[RFC PATCH 27/32] bootmem: Use page->index instead of page->freelist

[Vlastimil Babka <vbabka@suse.cz>]

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

page->freelist is for the use of slab.  Using page->index is the same
set of bits as page->freelist, and by using an integer instead of a
pointer, we can avoid casts.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: <x86@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
 arch/x86/mm/init_64.c        | 2 +-
 include/linux/bootmem_info.h | 2 +-
 mm/bootmem_info.c            | 7 +++----
 mm/sparse.c                  | 2 +-
 4 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 36098226a957..96d34ebb20a9 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -981,7 +981,7 @@ static void __meminit free_pagetable(struct page *page, int order)
 	if (PageReserved(page)) {
 		__ClearPageReserved(page);
 
-		magic = (unsigned long)page->freelist;
+		magic = page->index;
 		if (magic == SECTION_INFO || magic == MIX_SECTION_INFO) {
 			while (nr_pages--)
 				put_page_bootmem(page++);
diff --git a/include/linux/bootmem_info.h b/include/linux/bootmem_info.h
index 2bc8b1f69c93..cc35d010fa94 100644
--- a/include/linux/bootmem_info.h
+++ b/include/linux/bootmem_info.h
@@ -30,7 +30,7 @@ void put_page_bootmem(struct page *page);
  */
 static inline void free_bootmem_page(struct page *page)
 {
-	unsigned long magic = (unsigned long)page->freelist;
+	unsigned long magic = page->index;
 
 	/*
 	 * The reserve_bootmem_region sets the reserved flag on bootmem
diff --git a/mm/bootmem_info.c b/mm/bootmem_info.c
index f03f42f426f6..f18a631e7479 100644
--- a/mm/bootmem_info.c
+++ b/mm/bootmem_info.c
@@ -15,7 +15,7 @@
 
 void get_page_bootmem(unsigned long info, struct page *page, unsigned long type)
 {
-	page->freelist = (void *)type;
+	page->index = type;
 	SetPagePrivate(page);
 	set_page_private(page, info);
 	page_ref_inc(page);
@@ -23,14 +23,13 @@ void get_page_bootmem(unsigned long info, struct page *page, unsigned long type)
 
 void put_page_bootmem(struct page *page)
 {
-	unsigned long type;
+	unsigned long type = page->index;
 
-	type = (unsigned long) page->freelist;
 	BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
 	       type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
 
 	if (page_ref_dec_return(page) == 1) {
-		page->freelist = NULL;
+		page->index = 0;
 		ClearPagePrivate(page);
 		set_page_private(page, 0);
 		INIT_LIST_HEAD(&page->lru);
diff --git a/mm/sparse.c b/mm/sparse.c
index e5c84b0cf0c9..d21c6e5910d0 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -722,7 +722,7 @@ static void free_map_bootmem(struct page *memmap)
 		>> PAGE_SHIFT;
 
 	for (i = 0; i < nr_pages; i++, page++) {
-		magic = (unsigned long) page->freelist;
+		magic = page->index;
 
 		BUG_ON(magic == NODE_INFO);
 
-- 
2.33.1