[linux-2.6.git] / include / linux / mm.h

#ifndef _LINUX_MM_H
#define _LINUX_MM_H

#include <linux/sched.h>
#include <linux/errno.h>

#ifdef __KERNEL__

#include <linux/config.h>
#include <linux/gfp.h>
#include <linux/list.h>
#include <linux/mmzone.h>
#include <linux/rbtree.h>
#include <linux/fs.h>

#ifndef CONFIG_DISCONTIGMEM          /* Don't use mapnrs, do it properly */
extern unsigned long max_mapnr;
#endif

extern unsigned long num_physpages;
extern void * high_memory;
extern int page_cluster;

#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/atomic.h>

#ifndef MM_VM_SIZE
#define MM_VM_SIZE(mm)  TASK_SIZE
#endif

/*
 * Linux kernel virtual memory manager primitives.
 * The idea being to have a "virtual" mm in the same way
 * we have a virtual fs - giving a cleaner interface to the
 * mm details, and allowing different kinds of memory mappings
 * (from shared memory to executable loading to arbitrary
 * mmap() functions).
 */

/*
 * This struct defines a memory VMM memory area. There is one of these
 * per VM-area/task.  A VM area is any part of the process virtual memory
 * space that has a special rule for the page-fault handlers (ie a shared
 * library, the executable area etc).
 *
 * This structure is exactly 64 bytes on ia32.  Please think very, very hard
 * before adding anything to it.
 */
struct vm_area_struct {
        struct mm_struct * vm_mm;       /* The address space we belong to. */
        unsigned long vm_start;         /* Our start address within vm_mm. */
        unsigned long vm_end;           /* The first byte after our end address
                                           within vm_mm. */

        /* linked list of VM areas per task, sorted by address */
        struct vm_area_struct *vm_next;

        pgprot_t vm_page_prot;          /* Access permissions of this VMA. */
        unsigned long vm_flags;         /* Flags, listed below. */

        struct rb_node vm_rb;

        /*
         * For areas with an address space and backing store,
         * one of the address_space->i_mmap{,shared} lists,
         * for shm areas, the list of attaches, otherwise unused.
         */
        struct list_head shared;

        /* Function pointers to deal with this struct. */
        struct vm_operations_struct * vm_ops;

        /* Information about our backing store: */
        unsigned long vm_pgoff;         /* Offset (within vm_file) in PAGE_SIZE
                                           units, *not* PAGE_CACHE_SIZE */
        struct file * vm_file;          /* File we map to (can be NULL). */
        void * vm_private_data;         /* was vm_pte (shared mem) */
};

/*
 * vm_flags..
 */
#define VM_READ         0x00000001      /* currently active flags */
#define VM_WRITE        0x00000002
#define VM_EXEC         0x00000004
#define VM_SHARED       0x00000008

#define VM_MAYREAD      0x00000010      /* limits for mprotect() etc */
#define VM_MAYWRITE     0x00000020
#define VM_MAYEXEC      0x00000040
#define VM_MAYSHARE     0x00000080

#define VM_GROWSDOWN    0x00000100      /* general info on the segment */
#define VM_GROWSUP      0x00000200
#define VM_SHM          0x00000400      /* shared memory area, don't swap out */
#define VM_DENYWRITE    0x00000800      /* ETXTBSY on write attempts.. */

#define VM_EXECUTABLE   0x00001000
#define VM_LOCKED       0x00002000
#define VM_IO           0x00004000      /* Memory mapped I/O or similar */

                                        /* Used by sys_madvise() */
#define VM_SEQ_READ     0x00008000      /* App will access data sequentially */
#define VM_RAND_READ    0x00010000      /* App will not benefit from clustered reads */

#define VM_DONTCOPY     0x00020000      /* Do not copy this vma on fork */
#define VM_DONTEXPAND   0x00040000      /* Cannot expand with mremap() */
#define VM_RESERVED     0x00080000      /* Don't unmap it from swap_out */
#define VM_ACCOUNT      0x00100000      /* Is a VM accounted object */
#define VM_HUGETLB      0x00400000      /* Huge TLB Page VM */
#define VM_NONLINEAR    0x00800000      /* Is non-linear (remap_file_pages) */

/* It makes sense to apply VM_ACCOUNT to this vma. */
#define VM_MAYACCT(vma) (!!((vma)->vm_flags & VM_HUGETLB))

#ifndef VM_STACK_DEFAULT_FLAGS          /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
#endif

#ifdef CONFIG_STACK_GROWSUP
#define VM_STACK_FLAGS  (VM_GROWSUP | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
#else
#define VM_STACK_FLAGS  (VM_GROWSDOWN | VM_STACK_DEFAULT_FLAGS | VM_ACCOUNT)
#endif

#define VM_READHINTMASK                 (VM_SEQ_READ | VM_RAND_READ)
#define VM_ClearReadHint(v)             (v)->vm_flags &= ~VM_READHINTMASK
#define VM_NormalReadHint(v)            (!((v)->vm_flags & VM_READHINTMASK))
#define VM_SequentialReadHint(v)        ((v)->vm_flags & VM_SEQ_READ)
#define VM_RandomReadHint(v)            ((v)->vm_flags & VM_RAND_READ)

/*
 * mapping from the currently active vm_flags protection bits (the
 * low four bits) to a page protection mask..
 */
extern pgprot_t protection_map[16];


/*
 * These are the virtual MM functions - opening of an area, closing and
 * unmapping it (needed to keep files on disk up-to-date etc), pointer
 * to the functions called when a no-page or a wp-page exception occurs. 
 */
struct vm_operations_struct {
        void (*open)(struct vm_area_struct * area);
        void (*close)(struct vm_area_struct * area);
        struct page * (*nopage)(struct vm_area_struct * area, unsigned long address, int *type);
        int (*populate)(struct vm_area_struct * area, unsigned long address, unsigned long len, pgprot_t prot, unsigned long pgoff, int nonblock);
};

/* forward declaration; pte_chain is meant to be internal to rmap.c */
struct pte_chain;
struct mmu_gather;
struct inode;

#ifdef ARCH_HAS_ATOMIC_UNSIGNED
typedef unsigned page_flags_t;
#else
typedef unsigned long page_flags_t;
#endif

/*
 * Each physical page in the system has a struct page associated with
 * it to keep track of whatever it is we are using the page for at the
 * moment. Note that we have no way to track which tasks are using
 * a page.
 *
 * Try to keep the most commonly accessed fields in single cache lines
 * here (16 bytes or greater).  This ordering should be particularly
 * beneficial on 32-bit processors.
 *
 * The first line is data used in page cache lookup, the second line
 * is used for linear searches (eg. clock algorithm scans). 
 *
 * TODO: make this structure smaller, it could be as small as 32 bytes.
 */
struct page {
        page_flags_t flags;             /* atomic flags, some possibly
                                           updated asynchronously */
        atomic_t count;                 /* Usage count, see below. */
        struct address_space *mapping;  /* The inode (or ...) we belong to. */
        pgoff_t index;                  /* Our offset within mapping. */
        struct list_head lru;           /* Pageout list, eg. active_list;
                                           protected by zone->lru_lock !! */
        union {
                struct pte_chain *chain;/* Reverse pte mapping pointer.
                                         * protected by PG_chainlock */
                pte_addr_t direct;
        } pte;
        unsigned long private;          /* Mapping-private opaque data:
                                         * usually used for buffer_heads
                                         * if PagePrivate set; used for
                                         * swp_entry_t if PageSwapCache
                                         */
        /*
         * On machines where all RAM is mapped into kernel address space,
         * we can simply calculate the virtual address. On machines with
         * highmem some memory is mapped into kernel virtual memory
         * dynamically, so we need a place to store that address.
         * Note that this field could be 16 bits on x86 ... ;)
         *
         * Architectures with slow multiplication can define
         * WANT_PAGE_VIRTUAL in asm/page.h
         */
#if defined(WANT_PAGE_VIRTUAL)
        void *virtual;                  /* Kernel virtual address (NULL if
                                           not kmapped, ie. highmem) */
#endif /* WANT_PAGE_VIRTUAL */
};

/*
 * FIXME: take this include out, include page-flags.h in
 * files which need it (119 of them)
 */
#include <linux/page-flags.h>

/*
 * Methods to modify the page usage count.
 *
 * What counts for a page usage:
 * - cache mapping   (page->mapping)
 * - private data    (page->private)
 * - page mapped in a task's page tables, each mapping
 *   is counted separately
 *
 * Also, many kernel routines increase the page count before a critical
 * routine so they can be sure the page doesn't go away from under them.
 */
#define put_page_testzero(p)                            \
        ({                                              \
                BUG_ON(page_count(p) == 0);             \
                atomic_dec_and_test(&(p)->count);       \
        })

#define set_page_count(p,v)     atomic_set(&(p)->count, v)
#define __put_page(p)           atomic_dec(&(p)->count)

extern void FASTCALL(__page_cache_release(struct page *));

#ifdef CONFIG_HUGETLB_PAGE

static inline int page_count(struct page *p)
{
        if (PageCompound(p))
                p = (struct page *)p->private;
        return atomic_read(&(p)->count);
}

static inline void get_page(struct page *page)
{
        if (unlikely(PageCompound(page)))
                page = (struct page *)page->private;
        atomic_inc(&page->count);
}

void put_page(struct page *page);

#else           /* CONFIG_HUGETLB_PAGE */

#define page_count(p)           atomic_read(&(p)->count)

static inline void get_page(struct page *page)
{
        atomic_inc(&page->count);
}

static inline void put_page(struct page *page)
{
        if (!PageReserved(page) && put_page_testzero(page))
                __page_cache_release(page);
}

#endif          /* CONFIG_HUGETLB_PAGE */

/*
 * Multiple processes may "see" the same page. E.g. for untouched
 * mappings of /dev/null, all processes see the same page full of
 * zeroes, and text pages of executables and shared libraries have
 * only one copy in memory, at most, normally.
 *
 * For the non-reserved pages, page->count denotes a reference count.
 *   page->count == 0 means the page is free.
 *   page->count == 1 means the page is used for exactly one purpose
 *   (e.g. a private data page of one process).
 *
 * A page may be used for kmalloc() or anyone else who does a
 * __get_free_page(). In this case the page->count is at least 1, and
 * all other fields are unused but should be 0 or NULL. The
 * management of this page is the responsibility of the one who uses
 * it.
 *
 * The other pages (we may call them "process pages") are completely
 * managed by the Linux memory manager: I/O, buffers, swapping etc.
 * The following discussion applies only to them.
 *
 * A page may belong to an inode's memory mapping. In this case,
 * page->mapping is the pointer to the inode, and page->index is the
 * file offset of the page, in units of PAGE_CACHE_SIZE.
 *
 * A page contains an opaque `private' member, which belongs to the
 * page's address_space.  Usually, this is the address of a circular
 * list of the page's disk buffers.
 *
 * For pages belonging to inodes, the page->count is the number of
 * attaches, plus 1 if `private' contains something, plus one for
 * the page cache itself.
 *
 * All pages belonging to an inode are in these doubly linked lists:
 * mapping->clean_pages, mapping->dirty_pages and mapping->locked_pages;
 * using the page->list list_head. These fields are also used for
 * freelist managemet (when page->count==0).
 *
 * There is also a per-mapping radix tree mapping index to the page
 * in memory if present. The tree is rooted at mapping->root.  
 *
 * All process pages can do I/O:
 * - inode pages may need to be read from disk,
 * - inode pages which have been modified and are MAP_SHARED may need
 *   to be written to disk,
 * - private pages which have been modified may need to be swapped out
 *   to swap space and (later) to be read back into memory.
 */

/*
 * The zone field is never updated after free_area_init_core()
 * sets it, so none of the operations on it need to be atomic.
 * We'll have up to (MAX_NUMNODES * MAX_NR_ZONES) zones total,
 * so we use (MAX_NODES_SHIFT + MAX_ZONES_SHIFT) here to get enough bits.
 */
#define NODEZONE_SHIFT (sizeof(page_flags_t)*8 - MAX_NODES_SHIFT - MAX_ZONES_SHIFT)
#define NODEZONE(node, zone)    ((node << ZONES_SHIFT) | zone)

static inline unsigned long page_zonenum(struct page *page)
{
        return (page->flags >> NODEZONE_SHIFT) & (~(~0UL << ZONES_SHIFT));
}
static inline unsigned long page_to_nid(struct page *page)
{
        return (page->flags >> (NODEZONE_SHIFT + ZONES_SHIFT));
}

struct zone;
extern struct zone *zone_table[];

static inline struct zone *page_zone(struct page *page)
{
        return zone_table[page->flags >> NODEZONE_SHIFT];
}

static inline void set_page_zone(struct page *page, unsigned long nodezone_num)
{
        page->flags &= ~(~0UL << NODEZONE_SHIFT);
        page->flags |= nodezone_num << NODEZONE_SHIFT;
}

#ifndef CONFIG_DISCONTIGMEM
/* The array of struct pages - for discontigmem use pgdat->lmem_map */
extern struct page *mem_map;
#endif

static inline void *lowmem_page_address(struct page *page)
{
        return __va(page_to_pfn(page) << PAGE_SHIFT);
}

#if defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL)
#define HASHED_PAGE_VIRTUAL
#endif

#if defined(WANT_PAGE_VIRTUAL)
#define page_address(page) ((page)->virtual)
#define set_page_address(page, address)                 \
        do {                                            \
                (page)->virtual = (address);            \
        } while(0)
#define page_address_init()  do { } while(0)
#endif

#if defined(HASHED_PAGE_VIRTUAL)
void *page_address(struct page *page);
void set_page_address(struct page *page, void *virtual);
void page_address_init(void);
#endif

#if !defined(HASHED_PAGE_VIRTUAL) && !defined(WANT_PAGE_VIRTUAL)
#define page_address(page) lowmem_page_address(page)
#define set_page_address(page, address)  do { } while(0)
#define page_address_init()  do { } while(0)
#endif

/*
 * On an anonymous page mapped into a user virtual memory area,
 * page->mapping points to its anon_vma, not to a struct address_space.
 *
 * Please note that, confusingly, "page_mapping" refers to the inode
 * address_space which maps the page from disk; whereas "page_mapped"
 * refers to user virtual address space into which the page is mapped.
 */
static inline struct address_space *page_mapping(struct page *page)
{
        return PageAnon(page)? NULL: page->mapping;
}

/*
 * Return true if this page is mapped into pagetables.  Subtle: test pte.direct
 * rather than pte.chain.  Because sometimes pte.direct is 64-bit, and .chain
 * is only 32-bit.
 */
static inline int page_mapped(struct page *page)
{
        return page->pte.direct != 0;
}

/*
 * Error return values for the *_nopage functions
 */
#define NOPAGE_SIGBUS   (NULL)
#define NOPAGE_OOM      ((struct page *) (-1))

/*
 * Different kinds of faults, as returned by handle_mm_fault().
 * Used to decide whether a process gets delivered SIGBUS or
 * just gets major/minor fault counters bumped up.
 */
#define VM_FAULT_OOM    (-1)
#define VM_FAULT_SIGBUS 0
#define VM_FAULT_MINOR  1
#define VM_FAULT_MAJOR  2

#define offset_in_page(p)       ((unsigned long)(p) & ~PAGE_MASK)

extern void show_free_areas(void);

struct page *shmem_nopage(struct vm_area_struct * vma,
                        unsigned long address, int *type);
struct file *shmem_file_setup(char * name, loff_t size, unsigned long flags);
void shmem_lock(struct file * file, int lock);
int shmem_zero_setup(struct vm_area_struct *);

/*
 * Parameter block passed down to zap_pte_range in exceptional cases.
 */
struct zap_details {
        struct vm_area_struct *nonlinear_vma;   /* Check page->index if set */
        struct address_space *check_mapping;    /* Check page->mapping if set */
        pgoff_t first_index;                    /* Lowest page->index to unmap */
        pgoff_t last_index;                     /* Highest page->index to unmap */
};

void zap_page_range(struct vm_area_struct *vma, unsigned long address,
                unsigned long size, struct zap_details *);
int unmap_vmas(struct mmu_gather **tlbp, struct mm_struct *mm,
                struct vm_area_struct *start_vma, unsigned long start_addr,
                unsigned long end_addr, unsigned long *nr_accounted,
                struct zap_details *);
void clear_page_tables(struct mmu_gather *tlb, unsigned long first, int nr);
int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
                        struct vm_area_struct *vma);
int zeromap_page_range(struct vm_area_struct *vma, unsigned long from,
                        unsigned long size, pgprot_t prot);
void unmap_mapping_range(struct address_space *mapping,
                loff_t const holebegin, loff_t const holelen, int even_cows);

static inline void unmap_shared_mapping_range(struct address_space *mapping,
                loff_t const holebegin, loff_t const holelen)
{
        unmap_mapping_range(mapping, holebegin, holelen, 0);
}

extern int vmtruncate(struct inode * inode, loff_t offset);
extern pmd_t *FASTCALL(__pmd_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address));
extern pte_t *FASTCALL(pte_alloc_kernel(struct mm_struct *mm, pmd_t *pmd, unsigned long address));
extern pte_t *FASTCALL(pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, unsigned long address));
extern int install_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, struct page *page, pgprot_t prot);
extern int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long pgoff, pgprot_t prot);
extern int handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma, unsigned long address, int write_access);
extern int make_pages_present(unsigned long addr, unsigned long end);
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
void put_dirty_page(struct task_struct *tsk, struct page *page,
                        unsigned long address, pgprot_t prot);

int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start,
                int len, int write, int force, struct page **pages, struct vm_area_struct **vmas);

int __set_page_dirty_buffers(struct page *page);
int __set_page_dirty_nobuffers(struct page *page);
int redirty_page_for_writepage(struct writeback_control *wbc,
                                struct page *page);
int FASTCALL(set_page_dirty(struct page *page));
int set_page_dirty_lock(struct page *page);
int clear_page_dirty_for_io(struct page *page);

/*
 * Prototype to add a shrinker callback for ageable caches.
 * 
 * These functions are passed a count `nr_to_scan' and a gfpmask.  They should
 * scan `nr_to_scan' objects, attempting to free them.
 *
 * The callback must the number of objects which remain in the cache.
 *
 * The callback will be passes nr_to_scan == 0 when the VM is querying the
 * cache size, so a fastpath for that case is appropriate.
 */
typedef int (*shrinker_t)(int nr_to_scan, unsigned int gfp_mask);

/*
 * Add an aging callback.  The int is the number of 'seeks' it takes
 * to recreate one of the objects that these functions age.
 */

#define DEFAULT_SEEKS 2
struct shrinker;
extern struct shrinker *set_shrinker(int, shrinker_t);
extern void remove_shrinker(struct shrinker *shrinker);

/*
 * On a two-level page table, this ends up being trivial. Thus the
 * inlining and the symmetry break with pte_alloc_map() that does all
 * of this out-of-line.
 */
static inline pmd_t *pmd_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
        if (pgd_none(*pgd))
                return __pmd_alloc(mm, pgd, address);
        return pmd_offset(pgd, address);
}

extern void free_area_init(unsigned long * zones_size);
extern void free_area_init_node(int nid, pg_data_t *pgdat, struct page *pmap,
        unsigned long * zones_size, unsigned long zone_start_pfn, 
        unsigned long *zholes_size);
extern void memmap_init_zone(struct page *, unsigned long, int,
        unsigned long, unsigned long);
extern void mem_init(void);
extern void show_mem(void);
extern void si_meminfo(struct sysinfo * val);
extern void si_meminfo_node(struct sysinfo *val, int nid);

/* mmap.c */
extern void insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
extern void __vma_link_rb(struct mm_struct *, struct vm_area_struct *,
        struct rb_node **, struct rb_node *);
extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
        unsigned long addr, unsigned long len, unsigned long pgoff);
extern void exit_mmap(struct mm_struct *);

extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);

extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
        unsigned long len, unsigned long prot,
        unsigned long flag, unsigned long pgoff);

static inline unsigned long do_mmap(struct file *file, unsigned long addr,
        unsigned long len, unsigned long prot,
        unsigned long flag, unsigned long offset)
{
        unsigned long ret = -EINVAL;
        if ((offset + PAGE_ALIGN(len)) < offset)
                goto out;
        if (!(offset & ~PAGE_MASK))
                ret = do_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
out:
        return ret;
}

extern int do_munmap(struct mm_struct *, unsigned long, size_t);

extern unsigned long do_brk(unsigned long, unsigned long);

static inline void
__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
                struct vm_area_struct *prev)
{
        prev->vm_next = vma->vm_next;
        rb_erase(&vma->vm_rb, &mm->mm_rb);
        if (mm->mmap_cache == vma)
                mm->mmap_cache = prev;
}

static inline int
can_vma_merge(struct vm_area_struct *vma, unsigned long vm_flags)
{
#ifdef CONFIG_MMU
        if (!vma->vm_file && vma->vm_flags == vm_flags)
                return 1;
#endif
        return 0;
}

/* filemap.c */
extern unsigned long page_unuse(struct page *);
extern void truncate_inode_pages(struct address_space *, loff_t);

/* generic vm_area_ops exported for stackable file systems */
struct page *filemap_nopage(struct vm_area_struct *, unsigned long, int *);

/* mm/page-writeback.c */
int write_one_page(struct page *page, int wait);

/* readahead.c */
#define VM_MAX_READAHEAD        128     /* kbytes */
#define VM_MIN_READAHEAD        16      /* kbytes (includes current page) */

int do_page_cache_readahead(struct address_space *mapping, struct file *filp,
                        unsigned long offset, unsigned long nr_to_read);
int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
                        unsigned long offset, unsigned long nr_to_read);
void page_cache_readahead(struct address_space *mapping, 
                          struct file_ra_state *ra,
                          struct file *filp,
                          unsigned long offset);
void handle_ra_miss(struct address_space *mapping, 
                    struct file_ra_state *ra, pgoff_t offset);
unsigned long max_sane_readahead(unsigned long nr);

/* Do stack extension */
extern int expand_stack(struct vm_area_struct * vma, unsigned long address);

/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr);
extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr,
                                             struct vm_area_struct **pprev);
extern int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
                     unsigned long addr, int new_below);

/* Look up the first VMA which intersects the interval start_addr..end_addr-1,
   NULL if none.  Assume start_addr < end_addr. */
static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * mm, unsigned long start_addr, unsigned long end_addr)
{
        struct vm_area_struct * vma = find_vma(mm,start_addr);

        if (vma && end_addr <= vma->vm_start)
                vma = NULL;
        return vma;
}

extern struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr);

extern unsigned int nr_used_zone_pages(void);

extern struct page * vmalloc_to_page(void *addr);
extern struct page * follow_page(struct mm_struct *mm, unsigned long address,
                int write);
extern int remap_page_range(struct vm_area_struct *vma, unsigned long from,
                unsigned long to, unsigned long size, pgprot_t prot);

#ifndef CONFIG_DEBUG_PAGEALLOC
static inline void
kernel_map_pages(struct page *page, int numpages, int enable)
{
}
#endif

#ifndef CONFIG_ARCH_GATE_AREA
extern struct vm_area_struct *get_gate_vma(struct task_struct *tsk);
int in_gate_area(struct task_struct *task, unsigned long addr);
#endif

#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */