[PATCH] remove set_page_count() outside mm/

set_page_count usage outside mm/ is limited to setting the refcount to 1.
Remove set_page_count from outside mm/, and replace those users with
init_page_count() and set_page_refcounted().

This allows more debug checking, and tighter control on how code is allowed
to play around with page->_count.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/alpha/mm/init.c

@@ -357,7 +357,7 @@ free_reserved_mem(void *start, void *end)
 	void *__start = start;
 	for (; __start < end; __start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(__start));
-		set_page_count(virt_to_page(__start), 1);
+		init_page_count(virt_to_page(__start));
 		free_page((long)__start);
 		totalram_pages++;
 	}

arch/arm/mm/init.c

@@ -531,7 +531,7 @@ static inline void free_area(unsigned long addr, unsigned long end, char *s)
 	for (; addr < end; addr += PAGE_SIZE) {
 		struct page *page = virt_to_page(addr);
 		ClearPageReserved(page);
-		set_page_count(page, 1);
+		init_page_count(page);
 		free_page(addr);
 		totalram_pages++;
 	}

arch/arm26/mm/init.c

@@ -324,7 +324,7 @@ static inline void free_area(unsigned long addr, unsigned long end, char *s)
 	for (; addr < end; addr += PAGE_SIZE) {
 		struct page *page = virt_to_page(addr);
 		ClearPageReserved(page);
-		set_page_count(page, 1);
+		init_page_count(page);
 		free_page(addr);
 		totalram_pages++;
 	}

arch/cris/mm/init.c

@@ -216,7 +216,7 @@ free_initmem(void)
         addr = (unsigned long)(&__init_begin);
         for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
                 ClearPageReserved(virt_to_page(addr));
-                set_page_count(virt_to_page(addr), 1);
+                init_page_count(virt_to_page(addr));
                 free_page(addr);
                 totalram_pages++;
         }

arch/frv/mm/init.c

@@ -169,7 +169,7 @@ void __init mem_init(void)
 		struct page *page = &mem_map[pfn];
 
 		ClearPageReserved(page);
-		set_page_count(page, 1);
+		init_page_count(page);
 		__free_page(page);
 		totalram_pages++;
 	}
@@ -210,7 +210,7 @@ void __init free_initmem(void)
 	/* next to check that the page we free is not a partial page */
 	for (addr = start; addr < end; addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
 	}
@@ -230,7 +230,7 @@ void __init free_initrd_mem(unsigned long start, unsigned long end)
 	int pages = 0;
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 		pages++;

arch/h8300/mm/init.c

@@ -196,7 +196,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 	int pages = 0;
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 		pages++;
@@ -219,7 +219,7 @@ free_initmem()
 	/* next to check that the page we free is not a partial page */
 	for (; addr + PAGE_SIZE < (unsigned long)(&__init_end); addr +=PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
 	}

arch/i386/mm/init.c

@@ -270,7 +270,7 @@ static void __init permanent_kmaps_init(pgd_t *pgd_base)
 
 static void __meminit free_new_highpage(struct page *page)
 {
-	set_page_count(page, 1);
+	init_page_count(page);
 	__free_page(page);
 	totalhigh_pages++;
 }
@@ -727,7 +727,7 @@ void free_initmem(void)
 	addr = (unsigned long)(&__init_begin);
 	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		memset((void *)addr, 0xcc, PAGE_SIZE);
 		free_page(addr);
 		totalram_pages++;
@@ -766,7 +766,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 		printk (KERN_INFO "Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 	}

arch/ia64/mm/init.c

@@ -197,7 +197,7 @@ free_initmem (void)
 	eaddr = (unsigned long) ia64_imva(__init_end);
 	while (addr < eaddr) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		++totalram_pages;
 		addr += PAGE_SIZE;
@@ -252,7 +252,7 @@ free_initrd_mem (unsigned long start, unsigned long end)
 			continue;
 		page = virt_to_page(start);
 		ClearPageReserved(page);
-		set_page_count(page, 1);
+		init_page_count(page);
 		free_page(start);
 		++totalram_pages;
 	}
@@ -640,7 +640,7 @@ mem_init (void)
 void online_page(struct page *page)
 {
 	ClearPageReserved(page);
-	set_page_count(page, 1);
+	init_page_count(page);
 	__free_page(page);
 	totalram_pages++;
 	num_physpages++;

arch/m32r/mm/init.c

@@ -226,7 +226,7 @@ void free_initmem(void)
 	addr = (unsigned long)(&__init_begin);
 	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
 	}
@@ -244,7 +244,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 	unsigned long p;
 	for (p = start; p < end; p += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(p));
-		set_page_count(virt_to_page(p), 1);
+		init_page_count(virt_to_page(p));
 		free_page(p);
 		totalram_pages++;
 	}

arch/m68k/mm/init.c

@@ -137,7 +137,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 	int pages = 0;
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 		pages++;

arch/m68k/mm/memory.c

@@ -54,7 +54,7 @@ void __init init_pointer_table(unsigned long ptable)
 
 	/* unreserve the page so it's possible to free that page */
 	PD_PAGE(dp)->flags &= ~(1 << PG_reserved);
-	set_page_count(PD_PAGE(dp), 1);
+	init_page_count(PD_PAGE(dp));
 
 	return;
 }

arch/m68k/mm/motorola.c

@@ -276,7 +276,7 @@ void free_initmem(void)
 	addr = (unsigned long)&__init_begin;
 	for (; addr < (unsigned long)&__init_end; addr += PAGE_SIZE) {
 		virt_to_page(addr)->flags &= ~(1 << PG_reserved);
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
 	}

arch/m68knommu/mm/init.c

@@ -195,7 +195,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 	int pages = 0;
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 		pages++;
@@ -218,7 +218,7 @@ free_initmem()
 	/* next to check that the page we free is not a partial page */
 	for (; addr + PAGE_SIZE < (unsigned long)(&__init_end); addr +=PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
 	}

arch/mips/arc/memory.c

@@ -158,7 +158,7 @@ unsigned long __init prom_free_prom_memory(void)
 		while (addr < boot_mem_map.map[i].addr
 			      + boot_mem_map.map[i].size) {
 			ClearPageReserved(virt_to_page(__va(addr)));
-			set_page_count(virt_to_page(__va(addr)), 1);
+			init_page_count(virt_to_page(__va(addr)));
 			free_page((unsigned long)__va(addr));
 			addr += PAGE_SIZE;
 			freed += PAGE_SIZE;

arch/mips/dec/prom/memory.c

@@ -118,7 +118,7 @@ unsigned long __init prom_free_prom_memory(void)
 	addr = PAGE_SIZE;
 	while (addr < end) {
 		ClearPageReserved(virt_to_page(__va(addr)));
-		set_page_count(virt_to_page(__va(addr)), 1);
+		init_page_count(virt_to_page(__va(addr)));
 		free_page((unsigned long)__va(addr));
 		addr += PAGE_SIZE;
 	}

arch/mips/mips-boards/generic/memory.c

@@ -174,7 +174,7 @@ unsigned long __init prom_free_prom_memory(void)
 		while (addr < boot_mem_map.map[i].addr
 			      + boot_mem_map.map[i].size) {
 			ClearPageReserved(virt_to_page(__va(addr)));
-			set_page_count(virt_to_page(__va(addr)), 1);
+			init_page_count(virt_to_page(__va(addr)));
 			free_page((unsigned long)__va(addr));
 			addr += PAGE_SIZE;
 			freed += PAGE_SIZE;

arch/mips/mips-boards/sim/sim_mem.c

@@ -117,7 +117,7 @@ unsigned long __init prom_free_prom_memory(void)
 		while (addr < boot_mem_map.map[i].addr
 			      + boot_mem_map.map[i].size) {
 			ClearPageReserved(virt_to_page(__va(addr)));
-			set_page_count(virt_to_page(__va(addr)), 1);
+			init_page_count(virt_to_page(__va(addr)));
 			free_page((unsigned long)__va(addr));
 			addr += PAGE_SIZE;
 			freed += PAGE_SIZE;

arch/mips/mm/init.c

@@ -245,7 +245,7 @@ void __init mem_init(void)
 #ifdef CONFIG_LIMITED_DMA
 		set_page_address(page, lowmem_page_address(page));
 #endif
-		set_page_count(page, 1);
+		init_page_count(page);
 		__free_page(page);
 		totalhigh_pages++;
 	}
@@ -292,7 +292,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 	}
@@ -315,7 +315,7 @@ void free_initmem(void)
 		page = addr;
 #endif
 		ClearPageReserved(virt_to_page(page));
-		set_page_count(virt_to_page(page), 1);
+		init_page_count(virt_to_page(page));
 		free_page(page);
 		totalram_pages++;
 		freed += PAGE_SIZE;

arch/mips/sgi-ip27/ip27-memory.c

@@ -559,7 +559,7 @@ void __init mem_init(void)
 				/* if (!page_is_ram(pgnr)) continue; */
 				/* commented out until page_is_ram works */
 				ClearPageReserved(p);
-				set_page_count(p, 1);
+				init_page_count(p);
 				__free_page(p);
 				totalram_pages++;
 			}

arch/parisc/mm/init.c

@@ -398,7 +398,7 @@ void free_initmem(void)
 	addr = (unsigned long)(&__init_begin);
 	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		num_physpages++;
 		totalram_pages++;
@@ -1018,7 +1018,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 		printk(KERN_INFO "Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		num_physpages++;
 		totalram_pages++;

arch/powerpc/mm/init_32.c

@@ -216,7 +216,7 @@ static void free_sec(unsigned long start, unsigned long end, const char *name)
 
 	while (start < end) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		cnt++;
 		start += PAGE_SIZE;
@@ -248,7 +248,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 		printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 	}

arch/powerpc/mm/init_64.c

@@ -140,7 +140,7 @@ void free_initmem(void)
 	for (; addr < (unsigned long)__init_end; addr += PAGE_SIZE) {
 		memset((void *)addr, 0xcc, PAGE_SIZE);
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
 	}
@@ -155,7 +155,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 		printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 	}

arch/powerpc/mm/mem.c

@@ -108,7 +108,7 @@ EXPORT_SYMBOL(phys_mem_access_prot);
 void online_page(struct page *page)
 {
 	ClearPageReserved(page);
-	set_page_count(page, 1);
+	init_page_count(page);
 	__free_page(page);
 	totalram_pages++;
 	num_physpages++;
@@ -376,7 +376,7 @@ void __init mem_init(void)
 			struct page *page = pfn_to_page(pfn);
 
 			ClearPageReserved(page);
-			set_page_count(page, 1);
+			init_page_count(page);
 			__free_page(page);
 			totalhigh_pages++;
 		}

arch/powerpc/platforms/cell/setup.c

@@ -115,7 +115,7 @@ static void __init cell_spuprop_present(struct device_node *spe,
 		for (pfn = start_pfn; pfn < end_pfn; pfn++) {
 			struct page *page = pfn_to_page(pfn);
 			set_page_links(page, ZONE_DMA, node_id, pfn);
-			set_page_count(page, 1);
+			init_page_count(page);
 			reset_page_mapcount(page);
 			SetPageReserved(page);
 			INIT_LIST_HEAD(&page->lru);

arch/ppc/mm/init.c

@@ -140,7 +140,7 @@ static void free_sec(unsigned long start, unsigned long end, const char *name)
 
 	while (start < end) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		cnt++;
 		start += PAGE_SIZE;
@@ -172,7 +172,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 	}
@@ -441,7 +441,7 @@ void __init mem_init(void)
 			struct page *page = mem_map + pfn;
 
 			ClearPageReserved(page);
-			set_page_count(page, 1);
+			init_page_count(page);
 			__free_page(page);
 			totalhigh_pages++;
 		}

arch/s390/mm/init.c

@@ -292,7 +292,7 @@ void free_initmem(void)
         addr = (unsigned long)(&__init_begin);
         for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
         }
@@ -307,7 +307,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
                 printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
         for (; start < end; start += PAGE_SIZE) {
                 ClearPageReserved(virt_to_page(start));
-                set_page_count(virt_to_page(start), 1);
+                init_page_count(virt_to_page(start));
                 free_page(start);
                 totalram_pages++;
         }

arch/sh/mm/init.c

@@ -273,7 +273,7 @@ void free_initmem(void)
 	addr = (unsigned long)(&__init_begin);
 	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
 	}
@@ -286,7 +286,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 	unsigned long p;
 	for (p = start; p < end; p += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(p));
-		set_page_count(virt_to_page(p), 1);
+		init_page_count(virt_to_page(p));
 		free_page(p);
 		totalram_pages++;
 	}

arch/sh64/mm/init.c

@@ -173,7 +173,7 @@ void free_initmem(void)
 	addr = (unsigned long)(&__init_begin);
 	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		free_page(addr);
 		totalram_pages++;
 	}
@@ -186,7 +186,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 	unsigned long p;
 	for (p = start; p < end; p += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(p));
-		set_page_count(virt_to_page(p), 1);
+		init_page_count(virt_to_page(p));
 		free_page(p);
 		totalram_pages++;
 	}

arch/sparc/kernel/sun4d_smp.c

@@ -266,19 +266,19 @@ void __init smp4d_boot_cpus(void)
 
 	/* Free unneeded trap tables */
 	ClearPageReserved(virt_to_page(trapbase_cpu1));
-	set_page_count(virt_to_page(trapbase_cpu1), 1);
+	init_page_count(virt_to_page(trapbase_cpu1));
 	free_page((unsigned long)trapbase_cpu1);
 	totalram_pages++;
 	num_physpages++;
 
 	ClearPageReserved(virt_to_page(trapbase_cpu2));
-	set_page_count(virt_to_page(trapbase_cpu2), 1);
+	init_page_count(virt_to_page(trapbase_cpu2));
 	free_page((unsigned long)trapbase_cpu2);
 	totalram_pages++;
 	num_physpages++;
 
 	ClearPageReserved(virt_to_page(trapbase_cpu3));
-	set_page_count(virt_to_page(trapbase_cpu3), 1);
+	init_page_count(virt_to_page(trapbase_cpu3));
 	free_page((unsigned long)trapbase_cpu3);
 	totalram_pages++;
 	num_physpages++;

arch/sparc/kernel/sun4m_smp.c

@@ -233,21 +233,21 @@ void __init smp4m_boot_cpus(void)
 	/* Free unneeded trap tables */
 	if (!cpu_isset(i, cpu_present_map)) {
 		ClearPageReserved(virt_to_page(trapbase_cpu1));
-		set_page_count(virt_to_page(trapbase_cpu1), 1);
+		init_page_count(virt_to_page(trapbase_cpu1));
 		free_page((unsigned long)trapbase_cpu1);
 		totalram_pages++;
 		num_physpages++;
 	}
 	if (!cpu_isset(2, cpu_present_map)) {
 		ClearPageReserved(virt_to_page(trapbase_cpu2));
-		set_page_count(virt_to_page(trapbase_cpu2), 1);
+		init_page_count(virt_to_page(trapbase_cpu2));
 		free_page((unsigned long)trapbase_cpu2);
 		totalram_pages++;
 		num_physpages++;
 	}
 	if (!cpu_isset(3, cpu_present_map)) {
 		ClearPageReserved(virt_to_page(trapbase_cpu3));
-		set_page_count(virt_to_page(trapbase_cpu3), 1);
+		init_page_count(virt_to_page(trapbase_cpu3));
 		free_page((unsigned long)trapbase_cpu3);
 		totalram_pages++;
 		num_physpages++;

arch/sparc/mm/init.c

@@ -383,7 +383,7 @@ void map_high_region(unsigned long start_pfn, unsigned long end_pfn)
 		struct page *page = pfn_to_page(tmp);
 
 		ClearPageReserved(page);
-		set_page_count(page, 1);
+		init_page_count(page);
 		__free_page(page);
 		totalhigh_pages++;
 	}
@@ -480,7 +480,7 @@ void free_initmem (void)
 		p = virt_to_page(addr);
 
 		ClearPageReserved(p);
-		set_page_count(p, 1);
+		init_page_count(p);
 		__free_page(p);
 		totalram_pages++;
 		num_physpages++;
@@ -497,7 +497,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 		struct page *p = virt_to_page(start);
 
 		ClearPageReserved(p);
-		set_page_count(p, 1);
+		init_page_count(p);
 		__free_page(p);
 		num_physpages++;
 	}

arch/sparc64/mm/init.c

@@ -1461,7 +1461,7 @@ void free_initmem(void)
 		p = virt_to_page(page);
 
 		ClearPageReserved(p);
-		set_page_count(p, 1);
+		init_page_count(p);
 		__free_page(p);
 		num_physpages++;
 		totalram_pages++;
@@ -1477,7 +1477,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 		struct page *p = virt_to_page(start);
 
 		ClearPageReserved(p);
-		set_page_count(p, 1);
+		init_page_count(p);
 		__free_page(p);
 		num_physpages++;
 		totalram_pages++;

arch/um/kernel/mem.c

@@ -57,7 +57,7 @@ static void setup_highmem(unsigned long highmem_start,
 	for(i = 0; i < highmem_len >> PAGE_SHIFT; i++){
 		page = &mem_map[highmem_pfn + i];
 		ClearPageReserved(page);
-		set_page_count(page, 1);
+		init_page_count(page);
 		__free_page(page);
 	}
 }
@@ -296,7 +296,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 			(end - start) >> 10);
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 	}

arch/x86_64/mm/init.c

@@ -486,7 +486,7 @@ void __init clear_kernel_mapping(unsigned long address, unsigned long size)
 void online_page(struct page *page)
 {
 	ClearPageReserved(page);
-	set_page_count(page, 1);
+	init_page_count(page);
 	__free_page(page);
 	totalram_pages++;
 	num_physpages++;
@@ -592,7 +592,7 @@ void free_initmem(void)
 	addr = (unsigned long)(&__init_begin);
 	for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(addr));
-		set_page_count(virt_to_page(addr), 1);
+		init_page_count(virt_to_page(addr));
 		memset((void *)(addr & ~(PAGE_SIZE-1)), 0xcc, PAGE_SIZE); 
 		free_page(addr);
 		totalram_pages++;
@@ -632,7 +632,7 @@ void free_initrd_mem(unsigned long start, unsigned long end)
 	printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page(start);
 		totalram_pages++;
 	}

arch/xtensa/mm/init.c

@@ -272,7 +272,7 @@ free_reserved_mem(void *start, void *end)
 {
 	for (; start < end; start += PAGE_SIZE) {
 		ClearPageReserved(virt_to_page(start));
-		set_page_count(virt_to_page(start), 1);
+		init_page_count(virt_to_page(start));
 		free_page((unsigned long)start);
 		totalram_pages++;
 	}

drivers/video/acornfb.c

@@ -1269,7 +1269,7 @@ free_unused_pages(unsigned int virtual_start, unsigned int virtual_end)
 		 */
 		page = virt_to_page(virtual_start);
 		ClearPageReserved(page);
-		set_page_count(page, 1);
+		init_page_count(page);
 		free_page(virtual_start);
 
 		virtual_start += PAGE_SIZE;

include/linux/mm.h

@@ -307,8 +307,6 @@ static inline int get_page_unless_zero(struct page *page)
 	return atomic_inc_not_zero(&page->_count);
 }
 
-#define set_page_count(p,v) 	atomic_set(&(p)->_count, (v))
-
 extern void FASTCALL(__page_cache_release(struct page *));
 
 static inline int page_count(struct page *page)
@@ -325,6 +323,15 @@ static inline void get_page(struct page *page)
 	atomic_inc(&page->_count);
 }
 
+/*
+ * Setup the page count before being freed into the page allocator for
+ * the first time (boot or memory hotplug)
+ */
+static inline void init_page_count(struct page *page)
+{
+	atomic_set(&page->_count, 1);
+}
+
 void put_page(struct page *page);
 
 void split_page(struct page *page, unsigned int order);

mm/hugetlb.c

@@ -18,6 +18,7 @@
 #include <asm/pgtable.h>
 
 #include <linux/hugetlb.h>
+#include "internal.h"
 
 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
 static unsigned long nr_huge_pages, free_huge_pages;
@@ -106,7 +107,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr)
 		return NULL;
 	}
 	spin_unlock(&hugetlb_lock);
-	set_page_count(page, 1);
+	set_page_refcounted(page);
 	for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
 		clear_user_highpage(&page[i], addr);
 	return page;
@@ -152,7 +153,7 @@ static void update_and_free_page(struct page *page)
 				1 << PG_private | 1<< PG_writeback);
 	}
 	page[1].lru.next = NULL;
-	set_page_count(page, 1);
+	set_page_refcounted(page);
 	__free_pages(page, HUGETLB_PAGE_ORDER);
 }
 

mm/internal.h

@@ -13,8 +13,19 @@
 
 #include <linux/mm.h>
 
-static inline void set_page_refs(struct page *page, int order)
+static inline void set_page_count(struct page *page, int v)
 {
+	atomic_set(&page->_count, v);
+}
+
+/*
+ * Turn a non-refcounted page (->_count == 0) into refcounted with
+ * a count of one.
+ */
+static inline void set_page_refcounted(struct page *page)
+{
+	BUG_ON(PageCompound(page) && page_private(page) != (unsigned long)page);
+	BUG_ON(atomic_read(&page->_count));
 	set_page_count(page, 1);
 }
 

mm/page_alloc.c

@@ -442,7 +442,7 @@ void fastcall __init __free_pages_bootmem(struct page *page, unsigned int order)
 	if (order == 0) {
 		__ClearPageReserved(page);
 		set_page_count(page, 0);
-		set_page_refs(page, 0);
+		set_page_refcounted(page);
 		__free_page(page);
 	} else {
 		int loop;
@@ -457,7 +457,7 @@ void fastcall __init __free_pages_bootmem(struct page *page, unsigned int order)
 			set_page_count(p, 0);
 		}
 
-		set_page_refs(page, order);
+		set_page_refcounted(page);
 		__free_pages(page, order);
 	}
 }
@@ -525,7 +525,7 @@ static int prep_new_page(struct page *page, int order)
 			1 << PG_referenced | 1 << PG_arch_1 |
 			1 << PG_checked | 1 << PG_mappedtodisk);
 	set_page_private(page, 0);
-	set_page_refs(page, order);
+	set_page_refcounted(page);
 	kernel_map_pages(page, 1 << order, 1);
 	return 0;
 }
@@ -755,10 +755,8 @@ void split_page(struct page *page, unsigned int order)
 
 	BUG_ON(PageCompound(page));
 	BUG_ON(!page_count(page));
-	for (i = 1; i < (1 << order); i++) {
+	for (i = 1; i < (1 << order); i++)
-		BUG_ON(page_count(page + i));
+		set_page_refcounted(page + i);
-		set_page_count(page + i, 1);
-	}
 }
 
 /*
@@ -1771,7 +1769,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 			continue;
 		page = pfn_to_page(pfn);
 		set_page_links(page, zone, nid, pfn);
-		set_page_count(page, 1);
+		init_page_count(page);
 		reset_page_mapcount(page);
 		SetPageReserved(page);
 		INIT_LIST_HEAD(&page->lru);