1 files changed, 696 insertions, 0 deletions

diff --git a/arch/i386/mm/init.c b/arch/i386/mm/init.c
new file mode 100644
index 000000000000..7a7ea3737265
--- /dev/null
+++ b/arch/i386/mm/init.c
@@ -0,0 +1,696 @@
+/*
+ *  linux/arch/i386/mm/init.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *
+ *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/swap.h>
+#include <linux/smp.h>
+#include <linux/init.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/bootmem.h>
+#include <linux/slab.h>
+#include <linux/proc_fs.h>
+#include <linux/efi.h>
+
+#include <asm/processor.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/dma.h>
+#include <asm/fixmap.h>
+#include <asm/e820.h>
+#include <asm/apic.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/sections.h>
+
+unsigned int __VMALLOC_RESERVE = 128 << 20;
+
+DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
+unsigned long highstart_pfn, highend_pfn;
+
+static int noinline do_test_wp_bit(void);
+
+/*
+ * Creates a middle page table and puts a pointer to it in the
+ * given global directory entry. This only returns the gd entry
+ * in non-PAE compilation mode, since the middle layer is folded.
+ */
+static pmd_t * __init one_md_table_init(pgd_t *pgd)
+{
+        pud_t *pud;
+        pmd_t *pmd_table;
+                
+#ifdef CONFIG_X86_PAE
+        pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+        set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
+        pud = pud_offset(pgd, 0);
+        if (pmd_table != pmd_offset(pud, 0)) 
+                BUG();
+#else
+        pud = pud_offset(pgd, 0);
+        pmd_table = pmd_offset(pud, 0);
+#endif
+
+        return pmd_table;
+}
+
+/*
+ * Create a page table and place a pointer to it in a middle page
+ * directory entry.
+ */
+static pte_t * __init one_page_table_init(pmd_t *pmd)
+{
+        if (pmd_none(*pmd)) {
+                pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
+                set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
+                if (page_table != pte_offset_kernel(pmd, 0))
+                        BUG();  
+
+                return page_table;
+        }
+        
+        return pte_offset_kernel(pmd, 0);
+}
+
+/*
+ * This function initializes a certain range of kernel virtual memory 
+ * with new bootmem page tables, everywhere page tables are missing in
+ * the given range.
+ */
+
+/*
+ * NOTE: The pagetables are allocated contiguous on the physical space 
+ * so we can cache the place of the first one and move around without 
+ * checking the pgd every time.
+ */
+static void __init page_table_range_init (unsigned long start, unsigned long end, pgd_t *pgd_base)
+{
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        int pgd_idx, pmd_idx;
+        unsigned long vaddr;
+
+        vaddr = start;
+        pgd_idx = pgd_index(vaddr);
+        pmd_idx = pmd_index(vaddr);
+        pgd = pgd_base + pgd_idx;
+
+        for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
+                if (pgd_none(*pgd)) 
+                        one_md_table_init(pgd);
+                pud = pud_offset(pgd, vaddr);
+                pmd = pmd_offset(pud, vaddr);
+                for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end); pmd++, pmd_idx++) {
+                        if (pmd_none(*pmd)) 
+                                one_page_table_init(pmd);
+
+                        vaddr += PMD_SIZE;
+                }
+                pmd_idx = 0;
+        }
+}
+
+static inline int is_kernel_text(unsigned long addr)
+{
+        if (addr >= PAGE_OFFSET && addr <= (unsigned long)__init_end)
+                return 1;
+        return 0;
+}
+
+/*
+ * This maps the physical memory to kernel virtual address space, a total 
+ * of max_low_pfn pages, by creating page tables starting from address 
+ * PAGE_OFFSET.
+ */
+static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
+{
+        unsigned long pfn;
+        pgd_t *pgd;
+        pmd_t *pmd;
+        pte_t *pte;
+        int pgd_idx, pmd_idx, pte_ofs;
+
+        pgd_idx = pgd_index(PAGE_OFFSET);
+        pgd = pgd_base + pgd_idx;
+        pfn = 0;
+
+        for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
+                pmd = one_md_table_init(pgd);
+                if (pfn >= max_low_pfn)
+                        continue;
+                for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD && pfn < max_low_pfn; pmd++, pmd_idx++) {
+                        unsigned int address = pfn * PAGE_SIZE + PAGE_OFFSET;
+
+                        /* Map with big pages if possible, otherwise create normal page tables. */
+                        if (cpu_has_pse) {
+                                unsigned int address2 = (pfn + PTRS_PER_PTE - 1) * PAGE_SIZE + PAGE_OFFSET + PAGE_SIZE-1;
+
+                                if (is_kernel_text(address) || is_kernel_text(address2))
+                                        set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
+                                else
+                                        set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE));
+                                pfn += PTRS_PER_PTE;
+                        } else {
+                                pte = one_page_table_init(pmd);
+
+                                for (pte_ofs = 0; pte_ofs < PTRS_PER_PTE && pfn < max_low_pfn; pte++, pfn++, pte_ofs++) {
+                                                if (is_kernel_text(address))
+                                                        set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
+                                                else
+                                                        set_pte(pte, pfn_pte(pfn, PAGE_KERNEL));
+                                }
+                        }
+                }
+        }
+}
+
+static inline int page_kills_ppro(unsigned long pagenr)
+{
+        if (pagenr >= 0x70000 && pagenr <= 0x7003F)
+                return 1;
+        return 0;
+}
+
+extern int is_available_memory(efi_memory_desc_t *);
+
+static inline int page_is_ram(unsigned long pagenr)
+{
+        int i;
+        unsigned long addr, end;
+
+        if (efi_enabled) {
+                efi_memory_desc_t *md;
+
+                for (i = 0; i < memmap.nr_map; i++) {
+                        md = &memmap.map[i];
+                        if (!is_available_memory(md))
+                                continue;
+                        addr = (md->phys_addr+PAGE_SIZE-1) >> PAGE_SHIFT;
+                        end = (md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT)) >> PAGE_SHIFT;
+
+                        if ((pagenr >= addr) && (pagenr < end))
+                                return 1;
+                }
+                return 0;
+        }
+
+        for (i = 0; i < e820.nr_map; i++) {
+
+                if (e820.map[i].type != E820_RAM)       /* not usable memory */
+                        continue;
+                /*
+                 *      !!!FIXME!!! Some BIOSen report areas as RAM that
+                 *      are not. Notably the 640->1Mb area. We need a sanity
+                 *      check here.
+                 */
+                addr = (e820.map[i].addr+PAGE_SIZE-1) >> PAGE_SHIFT;
+                end = (e820.map[i].addr+e820.map[i].size) >> PAGE_SHIFT;
+                if  ((pagenr >= addr) && (pagenr < end))
+                        return 1;
+        }
+        return 0;
+}
+
+#ifdef CONFIG_HIGHMEM
+pte_t *kmap_pte;
+pgprot_t kmap_prot;
+
+#define kmap_get_fixmap_pte(vaddr)                                      \
+        pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), vaddr), (vaddr)), (vaddr))
+
+static void __init kmap_init(void)
+{
+        unsigned long kmap_vstart;
+
+        /* cache the first kmap pte */
+        kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
+        kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
+
+        kmap_prot = PAGE_KERNEL;
+}
+
+static void __init permanent_kmaps_init(pgd_t *pgd_base)
+{
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte;
+        unsigned long vaddr;
+
+        vaddr = PKMAP_BASE;
+        page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
+
+        pgd = swapper_pg_dir + pgd_index(vaddr);
+        pud = pud_offset(pgd, vaddr);
+        pmd = pmd_offset(pud, vaddr);
+        pte = pte_offset_kernel(pmd, vaddr);
+        pkmap_page_table = pte; 
+}
+
+void __init one_highpage_init(struct page *page, int pfn, int bad_ppro)
+{
+        if (page_is_ram(pfn) && !(bad_ppro && page_kills_ppro(pfn))) {
+                ClearPageReserved(page);
+                set_bit(PG_highmem, &page->flags);
+                set_page_count(page, 1);
+                __free_page(page);
+                totalhigh_pages++;
+        } else
+                SetPageReserved(page);
+}
+
+#ifndef CONFIG_DISCONTIGMEM
+static void __init set_highmem_pages_init(int bad_ppro)
+{
+        int pfn;
+        for (pfn = highstart_pfn; pfn < highend_pfn; pfn++)
+                one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro);
+        totalram_pages += totalhigh_pages;
+}
+#else
+extern void set_highmem_pages_init(int);
+#endif /* !CONFIG_DISCONTIGMEM */
+
+#else
+#define kmap_init() do { } while (0)
+#define permanent_kmaps_init(pgd_base) do { } while (0)
+#define set_highmem_pages_init(bad_ppro) do { } while (0)
+#endif /* CONFIG_HIGHMEM */
+
+unsigned long long __PAGE_KERNEL = _PAGE_KERNEL;
+unsigned long long __PAGE_KERNEL_EXEC = _PAGE_KERNEL_EXEC;
+
+#ifndef CONFIG_DISCONTIGMEM
+#define remap_numa_kva() do {} while (0)
+#else
+extern void __init remap_numa_kva(void);
+#endif
+
+static void __init pagetable_init (void)
+{
+        unsigned long vaddr;
+        pgd_t *pgd_base = swapper_pg_dir;
+
+#ifdef CONFIG_X86_PAE
+        int i;
+        /* Init entries of the first-level page table to the zero page */
+        for (i = 0; i < PTRS_PER_PGD; i++)
+                set_pgd(pgd_base + i, __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
+#endif
+
+        /* Enable PSE if available */
+        if (cpu_has_pse) {
+                set_in_cr4(X86_CR4_PSE);
+        }
+
+        /* Enable PGE if available */
+        if (cpu_has_pge) {
+                set_in_cr4(X86_CR4_PGE);
+                __PAGE_KERNEL |= _PAGE_GLOBAL;
+                __PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;
+        }
+
+        kernel_physical_mapping_init(pgd_base);
+        remap_numa_kva();
+
+        /*
+         * Fixed mappings, only the page table structure has to be
+         * created - mappings will be set by set_fixmap():
+         */
+        vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
+        page_table_range_init(vaddr, 0, pgd_base);
+
+        permanent_kmaps_init(pgd_base);
+
+#ifdef CONFIG_X86_PAE
+        /*
+         * Add low memory identity-mappings - SMP needs it when
+         * starting up on an AP from real-mode. In the non-PAE
+         * case we already have these mappings through head.S.
+         * All user-space mappings are explicitly cleared after
+         * SMP startup.
+         */
+        pgd_base[0] = pgd_base[USER_PTRS_PER_PGD];
+#endif
+}
+
+#if defined(CONFIG_PM_DISK) || defined(CONFIG_SOFTWARE_SUSPEND)
+/*
+ * Swap suspend & friends need this for resume because things like the intel-agp
+ * driver might have split up a kernel 4MB mapping.
+ */
+char __nosavedata swsusp_pg_dir[PAGE_SIZE]
+        __attribute__ ((aligned (PAGE_SIZE)));
+
+static inline void save_pg_dir(void)
+{
+        memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE);
+}
+#else
+static inline void save_pg_dir(void)
+{
+}
+#endif
+
+void zap_low_mappings (void)
+{
+        int i;
+
+        save_pg_dir();
+
+        /*
+         * Zap initial low-memory mappings.
+         *
+         * Note that "pgd_clear()" doesn't do it for
+         * us, because pgd_clear() is a no-op on i386.
+         */
+        for (i = 0; i < USER_PTRS_PER_PGD; i++)
+#ifdef CONFIG_X86_PAE
+                set_pgd(swapper_pg_dir+i, __pgd(1 + __pa(empty_zero_page)));
+#else
+                set_pgd(swapper_pg_dir+i, __pgd(0));
+#endif
+        flush_tlb_all();
+}
+
+static int disable_nx __initdata = 0;
+u64 __supported_pte_mask = ~_PAGE_NX;
+
+/*
+ * noexec = on|off
+ *
+ * Control non executable mappings.
+ *
+ * on      Enable
+ * off     Disable
+ */
+void __init noexec_setup(const char *str)
+{
+        if (!strncmp(str, "on",2) && cpu_has_nx) {
+                __supported_pte_mask |= _PAGE_NX;
+                disable_nx = 0;
+        } else if (!strncmp(str,"off",3)) {
+                disable_nx = 1;
+                __supported_pte_mask &= ~_PAGE_NX;
+        }
+}
+
+int nx_enabled = 0;
+#ifdef CONFIG_X86_PAE
+
+static void __init set_nx(void)
+{
+        unsigned int v[4], l, h;
+
+        if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
+                cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);
+                if ((v[3] & (1 << 20)) && !disable_nx) {
+                        rdmsr(MSR_EFER, l, h);
+                        l |= EFER_NX;
+                        wrmsr(MSR_EFER, l, h);
+                        nx_enabled = 1;
+                        __supported_pte_mask |= _PAGE_NX;
+                }
+        }
+}
+
+/*
+ * Enables/disables executability of a given kernel page and
+ * returns the previous setting.
+ */
+int __init set_kernel_exec(unsigned long vaddr, int enable)
+{
+        pte_t *pte;
+        int ret = 1;
+
+        if (!nx_enabled)
+                goto out;
+
+        pte = lookup_address(vaddr);
+        BUG_ON(!pte);
+
+        if (!pte_exec_kernel(*pte))
+                ret = 0;
+
+        if (enable)
+                pte->pte_high &= ~(1 << (_PAGE_BIT_NX - 32));
+        else
+                pte->pte_high |= 1 << (_PAGE_BIT_NX - 32);
+        __flush_tlb_all();
+out:
+        return ret;
+}
+
+#endif
+
+/*
+ * paging_init() sets up the page tables - note that the first 8MB are
+ * already mapped by head.S.
+ *
+ * This routines also unmaps the page at virtual kernel address 0, so
+ * that we can trap those pesky NULL-reference errors in the kernel.
+ */
+void __init paging_init(void)
+{
+#ifdef CONFIG_X86_PAE
+        set_nx();
+        if (nx_enabled)
+                printk("NX (Execute Disable) protection: active\n");
+#endif
+
+        pagetable_init();
+
+        load_cr3(swapper_pg_dir);
+
+#ifdef CONFIG_X86_PAE
+        /*
+         * We will bail out later - printk doesn't work right now so
+         * the user would just see a hanging kernel.
+         */
+        if (cpu_has_pae)
+                set_in_cr4(X86_CR4_PAE);
+#endif
+        __flush_tlb_all();
+
+        kmap_init();
+}
+
+/*
+ * Test if the WP bit works in supervisor mode. It isn't supported on 386's
+ * and also on some strange 486's (NexGen etc.). All 586+'s are OK. This
+ * used to involve black magic jumps to work around some nasty CPU bugs,
+ * but fortunately the switch to using exceptions got rid of all that.
+ */
+
+static void __init test_wp_bit(void)
+{
+        printk("Checking if this processor honours the WP bit even in supervisor mode... ");
+
+        /* Any page-aligned address will do, the test is non-destructive */
+        __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_READONLY);
+        boot_cpu_data.wp_works_ok = do_test_wp_bit();
+        clear_fixmap(FIX_WP_TEST);
+
+        if (!boot_cpu_data.wp_works_ok) {
+                printk("No.\n");
+#ifdef CONFIG_X86_WP_WORKS_OK
+                panic("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!");
+#endif
+        } else {
+                printk("Ok.\n");
+        }
+}
+
+static void __init set_max_mapnr_init(void)
+{
+#ifdef CONFIG_HIGHMEM
+        num_physpages = highend_pfn;
+#else
+        num_physpages = max_low_pfn;
+#endif
+#ifndef CONFIG_DISCONTIGMEM
+        max_mapnr = num_physpages;
+#endif
+}
+
+static struct kcore_list kcore_mem, kcore_vmalloc; 
+
+void __init mem_init(void)
+{
+        extern int ppro_with_ram_bug(void);
+        int codesize, reservedpages, datasize, initsize;
+        int tmp;
+        int bad_ppro;
+
+#ifndef CONFIG_DISCONTIGMEM
+        if (!mem_map)
+                BUG();
+#endif
+        
+        bad_ppro = ppro_with_ram_bug();
+
+#ifdef CONFIG_HIGHMEM
+        /* check that fixmap and pkmap do not overlap */
+        if (PKMAP_BASE+LAST_PKMAP*PAGE_SIZE >= FIXADDR_START) {
+                printk(KERN_ERR "fixmap and kmap areas overlap - this will crash\n");
+                printk(KERN_ERR "pkstart: %lxh pkend: %lxh fixstart %lxh\n",
+                                PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE, FIXADDR_START);
+                BUG();
+        }
+#endif
+ 
+        set_max_mapnr_init();
+
+#ifdef CONFIG_HIGHMEM
+        high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
+#else
+        high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
+#endif
+
+        /* this will put all low memory onto the freelists */
+        totalram_pages += free_all_bootmem();
+
+        reservedpages = 0;
+        for (tmp = 0; tmp < max_low_pfn; tmp++)
+                /*
+                 * Only count reserved RAM pages
+                 */
+                if (page_is_ram(tmp) && PageReserved(pfn_to_page(tmp)))
+                        reservedpages++;
+
+        set_highmem_pages_init(bad_ppro);
+
+        codesize =  (unsigned long) &_etext - (unsigned long) &_text;
+        datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
+        initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
+
+        kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT); 
+        kclist_add(&kcore_vmalloc, (void *)VMALLOC_START, 
+                   VMALLOC_END-VMALLOC_START);
+
+        printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n",
+                (unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
+                num_physpages << (PAGE_SHIFT-10),
+                codesize >> 10,
+                reservedpages << (PAGE_SHIFT-10),
+                datasize >> 10,
+                initsize >> 10,
+                (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10))
+               );
+
+#ifdef CONFIG_X86_PAE
+        if (!cpu_has_pae)
+                panic("cannot execute a PAE-enabled kernel on a PAE-less CPU!");
+#endif
+        if (boot_cpu_data.wp_works_ok < 0)
+                test_wp_bit();
+
+        /*
+         * Subtle. SMP is doing it's boot stuff late (because it has to
+         * fork idle threads) - but it also needs low mappings for the
+         * protected-mode entry to work. We zap these entries only after
+         * the WP-bit has been tested.
+         */
+#ifndef CONFIG_SMP
+        zap_low_mappings();
+#endif
+}
+
+kmem_cache_t *pgd_cache;
+kmem_cache_t *pmd_cache;
+
+void __init pgtable_cache_init(void)
+{
+        if (PTRS_PER_PMD > 1) {
+                pmd_cache = kmem_cache_create("pmd",
+                                        PTRS_PER_PMD*sizeof(pmd_t),
+                                        PTRS_PER_PMD*sizeof(pmd_t),
+                                        0,
+                                        pmd_ctor,
+                                        NULL);
+                if (!pmd_cache)
+                        panic("pgtable_cache_init(): cannot create pmd cache");
+        }
+        pgd_cache = kmem_cache_create("pgd",
+                                PTRS_PER_PGD*sizeof(pgd_t),
+                                PTRS_PER_PGD*sizeof(pgd_t),
+                                0,
+                                pgd_ctor,
+                                PTRS_PER_PMD == 1 ? pgd_dtor : NULL);
+        if (!pgd_cache)
+                panic("pgtable_cache_init(): Cannot create pgd cache");
+}
+
+/*
+ * This function cannot be __init, since exceptions don't work in that
+ * section.  Put this after the callers, so that it cannot be inlined.
+ */
+static int noinline do_test_wp_bit(void)
+{
+        char tmp_reg;
+        int flag;
+
+        __asm__ __volatile__(
+                "       movb %0,%1      \n"
+                "1:     movb %1,%0      \n"
+                "       xorl %2,%2      \n"
+                "2:                     \n"
+                ".section __ex_table,\"a\"\n"
+                "       .align 4        \n"
+                "       .long 1b,2b     \n"
+                ".previous              \n"
+                :"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
+                 "=q" (tmp_reg),
+                 "=r" (flag)
+                :"2" (1)
+                :"memory");
+        
+        return flag;
+}
+
+void free_initmem(void)
+{
+        unsigned long addr;
+
+        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);
+                memset((void *)addr, 0xcc, PAGE_SIZE);
+                free_page(addr);
+                totalram_pages++;
+        }
+        printk (KERN_INFO "Freeing unused kernel memory: %dk freed\n", (__init_end - __init_begin) >> 10);
+}
+
+#ifdef CONFIG_BLK_DEV_INITRD
+void free_initrd_mem(unsigned long start, unsigned long end)
+{
+        if (start < 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);
+                free_page(start);
+                totalram_pages++;
+        }
+}
+#endif