mmap.c 64.3 KB
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/*
 * mm/mmap.c
 *
 * Written by obz.
 *
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 * Address space accounting code	<alan@lxorguk.ukuu.org.uk>
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 */

#include <linux/slab.h>
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#include <linux/backing-dev.h>
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#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/syscalls.h>
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#include <linux/capability.h>
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#include <linux/init.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/hugetlb.h>
#include <linux/profile.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/mempolicy.h>
#include <linux/rmap.h>
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#include <linux/mmu_notifier.h>
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#include <asm/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/tlb.h>
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#include <asm/mmu_context.h>
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#include "internal.h"

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#ifndef arch_mmap_check
#define arch_mmap_check(addr, len, flags)	(0)
#endif

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#ifndef arch_rebalance_pgtables
#define arch_rebalance_pgtables(addr, len)		(addr)
#endif

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static void unmap_region(struct mm_struct *mm,
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end);

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/*
 * WARNING: the debugging will use recursive algorithms so never enable this
 * unless you know what you are doing.
 */
#undef DEBUG_MM_RB

/* description of effects of mapping type and prot in current implementation.
 * this is due to the limited x86 page protection hardware.  The expected
 * behavior is in parens:
 *
 * map_type	prot
 *		PROT_NONE	PROT_READ	PROT_WRITE	PROT_EXEC
 * MAP_SHARED	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
 *		w: (no) no	w: (no) no	w: (yes) yes	w: (no) no
 *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
 *		
 * MAP_PRIVATE	r: (no) no	r: (yes) yes	r: (no) yes	r: (no) yes
 *		w: (no) no	w: (no) no	w: (copy) copy	w: (no) no
 *		x: (no) no	x: (no) yes	x: (no) yes	x: (yes) yes
 *
 */
pgprot_t protection_map[16] = {
	__P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
	__S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
};

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pgprot_t vm_get_page_prot(unsigned long vm_flags)
{
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	return __pgprot(pgprot_val(protection_map[vm_flags &
				(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
			pgprot_val(arch_vm_get_page_prot(vm_flags)));
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}
EXPORT_SYMBOL(vm_get_page_prot);

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int sysctl_overcommit_memory = OVERCOMMIT_GUESS;  /* heuristic overcommit */
int sysctl_overcommit_ratio = 50;	/* default is 50% */
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int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
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atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);
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/*
 * Check that a process has enough memory to allocate a new virtual
 * mapping. 0 means there is enough memory for the allocation to
 * succeed and -ENOMEM implies there is not.
 *
 * We currently support three overcommit policies, which are set via the
 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
 *
 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
 * Additional code 2002 Jul 20 by Robert Love.
 *
 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 *
 * Note this is a helper function intended to be used by LSMs which
 * wish to use this logic.
 */
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int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
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{
	unsigned long free, allowed;

	vm_acct_memory(pages);

	/*
	 * Sometimes we want to use more memory than we have
	 */
	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
		return 0;

	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
		unsigned long n;

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		free = global_page_state(NR_FILE_PAGES);
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		free += nr_swap_pages;

		/*
		 * Any slabs which are created with the
		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
		 * which are reclaimable, under pressure.  The dentry
		 * cache and most inode caches should fall into this
		 */
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		free += global_page_state(NR_SLAB_RECLAIMABLE);
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		/*
		 * Leave the last 3% for root
		 */
		if (!cap_sys_admin)
			free -= free / 32;

		if (free > pages)
			return 0;

		/*
		 * nr_free_pages() is very expensive on large systems,
		 * only call if we're about to fail.
		 */
		n = nr_free_pages();
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		/*
		 * Leave reserved pages. The pages are not for anonymous pages.
		 */
		if (n <= totalreserve_pages)
			goto error;
		else
			n -= totalreserve_pages;

		/*
		 * Leave the last 3% for root
		 */
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		if (!cap_sys_admin)
			n -= n / 32;
		free += n;

		if (free > pages)
			return 0;
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		goto error;
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	}

	allowed = (totalram_pages - hugetlb_total_pages())
	       	* sysctl_overcommit_ratio / 100;
	/*
	 * Leave the last 3% for root
	 */
	if (!cap_sys_admin)
		allowed -= allowed / 32;
	allowed += total_swap_pages;

	/* Don't let a single process grow too big:
	   leave 3% of the size of this process for other processes */
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	if (mm)
		allowed -= mm->total_vm / 32;
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	/*
	 * cast `allowed' as a signed long because vm_committed_space
	 * sometimes has a negative value
	 */
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	if (atomic_long_read(&vm_committed_space) < (long)allowed)
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		return 0;
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error:
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	vm_unacct_memory(pages);

	return -ENOMEM;
}

/*
 * Requires inode->i_mapping->i_mmap_lock
 */
static void __remove_shared_vm_struct(struct vm_area_struct *vma,
		struct file *file, struct address_space *mapping)
{
	if (vma->vm_flags & VM_DENYWRITE)
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		atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
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	if (vma->vm_flags & VM_SHARED)
		mapping->i_mmap_writable--;

	flush_dcache_mmap_lock(mapping);
	if (unlikely(vma->vm_flags & VM_NONLINEAR))
		list_del_init(&vma->shared.vm_set.list);
	else
		vma_prio_tree_remove(vma, &mapping->i_mmap);
	flush_dcache_mmap_unlock(mapping);
}

/*
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 * Unlink a file-based vm structure from its prio_tree, to hide
 * vma from rmap and vmtruncate before freeing its page tables.
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 */
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void unlink_file_vma(struct vm_area_struct *vma)
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{
	struct file *file = vma->vm_file;

	if (file) {
		struct address_space *mapping = file->f_mapping;
		spin_lock(&mapping->i_mmap_lock);
		__remove_shared_vm_struct(vma, file, mapping);
		spin_unlock(&mapping->i_mmap_lock);
	}
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}

/*
 * Close a vm structure and free it, returning the next.
 */
static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
{
	struct vm_area_struct *next = vma->vm_next;

	might_sleep();
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	if (vma->vm_ops && vma->vm_ops->close)
		vma->vm_ops->close(vma);
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	if (vma->vm_file) {
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		fput(vma->vm_file);
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		if (vma->vm_flags & VM_EXECUTABLE)
			removed_exe_file_vma(vma->vm_mm);
	}
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	mpol_put(vma_policy(vma));
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	kmem_cache_free(vm_area_cachep, vma);
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	return next;
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}

asmlinkage unsigned long sys_brk(unsigned long brk)
{
	unsigned long rlim, retval;
	unsigned long newbrk, oldbrk;
	struct mm_struct *mm = current->mm;
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	unsigned long min_brk;
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	down_write(&mm->mmap_sem);

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#ifdef CONFIG_COMPAT_BRK
	min_brk = mm->end_code;
#else
	min_brk = mm->start_brk;
#endif
	if (brk < min_brk)
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		goto out;
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	/*
	 * Check against rlimit here. If this check is done later after the test
	 * of oldbrk with newbrk then it can escape the test and let the data
	 * segment grow beyond its set limit the in case where the limit is
	 * not page aligned -Ram Gupta
	 */
	rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
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	if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
			(mm->end_data - mm->start_data) > rlim)
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		goto out;

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	newbrk = PAGE_ALIGN(brk);
	oldbrk = PAGE_ALIGN(mm->brk);
	if (oldbrk == newbrk)
		goto set_brk;

	/* Always allow shrinking brk. */
	if (brk <= mm->brk) {
		if (!do_munmap(mm, newbrk, oldbrk-newbrk))
			goto set_brk;
		goto out;
	}

	/* Check against existing mmap mappings. */
	if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
		goto out;

	/* Ok, looks good - let it rip. */
	if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
		goto out;
set_brk:
	mm->brk = brk;
out:
	retval = mm->brk;
	up_write(&mm->mmap_sem);
	return retval;
}

#ifdef DEBUG_MM_RB
static int browse_rb(struct rb_root *root)
{
	int i = 0, j;
	struct rb_node *nd, *pn = NULL;
	unsigned long prev = 0, pend = 0;

	for (nd = rb_first(root); nd; nd = rb_next(nd)) {
		struct vm_area_struct *vma;
		vma = rb_entry(nd, struct vm_area_struct, vm_rb);
		if (vma->vm_start < prev)
			printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
		if (vma->vm_start < pend)
			printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
		if (vma->vm_start > vma->vm_end)
			printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
		i++;
		pn = nd;
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		prev = vma->vm_start;
		pend = vma->vm_end;
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	}
	j = 0;
	for (nd = pn; nd; nd = rb_prev(nd)) {
		j++;
	}
	if (i != j)
		printk("backwards %d, forwards %d\n", j, i), i = 0;
	return i;
}

void validate_mm(struct mm_struct *mm)
{
	int bug = 0;
	int i = 0;
	struct vm_area_struct *tmp = mm->mmap;
	while (tmp) {
		tmp = tmp->vm_next;
		i++;
	}
	if (i != mm->map_count)
		printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
	i = browse_rb(&mm->mm_rb);
	if (i != mm->map_count)
		printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
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	BUG_ON(bug);
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}
#else
#define validate_mm(mm) do { } while (0)
#endif

static struct vm_area_struct *
find_vma_prepare(struct mm_struct *mm, unsigned long addr,
		struct vm_area_struct **pprev, struct rb_node ***rb_link,
		struct rb_node ** rb_parent)
{
	struct vm_area_struct * vma;
	struct rb_node ** __rb_link, * __rb_parent, * rb_prev;

	__rb_link = &mm->mm_rb.rb_node;
	rb_prev = __rb_parent = NULL;
	vma = NULL;

	while (*__rb_link) {
		struct vm_area_struct *vma_tmp;

		__rb_parent = *__rb_link;
		vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);

		if (vma_tmp->vm_end > addr) {
			vma = vma_tmp;
			if (vma_tmp->vm_start <= addr)
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				break;
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			__rb_link = &__rb_parent->rb_left;
		} else {
			rb_prev = __rb_parent;
			__rb_link = &__rb_parent->rb_right;
		}
	}

	*pprev = NULL;
	if (rb_prev)
		*pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
	*rb_link = __rb_link;
	*rb_parent = __rb_parent;
	return vma;
}

static inline void
__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
		struct vm_area_struct *prev, struct rb_node *rb_parent)
{
	if (prev) {
		vma->vm_next = prev->vm_next;
		prev->vm_next = vma;
	} else {
		mm->mmap = vma;
		if (rb_parent)
			vma->vm_next = rb_entry(rb_parent,
					struct vm_area_struct, vm_rb);
		else
			vma->vm_next = NULL;
	}
}

void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
		struct rb_node **rb_link, struct rb_node *rb_parent)
{
	rb_link_node(&vma->vm_rb, rb_parent, rb_link);
	rb_insert_color(&vma->vm_rb, &mm->mm_rb);
}

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static void __vma_link_file(struct vm_area_struct *vma)
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{
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	struct file *file;
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	file = vma->vm_file;
	if (file) {
		struct address_space *mapping = file->f_mapping;

		if (vma->vm_flags & VM_DENYWRITE)
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			atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
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		if (vma->vm_flags & VM_SHARED)
			mapping->i_mmap_writable++;

		flush_dcache_mmap_lock(mapping);
		if (unlikely(vma->vm_flags & VM_NONLINEAR))
			vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
		else
			vma_prio_tree_insert(vma, &mapping->i_mmap);
		flush_dcache_mmap_unlock(mapping);
	}
}

static void
__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
	struct vm_area_struct *prev, struct rb_node **rb_link,
	struct rb_node *rb_parent)
{
	__vma_link_list(mm, vma, prev, rb_parent);
	__vma_link_rb(mm, vma, rb_link, rb_parent);
	__anon_vma_link(vma);
}

static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
			struct vm_area_struct *prev, struct rb_node **rb_link,
			struct rb_node *rb_parent)
{
	struct address_space *mapping = NULL;

	if (vma->vm_file)
		mapping = vma->vm_file->f_mapping;

	if (mapping) {
		spin_lock(&mapping->i_mmap_lock);
		vma->vm_truncate_count = mapping->truncate_count;
	}
	anon_vma_lock(vma);

	__vma_link(mm, vma, prev, rb_link, rb_parent);
	__vma_link_file(vma);

	anon_vma_unlock(vma);
	if (mapping)
		spin_unlock(&mapping->i_mmap_lock);

	mm->map_count++;
	validate_mm(mm);
}

/*
 * Helper for vma_adjust in the split_vma insert case:
 * insert vm structure into list and rbtree and anon_vma,
 * but it has already been inserted into prio_tree earlier.
 */
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static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
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{
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	struct vm_area_struct *__vma, *prev;
	struct rb_node **rb_link, *rb_parent;
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	__vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
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	BUG_ON(__vma && __vma->vm_start < vma->vm_end);
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	__vma_link(mm, vma, prev, rb_link, rb_parent);
	mm->map_count++;
}

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;
}

/*
 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 * is already present in an i_mmap tree without adjusting the tree.
 * The following helper function should be used when such adjustments
 * are necessary.  The "insert" vma (if any) is to be inserted
 * before we drop the necessary locks.
 */
void vma_adjust(struct vm_area_struct *vma, unsigned long start,
	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
{
	struct mm_struct *mm = vma->vm_mm;
	struct vm_area_struct *next = vma->vm_next;
	struct vm_area_struct *importer = NULL;
	struct address_space *mapping = NULL;
	struct prio_tree_root *root = NULL;
	struct file *file = vma->vm_file;
	struct anon_vma *anon_vma = NULL;
	long adjust_next = 0;
	int remove_next = 0;

	if (next && !insert) {
		if (end >= next->vm_end) {
			/*
			 * vma expands, overlapping all the next, and
			 * perhaps the one after too (mprotect case 6).
			 */
again:			remove_next = 1 + (end > next->vm_end);
			end = next->vm_end;
			anon_vma = next->anon_vma;
			importer = vma;
		} else if (end > next->vm_start) {
			/*
			 * vma expands, overlapping part of the next:
			 * mprotect case 5 shifting the boundary up.
			 */
			adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
			anon_vma = next->anon_vma;
			importer = vma;
		} else if (end < vma->vm_end) {
			/*
			 * vma shrinks, and !insert tells it's not
			 * split_vma inserting another: so it must be
			 * mprotect case 4 shifting the boundary down.
			 */
			adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
			anon_vma = next->anon_vma;
			importer = next;
		}
	}

	if (file) {
		mapping = file->f_mapping;
		if (!(vma->vm_flags & VM_NONLINEAR))
			root = &mapping->i_mmap;
		spin_lock(&mapping->i_mmap_lock);
		if (importer &&
		    vma->vm_truncate_count != next->vm_truncate_count) {
			/*
			 * unmap_mapping_range might be in progress:
			 * ensure that the expanding vma is rescanned.
			 */
			importer->vm_truncate_count = 0;
		}
		if (insert) {
			insert->vm_truncate_count = vma->vm_truncate_count;
			/*
			 * Put into prio_tree now, so instantiated pages
			 * are visible to arm/parisc __flush_dcache_page
			 * throughout; but we cannot insert into address
			 * space until vma start or end is updated.
			 */
			__vma_link_file(insert);
		}
	}

	/*
	 * When changing only vma->vm_end, we don't really need
	 * anon_vma lock: but is that case worth optimizing out?
	 */
	if (vma->anon_vma)
		anon_vma = vma->anon_vma;
	if (anon_vma) {
		spin_lock(&anon_vma->lock);
		/*
		 * Easily overlooked: when mprotect shifts the boundary,
		 * make sure the expanding vma has anon_vma set if the
		 * shrinking vma had, to cover any anon pages imported.
		 */
		if (importer && !importer->anon_vma) {
			importer->anon_vma = anon_vma;
			__anon_vma_link(importer);
		}
	}

	if (root) {
		flush_dcache_mmap_lock(mapping);
		vma_prio_tree_remove(vma, root);
		if (adjust_next)
			vma_prio_tree_remove(next, root);
	}

	vma->vm_start = start;
	vma->vm_end = end;
	vma->vm_pgoff = pgoff;
	if (adjust_next) {
		next->vm_start += adjust_next << PAGE_SHIFT;
		next->vm_pgoff += adjust_next;
	}

	if (root) {
		if (adjust_next)
			vma_prio_tree_insert(next, root);
		vma_prio_tree_insert(vma, root);
		flush_dcache_mmap_unlock(mapping);
	}

	if (remove_next) {
		/*
		 * vma_merge has merged next into vma, and needs
		 * us to remove next before dropping the locks.
		 */
		__vma_unlink(mm, next, vma);
		if (file)
			__remove_shared_vm_struct(next, file, mapping);
		if (next->anon_vma)
			__anon_vma_merge(vma, next);
	} else if (insert) {
		/*
		 * split_vma has split insert from vma, and needs
		 * us to insert it before dropping the locks
		 * (it may either follow vma or precede it).
		 */
		__insert_vm_struct(mm, insert);
	}

	if (anon_vma)
		spin_unlock(&anon_vma->lock);
	if (mapping)
		spin_unlock(&mapping->i_mmap_lock);

	if (remove_next) {
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		if (file) {
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			fput(file);
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			if (next->vm_flags & VM_EXECUTABLE)
				removed_exe_file_vma(mm);
		}
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		mm->map_count--;
645
		mpol_put(vma_policy(next));
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		kmem_cache_free(vm_area_cachep, next);
		/*
		 * In mprotect's case 6 (see comments on vma_merge),
		 * we must remove another next too. It would clutter
		 * up the code too much to do both in one go.
		 */
		if (remove_next == 2) {
			next = vma->vm_next;
			goto again;
		}
	}

	validate_mm(mm);
}

/*
 * If the vma has a ->close operation then the driver probably needs to release
 * per-vma resources, so we don't attempt to merge those.
 */
static inline int is_mergeable_vma(struct vm_area_struct *vma,
			struct file *file, unsigned long vm_flags)
{
	if (vma->vm_flags != vm_flags)
		return 0;
	if (vma->vm_file != file)
		return 0;
	if (vma->vm_ops && vma->vm_ops->close)
		return 0;
	return 1;
}

static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
					struct anon_vma *anon_vma2)
{
	return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
}

/*
 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 * in front of (at a lower virtual address and file offset than) the vma.
 *
 * We cannot merge two vmas if they have differently assigned (non-NULL)
 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 *
 * We don't check here for the merged mmap wrapping around the end of pagecache
 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
 * wrap, nor mmaps which cover the final page at index -1UL.
 */
static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
{
	if (is_mergeable_vma(vma, file, vm_flags) &&
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
		if (vma->vm_pgoff == vm_pgoff)
			return 1;
	}
	return 0;
}

/*
 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 * beyond (at a higher virtual address and file offset than) the vma.
 *
 * We cannot merge two vmas if they have differently assigned (non-NULL)
 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 */
static int
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
{
	if (is_mergeable_vma(vma, file, vm_flags) &&
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
		pgoff_t vm_pglen;
		vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
		if (vma->vm_pgoff + vm_pglen == vm_pgoff)
			return 1;
	}
	return 0;
}

/*
 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
 * whether that can be merged with its predecessor or its successor.
 * Or both (it neatly fills a hole).
 *
 * In most cases - when called for mmap, brk or mremap - [addr,end) is
 * certain not to be mapped by the time vma_merge is called; but when
 * called for mprotect, it is certain to be already mapped (either at
 * an offset within prev, or at the start of next), and the flags of
 * this area are about to be changed to vm_flags - and the no-change
 * case has already been eliminated.
 *
 * The following mprotect cases have to be considered, where AAAA is
 * the area passed down from mprotect_fixup, never extending beyond one
 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
 *
 *     AAAA             AAAA                AAAA          AAAA
 *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
 *    cannot merge    might become    might become    might become
 *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
 *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
 *    mremap move:                                    PPPPNNNNNNNN 8
 *        AAAA
 *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
 *    might become    case 1 below    case 2 below    case 3 below
 *
 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
 */
struct vm_area_struct *vma_merge(struct mm_struct *mm,
			struct vm_area_struct *prev, unsigned long addr,
			unsigned long end, unsigned long vm_flags,
		     	struct anon_vma *anon_vma, struct file *file,
			pgoff_t pgoff, struct mempolicy *policy)
{
	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
	struct vm_area_struct *area, *next;

	/*
	 * We later require that vma->vm_flags == vm_flags,
	 * so this tests vma->vm_flags & VM_SPECIAL, too.
	 */
	if (vm_flags & VM_SPECIAL)
		return NULL;

	if (prev)
		next = prev->vm_next;
	else
		next = mm->mmap;
	area = next;
	if (next && next->vm_end == end)		/* cases 6, 7, 8 */
		next = next->vm_next;

	/*
	 * Can it merge with the predecessor?
	 */
	if (prev && prev->vm_end == addr &&
  			mpol_equal(vma_policy(prev), policy) &&
			can_vma_merge_after(prev, vm_flags,
						anon_vma, file, pgoff)) {
		/*
		 * OK, it can.  Can we now merge in the successor as well?
		 */
		if (next && end == next->vm_start &&
				mpol_equal(policy, vma_policy(next)) &&
				can_vma_merge_before(next, vm_flags,
					anon_vma, file, pgoff+pglen) &&
				is_mergeable_anon_vma(prev->anon_vma,
						      next->anon_vma)) {
							/* cases 1, 6 */
			vma_adjust(prev, prev->vm_start,
				next->vm_end, prev->vm_pgoff, NULL);
		} else					/* cases 2, 5, 7 */
			vma_adjust(prev, prev->vm_start,
				end, prev->vm_pgoff, NULL);
		return prev;
	}

	/*
	 * Can this new request be merged in front of next?
	 */
	if (next && end == next->vm_start &&
 			mpol_equal(policy, vma_policy(next)) &&
			can_vma_merge_before(next, vm_flags,
					anon_vma, file, pgoff+pglen)) {
		if (prev && addr < prev->vm_end)	/* case 4 */
			vma_adjust(prev, prev->vm_start,
				addr, prev->vm_pgoff, NULL);
		else					/* cases 3, 8 */
			vma_adjust(area, addr, next->vm_end,
				next->vm_pgoff - pglen, NULL);
		return area;
	}

	return NULL;
}

/*
 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
 * neighbouring vmas for a suitable anon_vma, before it goes off
 * to allocate a new anon_vma.  It checks because a repetitive
 * sequence of mprotects and faults may otherwise lead to distinct
 * anon_vmas being allocated, preventing vma merge in subsequent
 * mprotect.
 */
struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
{
	struct vm_area_struct *near;
	unsigned long vm_flags;

	near = vma->vm_next;
	if (!near)
		goto try_prev;

	/*
	 * Since only mprotect tries to remerge vmas, match flags
	 * which might be mprotected into each other later on.
	 * Neither mlock nor madvise tries to remerge at present,
	 * so leave their flags as obstructing a merge.
	 */
	vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
	vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);

	if (near->anon_vma && vma->vm_end == near->vm_start &&
 			mpol_equal(vma_policy(vma), vma_policy(near)) &&
			can_vma_merge_before(near, vm_flags,
				NULL, vma->vm_file, vma->vm_pgoff +
				((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
		return near->anon_vma;
try_prev:
	/*
	 * It is potentially slow to have to call find_vma_prev here.
	 * But it's only on the first write fault on the vma, not
	 * every time, and we could devise a way to avoid it later
	 * (e.g. stash info in next's anon_vma_node when assigning
	 * an anon_vma, or when trying vma_merge).  Another time.
	 */
864
	BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
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865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888
	if (!near)
		goto none;

	vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
	vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);

	if (near->anon_vma && near->vm_end == vma->vm_start &&
  			mpol_equal(vma_policy(near), vma_policy(vma)) &&
			can_vma_merge_after(near, vm_flags,
				NULL, vma->vm_file, vma->vm_pgoff))
		return near->anon_vma;
none:
	/*
	 * There's no absolute need to look only at touching neighbours:
	 * we could search further afield for "compatible" anon_vmas.
	 * But it would probably just be a waste of time searching,
	 * or lead to too many vmas hanging off the same anon_vma.
	 * We're trying to allow mprotect remerging later on,
	 * not trying to minimize memory used for anon_vmas.
	 */
	return NULL;
}

#ifdef CONFIG_PROC_FS
889
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
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890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909
						struct file *file, long pages)
{
	const unsigned long stack_flags
		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);

	if (file) {
		mm->shared_vm += pages;
		if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
			mm->exec_vm += pages;
	} else if (flags & stack_flags)
		mm->stack_vm += pages;
	if (flags & (VM_RESERVED|VM_IO))
		mm->reserved_vm += pages;
}
#endif /* CONFIG_PROC_FS */

/*
 * The caller must hold down_write(current->mm->mmap_sem).
 */

Z
ZhenwenXu 已提交
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unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
L
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			unsigned long len, unsigned long prot,
			unsigned long flags, unsigned long pgoff)
{
	struct mm_struct * mm = current->mm;
	struct inode *inode;
	unsigned int vm_flags;
	int error;
	int accountable = 1;
M
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	unsigned long reqprot = prot;
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920 921 922 923 924 925 926 927

	/*
	 * Does the application expect PROT_READ to imply PROT_EXEC?
	 *
	 * (the exception is when the underlying filesystem is noexec
	 *  mounted, in which case we dont add PROT_EXEC.)
	 */
	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
928
		if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
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			prot |= PROT_EXEC;

	if (!len)
		return -EINVAL;

934 935 936
	if (!(flags & MAP_FIXED))
		addr = round_hint_to_min(addr);

937 938 939 940
	error = arch_mmap_check(addr, len, flags);
	if (error)
		return error;

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941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972
	/* Careful about overflows.. */
	len = PAGE_ALIGN(len);
	if (!len || len > TASK_SIZE)
		return -ENOMEM;

	/* offset overflow? */
	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
               return -EOVERFLOW;

	/* Too many mappings? */
	if (mm->map_count > sysctl_max_map_count)
		return -ENOMEM;

	/* Obtain the address to map to. we verify (or select) it and ensure
	 * that it represents a valid section of the address space.
	 */
	addr = get_unmapped_area(file, addr, len, pgoff, flags);
	if (addr & ~PAGE_MASK)
		return addr;

	/* Do simple checking here so the lower-level routines won't have
	 * to. we assume access permissions have been handled by the open
	 * of the memory object, so we don't do any here.
	 */
	vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
			mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;

	if (flags & MAP_LOCKED) {
		if (!can_do_mlock())
			return -EPERM;
		vm_flags |= VM_LOCKED;
	}
973

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974 975 976
	/* mlock MCL_FUTURE? */
	if (vm_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
977 978
		locked = len >> PAGE_SHIFT;
		locked += mm->locked_vm;
L
Linus Torvalds 已提交
979
		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
980
		lock_limit >>= PAGE_SHIFT;
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981 982 983 984
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			return -EAGAIN;
	}

985
	inode = file ? file->f_path.dentry->d_inode : NULL;
L
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986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013

	if (file) {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
			if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
				return -EACCES;

			/*
			 * Make sure we don't allow writing to an append-only
			 * file..
			 */
			if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
				return -EACCES;

			/*
			 * Make sure there are no mandatory locks on the file.
			 */
			if (locks_verify_locked(inode))
				return -EAGAIN;

			vm_flags |= VM_SHARED | VM_MAYSHARE;
			if (!(file->f_mode & FMODE_WRITE))
				vm_flags &= ~(VM_MAYWRITE | VM_SHARED);

			/* fall through */
		case MAP_PRIVATE:
			if (!(file->f_mode & FMODE_READ))
				return -EACCES;
1014
			if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
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				if (vm_flags & VM_EXEC)
					return -EPERM;
				vm_flags &= ~VM_MAYEXEC;
			}
			if (is_file_hugepages(file))
				accountable = 0;

			if (!file->f_op || !file->f_op->mmap)
				return -ENODEV;
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			break;

		default:
			return -EINVAL;
		}
	} else {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
1032 1033 1034 1035
			/*
			 * Ignore pgoff.
			 */
			pgoff = 0;
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1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048
			vm_flags |= VM_SHARED | VM_MAYSHARE;
			break;
		case MAP_PRIVATE:
			/*
			 * Set pgoff according to addr for anon_vma.
			 */
			pgoff = addr >> PAGE_SHIFT;
			break;
		default:
			return -EINVAL;
		}
	}

1049
	error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
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1050 1051
	if (error)
		return error;
1052

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	return mmap_region(file, addr, len, flags, vm_flags, pgoff,
			   accountable);
}
EXPORT_SYMBOL(do_mmap_pgoff);

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Alexey Dobriyan 已提交
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/*
 * Some shared mappigns will want the pages marked read-only
 * to track write events. If so, we'll downgrade vm_page_prot
 * to the private version (using protection_map[] without the
 * VM_SHARED bit).
 */
int vma_wants_writenotify(struct vm_area_struct *vma)
{
	unsigned int vm_flags = vma->vm_flags;

	/* If it was private or non-writable, the write bit is already clear */
	if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
		return 0;

	/* The backer wishes to know when pages are first written to? */
	if (vma->vm_ops && vma->vm_ops->page_mkwrite)
		return 1;

	/* The open routine did something to the protections already? */
	if (pgprot_val(vma->vm_page_prot) !=
1078
	    pgprot_val(vm_get_page_prot(vm_flags)))
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1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089
		return 0;

	/* Specialty mapping? */
	if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
		return 0;

	/* Can the mapping track the dirty pages? */
	return vma->vm_file && vma->vm_file->f_mapping &&
		mapping_cap_account_dirty(vma->vm_file->f_mapping);
}

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unsigned long mmap_region(struct file *file, unsigned long addr,
			  unsigned long len, unsigned long flags,
			  unsigned int vm_flags, unsigned long pgoff,
			  int accountable)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma, *prev;
	int correct_wcount = 0;
	int error;
	struct rb_node **rb_link, *rb_parent;
	unsigned long charged = 0;
	struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;

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1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113
	/* Clear old maps */
	error = -ENOMEM;
munmap_back:
	vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
	if (vma && vma->vm_start < addr + len) {
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

	/* Check against address space limit. */
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	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
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		return -ENOMEM;

1117 1118 1119
	if (flags & MAP_NORESERVE)
		vm_flags |= VM_NORESERVE;

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1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140
	if (accountable && (!(flags & MAP_NORESERVE) ||
			    sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
		if (vm_flags & VM_SHARED) {
			/* Check memory availability in shmem_file_setup? */
			vm_flags |= VM_ACCOUNT;
		} else if (vm_flags & VM_WRITE) {
			/*
			 * Private writable mapping: check memory availability
			 */
			charged = len >> PAGE_SHIFT;
			if (security_vm_enough_memory(charged))
				return -ENOMEM;
			vm_flags |= VM_ACCOUNT;
		}
	}

	/*
	 * Can we just expand an old private anonymous mapping?
	 * The VM_SHARED test is necessary because shmem_zero_setup
	 * will create the file object for a shared anonymous map below.
	 */
1141 1142 1143 1144 1145 1146
	if (!file && !(vm_flags & VM_SHARED)) {
		vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
					NULL, NULL, pgoff, NULL);
		if (vma)
			goto out;
	}
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1147 1148 1149 1150 1151 1152

	/*
	 * Determine the object being mapped and call the appropriate
	 * specific mapper. the address has already been validated, but
	 * not unmapped, but the maps are removed from the list.
	 */
P
Pekka Enberg 已提交
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	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
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	if (!vma) {
		error = -ENOMEM;
		goto unacct_error;
	}

	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;
	vma->vm_flags = vm_flags;
1163
	vma->vm_page_prot = vm_get_page_prot(vm_flags);
L
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	vma->vm_pgoff = pgoff;

	if (file) {
		error = -EINVAL;
		if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
			goto free_vma;
		if (vm_flags & VM_DENYWRITE) {
			error = deny_write_access(file);
			if (error)
				goto free_vma;
			correct_wcount = 1;
		}
		vma->vm_file = file;
		get_file(file);
		error = file->f_op->mmap(file, vma);
		if (error)
			goto unmap_and_free_vma;
M
Matt Helsley 已提交
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		if (vm_flags & VM_EXECUTABLE)
			added_exe_file_vma(mm);
L
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	} else if (vm_flags & VM_SHARED) {
		error = shmem_zero_setup(vma);
		if (error)
			goto free_vma;
	}

	/* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
	 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
	 * that memory reservation must be checked; but that reservation
	 * belongs to shared memory object, not to vma: so now clear it.
	 */
	if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
		vma->vm_flags &= ~VM_ACCOUNT;

	/* Can addr have changed??
	 *
	 * Answer: Yes, several device drivers can do it in their
	 *         f_op->mmap method. -DaveM
	 */
	addr = vma->vm_start;
	pgoff = vma->vm_pgoff;
	vm_flags = vma->vm_flags;

1206
	if (vma_wants_writenotify(vma))
1207
		vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1208

1209
	if (file && vma_merge(mm, prev, addr, vma->vm_end,
L
Linus Torvalds 已提交
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			vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1211
		mpol_put(vma_policy(vma));
L
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1212
		kmem_cache_free(vm_area_cachep, vma);
1213
		fput(file);
M
Matt Helsley 已提交
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		if (vm_flags & VM_EXECUTABLE)
			removed_exe_file_vma(mm);
1216 1217 1218
	} else {
		vma_link(mm, vma, prev, rb_link, rb_parent);
		file = vma->vm_file;
L
Linus Torvalds 已提交
1219
	}
1220 1221 1222 1223 1224

	/* Once vma denies write, undo our temporary denial count */
	if (correct_wcount)
		atomic_inc(&inode->i_writecount);
out:
L
Linus Torvalds 已提交
1225
	mm->total_vm += len >> PAGE_SHIFT;
1226
	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
L
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1227
	if (vm_flags & VM_LOCKED) {
1228 1229 1230 1231 1232 1233 1234 1235
		/*
		 * makes pages present; downgrades, drops, reacquires mmap_sem
		 */
		long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
		if (nr_pages < 0)
			return nr_pages;	/* vma gone! */
		mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
	} else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1236
		make_pages_present(addr, addr + len);
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	return addr;

unmap_and_free_vma:
	if (correct_wcount)
		atomic_inc(&inode->i_writecount);
	vma->vm_file = NULL;
	fput(file);

	/* Undo any partial mapping done by a device driver. */
1246 1247
	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
	charged = 0;
L
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free_vma:
	kmem_cache_free(vm_area_cachep, vma);
unacct_error:
	if (charged)
		vm_unacct_memory(charged);
	return error;
}

/* Get an address range which is currently unmapped.
 * For shmat() with addr=0.
 *
 * Ugly calling convention alert:
 * Return value with the low bits set means error value,
 * ie
 *	if (ret & ~PAGE_MASK)
 *		error = ret;
 *
 * This function "knows" that -ENOMEM has the bits set.
 */
#ifndef HAVE_ARCH_UNMAPPED_AREA
unsigned long
arch_get_unmapped_area(struct file *filp, unsigned long addr,
		unsigned long len, unsigned long pgoff, unsigned long flags)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long start_addr;

	if (len > TASK_SIZE)
		return -ENOMEM;

1279 1280 1281
	if (flags & MAP_FIXED)
		return addr;

L
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	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}
1289 1290 1291 1292 1293 1294
	if (len > mm->cached_hole_size) {
	        start_addr = addr = mm->free_area_cache;
	} else {
	        start_addr = addr = TASK_UNMAPPED_BASE;
	        mm->cached_hole_size = 0;
	}
L
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full_search:
	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
		/* At this point:  (!vma || addr < vma->vm_end). */
		if (TASK_SIZE - len < addr) {
			/*
			 * Start a new search - just in case we missed
			 * some holes.
			 */
			if (start_addr != TASK_UNMAPPED_BASE) {
1305 1306 1307
				addr = TASK_UNMAPPED_BASE;
			        start_addr = addr;
				mm->cached_hole_size = 0;
L
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				goto full_search;
			}
			return -ENOMEM;
		}
		if (!vma || addr + len <= vma->vm_start) {
			/*
			 * Remember the place where we stopped the search:
			 */
			mm->free_area_cache = addr + len;
			return addr;
		}
1319 1320
		if (addr + mm->cached_hole_size < vma->vm_start)
		        mm->cached_hole_size = vma->vm_start - addr;
L
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		addr = vma->vm_end;
	}
}
#endif	

1326
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
L
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{
	/*
	 * Is this a new hole at the lowest possible address?
	 */
1331 1332 1333 1334
	if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
		mm->free_area_cache = addr;
		mm->cached_hole_size = ~0UL;
	}
L
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}

/*
 * This mmap-allocator allocates new areas top-down from below the
 * stack's low limit (the base):
 */
#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
unsigned long
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
			  const unsigned long len, const unsigned long pgoff,
			  const unsigned long flags)
{
	struct vm_area_struct *vma;
	struct mm_struct *mm = current->mm;
	unsigned long addr = addr0;

	/* requested length too big for entire address space */
	if (len > TASK_SIZE)
		return -ENOMEM;

1355 1356 1357
	if (flags & MAP_FIXED)
		return addr;

L
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	/* requesting a specific address */
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
				(!vma || addr + len <= vma->vm_start))
			return addr;
	}

1367 1368 1369 1370 1371 1372
	/* check if free_area_cache is useful for us */
	if (len <= mm->cached_hole_size) {
 	        mm->cached_hole_size = 0;
 		mm->free_area_cache = mm->mmap_base;
 	}

L
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	/* either no address requested or can't fit in requested address hole */
	addr = mm->free_area_cache;

	/* make sure it can fit in the remaining address space */
1377
	if (addr > len) {
L
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		vma = find_vma(mm, addr-len);
		if (!vma || addr <= vma->vm_start)
			/* remember the address as a hint for next time */
			return (mm->free_area_cache = addr-len);
	}

1384 1385 1386
	if (mm->mmap_base < len)
		goto bottomup;

L
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	addr = mm->mmap_base-len;

	do {
		/*
		 * Lookup failure means no vma is above this address,
		 * else if new region fits below vma->vm_start,
		 * return with success:
		 */
		vma = find_vma(mm, addr);
		if (!vma || addr+len <= vma->vm_start)
			/* remember the address as a hint for next time */
			return (mm->free_area_cache = addr);

1400 1401 1402 1403
 		/* remember the largest hole we saw so far */
 		if (addr + mm->cached_hole_size < vma->vm_start)
 		        mm->cached_hole_size = vma->vm_start - addr;

L
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		/* try just below the current vma->vm_start */
		addr = vma->vm_start-len;
1406
	} while (len < vma->vm_start);
L
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1408
bottomup:
L
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	/*
	 * A failed mmap() very likely causes application failure,
	 * so fall back to the bottom-up function here. This scenario
	 * can happen with large stack limits and large mmap()
	 * allocations.
	 */
1415 1416
	mm->cached_hole_size = ~0UL;
  	mm->free_area_cache = TASK_UNMAPPED_BASE;
L
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	addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
	/*
	 * Restore the topdown base:
	 */
	mm->free_area_cache = mm->mmap_base;
1422
	mm->cached_hole_size = ~0UL;
L
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	return addr;
}
#endif

1428
void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
L
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{
	/*
	 * Is this a new hole at the highest possible address?
	 */
1433 1434
	if (addr > mm->free_area_cache)
		mm->free_area_cache = addr;
L
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	/* dont allow allocations above current base */
1437 1438
	if (mm->free_area_cache > mm->mmap_base)
		mm->free_area_cache = mm->mmap_base;
L
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}

unsigned long
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
1445 1446 1447 1448 1449 1450 1451 1452 1453
	unsigned long (*get_area)(struct file *, unsigned long,
				  unsigned long, unsigned long, unsigned long);

	get_area = current->mm->get_unmapped_area;
	if (file && file->f_op && file->f_op->get_unmapped_area)
		get_area = file->f_op->get_unmapped_area;
	addr = get_area(file, addr, len, pgoff, flags);
	if (IS_ERR_VALUE(addr))
		return addr;
L
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1455 1456 1457 1458
	if (addr > TASK_SIZE - len)
		return -ENOMEM;
	if (addr & ~PAGE_MASK)
		return -EINVAL;
1459

1460
	return arch_rebalance_pgtables(addr, len);
L
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}

EXPORT_SYMBOL(get_unmapped_area);

/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
Z
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struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
L
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{
	struct vm_area_struct *vma = NULL;

	if (mm) {
		/* Check the cache first. */
		/* (Cache hit rate is typically around 35%.) */
		vma = mm->mmap_cache;
		if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
			struct rb_node * rb_node;

			rb_node = mm->mm_rb.rb_node;
			vma = NULL;

			while (rb_node) {
				struct vm_area_struct * vma_tmp;

				vma_tmp = rb_entry(rb_node,
						struct vm_area_struct, vm_rb);

				if (vma_tmp->vm_end > addr) {
					vma = vma_tmp;
					if (vma_tmp->vm_start <= addr)
						break;
					rb_node = rb_node->rb_left;
				} else
					rb_node = rb_node->rb_right;
			}
			if (vma)
				mm->mmap_cache = vma;
		}
	}
	return vma;
}

EXPORT_SYMBOL(find_vma);

/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
struct vm_area_struct *
find_vma_prev(struct mm_struct *mm, unsigned long addr,
			struct vm_area_struct **pprev)
{
	struct vm_area_struct *vma = NULL, *prev = NULL;
Z
ZhenwenXu 已提交
1509
	struct rb_node *rb_node;
L
Linus Torvalds 已提交
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	if (!mm)
		goto out;

	/* Guard against addr being lower than the first VMA */
	vma = mm->mmap;

	/* Go through the RB tree quickly. */
	rb_node = mm->mm_rb.rb_node;

	while (rb_node) {
		struct vm_area_struct *vma_tmp;
		vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);

		if (addr < vma_tmp->vm_end) {
			rb_node = rb_node->rb_left;
		} else {
			prev = vma_tmp;
			if (!prev->vm_next || (addr < prev->vm_next->vm_end))
				break;
			rb_node = rb_node->rb_right;
		}
	}

out:
	*pprev = prev;
	return prev ? prev->vm_next : vma;
}

/*
 * Verify that the stack growth is acceptable and
 * update accounting. This is shared with both the
 * grow-up and grow-down cases.
 */
Z
ZhenwenXu 已提交
1543
static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
L
Linus Torvalds 已提交
1544 1545 1546
{
	struct mm_struct *mm = vma->vm_mm;
	struct rlimit *rlim = current->signal->rlim;
1547
	unsigned long new_start;
L
Linus Torvalds 已提交
1548 1549

	/* address space limit tests */
A
akpm@osdl.org 已提交
1550
	if (!may_expand_vm(mm, grow))
L
Linus Torvalds 已提交
1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566
		return -ENOMEM;

	/* Stack limit test */
	if (size > rlim[RLIMIT_STACK].rlim_cur)
		return -ENOMEM;

	/* mlock limit tests */
	if (vma->vm_flags & VM_LOCKED) {
		unsigned long locked;
		unsigned long limit;
		locked = mm->locked_vm + grow;
		limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
		if (locked > limit && !capable(CAP_IPC_LOCK))
			return -ENOMEM;
	}

1567 1568 1569 1570 1571 1572
	/* Check to ensure the stack will not grow into a hugetlb-only region */
	new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
			vma->vm_end - size;
	if (is_hugepage_only_range(vma->vm_mm, new_start, size))
		return -EFAULT;

L
Linus Torvalds 已提交
1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583
	/*
	 * Overcommit..  This must be the final test, as it will
	 * update security statistics.
	 */
	if (security_vm_enough_memory(grow))
		return -ENOMEM;

	/* Ok, everything looks good - let it rip */
	mm->total_vm += grow;
	if (vma->vm_flags & VM_LOCKED)
		mm->locked_vm += grow;
1584
	vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
L
Linus Torvalds 已提交
1585 1586 1587
	return 0;
}

H
Hugh Dickins 已提交
1588
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
L
Linus Torvalds 已提交
1589
/*
H
Hugh Dickins 已提交
1590 1591
 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
 * vma is the last one with address > vma->vm_end.  Have to extend vma.
L
Linus Torvalds 已提交
1592
 */
1593
#ifndef CONFIG_IA64
D
Denys Vlasenko 已提交
1594
static
H
Hugh Dickins 已提交
1595 1596
#endif
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
L
Linus Torvalds 已提交
1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614
{
	int error;

	if (!(vma->vm_flags & VM_GROWSUP))
		return -EFAULT;

	/*
	 * We must make sure the anon_vma is allocated
	 * so that the anon_vma locking is not a noop.
	 */
	if (unlikely(anon_vma_prepare(vma)))
		return -ENOMEM;
	anon_vma_lock(vma);

	/*
	 * vma->vm_start/vm_end cannot change under us because the caller
	 * is required to hold the mmap_sem in read mode.  We need the
	 * anon_vma lock to serialize against concurrent expand_stacks.
1615
	 * Also guard against wrapping around to address 0.
L
Linus Torvalds 已提交
1616
	 */
1617 1618 1619 1620 1621 1622
	if (address < PAGE_ALIGN(address+4))
		address = PAGE_ALIGN(address+4);
	else {
		anon_vma_unlock(vma);
		return -ENOMEM;
	}
L
Linus Torvalds 已提交
1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638
	error = 0;

	/* Somebody else might have raced and expanded it already */
	if (address > vma->vm_end) {
		unsigned long size, grow;

		size = address - vma->vm_start;
		grow = (address - vma->vm_end) >> PAGE_SHIFT;

		error = acct_stack_growth(vma, size, grow);
		if (!error)
			vma->vm_end = address;
	}
	anon_vma_unlock(vma);
	return error;
}
H
Hugh Dickins 已提交
1639 1640
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */

L
Linus Torvalds 已提交
1641 1642 1643
/*
 * vma is the first one with address < vma->vm_start.  Have to extend vma.
 */
D
Denys Vlasenko 已提交
1644
static int expand_downwards(struct vm_area_struct *vma,
1645
				   unsigned long address)
L
Linus Torvalds 已提交
1646 1647 1648 1649 1650 1651 1652 1653 1654
{
	int error;

	/*
	 * We must make sure the anon_vma is allocated
	 * so that the anon_vma locking is not a noop.
	 */
	if (unlikely(anon_vma_prepare(vma)))
		return -ENOMEM;
1655 1656

	address &= PAGE_MASK;
1657
	error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1658 1659 1660
	if (error)
		return error;

L
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1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685
	anon_vma_lock(vma);

	/*
	 * vma->vm_start/vm_end cannot change under us because the caller
	 * is required to hold the mmap_sem in read mode.  We need the
	 * anon_vma lock to serialize against concurrent expand_stacks.
	 */

	/* Somebody else might have raced and expanded it already */
	if (address < vma->vm_start) {
		unsigned long size, grow;

		size = vma->vm_end - address;
		grow = (vma->vm_start - address) >> PAGE_SHIFT;

		error = acct_stack_growth(vma, size, grow);
		if (!error) {
			vma->vm_start = address;
			vma->vm_pgoff -= grow;
		}
	}
	anon_vma_unlock(vma);
	return error;
}

1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705
int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
{
	return expand_downwards(vma, address);
}

#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
	return expand_upwards(vma, address);
}

struct vm_area_struct *
find_extend_vma(struct mm_struct *mm, unsigned long addr)
{
	struct vm_area_struct *vma, *prev;

	addr &= PAGE_MASK;
	vma = find_vma_prev(mm, addr, &prev);
	if (vma && (vma->vm_start <= addr))
		return vma;
1706
	if (!prev || expand_stack(prev, addr))
1707
		return NULL;
1708 1709 1710 1711
	if (prev->vm_flags & VM_LOCKED) {
		if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
			return NULL;	/* vma gone! */
	}
1712 1713 1714 1715 1716 1717 1718 1719
	return prev;
}
#else
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
	return expand_downwards(vma, address);
}

L
Linus Torvalds 已提交
1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736
struct vm_area_struct *
find_extend_vma(struct mm_struct * mm, unsigned long addr)
{
	struct vm_area_struct * vma;
	unsigned long start;

	addr &= PAGE_MASK;
	vma = find_vma(mm,addr);
	if (!vma)
		return NULL;
	if (vma->vm_start <= addr)
		return vma;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		return NULL;
	start = vma->vm_start;
	if (expand_stack(vma, addr))
		return NULL;
1737 1738 1739 1740
	if (vma->vm_flags & VM_LOCKED) {
		if (mlock_vma_pages_range(vma, addr, start) < 0)
			return NULL;	/* vma gone! */
	}
L
Linus Torvalds 已提交
1741 1742 1743 1744 1745
	return vma;
}
#endif

/*
1746
 * Ok - we have the memory areas we should free on the vma list,
L
Linus Torvalds 已提交
1747
 * so release them, and do the vma updates.
1748 1749
 *
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
1750
 */
1751
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
1752
{
1753 1754
	/* Update high watermark before we lower total_vm */
	update_hiwater_vm(mm);
L
Linus Torvalds 已提交
1755
	do {
1756 1757 1758 1759
		long nrpages = vma_pages(vma);

		mm->total_vm -= nrpages;
		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1760
		vma = remove_vma(vma);
1761
	} while (vma);
L
Linus Torvalds 已提交
1762 1763 1764 1765 1766 1767
	validate_mm(mm);
}

/*
 * Get rid of page table information in the indicated region.
 *
1768
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
1769 1770
 */
static void unmap_region(struct mm_struct *mm,
1771 1772
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end)
L
Linus Torvalds 已提交
1773
{
1774
	struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
L
Linus Torvalds 已提交
1775 1776 1777 1778 1779
	struct mmu_gather *tlb;
	unsigned long nr_accounted = 0;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
1780
	update_hiwater_rss(mm);
1781
	unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
L
Linus Torvalds 已提交
1782
	vm_unacct_memory(nr_accounted);
1783
	free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1784
				 next? next->vm_start: 0);
L
Linus Torvalds 已提交
1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797
	tlb_finish_mmu(tlb, start, end);
}

/*
 * Create a list of vma's touched by the unmap, removing them from the mm's
 * vma list as we go..
 */
static void
detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
	struct vm_area_struct *prev, unsigned long end)
{
	struct vm_area_struct **insertion_point;
	struct vm_area_struct *tail_vma = NULL;
1798
	unsigned long addr;
L
Linus Torvalds 已提交
1799 1800 1801 1802 1803 1804 1805 1806 1807 1808

	insertion_point = (prev ? &prev->vm_next : &mm->mmap);
	do {
		rb_erase(&vma->vm_rb, &mm->mm_rb);
		mm->map_count--;
		tail_vma = vma;
		vma = vma->vm_next;
	} while (vma && vma->vm_start < end);
	*insertion_point = vma;
	tail_vma->vm_next = NULL;
1809 1810 1811 1812 1813
	if (mm->unmap_area == arch_unmap_area)
		addr = prev ? prev->vm_end : mm->mmap_base;
	else
		addr = vma ?  vma->vm_start : mm->mmap_base;
	mm->unmap_area(mm, addr);
L
Linus Torvalds 已提交
1814 1815 1816 1817 1818
	mm->mmap_cache = NULL;		/* Kill the cache. */
}

/*
 * Split a vma into two pieces at address 'addr', a new vma is allocated
1819
 * either for the first part or the tail.
L
Linus Torvalds 已提交
1820 1821 1822 1823 1824 1825 1826
 */
int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
	      unsigned long addr, int new_below)
{
	struct mempolicy *pol;
	struct vm_area_struct *new;

1827 1828
	if (is_vm_hugetlb_page(vma) && (addr &
					~(huge_page_mask(hstate_vma(vma)))))
L
Linus Torvalds 已提交
1829 1830 1831 1832 1833
		return -EINVAL;

	if (mm->map_count >= sysctl_max_map_count)
		return -ENOMEM;

1834
	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847
	if (!new)
		return -ENOMEM;

	/* most fields are the same, copy all, and then fixup */
	*new = *vma;

	if (new_below)
		new->vm_end = addr;
	else {
		new->vm_start = addr;
		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
	}

1848
	pol = mpol_dup(vma_policy(vma));
L
Linus Torvalds 已提交
1849 1850 1851 1852 1853 1854
	if (IS_ERR(pol)) {
		kmem_cache_free(vm_area_cachep, new);
		return PTR_ERR(pol);
	}
	vma_set_policy(new, pol);

M
Matt Helsley 已提交
1855
	if (new->vm_file) {
L
Linus Torvalds 已提交
1856
		get_file(new->vm_file);
M
Matt Helsley 已提交
1857 1858 1859
		if (vma->vm_flags & VM_EXECUTABLE)
			added_exe_file_vma(mm);
	}
L
Linus Torvalds 已提交
1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880

	if (new->vm_ops && new->vm_ops->open)
		new->vm_ops->open(new);

	if (new_below)
		vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
			((addr - new->vm_start) >> PAGE_SHIFT), new);
	else
		vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);

	return 0;
}

/* Munmap is split into 2 main parts -- this part which finds
 * what needs doing, and the areas themselves, which do the
 * work.  This now handles partial unmappings.
 * Jeremy Fitzhardinge <jeremy@goop.org>
 */
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
{
	unsigned long end;
1881
	struct vm_area_struct *vma, *prev, *last;
L
Linus Torvalds 已提交
1882 1883 1884 1885 1886 1887 1888 1889

	if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
		return -EINVAL;

	if ((len = PAGE_ALIGN(len)) == 0)
		return -EINVAL;

	/* Find the first overlapping VMA */
1890 1891
	vma = find_vma_prev(mm, start, &prev);
	if (!vma)
L
Linus Torvalds 已提交
1892
		return 0;
1893
	/* we have  start < vma->vm_end  */
L
Linus Torvalds 已提交
1894 1895 1896

	/* if it doesn't overlap, we have nothing.. */
	end = start + len;
1897
	if (vma->vm_start >= end)
L
Linus Torvalds 已提交
1898 1899 1900 1901 1902 1903 1904 1905 1906
		return 0;

	/*
	 * If we need to split any vma, do it now to save pain later.
	 *
	 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
	 * unmapped vm_area_struct will remain in use: so lower split_vma
	 * places tmp vma above, and higher split_vma places tmp vma below.
	 */
1907 1908
	if (start > vma->vm_start) {
		int error = split_vma(mm, vma, start, 0);
L
Linus Torvalds 已提交
1909 1910
		if (error)
			return error;
1911
		prev = vma;
L
Linus Torvalds 已提交
1912 1913 1914 1915 1916 1917 1918 1919 1920
	}

	/* Does it split the last one? */
	last = find_vma(mm, end);
	if (last && end > last->vm_start) {
		int error = split_vma(mm, last, end, 1);
		if (error)
			return error;
	}
1921
	vma = prev? prev->vm_next: mm->mmap;
L
Linus Torvalds 已提交
1922

1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936
	/*
	 * unlock any mlock()ed ranges before detaching vmas
	 */
	if (mm->locked_vm) {
		struct vm_area_struct *tmp = vma;
		while (tmp && tmp->vm_start < end) {
			if (tmp->vm_flags & VM_LOCKED) {
				mm->locked_vm -= vma_pages(tmp);
				munlock_vma_pages_all(tmp);
			}
			tmp = tmp->vm_next;
		}
	}

L
Linus Torvalds 已提交
1937 1938 1939
	/*
	 * Remove the vma's, and unmap the actual pages
	 */
1940 1941
	detach_vmas_to_be_unmapped(mm, vma, prev, end);
	unmap_region(mm, vma, prev, start, end);
L
Linus Torvalds 已提交
1942 1943

	/* Fix up all other VM information */
1944
	remove_vma_list(mm, vma);
L
Linus Torvalds 已提交
1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965

	return 0;
}

EXPORT_SYMBOL(do_munmap);

asmlinkage long sys_munmap(unsigned long addr, size_t len)
{
	int ret;
	struct mm_struct *mm = current->mm;

	profile_munmap(addr);

	down_write(&mm->mmap_sem);
	ret = do_munmap(mm, addr, len);
	up_write(&mm->mmap_sem);
	return ret;
}

static inline void verify_mm_writelocked(struct mm_struct *mm)
{
1966
#ifdef CONFIG_DEBUG_VM
L
Linus Torvalds 已提交
1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985
	if (unlikely(down_read_trylock(&mm->mmap_sem))) {
		WARN_ON(1);
		up_read(&mm->mmap_sem);
	}
#endif
}

/*
 *  this is really a simplified "do_mmap".  it only handles
 *  anonymous maps.  eventually we may be able to do some
 *  brk-specific accounting here.
 */
unsigned long do_brk(unsigned long addr, unsigned long len)
{
	struct mm_struct * mm = current->mm;
	struct vm_area_struct * vma, * prev;
	unsigned long flags;
	struct rb_node ** rb_link, * rb_parent;
	pgoff_t pgoff = addr >> PAGE_SHIFT;
1986
	int error;
L
Linus Torvalds 已提交
1987 1988 1989 1990 1991 1992 1993 1994

	len = PAGE_ALIGN(len);
	if (!len)
		return addr;

	if ((addr + len) > TASK_SIZE || (addr + len) < addr)
		return -EINVAL;

1995 1996
	if (is_hugepage_only_range(mm, addr, len))
		return -EINVAL;
1997

1998
	error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
1999 2000 2001
	if (error)
		return error;

2002 2003 2004 2005 2006 2007
	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

	error = arch_mmap_check(addr, len, flags);
	if (error)
		return error;

L
Linus Torvalds 已提交
2008 2009 2010 2011 2012
	/*
	 * mlock MCL_FUTURE?
	 */
	if (mm->def_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
2013 2014
		locked = len >> PAGE_SHIFT;
		locked += mm->locked_vm;
L
Linus Torvalds 已提交
2015
		lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
2016
		lock_limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			return -EAGAIN;
	}

	/*
	 * mm->mmap_sem is required to protect against another thread
	 * changing the mappings in case we sleep.
	 */
	verify_mm_writelocked(mm);

	/*
	 * Clear old maps.  this also does some error checking for us
	 */
 munmap_back:
	vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
	if (vma && vma->vm_start < addr + len) {
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

	/* Check against address space limits *after* clearing old maps... */
A
akpm@osdl.org 已提交
2039
	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2040 2041 2042 2043 2044 2045 2046 2047 2048
		return -ENOMEM;

	if (mm->map_count > sysctl_max_map_count)
		return -ENOMEM;

	if (security_vm_enough_memory(len >> PAGE_SHIFT))
		return -ENOMEM;

	/* Can we just expand an old private anonymous mapping? */
2049 2050 2051
	vma = vma_merge(mm, prev, addr, addr + len, flags,
					NULL, NULL, pgoff, NULL);
	if (vma)
L
Linus Torvalds 已提交
2052 2053 2054 2055 2056
		goto out;

	/*
	 * create a vma struct for an anonymous mapping
	 */
P
Pekka Enberg 已提交
2057
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2058 2059 2060 2061 2062 2063 2064 2065 2066 2067
	if (!vma) {
		vm_unacct_memory(len >> PAGE_SHIFT);
		return -ENOMEM;
	}

	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;
	vma->vm_pgoff = pgoff;
	vma->vm_flags = flags;
2068
	vma->vm_page_prot = vm_get_page_prot(flags);
L
Linus Torvalds 已提交
2069 2070 2071 2072
	vma_link(mm, vma, prev, rb_link, rb_parent);
out:
	mm->total_vm += len >> PAGE_SHIFT;
	if (flags & VM_LOCKED) {
2073 2074
		if (!mlock_vma_pages_range(vma, addr, addr + len))
			mm->locked_vm += (len >> PAGE_SHIFT);
L
Linus Torvalds 已提交
2075 2076 2077 2078 2079 2080 2081 2082 2083 2084
	}
	return addr;
}

EXPORT_SYMBOL(do_brk);

/* Release all mmaps. */
void exit_mmap(struct mm_struct *mm)
{
	struct mmu_gather *tlb;
2085
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2086
	unsigned long nr_accounted = 0;
2087
	unsigned long end;
L
Linus Torvalds 已提交
2088

2089 2090
	/* mm's last user has gone, and its about to be pulled down */
	arch_exit_mmap(mm);
A
Andrea Arcangeli 已提交
2091
	mmu_notifier_release(mm);
2092

2093 2094 2095 2096 2097 2098 2099 2100 2101
	if (mm->locked_vm) {
		vma = mm->mmap;
		while (vma) {
			if (vma->vm_flags & VM_LOCKED)
				munlock_vma_pages_all(vma);
			vma = vma->vm_next;
		}
	}
	vma = mm->mmap;
L
Linus Torvalds 已提交
2102 2103
	lru_add_drain();
	flush_cache_mm(mm);
2104
	tlb = tlb_gather_mmu(mm, 1);
2105
	/* Don't update_hiwater_rss(mm) here, do_exit already did */
2106
	/* Use -1 here to ensure all VMAs in the mm are unmapped */
2107
	end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
L
Linus Torvalds 已提交
2108
	vm_unacct_memory(nr_accounted);
2109
	free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2110
	tlb_finish_mmu(tlb, 0, end);
L
Linus Torvalds 已提交
2111 2112

	/*
2113 2114
	 * Walk the list again, actually closing and freeing it,
	 * with preemption enabled, without holding any MM locks.
L
Linus Torvalds 已提交
2115
	 */
2116 2117
	while (vma)
		vma = remove_vma(vma);
2118

2119
	BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
L
Linus Torvalds 已提交
2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149
}

/* Insert vm structure into process list sorted by address
 * and into the inode's i_mmap tree.  If vm_file is non-NULL
 * then i_mmap_lock is taken here.
 */
int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
{
	struct vm_area_struct * __vma, * prev;
	struct rb_node ** rb_link, * rb_parent;

	/*
	 * The vm_pgoff of a purely anonymous vma should be irrelevant
	 * until its first write fault, when page's anon_vma and index
	 * are set.  But now set the vm_pgoff it will almost certainly
	 * end up with (unless mremap moves it elsewhere before that
	 * first wfault), so /proc/pid/maps tells a consistent story.
	 *
	 * By setting it to reflect the virtual start address of the
	 * vma, merges and splits can happen in a seamless way, just
	 * using the existing file pgoff checks and manipulations.
	 * Similarly in do_mmap_pgoff and in do_brk.
	 */
	if (!vma->vm_file) {
		BUG_ON(vma->anon_vma);
		vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
	}
	__vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
	if (__vma && __vma->vm_start < vma->vm_end)
		return -ENOMEM;
2150
	if ((vma->vm_flags & VM_ACCOUNT) &&
2151
	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
2152
		return -ENOMEM;
L
Linus Torvalds 已提交
2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188
	vma_link(mm, vma, prev, rb_link, rb_parent);
	return 0;
}

/*
 * Copy the vma structure to a new location in the same mm,
 * prior to moving page table entries, to effect an mremap move.
 */
struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
	unsigned long addr, unsigned long len, pgoff_t pgoff)
{
	struct vm_area_struct *vma = *vmap;
	unsigned long vma_start = vma->vm_start;
	struct mm_struct *mm = vma->vm_mm;
	struct vm_area_struct *new_vma, *prev;
	struct rb_node **rb_link, *rb_parent;
	struct mempolicy *pol;

	/*
	 * If anonymous vma has not yet been faulted, update new pgoff
	 * to match new location, to increase its chance of merging.
	 */
	if (!vma->vm_file && !vma->anon_vma)
		pgoff = addr >> PAGE_SHIFT;

	find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
	new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
			vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	if (new_vma) {
		/*
		 * Source vma may have been merged into new_vma
		 */
		if (vma_start >= new_vma->vm_start &&
		    vma_start < new_vma->vm_end)
			*vmap = new_vma;
	} else {
2189
		new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2190 2191
		if (new_vma) {
			*new_vma = *vma;
2192
			pol = mpol_dup(vma_policy(vma));
L
Linus Torvalds 已提交
2193 2194 2195 2196 2197 2198 2199 2200
			if (IS_ERR(pol)) {
				kmem_cache_free(vm_area_cachep, new_vma);
				return NULL;
			}
			vma_set_policy(new_vma, pol);
			new_vma->vm_start = addr;
			new_vma->vm_end = addr + len;
			new_vma->vm_pgoff = pgoff;
M
Matt Helsley 已提交
2201
			if (new_vma->vm_file) {
L
Linus Torvalds 已提交
2202
				get_file(new_vma->vm_file);
M
Matt Helsley 已提交
2203 2204 2205
				if (vma->vm_flags & VM_EXECUTABLE)
					added_exe_file_vma(mm);
			}
L
Linus Torvalds 已提交
2206 2207 2208 2209 2210 2211 2212
			if (new_vma->vm_ops && new_vma->vm_ops->open)
				new_vma->vm_ops->open(new_vma);
			vma_link(mm, new_vma, prev, rb_link, rb_parent);
		}
	}
	return new_vma;
}
A
akpm@osdl.org 已提交
2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228

/*
 * Return true if the calling process may expand its vm space by the passed
 * number of pages
 */
int may_expand_vm(struct mm_struct *mm, unsigned long npages)
{
	unsigned long cur = mm->total_vm;	/* pages */
	unsigned long lim;

	lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;

	if (cur + npages > lim)
		return 0;
	return 1;
}
2229 2230


N
Nick Piggin 已提交
2231 2232
static int special_mapping_fault(struct vm_area_struct *vma,
				struct vm_fault *vmf)
2233
{
N
Nick Piggin 已提交
2234
	pgoff_t pgoff;
2235 2236
	struct page **pages;

N
Nick Piggin 已提交
2237 2238 2239 2240 2241 2242 2243
	/*
	 * special mappings have no vm_file, and in that case, the mm
	 * uses vm_pgoff internally. So we have to subtract it from here.
	 * We are allowed to do this because we are the mm; do not copy
	 * this code into drivers!
	 */
	pgoff = vmf->pgoff - vma->vm_pgoff;
2244

N
Nick Piggin 已提交
2245 2246
	for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
		pgoff--;
2247 2248 2249 2250

	if (*pages) {
		struct page *page = *pages;
		get_page(page);
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		vmf->page = page;
		return 0;
2253 2254
	}

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	return VM_FAULT_SIGBUS;
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}

/*
 * Having a close hook prevents vma merging regardless of flags.
 */
static void special_mapping_close(struct vm_area_struct *vma)
{
}

static struct vm_operations_struct special_mapping_vmops = {
	.close = special_mapping_close,
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	.fault = special_mapping_fault,
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};

/*
 * Called with mm->mmap_sem held for writing.
 * Insert a new vma covering the given region, with the given flags.
 * Its pages are supplied by the given array of struct page *.
 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
 * The region past the last page supplied will always produce SIGBUS.
 * The array pointer and the pages it points to are assumed to stay alive
 * for as long as this mapping might exist.
 */
int install_special_mapping(struct mm_struct *mm,
			    unsigned long addr, unsigned long len,
			    unsigned long vm_flags, struct page **pages)
{
	struct vm_area_struct *vma;

	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (unlikely(vma == NULL))
		return -ENOMEM;

	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;

2293
	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2294
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
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	vma->vm_ops = &special_mapping_vmops;
	vma->vm_private_data = pages;

	if (unlikely(insert_vm_struct(mm, vma))) {
		kmem_cache_free(vm_area_cachep, vma);
		return -ENOMEM;
	}

	mm->total_vm += len >> PAGE_SHIFT;

	return 0;
}
2308 2309 2310

static DEFINE_MUTEX(mm_all_locks_mutex);

2311
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2312 2313 2314 2315 2316 2317
{
	if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) {
		/*
		 * The LSB of head.next can't change from under us
		 * because we hold the mm_all_locks_mutex.
		 */
2318
		spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem);
2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333
		/*
		 * We can safely modify head.next after taking the
		 * anon_vma->lock. If some other vma in this mm shares
		 * the same anon_vma we won't take it again.
		 *
		 * No need of atomic instructions here, head.next
		 * can't change from under us thanks to the
		 * anon_vma->lock.
		 */
		if (__test_and_set_bit(0, (unsigned long *)
				       &anon_vma->head.next))
			BUG();
	}
}

2334
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347
{
	if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
		/*
		 * AS_MM_ALL_LOCKS can't change from under us because
		 * we hold the mm_all_locks_mutex.
		 *
		 * Operations on ->flags have to be atomic because
		 * even if AS_MM_ALL_LOCKS is stable thanks to the
		 * mm_all_locks_mutex, there may be other cpus
		 * changing other bitflags in parallel to us.
		 */
		if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
			BUG();
2348
		spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
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	}
}

/*
 * This operation locks against the VM for all pte/vma/mm related
 * operations that could ever happen on a certain mm. This includes
 * vmtruncate, try_to_unmap, and all page faults.
 *
 * The caller must take the mmap_sem in write mode before calling
 * mm_take_all_locks(). The caller isn't allowed to release the
 * mmap_sem until mm_drop_all_locks() returns.
 *
 * mmap_sem in write mode is required in order to block all operations
 * that could modify pagetables and free pages without need of
 * altering the vma layout (for example populate_range() with
 * nonlinear vmas). It's also needed in write mode to avoid new
 * anon_vmas to be associated with existing vmas.
 *
 * A single task can't take more than one mm_take_all_locks() in a row
 * or it would deadlock.
 *
 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
 * mapping->flags avoid to take the same lock twice, if more than one
 * vma in this mm is backed by the same anon_vma or address_space.
 *
 * We can take all the locks in random order because the VM code
 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
 * takes more than one of them in a row. Secondly we're protected
 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
 *
 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
 * that may have to take thousand of locks.
 *
 * mm_take_all_locks() can fail if it's interrupted by signals.
 */
int mm_take_all_locks(struct mm_struct *mm)
{
	struct vm_area_struct *vma;
	int ret = -EINTR;

	BUG_ON(down_read_trylock(&mm->mmap_sem));

	mutex_lock(&mm_all_locks_mutex);

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (signal_pending(current))
			goto out_unlock;
		if (vma->vm_file && vma->vm_file->f_mapping)
2397
			vm_lock_mapping(mm, vma->vm_file->f_mapping);
2398
	}
2399 2400 2401 2402 2403 2404

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (signal_pending(current))
			goto out_unlock;
		if (vma->anon_vma)
			vm_lock_anon_vma(mm, vma->anon_vma);
2405
	}
2406

2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471
	ret = 0;

out_unlock:
	if (ret)
		mm_drop_all_locks(mm);

	return ret;
}

static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
{
	if (test_bit(0, (unsigned long *) &anon_vma->head.next)) {
		/*
		 * The LSB of head.next can't change to 0 from under
		 * us because we hold the mm_all_locks_mutex.
		 *
		 * We must however clear the bitflag before unlocking
		 * the vma so the users using the anon_vma->head will
		 * never see our bitflag.
		 *
		 * No need of atomic instructions here, head.next
		 * can't change from under us until we release the
		 * anon_vma->lock.
		 */
		if (!__test_and_clear_bit(0, (unsigned long *)
					  &anon_vma->head.next))
			BUG();
		spin_unlock(&anon_vma->lock);
	}
}

static void vm_unlock_mapping(struct address_space *mapping)
{
	if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
		/*
		 * AS_MM_ALL_LOCKS can't change to 0 from under us
		 * because we hold the mm_all_locks_mutex.
		 */
		spin_unlock(&mapping->i_mmap_lock);
		if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
					&mapping->flags))
			BUG();
	}
}

/*
 * The mmap_sem cannot be released by the caller until
 * mm_drop_all_locks() returns.
 */
void mm_drop_all_locks(struct mm_struct *mm)
{
	struct vm_area_struct *vma;

	BUG_ON(down_read_trylock(&mm->mmap_sem));
	BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (vma->anon_vma)
			vm_unlock_anon_vma(vma->anon_vma);
		if (vma->vm_file && vma->vm_file->f_mapping)
			vm_unlock_mapping(vma->vm_file->f_mapping);
	}

	mutex_unlock(&mm_all_locks_mutex);
}