mmap.c 85.7 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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 */

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#include <linux/kernel.h>
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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>
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#include <linux/export.h>
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#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 <linux/perf_event.h>
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#include <linux/audit.h>
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#include <linux/khugepaged.h>
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#include <linux/uprobes.h>
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#include <linux/rbtree_augmented.h>
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#include <linux/sched/sysctl.h>
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#include <linux/notifier.h>
#include <linux/memory.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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/* 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 __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
int sysctl_overcommit_ratio __read_mostly = 50;	/* default is 50% */
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int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
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unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
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unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
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/*
 * Make sure vm_committed_as in one cacheline and not cacheline shared with
 * other variables. It can be updated by several CPUs frequently.
 */
struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
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/*
 * The global memory commitment made in the system can be a metric
 * that can be used to drive ballooning decisions when Linux is hosted
 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
 * balancing memory across competing virtual machines that are hosted.
 * Several metrics drive this policy engine including the guest reported
 * memory commitment.
 */
unsigned long vm_memory_committed(void)
{
	return percpu_counter_read_positive(&vm_committed_as);
}
EXPORT_SYMBOL_GPL(vm_memory_committed);

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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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{
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	unsigned long free, allowed, reserve;
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	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) {
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		free = global_page_state(NR_FREE_PAGES);
		free += global_page_state(NR_FILE_PAGES);

		/*
		 * shmem pages shouldn't be counted as free in this
		 * case, they can't be purged, only swapped out, and
		 * that won't affect the overall amount of available
		 * memory in the system.
		 */
		free -= global_page_state(NR_SHMEM);
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		free += get_nr_swap_pages();
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		/*
		 * 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 reserved pages. The pages are not for anonymous pages.
		 */
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		if (free <= totalreserve_pages)
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			goto error;
		else
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			free -= totalreserve_pages;
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		/*
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		 * Reserve some for root
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		 */
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		if (!cap_sys_admin)
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			free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
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		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;
	/*
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	 * Reserve some for root
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	 */
	if (!cap_sys_admin)
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		allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
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	allowed += total_swap_pages;

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	/*
	 * Don't let a single process grow so big a user can't recover
	 */
	if (mm) {
		reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
		allowed -= min(mm->total_vm / 32, reserve);
	}
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	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
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		return 0;
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error:
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	vm_unacct_memory(pages);

	return -ENOMEM;
}

/*
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 * Requires inode->i_mapping->i_mmap_mutex
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 */
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_inode(file)->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))
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		list_del_init(&vma->shared.nonlinear);
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	else
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		vma_interval_tree_remove(vma, &mapping->i_mmap);
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	flush_dcache_mmap_unlock(mapping);
}

/*
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 * Unlink a file-based vm structure from its interval tree, to hide
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 * 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;
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		mutex_lock(&mapping->i_mmap_mutex);
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		__remove_shared_vm_struct(vma, file, mapping);
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		mutex_unlock(&mapping->i_mmap_mutex);
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	}
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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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	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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}

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static unsigned long do_brk(unsigned long addr, unsigned long len);

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SYSCALL_DEFINE1(brk, unsigned long, brk)
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{
	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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	bool populate;
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	down_write(&mm->mmap_sem);

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#ifdef CONFIG_COMPAT_BRK
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	/*
	 * CONFIG_COMPAT_BRK can still be overridden by setting
	 * randomize_va_space to 2, which will still cause mm->start_brk
	 * to be arbitrarily shifted
	 */
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	if (current->brk_randomized)
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		min_brk = mm->start_brk;
	else
		min_brk = mm->end_data;
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#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
	 */
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	rlim = rlimit(RLIMIT_DATA);
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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;
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set_brk:
	mm->brk = brk;
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	populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
	up_write(&mm->mmap_sem);
	if (populate)
		mm_populate(oldbrk, newbrk - oldbrk);
	return brk;

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out:
	retval = mm->brk;
	up_write(&mm->mmap_sem);
	return retval;
}

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static long vma_compute_subtree_gap(struct vm_area_struct *vma)
{
	unsigned long max, subtree_gap;
	max = vma->vm_start;
	if (vma->vm_prev)
		max -= vma->vm_prev->vm_end;
	if (vma->vm_rb.rb_left) {
		subtree_gap = rb_entry(vma->vm_rb.rb_left,
				struct vm_area_struct, vm_rb)->rb_subtree_gap;
		if (subtree_gap > max)
			max = subtree_gap;
	}
	if (vma->vm_rb.rb_right) {
		subtree_gap = rb_entry(vma->vm_rb.rb_right,
				struct vm_area_struct, vm_rb)->rb_subtree_gap;
		if (subtree_gap > max)
			max = subtree_gap;
	}
	return max;
}

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#ifdef CONFIG_DEBUG_VM_RB
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static int browse_rb(struct rb_root *root)
{
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	int i = 0, j, bug = 0;
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	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);
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		if (vma->vm_start < prev) {
			printk("vm_start %lx prev %lx\n", vma->vm_start, prev);
			bug = 1;
		}
		if (vma->vm_start < pend) {
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			printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
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			bug = 1;
		}
		if (vma->vm_start > vma->vm_end) {
			printk("vm_end %lx < vm_start %lx\n",
				vma->vm_end, vma->vm_start);
			bug = 1;
		}
		if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
			printk("free gap %lx, correct %lx\n",
			       vma->rb_subtree_gap,
			       vma_compute_subtree_gap(vma));
			bug = 1;
		}
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		i++;
		pn = nd;
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		prev = vma->vm_start;
		pend = vma->vm_end;
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	}
	j = 0;
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	for (nd = pn; nd; nd = rb_prev(nd))
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		j++;
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	if (i != j) {
		printk("backwards %d, forwards %d\n", j, i);
		bug = 1;
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	}
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	return bug ? -1 : i;
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}

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static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
{
	struct rb_node *nd;

	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);
		BUG_ON(vma != ignore &&
		       vma->rb_subtree_gap != vma_compute_subtree_gap(vma));
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	}
}

void validate_mm(struct mm_struct *mm)
{
	int bug = 0;
	int i = 0;
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	unsigned long highest_address = 0;
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	struct vm_area_struct *vma = mm->mmap;
	while (vma) {
		struct anon_vma_chain *avc;
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		vma_lock_anon_vma(vma);
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		list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
			anon_vma_interval_tree_verify(avc);
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		vma_unlock_anon_vma(vma);
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		highest_address = vma->vm_end;
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		vma = vma->vm_next;
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		i++;
	}
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	if (i != mm->map_count) {
		printk("map_count %d vm_next %d\n", mm->map_count, i);
		bug = 1;
	}
	if (highest_address != mm->highest_vm_end) {
		printk("mm->highest_vm_end %lx, found %lx\n",
		       mm->highest_vm_end, highest_address);
		bug = 1;
	}
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	i = browse_rb(&mm->mm_rb);
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	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
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#define validate_mm_rb(root, ignore) do { } while (0)
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#define validate_mm(mm) do { } while (0)
#endif

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RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
		     unsigned long, rb_subtree_gap, vma_compute_subtree_gap)

/*
 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
 * vma->vm_prev->vm_end values changed, without modifying the vma's position
 * in the rbtree.
 */
static void vma_gap_update(struct vm_area_struct *vma)
{
	/*
	 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
	 * function that does exacltly what we want.
	 */
	vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
}

static inline void vma_rb_insert(struct vm_area_struct *vma,
				 struct rb_root *root)
{
	/* All rb_subtree_gap values must be consistent prior to insertion */
	validate_mm_rb(root, NULL);

	rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
}

static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
{
	/*
	 * All rb_subtree_gap values must be consistent prior to erase,
	 * with the possible exception of the vma being erased.
	 */
	validate_mm_rb(root, vma);

	/*
	 * Note rb_erase_augmented is a fairly large inline function,
	 * so make sure we instantiate it only once with our desired
	 * augmented rbtree callbacks.
	 */
	rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
}

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/*
 * vma has some anon_vma assigned, and is already inserted on that
 * anon_vma's interval trees.
 *
 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
 * vma must be removed from the anon_vma's interval trees using
 * anon_vma_interval_tree_pre_update_vma().
 *
 * After the update, the vma will be reinserted using
 * anon_vma_interval_tree_post_update_vma().
 *
 * The entire update must be protected by exclusive mmap_sem and by
 * the root anon_vma's mutex.
 */
static inline void
anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
{
	struct anon_vma_chain *avc;

	list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
		anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
}

static inline void
anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
{
	struct anon_vma_chain *avc;

	list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
		anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
}

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static int find_vma_links(struct mm_struct *mm, unsigned long addr,
		unsigned long end, struct vm_area_struct **pprev,
		struct rb_node ***rb_link, struct rb_node **rb_parent)
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{
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	struct rb_node **__rb_link, *__rb_parent, *rb_prev;
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	__rb_link = &mm->mm_rb.rb_node;
	rb_prev = __rb_parent = 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) {
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			/* Fail if an existing vma overlaps the area */
			if (vma_tmp->vm_start < end)
				return -ENOMEM;
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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;
551
	return 0;
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}

554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581
static unsigned long count_vma_pages_range(struct mm_struct *mm,
		unsigned long addr, unsigned long end)
{
	unsigned long nr_pages = 0;
	struct vm_area_struct *vma;

	/* Find first overlaping mapping */
	vma = find_vma_intersection(mm, addr, end);
	if (!vma)
		return 0;

	nr_pages = (min(end, vma->vm_end) -
		max(addr, vma->vm_start)) >> PAGE_SHIFT;

	/* Iterate over the rest of the overlaps */
	for (vma = vma->vm_next; vma; vma = vma->vm_next) {
		unsigned long overlap_len;

		if (vma->vm_start > end)
			break;

		overlap_len = min(end, vma->vm_end) - vma->vm_start;
		nr_pages += overlap_len >> PAGE_SHIFT;
	}

	return nr_pages;
}

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void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
		struct rb_node **rb_link, struct rb_node *rb_parent)
{
585 586 587 588 589 590 591 592 593 594 595 596 597 598 599
	/* Update tracking information for the gap following the new vma. */
	if (vma->vm_next)
		vma_gap_update(vma->vm_next);
	else
		mm->highest_vm_end = vma->vm_end;

	/*
	 * vma->vm_prev wasn't known when we followed the rbtree to find the
	 * correct insertion point for that vma. As a result, we could not
	 * update the vma vm_rb parents rb_subtree_gap values on the way down.
	 * So, we first insert the vma with a zero rb_subtree_gap value
	 * (to be consistent with what we did on the way down), and then
	 * immediately update the gap to the correct value. Finally we
	 * rebalance the rbtree after all augmented values have been set.
	 */
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	rb_link_node(&vma->vm_rb, rb_parent, rb_link);
601 602 603
	vma->rb_subtree_gap = 0;
	vma_gap_update(vma);
	vma_rb_insert(vma, &mm->mm_rb);
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}

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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_inode(file)->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
623
			vma_interval_tree_insert(vma, &mapping->i_mmap);
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		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);
}

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;

646
	if (mapping)
647
		mutex_lock(&mapping->i_mmap_mutex);
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	__vma_link(mm, vma, prev, rb_link, rb_parent);
	__vma_link_file(vma);

	if (mapping)
653
		mutex_unlock(&mapping->i_mmap_mutex);
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	mm->map_count++;
	validate_mm(mm);
}

/*
660
 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
661
 * mm's list and rbtree.  It has already been inserted into the interval tree.
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 */
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static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
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{
665
	struct vm_area_struct *prev;
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	struct rb_node **rb_link, *rb_parent;
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668 669 670
	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
			   &prev, &rb_link, &rb_parent))
		BUG();
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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)
{
679
	struct vm_area_struct *next;
680

681 682
	vma_rb_erase(vma, &mm->mm_rb);
	prev->vm_next = next = vma->vm_next;
683 684
	if (next)
		next->vm_prev = prev;
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	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.
 */
696
int vma_adjust(struct vm_area_struct *vma, unsigned long start,
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	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;
703
	struct rb_root *root = NULL;
704
	struct anon_vma *anon_vma = NULL;
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	struct file *file = vma->vm_file;
706
	bool start_changed = false, end_changed = false;
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	long adjust_next = 0;
	int remove_next = 0;

	if (next && !insert) {
711 712
		struct vm_area_struct *exporter = NULL;

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		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;
720
			exporter = next;
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			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;
728
			exporter = next;
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			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);
737
			exporter = vma;
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			importer = next;
		}

741 742 743 744 745
		/*
		 * 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.
		 */
746 747
		if (exporter && exporter->anon_vma && !importer->anon_vma) {
			if (anon_vma_clone(importer, exporter))
748
				return -ENOMEM;
749
			importer->anon_vma = exporter->anon_vma;
750 751 752
		}
	}

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	if (file) {
		mapping = file->f_mapping;
755
		if (!(vma->vm_flags & VM_NONLINEAR)) {
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			root = &mapping->i_mmap;
757
			uprobe_munmap(vma, vma->vm_start, vma->vm_end);
758 759

			if (adjust_next)
760 761
				uprobe_munmap(next, next->vm_start,
							next->vm_end);
762 763
		}

764
		mutex_lock(&mapping->i_mmap_mutex);
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		if (insert) {
			/*
767
			 * Put into interval tree now, so instantiated pages
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			 * 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);
		}
	}

776 777
	vma_adjust_trans_huge(vma, start, end, adjust_next);

778 779 780 781
	anon_vma = vma->anon_vma;
	if (!anon_vma && adjust_next)
		anon_vma = next->anon_vma;
	if (anon_vma) {
782 783
		VM_BUG_ON(adjust_next && next->anon_vma &&
			  anon_vma != next->anon_vma);
784
		anon_vma_lock_write(anon_vma);
785 786 787 788
		anon_vma_interval_tree_pre_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_pre_update_vma(next);
	}
789

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	if (root) {
		flush_dcache_mmap_lock(mapping);
792
		vma_interval_tree_remove(vma, root);
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		if (adjust_next)
794
			vma_interval_tree_remove(next, root);
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	}

797 798 799 800 801 802 803 804
	if (start != vma->vm_start) {
		vma->vm_start = start;
		start_changed = true;
	}
	if (end != vma->vm_end) {
		vma->vm_end = end;
		end_changed = true;
	}
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	vma->vm_pgoff = pgoff;
	if (adjust_next) {
		next->vm_start += adjust_next << PAGE_SHIFT;
		next->vm_pgoff += adjust_next;
	}

	if (root) {
		if (adjust_next)
813 814
			vma_interval_tree_insert(next, root);
		vma_interval_tree_insert(vma, root);
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		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);
	} 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);
833 834 835 836 837 838 839 840 841
	} else {
		if (start_changed)
			vma_gap_update(vma);
		if (end_changed) {
			if (!next)
				mm->highest_vm_end = end;
			else if (!adjust_next)
				vma_gap_update(next);
		}
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	}

844 845 846 847
	if (anon_vma) {
		anon_vma_interval_tree_post_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_post_update_vma(next);
848
		anon_vma_unlock_write(anon_vma);
849
	}
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	if (mapping)
851
		mutex_unlock(&mapping->i_mmap_mutex);
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853
	if (root) {
854
		uprobe_mmap(vma);
855 856

		if (adjust_next)
857
			uprobe_mmap(next);
858 859
	}

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860
	if (remove_next) {
M
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861
		if (file) {
862
			uprobe_munmap(next, next->vm_start, next->vm_end);
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863
			fput(file);
M
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864
		}
865 866
		if (next->anon_vma)
			anon_vma_merge(vma, next);
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		mm->map_count--;
868
		mpol_put(vma_policy(next));
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869 870 871 872 873 874
		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.
		 */
875 876
		next = vma->vm_next;
		if (remove_next == 2)
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			goto again;
878 879 880 881
		else if (next)
			vma_gap_update(next);
		else
			mm->highest_vm_end = end;
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	}
883
	if (insert && file)
884
		uprobe_mmap(insert);
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	validate_mm(mm);
887 888

	return 0;
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}

/*
 * 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)
{
898
	if (vma->vm_flags ^ vm_flags)
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		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,
S
Shaohua Li 已提交
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					struct anon_vma *anon_vma2,
					struct vm_area_struct *vma)
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910
{
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Shaohua Li 已提交
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	/*
	 * The list_is_singular() test is to avoid merging VMA cloned from
	 * parents. This can improve scalability caused by anon_vma lock.
	 */
	if ((!anon_vma1 || !anon_vma2) && (!vma ||
		list_is_singular(&vma->anon_vma_chain)))
		return 1;
	return anon_vma1 == anon_vma2;
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919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936
}

/*
 * 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) &&
S
Shaohua Li 已提交
937
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
L
Linus Torvalds 已提交
938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955
		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) &&
S
Shaohua Li 已提交
956
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
L
Linus Torvalds 已提交
957
		pgoff_t vm_pglen;
958
		vm_pglen = vma_pages(vma);
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959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001
		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;
1002
	int err;
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1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033

	/*
	 * 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,
S
Shaohua Li 已提交
1034
						      next->anon_vma, NULL)) {
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1035
							/* cases 1, 6 */
1036
			err = vma_adjust(prev, prev->vm_start,
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1037 1038
				next->vm_end, prev->vm_pgoff, NULL);
		} else					/* cases 2, 5, 7 */
1039
			err = vma_adjust(prev, prev->vm_start,
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1040
				end, prev->vm_pgoff, NULL);
1041 1042
		if (err)
			return NULL;
A
Andrea Arcangeli 已提交
1043
		khugepaged_enter_vma_merge(prev);
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1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054
		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 */
1055
			err = vma_adjust(prev, prev->vm_start,
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1056 1057
				addr, prev->vm_pgoff, NULL);
		else					/* cases 3, 8 */
1058
			err = vma_adjust(area, addr, next->vm_end,
L
Linus Torvalds 已提交
1059
				next->vm_pgoff - pglen, NULL);
1060 1061
		if (err)
			return NULL;
A
Andrea Arcangeli 已提交
1062
		khugepaged_enter_vma_merge(area);
L
Linus Torvalds 已提交
1063 1064 1065 1066 1067 1068
		return area;
	}

	return NULL;
}

1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123
/*
 * Rough compatbility check to quickly see if it's even worth looking
 * at sharing an anon_vma.
 *
 * They need to have the same vm_file, and the flags can only differ
 * in things that mprotect may change.
 *
 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
 * we can merge the two vma's. For example, we refuse to merge a vma if
 * there is a vm_ops->close() function, because that indicates that the
 * driver is doing some kind of reference counting. But that doesn't
 * really matter for the anon_vma sharing case.
 */
static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
{
	return a->vm_end == b->vm_start &&
		mpol_equal(vma_policy(a), vma_policy(b)) &&
		a->vm_file == b->vm_file &&
		!((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
		b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
}

/*
 * Do some basic sanity checking to see if we can re-use the anon_vma
 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
 * the same as 'old', the other will be the new one that is trying
 * to share the anon_vma.
 *
 * NOTE! This runs with mm_sem held for reading, so it is possible that
 * the anon_vma of 'old' is concurrently in the process of being set up
 * by another page fault trying to merge _that_. But that's ok: if it
 * is being set up, that automatically means that it will be a singleton
 * acceptable for merging, so we can do all of this optimistically. But
 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
 *
 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
 * is to return an anon_vma that is "complex" due to having gone through
 * a fork).
 *
 * We also make sure that the two vma's are compatible (adjacent,
 * and with the same memory policies). That's all stable, even with just
 * a read lock on the mm_sem.
 */
static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
{
	if (anon_vma_compatible(a, b)) {
		struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);

		if (anon_vma && list_is_singular(&old->anon_vma_chain))
			return anon_vma;
	}
	return NULL;
}

L
Linus Torvalds 已提交
1124 1125 1126 1127 1128 1129 1130 1131 1132 1133
/*
 * 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)
{
1134
	struct anon_vma *anon_vma;
L
Linus Torvalds 已提交
1135 1136 1137 1138 1139 1140
	struct vm_area_struct *near;

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

1141 1142 1143
	anon_vma = reusable_anon_vma(near, vma, near);
	if (anon_vma)
		return anon_vma;
L
Linus Torvalds 已提交
1144
try_prev:
1145
	near = vma->vm_prev;
L
Linus Torvalds 已提交
1146 1147 1148
	if (!near)
		goto none;

1149 1150 1151
	anon_vma = reusable_anon_vma(near, near, vma);
	if (anon_vma)
		return anon_vma;
L
Linus Torvalds 已提交
1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164
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
1165
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
L
Linus Torvalds 已提交
1166 1167 1168 1169 1170
						struct file *file, long pages)
{
	const unsigned long stack_flags
		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);

1171 1172
	mm->total_vm += pages;

L
Linus Torvalds 已提交
1173 1174 1175 1176 1177 1178 1179 1180 1181
	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;
}
#endif /* CONFIG_PROC_FS */

A
Al Viro 已提交
1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194
/*
 * If a hint addr is less than mmap_min_addr change hint to be as
 * low as possible but still greater than mmap_min_addr
 */
static inline unsigned long round_hint_to_min(unsigned long hint)
{
	hint &= PAGE_MASK;
	if (((void *)hint != NULL) &&
	    (hint < mmap_min_addr))
		return PAGE_ALIGN(mmap_min_addr);
	return hint;
}

L
Linus Torvalds 已提交
1195
/*
1196
 * The caller must hold down_write(&current->mm->mmap_sem).
L
Linus Torvalds 已提交
1197 1198
 */

1199
unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
L
Linus Torvalds 已提交
1200
			unsigned long len, unsigned long prot,
1201
			unsigned long flags, unsigned long pgoff,
1202
			unsigned long *populate)
L
Linus Torvalds 已提交
1203 1204 1205
{
	struct mm_struct * mm = current->mm;
	struct inode *inode;
1206
	vm_flags_t vm_flags;
L
Linus Torvalds 已提交
1207

1208
	*populate = 0;
1209

L
Linus Torvalds 已提交
1210 1211 1212 1213 1214 1215 1216
	/*
	 * 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))
1217
		if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
L
Linus Torvalds 已提交
1218 1219 1220 1221 1222
			prot |= PROT_EXEC;

	if (!len)
		return -EINVAL;

1223 1224 1225
	if (!(flags & MAP_FIXED))
		addr = round_hint_to_min(addr);

L
Linus Torvalds 已提交
1226 1227
	/* Careful about overflows.. */
	len = PAGE_ALIGN(len);
1228
	if (!len)
L
Linus Torvalds 已提交
1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252
		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;

H
Huang Shijie 已提交
1253
	if (flags & MAP_LOCKED)
L
Linus Torvalds 已提交
1254 1255
		if (!can_do_mlock())
			return -EPERM;
1256

L
Linus Torvalds 已提交
1257 1258 1259
	/* mlock MCL_FUTURE? */
	if (vm_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
1260 1261
		locked = len >> PAGE_SHIFT;
		locked += mm->locked_vm;
J
Jiri Slaby 已提交
1262
		lock_limit = rlimit(RLIMIT_MEMLOCK);
1263
		lock_limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
1264 1265 1266 1267
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			return -EAGAIN;
	}

A
Al Viro 已提交
1268
	inode = file ? file_inode(file) : NULL;
L
Linus Torvalds 已提交
1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296

	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;
1297
			if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
L
Linus Torvalds 已提交
1298 1299 1300 1301 1302 1303 1304
				if (vm_flags & VM_EXEC)
					return -EPERM;
				vm_flags &= ~VM_MAYEXEC;
			}

			if (!file->f_op || !file->f_op->mmap)
				return -ENODEV;
L
Linus Torvalds 已提交
1305 1306 1307 1308 1309 1310 1311 1312
			break;

		default:
			return -EINVAL;
		}
	} else {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
1313 1314 1315 1316
			/*
			 * Ignore pgoff.
			 */
			pgoff = 0;
L
Linus Torvalds 已提交
1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329
			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;
		}
	}

1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344
	/*
	 * Set 'VM_NORESERVE' if we should not account for the
	 * memory use of this mapping.
	 */
	if (flags & MAP_NORESERVE) {
		/* We honor MAP_NORESERVE if allowed to overcommit */
		if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
			vm_flags |= VM_NORESERVE;

		/* hugetlb applies strict overcommit unless MAP_NORESERVE */
		if (file && is_file_hugepages(file))
			vm_flags |= VM_NORESERVE;
	}

	addr = mmap_region(file, addr, len, vm_flags, pgoff);
1345 1346 1347
	if (!IS_ERR_VALUE(addr) &&
	    ((vm_flags & VM_LOCKED) ||
	     (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1348
		*populate = len;
1349
	return addr;
M
Miklos Szeredi 已提交
1350
}
1351

H
Hugh Dickins 已提交
1352 1353 1354 1355 1356 1357 1358 1359
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
		unsigned long, prot, unsigned long, flags,
		unsigned long, fd, unsigned long, pgoff)
{
	struct file *file = NULL;
	unsigned long retval = -EBADF;

	if (!(flags & MAP_ANONYMOUS)) {
A
Al Viro 已提交
1360
		audit_mmap_fd(fd, flags);
H
Hugh Dickins 已提交
1361 1362 1363
		file = fget(fd);
		if (!file)
			goto out;
1364 1365
		if (is_file_hugepages(file))
			len = ALIGN(len, huge_page_size(hstate_file(file)));
1366 1367 1368
		retval = -EINVAL;
		if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
			goto out_fput;
H
Hugh Dickins 已提交
1369 1370
	} else if (flags & MAP_HUGETLB) {
		struct user_struct *user = NULL;
1371
		struct hstate *hs;
1372

1373
		hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1374 1375 1376 1377
		if (!hs)
			return -EINVAL;

		len = ALIGN(len, huge_page_size(hs));
H
Hugh Dickins 已提交
1378 1379 1380 1381 1382 1383
		/*
		 * VM_NORESERVE is used because the reservations will be
		 * taken when vm_ops->mmap() is called
		 * A dummy user value is used because we are not locking
		 * memory so no accounting is necessary
		 */
1384
		file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1385 1386 1387
				VM_NORESERVE,
				&user, HUGETLB_ANONHUGE_INODE,
				(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
H
Hugh Dickins 已提交
1388 1389 1390 1391 1392 1393
		if (IS_ERR(file))
			return PTR_ERR(file);
	}

	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);

A
Al Viro 已提交
1394
	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1395
out_fput:
H
Hugh Dickins 已提交
1396 1397 1398 1399 1400 1401
	if (file)
		fput(file);
out:
	return retval;
}

C
Christoph Hellwig 已提交
1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425
#ifdef __ARCH_WANT_SYS_OLD_MMAP
struct mmap_arg_struct {
	unsigned long addr;
	unsigned long len;
	unsigned long prot;
	unsigned long flags;
	unsigned long fd;
	unsigned long offset;
};

SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
{
	struct mmap_arg_struct a;

	if (copy_from_user(&a, arg, sizeof(a)))
		return -EFAULT;
	if (a.offset & ~PAGE_MASK)
		return -EINVAL;

	return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
			      a.offset >> PAGE_SHIFT);
}
#endif /* __ARCH_WANT_SYS_OLD_MMAP */

A
Alexey Dobriyan 已提交
1426 1427 1428 1429 1430 1431 1432 1433
/*
 * 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)
{
1434
	vm_flags_t vm_flags = vma->vm_flags;
A
Alexey Dobriyan 已提交
1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445

	/* 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) !=
1446
	    pgprot_val(vm_get_page_prot(vm_flags)))
A
Alexey Dobriyan 已提交
1447 1448 1449
		return 0;

	/* Specialty mapping? */
1450
	if (vm_flags & VM_PFNMAP)
A
Alexey Dobriyan 已提交
1451 1452 1453 1454 1455 1456 1457
		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);
}

1458 1459
/*
 * We account for memory if it's a private writeable mapping,
1460
 * not hugepages and VM_NORESERVE wasn't set.
1461
 */
1462
static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1463
{
1464 1465 1466 1467 1468 1469 1470
	/*
	 * hugetlb has its own accounting separate from the core VM
	 * VM_HUGETLB may not be set yet so we cannot check for that flag.
	 */
	if (file && is_file_hugepages(file))
		return 0;

1471 1472 1473
	return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
}

M
Miklos Szeredi 已提交
1474
unsigned long mmap_region(struct file *file, unsigned long addr,
1475
		unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
M
Miklos Szeredi 已提交
1476 1477 1478 1479 1480 1481 1482
{
	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;
A
Al Viro 已提交
1483
	struct inode *inode =  file ? file_inode(file) : NULL;
M
Miklos Szeredi 已提交
1484

1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501
	/* Check against address space limit. */
	if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
		unsigned long nr_pages;

		/*
		 * MAP_FIXED may remove pages of mappings that intersects with
		 * requested mapping. Account for the pages it would unmap.
		 */
		if (!(vm_flags & MAP_FIXED))
			return -ENOMEM;

		nr_pages = count_vma_pages_range(mm, addr, addr + len);

		if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages))
			return -ENOMEM;
	}

L
Linus Torvalds 已提交
1502 1503 1504
	/* Clear old maps */
	error = -ENOMEM;
munmap_back:
1505
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
L
Linus Torvalds 已提交
1506 1507 1508 1509 1510
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

1511 1512 1513
	/*
	 * Private writable mapping: check memory availability
	 */
1514
	if (accountable_mapping(file, vm_flags)) {
1515
		charged = len >> PAGE_SHIFT;
1516
		if (security_vm_enough_memory_mm(mm, charged))
1517 1518
			return -ENOMEM;
		vm_flags |= VM_ACCOUNT;
L
Linus Torvalds 已提交
1519 1520 1521
	}

	/*
1522
	 * Can we just expand an old mapping?
L
Linus Torvalds 已提交
1523
	 */
1524 1525 1526
	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
	if (vma)
		goto out;
L
Linus Torvalds 已提交
1527 1528 1529 1530 1531 1532

	/*
	 * 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
1533
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
1534 1535 1536 1537 1538 1539 1540 1541 1542
	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;
1543
	vma->vm_page_prot = vm_get_page_prot(vm_flags);
L
Linus Torvalds 已提交
1544
	vma->vm_pgoff = pgoff;
1545
	INIT_LIST_HEAD(&vma->anon_vma_chain);
L
Linus Torvalds 已提交
1546

1547 1548
	error = -EINVAL;	/* when rejecting VM_GROWSDOWN|VM_GROWSUP */

L
Linus Torvalds 已提交
1549 1550 1551 1552 1553 1554 1555 1556 1557
	if (file) {
		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;
		}
A
Al Viro 已提交
1558
		vma->vm_file = get_file(file);
L
Linus Torvalds 已提交
1559 1560 1561
		error = file->f_op->mmap(file, vma);
		if (error)
			goto unmap_and_free_vma;
1562 1563 1564 1565 1566

		/* Can addr have changed??
		 *
		 * Answer: Yes, several device drivers can do it in their
		 *         f_op->mmap method. -DaveM
1567 1568
		 * Bug: If addr is changed, prev, rb_link, rb_parent should
		 *      be updated for vma_link()
1569
		 */
1570 1571
		WARN_ON_ONCE(addr != vma->vm_start);

1572 1573 1574
		addr = vma->vm_start;
		pgoff = vma->vm_pgoff;
		vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
1575
	} else if (vm_flags & VM_SHARED) {
1576 1577
		if (unlikely(vm_flags & (VM_GROWSDOWN|VM_GROWSUP)))
			goto free_vma;
L
Linus Torvalds 已提交
1578 1579 1580 1581 1582
		error = shmem_zero_setup(vma);
		if (error)
			goto free_vma;
	}

1583 1584 1585 1586 1587 1588 1589 1590 1591 1592
	if (vma_wants_writenotify(vma)) {
		pgprot_t pprot = vma->vm_page_prot;

		/* Can vma->vm_page_prot have changed??
		 *
		 * Answer: Yes, drivers may have changed it in their
		 *         f_op->mmap method.
		 *
		 * Ensures that vmas marked as uncached stay that way.
		 */
1593
		vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1594 1595 1596
		if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
			vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	}
1597

1598 1599
	vma_link(mm, vma, prev, rb_link, rb_parent);
	file = vma->vm_file;
1600 1601 1602 1603 1604

	/* Once vma denies write, undo our temporary denial count */
	if (correct_wcount)
		atomic_inc(&inode->i_writecount);
out:
1605
	perf_event_mmap(vma);
1606

1607
	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
L
Linus Torvalds 已提交
1608
	if (vm_flags & VM_LOCKED) {
1609 1610
		if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
					vma == get_gate_vma(current->mm)))
1611
			mm->locked_vm += (len >> PAGE_SHIFT);
1612 1613 1614
		else
			vma->vm_flags &= ~VM_LOCKED;
	}
1615

1616 1617
	if (file)
		uprobe_mmap(vma);
1618

L
Linus Torvalds 已提交
1619 1620 1621 1622 1623 1624 1625 1626 1627
	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. */
1628 1629
	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
	charged = 0;
L
Linus Torvalds 已提交
1630 1631 1632 1633 1634 1635 1636 1637
free_vma:
	kmem_cache_free(vm_area_cachep, vma);
unacct_error:
	if (charged)
		vm_unacct_memory(charged);
	return error;
}

1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 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 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837
unsigned long unmapped_area(struct vm_unmapped_area_info *info)
{
	/*
	 * We implement the search by looking for an rbtree node that
	 * immediately follows a suitable gap. That is,
	 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
	 * - gap_end   = vma->vm_start        >= info->low_limit  + length;
	 * - gap_end - gap_start >= length
	 */

	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long length, low_limit, high_limit, gap_start, gap_end;

	/* Adjust search length to account for worst case alignment overhead */
	length = info->length + info->align_mask;
	if (length < info->length)
		return -ENOMEM;

	/* Adjust search limits by the desired length */
	if (info->high_limit < length)
		return -ENOMEM;
	high_limit = info->high_limit - length;

	if (info->low_limit > high_limit)
		return -ENOMEM;
	low_limit = info->low_limit + length;

	/* Check if rbtree root looks promising */
	if (RB_EMPTY_ROOT(&mm->mm_rb))
		goto check_highest;
	vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
	if (vma->rb_subtree_gap < length)
		goto check_highest;

	while (true) {
		/* Visit left subtree if it looks promising */
		gap_end = vma->vm_start;
		if (gap_end >= low_limit && vma->vm_rb.rb_left) {
			struct vm_area_struct *left =
				rb_entry(vma->vm_rb.rb_left,
					 struct vm_area_struct, vm_rb);
			if (left->rb_subtree_gap >= length) {
				vma = left;
				continue;
			}
		}

		gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
check_current:
		/* Check if current node has a suitable gap */
		if (gap_start > high_limit)
			return -ENOMEM;
		if (gap_end >= low_limit && gap_end - gap_start >= length)
			goto found;

		/* Visit right subtree if it looks promising */
		if (vma->vm_rb.rb_right) {
			struct vm_area_struct *right =
				rb_entry(vma->vm_rb.rb_right,
					 struct vm_area_struct, vm_rb);
			if (right->rb_subtree_gap >= length) {
				vma = right;
				continue;
			}
		}

		/* Go back up the rbtree to find next candidate node */
		while (true) {
			struct rb_node *prev = &vma->vm_rb;
			if (!rb_parent(prev))
				goto check_highest;
			vma = rb_entry(rb_parent(prev),
				       struct vm_area_struct, vm_rb);
			if (prev == vma->vm_rb.rb_left) {
				gap_start = vma->vm_prev->vm_end;
				gap_end = vma->vm_start;
				goto check_current;
			}
		}
	}

check_highest:
	/* Check highest gap, which does not precede any rbtree node */
	gap_start = mm->highest_vm_end;
	gap_end = ULONG_MAX;  /* Only for VM_BUG_ON below */
	if (gap_start > high_limit)
		return -ENOMEM;

found:
	/* We found a suitable gap. Clip it with the original low_limit. */
	if (gap_start < info->low_limit)
		gap_start = info->low_limit;

	/* Adjust gap address to the desired alignment */
	gap_start += (info->align_offset - gap_start) & info->align_mask;

	VM_BUG_ON(gap_start + info->length > info->high_limit);
	VM_BUG_ON(gap_start + info->length > gap_end);
	return gap_start;
}

unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;
	unsigned long length, low_limit, high_limit, gap_start, gap_end;

	/* Adjust search length to account for worst case alignment overhead */
	length = info->length + info->align_mask;
	if (length < info->length)
		return -ENOMEM;

	/*
	 * Adjust search limits by the desired length.
	 * See implementation comment at top of unmapped_area().
	 */
	gap_end = info->high_limit;
	if (gap_end < length)
		return -ENOMEM;
	high_limit = gap_end - length;

	if (info->low_limit > high_limit)
		return -ENOMEM;
	low_limit = info->low_limit + length;

	/* Check highest gap, which does not precede any rbtree node */
	gap_start = mm->highest_vm_end;
	if (gap_start <= high_limit)
		goto found_highest;

	/* Check if rbtree root looks promising */
	if (RB_EMPTY_ROOT(&mm->mm_rb))
		return -ENOMEM;
	vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
	if (vma->rb_subtree_gap < length)
		return -ENOMEM;

	while (true) {
		/* Visit right subtree if it looks promising */
		gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
		if (gap_start <= high_limit && vma->vm_rb.rb_right) {
			struct vm_area_struct *right =
				rb_entry(vma->vm_rb.rb_right,
					 struct vm_area_struct, vm_rb);
			if (right->rb_subtree_gap >= length) {
				vma = right;
				continue;
			}
		}

check_current:
		/* Check if current node has a suitable gap */
		gap_end = vma->vm_start;
		if (gap_end < low_limit)
			return -ENOMEM;
		if (gap_start <= high_limit && gap_end - gap_start >= length)
			goto found;

		/* Visit left subtree if it looks promising */
		if (vma->vm_rb.rb_left) {
			struct vm_area_struct *left =
				rb_entry(vma->vm_rb.rb_left,
					 struct vm_area_struct, vm_rb);
			if (left->rb_subtree_gap >= length) {
				vma = left;
				continue;
			}
		}

		/* Go back up the rbtree to find next candidate node */
		while (true) {
			struct rb_node *prev = &vma->vm_rb;
			if (!rb_parent(prev))
				return -ENOMEM;
			vma = rb_entry(rb_parent(prev),
				       struct vm_area_struct, vm_rb);
			if (prev == vma->vm_rb.rb_right) {
				gap_start = vma->vm_prev ?
					vma->vm_prev->vm_end : 0;
				goto check_current;
			}
		}
	}

found:
	/* We found a suitable gap. Clip it with the original high_limit. */
	if (gap_end > info->high_limit)
		gap_end = info->high_limit;

found_highest:
	/* Compute highest gap address at the desired alignment */
	gap_end -= info->length;
	gap_end -= (gap_end - info->align_offset) & info->align_mask;

	VM_BUG_ON(gap_end < info->low_limit);
	VM_BUG_ON(gap_end < gap_start);
	return gap_end;
}

L
Linus Torvalds 已提交
1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855
/* 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;
1856
	struct vm_unmapped_area_info info;
L
Linus Torvalds 已提交
1857 1858 1859 1860

	if (len > TASK_SIZE)
		return -ENOMEM;

1861 1862 1863
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1864 1865 1866 1867 1868 1869 1870 1871
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
		if (TASK_SIZE - len >= addr &&
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}

1872 1873 1874 1875 1876 1877
	info.flags = 0;
	info.length = len;
	info.low_limit = TASK_UNMAPPED_BASE;
	info.high_limit = TASK_SIZE;
	info.align_mask = 0;
	return vm_unmapped_area(&info);
L
Linus Torvalds 已提交
1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892
}
#endif	

/*
 * 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;
1893 1894
	unsigned long addr = addr0;
	struct vm_unmapped_area_info info;
L
Linus Torvalds 已提交
1895 1896 1897 1898 1899

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

1900 1901 1902
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1903 1904 1905 1906 1907 1908 1909 1910 1911
	/* 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;
	}

1912 1913 1914 1915 1916 1917
	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
	info.low_limit = PAGE_SIZE;
	info.high_limit = mm->mmap_base;
	info.align_mask = 0;
	addr = vm_unmapped_area(&info);
1918

L
Linus Torvalds 已提交
1919 1920 1921 1922 1923 1924
	/*
	 * 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.
	 */
1925 1926 1927 1928 1929 1930 1931
	if (addr & ~PAGE_MASK) {
		VM_BUG_ON(addr != -ENOMEM);
		info.flags = 0;
		info.low_limit = TASK_UNMAPPED_BASE;
		info.high_limit = TASK_SIZE;
		addr = vm_unmapped_area(&info);
	}
L
Linus Torvalds 已提交
1932 1933 1934 1935 1936 1937 1938 1939 1940

	return addr;
}
#endif

unsigned long
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
1941 1942 1943
	unsigned long (*get_area)(struct file *, unsigned long,
				  unsigned long, unsigned long, unsigned long);

1944 1945 1946 1947 1948 1949 1950 1951
	unsigned long error = arch_mmap_check(addr, len, flags);
	if (error)
		return error;

	/* Careful about overflows.. */
	if (len > TASK_SIZE)
		return -ENOMEM;

1952 1953 1954 1955 1956 1957
	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
Linus Torvalds 已提交
1958

1959 1960 1961 1962
	if (addr > TASK_SIZE - len)
		return -ENOMEM;
	if (addr & ~PAGE_MASK)
		return -EINVAL;
1963

1964 1965 1966
	addr = arch_rebalance_pgtables(addr, len);
	error = security_mmap_addr(addr);
	return error ? error : addr;
L
Linus Torvalds 已提交
1967 1968 1969 1970 1971
}

EXPORT_SYMBOL(get_unmapped_area);

/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
Z
ZhenwenXu 已提交
1972
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1973 1974 1975
{
	struct vm_area_struct *vma = NULL;

1976 1977
	/* Check the cache first. */
	/* (Cache hit rate is typically around 35%.) */
1978
	vma = ACCESS_ONCE(mm->mmap_cache);
1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997
	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;
L
Linus Torvalds 已提交
1998
		}
1999 2000
		if (vma)
			mm->mmap_cache = vma;
L
Linus Torvalds 已提交
2001 2002 2003 2004 2005 2006
	}
	return vma;
}

EXPORT_SYMBOL(find_vma);

K
KOSAKI Motohiro 已提交
2007 2008 2009
/*
 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
 */
L
Linus Torvalds 已提交
2010 2011 2012 2013
struct vm_area_struct *
find_vma_prev(struct mm_struct *mm, unsigned long addr,
			struct vm_area_struct **pprev)
{
K
KOSAKI Motohiro 已提交
2014
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2015

K
KOSAKI Motohiro 已提交
2016
	vma = find_vma(mm, addr);
M
Mikulas Patocka 已提交
2017 2018 2019 2020 2021 2022 2023 2024 2025 2026
	if (vma) {
		*pprev = vma->vm_prev;
	} else {
		struct rb_node *rb_node = mm->mm_rb.rb_node;
		*pprev = NULL;
		while (rb_node) {
			*pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
			rb_node = rb_node->rb_right;
		}
	}
K
KOSAKI Motohiro 已提交
2027
	return vma;
L
Linus Torvalds 已提交
2028 2029 2030 2031 2032 2033 2034
}

/*
 * 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
2035
static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
L
Linus Torvalds 已提交
2036 2037 2038
{
	struct mm_struct *mm = vma->vm_mm;
	struct rlimit *rlim = current->signal->rlim;
2039
	unsigned long new_start;
L
Linus Torvalds 已提交
2040 2041

	/* address space limit tests */
A
akpm@osdl.org 已提交
2042
	if (!may_expand_vm(mm, grow))
L
Linus Torvalds 已提交
2043 2044 2045
		return -ENOMEM;

	/* Stack limit test */
J
Jiri Slaby 已提交
2046
	if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
L
Linus Torvalds 已提交
2047 2048 2049 2050 2051 2052 2053
		return -ENOMEM;

	/* mlock limit tests */
	if (vma->vm_flags & VM_LOCKED) {
		unsigned long locked;
		unsigned long limit;
		locked = mm->locked_vm + grow;
J
Jiri Slaby 已提交
2054 2055
		limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
		limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
2056 2057 2058 2059
		if (locked > limit && !capable(CAP_IPC_LOCK))
			return -ENOMEM;
	}

2060 2061 2062 2063 2064 2065
	/* 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
2066 2067 2068 2069
	/*
	 * Overcommit..  This must be the final test, as it will
	 * update security statistics.
	 */
2070
	if (security_vm_enough_memory_mm(mm, grow))
L
Linus Torvalds 已提交
2071 2072 2073 2074 2075
		return -ENOMEM;

	/* Ok, everything looks good - let it rip */
	if (vma->vm_flags & VM_LOCKED)
		mm->locked_vm += grow;
2076
	vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
L
Linus Torvalds 已提交
2077 2078 2079
	return 0;
}

H
Hugh Dickins 已提交
2080
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
L
Linus Torvalds 已提交
2081
/*
H
Hugh Dickins 已提交
2082 2083
 * 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
2084
 */
H
Hugh Dickins 已提交
2085
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
L
Linus Torvalds 已提交
2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097
{
	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;
2098
	vma_lock_anon_vma(vma);
L
Linus Torvalds 已提交
2099 2100 2101 2102 2103

	/*
	 * 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.
2104
	 * Also guard against wrapping around to address 0.
L
Linus Torvalds 已提交
2105
	 */
2106 2107 2108
	if (address < PAGE_ALIGN(address+4))
		address = PAGE_ALIGN(address+4);
	else {
2109
		vma_unlock_anon_vma(vma);
2110 2111
		return -ENOMEM;
	}
L
Linus Torvalds 已提交
2112 2113 2114 2115 2116 2117 2118 2119 2120
	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;

2121 2122 2123 2124
		error = -ENOMEM;
		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
			error = acct_stack_growth(vma, size, grow);
			if (!error) {
2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136
				/*
				 * vma_gap_update() doesn't support concurrent
				 * updates, but we only hold a shared mmap_sem
				 * lock here, so we need to protect against
				 * concurrent vma expansions.
				 * vma_lock_anon_vma() doesn't help here, as
				 * we don't guarantee that all growable vmas
				 * in a mm share the same root anon vma.
				 * So, we reuse mm->page_table_lock to guard
				 * against concurrent vma expansions.
				 */
				spin_lock(&vma->vm_mm->page_table_lock);
2137
				anon_vma_interval_tree_pre_update_vma(vma);
2138
				vma->vm_end = address;
2139
				anon_vma_interval_tree_post_update_vma(vma);
2140 2141 2142 2143
				if (vma->vm_next)
					vma_gap_update(vma->vm_next);
				else
					vma->vm_mm->highest_vm_end = address;
2144 2145
				spin_unlock(&vma->vm_mm->page_table_lock);

2146 2147
				perf_event_mmap(vma);
			}
2148
		}
L
Linus Torvalds 已提交
2149
	}
2150
	vma_unlock_anon_vma(vma);
A
Andrea Arcangeli 已提交
2151
	khugepaged_enter_vma_merge(vma);
2152
	validate_mm(vma->vm_mm);
L
Linus Torvalds 已提交
2153 2154
	return error;
}
H
Hugh Dickins 已提交
2155 2156
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */

L
Linus Torvalds 已提交
2157 2158 2159
/*
 * vma is the first one with address < vma->vm_start.  Have to extend vma.
 */
2160
int expand_downwards(struct vm_area_struct *vma,
2161
				   unsigned long address)
L
Linus Torvalds 已提交
2162 2163 2164 2165 2166 2167 2168 2169 2170
{
	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;
2171 2172

	address &= PAGE_MASK;
2173
	error = security_mmap_addr(address);
2174 2175 2176
	if (error)
		return error;

2177
	vma_lock_anon_vma(vma);
L
Linus Torvalds 已提交
2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191

	/*
	 * 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;

2192 2193 2194 2195
		error = -ENOMEM;
		if (grow <= vma->vm_pgoff) {
			error = acct_stack_growth(vma, size, grow);
			if (!error) {
2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207
				/*
				 * vma_gap_update() doesn't support concurrent
				 * updates, but we only hold a shared mmap_sem
				 * lock here, so we need to protect against
				 * concurrent vma expansions.
				 * vma_lock_anon_vma() doesn't help here, as
				 * we don't guarantee that all growable vmas
				 * in a mm share the same root anon vma.
				 * So, we reuse mm->page_table_lock to guard
				 * against concurrent vma expansions.
				 */
				spin_lock(&vma->vm_mm->page_table_lock);
2208
				anon_vma_interval_tree_pre_update_vma(vma);
2209 2210
				vma->vm_start = address;
				vma->vm_pgoff -= grow;
2211
				anon_vma_interval_tree_post_update_vma(vma);
2212
				vma_gap_update(vma);
2213 2214
				spin_unlock(&vma->vm_mm->page_table_lock);

2215 2216
				perf_event_mmap(vma);
			}
L
Linus Torvalds 已提交
2217 2218
		}
	}
2219
	vma_unlock_anon_vma(vma);
A
Andrea Arcangeli 已提交
2220
	khugepaged_enter_vma_merge(vma);
2221
	validate_mm(vma->vm_mm);
L
Linus Torvalds 已提交
2222 2223 2224
	return error;
}

2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235
/*
 * Note how expand_stack() refuses to expand the stack all the way to
 * abut the next virtual mapping, *unless* that mapping itself is also
 * a stack mapping. We want to leave room for a guard page, after all
 * (the guard page itself is not added here, that is done by the
 * actual page faulting logic)
 *
 * This matches the behavior of the guard page logic (see mm/memory.c:
 * check_stack_guard_page()), which only allows the guard page to be
 * removed under these circumstances.
 */
2236 2237 2238
#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
2239 2240 2241 2242 2243 2244 2245 2246
	struct vm_area_struct *next;

	address &= PAGE_MASK;
	next = vma->vm_next;
	if (next && next->vm_start == address + PAGE_SIZE) {
		if (!(next->vm_flags & VM_GROWSUP))
			return -ENOMEM;
	}
2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258
	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;
2259
	if (!prev || expand_stack(prev, addr))
2260
		return NULL;
2261 2262
	if (prev->vm_flags & VM_LOCKED)
		__mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);
2263 2264 2265 2266 2267
	return prev;
}
#else
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
2268 2269 2270 2271 2272 2273 2274 2275
	struct vm_area_struct *prev;

	address &= PAGE_MASK;
	prev = vma->vm_prev;
	if (prev && prev->vm_end == address) {
		if (!(prev->vm_flags & VM_GROWSDOWN))
			return -ENOMEM;
	}
2276 2277 2278
	return expand_downwards(vma, address);
}

L
Linus Torvalds 已提交
2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295
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;
2296 2297
	if (vma->vm_flags & VM_LOCKED)
		__mlock_vma_pages_range(vma, addr, start, NULL);
L
Linus Torvalds 已提交
2298 2299 2300 2301 2302
	return vma;
}
#endif

/*
2303
 * Ok - we have the memory areas we should free on the vma list,
L
Linus Torvalds 已提交
2304
 * so release them, and do the vma updates.
2305 2306
 *
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
2307
 */
2308
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
2309
{
2310 2311
	unsigned long nr_accounted = 0;

2312 2313
	/* Update high watermark before we lower total_vm */
	update_hiwater_vm(mm);
L
Linus Torvalds 已提交
2314
	do {
2315 2316
		long nrpages = vma_pages(vma);

2317 2318
		if (vma->vm_flags & VM_ACCOUNT)
			nr_accounted += nrpages;
2319
		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2320
		vma = remove_vma(vma);
2321
	} while (vma);
2322
	vm_unacct_memory(nr_accounted);
L
Linus Torvalds 已提交
2323 2324 2325 2326 2327 2328
	validate_mm(mm);
}

/*
 * Get rid of page table information in the indicated region.
 *
2329
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
2330 2331
 */
static void unmap_region(struct mm_struct *mm,
2332 2333
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end)
L
Linus Torvalds 已提交
2334
{
2335
	struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
P
Peter Zijlstra 已提交
2336
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
2337 2338

	lru_add_drain();
2339
	tlb_gather_mmu(&tlb, mm, start, end);
2340
	update_hiwater_rss(mm);
2341
	unmap_vmas(&tlb, vma, start, end);
P
Peter Zijlstra 已提交
2342
	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2343
				 next ? next->vm_start : USER_PGTABLES_CEILING);
P
Peter Zijlstra 已提交
2344
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358
}

/*
 * 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;

	insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2359
	vma->vm_prev = NULL;
L
Linus Torvalds 已提交
2360
	do {
2361
		vma_rb_erase(vma, &mm->mm_rb);
L
Linus Torvalds 已提交
2362 2363 2364 2365 2366
		mm->map_count--;
		tail_vma = vma;
		vma = vma->vm_next;
	} while (vma && vma->vm_start < end);
	*insertion_point = vma;
2367
	if (vma) {
2368
		vma->vm_prev = prev;
2369 2370 2371
		vma_gap_update(vma);
	} else
		mm->highest_vm_end = prev ? prev->vm_end : 0;
L
Linus Torvalds 已提交
2372 2373 2374 2375 2376
	tail_vma->vm_next = NULL;
	mm->mmap_cache = NULL;		/* Kill the cache. */
}

/*
2377 2378
 * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
 * munmap path where it doesn't make sense to fail.
L
Linus Torvalds 已提交
2379
 */
2380
static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
L
Linus Torvalds 已提交
2381 2382 2383
	      unsigned long addr, int new_below)
{
	struct vm_area_struct *new;
2384
	int err = -ENOMEM;
L
Linus Torvalds 已提交
2385

2386 2387
	if (is_vm_hugetlb_page(vma) && (addr &
					~(huge_page_mask(hstate_vma(vma)))))
L
Linus Torvalds 已提交
2388 2389
		return -EINVAL;

2390
	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2391
	if (!new)
2392
		goto out_err;
L
Linus Torvalds 已提交
2393 2394 2395 2396

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

2397 2398
	INIT_LIST_HEAD(&new->anon_vma_chain);

L
Linus Torvalds 已提交
2399 2400 2401 2402 2403 2404 2405
	if (new_below)
		new->vm_end = addr;
	else {
		new->vm_start = addr;
		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
	}

2406 2407
	err = vma_dup_policy(vma, new);
	if (err)
2408
		goto out_free_vma;
L
Linus Torvalds 已提交
2409

2410 2411 2412
	if (anon_vma_clone(new, vma))
		goto out_free_mpol;

2413
	if (new->vm_file)
L
Linus Torvalds 已提交
2414 2415 2416 2417 2418 2419
		get_file(new->vm_file);

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

	if (new_below)
2420
		err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
L
Linus Torvalds 已提交
2421 2422
			((addr - new->vm_start) >> PAGE_SHIFT), new);
	else
2423
		err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
L
Linus Torvalds 已提交
2424

2425 2426 2427 2428 2429
	/* Success. */
	if (!err)
		return 0;

	/* Clean everything up if vma_adjust failed. */
2430 2431
	if (new->vm_ops && new->vm_ops->close)
		new->vm_ops->close(new);
2432
	if (new->vm_file)
2433
		fput(new->vm_file);
2434
	unlink_anon_vmas(new);
2435
 out_free_mpol:
2436
	mpol_put(vma_policy(new));
2437 2438 2439 2440
 out_free_vma:
	kmem_cache_free(vm_area_cachep, new);
 out_err:
	return err;
L
Linus Torvalds 已提交
2441 2442
}

2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455
/*
 * Split a vma into two pieces at address 'addr', a new vma is allocated
 * either for the first part or the tail.
 */
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
	      unsigned long addr, int new_below)
{
	if (mm->map_count >= sysctl_max_map_count)
		return -ENOMEM;

	return __split_vma(mm, vma, addr, new_below);
}

L
Linus Torvalds 已提交
2456 2457 2458 2459 2460 2461 2462 2463
/* 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;
2464
	struct vm_area_struct *vma, *prev, *last;
L
Linus Torvalds 已提交
2465 2466 2467 2468 2469 2470 2471 2472

	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 */
2473
	vma = find_vma(mm, start);
2474
	if (!vma)
L
Linus Torvalds 已提交
2475
		return 0;
2476
	prev = vma->vm_prev;
2477
	/* we have  start < vma->vm_end  */
L
Linus Torvalds 已提交
2478 2479 2480

	/* if it doesn't overlap, we have nothing.. */
	end = start + len;
2481
	if (vma->vm_start >= end)
L
Linus Torvalds 已提交
2482 2483 2484 2485 2486 2487 2488 2489 2490
		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.
	 */
2491
	if (start > vma->vm_start) {
2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502
		int error;

		/*
		 * Make sure that map_count on return from munmap() will
		 * not exceed its limit; but let map_count go just above
		 * its limit temporarily, to help free resources as expected.
		 */
		if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
			return -ENOMEM;

		error = __split_vma(mm, vma, start, 0);
L
Linus Torvalds 已提交
2503 2504
		if (error)
			return error;
2505
		prev = vma;
L
Linus Torvalds 已提交
2506 2507 2508 2509 2510
	}

	/* Does it split the last one? */
	last = find_vma(mm, end);
	if (last && end > last->vm_start) {
2511
		int error = __split_vma(mm, last, end, 1);
L
Linus Torvalds 已提交
2512 2513 2514
		if (error)
			return error;
	}
2515
	vma = prev? prev->vm_next: mm->mmap;
L
Linus Torvalds 已提交
2516

2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530
	/*
	 * 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
2531 2532 2533
	/*
	 * Remove the vma's, and unmap the actual pages
	 */
2534 2535
	detach_vmas_to_be_unmapped(mm, vma, prev, end);
	unmap_region(mm, vma, prev, start, end);
L
Linus Torvalds 已提交
2536 2537

	/* Fix up all other VM information */
2538
	remove_vma_list(mm, vma);
L
Linus Torvalds 已提交
2539 2540 2541 2542

	return 0;
}

A
Al Viro 已提交
2543
int vm_munmap(unsigned long start, size_t len)
L
Linus Torvalds 已提交
2544 2545
{
	int ret;
A
Al Viro 已提交
2546
	struct mm_struct *mm = current->mm;
L
Linus Torvalds 已提交
2547 2548

	down_write(&mm->mmap_sem);
2549
	ret = do_munmap(mm, start, len);
L
Linus Torvalds 已提交
2550 2551 2552
	up_write(&mm->mmap_sem);
	return ret;
}
2553 2554 2555 2556 2557
EXPORT_SYMBOL(vm_munmap);

SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
{
	profile_munmap(addr);
A
Al Viro 已提交
2558
	return vm_munmap(addr, len);
2559
}
L
Linus Torvalds 已提交
2560 2561 2562

static inline void verify_mm_writelocked(struct mm_struct *mm)
{
2563
#ifdef CONFIG_DEBUG_VM
L
Linus Torvalds 已提交
2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575
	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.
 */
2576
static unsigned long do_brk(unsigned long addr, unsigned long len)
L
Linus Torvalds 已提交
2577 2578 2579 2580 2581 2582
{
	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;
2583
	int error;
L
Linus Torvalds 已提交
2584 2585 2586 2587 2588

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

2589 2590
	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

A
Al Viro 已提交
2591 2592
	error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
	if (error & ~PAGE_MASK)
2593 2594
		return error;

L
Linus Torvalds 已提交
2595 2596 2597 2598 2599
	/*
	 * mlock MCL_FUTURE?
	 */
	if (mm->def_flags & VM_LOCKED) {
		unsigned long locked, lock_limit;
2600 2601
		locked = len >> PAGE_SHIFT;
		locked += mm->locked_vm;
J
Jiri Slaby 已提交
2602
		lock_limit = rlimit(RLIMIT_MEMLOCK);
2603
		lock_limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617
		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:
2618
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
L
Linus Torvalds 已提交
2619 2620 2621 2622 2623 2624
		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
2625
	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2626 2627 2628 2629 2630
		return -ENOMEM;

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

2631
	if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2632 2633 2634
		return -ENOMEM;

	/* Can we just expand an old private anonymous mapping? */
2635 2636 2637
	vma = vma_merge(mm, prev, addr, addr + len, flags,
					NULL, NULL, pgoff, NULL);
	if (vma)
L
Linus Torvalds 已提交
2638 2639 2640 2641 2642
		goto out;

	/*
	 * create a vma struct for an anonymous mapping
	 */
P
Pekka Enberg 已提交
2643
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2644 2645 2646 2647 2648
	if (!vma) {
		vm_unacct_memory(len >> PAGE_SHIFT);
		return -ENOMEM;
	}

2649
	INIT_LIST_HEAD(&vma->anon_vma_chain);
L
Linus Torvalds 已提交
2650 2651 2652 2653 2654
	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;
	vma->vm_pgoff = pgoff;
	vma->vm_flags = flags;
2655
	vma->vm_page_prot = vm_get_page_prot(flags);
L
Linus Torvalds 已提交
2656 2657
	vma_link(mm, vma, prev, rb_link, rb_parent);
out:
2658
	perf_event_mmap(vma);
L
Linus Torvalds 已提交
2659
	mm->total_vm += len >> PAGE_SHIFT;
2660 2661
	if (flags & VM_LOCKED)
		mm->locked_vm += (len >> PAGE_SHIFT);
L
Linus Torvalds 已提交
2662 2663 2664
	return addr;
}

2665 2666 2667 2668
unsigned long vm_brk(unsigned long addr, unsigned long len)
{
	struct mm_struct *mm = current->mm;
	unsigned long ret;
2669
	bool populate;
2670 2671 2672

	down_write(&mm->mmap_sem);
	ret = do_brk(addr, len);
2673
	populate = ((mm->def_flags & VM_LOCKED) != 0);
2674
	up_write(&mm->mmap_sem);
2675 2676
	if (populate)
		mm_populate(addr, len);
2677 2678 2679
	return ret;
}
EXPORT_SYMBOL(vm_brk);
L
Linus Torvalds 已提交
2680 2681 2682 2683

/* Release all mmaps. */
void exit_mmap(struct mm_struct *mm)
{
P
Peter Zijlstra 已提交
2684
	struct mmu_gather tlb;
2685
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2686 2687
	unsigned long nr_accounted = 0;

2688
	/* mm's last user has gone, and its about to be pulled down */
A
Andrea Arcangeli 已提交
2689
	mmu_notifier_release(mm);
2690

2691 2692 2693 2694 2695 2696 2697 2698
	if (mm->locked_vm) {
		vma = mm->mmap;
		while (vma) {
			if (vma->vm_flags & VM_LOCKED)
				munlock_vma_pages_all(vma);
			vma = vma->vm_next;
		}
	}
2699 2700 2701

	arch_exit_mmap(mm);

2702
	vma = mm->mmap;
2703 2704 2705
	if (!vma)	/* Can happen if dup_mmap() received an OOM */
		return;

L
Linus Torvalds 已提交
2706 2707
	lru_add_drain();
	flush_cache_mm(mm);
2708
	tlb_gather_mmu(&tlb, mm, 0, -1);
2709
	/* update_hiwater_rss(mm) here? but nobody should be looking */
2710
	/* Use -1 here to ensure all VMAs in the mm are unmapped */
2711
	unmap_vmas(&tlb, vma, 0, -1);
H
Hugh Dickins 已提交
2712

2713
	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2714
	tlb_finish_mmu(&tlb, 0, -1);
L
Linus Torvalds 已提交
2715 2716

	/*
2717 2718
	 * Walk the list again, actually closing and freeing it,
	 * with preemption enabled, without holding any MM locks.
L
Linus Torvalds 已提交
2719
	 */
2720 2721 2722
	while (vma) {
		if (vma->vm_flags & VM_ACCOUNT)
			nr_accounted += vma_pages(vma);
2723
		vma = remove_vma(vma);
2724 2725
	}
	vm_unacct_memory(nr_accounted);
2726

2727
	WARN_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
L
Linus Torvalds 已提交
2728 2729 2730 2731
}

/* Insert vm structure into process list sorted by address
 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2732
 * then i_mmap_mutex is taken here.
L
Linus Torvalds 已提交
2733
 */
2734
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
2735
{
2736 2737
	struct vm_area_struct *prev;
	struct rb_node **rb_link, *rb_parent;
L
Linus Torvalds 已提交
2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754

	/*
	 * 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;
	}
2755 2756
	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
			   &prev, &rb_link, &rb_parent))
L
Linus Torvalds 已提交
2757
		return -ENOMEM;
2758
	if ((vma->vm_flags & VM_ACCOUNT) &&
2759
	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
2760
		return -ENOMEM;
2761

L
Linus Torvalds 已提交
2762 2763 2764 2765 2766 2767 2768 2769 2770
	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,
2771 2772
	unsigned long addr, unsigned long len, pgoff_t pgoff,
	bool *need_rmap_locks)
L
Linus Torvalds 已提交
2773 2774 2775 2776 2777 2778
{
	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;
2779
	bool faulted_in_anon_vma = true;
L
Linus Torvalds 已提交
2780 2781 2782 2783 2784

	/*
	 * If anonymous vma has not yet been faulted, update new pgoff
	 * to match new location, to increase its chance of merging.
	 */
2785
	if (unlikely(!vma->vm_file && !vma->anon_vma)) {
L
Linus Torvalds 已提交
2786
		pgoff = addr >> PAGE_SHIFT;
2787 2788
		faulted_in_anon_vma = false;
	}
L
Linus Torvalds 已提交
2789

2790 2791
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
		return NULL;	/* should never get here */
L
Linus Torvalds 已提交
2792 2793 2794 2795 2796 2797
	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
		 */
2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812
		if (unlikely(vma_start >= new_vma->vm_start &&
			     vma_start < new_vma->vm_end)) {
			/*
			 * The only way we can get a vma_merge with
			 * self during an mremap is if the vma hasn't
			 * been faulted in yet and we were allowed to
			 * reset the dst vma->vm_pgoff to the
			 * destination address of the mremap to allow
			 * the merge to happen. mremap must change the
			 * vm_pgoff linearity between src and dst vmas
			 * (in turn preventing a vma_merge) to be
			 * safe. It is only safe to keep the vm_pgoff
			 * linear if there are no pages mapped yet.
			 */
			VM_BUG_ON(faulted_in_anon_vma);
2813
			*vmap = vma = new_vma;
2814
		}
2815
		*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
L
Linus Torvalds 已提交
2816
	} else {
2817
		new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2818 2819
		if (new_vma) {
			*new_vma = *vma;
2820 2821 2822
			new_vma->vm_start = addr;
			new_vma->vm_end = addr + len;
			new_vma->vm_pgoff = pgoff;
2823
			if (vma_dup_policy(vma, new_vma))
2824 2825 2826 2827
				goto out_free_vma;
			INIT_LIST_HEAD(&new_vma->anon_vma_chain);
			if (anon_vma_clone(new_vma, vma))
				goto out_free_mempol;
2828
			if (new_vma->vm_file)
L
Linus Torvalds 已提交
2829 2830 2831 2832
				get_file(new_vma->vm_file);
			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);
2833
			*need_rmap_locks = false;
L
Linus Torvalds 已提交
2834 2835 2836
		}
	}
	return new_vma;
2837 2838

 out_free_mempol:
2839
	mpol_put(vma_policy(new_vma));
2840 2841 2842
 out_free_vma:
	kmem_cache_free(vm_area_cachep, new_vma);
	return NULL;
L
Linus Torvalds 已提交
2843
}
A
akpm@osdl.org 已提交
2844 2845 2846 2847 2848 2849 2850 2851 2852 2853

/*
 * 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;

J
Jiri Slaby 已提交
2854
	lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
A
akpm@osdl.org 已提交
2855 2856 2857 2858 2859

	if (cur + npages > lim)
		return 0;
	return 1;
}
2860 2861


N
Nick Piggin 已提交
2862 2863
static int special_mapping_fault(struct vm_area_struct *vma,
				struct vm_fault *vmf)
2864
{
N
Nick Piggin 已提交
2865
	pgoff_t pgoff;
2866 2867
	struct page **pages;

N
Nick Piggin 已提交
2868 2869 2870 2871 2872 2873 2874
	/*
	 * 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;
2875

N
Nick Piggin 已提交
2876 2877
	for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
		pgoff--;
2878 2879 2880 2881

	if (*pages) {
		struct page *page = *pages;
		get_page(page);
N
Nick Piggin 已提交
2882 2883
		vmf->page = page;
		return 0;
2884 2885
	}

N
Nick Piggin 已提交
2886
	return VM_FAULT_SIGBUS;
2887 2888 2889 2890 2891 2892 2893 2894 2895
}

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

2896
static const struct vm_operations_struct special_mapping_vmops = {
2897
	.close = special_mapping_close,
N
Nick Piggin 已提交
2898
	.fault = special_mapping_fault,
2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913
};

/*
 * 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)
{
2914
	int ret;
2915 2916 2917 2918 2919 2920
	struct vm_area_struct *vma;

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

2921
	INIT_LIST_HEAD(&vma->anon_vma_chain);
2922 2923 2924 2925
	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;

2926
	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2927
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2928 2929 2930 2931

	vma->vm_ops = &special_mapping_vmops;
	vma->vm_private_data = pages;

2932 2933 2934
	ret = insert_vm_struct(mm, vma);
	if (ret)
		goto out;
2935 2936 2937

	mm->total_vm += len >> PAGE_SHIFT;

2938
	perf_event_mmap(vma);
2939

2940
	return 0;
2941 2942 2943 2944

out:
	kmem_cache_free(vm_area_cachep, vma);
	return ret;
2945
}
2946 2947 2948

static DEFINE_MUTEX(mm_all_locks_mutex);

2949
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2950
{
2951
	if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
2952 2953 2954 2955
		/*
		 * The LSB of head.next can't change from under us
		 * because we hold the mm_all_locks_mutex.
		 */
2956
		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
2957 2958
		/*
		 * We can safely modify head.next after taking the
2959
		 * anon_vma->root->rwsem. If some other vma in this mm shares
2960 2961 2962 2963
		 * 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
2964
		 * anon_vma->root->rwsem.
2965 2966
		 */
		if (__test_and_set_bit(0, (unsigned long *)
2967
				       &anon_vma->root->rb_root.rb_node))
2968 2969 2970 2971
			BUG();
	}
}

2972
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985
{
	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();
2986
		mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007
	}
}

/*
 * 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.
 *
3008
 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3009 3010 3011 3012
 * 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
3013
 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024
 * 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;
3025
	struct anon_vma_chain *avc;
3026 3027 3028 3029 3030 3031 3032 3033 3034

	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)
3035
			vm_lock_mapping(mm, vma->vm_file->f_mapping);
3036
	}
3037 3038 3039 3040 3041

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (signal_pending(current))
			goto out_unlock;
		if (vma->anon_vma)
3042 3043
			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
				vm_lock_anon_vma(mm, avc->anon_vma);
3044
	}
3045

3046
	return 0;
3047 3048

out_unlock:
3049 3050
	mm_drop_all_locks(mm);
	return -EINTR;
3051 3052 3053 3054
}

static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
{
3055
	if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3056 3057 3058 3059 3060
		/*
		 * 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
3061
		 * the vma so the users using the anon_vma->rb_root will
3062 3063 3064 3065
		 * never see our bitflag.
		 *
		 * No need of atomic instructions here, head.next
		 * can't change from under us until we release the
3066
		 * anon_vma->root->rwsem.
3067 3068
		 */
		if (!__test_and_clear_bit(0, (unsigned long *)
3069
					  &anon_vma->root->rb_root.rb_node))
3070
			BUG();
3071
		anon_vma_unlock_write(anon_vma);
3072 3073 3074 3075 3076 3077 3078 3079 3080 3081
	}
}

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.
		 */
3082
		mutex_unlock(&mapping->i_mmap_mutex);
3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095
		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;
3096
	struct anon_vma_chain *avc;
3097 3098 3099 3100 3101 3102

	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)
3103 3104
			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
				vm_unlock_anon_vma(avc->anon_vma);
3105 3106 3107 3108 3109 3110
		if (vma->vm_file && vma->vm_file->f_mapping)
			vm_unlock_mapping(vma->vm_file->f_mapping);
	}

	mutex_unlock(&mm_all_locks_mutex);
}
3111 3112 3113 3114 3115 3116

/*
 * initialise the VMA slab
 */
void __init mmap_init(void)
{
3117 3118 3119 3120
	int ret;

	ret = percpu_counter_init(&vm_committed_as, 0);
	VM_BUG_ON(ret);
3121
}
3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132

/*
 * Initialise sysctl_user_reserve_kbytes.
 *
 * This is intended to prevent a user from starting a single memory hogging
 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
 * mode.
 *
 * The default value is min(3% of free memory, 128MB)
 * 128MB is enough to recover with sshd/login, bash, and top/kill.
 */
3133
static int init_user_reserve(void)
3134 3135 3136 3137 3138 3139 3140 3141 3142
{
	unsigned long free_kbytes;

	free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);

	sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
	return 0;
}
module_init(init_user_reserve)
3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153

/*
 * Initialise sysctl_admin_reserve_kbytes.
 *
 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
 * to log in and kill a memory hogging process.
 *
 * Systems with more than 256MB will reserve 8MB, enough to recover
 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
 * only reserve 3% of free pages by default.
 */
3154
static int init_admin_reserve(void)
3155 3156 3157 3158 3159 3160 3161 3162 3163
{
	unsigned long free_kbytes;

	free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);

	sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
	return 0;
}
module_init(init_admin_reserve)
3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233

/*
 * Reinititalise user and admin reserves if memory is added or removed.
 *
 * The default user reserve max is 128MB, and the default max for the
 * admin reserve is 8MB. These are usually, but not always, enough to
 * enable recovery from a memory hogging process using login/sshd, a shell,
 * and tools like top. It may make sense to increase or even disable the
 * reserve depending on the existence of swap or variations in the recovery
 * tools. So, the admin may have changed them.
 *
 * If memory is added and the reserves have been eliminated or increased above
 * the default max, then we'll trust the admin.
 *
 * If memory is removed and there isn't enough free memory, then we
 * need to reset the reserves.
 *
 * Otherwise keep the reserve set by the admin.
 */
static int reserve_mem_notifier(struct notifier_block *nb,
			     unsigned long action, void *data)
{
	unsigned long tmp, free_kbytes;

	switch (action) {
	case MEM_ONLINE:
		/* Default max is 128MB. Leave alone if modified by operator. */
		tmp = sysctl_user_reserve_kbytes;
		if (0 < tmp && tmp < (1UL << 17))
			init_user_reserve();

		/* Default max is 8MB.  Leave alone if modified by operator. */
		tmp = sysctl_admin_reserve_kbytes;
		if (0 < tmp && tmp < (1UL << 13))
			init_admin_reserve();

		break;
	case MEM_OFFLINE:
		free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);

		if (sysctl_user_reserve_kbytes > free_kbytes) {
			init_user_reserve();
			pr_info("vm.user_reserve_kbytes reset to %lu\n",
				sysctl_user_reserve_kbytes);
		}

		if (sysctl_admin_reserve_kbytes > free_kbytes) {
			init_admin_reserve();
			pr_info("vm.admin_reserve_kbytes reset to %lu\n",
				sysctl_admin_reserve_kbytes);
		}
		break;
	default:
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block reserve_mem_nb = {
	.notifier_call = reserve_mem_notifier,
};

static int __meminit init_reserve_notifier(void)
{
	if (register_hotmemory_notifier(&reserve_mem_nb))
		printk("Failed registering memory add/remove notifier for admin reserve");

	return 0;
}
module_init(init_reserve_notifier)