(void *block, int size)
         if (!slob_page_free(sp)) {
                 /* This slob page is about to become partially free. Easy! */
                 sp->units = units;
-                sp->free = b;
+                sp->freelist = b;
                 set_slob(b, units,
                         (void *)((unsigned long)(b +
                                         SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK));
@@ -441,15 +420,15 @@ static void slob_free(void *block, int size)
          */
         sp->units += units;
 
-        if (b < sp->free) {
-                if (b + units == sp->free) {
-                        units += slob_units(sp->free);
-                        sp->free = slob_next(sp->free);
+        if (b < (slob_t *)sp->freelist) {
+                if (b + units == sp->freelist) {
+                        units += slob_units(sp->freelist);
+                        sp->freelist = slob_next(sp->freelist);
                 }
-                set_slob(b, units, sp->free);
-                sp->free = b;
+                set_slob(b, units, sp->freelist);
+                sp->freelist = b;
         } else {
-                prev = sp->free;
+                prev = sp->freelist;
                 next = slob_next(prev);
                 while (b > next) {
                         prev = next;
@@ -522,7 +501,7 @@ EXPORT_SYMBOL(__kmalloc_node);
 
 void kfree(const void *block)
 {
-        struct slob_page *sp;
+        struct page *sp;
 
         trace_kfree(_RET_IP_, block);
 
@@ -536,14 +515,14 @@ void kfree(const void *block)
                 unsigned int *m = (unsigned int *)(block - align);
                 slob_free(m, *m + align);
         } else
-                put_page(&sp->page);
+                put_page(sp);
 }
 EXPORT_SYMBOL(kfree);
 
 /* can't use ksize for kmem_cache_alloc memory, only kmalloc */
 size_t ksize(const void *block)
 {
-        struct slob_page *sp;
+        struct page *sp;
 
         BUG_ON(!block);
         if (unlikely(block == ZERO_SIZE_PTR))
@@ -555,7 +534,7 @@ size_t ksize(const void *block)
                 unsigned int *m = (unsigned int *)(block - align);
                 return SLOB_UNITS(*m) * SLOB_UNIT;
         } else
-                return sp->page.private;
+                return sp->private;
 }
 EXPORT_SYMBOL(ksize);