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>
        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++;
        }
 
        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++;
        }
 
        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++;
        }
 
         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++;
         }
 
                struct page *page = &mem_map[pfn];
 
                ClearPageReserved(page);
-               set_page_count(page, 1);
+               init_page_count(page);
                __free_page(page);
                totalram_pages++;
        }
        /* 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++;
        }
        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++;
 
        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++;
        /* 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++;
        }
 
 
 static void __meminit free_new_highpage(struct page *page)
 {
-       set_page_count(page, 1);
+       init_page_count(page);
        __free_page(page);
        totalhigh_pages++;
 }
        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++;
                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++;
        }
 
        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;
                        continue;
                page = virt_to_page(start);
                ClearPageReserved(page);
-               set_page_count(page, 1);
+               init_page_count(page);
                free_page(start);
                ++totalram_pages;
        }
 void online_page(struct page *page)
 {
        ClearPageReserved(page);
-       set_page_count(page, 1);
+       init_page_count(page);
        __free_page(page);
        totalram_pages++;
        num_physpages++;
 
        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++;
        }
        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++;
        }
 
        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++;
 
 
        /* 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;
 }
 
        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++;
        }
 
        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++;
        /* 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++;
        }
 
                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;
 
        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;
        }
 
                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;
 
                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;
 
 #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++;
        }
 
        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++;
        }
                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;
 
                                /* 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++;
                        }
 
        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++;
                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++;
 
 
        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;
                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++;
        }
 
        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++;
        }
                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++;
        }
 
 void online_page(struct page *page)
 {
        ClearPageReserved(page);
-       set_page_count(page, 1);
+       init_page_count(page);
        __free_page(page);
        totalram_pages++;
        num_physpages++;
                        struct page *page = pfn_to_page(pfn);
 
                        ClearPageReserved(page);
-                       set_page_count(page, 1);
+                       init_page_count(page);
                        __free_page(page);
                        totalhigh_pages++;
                }
 
                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);
 
 
        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;
 
        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++;
        }
                        struct page *page = mem_map + pfn;
 
                        ClearPageReserved(page);
-                       set_page_count(page, 1);
+                       init_page_count(page);
                        __free_page(page);
                        totalhigh_pages++;
                }
 
         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++;
         }
                 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++;
         }
 
        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++;
        }
        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++;
        }
 
        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++;
        }
        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++;
        }
 
 
        /* 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++;
 
        /* 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++;
 
                struct page *page = pfn_to_page(tmp);
 
                ClearPageReserved(page);
-               set_page_count(page, 1);
+               init_page_count(page);
                __free_page(page);
                totalhigh_pages++;
        }
                p = virt_to_page(addr);
 
                ClearPageReserved(p);
-               set_page_count(p, 1);
+               init_page_count(p);
                __free_page(p);
                totalram_pages++;
                num_physpages++;
                struct page *p = virt_to_page(start);
 
                ClearPageReserved(p);
-               set_page_count(p, 1);
+               init_page_count(p);
                __free_page(p);
                num_physpages++;
        }
 
                p = virt_to_page(page);
 
                ClearPageReserved(p);
-               set_page_count(p, 1);
+               init_page_count(p);
                __free_page(p);
                num_physpages++;
                totalram_pages++;
                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++;
 
        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);
        }
 }
                        (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++;
        }
 
 void online_page(struct page *page)
 {
        ClearPageReserved(page);
-       set_page_count(page, 1);
+       init_page_count(page);
        __free_page(page);
        totalram_pages++;
        num_physpages++;
        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++;
        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++;
        }
 
 {
        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++;
        }
 
                 */
                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;
 
        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)
        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);
 
 #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;
                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;
                                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);
 }
 
 
 
 #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);
 }
 
 
        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;
                        set_page_count(p, 0);
                }
 
-               set_page_refs(page, order);
+               set_page_refcounted(page);
                __free_pages(page, 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;
 }
 
        BUG_ON(PageCompound(page));
        BUG_ON(!page_count(page));
-       for (i = 1; i < (1 << order); i++) {
-               BUG_ON(page_count(page + i));
-               set_page_count(page + i, 1);
-       }
+       for (i = 1; i < (1 << order); i++)
+               set_page_refcounted(page + i);
 }
 
 /*
                        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);