mmap.c 88.5 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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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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>
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#include <linux/vmacache.h>
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#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/mmdebug.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 <linux/printk.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
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 *
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 * 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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static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
{
	return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
}

/* Update vma->vm_page_prot to reflect vma->vm_flags. */
void vma_set_page_prot(struct vm_area_struct *vma)
{
	unsigned long vm_flags = vma->vm_flags;

	vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
	if (vma_wants_writenotify(vma)) {
		vm_flags &= ~VM_SHARED;
		vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot,
						     vm_flags);
	}
}


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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_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
			-(s64)vm_committed_as_batch * num_online_cpus(),
			"memory commitment underflow");

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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)
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		mapping_unmap_writable(mapping);
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	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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		i_mmap_lock_write(mapping);
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		__remove_shared_vm_struct(vma, file, mapping);
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		i_mmap_unlock_write(mapping);
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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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{
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	unsigned long retval;
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	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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	if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
			      mm->end_data, mm->start_data))
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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) {
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			pr_emerg("vm_start %lx < prev %lx\n",
				  vma->vm_start, prev);
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			bug = 1;
		}
		if (vma->vm_start < pend) {
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			pr_emerg("vm_start %lx < pend %lx\n",
				  vma->vm_start, pend);
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			bug = 1;
		}
		if (vma->vm_start > vma->vm_end) {
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			pr_emerg("vm_start %lx > vm_end %lx\n",
				  vma->vm_start, vma->vm_end);
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			bug = 1;
		}
		if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
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			pr_emerg("free gap %lx, correct %lx\n",
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			       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) {
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		pr_emerg("backwards %d, forwards %d\n", j, i);
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		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);
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		VM_BUG_ON_VMA(vma != ignore &&
			vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
			vma);
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	}
}

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static void validate_mm(struct mm_struct *mm)
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{
	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;
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	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) {
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		pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
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		bug = 1;
	}
	if (highest_address != mm->highest_vm_end) {
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		pr_emerg("mm->highest_vm_end %lx, found %lx\n",
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			  mm->highest_vm_end, highest_address);
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		bug = 1;
	}
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	i = browse_rb(&mm->mm_rb);
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	if (i != mm->map_count) {
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		if (i != -1)
			pr_emerg("map_count %d rb %d\n", mm->map_count, i);
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		bug = 1;
	}
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	VM_BUG_ON_MM(bug, mm);
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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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{
556
	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) {
568 569 570
			/* 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;
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	return 0;
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}

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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)
{
617 618 619 620 621 622 623 624 625 626 627 628 629 630 631
	/* 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);
633 634 635
	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)
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			atomic_inc(&mapping->i_mmap_writable);
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		flush_dcache_mmap_lock(mapping);
		if (unlikely(vma->vm_flags & VM_NONLINEAR))
			vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
		else
655
			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;

675
	if (vma->vm_file) {
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		mapping = vma->vm_file->f_mapping;
677
		i_mmap_lock_write(mapping);
678
	}
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	__vma_link(mm, vma, prev, rb_link, rb_parent);
	__vma_link_file(vma);

	if (mapping)
684
		i_mmap_unlock_write(mapping);
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	mm->map_count++;
	validate_mm(mm);
}

/*
691
 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
692
 * 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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{
696
	struct vm_area_struct *prev;
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	struct rb_node **rb_link, *rb_parent;
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	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)
{
710
	struct vm_area_struct *next;
711

712 713
	vma_rb_erase(vma, &mm->mm_rb);
	prev->vm_next = next = vma->vm_next;
714 715
	if (next)
		next->vm_prev = prev;
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	/* Kill the cache */
	vmacache_invalidate(mm);
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}

/*
 * 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.
 */
728
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;
735
	struct rb_root *root = NULL;
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	struct anon_vma *anon_vma = NULL;
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	struct file *file = vma->vm_file;
738
	bool start_changed = false, end_changed = false;
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	long adjust_next = 0;
	int remove_next = 0;

	if (next && !insert) {
743 744
		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;
752
			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;
760
			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.
			 */
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			adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
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			exporter = vma;
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			importer = next;
		}

773 774 775 776 777
		/*
		 * 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.
		 */
778
		if (exporter && exporter->anon_vma && !importer->anon_vma) {
779 780 781 782 783
			int error;

			error = anon_vma_clone(importer, exporter);
			if (error)
				return error;
784
			importer->anon_vma = exporter->anon_vma;
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		}
	}

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	if (file) {
		mapping = file->f_mapping;
790
		if (!(vma->vm_flags & VM_NONLINEAR)) {
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			root = &mapping->i_mmap;
792
			uprobe_munmap(vma, vma->vm_start, vma->vm_end);
793 794

			if (adjust_next)
795 796
				uprobe_munmap(next, next->vm_start,
							next->vm_end);
797 798
		}

799
		i_mmap_lock_write(mapping);
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		if (insert) {
			/*
802
			 * 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);
		}
	}

811 812
	vma_adjust_trans_huge(vma, start, end, adjust_next);

813 814 815 816
	anon_vma = vma->anon_vma;
	if (!anon_vma && adjust_next)
		anon_vma = next->anon_vma;
	if (anon_vma) {
817 818
		VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
			  anon_vma != next->anon_vma, next);
819
		anon_vma_lock_write(anon_vma);
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		anon_vma_interval_tree_pre_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_pre_update_vma(next);
	}
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	if (root) {
		flush_dcache_mmap_lock(mapping);
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		vma_interval_tree_remove(vma, root);
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		if (adjust_next)
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			vma_interval_tree_remove(next, root);
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	}

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	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)
848 849
			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);
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	} 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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	}

879 880 881 882
	if (anon_vma) {
		anon_vma_interval_tree_post_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_post_update_vma(next);
883
		anon_vma_unlock_write(anon_vma);
884
	}
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	if (mapping)
886
		i_mmap_unlock_write(mapping);
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888
	if (root) {
889
		uprobe_mmap(vma);
890 891

		if (adjust_next)
892
			uprobe_mmap(next);
893 894
	}

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	if (remove_next) {
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		if (file) {
897
			uprobe_munmap(next, next->vm_start, next->vm_end);
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			fput(file);
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		}
900 901
		if (next->anon_vma)
			anon_vma_merge(vma, next);
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		mm->map_count--;
903
		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.
		 */
910 911
		next = vma->vm_next;
		if (remove_next == 2)
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			goto again;
913 914 915 916
		else if (next)
			vma_gap_update(next);
		else
			mm->highest_vm_end = end;
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	}
918
	if (insert && file)
919
		uprobe_mmap(insert);
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	validate_mm(mm);
922 923

	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)
{
933 934 935 936 937 938 939 940 941
	/*
	 * 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) &&
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Shaohua Li 已提交
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	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
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		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) &&
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Shaohua Li 已提交
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	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
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		pgoff_t vm_pglen;
1001
		vm_pglen = vma_pages(vma);
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		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,
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			struct anon_vma *anon_vma, struct file *file,
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			pgoff_t pgoff, struct mempolicy *policy)
{
	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
	struct vm_area_struct *area, *next;
1045
	int err;
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1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065

	/*
	 * 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 &&
V
vishnu.ps 已提交
1066
			mpol_equal(vma_policy(prev), policy) &&
L
Linus Torvalds 已提交
1067 1068 1069 1070 1071 1072 1073 1074 1075 1076
			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
1077
						      next->anon_vma, NULL)) {
L
Linus Torvalds 已提交
1078
							/* cases 1, 6 */
1079
			err = vma_adjust(prev, prev->vm_start,
L
Linus Torvalds 已提交
1080 1081
				next->vm_end, prev->vm_pgoff, NULL);
		} else					/* cases 2, 5, 7 */
1082
			err = vma_adjust(prev, prev->vm_start,
L
Linus Torvalds 已提交
1083
				end, prev->vm_pgoff, NULL);
1084 1085
		if (err)
			return NULL;
1086
		khugepaged_enter_vma_merge(prev, vm_flags);
L
Linus Torvalds 已提交
1087 1088 1089 1090 1091 1092 1093
		return prev;
	}

	/*
	 * Can this new request be merged in front of next?
	 */
	if (next && end == next->vm_start &&
V
vishnu.ps 已提交
1094
			mpol_equal(policy, vma_policy(next)) &&
L
Linus Torvalds 已提交
1095 1096 1097
			can_vma_merge_before(next, vm_flags,
					anon_vma, file, pgoff+pglen)) {
		if (prev && addr < prev->vm_end)	/* case 4 */
1098
			err = vma_adjust(prev, prev->vm_start,
L
Linus Torvalds 已提交
1099 1100
				addr, prev->vm_pgoff, NULL);
		else					/* cases 3, 8 */
1101
			err = vma_adjust(area, addr, next->vm_end,
L
Linus Torvalds 已提交
1102
				next->vm_pgoff - pglen, NULL);
1103 1104
		if (err)
			return NULL;
1105
		khugepaged_enter_vma_merge(area, vm_flags);
L
Linus Torvalds 已提交
1106 1107 1108 1109 1110 1111
		return area;
	}

	return NULL;
}

1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129
/*
 * 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 &&
1130
		!((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166
		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
1167 1168 1169 1170 1171 1172 1173 1174 1175 1176
/*
 * 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)
{
1177
	struct anon_vma *anon_vma;
L
Linus Torvalds 已提交
1178 1179 1180 1181 1182 1183
	struct vm_area_struct *near;

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

1184 1185 1186
	anon_vma = reusable_anon_vma(near, vma, near);
	if (anon_vma)
		return anon_vma;
L
Linus Torvalds 已提交
1187
try_prev:
1188
	near = vma->vm_prev;
L
Linus Torvalds 已提交
1189 1190 1191
	if (!near)
		goto none;

1192 1193 1194
	anon_vma = reusable_anon_vma(near, near, vma);
	if (anon_vma)
		return anon_vma;
L
Linus Torvalds 已提交
1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207
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
1208
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
L
Linus Torvalds 已提交
1209 1210 1211 1212 1213
						struct file *file, long pages)
{
	const unsigned long stack_flags
		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);

1214 1215
	mm->total_vm += pages;

L
Linus Torvalds 已提交
1216 1217 1218 1219 1220 1221 1222 1223 1224
	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
1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237
/*
 * 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;
}

1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255
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
1256
/*
1257
 * The caller must hold down_write(&current->mm->mmap_sem).
L
Linus Torvalds 已提交
1258 1259
 */

1260
unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
L
Linus Torvalds 已提交
1261
			unsigned long len, unsigned long prot,
1262
			unsigned long flags, unsigned long pgoff,
1263
			unsigned long *populate)
L
Linus Torvalds 已提交
1264
{
V
vishnu.ps 已提交
1265
	struct mm_struct *mm = current->mm;
1266
	vm_flags_t vm_flags;
L
Linus Torvalds 已提交
1267

1268
	*populate = 0;
1269

L
Linus Torvalds 已提交
1270 1271 1272 1273 1274 1275 1276
	/*
	 * 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))
1277
		if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
L
Linus Torvalds 已提交
1278 1279 1280 1281 1282
			prot |= PROT_EXEC;

	if (!len)
		return -EINVAL;

1283 1284 1285
	if (!(flags & MAP_FIXED))
		addr = round_hint_to_min(addr);

L
Linus Torvalds 已提交
1286 1287
	/* Careful about overflows.. */
	len = PAGE_ALIGN(len);
1288
	if (!len)
L
Linus Torvalds 已提交
1289 1290 1291 1292
		return -ENOMEM;

	/* offset overflow? */
	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
V
vishnu.ps 已提交
1293
		return -EOVERFLOW;
L
Linus Torvalds 已提交
1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312

	/* 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
1313
	if (flags & MAP_LOCKED)
L
Linus Torvalds 已提交
1314 1315
		if (!can_do_mlock())
			return -EPERM;
1316

1317 1318
	if (mlock_future_check(mm, vm_flags, len))
		return -EAGAIN;
L
Linus Torvalds 已提交
1319 1320

	if (file) {
1321 1322
		struct inode *inode = file_inode(file);

L
Linus Torvalds 已提交
1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337
		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.
			 */
1338
			if (locks_verify_locked(file))
L
Linus Torvalds 已提交
1339 1340 1341 1342 1343 1344 1345 1346 1347 1348
				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;
1349
			if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
L
Linus Torvalds 已提交
1350 1351 1352 1353 1354
				if (vm_flags & VM_EXEC)
					return -EPERM;
				vm_flags &= ~VM_MAYEXEC;
			}

A
Al Viro 已提交
1355
			if (!file->f_op->mmap)
L
Linus Torvalds 已提交
1356
				return -ENODEV;
1357 1358
			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
				return -EINVAL;
L
Linus Torvalds 已提交
1359 1360 1361 1362 1363 1364 1365 1366
			break;

		default:
			return -EINVAL;
		}
	} else {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
1367 1368
			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
				return -EINVAL;
1369 1370 1371 1372
			/*
			 * Ignore pgoff.
			 */
			pgoff = 0;
L
Linus Torvalds 已提交
1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385
			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;
		}
	}

1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400
	/*
	 * 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);
1401 1402 1403
	if (!IS_ERR_VALUE(addr) &&
	    ((vm_flags & VM_LOCKED) ||
	     (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1404
		*populate = len;
1405
	return addr;
M
Miklos Szeredi 已提交
1406
}
1407

H
Hugh Dickins 已提交
1408 1409 1410 1411 1412 1413 1414 1415
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
1416
		audit_mmap_fd(fd, flags);
H
Hugh Dickins 已提交
1417 1418 1419
		file = fget(fd);
		if (!file)
			goto out;
1420 1421
		if (is_file_hugepages(file))
			len = ALIGN(len, huge_page_size(hstate_file(file)));
1422 1423 1424
		retval = -EINVAL;
		if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
			goto out_fput;
H
Hugh Dickins 已提交
1425 1426
	} else if (flags & MAP_HUGETLB) {
		struct user_struct *user = NULL;
1427
		struct hstate *hs;
1428

1429
		hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1430 1431 1432 1433
		if (!hs)
			return -EINVAL;

		len = ALIGN(len, huge_page_size(hs));
H
Hugh Dickins 已提交
1434 1435 1436 1437 1438 1439
		/*
		 * 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
		 */
1440
		file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1441 1442 1443
				VM_NORESERVE,
				&user, HUGETLB_ANONHUGE_INODE,
				(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
H
Hugh Dickins 已提交
1444 1445 1446 1447 1448 1449
		if (IS_ERR(file))
			return PTR_ERR(file);
	}

	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);

A
Al Viro 已提交
1450
	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1451
out_fput:
H
Hugh Dickins 已提交
1452 1453 1454 1455 1456 1457
	if (file)
		fput(file);
out:
	return retval;
}

C
Christoph Hellwig 已提交
1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481
#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
1482 1483 1484 1485 1486 1487 1488 1489
/*
 * 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)
{
1490
	vm_flags_t vm_flags = vma->vm_flags;
A
Alexey Dobriyan 已提交
1491 1492 1493 1494 1495 1496 1497 1498 1499

	/* 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;

1500 1501
	/* The open routine did something to the protections that pgprot_modify
	 * won't preserve? */
A
Alexey Dobriyan 已提交
1502
	if (pgprot_val(vma->vm_page_prot) !=
1503
	    pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
A
Alexey Dobriyan 已提交
1504 1505
		return 0;

1506 1507 1508 1509
	/* Do we need to track softdirty? */
	if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
		return 1;

A
Alexey Dobriyan 已提交
1510
	/* Specialty mapping? */
1511
	if (vm_flags & VM_PFNMAP)
A
Alexey Dobriyan 已提交
1512 1513 1514 1515 1516 1517 1518
		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);
}

1519 1520
/*
 * We account for memory if it's a private writeable mapping,
1521
 * not hugepages and VM_NORESERVE wasn't set.
1522
 */
1523
static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1524
{
1525 1526 1527 1528 1529 1530 1531
	/*
	 * 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;

1532 1533 1534
	return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
}

M
Miklos Szeredi 已提交
1535
unsigned long mmap_region(struct file *file, unsigned long addr,
1536
		unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
M
Miklos Szeredi 已提交
1537 1538 1539 1540 1541 1542 1543
{
	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;

1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560
	/* 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
1561 1562 1563
	/* Clear old maps */
	error = -ENOMEM;
munmap_back:
1564
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
L
Linus Torvalds 已提交
1565 1566 1567 1568 1569
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

1570 1571 1572
	/*
	 * Private writable mapping: check memory availability
	 */
1573
	if (accountable_mapping(file, vm_flags)) {
1574
		charged = len >> PAGE_SHIFT;
1575
		if (security_vm_enough_memory_mm(mm, charged))
1576 1577
			return -ENOMEM;
		vm_flags |= VM_ACCOUNT;
L
Linus Torvalds 已提交
1578 1579 1580
	}

	/*
1581
	 * Can we just expand an old mapping?
L
Linus Torvalds 已提交
1582
	 */
1583 1584 1585
	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
	if (vma)
		goto out;
L
Linus Torvalds 已提交
1586 1587 1588 1589 1590 1591

	/*
	 * 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
1592
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
1593 1594 1595 1596 1597 1598 1599 1600 1601
	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;
1602
	vma->vm_page_prot = vm_get_page_prot(vm_flags);
L
Linus Torvalds 已提交
1603
	vma->vm_pgoff = pgoff;
1604
	INIT_LIST_HEAD(&vma->anon_vma_chain);
L
Linus Torvalds 已提交
1605 1606 1607 1608 1609 1610 1611

	if (file) {
		if (vm_flags & VM_DENYWRITE) {
			error = deny_write_access(file);
			if (error)
				goto free_vma;
		}
1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622
		if (vm_flags & VM_SHARED) {
			error = mapping_map_writable(file->f_mapping);
			if (error)
				goto allow_write_and_free_vma;
		}

		/* ->mmap() can change vma->vm_file, but must guarantee that
		 * vma_link() below can deny write-access if VM_DENYWRITE is set
		 * and map writably if VM_SHARED is set. This usually means the
		 * new file must not have been exposed to user-space, yet.
		 */
A
Al Viro 已提交
1623
		vma->vm_file = get_file(file);
L
Linus Torvalds 已提交
1624 1625 1626
		error = file->f_op->mmap(file, vma);
		if (error)
			goto unmap_and_free_vma;
1627 1628 1629 1630 1631

		/* Can addr have changed??
		 *
		 * Answer: Yes, several device drivers can do it in their
		 *         f_op->mmap method. -DaveM
1632 1633
		 * Bug: If addr is changed, prev, rb_link, rb_parent should
		 *      be updated for vma_link()
1634
		 */
1635 1636
		WARN_ON_ONCE(addr != vma->vm_start);

1637 1638
		addr = vma->vm_start;
		vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
1639 1640 1641 1642 1643 1644
	} else if (vm_flags & VM_SHARED) {
		error = shmem_zero_setup(vma);
		if (error)
			goto free_vma;
	}

1645
	vma_link(mm, vma, prev, rb_link, rb_parent);
1646
	/* Once vma denies write, undo our temporary denial count */
1647 1648 1649 1650 1651 1652
	if (file) {
		if (vm_flags & VM_SHARED)
			mapping_unmap_writable(file->f_mapping);
		if (vm_flags & VM_DENYWRITE)
			allow_write_access(file);
	}
1653
	file = vma->vm_file;
1654
out:
1655
	perf_event_mmap(vma);
1656

1657
	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
L
Linus Torvalds 已提交
1658
	if (vm_flags & VM_LOCKED) {
1659 1660
		if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
					vma == get_gate_vma(current->mm)))
1661
			mm->locked_vm += (len >> PAGE_SHIFT);
1662 1663 1664
		else
			vma->vm_flags &= ~VM_LOCKED;
	}
1665

1666 1667
	if (file)
		uprobe_mmap(vma);
1668

1669 1670 1671 1672 1673 1674 1675 1676 1677
	/*
	 * 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;

1678 1679
	vma_set_page_prot(vma);

L
Linus Torvalds 已提交
1680 1681 1682 1683 1684 1685 1686
	return addr;

unmap_and_free_vma:
	vma->vm_file = NULL;
	fput(file);

	/* Undo any partial mapping done by a device driver. */
1687 1688
	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
	charged = 0;
1689 1690 1691 1692 1693
	if (vm_flags & VM_SHARED)
		mapping_unmap_writable(file->f_mapping);
allow_write_and_free_vma:
	if (vm_flags & VM_DENYWRITE)
		allow_write_access(file);
L
Linus Torvalds 已提交
1694 1695 1696 1697 1698 1699 1700 1701
free_vma:
	kmem_cache_free(vm_area_cachep, vma);
unacct_error:
	if (charged)
		vm_unacct_memory(charged);
	return error;
}

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 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901
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
1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919
/* 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;
1920
	struct vm_unmapped_area_info info;
L
Linus Torvalds 已提交
1921

1922
	if (len > TASK_SIZE - mmap_min_addr)
L
Linus Torvalds 已提交
1923 1924
		return -ENOMEM;

1925 1926 1927
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1928 1929 1930
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
1931
		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
L
Linus Torvalds 已提交
1932 1933 1934 1935
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}

1936 1937
	info.flags = 0;
	info.length = len;
1938
	info.low_limit = mm->mmap_base;
1939 1940 1941
	info.high_limit = TASK_SIZE;
	info.align_mask = 0;
	return vm_unmapped_area(&info);
L
Linus Torvalds 已提交
1942
}
V
vishnu.ps 已提交
1943
#endif
L
Linus Torvalds 已提交
1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956

/*
 * 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;
1957 1958
	unsigned long addr = addr0;
	struct vm_unmapped_area_info info;
L
Linus Torvalds 已提交
1959 1960

	/* requested length too big for entire address space */
1961
	if (len > TASK_SIZE - mmap_min_addr)
L
Linus Torvalds 已提交
1962 1963
		return -ENOMEM;

1964 1965 1966
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1967 1968 1969 1970
	/* requesting a specific address */
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
1971
		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
L
Linus Torvalds 已提交
1972 1973 1974 1975
				(!vma || addr + len <= vma->vm_start))
			return addr;
	}

1976 1977
	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
1978
	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1979 1980 1981
	info.high_limit = mm->mmap_base;
	info.align_mask = 0;
	addr = vm_unmapped_area(&info);
1982

L
Linus Torvalds 已提交
1983 1984 1985 1986 1987 1988
	/*
	 * 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.
	 */
1989 1990 1991 1992 1993 1994 1995
	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
1996 1997 1998 1999 2000 2001 2002 2003 2004

	return addr;
}
#endif

unsigned long
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
2005 2006 2007
	unsigned long (*get_area)(struct file *, unsigned long,
				  unsigned long, unsigned long, unsigned long);

2008 2009 2010 2011 2012 2013 2014 2015
	unsigned long error = arch_mmap_check(addr, len, flags);
	if (error)
		return error;

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

2016
	get_area = current->mm->get_unmapped_area;
A
Al Viro 已提交
2017
	if (file && file->f_op->get_unmapped_area)
2018 2019 2020 2021
		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
2022

2023 2024 2025 2026
	if (addr > TASK_SIZE - len)
		return -ENOMEM;
	if (addr & ~PAGE_MASK)
		return -EINVAL;
2027

2028 2029 2030
	addr = arch_rebalance_pgtables(addr, len);
	error = security_mmap_addr(addr);
	return error ? error : addr;
L
Linus Torvalds 已提交
2031 2032 2033 2034 2035
}

EXPORT_SYMBOL(get_unmapped_area);

/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
Z
ZhenwenXu 已提交
2036
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
2037
{
D
Davidlohr Bueso 已提交
2038 2039
	struct rb_node *rb_node;
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2040

2041
	/* Check the cache first. */
D
Davidlohr Bueso 已提交
2042 2043 2044
	vma = vmacache_find(mm, addr);
	if (likely(vma))
		return vma;
2045

D
Davidlohr Bueso 已提交
2046 2047
	rb_node = mm->mm_rb.rb_node;
	vma = NULL;
2048

D
Davidlohr Bueso 已提交
2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060
	while (rb_node) {
		struct vm_area_struct *tmp;

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

		if (tmp->vm_end > addr) {
			vma = tmp;
			if (tmp->vm_start <= addr)
				break;
			rb_node = rb_node->rb_left;
		} else
			rb_node = rb_node->rb_right;
L
Linus Torvalds 已提交
2061
	}
D
Davidlohr Bueso 已提交
2062 2063 2064

	if (vma)
		vmacache_update(addr, vma);
L
Linus Torvalds 已提交
2065 2066 2067 2068 2069
	return vma;
}

EXPORT_SYMBOL(find_vma);

K
KOSAKI Motohiro 已提交
2070 2071 2072
/*
 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
 */
L
Linus Torvalds 已提交
2073 2074 2075 2076
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
2077
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2078

K
KOSAKI Motohiro 已提交
2079
	vma = find_vma(mm, addr);
M
Mikulas Patocka 已提交
2080 2081 2082 2083 2084 2085 2086 2087 2088 2089
	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
2090
	return vma;
L
Linus Torvalds 已提交
2091 2092 2093 2094 2095 2096 2097
}

/*
 * 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
2098
static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
L
Linus Torvalds 已提交
2099 2100 2101
{
	struct mm_struct *mm = vma->vm_mm;
	struct rlimit *rlim = current->signal->rlim;
2102
	unsigned long new_start;
L
Linus Torvalds 已提交
2103 2104

	/* address space limit tests */
A
akpm@osdl.org 已提交
2105
	if (!may_expand_vm(mm, grow))
L
Linus Torvalds 已提交
2106 2107 2108
		return -ENOMEM;

	/* Stack limit test */
J
Jiri Slaby 已提交
2109
	if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
L
Linus Torvalds 已提交
2110 2111 2112 2113 2114 2115 2116
		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
2117 2118
		limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
		limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
2119 2120 2121 2122
		if (locked > limit && !capable(CAP_IPC_LOCK))
			return -ENOMEM;
	}

2123 2124 2125 2126 2127 2128
	/* 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
2129 2130 2131 2132
	/*
	 * Overcommit..  This must be the final test, as it will
	 * update security statistics.
	 */
2133
	if (security_vm_enough_memory_mm(mm, grow))
L
Linus Torvalds 已提交
2134 2135 2136 2137 2138
		return -ENOMEM;

	/* Ok, everything looks good - let it rip */
	if (vma->vm_flags & VM_LOCKED)
		mm->locked_vm += grow;
2139
	vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
L
Linus Torvalds 已提交
2140 2141 2142
	return 0;
}

H
Hugh Dickins 已提交
2143
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
L
Linus Torvalds 已提交
2144
/*
H
Hugh Dickins 已提交
2145 2146
 * 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
2147
 */
H
Hugh Dickins 已提交
2148
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
L
Linus Torvalds 已提交
2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160
{
	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;
2161
	vma_lock_anon_vma(vma);
L
Linus Torvalds 已提交
2162 2163 2164 2165 2166

	/*
	 * 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.
2167
	 * Also guard against wrapping around to address 0.
L
Linus Torvalds 已提交
2168
	 */
2169 2170 2171
	if (address < PAGE_ALIGN(address+4))
		address = PAGE_ALIGN(address+4);
	else {
2172
		vma_unlock_anon_vma(vma);
2173 2174
		return -ENOMEM;
	}
L
Linus Torvalds 已提交
2175 2176 2177 2178 2179 2180 2181 2182 2183
	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;

2184 2185 2186 2187
		error = -ENOMEM;
		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
			error = acct_stack_growth(vma, size, grow);
			if (!error) {
2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199
				/*
				 * 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);
2200
				anon_vma_interval_tree_pre_update_vma(vma);
2201
				vma->vm_end = address;
2202
				anon_vma_interval_tree_post_update_vma(vma);
2203 2204 2205 2206
				if (vma->vm_next)
					vma_gap_update(vma->vm_next);
				else
					vma->vm_mm->highest_vm_end = address;
2207 2208
				spin_unlock(&vma->vm_mm->page_table_lock);

2209 2210
				perf_event_mmap(vma);
			}
2211
		}
L
Linus Torvalds 已提交
2212
	}
2213
	vma_unlock_anon_vma(vma);
2214
	khugepaged_enter_vma_merge(vma, vma->vm_flags);
2215
	validate_mm(vma->vm_mm);
L
Linus Torvalds 已提交
2216 2217
	return error;
}
H
Hugh Dickins 已提交
2218 2219
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */

L
Linus Torvalds 已提交
2220 2221 2222
/*
 * vma is the first one with address < vma->vm_start.  Have to extend vma.
 */
2223
int expand_downwards(struct vm_area_struct *vma,
2224
				   unsigned long address)
L
Linus Torvalds 已提交
2225 2226 2227 2228 2229 2230 2231 2232 2233
{
	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;
2234 2235

	address &= PAGE_MASK;
2236
	error = security_mmap_addr(address);
2237 2238 2239
	if (error)
		return error;

2240
	vma_lock_anon_vma(vma);
L
Linus Torvalds 已提交
2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254

	/*
	 * 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;

2255 2256 2257 2258
		error = -ENOMEM;
		if (grow <= vma->vm_pgoff) {
			error = acct_stack_growth(vma, size, grow);
			if (!error) {
2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270
				/*
				 * 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);
2271
				anon_vma_interval_tree_pre_update_vma(vma);
2272 2273
				vma->vm_start = address;
				vma->vm_pgoff -= grow;
2274
				anon_vma_interval_tree_post_update_vma(vma);
2275
				vma_gap_update(vma);
2276 2277
				spin_unlock(&vma->vm_mm->page_table_lock);

2278 2279
				perf_event_mmap(vma);
			}
L
Linus Torvalds 已提交
2280 2281
		}
	}
2282
	vma_unlock_anon_vma(vma);
2283
	khugepaged_enter_vma_merge(vma, vma->vm_flags);
2284
	validate_mm(vma->vm_mm);
L
Linus Torvalds 已提交
2285 2286 2287
	return error;
}

2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298
/*
 * 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.
 */
2299 2300 2301
#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
2302 2303 2304 2305 2306 2307 2308 2309
	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;
	}
2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321
	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;
2322
	if (!prev || expand_stack(prev, addr))
2323
		return NULL;
2324 2325
	if (prev->vm_flags & VM_LOCKED)
		__mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);
2326 2327 2328 2329 2330
	return prev;
}
#else
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
2331 2332 2333 2334 2335 2336 2337 2338
	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;
	}
2339 2340 2341
	return expand_downwards(vma, address);
}

L
Linus Torvalds 已提交
2342
struct vm_area_struct *
V
vishnu.ps 已提交
2343
find_extend_vma(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
2344
{
V
vishnu.ps 已提交
2345
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2346 2347 2348
	unsigned long start;

	addr &= PAGE_MASK;
V
vishnu.ps 已提交
2349
	vma = find_vma(mm, addr);
L
Linus Torvalds 已提交
2350 2351 2352 2353 2354 2355 2356 2357 2358
	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;
2359 2360
	if (vma->vm_flags & VM_LOCKED)
		__mlock_vma_pages_range(vma, addr, start, NULL);
L
Linus Torvalds 已提交
2361 2362 2363 2364 2365
	return vma;
}
#endif

/*
2366
 * Ok - we have the memory areas we should free on the vma list,
L
Linus Torvalds 已提交
2367
 * so release them, and do the vma updates.
2368 2369
 *
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
2370
 */
2371
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
2372
{
2373 2374
	unsigned long nr_accounted = 0;

2375 2376
	/* Update high watermark before we lower total_vm */
	update_hiwater_vm(mm);
L
Linus Torvalds 已提交
2377
	do {
2378 2379
		long nrpages = vma_pages(vma);

2380 2381
		if (vma->vm_flags & VM_ACCOUNT)
			nr_accounted += nrpages;
2382
		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2383
		vma = remove_vma(vma);
2384
	} while (vma);
2385
	vm_unacct_memory(nr_accounted);
L
Linus Torvalds 已提交
2386 2387 2388 2389 2390 2391
	validate_mm(mm);
}

/*
 * Get rid of page table information in the indicated region.
 *
2392
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
2393 2394
 */
static void unmap_region(struct mm_struct *mm,
2395 2396
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end)
L
Linus Torvalds 已提交
2397
{
V
vishnu.ps 已提交
2398
	struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
P
Peter Zijlstra 已提交
2399
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
2400 2401

	lru_add_drain();
2402
	tlb_gather_mmu(&tlb, mm, start, end);
2403
	update_hiwater_rss(mm);
2404
	unmap_vmas(&tlb, vma, start, end);
P
Peter Zijlstra 已提交
2405
	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2406
				 next ? next->vm_start : USER_PGTABLES_CEILING);
P
Peter Zijlstra 已提交
2407
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421
}

/*
 * 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);
2422
	vma->vm_prev = NULL;
L
Linus Torvalds 已提交
2423
	do {
2424
		vma_rb_erase(vma, &mm->mm_rb);
L
Linus Torvalds 已提交
2425 2426 2427 2428 2429
		mm->map_count--;
		tail_vma = vma;
		vma = vma->vm_next;
	} while (vma && vma->vm_start < end);
	*insertion_point = vma;
2430
	if (vma) {
2431
		vma->vm_prev = prev;
2432 2433 2434
		vma_gap_update(vma);
	} else
		mm->highest_vm_end = prev ? prev->vm_end : 0;
L
Linus Torvalds 已提交
2435
	tail_vma->vm_next = NULL;
D
Davidlohr Bueso 已提交
2436 2437 2438

	/* Kill the cache */
	vmacache_invalidate(mm);
L
Linus Torvalds 已提交
2439 2440 2441
}

/*
2442 2443
 * __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
2444
 */
V
vishnu.ps 已提交
2445
static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2446 2447 2448
	      unsigned long addr, int new_below)
{
	struct vm_area_struct *new;
2449
	int err = -ENOMEM;
L
Linus Torvalds 已提交
2450

2451 2452
	if (is_vm_hugetlb_page(vma) && (addr &
					~(huge_page_mask(hstate_vma(vma)))))
L
Linus Torvalds 已提交
2453 2454
		return -EINVAL;

2455
	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2456
	if (!new)
2457
		goto out_err;
L
Linus Torvalds 已提交
2458 2459 2460 2461

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

2462 2463
	INIT_LIST_HEAD(&new->anon_vma_chain);

L
Linus Torvalds 已提交
2464 2465 2466 2467 2468 2469 2470
	if (new_below)
		new->vm_end = addr;
	else {
		new->vm_start = addr;
		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
	}

2471 2472
	err = vma_dup_policy(vma, new);
	if (err)
2473
		goto out_free_vma;
L
Linus Torvalds 已提交
2474

2475 2476
	err = anon_vma_clone(new, vma);
	if (err)
2477 2478
		goto out_free_mpol;

2479
	if (new->vm_file)
L
Linus Torvalds 已提交
2480 2481 2482 2483 2484 2485
		get_file(new->vm_file);

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

	if (new_below)
2486
		err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
L
Linus Torvalds 已提交
2487 2488
			((addr - new->vm_start) >> PAGE_SHIFT), new);
	else
2489
		err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
L
Linus Torvalds 已提交
2490

2491 2492 2493 2494 2495
	/* Success. */
	if (!err)
		return 0;

	/* Clean everything up if vma_adjust failed. */
2496 2497
	if (new->vm_ops && new->vm_ops->close)
		new->vm_ops->close(new);
2498
	if (new->vm_file)
2499
		fput(new->vm_file);
2500
	unlink_anon_vmas(new);
2501
 out_free_mpol:
2502
	mpol_put(vma_policy(new));
2503 2504 2505 2506
 out_free_vma:
	kmem_cache_free(vm_area_cachep, new);
 out_err:
	return err;
L
Linus Torvalds 已提交
2507 2508
}

2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521
/*
 * 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
2522 2523 2524 2525 2526 2527 2528 2529
/* 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;
2530
	struct vm_area_struct *vma, *prev, *last;
L
Linus Torvalds 已提交
2531 2532 2533 2534

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

V
vishnu.ps 已提交
2535 2536
	len = PAGE_ALIGN(len);
	if (len == 0)
L
Linus Torvalds 已提交
2537 2538 2539
		return -EINVAL;

	/* Find the first overlapping VMA */
2540
	vma = find_vma(mm, start);
2541
	if (!vma)
L
Linus Torvalds 已提交
2542
		return 0;
2543
	prev = vma->vm_prev;
2544
	/* we have  start < vma->vm_end  */
L
Linus Torvalds 已提交
2545 2546 2547

	/* if it doesn't overlap, we have nothing.. */
	end = start + len;
2548
	if (vma->vm_start >= end)
L
Linus Torvalds 已提交
2549 2550 2551 2552 2553 2554 2555 2556 2557
		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.
	 */
2558
	if (start > vma->vm_start) {
2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569
		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
2570 2571
		if (error)
			return error;
2572
		prev = vma;
L
Linus Torvalds 已提交
2573 2574 2575 2576 2577
	}

	/* Does it split the last one? */
	last = find_vma(mm, end);
	if (last && end > last->vm_start) {
2578
		int error = __split_vma(mm, last, end, 1);
L
Linus Torvalds 已提交
2579 2580 2581
		if (error)
			return error;
	}
V
vishnu.ps 已提交
2582
	vma = prev ? prev->vm_next : mm->mmap;
L
Linus Torvalds 已提交
2583

2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597
	/*
	 * 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
2598 2599 2600
	/*
	 * Remove the vma's, and unmap the actual pages
	 */
2601 2602
	detach_vmas_to_be_unmapped(mm, vma, prev, end);
	unmap_region(mm, vma, prev, start, end);
L
Linus Torvalds 已提交
2603

2604 2605
	arch_unmap(mm, vma, start, end);

L
Linus Torvalds 已提交
2606
	/* Fix up all other VM information */
2607
	remove_vma_list(mm, vma);
L
Linus Torvalds 已提交
2608 2609 2610 2611

	return 0;
}

A
Al Viro 已提交
2612
int vm_munmap(unsigned long start, size_t len)
L
Linus Torvalds 已提交
2613 2614
{
	int ret;
A
Al Viro 已提交
2615
	struct mm_struct *mm = current->mm;
L
Linus Torvalds 已提交
2616 2617

	down_write(&mm->mmap_sem);
2618
	ret = do_munmap(mm, start, len);
L
Linus Torvalds 已提交
2619 2620 2621
	up_write(&mm->mmap_sem);
	return ret;
}
2622 2623 2624 2625 2626
EXPORT_SYMBOL(vm_munmap);

SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
{
	profile_munmap(addr);
A
Al Viro 已提交
2627
	return vm_munmap(addr, len);
2628
}
L
Linus Torvalds 已提交
2629 2630 2631

static inline void verify_mm_writelocked(struct mm_struct *mm)
{
2632
#ifdef CONFIG_DEBUG_VM
L
Linus Torvalds 已提交
2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644
	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.
 */
2645
static unsigned long do_brk(unsigned long addr, unsigned long len)
L
Linus Torvalds 已提交
2646
{
V
vishnu.ps 已提交
2647 2648
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma, *prev;
L
Linus Torvalds 已提交
2649
	unsigned long flags;
V
vishnu.ps 已提交
2650
	struct rb_node **rb_link, *rb_parent;
L
Linus Torvalds 已提交
2651
	pgoff_t pgoff = addr >> PAGE_SHIFT;
2652
	int error;
L
Linus Torvalds 已提交
2653 2654 2655 2656 2657

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

2658 2659
	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

A
Al Viro 已提交
2660 2661
	error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
	if (error & ~PAGE_MASK)
2662 2663
		return error;

2664 2665 2666
	error = mlock_future_check(mm, mm->def_flags, len);
	if (error)
		return error;
L
Linus Torvalds 已提交
2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677

	/*
	 * 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:
2678
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
L
Linus Torvalds 已提交
2679 2680 2681 2682 2683 2684
		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
2685
	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2686 2687 2688 2689 2690
		return -ENOMEM;

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

2691
	if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2692 2693 2694
		return -ENOMEM;

	/* Can we just expand an old private anonymous mapping? */
2695 2696 2697
	vma = vma_merge(mm, prev, addr, addr + len, flags,
					NULL, NULL, pgoff, NULL);
	if (vma)
L
Linus Torvalds 已提交
2698 2699 2700 2701 2702
		goto out;

	/*
	 * create a vma struct for an anonymous mapping
	 */
P
Pekka Enberg 已提交
2703
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2704 2705 2706 2707 2708
	if (!vma) {
		vm_unacct_memory(len >> PAGE_SHIFT);
		return -ENOMEM;
	}

2709
	INIT_LIST_HEAD(&vma->anon_vma_chain);
L
Linus Torvalds 已提交
2710 2711 2712 2713 2714
	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;
	vma->vm_pgoff = pgoff;
	vma->vm_flags = flags;
2715
	vma->vm_page_prot = vm_get_page_prot(flags);
L
Linus Torvalds 已提交
2716 2717
	vma_link(mm, vma, prev, rb_link, rb_parent);
out:
2718
	perf_event_mmap(vma);
L
Linus Torvalds 已提交
2719
	mm->total_vm += len >> PAGE_SHIFT;
2720 2721
	if (flags & VM_LOCKED)
		mm->locked_vm += (len >> PAGE_SHIFT);
2722
	vma->vm_flags |= VM_SOFTDIRTY;
L
Linus Torvalds 已提交
2723 2724 2725
	return addr;
}

2726 2727 2728 2729
unsigned long vm_brk(unsigned long addr, unsigned long len)
{
	struct mm_struct *mm = current->mm;
	unsigned long ret;
2730
	bool populate;
2731 2732 2733

	down_write(&mm->mmap_sem);
	ret = do_brk(addr, len);
2734
	populate = ((mm->def_flags & VM_LOCKED) != 0);
2735
	up_write(&mm->mmap_sem);
2736 2737
	if (populate)
		mm_populate(addr, len);
2738 2739 2740
	return ret;
}
EXPORT_SYMBOL(vm_brk);
L
Linus Torvalds 已提交
2741 2742 2743 2744

/* Release all mmaps. */
void exit_mmap(struct mm_struct *mm)
{
P
Peter Zijlstra 已提交
2745
	struct mmu_gather tlb;
2746
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2747 2748
	unsigned long nr_accounted = 0;

2749
	/* mm's last user has gone, and its about to be pulled down */
A
Andrea Arcangeli 已提交
2750
	mmu_notifier_release(mm);
2751

2752 2753 2754 2755 2756 2757 2758 2759
	if (mm->locked_vm) {
		vma = mm->mmap;
		while (vma) {
			if (vma->vm_flags & VM_LOCKED)
				munlock_vma_pages_all(vma);
			vma = vma->vm_next;
		}
	}
2760 2761 2762

	arch_exit_mmap(mm);

2763
	vma = mm->mmap;
2764 2765 2766
	if (!vma)	/* Can happen if dup_mmap() received an OOM */
		return;

L
Linus Torvalds 已提交
2767 2768
	lru_add_drain();
	flush_cache_mm(mm);
2769
	tlb_gather_mmu(&tlb, mm, 0, -1);
2770
	/* update_hiwater_rss(mm) here? but nobody should be looking */
2771
	/* Use -1 here to ensure all VMAs in the mm are unmapped */
2772
	unmap_vmas(&tlb, vma, 0, -1);
H
Hugh Dickins 已提交
2773

2774
	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2775
	tlb_finish_mmu(&tlb, 0, -1);
L
Linus Torvalds 已提交
2776 2777

	/*
2778 2779
	 * Walk the list again, actually closing and freeing it,
	 * with preemption enabled, without holding any MM locks.
L
Linus Torvalds 已提交
2780
	 */
2781 2782 2783
	while (vma) {
		if (vma->vm_flags & VM_ACCOUNT)
			nr_accounted += vma_pages(vma);
2784
		vma = remove_vma(vma);
2785 2786
	}
	vm_unacct_memory(nr_accounted);
2787

2788 2789
	WARN_ON(atomic_long_read(&mm->nr_ptes) >
			(FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
L
Linus Torvalds 已提交
2790 2791 2792 2793
}

/* Insert vm structure into process list sorted by address
 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2794
 * then i_mmap_mutex is taken here.
L
Linus Torvalds 已提交
2795
 */
2796
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
2797
{
2798 2799
	struct vm_area_struct *prev;
	struct rb_node **rb_link, *rb_parent;
L
Linus Torvalds 已提交
2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816

	/*
	 * 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;
	}
2817 2818
	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
			   &prev, &rb_link, &rb_parent))
L
Linus Torvalds 已提交
2819
		return -ENOMEM;
2820
	if ((vma->vm_flags & VM_ACCOUNT) &&
2821
	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
2822
		return -ENOMEM;
2823

L
Linus Torvalds 已提交
2824 2825 2826 2827 2828 2829 2830 2831 2832
	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,
2833 2834
	unsigned long addr, unsigned long len, pgoff_t pgoff,
	bool *need_rmap_locks)
L
Linus Torvalds 已提交
2835 2836 2837 2838 2839 2840
{
	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;
2841
	bool faulted_in_anon_vma = true;
L
Linus Torvalds 已提交
2842 2843 2844 2845 2846

	/*
	 * If anonymous vma has not yet been faulted, update new pgoff
	 * to match new location, to increase its chance of merging.
	 */
2847
	if (unlikely(!vma->vm_file && !vma->anon_vma)) {
L
Linus Torvalds 已提交
2848
		pgoff = addr >> PAGE_SHIFT;
2849 2850
		faulted_in_anon_vma = false;
	}
L
Linus Torvalds 已提交
2851

2852 2853
	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
2854 2855 2856 2857 2858 2859
	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
		 */
2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873
		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.
			 */
2874
			VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2875
			*vmap = vma = new_vma;
2876
		}
2877
		*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
L
Linus Torvalds 已提交
2878
	} else {
2879
		new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2880 2881
		if (new_vma) {
			*new_vma = *vma;
2882 2883 2884
			new_vma->vm_start = addr;
			new_vma->vm_end = addr + len;
			new_vma->vm_pgoff = pgoff;
2885
			if (vma_dup_policy(vma, new_vma))
2886 2887 2888 2889
				goto out_free_vma;
			INIT_LIST_HEAD(&new_vma->anon_vma_chain);
			if (anon_vma_clone(new_vma, vma))
				goto out_free_mempol;
2890
			if (new_vma->vm_file)
L
Linus Torvalds 已提交
2891 2892 2893 2894
				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);
2895
			*need_rmap_locks = false;
L
Linus Torvalds 已提交
2896 2897 2898
		}
	}
	return new_vma;
2899 2900

 out_free_mempol:
2901
	mpol_put(vma_policy(new_vma));
2902 2903 2904
 out_free_vma:
	kmem_cache_free(vm_area_cachep, new_vma);
	return NULL;
L
Linus Torvalds 已提交
2905
}
A
akpm@osdl.org 已提交
2906 2907 2908 2909 2910 2911 2912 2913 2914 2915

/*
 * 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
2916
	lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
A
akpm@osdl.org 已提交
2917 2918 2919 2920 2921

	if (cur + npages > lim)
		return 0;
	return 1;
}
2922

2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947
static int special_mapping_fault(struct vm_area_struct *vma,
				 struct vm_fault *vmf);

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

static const char *special_mapping_name(struct vm_area_struct *vma)
{
	return ((struct vm_special_mapping *)vma->vm_private_data)->name;
}

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

static const struct vm_operations_struct legacy_special_mapping_vmops = {
	.close = special_mapping_close,
	.fault = special_mapping_fault,
};
2948

N
Nick Piggin 已提交
2949 2950
static int special_mapping_fault(struct vm_area_struct *vma,
				struct vm_fault *vmf)
2951
{
N
Nick Piggin 已提交
2952
	pgoff_t pgoff;
2953 2954
	struct page **pages;

N
Nick Piggin 已提交
2955 2956 2957 2958 2959 2960 2961
	/*
	 * 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;
2962

2963 2964 2965 2966 2967 2968 2969
	if (vma->vm_ops == &legacy_special_mapping_vmops)
		pages = vma->vm_private_data;
	else
		pages = ((struct vm_special_mapping *)vma->vm_private_data)->
			pages;

	for (; pgoff && *pages; ++pages)
N
Nick Piggin 已提交
2970
		pgoff--;
2971 2972 2973 2974

	if (*pages) {
		struct page *page = *pages;
		get_page(page);
N
Nick Piggin 已提交
2975 2976
		vmf->page = page;
		return 0;
2977 2978
	}

N
Nick Piggin 已提交
2979
	return VM_FAULT_SIGBUS;
2980 2981
}

2982 2983 2984 2985 2986
static struct vm_area_struct *__install_special_mapping(
	struct mm_struct *mm,
	unsigned long addr, unsigned long len,
	unsigned long vm_flags, const struct vm_operations_struct *ops,
	void *priv)
2987
{
2988
	int ret;
2989 2990 2991 2992
	struct vm_area_struct *vma;

	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (unlikely(vma == NULL))
2993
		return ERR_PTR(-ENOMEM);
2994

2995
	INIT_LIST_HEAD(&vma->anon_vma_chain);
2996 2997 2998 2999
	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;

3000
	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3001
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3002

3003 3004
	vma->vm_ops = ops;
	vma->vm_private_data = priv;
3005

3006 3007 3008
	ret = insert_vm_struct(mm, vma);
	if (ret)
		goto out;
3009 3010 3011

	mm->total_vm += len >> PAGE_SHIFT;

3012
	perf_event_mmap(vma);
3013

3014
	return vma;
3015 3016 3017

out:
	kmem_cache_free(vm_area_cachep, vma);
3018 3019 3020
	return ERR_PTR(ret);
}

3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038
/*
 * 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.
 */
struct vm_area_struct *_install_special_mapping(
	struct mm_struct *mm,
	unsigned long addr, unsigned long len,
	unsigned long vm_flags, const struct vm_special_mapping *spec)
{
	return __install_special_mapping(mm, addr, len, vm_flags,
					 &special_mapping_vmops, (void *)spec);
}

3039 3040 3041 3042
int install_special_mapping(struct mm_struct *mm,
			    unsigned long addr, unsigned long len,
			    unsigned long vm_flags, struct page **pages)
{
3043 3044 3045
	struct vm_area_struct *vma = __install_special_mapping(
		mm, addr, len, vm_flags, &legacy_special_mapping_vmops,
		(void *)pages);
3046

3047
	return PTR_ERR_OR_ZERO(vma);
3048
}
3049 3050 3051

static DEFINE_MUTEX(mm_all_locks_mutex);

3052
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3053
{
3054
	if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3055 3056 3057 3058
		/*
		 * The LSB of head.next can't change from under us
		 * because we hold the mm_all_locks_mutex.
		 */
3059
		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3060 3061
		/*
		 * We can safely modify head.next after taking the
3062
		 * anon_vma->root->rwsem. If some other vma in this mm shares
3063 3064 3065 3066
		 * 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
3067
		 * anon_vma->root->rwsem.
3068 3069
		 */
		if (__test_and_set_bit(0, (unsigned long *)
3070
				       &anon_vma->root->rb_root.rb_node))
3071 3072 3073 3074
			BUG();
	}
}

3075
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088
{
	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();
3089
		mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110
	}
}

/*
 * 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.
 *
3111
 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3112 3113 3114 3115
 * 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
3116
 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127
 * 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;
3128
	struct anon_vma_chain *avc;
3129 3130 3131 3132 3133 3134 3135 3136 3137

	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)
3138
			vm_lock_mapping(mm, vma->vm_file->f_mapping);
3139
	}
3140 3141 3142 3143 3144

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (signal_pending(current))
			goto out_unlock;
		if (vma->anon_vma)
3145 3146
			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
				vm_lock_anon_vma(mm, avc->anon_vma);
3147
	}
3148

3149
	return 0;
3150 3151

out_unlock:
3152 3153
	mm_drop_all_locks(mm);
	return -EINTR;
3154 3155 3156 3157
}

static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
{
3158
	if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3159 3160 3161 3162 3163
		/*
		 * 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
3164
		 * the vma so the users using the anon_vma->rb_root will
3165 3166 3167 3168
		 * never see our bitflag.
		 *
		 * No need of atomic instructions here, head.next
		 * can't change from under us until we release the
3169
		 * anon_vma->root->rwsem.
3170 3171
		 */
		if (!__test_and_clear_bit(0, (unsigned long *)
3172
					  &anon_vma->root->rb_root.rb_node))
3173
			BUG();
3174
		anon_vma_unlock_write(anon_vma);
3175 3176 3177 3178 3179 3180 3181 3182 3183 3184
	}
}

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.
		 */
3185
		i_mmap_unlock_write(mapping);
3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198
		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;
3199
	struct anon_vma_chain *avc;
3200 3201 3202 3203 3204 3205

	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)
3206 3207
			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
				vm_unlock_anon_vma(avc->anon_vma);
3208 3209 3210 3211 3212 3213
		if (vma->vm_file && vma->vm_file->f_mapping)
			vm_unlock_mapping(vma->vm_file->f_mapping);
	}

	mutex_unlock(&mm_all_locks_mutex);
}
3214 3215 3216 3217 3218 3219

/*
 * initialise the VMA slab
 */
void __init mmap_init(void)
{
3220 3221
	int ret;

3222
	ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3223
	VM_BUG_ON(ret);
3224
}
3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235

/*
 * 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.
 */
3236
static int init_user_reserve(void)
3237 3238 3239 3240 3241 3242 3243 3244
{
	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;
}
3245
subsys_initcall(init_user_reserve);
3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256

/*
 * 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.
 */
3257
static int init_admin_reserve(void)
3258 3259 3260 3261 3262 3263 3264 3265
{
	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;
}
3266
subsys_initcall(init_admin_reserve);
3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331

/*
 * 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))
3332
		pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3333 3334 3335

	return 0;
}
3336
subsys_initcall(init_reserve_notifier);