mmap.c 86.6 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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unsigned long sysctl_overcommit_kbytes __read_mostly;
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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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	}

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	allowed = vm_commit_limit();
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	/*
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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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	/*
	 * 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;
550
	return 0;
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}

553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580
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)
{
584 585 586 587 588 589 590 591 592 593 594 595 596 597 598
	/* 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);
600 601 602
	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
622
			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;

645
	if (mapping)
646
		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)
652
		mutex_unlock(&mapping->i_mmap_mutex);
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	mm->map_count++;
	validate_mm(mm);
}

/*
659
 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
660
 * 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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{
664
	struct vm_area_struct *prev;
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	struct rb_node **rb_link, *rb_parent;
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667 668 669
	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)
{
678
	struct vm_area_struct *next;
679

680 681
	vma_rb_erase(vma, &mm->mm_rb);
	prev->vm_next = next = vma->vm_next;
682 683
	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.
 */
695
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;
702
	struct rb_root *root = NULL;
703
	struct anon_vma *anon_vma = NULL;
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	struct file *file = vma->vm_file;
705
	bool start_changed = false, end_changed = false;
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	long adjust_next = 0;
	int remove_next = 0;

	if (next && !insert) {
710 711
		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;
719
			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;
727
			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);
736
			exporter = vma;
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			importer = next;
		}

740 741 742 743 744
		/*
		 * 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.
		 */
745 746
		if (exporter && exporter->anon_vma && !importer->anon_vma) {
			if (anon_vma_clone(importer, exporter))
747
				return -ENOMEM;
748
			importer->anon_vma = exporter->anon_vma;
749 750 751
		}
	}

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	if (file) {
		mapping = file->f_mapping;
754
		if (!(vma->vm_flags & VM_NONLINEAR)) {
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			root = &mapping->i_mmap;
756
			uprobe_munmap(vma, vma->vm_start, vma->vm_end);
757 758

			if (adjust_next)
759 760
				uprobe_munmap(next, next->vm_start,
							next->vm_end);
761 762
		}

763
		mutex_lock(&mapping->i_mmap_mutex);
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		if (insert) {
			/*
766
			 * 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);
		}
	}

775 776
	vma_adjust_trans_huge(vma, start, end, adjust_next);

777 778 779 780
	anon_vma = vma->anon_vma;
	if (!anon_vma && adjust_next)
		anon_vma = next->anon_vma;
	if (anon_vma) {
781 782
		VM_BUG_ON(adjust_next && next->anon_vma &&
			  anon_vma != next->anon_vma);
783
		anon_vma_lock_write(anon_vma);
784 785 786 787
		anon_vma_interval_tree_pre_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_pre_update_vma(next);
	}
788

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	if (root) {
		flush_dcache_mmap_lock(mapping);
791
		vma_interval_tree_remove(vma, root);
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		if (adjust_next)
793
			vma_interval_tree_remove(next, root);
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	}

796 797 798 799 800 801 802 803
	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)
812 813
			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);
832 833 834 835 836 837 838 839 840
	} 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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	}

843 844 845 846
	if (anon_vma) {
		anon_vma_interval_tree_post_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_post_update_vma(next);
847
		anon_vma_unlock_write(anon_vma);
848
	}
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	if (mapping)
850
		mutex_unlock(&mapping->i_mmap_mutex);
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852
	if (root) {
853
		uprobe_mmap(vma);
854 855

		if (adjust_next)
856
			uprobe_mmap(next);
857 858
	}

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	if (remove_next) {
M
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860
		if (file) {
861
			uprobe_munmap(next, next->vm_start, next->vm_end);
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			fput(file);
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		}
864 865
		if (next->anon_vma)
			anon_vma_merge(vma, next);
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866
		mm->map_count--;
867
		mpol_put(vma_policy(next));
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		kmem_cache_free(vm_area_cachep, next);
		/*
		 * In mprotect's case 6 (see comments on vma_merge),
		 * we must remove another next too. It would clutter
		 * up the code too much to do both in one go.
		 */
874 875
		next = vma->vm_next;
		if (remove_next == 2)
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			goto again;
877 878 879 880
		else if (next)
			vma_gap_update(next);
		else
			mm->highest_vm_end = end;
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	}
882
	if (insert && file)
883
		uprobe_mmap(insert);
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884 885

	validate_mm(mm);
886 887

	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)
{
897 898 899 900 901 902 903 904 905
	/*
	 * VM_SOFTDIRTY should not prevent from VMA merging, if we
	 * match the flags but dirty bit -- the caller should mark
	 * merged VMA as dirty. If dirty bit won't be excluded from
	 * comparison, we increase pressue on the memory system forcing
	 * the kernel to generate new VMAs when old one could be
	 * extended instead.
	 */
	if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
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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,
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					struct anon_vma *anon_vma2,
					struct vm_area_struct *vma)
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{
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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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}

/*
 * 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
944
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
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945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962
		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
963
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
L
Linus Torvalds 已提交
964
		pgoff_t vm_pglen;
965
		vm_pglen = vma_pages(vma);
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Linus Torvalds 已提交
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 1002 1003 1004 1005 1006 1007 1008
		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;
1009
	int err;
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1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040

	/*
	 * 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
1041
						      next->anon_vma, NULL)) {
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1042
							/* cases 1, 6 */
1043
			err = vma_adjust(prev, prev->vm_start,
L
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1044 1045
				next->vm_end, prev->vm_pgoff, NULL);
		} else					/* cases 2, 5, 7 */
1046
			err = vma_adjust(prev, prev->vm_start,
L
Linus Torvalds 已提交
1047
				end, prev->vm_pgoff, NULL);
1048 1049
		if (err)
			return NULL;
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Andrea Arcangeli 已提交
1050
		khugepaged_enter_vma_merge(prev);
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1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
		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 */
1062
			err = vma_adjust(prev, prev->vm_start,
L
Linus Torvalds 已提交
1063 1064
				addr, prev->vm_pgoff, NULL);
		else					/* cases 3, 8 */
1065
			err = vma_adjust(area, addr, next->vm_end,
L
Linus Torvalds 已提交
1066
				next->vm_pgoff - pglen, NULL);
1067 1068
		if (err)
			return NULL;
A
Andrea Arcangeli 已提交
1069
		khugepaged_enter_vma_merge(area);
L
Linus Torvalds 已提交
1070 1071 1072 1073 1074 1075
		return area;
	}

	return NULL;
}

1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093
/*
 * 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 &&
1094
		!((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
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 1124 1125 1126 1127 1128 1129 1130
		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
1131 1132 1133 1134 1135 1136 1137 1138 1139 1140
/*
 * 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)
{
1141
	struct anon_vma *anon_vma;
L
Linus Torvalds 已提交
1142 1143 1144 1145 1146 1147
	struct vm_area_struct *near;

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

1148 1149 1150
	anon_vma = reusable_anon_vma(near, vma, near);
	if (anon_vma)
		return anon_vma;
L
Linus Torvalds 已提交
1151
try_prev:
1152
	near = vma->vm_prev;
L
Linus Torvalds 已提交
1153 1154 1155
	if (!near)
		goto none;

1156 1157 1158
	anon_vma = reusable_anon_vma(near, near, vma);
	if (anon_vma)
		return anon_vma;
L
Linus Torvalds 已提交
1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171
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
1172
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
L
Linus Torvalds 已提交
1173 1174 1175 1176 1177
						struct file *file, long pages)
{
	const unsigned long stack_flags
		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);

1178 1179
	mm->total_vm += pages;

L
Linus Torvalds 已提交
1180 1181 1182 1183 1184 1185 1186 1187 1188
	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
1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201
/*
 * 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;
}

1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219
static inline int mlock_future_check(struct mm_struct *mm,
				     unsigned long flags,
				     unsigned long len)
{
	unsigned long locked, lock_limit;

	/*  mlock MCL_FUTURE? */
	if (flags & VM_LOCKED) {
		locked = len >> PAGE_SHIFT;
		locked += mm->locked_vm;
		lock_limit = rlimit(RLIMIT_MEMLOCK);
		lock_limit >>= PAGE_SHIFT;
		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
			return -EAGAIN;
	}
	return 0;
}

L
Linus Torvalds 已提交
1220
/*
1221
 * The caller must hold down_write(&current->mm->mmap_sem).
L
Linus Torvalds 已提交
1222 1223
 */

1224
unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
L
Linus Torvalds 已提交
1225
			unsigned long len, unsigned long prot,
1226
			unsigned long flags, unsigned long pgoff,
1227
			unsigned long *populate)
L
Linus Torvalds 已提交
1228 1229
{
	struct mm_struct * mm = current->mm;
1230
	vm_flags_t vm_flags;
L
Linus Torvalds 已提交
1231

1232
	*populate = 0;
1233

L
Linus Torvalds 已提交
1234 1235 1236 1237 1238 1239 1240
	/*
	 * 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))
1241
		if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
L
Linus Torvalds 已提交
1242 1243 1244 1245 1246
			prot |= PROT_EXEC;

	if (!len)
		return -EINVAL;

1247 1248 1249
	if (!(flags & MAP_FIXED))
		addr = round_hint_to_min(addr);

L
Linus Torvalds 已提交
1250 1251
	/* Careful about overflows.. */
	len = PAGE_ALIGN(len);
1252
	if (!len)
L
Linus Torvalds 已提交
1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276
		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
1277
	if (flags & MAP_LOCKED)
L
Linus Torvalds 已提交
1278 1279
		if (!can_do_mlock())
			return -EPERM;
1280

1281 1282
	if (mlock_future_check(mm, vm_flags, len))
		return -EAGAIN;
L
Linus Torvalds 已提交
1283 1284

	if (file) {
1285 1286
		struct inode *inode = file_inode(file);

L
Linus Torvalds 已提交
1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312
		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;
1313
			if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
L
Linus Torvalds 已提交
1314 1315 1316 1317 1318
				if (vm_flags & VM_EXEC)
					return -EPERM;
				vm_flags &= ~VM_MAYEXEC;
			}

A
Al Viro 已提交
1319
			if (!file->f_op->mmap)
L
Linus Torvalds 已提交
1320
				return -ENODEV;
1321 1322
			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
				return -EINVAL;
L
Linus Torvalds 已提交
1323 1324 1325 1326 1327 1328 1329 1330
			break;

		default:
			return -EINVAL;
		}
	} else {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
1331 1332
			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
				return -EINVAL;
1333 1334 1335 1336
			/*
			 * Ignore pgoff.
			 */
			pgoff = 0;
L
Linus Torvalds 已提交
1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349
			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;
		}
	}

1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364
	/*
	 * 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);
1365 1366 1367
	if (!IS_ERR_VALUE(addr) &&
	    ((vm_flags & VM_LOCKED) ||
	     (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1368
		*populate = len;
1369
	return addr;
M
Miklos Szeredi 已提交
1370
}
1371

H
Hugh Dickins 已提交
1372 1373 1374 1375 1376 1377 1378 1379
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
1380
		audit_mmap_fd(fd, flags);
H
Hugh Dickins 已提交
1381 1382 1383
		file = fget(fd);
		if (!file)
			goto out;
1384 1385
		if (is_file_hugepages(file))
			len = ALIGN(len, huge_page_size(hstate_file(file)));
1386 1387 1388
		retval = -EINVAL;
		if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
			goto out_fput;
H
Hugh Dickins 已提交
1389 1390
	} else if (flags & MAP_HUGETLB) {
		struct user_struct *user = NULL;
1391
		struct hstate *hs;
1392

1393
		hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1394 1395 1396 1397
		if (!hs)
			return -EINVAL;

		len = ALIGN(len, huge_page_size(hs));
H
Hugh Dickins 已提交
1398 1399 1400 1401 1402 1403
		/*
		 * 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
		 */
1404
		file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1405 1406 1407
				VM_NORESERVE,
				&user, HUGETLB_ANONHUGE_INODE,
				(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
H
Hugh Dickins 已提交
1408 1409 1410 1411 1412 1413
		if (IS_ERR(file))
			return PTR_ERR(file);
	}

	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);

A
Al Viro 已提交
1414
	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1415
out_fput:
H
Hugh Dickins 已提交
1416 1417 1418 1419 1420 1421
	if (file)
		fput(file);
out:
	return retval;
}

C
Christoph Hellwig 已提交
1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445
#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
1446 1447 1448 1449 1450 1451 1452 1453
/*
 * 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)
{
1454
	vm_flags_t vm_flags = vma->vm_flags;
A
Alexey Dobriyan 已提交
1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465

	/* 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) !=
1466
	    pgprot_val(vm_get_page_prot(vm_flags)))
A
Alexey Dobriyan 已提交
1467 1468 1469
		return 0;

	/* Specialty mapping? */
1470
	if (vm_flags & VM_PFNMAP)
A
Alexey Dobriyan 已提交
1471 1472 1473 1474 1475 1476 1477
		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);
}

1478 1479
/*
 * We account for memory if it's a private writeable mapping,
1480
 * not hugepages and VM_NORESERVE wasn't set.
1481
 */
1482
static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1483
{
1484 1485 1486 1487 1488 1489 1490
	/*
	 * 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;

1491 1492 1493
	return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
}

M
Miklos Szeredi 已提交
1494
unsigned long mmap_region(struct file *file, unsigned long addr,
1495
		unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
M
Miklos Szeredi 已提交
1496 1497 1498 1499 1500 1501 1502
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma, *prev;
	int error;
	struct rb_node **rb_link, *rb_parent;
	unsigned long charged = 0;

1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519
	/* 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
1520 1521 1522
	/* Clear old maps */
	error = -ENOMEM;
munmap_back:
1523
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
L
Linus Torvalds 已提交
1524 1525 1526 1527 1528
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

1529 1530 1531
	/*
	 * Private writable mapping: check memory availability
	 */
1532
	if (accountable_mapping(file, vm_flags)) {
1533
		charged = len >> PAGE_SHIFT;
1534
		if (security_vm_enough_memory_mm(mm, charged))
1535 1536
			return -ENOMEM;
		vm_flags |= VM_ACCOUNT;
L
Linus Torvalds 已提交
1537 1538 1539
	}

	/*
1540
	 * Can we just expand an old mapping?
L
Linus Torvalds 已提交
1541
	 */
1542 1543 1544
	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
	if (vma)
		goto out;
L
Linus Torvalds 已提交
1545 1546 1547 1548 1549 1550

	/*
	 * 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
1551
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
1552 1553 1554 1555 1556 1557 1558 1559 1560
	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;
1561
	vma->vm_page_prot = vm_get_page_prot(vm_flags);
L
Linus Torvalds 已提交
1562
	vma->vm_pgoff = pgoff;
1563
	INIT_LIST_HEAD(&vma->anon_vma_chain);
L
Linus Torvalds 已提交
1564 1565 1566 1567 1568 1569 1570

	if (file) {
		if (vm_flags & VM_DENYWRITE) {
			error = deny_write_access(file);
			if (error)
				goto free_vma;
		}
A
Al Viro 已提交
1571
		vma->vm_file = get_file(file);
L
Linus Torvalds 已提交
1572 1573 1574
		error = file->f_op->mmap(file, vma);
		if (error)
			goto unmap_and_free_vma;
1575 1576 1577 1578 1579

		/* Can addr have changed??
		 *
		 * Answer: Yes, several device drivers can do it in their
		 *         f_op->mmap method. -DaveM
1580 1581
		 * Bug: If addr is changed, prev, rb_link, rb_parent should
		 *      be updated for vma_link()
1582
		 */
1583 1584
		WARN_ON_ONCE(addr != vma->vm_start);

1585 1586
		addr = vma->vm_start;
		vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
1587 1588 1589 1590 1591 1592
	} else if (vm_flags & VM_SHARED) {
		error = shmem_zero_setup(vma);
		if (error)
			goto free_vma;
	}

1593 1594 1595 1596 1597 1598 1599 1600 1601 1602
	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.
		 */
1603
		vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1604 1605 1606
		if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
			vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	}
1607

1608
	vma_link(mm, vma, prev, rb_link, rb_parent);
1609
	/* Once vma denies write, undo our temporary denial count */
1610 1611 1612
	if (vm_flags & VM_DENYWRITE)
		allow_write_access(file);
	file = vma->vm_file;
1613
out:
1614
	perf_event_mmap(vma);
1615

1616
	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
L
Linus Torvalds 已提交
1617
	if (vm_flags & VM_LOCKED) {
1618 1619
		if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
					vma == get_gate_vma(current->mm)))
1620
			mm->locked_vm += (len >> PAGE_SHIFT);
1621 1622 1623
		else
			vma->vm_flags &= ~VM_LOCKED;
	}
1624

1625 1626
	if (file)
		uprobe_mmap(vma);
1627

1628 1629 1630 1631 1632 1633 1634 1635 1636
	/*
	 * New (or expanded) vma always get soft dirty status.
	 * Otherwise user-space soft-dirty page tracker won't
	 * be able to distinguish situation when vma area unmapped,
	 * then new mapped in-place (which must be aimed as
	 * a completely new data area).
	 */
	vma->vm_flags |= VM_SOFTDIRTY;

L
Linus Torvalds 已提交
1637 1638 1639
	return addr;

unmap_and_free_vma:
1640 1641
	if (vm_flags & VM_DENYWRITE)
		allow_write_access(file);
L
Linus Torvalds 已提交
1642 1643 1644 1645
	vma->vm_file = NULL;
	fput(file);

	/* Undo any partial mapping done by a device driver. */
1646 1647
	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
	charged = 0;
L
Linus Torvalds 已提交
1648 1649 1650 1651 1652 1653 1654 1655
free_vma:
	kmem_cache_free(vm_area_cachep, vma);
unacct_error:
	if (charged)
		vm_unacct_memory(charged);
	return error;
}

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 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855
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
1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873
/* 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;
1874
	struct vm_unmapped_area_info info;
L
Linus Torvalds 已提交
1875

1876
	if (len > TASK_SIZE - mmap_min_addr)
L
Linus Torvalds 已提交
1877 1878
		return -ENOMEM;

1879 1880 1881
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1882 1883 1884
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
1885
		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
L
Linus Torvalds 已提交
1886 1887 1888 1889
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}

1890 1891
	info.flags = 0;
	info.length = len;
1892
	info.low_limit = mm->mmap_base;
1893 1894 1895
	info.high_limit = TASK_SIZE;
	info.align_mask = 0;
	return vm_unmapped_area(&info);
L
Linus Torvalds 已提交
1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910
}
#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;
1911 1912
	unsigned long addr = addr0;
	struct vm_unmapped_area_info info;
L
Linus Torvalds 已提交
1913 1914

	/* requested length too big for entire address space */
1915
	if (len > TASK_SIZE - mmap_min_addr)
L
Linus Torvalds 已提交
1916 1917
		return -ENOMEM;

1918 1919 1920
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1921 1922 1923 1924
	/* requesting a specific address */
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
1925
		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
L
Linus Torvalds 已提交
1926 1927 1928 1929
				(!vma || addr + len <= vma->vm_start))
			return addr;
	}

1930 1931
	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
1932
	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1933 1934 1935
	info.high_limit = mm->mmap_base;
	info.align_mask = 0;
	addr = vm_unmapped_area(&info);
1936

L
Linus Torvalds 已提交
1937 1938 1939 1940 1941 1942
	/*
	 * 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.
	 */
1943 1944 1945 1946 1947 1948 1949
	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
1950 1951 1952 1953 1954 1955 1956 1957 1958

	return addr;
}
#endif

unsigned long
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
1959 1960 1961
	unsigned long (*get_area)(struct file *, unsigned long,
				  unsigned long, unsigned long, unsigned long);

1962 1963 1964 1965 1966 1967 1968 1969
	unsigned long error = arch_mmap_check(addr, len, flags);
	if (error)
		return error;

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

1970
	get_area = current->mm->get_unmapped_area;
A
Al Viro 已提交
1971
	if (file && file->f_op->get_unmapped_area)
1972 1973 1974 1975
		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
1976

1977 1978 1979 1980
	if (addr > TASK_SIZE - len)
		return -ENOMEM;
	if (addr & ~PAGE_MASK)
		return -EINVAL;
1981

1982 1983 1984
	addr = arch_rebalance_pgtables(addr, len);
	error = security_mmap_addr(addr);
	return error ? error : addr;
L
Linus Torvalds 已提交
1985 1986 1987 1988 1989
}

EXPORT_SYMBOL(get_unmapped_area);

/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
Z
ZhenwenXu 已提交
1990
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1991 1992 1993
{
	struct vm_area_struct *vma = NULL;

1994 1995
	/* Check the cache first. */
	/* (Cache hit rate is typically around 35%.) */
1996
	vma = ACCESS_ONCE(mm->mmap_cache);
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
	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
2016
		}
2017 2018
		if (vma)
			mm->mmap_cache = vma;
L
Linus Torvalds 已提交
2019 2020 2021 2022 2023 2024
	}
	return vma;
}

EXPORT_SYMBOL(find_vma);

K
KOSAKI Motohiro 已提交
2025 2026 2027
/*
 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
 */
L
Linus Torvalds 已提交
2028 2029 2030 2031
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
2032
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2033

K
KOSAKI Motohiro 已提交
2034
	vma = find_vma(mm, addr);
M
Mikulas Patocka 已提交
2035 2036 2037 2038 2039 2040 2041 2042 2043 2044
	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
2045
	return vma;
L
Linus Torvalds 已提交
2046 2047 2048 2049 2050 2051 2052
}

/*
 * 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
2053
static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
L
Linus Torvalds 已提交
2054 2055 2056
{
	struct mm_struct *mm = vma->vm_mm;
	struct rlimit *rlim = current->signal->rlim;
2057
	unsigned long new_start;
L
Linus Torvalds 已提交
2058 2059

	/* address space limit tests */
A
akpm@osdl.org 已提交
2060
	if (!may_expand_vm(mm, grow))
L
Linus Torvalds 已提交
2061 2062 2063
		return -ENOMEM;

	/* Stack limit test */
J
Jiri Slaby 已提交
2064
	if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
L
Linus Torvalds 已提交
2065 2066 2067 2068 2069 2070 2071
		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
2072 2073
		limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
		limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
2074 2075 2076 2077
		if (locked > limit && !capable(CAP_IPC_LOCK))
			return -ENOMEM;
	}

2078 2079 2080 2081 2082 2083
	/* 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
2084 2085 2086 2087
	/*
	 * Overcommit..  This must be the final test, as it will
	 * update security statistics.
	 */
2088
	if (security_vm_enough_memory_mm(mm, grow))
L
Linus Torvalds 已提交
2089 2090 2091 2092 2093
		return -ENOMEM;

	/* Ok, everything looks good - let it rip */
	if (vma->vm_flags & VM_LOCKED)
		mm->locked_vm += grow;
2094
	vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
L
Linus Torvalds 已提交
2095 2096 2097
	return 0;
}

H
Hugh Dickins 已提交
2098
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
L
Linus Torvalds 已提交
2099
/*
H
Hugh Dickins 已提交
2100 2101
 * 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
2102
 */
H
Hugh Dickins 已提交
2103
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
L
Linus Torvalds 已提交
2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115
{
	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;
2116
	vma_lock_anon_vma(vma);
L
Linus Torvalds 已提交
2117 2118 2119 2120 2121

	/*
	 * 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.
2122
	 * Also guard against wrapping around to address 0.
L
Linus Torvalds 已提交
2123
	 */
2124 2125 2126
	if (address < PAGE_ALIGN(address+4))
		address = PAGE_ALIGN(address+4);
	else {
2127
		vma_unlock_anon_vma(vma);
2128 2129
		return -ENOMEM;
	}
L
Linus Torvalds 已提交
2130 2131 2132 2133 2134 2135 2136 2137 2138
	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;

2139 2140 2141 2142
		error = -ENOMEM;
		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
			error = acct_stack_growth(vma, size, grow);
			if (!error) {
2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154
				/*
				 * 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);
2155
				anon_vma_interval_tree_pre_update_vma(vma);
2156
				vma->vm_end = address;
2157
				anon_vma_interval_tree_post_update_vma(vma);
2158 2159 2160 2161
				if (vma->vm_next)
					vma_gap_update(vma->vm_next);
				else
					vma->vm_mm->highest_vm_end = address;
2162 2163
				spin_unlock(&vma->vm_mm->page_table_lock);

2164 2165
				perf_event_mmap(vma);
			}
2166
		}
L
Linus Torvalds 已提交
2167
	}
2168
	vma_unlock_anon_vma(vma);
A
Andrea Arcangeli 已提交
2169
	khugepaged_enter_vma_merge(vma);
2170
	validate_mm(vma->vm_mm);
L
Linus Torvalds 已提交
2171 2172
	return error;
}
H
Hugh Dickins 已提交
2173 2174
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */

L
Linus Torvalds 已提交
2175 2176 2177
/*
 * vma is the first one with address < vma->vm_start.  Have to extend vma.
 */
2178
int expand_downwards(struct vm_area_struct *vma,
2179
				   unsigned long address)
L
Linus Torvalds 已提交
2180 2181 2182 2183 2184 2185 2186 2187 2188
{
	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;
2189 2190

	address &= PAGE_MASK;
2191
	error = security_mmap_addr(address);
2192 2193 2194
	if (error)
		return error;

2195
	vma_lock_anon_vma(vma);
L
Linus Torvalds 已提交
2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209

	/*
	 * 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;

2210 2211 2212 2213
		error = -ENOMEM;
		if (grow <= vma->vm_pgoff) {
			error = acct_stack_growth(vma, size, grow);
			if (!error) {
2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225
				/*
				 * 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);
2226
				anon_vma_interval_tree_pre_update_vma(vma);
2227 2228
				vma->vm_start = address;
				vma->vm_pgoff -= grow;
2229
				anon_vma_interval_tree_post_update_vma(vma);
2230
				vma_gap_update(vma);
2231 2232
				spin_unlock(&vma->vm_mm->page_table_lock);

2233 2234
				perf_event_mmap(vma);
			}
L
Linus Torvalds 已提交
2235 2236
		}
	}
2237
	vma_unlock_anon_vma(vma);
A
Andrea Arcangeli 已提交
2238
	khugepaged_enter_vma_merge(vma);
2239
	validate_mm(vma->vm_mm);
L
Linus Torvalds 已提交
2240 2241 2242
	return error;
}

2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253
/*
 * 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.
 */
2254 2255 2256
#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
2257 2258 2259 2260 2261 2262 2263 2264
	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;
	}
2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276
	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;
2277
	if (!prev || expand_stack(prev, addr))
2278
		return NULL;
2279 2280
	if (prev->vm_flags & VM_LOCKED)
		__mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);
2281 2282 2283 2284 2285
	return prev;
}
#else
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
2286 2287 2288 2289 2290 2291 2292 2293
	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;
	}
2294 2295 2296
	return expand_downwards(vma, address);
}

L
Linus Torvalds 已提交
2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313
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;
2314 2315
	if (vma->vm_flags & VM_LOCKED)
		__mlock_vma_pages_range(vma, addr, start, NULL);
L
Linus Torvalds 已提交
2316 2317 2318 2319 2320
	return vma;
}
#endif

/*
2321
 * Ok - we have the memory areas we should free on the vma list,
L
Linus Torvalds 已提交
2322
 * so release them, and do the vma updates.
2323 2324
 *
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
2325
 */
2326
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
2327
{
2328 2329
	unsigned long nr_accounted = 0;

2330 2331
	/* Update high watermark before we lower total_vm */
	update_hiwater_vm(mm);
L
Linus Torvalds 已提交
2332
	do {
2333 2334
		long nrpages = vma_pages(vma);

2335 2336
		if (vma->vm_flags & VM_ACCOUNT)
			nr_accounted += nrpages;
2337
		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2338
		vma = remove_vma(vma);
2339
	} while (vma);
2340
	vm_unacct_memory(nr_accounted);
L
Linus Torvalds 已提交
2341 2342 2343 2344 2345 2346
	validate_mm(mm);
}

/*
 * Get rid of page table information in the indicated region.
 *
2347
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
2348 2349
 */
static void unmap_region(struct mm_struct *mm,
2350 2351
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end)
L
Linus Torvalds 已提交
2352
{
2353
	struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
P
Peter Zijlstra 已提交
2354
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
2355 2356

	lru_add_drain();
2357
	tlb_gather_mmu(&tlb, mm, start, end);
2358
	update_hiwater_rss(mm);
2359
	unmap_vmas(&tlb, vma, start, end);
P
Peter Zijlstra 已提交
2360
	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2361
				 next ? next->vm_start : USER_PGTABLES_CEILING);
P
Peter Zijlstra 已提交
2362
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376
}

/*
 * 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);
2377
	vma->vm_prev = NULL;
L
Linus Torvalds 已提交
2378
	do {
2379
		vma_rb_erase(vma, &mm->mm_rb);
L
Linus Torvalds 已提交
2380 2381 2382 2383 2384
		mm->map_count--;
		tail_vma = vma;
		vma = vma->vm_next;
	} while (vma && vma->vm_start < end);
	*insertion_point = vma;
2385
	if (vma) {
2386
		vma->vm_prev = prev;
2387 2388 2389
		vma_gap_update(vma);
	} else
		mm->highest_vm_end = prev ? prev->vm_end : 0;
L
Linus Torvalds 已提交
2390 2391 2392 2393 2394
	tail_vma->vm_next = NULL;
	mm->mmap_cache = NULL;		/* Kill the cache. */
}

/*
2395 2396
 * __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
2397
 */
2398
static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
L
Linus Torvalds 已提交
2399 2400 2401
	      unsigned long addr, int new_below)
{
	struct vm_area_struct *new;
2402
	int err = -ENOMEM;
L
Linus Torvalds 已提交
2403

2404 2405
	if (is_vm_hugetlb_page(vma) && (addr &
					~(huge_page_mask(hstate_vma(vma)))))
L
Linus Torvalds 已提交
2406 2407
		return -EINVAL;

2408
	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2409
	if (!new)
2410
		goto out_err;
L
Linus Torvalds 已提交
2411 2412 2413 2414

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

2415 2416
	INIT_LIST_HEAD(&new->anon_vma_chain);

L
Linus Torvalds 已提交
2417 2418 2419 2420 2421 2422 2423
	if (new_below)
		new->vm_end = addr;
	else {
		new->vm_start = addr;
		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
	}

2424 2425
	err = vma_dup_policy(vma, new);
	if (err)
2426
		goto out_free_vma;
L
Linus Torvalds 已提交
2427

2428 2429 2430
	if (anon_vma_clone(new, vma))
		goto out_free_mpol;

2431
	if (new->vm_file)
L
Linus Torvalds 已提交
2432 2433 2434 2435 2436 2437
		get_file(new->vm_file);

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

	if (new_below)
2438
		err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
L
Linus Torvalds 已提交
2439 2440
			((addr - new->vm_start) >> PAGE_SHIFT), new);
	else
2441
		err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
L
Linus Torvalds 已提交
2442

2443 2444 2445 2446 2447
	/* Success. */
	if (!err)
		return 0;

	/* Clean everything up if vma_adjust failed. */
2448 2449
	if (new->vm_ops && new->vm_ops->close)
		new->vm_ops->close(new);
2450
	if (new->vm_file)
2451
		fput(new->vm_file);
2452
	unlink_anon_vmas(new);
2453
 out_free_mpol:
2454
	mpol_put(vma_policy(new));
2455 2456 2457 2458
 out_free_vma:
	kmem_cache_free(vm_area_cachep, new);
 out_err:
	return err;
L
Linus Torvalds 已提交
2459 2460
}

2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473
/*
 * 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
2474 2475 2476 2477 2478 2479 2480 2481
/* 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;
2482
	struct vm_area_struct *vma, *prev, *last;
L
Linus Torvalds 已提交
2483 2484 2485 2486 2487 2488 2489 2490

	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 */
2491
	vma = find_vma(mm, start);
2492
	if (!vma)
L
Linus Torvalds 已提交
2493
		return 0;
2494
	prev = vma->vm_prev;
2495
	/* we have  start < vma->vm_end  */
L
Linus Torvalds 已提交
2496 2497 2498

	/* if it doesn't overlap, we have nothing.. */
	end = start + len;
2499
	if (vma->vm_start >= end)
L
Linus Torvalds 已提交
2500 2501 2502 2503 2504 2505 2506 2507 2508
		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.
	 */
2509
	if (start > vma->vm_start) {
2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520
		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
2521 2522
		if (error)
			return error;
2523
		prev = vma;
L
Linus Torvalds 已提交
2524 2525 2526 2527 2528
	}

	/* Does it split the last one? */
	last = find_vma(mm, end);
	if (last && end > last->vm_start) {
2529
		int error = __split_vma(mm, last, end, 1);
L
Linus Torvalds 已提交
2530 2531 2532
		if (error)
			return error;
	}
2533
	vma = prev? prev->vm_next: mm->mmap;
L
Linus Torvalds 已提交
2534

2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548
	/*
	 * 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
2549 2550 2551
	/*
	 * Remove the vma's, and unmap the actual pages
	 */
2552 2553
	detach_vmas_to_be_unmapped(mm, vma, prev, end);
	unmap_region(mm, vma, prev, start, end);
L
Linus Torvalds 已提交
2554 2555

	/* Fix up all other VM information */
2556
	remove_vma_list(mm, vma);
L
Linus Torvalds 已提交
2557 2558 2559 2560

	return 0;
}

A
Al Viro 已提交
2561
int vm_munmap(unsigned long start, size_t len)
L
Linus Torvalds 已提交
2562 2563
{
	int ret;
A
Al Viro 已提交
2564
	struct mm_struct *mm = current->mm;
L
Linus Torvalds 已提交
2565 2566

	down_write(&mm->mmap_sem);
2567
	ret = do_munmap(mm, start, len);
L
Linus Torvalds 已提交
2568 2569 2570
	up_write(&mm->mmap_sem);
	return ret;
}
2571 2572 2573 2574 2575
EXPORT_SYMBOL(vm_munmap);

SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
{
	profile_munmap(addr);
A
Al Viro 已提交
2576
	return vm_munmap(addr, len);
2577
}
L
Linus Torvalds 已提交
2578 2579 2580

static inline void verify_mm_writelocked(struct mm_struct *mm)
{
2581
#ifdef CONFIG_DEBUG_VM
L
Linus Torvalds 已提交
2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593
	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.
 */
2594
static unsigned long do_brk(unsigned long addr, unsigned long len)
L
Linus Torvalds 已提交
2595 2596 2597 2598 2599 2600
{
	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;
2601
	int error;
L
Linus Torvalds 已提交
2602 2603 2604 2605 2606

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

2607 2608
	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

A
Al Viro 已提交
2609 2610
	error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
	if (error & ~PAGE_MASK)
2611 2612
		return error;

2613 2614 2615
	error = mlock_future_check(mm, mm->def_flags, len);
	if (error)
		return error;
L
Linus Torvalds 已提交
2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626

	/*
	 * 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:
2627
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
L
Linus Torvalds 已提交
2628 2629 2630 2631 2632 2633
		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
2634
	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2635 2636 2637 2638 2639
		return -ENOMEM;

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

2640
	if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2641 2642 2643
		return -ENOMEM;

	/* Can we just expand an old private anonymous mapping? */
2644 2645 2646
	vma = vma_merge(mm, prev, addr, addr + len, flags,
					NULL, NULL, pgoff, NULL);
	if (vma)
L
Linus Torvalds 已提交
2647 2648 2649 2650 2651
		goto out;

	/*
	 * create a vma struct for an anonymous mapping
	 */
P
Pekka Enberg 已提交
2652
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2653 2654 2655 2656 2657
	if (!vma) {
		vm_unacct_memory(len >> PAGE_SHIFT);
		return -ENOMEM;
	}

2658
	INIT_LIST_HEAD(&vma->anon_vma_chain);
L
Linus Torvalds 已提交
2659 2660 2661 2662 2663
	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;
	vma->vm_pgoff = pgoff;
	vma->vm_flags = flags;
2664
	vma->vm_page_prot = vm_get_page_prot(flags);
L
Linus Torvalds 已提交
2665 2666
	vma_link(mm, vma, prev, rb_link, rb_parent);
out:
2667
	perf_event_mmap(vma);
L
Linus Torvalds 已提交
2668
	mm->total_vm += len >> PAGE_SHIFT;
2669 2670
	if (flags & VM_LOCKED)
		mm->locked_vm += (len >> PAGE_SHIFT);
2671
	vma->vm_flags |= VM_SOFTDIRTY;
L
Linus Torvalds 已提交
2672 2673 2674
	return addr;
}

2675 2676 2677 2678
unsigned long vm_brk(unsigned long addr, unsigned long len)
{
	struct mm_struct *mm = current->mm;
	unsigned long ret;
2679
	bool populate;
2680 2681 2682

	down_write(&mm->mmap_sem);
	ret = do_brk(addr, len);
2683
	populate = ((mm->def_flags & VM_LOCKED) != 0);
2684
	up_write(&mm->mmap_sem);
2685 2686
	if (populate)
		mm_populate(addr, len);
2687 2688 2689
	return ret;
}
EXPORT_SYMBOL(vm_brk);
L
Linus Torvalds 已提交
2690 2691 2692 2693

/* Release all mmaps. */
void exit_mmap(struct mm_struct *mm)
{
P
Peter Zijlstra 已提交
2694
	struct mmu_gather tlb;
2695
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2696 2697
	unsigned long nr_accounted = 0;

2698
	/* mm's last user has gone, and its about to be pulled down */
A
Andrea Arcangeli 已提交
2699
	mmu_notifier_release(mm);
2700

2701 2702 2703 2704 2705 2706 2707 2708
	if (mm->locked_vm) {
		vma = mm->mmap;
		while (vma) {
			if (vma->vm_flags & VM_LOCKED)
				munlock_vma_pages_all(vma);
			vma = vma->vm_next;
		}
	}
2709 2710 2711

	arch_exit_mmap(mm);

2712
	vma = mm->mmap;
2713 2714 2715
	if (!vma)	/* Can happen if dup_mmap() received an OOM */
		return;

L
Linus Torvalds 已提交
2716 2717
	lru_add_drain();
	flush_cache_mm(mm);
2718
	tlb_gather_mmu(&tlb, mm, 0, -1);
2719
	/* update_hiwater_rss(mm) here? but nobody should be looking */
2720
	/* Use -1 here to ensure all VMAs in the mm are unmapped */
2721
	unmap_vmas(&tlb, vma, 0, -1);
H
Hugh Dickins 已提交
2722

2723
	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2724
	tlb_finish_mmu(&tlb, 0, -1);
L
Linus Torvalds 已提交
2725 2726

	/*
2727 2728
	 * Walk the list again, actually closing and freeing it,
	 * with preemption enabled, without holding any MM locks.
L
Linus Torvalds 已提交
2729
	 */
2730 2731 2732
	while (vma) {
		if (vma->vm_flags & VM_ACCOUNT)
			nr_accounted += vma_pages(vma);
2733
		vma = remove_vma(vma);
2734 2735
	}
	vm_unacct_memory(nr_accounted);
2736

2737 2738
	WARN_ON(atomic_long_read(&mm->nr_ptes) >
			(FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
L
Linus Torvalds 已提交
2739 2740 2741 2742
}

/* Insert vm structure into process list sorted by address
 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2743
 * then i_mmap_mutex is taken here.
L
Linus Torvalds 已提交
2744
 */
2745
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
2746
{
2747 2748
	struct vm_area_struct *prev;
	struct rb_node **rb_link, *rb_parent;
L
Linus Torvalds 已提交
2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765

	/*
	 * 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;
	}
2766 2767
	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
			   &prev, &rb_link, &rb_parent))
L
Linus Torvalds 已提交
2768
		return -ENOMEM;
2769
	if ((vma->vm_flags & VM_ACCOUNT) &&
2770
	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
2771
		return -ENOMEM;
2772

L
Linus Torvalds 已提交
2773 2774 2775 2776 2777 2778 2779 2780 2781
	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,
2782 2783
	unsigned long addr, unsigned long len, pgoff_t pgoff,
	bool *need_rmap_locks)
L
Linus Torvalds 已提交
2784 2785 2786 2787 2788 2789
{
	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;
2790
	bool faulted_in_anon_vma = true;
L
Linus Torvalds 已提交
2791 2792 2793 2794 2795

	/*
	 * If anonymous vma has not yet been faulted, update new pgoff
	 * to match new location, to increase its chance of merging.
	 */
2796
	if (unlikely(!vma->vm_file && !vma->anon_vma)) {
L
Linus Torvalds 已提交
2797
		pgoff = addr >> PAGE_SHIFT;
2798 2799
		faulted_in_anon_vma = false;
	}
L
Linus Torvalds 已提交
2800

2801 2802
	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
2803 2804 2805 2806 2807 2808
	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
		 */
2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823
		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);
2824
			*vmap = vma = new_vma;
2825
		}
2826
		*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
L
Linus Torvalds 已提交
2827
	} else {
2828
		new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2829 2830
		if (new_vma) {
			*new_vma = *vma;
2831 2832 2833
			new_vma->vm_start = addr;
			new_vma->vm_end = addr + len;
			new_vma->vm_pgoff = pgoff;
2834
			if (vma_dup_policy(vma, new_vma))
2835 2836 2837 2838
				goto out_free_vma;
			INIT_LIST_HEAD(&new_vma->anon_vma_chain);
			if (anon_vma_clone(new_vma, vma))
				goto out_free_mempol;
2839
			if (new_vma->vm_file)
L
Linus Torvalds 已提交
2840 2841 2842 2843
				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);
2844
			*need_rmap_locks = false;
L
Linus Torvalds 已提交
2845 2846 2847
		}
	}
	return new_vma;
2848 2849

 out_free_mempol:
2850
	mpol_put(vma_policy(new_vma));
2851 2852 2853
 out_free_vma:
	kmem_cache_free(vm_area_cachep, new_vma);
	return NULL;
L
Linus Torvalds 已提交
2854
}
A
akpm@osdl.org 已提交
2855 2856 2857 2858 2859 2860 2861 2862 2863 2864

/*
 * 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
2865
	lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
A
akpm@osdl.org 已提交
2866 2867 2868 2869 2870

	if (cur + npages > lim)
		return 0;
	return 1;
}
2871 2872


N
Nick Piggin 已提交
2873 2874
static int special_mapping_fault(struct vm_area_struct *vma,
				struct vm_fault *vmf)
2875
{
N
Nick Piggin 已提交
2876
	pgoff_t pgoff;
2877 2878
	struct page **pages;

N
Nick Piggin 已提交
2879 2880 2881 2882 2883 2884 2885
	/*
	 * 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;
2886

N
Nick Piggin 已提交
2887 2888
	for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
		pgoff--;
2889 2890 2891 2892

	if (*pages) {
		struct page *page = *pages;
		get_page(page);
N
Nick Piggin 已提交
2893 2894
		vmf->page = page;
		return 0;
2895 2896
	}

N
Nick Piggin 已提交
2897
	return VM_FAULT_SIGBUS;
2898 2899 2900 2901 2902 2903 2904 2905 2906
}

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

2907
static const struct vm_operations_struct special_mapping_vmops = {
2908
	.close = special_mapping_close,
N
Nick Piggin 已提交
2909
	.fault = special_mapping_fault,
2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920
};

/*
 * 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.
 */
2921
struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
2922 2923 2924
			    unsigned long addr, unsigned long len,
			    unsigned long vm_flags, struct page **pages)
{
2925
	int ret;
2926 2927 2928 2929
	struct vm_area_struct *vma;

	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (unlikely(vma == NULL))
2930
		return ERR_PTR(-ENOMEM);
2931

2932
	INIT_LIST_HEAD(&vma->anon_vma_chain);
2933 2934 2935 2936
	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;

2937
	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
2938
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2939 2940 2941 2942

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

2943 2944 2945
	ret = insert_vm_struct(mm, vma);
	if (ret)
		goto out;
2946 2947 2948

	mm->total_vm += len >> PAGE_SHIFT;

2949
	perf_event_mmap(vma);
2950

2951
	return vma;
2952 2953 2954

out:
	kmem_cache_free(vm_area_cachep, vma);
2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967
	return ERR_PTR(ret);
}

int install_special_mapping(struct mm_struct *mm,
			    unsigned long addr, unsigned long len,
			    unsigned long vm_flags, struct page **pages)
{
	struct vm_area_struct *vma = _install_special_mapping(mm,
			    addr, len, vm_flags, pages);

	if (IS_ERR(vma))
		return PTR_ERR(vma);
	return 0;
2968
}
2969 2970 2971

static DEFINE_MUTEX(mm_all_locks_mutex);

2972
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2973
{
2974
	if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
2975 2976 2977 2978
		/*
		 * The LSB of head.next can't change from under us
		 * because we hold the mm_all_locks_mutex.
		 */
2979
		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
2980 2981
		/*
		 * We can safely modify head.next after taking the
2982
		 * anon_vma->root->rwsem. If some other vma in this mm shares
2983 2984 2985 2986
		 * 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
2987
		 * anon_vma->root->rwsem.
2988 2989
		 */
		if (__test_and_set_bit(0, (unsigned long *)
2990
				       &anon_vma->root->rb_root.rb_node))
2991 2992 2993 2994
			BUG();
	}
}

2995
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008
{
	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();
3009
		mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030
	}
}

/*
 * 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.
 *
3031
 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3032 3033 3034 3035
 * 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
3036
 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047
 * 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;
3048
	struct anon_vma_chain *avc;
3049 3050 3051 3052 3053 3054 3055 3056 3057

	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)
3058
			vm_lock_mapping(mm, vma->vm_file->f_mapping);
3059
	}
3060 3061 3062 3063 3064

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (signal_pending(current))
			goto out_unlock;
		if (vma->anon_vma)
3065 3066
			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
				vm_lock_anon_vma(mm, avc->anon_vma);
3067
	}
3068

3069
	return 0;
3070 3071

out_unlock:
3072 3073
	mm_drop_all_locks(mm);
	return -EINTR;
3074 3075 3076 3077
}

static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
{
3078
	if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3079 3080 3081 3082 3083
		/*
		 * 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
3084
		 * the vma so the users using the anon_vma->rb_root will
3085 3086 3087 3088
		 * never see our bitflag.
		 *
		 * No need of atomic instructions here, head.next
		 * can't change from under us until we release the
3089
		 * anon_vma->root->rwsem.
3090 3091
		 */
		if (!__test_and_clear_bit(0, (unsigned long *)
3092
					  &anon_vma->root->rb_root.rb_node))
3093
			BUG();
3094
		anon_vma_unlock_write(anon_vma);
3095 3096 3097 3098 3099 3100 3101 3102 3103 3104
	}
}

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.
		 */
3105
		mutex_unlock(&mapping->i_mmap_mutex);
3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118
		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;
3119
	struct anon_vma_chain *avc;
3120 3121 3122 3123 3124 3125

	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)
3126 3127
			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
				vm_unlock_anon_vma(avc->anon_vma);
3128 3129 3130 3131 3132 3133
		if (vma->vm_file && vma->vm_file->f_mapping)
			vm_unlock_mapping(vma->vm_file->f_mapping);
	}

	mutex_unlock(&mm_all_locks_mutex);
}
3134 3135 3136 3137 3138 3139

/*
 * initialise the VMA slab
 */
void __init mmap_init(void)
{
3140 3141 3142 3143
	int ret;

	ret = percpu_counter_init(&vm_committed_as, 0);
	VM_BUG_ON(ret);
3144
}
3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155

/*
 * 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.
 */
3156
static int init_user_reserve(void)
3157 3158 3159 3160 3161 3162 3163 3164
{
	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;
}
3165
subsys_initcall(init_user_reserve);
3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176

/*
 * 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.
 */
3177
static int init_admin_reserve(void)
3178 3179 3180 3181 3182 3183 3184 3185
{
	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;
}
3186
subsys_initcall(init_admin_reserve);
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 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255

/*
 * 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;
}
3256
subsys_initcall(init_reserve_notifier);