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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		mutex_lock(&mapping->i_mmap_mutex);
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		__remove_shared_vm_struct(vma, file, mapping);
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		mutex_unlock(&mapping->i_mmap_mutex);
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	}
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}

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

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

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

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SYSCALL_DEFINE1(brk, unsigned long, brk)
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{
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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);
}

552 553 554
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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}

586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613
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);
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	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)
649
			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
		mutex_lock(&mapping->i_mmap_mutex);
678
	}
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	__vma_link(mm, vma, prev, rb_link, rb_parent);
	__vma_link_file(vma);

	if (mapping)
684
		mutex_unlock(&mapping->i_mmap_mutex);
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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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699 700 701
	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) {
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		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);
769
			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.
		 */
778 779
		if (exporter && exporter->anon_vma && !importer->anon_vma) {
			if (anon_vma_clone(importer, exporter))
780
				return -ENOMEM;
781
			importer->anon_vma = exporter->anon_vma;
782 783 784
		}
	}

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	if (file) {
		mapping = file->f_mapping;
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		if (!(vma->vm_flags & VM_NONLINEAR)) {
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			root = &mapping->i_mmap;
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			uprobe_munmap(vma, vma->vm_start, vma->vm_end);
790 791

			if (adjust_next)
792 793
				uprobe_munmap(next, next->vm_start,
							next->vm_end);
794 795
		}

796
		mutex_lock(&mapping->i_mmap_mutex);
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		if (insert) {
			/*
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			 * 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);
		}
	}

808 809
	vma_adjust_trans_huge(vma, start, end, adjust_next);

810 811 812 813
	anon_vma = vma->anon_vma;
	if (!anon_vma && adjust_next)
		anon_vma = next->anon_vma;
	if (anon_vma) {
814 815
		VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
			  anon_vma != next->anon_vma, next);
816
		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)
826
			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)
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			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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	}

876 877 878 879
	if (anon_vma) {
		anon_vma_interval_tree_post_update_vma(vma);
		if (adjust_next)
			anon_vma_interval_tree_post_update_vma(next);
880
		anon_vma_unlock_write(anon_vma);
881
	}
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	if (mapping)
883
		mutex_unlock(&mapping->i_mmap_mutex);
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885
	if (root) {
886
		uprobe_mmap(vma);
887 888

		if (adjust_next)
889
			uprobe_mmap(next);
890 891
	}

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	if (remove_next) {
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		if (file) {
894
			uprobe_munmap(next, next->vm_start, next->vm_end);
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			fput(file);
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		}
897 898
		if (next->anon_vma)
			anon_vma_merge(vma, next);
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		mm->map_count--;
900
		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.
		 */
907 908
		next = vma->vm_next;
		if (remove_next == 2)
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			goto again;
910 911 912 913
		else if (next)
			vma_gap_update(next);
		else
			mm->highest_vm_end = end;
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	}
915
	if (insert && file)
916
		uprobe_mmap(insert);
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	validate_mm(mm);
919 920

	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)
{
930 931 932 933 934 935 936 937 938
	/*
	 * 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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	    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) &&
S
Shaohua Li 已提交
996
	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
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		pgoff_t vm_pglen;
998
		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;
1042
	int err;
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1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062

	/*
	 * 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
1063
			mpol_equal(vma_policy(prev), policy) &&
L
Linus Torvalds 已提交
1064 1065 1066 1067 1068 1069 1070 1071 1072 1073
			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
1074
						      next->anon_vma, NULL)) {
L
Linus Torvalds 已提交
1075
							/* cases 1, 6 */
1076
			err = vma_adjust(prev, prev->vm_start,
L
Linus Torvalds 已提交
1077 1078
				next->vm_end, prev->vm_pgoff, NULL);
		} else					/* cases 2, 5, 7 */
1079
			err = vma_adjust(prev, prev->vm_start,
L
Linus Torvalds 已提交
1080
				end, prev->vm_pgoff, NULL);
1081 1082
		if (err)
			return NULL;
1083
		khugepaged_enter_vma_merge(prev, vm_flags);
L
Linus Torvalds 已提交
1084 1085 1086 1087 1088 1089 1090
		return prev;
	}

	/*
	 * Can this new request be merged in front of next?
	 */
	if (next && end == next->vm_start &&
V
vishnu.ps 已提交
1091
			mpol_equal(policy, vma_policy(next)) &&
L
Linus Torvalds 已提交
1092 1093 1094
			can_vma_merge_before(next, vm_flags,
					anon_vma, file, pgoff+pglen)) {
		if (prev && addr < prev->vm_end)	/* case 4 */
1095
			err = vma_adjust(prev, prev->vm_start,
L
Linus Torvalds 已提交
1096 1097
				addr, prev->vm_pgoff, NULL);
		else					/* cases 3, 8 */
1098
			err = vma_adjust(area, addr, next->vm_end,
L
Linus Torvalds 已提交
1099
				next->vm_pgoff - pglen, NULL);
1100 1101
		if (err)
			return NULL;
1102
		khugepaged_enter_vma_merge(area, vm_flags);
L
Linus Torvalds 已提交
1103 1104 1105 1106 1107 1108
		return area;
	}

	return NULL;
}

1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126
/*
 * 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 &&
1127
		!((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1128 1129 1130 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
		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
1164 1165 1166 1167 1168 1169 1170 1171 1172 1173
/*
 * 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)
{
1174
	struct anon_vma *anon_vma;
L
Linus Torvalds 已提交
1175 1176 1177 1178 1179 1180
	struct vm_area_struct *near;

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

1181 1182 1183
	anon_vma = reusable_anon_vma(near, vma, near);
	if (anon_vma)
		return anon_vma;
L
Linus Torvalds 已提交
1184
try_prev:
1185
	near = vma->vm_prev;
L
Linus Torvalds 已提交
1186 1187 1188
	if (!near)
		goto none;

1189 1190 1191
	anon_vma = reusable_anon_vma(near, near, vma);
	if (anon_vma)
		return anon_vma;
L
Linus Torvalds 已提交
1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204
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
1205
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
L
Linus Torvalds 已提交
1206 1207 1208 1209 1210
						struct file *file, long pages)
{
	const unsigned long stack_flags
		= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);

1211 1212
	mm->total_vm += pages;

L
Linus Torvalds 已提交
1213 1214 1215 1216 1217 1218 1219 1220 1221
	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
1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234
/*
 * 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;
}

1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252
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
1253
/*
1254
 * The caller must hold down_write(&current->mm->mmap_sem).
L
Linus Torvalds 已提交
1255 1256
 */

1257
unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
L
Linus Torvalds 已提交
1258
			unsigned long len, unsigned long prot,
1259
			unsigned long flags, unsigned long pgoff,
1260
			unsigned long *populate)
L
Linus Torvalds 已提交
1261
{
V
vishnu.ps 已提交
1262
	struct mm_struct *mm = current->mm;
1263
	vm_flags_t vm_flags;
L
Linus Torvalds 已提交
1264

1265
	*populate = 0;
1266

L
Linus Torvalds 已提交
1267 1268 1269 1270 1271 1272 1273
	/*
	 * 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))
1274
		if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
L
Linus Torvalds 已提交
1275 1276 1277 1278 1279
			prot |= PROT_EXEC;

	if (!len)
		return -EINVAL;

1280 1281 1282
	if (!(flags & MAP_FIXED))
		addr = round_hint_to_min(addr);

L
Linus Torvalds 已提交
1283 1284
	/* Careful about overflows.. */
	len = PAGE_ALIGN(len);
1285
	if (!len)
L
Linus Torvalds 已提交
1286 1287 1288 1289
		return -ENOMEM;

	/* offset overflow? */
	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
V
vishnu.ps 已提交
1290
		return -EOVERFLOW;
L
Linus Torvalds 已提交
1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309

	/* 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
1310
	if (flags & MAP_LOCKED)
L
Linus Torvalds 已提交
1311 1312
		if (!can_do_mlock())
			return -EPERM;
1313

1314 1315
	if (mlock_future_check(mm, vm_flags, len))
		return -EAGAIN;
L
Linus Torvalds 已提交
1316 1317

	if (file) {
1318 1319
		struct inode *inode = file_inode(file);

L
Linus Torvalds 已提交
1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334
		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.
			 */
1335
			if (locks_verify_locked(file))
L
Linus Torvalds 已提交
1336 1337 1338 1339 1340 1341 1342 1343 1344 1345
				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;
1346
			if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
L
Linus Torvalds 已提交
1347 1348 1349 1350 1351
				if (vm_flags & VM_EXEC)
					return -EPERM;
				vm_flags &= ~VM_MAYEXEC;
			}

A
Al Viro 已提交
1352
			if (!file->f_op->mmap)
L
Linus Torvalds 已提交
1353
				return -ENODEV;
1354 1355
			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
				return -EINVAL;
L
Linus Torvalds 已提交
1356 1357 1358 1359 1360 1361 1362 1363
			break;

		default:
			return -EINVAL;
		}
	} else {
		switch (flags & MAP_TYPE) {
		case MAP_SHARED:
1364 1365
			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
				return -EINVAL;
1366 1367 1368 1369
			/*
			 * Ignore pgoff.
			 */
			pgoff = 0;
L
Linus Torvalds 已提交
1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382
			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;
		}
	}

1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397
	/*
	 * 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);
1398 1399 1400
	if (!IS_ERR_VALUE(addr) &&
	    ((vm_flags & VM_LOCKED) ||
	     (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1401
		*populate = len;
1402
	return addr;
M
Miklos Szeredi 已提交
1403
}
1404

H
Hugh Dickins 已提交
1405 1406 1407 1408 1409 1410 1411 1412
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
1413
		audit_mmap_fd(fd, flags);
H
Hugh Dickins 已提交
1414 1415 1416
		file = fget(fd);
		if (!file)
			goto out;
1417 1418
		if (is_file_hugepages(file))
			len = ALIGN(len, huge_page_size(hstate_file(file)));
1419 1420 1421
		retval = -EINVAL;
		if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
			goto out_fput;
H
Hugh Dickins 已提交
1422 1423
	} else if (flags & MAP_HUGETLB) {
		struct user_struct *user = NULL;
1424
		struct hstate *hs;
1425

1426
		hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1427 1428 1429 1430
		if (!hs)
			return -EINVAL;

		len = ALIGN(len, huge_page_size(hs));
H
Hugh Dickins 已提交
1431 1432 1433 1434 1435 1436
		/*
		 * 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
		 */
1437
		file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1438 1439 1440
				VM_NORESERVE,
				&user, HUGETLB_ANONHUGE_INODE,
				(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
H
Hugh Dickins 已提交
1441 1442 1443 1444 1445 1446
		if (IS_ERR(file))
			return PTR_ERR(file);
	}

	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);

A
Al Viro 已提交
1447
	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1448
out_fput:
H
Hugh Dickins 已提交
1449 1450 1451 1452 1453 1454
	if (file)
		fput(file);
out:
	return retval;
}

C
Christoph Hellwig 已提交
1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478
#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
1479 1480 1481 1482 1483 1484 1485 1486
/*
 * 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)
{
1487
	vm_flags_t vm_flags = vma->vm_flags;
A
Alexey Dobriyan 已提交
1488 1489 1490 1491 1492 1493 1494 1495 1496

	/* 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;

1497 1498
	/* The open routine did something to the protections that pgprot_modify
	 * won't preserve? */
A
Alexey Dobriyan 已提交
1499
	if (pgprot_val(vma->vm_page_prot) !=
1500
	    pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
A
Alexey Dobriyan 已提交
1501 1502
		return 0;

1503 1504 1505 1506
	/* 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
1507
	/* Specialty mapping? */
1508
	if (vm_flags & VM_PFNMAP)
A
Alexey Dobriyan 已提交
1509 1510 1511 1512 1513 1514 1515
		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);
}

1516 1517
/*
 * We account for memory if it's a private writeable mapping,
1518
 * not hugepages and VM_NORESERVE wasn't set.
1519
 */
1520
static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1521
{
1522 1523 1524 1525 1526 1527 1528
	/*
	 * 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;

1529 1530 1531
	return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
}

M
Miklos Szeredi 已提交
1532
unsigned long mmap_region(struct file *file, unsigned long addr,
1533
		unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
M
Miklos Szeredi 已提交
1534 1535 1536 1537 1538 1539 1540
{
	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;

1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557
	/* 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
1558 1559 1560
	/* Clear old maps */
	error = -ENOMEM;
munmap_back:
1561
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
L
Linus Torvalds 已提交
1562 1563 1564 1565 1566
		if (do_munmap(mm, addr, len))
			return -ENOMEM;
		goto munmap_back;
	}

1567 1568 1569
	/*
	 * Private writable mapping: check memory availability
	 */
1570
	if (accountable_mapping(file, vm_flags)) {
1571
		charged = len >> PAGE_SHIFT;
1572
		if (security_vm_enough_memory_mm(mm, charged))
1573 1574
			return -ENOMEM;
		vm_flags |= VM_ACCOUNT;
L
Linus Torvalds 已提交
1575 1576 1577
	}

	/*
1578
	 * Can we just expand an old mapping?
L
Linus Torvalds 已提交
1579
	 */
1580 1581 1582
	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
	if (vma)
		goto out;
L
Linus Torvalds 已提交
1583 1584 1585 1586 1587 1588

	/*
	 * 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
1589
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
1590 1591 1592 1593 1594 1595 1596 1597 1598
	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;
1599
	vma->vm_page_prot = vm_get_page_prot(vm_flags);
L
Linus Torvalds 已提交
1600
	vma->vm_pgoff = pgoff;
1601
	INIT_LIST_HEAD(&vma->anon_vma_chain);
L
Linus Torvalds 已提交
1602 1603 1604 1605 1606 1607 1608

	if (file) {
		if (vm_flags & VM_DENYWRITE) {
			error = deny_write_access(file);
			if (error)
				goto free_vma;
		}
1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619
		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
1620
		vma->vm_file = get_file(file);
L
Linus Torvalds 已提交
1621 1622 1623
		error = file->f_op->mmap(file, vma);
		if (error)
			goto unmap_and_free_vma;
1624 1625 1626 1627 1628

		/* Can addr have changed??
		 *
		 * Answer: Yes, several device drivers can do it in their
		 *         f_op->mmap method. -DaveM
1629 1630
		 * Bug: If addr is changed, prev, rb_link, rb_parent should
		 *      be updated for vma_link()
1631
		 */
1632 1633
		WARN_ON_ONCE(addr != vma->vm_start);

1634 1635
		addr = vma->vm_start;
		vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
1636 1637 1638 1639 1640 1641
	} else if (vm_flags & VM_SHARED) {
		error = shmem_zero_setup(vma);
		if (error)
			goto free_vma;
	}

1642
	vma_link(mm, vma, prev, rb_link, rb_parent);
1643
	/* Once vma denies write, undo our temporary denial count */
1644 1645 1646 1647 1648 1649
	if (file) {
		if (vm_flags & VM_SHARED)
			mapping_unmap_writable(file->f_mapping);
		if (vm_flags & VM_DENYWRITE)
			allow_write_access(file);
	}
1650
	file = vma->vm_file;
1651
out:
1652
	perf_event_mmap(vma);
1653

1654
	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
L
Linus Torvalds 已提交
1655
	if (vm_flags & VM_LOCKED) {
1656 1657
		if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
					vma == get_gate_vma(current->mm)))
1658
			mm->locked_vm += (len >> PAGE_SHIFT);
1659 1660 1661
		else
			vma->vm_flags &= ~VM_LOCKED;
	}
1662

1663 1664
	if (file)
		uprobe_mmap(vma);
1665

1666 1667 1668 1669 1670 1671 1672 1673 1674
	/*
	 * 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;

1675 1676
	vma_set_page_prot(vma);

L
Linus Torvalds 已提交
1677 1678 1679 1680 1681 1682 1683
	return addr;

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

	/* Undo any partial mapping done by a device driver. */
1684 1685
	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
	charged = 0;
1686 1687 1688 1689 1690
	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
1691 1692 1693 1694 1695 1696 1697 1698
free_vma:
	kmem_cache_free(vm_area_cachep, vma);
unacct_error:
	if (charged)
		vm_unacct_memory(charged);
	return error;
}

1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 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
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
1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916
/* 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;
1917
	struct vm_unmapped_area_info info;
L
Linus Torvalds 已提交
1918

1919
	if (len > TASK_SIZE - mmap_min_addr)
L
Linus Torvalds 已提交
1920 1921
		return -ENOMEM;

1922 1923 1924
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1925 1926 1927
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
1928
		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
L
Linus Torvalds 已提交
1929 1930 1931 1932
		    (!vma || addr + len <= vma->vm_start))
			return addr;
	}

1933 1934
	info.flags = 0;
	info.length = len;
1935
	info.low_limit = mm->mmap_base;
1936 1937 1938
	info.high_limit = TASK_SIZE;
	info.align_mask = 0;
	return vm_unmapped_area(&info);
L
Linus Torvalds 已提交
1939
}
V
vishnu.ps 已提交
1940
#endif
L
Linus Torvalds 已提交
1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953

/*
 * 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;
1954 1955
	unsigned long addr = addr0;
	struct vm_unmapped_area_info info;
L
Linus Torvalds 已提交
1956 1957

	/* requested length too big for entire address space */
1958
	if (len > TASK_SIZE - mmap_min_addr)
L
Linus Torvalds 已提交
1959 1960
		return -ENOMEM;

1961 1962 1963
	if (flags & MAP_FIXED)
		return addr;

L
Linus Torvalds 已提交
1964 1965 1966 1967
	/* requesting a specific address */
	if (addr) {
		addr = PAGE_ALIGN(addr);
		vma = find_vma(mm, addr);
1968
		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
L
Linus Torvalds 已提交
1969 1970 1971 1972
				(!vma || addr + len <= vma->vm_start))
			return addr;
	}

1973 1974
	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
	info.length = len;
1975
	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1976 1977 1978
	info.high_limit = mm->mmap_base;
	info.align_mask = 0;
	addr = vm_unmapped_area(&info);
1979

L
Linus Torvalds 已提交
1980 1981 1982 1983 1984 1985
	/*
	 * 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.
	 */
1986 1987 1988 1989 1990 1991 1992
	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
1993 1994 1995 1996 1997 1998 1999 2000 2001

	return addr;
}
#endif

unsigned long
get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
		unsigned long pgoff, unsigned long flags)
{
2002 2003 2004
	unsigned long (*get_area)(struct file *, unsigned long,
				  unsigned long, unsigned long, unsigned long);

2005 2006 2007 2008 2009 2010 2011 2012
	unsigned long error = arch_mmap_check(addr, len, flags);
	if (error)
		return error;

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

2013
	get_area = current->mm->get_unmapped_area;
A
Al Viro 已提交
2014
	if (file && file->f_op->get_unmapped_area)
2015 2016 2017 2018
		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
2019

2020 2021 2022 2023
	if (addr > TASK_SIZE - len)
		return -ENOMEM;
	if (addr & ~PAGE_MASK)
		return -EINVAL;
2024

2025 2026 2027
	addr = arch_rebalance_pgtables(addr, len);
	error = security_mmap_addr(addr);
	return error ? error : addr;
L
Linus Torvalds 已提交
2028 2029 2030 2031 2032
}

EXPORT_SYMBOL(get_unmapped_area);

/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
Z
ZhenwenXu 已提交
2033
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
2034
{
D
Davidlohr Bueso 已提交
2035 2036
	struct rb_node *rb_node;
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2037

2038
	/* Check the cache first. */
D
Davidlohr Bueso 已提交
2039 2040 2041
	vma = vmacache_find(mm, addr);
	if (likely(vma))
		return vma;
2042

D
Davidlohr Bueso 已提交
2043 2044
	rb_node = mm->mm_rb.rb_node;
	vma = NULL;
2045

D
Davidlohr Bueso 已提交
2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057
	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
2058
	}
D
Davidlohr Bueso 已提交
2059 2060 2061

	if (vma)
		vmacache_update(addr, vma);
L
Linus Torvalds 已提交
2062 2063 2064 2065 2066
	return vma;
}

EXPORT_SYMBOL(find_vma);

K
KOSAKI Motohiro 已提交
2067 2068 2069
/*
 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
 */
L
Linus Torvalds 已提交
2070 2071 2072 2073
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
2074
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2075

K
KOSAKI Motohiro 已提交
2076
	vma = find_vma(mm, addr);
M
Mikulas Patocka 已提交
2077 2078 2079 2080 2081 2082 2083 2084 2085 2086
	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
2087
	return vma;
L
Linus Torvalds 已提交
2088 2089 2090 2091 2092 2093 2094
}

/*
 * 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
2095
static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
L
Linus Torvalds 已提交
2096 2097 2098
{
	struct mm_struct *mm = vma->vm_mm;
	struct rlimit *rlim = current->signal->rlim;
2099
	unsigned long new_start;
L
Linus Torvalds 已提交
2100 2101

	/* address space limit tests */
A
akpm@osdl.org 已提交
2102
	if (!may_expand_vm(mm, grow))
L
Linus Torvalds 已提交
2103 2104 2105
		return -ENOMEM;

	/* Stack limit test */
J
Jiri Slaby 已提交
2106
	if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
L
Linus Torvalds 已提交
2107 2108 2109 2110 2111 2112 2113
		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
2114 2115
		limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
		limit >>= PAGE_SHIFT;
L
Linus Torvalds 已提交
2116 2117 2118 2119
		if (locked > limit && !capable(CAP_IPC_LOCK))
			return -ENOMEM;
	}

2120 2121 2122 2123 2124 2125
	/* 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
2126 2127 2128 2129
	/*
	 * Overcommit..  This must be the final test, as it will
	 * update security statistics.
	 */
2130
	if (security_vm_enough_memory_mm(mm, grow))
L
Linus Torvalds 已提交
2131 2132 2133 2134 2135
		return -ENOMEM;

	/* Ok, everything looks good - let it rip */
	if (vma->vm_flags & VM_LOCKED)
		mm->locked_vm += grow;
2136
	vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
L
Linus Torvalds 已提交
2137 2138 2139
	return 0;
}

H
Hugh Dickins 已提交
2140
#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
L
Linus Torvalds 已提交
2141
/*
H
Hugh Dickins 已提交
2142 2143
 * 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
2144
 */
H
Hugh Dickins 已提交
2145
int expand_upwards(struct vm_area_struct *vma, unsigned long address)
L
Linus Torvalds 已提交
2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157
{
	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;
2158
	vma_lock_anon_vma(vma);
L
Linus Torvalds 已提交
2159 2160 2161 2162 2163

	/*
	 * 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.
2164
	 * Also guard against wrapping around to address 0.
L
Linus Torvalds 已提交
2165
	 */
2166 2167 2168
	if (address < PAGE_ALIGN(address+4))
		address = PAGE_ALIGN(address+4);
	else {
2169
		vma_unlock_anon_vma(vma);
2170 2171
		return -ENOMEM;
	}
L
Linus Torvalds 已提交
2172 2173 2174 2175 2176 2177 2178 2179 2180
	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;

2181 2182 2183 2184
		error = -ENOMEM;
		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
			error = acct_stack_growth(vma, size, grow);
			if (!error) {
2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196
				/*
				 * 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);
2197
				anon_vma_interval_tree_pre_update_vma(vma);
2198
				vma->vm_end = address;
2199
				anon_vma_interval_tree_post_update_vma(vma);
2200 2201 2202 2203
				if (vma->vm_next)
					vma_gap_update(vma->vm_next);
				else
					vma->vm_mm->highest_vm_end = address;
2204 2205
				spin_unlock(&vma->vm_mm->page_table_lock);

2206 2207
				perf_event_mmap(vma);
			}
2208
		}
L
Linus Torvalds 已提交
2209
	}
2210
	vma_unlock_anon_vma(vma);
2211
	khugepaged_enter_vma_merge(vma, vma->vm_flags);
2212
	validate_mm(vma->vm_mm);
L
Linus Torvalds 已提交
2213 2214
	return error;
}
H
Hugh Dickins 已提交
2215 2216
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */

L
Linus Torvalds 已提交
2217 2218 2219
/*
 * vma is the first one with address < vma->vm_start.  Have to extend vma.
 */
2220
int expand_downwards(struct vm_area_struct *vma,
2221
				   unsigned long address)
L
Linus Torvalds 已提交
2222 2223 2224 2225 2226 2227 2228 2229 2230
{
	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;
2231 2232

	address &= PAGE_MASK;
2233
	error = security_mmap_addr(address);
2234 2235 2236
	if (error)
		return error;

2237
	vma_lock_anon_vma(vma);
L
Linus Torvalds 已提交
2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251

	/*
	 * 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;

2252 2253 2254 2255
		error = -ENOMEM;
		if (grow <= vma->vm_pgoff) {
			error = acct_stack_growth(vma, size, grow);
			if (!error) {
2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267
				/*
				 * 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);
2268
				anon_vma_interval_tree_pre_update_vma(vma);
2269 2270
				vma->vm_start = address;
				vma->vm_pgoff -= grow;
2271
				anon_vma_interval_tree_post_update_vma(vma);
2272
				vma_gap_update(vma);
2273 2274
				spin_unlock(&vma->vm_mm->page_table_lock);

2275 2276
				perf_event_mmap(vma);
			}
L
Linus Torvalds 已提交
2277 2278
		}
	}
2279
	vma_unlock_anon_vma(vma);
2280
	khugepaged_enter_vma_merge(vma, vma->vm_flags);
2281
	validate_mm(vma->vm_mm);
L
Linus Torvalds 已提交
2282 2283 2284
	return error;
}

2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295
/*
 * 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.
 */
2296 2297 2298
#ifdef CONFIG_STACK_GROWSUP
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
2299 2300 2301 2302 2303 2304 2305 2306
	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;
	}
2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318
	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;
2319
	if (!prev || expand_stack(prev, addr))
2320
		return NULL;
2321 2322
	if (prev->vm_flags & VM_LOCKED)
		__mlock_vma_pages_range(prev, addr, prev->vm_end, NULL);
2323 2324 2325 2326 2327
	return prev;
}
#else
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
2328 2329 2330 2331 2332 2333 2334 2335
	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;
	}
2336 2337 2338
	return expand_downwards(vma, address);
}

L
Linus Torvalds 已提交
2339
struct vm_area_struct *
V
vishnu.ps 已提交
2340
find_extend_vma(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
2341
{
V
vishnu.ps 已提交
2342
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2343 2344 2345
	unsigned long start;

	addr &= PAGE_MASK;
V
vishnu.ps 已提交
2346
	vma = find_vma(mm, addr);
L
Linus Torvalds 已提交
2347 2348 2349 2350 2351 2352 2353 2354 2355
	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;
2356 2357
	if (vma->vm_flags & VM_LOCKED)
		__mlock_vma_pages_range(vma, addr, start, NULL);
L
Linus Torvalds 已提交
2358 2359 2360 2361 2362
	return vma;
}
#endif

/*
2363
 * Ok - we have the memory areas we should free on the vma list,
L
Linus Torvalds 已提交
2364
 * so release them, and do the vma updates.
2365 2366
 *
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
2367
 */
2368
static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
2369
{
2370 2371
	unsigned long nr_accounted = 0;

2372 2373
	/* Update high watermark before we lower total_vm */
	update_hiwater_vm(mm);
L
Linus Torvalds 已提交
2374
	do {
2375 2376
		long nrpages = vma_pages(vma);

2377 2378
		if (vma->vm_flags & VM_ACCOUNT)
			nr_accounted += nrpages;
2379
		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2380
		vma = remove_vma(vma);
2381
	} while (vma);
2382
	vm_unacct_memory(nr_accounted);
L
Linus Torvalds 已提交
2383 2384 2385 2386 2387 2388
	validate_mm(mm);
}

/*
 * Get rid of page table information in the indicated region.
 *
2389
 * Called with the mm semaphore held.
L
Linus Torvalds 已提交
2390 2391
 */
static void unmap_region(struct mm_struct *mm,
2392 2393
		struct vm_area_struct *vma, struct vm_area_struct *prev,
		unsigned long start, unsigned long end)
L
Linus Torvalds 已提交
2394
{
V
vishnu.ps 已提交
2395
	struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
P
Peter Zijlstra 已提交
2396
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
2397 2398

	lru_add_drain();
2399
	tlb_gather_mmu(&tlb, mm, start, end);
2400
	update_hiwater_rss(mm);
2401
	unmap_vmas(&tlb, vma, start, end);
P
Peter Zijlstra 已提交
2402
	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2403
				 next ? next->vm_start : USER_PGTABLES_CEILING);
P
Peter Zijlstra 已提交
2404
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418
}

/*
 * 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);
2419
	vma->vm_prev = NULL;
L
Linus Torvalds 已提交
2420
	do {
2421
		vma_rb_erase(vma, &mm->mm_rb);
L
Linus Torvalds 已提交
2422 2423 2424 2425 2426
		mm->map_count--;
		tail_vma = vma;
		vma = vma->vm_next;
	} while (vma && vma->vm_start < end);
	*insertion_point = vma;
2427
	if (vma) {
2428
		vma->vm_prev = prev;
2429 2430 2431
		vma_gap_update(vma);
	} else
		mm->highest_vm_end = prev ? prev->vm_end : 0;
L
Linus Torvalds 已提交
2432
	tail_vma->vm_next = NULL;
D
Davidlohr Bueso 已提交
2433 2434 2435

	/* Kill the cache */
	vmacache_invalidate(mm);
L
Linus Torvalds 已提交
2436 2437 2438
}

/*
2439 2440
 * __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
2441
 */
V
vishnu.ps 已提交
2442
static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2443 2444 2445
	      unsigned long addr, int new_below)
{
	struct vm_area_struct *new;
2446
	int err = -ENOMEM;
L
Linus Torvalds 已提交
2447

2448 2449
	if (is_vm_hugetlb_page(vma) && (addr &
					~(huge_page_mask(hstate_vma(vma)))))
L
Linus Torvalds 已提交
2450 2451
		return -EINVAL;

2452
	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2453
	if (!new)
2454
		goto out_err;
L
Linus Torvalds 已提交
2455 2456 2457 2458

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

2459 2460
	INIT_LIST_HEAD(&new->anon_vma_chain);

L
Linus Torvalds 已提交
2461 2462 2463 2464 2465 2466 2467
	if (new_below)
		new->vm_end = addr;
	else {
		new->vm_start = addr;
		new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
	}

2468 2469
	err = vma_dup_policy(vma, new);
	if (err)
2470
		goto out_free_vma;
L
Linus Torvalds 已提交
2471

2472 2473 2474
	if (anon_vma_clone(new, vma))
		goto out_free_mpol;

2475
	if (new->vm_file)
L
Linus Torvalds 已提交
2476 2477 2478 2479 2480 2481
		get_file(new->vm_file);

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

	if (new_below)
2482
		err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
L
Linus Torvalds 已提交
2483 2484
			((addr - new->vm_start) >> PAGE_SHIFT), new);
	else
2485
		err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
L
Linus Torvalds 已提交
2486

2487 2488 2489 2490 2491
	/* Success. */
	if (!err)
		return 0;

	/* Clean everything up if vma_adjust failed. */
2492 2493
	if (new->vm_ops && new->vm_ops->close)
		new->vm_ops->close(new);
2494
	if (new->vm_file)
2495
		fput(new->vm_file);
2496
	unlink_anon_vmas(new);
2497
 out_free_mpol:
2498
	mpol_put(vma_policy(new));
2499 2500 2501 2502
 out_free_vma:
	kmem_cache_free(vm_area_cachep, new);
 out_err:
	return err;
L
Linus Torvalds 已提交
2503 2504
}

2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517
/*
 * 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
2518 2519 2520 2521 2522 2523 2524 2525
/* 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;
2526
	struct vm_area_struct *vma, *prev, *last;
L
Linus Torvalds 已提交
2527 2528 2529 2530

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

V
vishnu.ps 已提交
2531 2532
	len = PAGE_ALIGN(len);
	if (len == 0)
L
Linus Torvalds 已提交
2533 2534 2535
		return -EINVAL;

	/* Find the first overlapping VMA */
2536
	vma = find_vma(mm, start);
2537
	if (!vma)
L
Linus Torvalds 已提交
2538
		return 0;
2539
	prev = vma->vm_prev;
2540
	/* we have  start < vma->vm_end  */
L
Linus Torvalds 已提交
2541 2542 2543

	/* if it doesn't overlap, we have nothing.. */
	end = start + len;
2544
	if (vma->vm_start >= end)
L
Linus Torvalds 已提交
2545 2546 2547 2548 2549 2550 2551 2552 2553
		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.
	 */
2554
	if (start > vma->vm_start) {
2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565
		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
2566 2567
		if (error)
			return error;
2568
		prev = vma;
L
Linus Torvalds 已提交
2569 2570 2571 2572 2573
	}

	/* Does it split the last one? */
	last = find_vma(mm, end);
	if (last && end > last->vm_start) {
2574
		int error = __split_vma(mm, last, end, 1);
L
Linus Torvalds 已提交
2575 2576 2577
		if (error)
			return error;
	}
V
vishnu.ps 已提交
2578
	vma = prev ? prev->vm_next : mm->mmap;
L
Linus Torvalds 已提交
2579

2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593
	/*
	 * 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
2594 2595 2596
	/*
	 * Remove the vma's, and unmap the actual pages
	 */
2597 2598
	detach_vmas_to_be_unmapped(mm, vma, prev, end);
	unmap_region(mm, vma, prev, start, end);
L
Linus Torvalds 已提交
2599 2600

	/* Fix up all other VM information */
2601
	remove_vma_list(mm, vma);
L
Linus Torvalds 已提交
2602 2603 2604 2605

	return 0;
}

A
Al Viro 已提交
2606
int vm_munmap(unsigned long start, size_t len)
L
Linus Torvalds 已提交
2607 2608
{
	int ret;
A
Al Viro 已提交
2609
	struct mm_struct *mm = current->mm;
L
Linus Torvalds 已提交
2610 2611

	down_write(&mm->mmap_sem);
2612
	ret = do_munmap(mm, start, len);
L
Linus Torvalds 已提交
2613 2614 2615
	up_write(&mm->mmap_sem);
	return ret;
}
2616 2617 2618 2619 2620
EXPORT_SYMBOL(vm_munmap);

SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
{
	profile_munmap(addr);
A
Al Viro 已提交
2621
	return vm_munmap(addr, len);
2622
}
L
Linus Torvalds 已提交
2623 2624 2625

static inline void verify_mm_writelocked(struct mm_struct *mm)
{
2626
#ifdef CONFIG_DEBUG_VM
L
Linus Torvalds 已提交
2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638
	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.
 */
2639
static unsigned long do_brk(unsigned long addr, unsigned long len)
L
Linus Torvalds 已提交
2640
{
V
vishnu.ps 已提交
2641 2642
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma, *prev;
L
Linus Torvalds 已提交
2643
	unsigned long flags;
V
vishnu.ps 已提交
2644
	struct rb_node **rb_link, *rb_parent;
L
Linus Torvalds 已提交
2645
	pgoff_t pgoff = addr >> PAGE_SHIFT;
2646
	int error;
L
Linus Torvalds 已提交
2647 2648 2649 2650 2651

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

2652 2653
	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;

A
Al Viro 已提交
2654 2655
	error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
	if (error & ~PAGE_MASK)
2656 2657
		return error;

2658 2659 2660
	error = mlock_future_check(mm, mm->def_flags, len);
	if (error)
		return error;
L
Linus Torvalds 已提交
2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671

	/*
	 * 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:
2672
	if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) {
L
Linus Torvalds 已提交
2673 2674 2675 2676 2677 2678
		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
2679
	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2680 2681 2682 2683 2684
		return -ENOMEM;

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

2685
	if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
L
Linus Torvalds 已提交
2686 2687 2688
		return -ENOMEM;

	/* Can we just expand an old private anonymous mapping? */
2689 2690 2691
	vma = vma_merge(mm, prev, addr, addr + len, flags,
					NULL, NULL, pgoff, NULL);
	if (vma)
L
Linus Torvalds 已提交
2692 2693 2694 2695 2696
		goto out;

	/*
	 * create a vma struct for an anonymous mapping
	 */
P
Pekka Enberg 已提交
2697
	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2698 2699 2700 2701 2702
	if (!vma) {
		vm_unacct_memory(len >> PAGE_SHIFT);
		return -ENOMEM;
	}

2703
	INIT_LIST_HEAD(&vma->anon_vma_chain);
L
Linus Torvalds 已提交
2704 2705 2706 2707 2708
	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;
	vma->vm_pgoff = pgoff;
	vma->vm_flags = flags;
2709
	vma->vm_page_prot = vm_get_page_prot(flags);
L
Linus Torvalds 已提交
2710 2711
	vma_link(mm, vma, prev, rb_link, rb_parent);
out:
2712
	perf_event_mmap(vma);
L
Linus Torvalds 已提交
2713
	mm->total_vm += len >> PAGE_SHIFT;
2714 2715
	if (flags & VM_LOCKED)
		mm->locked_vm += (len >> PAGE_SHIFT);
2716
	vma->vm_flags |= VM_SOFTDIRTY;
L
Linus Torvalds 已提交
2717 2718 2719
	return addr;
}

2720 2721 2722 2723
unsigned long vm_brk(unsigned long addr, unsigned long len)
{
	struct mm_struct *mm = current->mm;
	unsigned long ret;
2724
	bool populate;
2725 2726 2727

	down_write(&mm->mmap_sem);
	ret = do_brk(addr, len);
2728
	populate = ((mm->def_flags & VM_LOCKED) != 0);
2729
	up_write(&mm->mmap_sem);
2730 2731
	if (populate)
		mm_populate(addr, len);
2732 2733 2734
	return ret;
}
EXPORT_SYMBOL(vm_brk);
L
Linus Torvalds 已提交
2735 2736 2737 2738

/* Release all mmaps. */
void exit_mmap(struct mm_struct *mm)
{
P
Peter Zijlstra 已提交
2739
	struct mmu_gather tlb;
2740
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
2741 2742
	unsigned long nr_accounted = 0;

2743
	/* mm's last user has gone, and its about to be pulled down */
A
Andrea Arcangeli 已提交
2744
	mmu_notifier_release(mm);
2745

2746 2747 2748 2749 2750 2751 2752 2753
	if (mm->locked_vm) {
		vma = mm->mmap;
		while (vma) {
			if (vma->vm_flags & VM_LOCKED)
				munlock_vma_pages_all(vma);
			vma = vma->vm_next;
		}
	}
2754 2755 2756

	arch_exit_mmap(mm);

2757
	vma = mm->mmap;
2758 2759 2760
	if (!vma)	/* Can happen if dup_mmap() received an OOM */
		return;

L
Linus Torvalds 已提交
2761 2762
	lru_add_drain();
	flush_cache_mm(mm);
2763
	tlb_gather_mmu(&tlb, mm, 0, -1);
2764
	/* update_hiwater_rss(mm) here? but nobody should be looking */
2765
	/* Use -1 here to ensure all VMAs in the mm are unmapped */
2766
	unmap_vmas(&tlb, vma, 0, -1);
H
Hugh Dickins 已提交
2767

2768
	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2769
	tlb_finish_mmu(&tlb, 0, -1);
L
Linus Torvalds 已提交
2770 2771

	/*
2772 2773
	 * Walk the list again, actually closing and freeing it,
	 * with preemption enabled, without holding any MM locks.
L
Linus Torvalds 已提交
2774
	 */
2775 2776 2777
	while (vma) {
		if (vma->vm_flags & VM_ACCOUNT)
			nr_accounted += vma_pages(vma);
2778
		vma = remove_vma(vma);
2779 2780
	}
	vm_unacct_memory(nr_accounted);
2781

2782 2783
	WARN_ON(atomic_long_read(&mm->nr_ptes) >
			(FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
L
Linus Torvalds 已提交
2784 2785 2786 2787
}

/* Insert vm structure into process list sorted by address
 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2788
 * then i_mmap_mutex is taken here.
L
Linus Torvalds 已提交
2789
 */
2790
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
2791
{
2792 2793
	struct vm_area_struct *prev;
	struct rb_node **rb_link, *rb_parent;
L
Linus Torvalds 已提交
2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810

	/*
	 * 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;
	}
2811 2812
	if (find_vma_links(mm, vma->vm_start, vma->vm_end,
			   &prev, &rb_link, &rb_parent))
L
Linus Torvalds 已提交
2813
		return -ENOMEM;
2814
	if ((vma->vm_flags & VM_ACCOUNT) &&
2815
	     security_vm_enough_memory_mm(mm, vma_pages(vma)))
2816
		return -ENOMEM;
2817

L
Linus Torvalds 已提交
2818 2819 2820 2821 2822 2823 2824 2825 2826
	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,
2827 2828
	unsigned long addr, unsigned long len, pgoff_t pgoff,
	bool *need_rmap_locks)
L
Linus Torvalds 已提交
2829 2830 2831 2832 2833 2834
{
	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;
2835
	bool faulted_in_anon_vma = true;
L
Linus Torvalds 已提交
2836 2837 2838 2839 2840

	/*
	 * If anonymous vma has not yet been faulted, update new pgoff
	 * to match new location, to increase its chance of merging.
	 */
2841
	if (unlikely(!vma->vm_file && !vma->anon_vma)) {
L
Linus Torvalds 已提交
2842
		pgoff = addr >> PAGE_SHIFT;
2843 2844
		faulted_in_anon_vma = false;
	}
L
Linus Torvalds 已提交
2845

2846 2847
	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
2848 2849 2850 2851 2852 2853
	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
		 */
2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867
		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.
			 */
2868
			VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2869
			*vmap = vma = new_vma;
2870
		}
2871
		*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
L
Linus Torvalds 已提交
2872
	} else {
2873
		new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2874 2875
		if (new_vma) {
			*new_vma = *vma;
2876 2877 2878
			new_vma->vm_start = addr;
			new_vma->vm_end = addr + len;
			new_vma->vm_pgoff = pgoff;
2879
			if (vma_dup_policy(vma, new_vma))
2880 2881 2882 2883
				goto out_free_vma;
			INIT_LIST_HEAD(&new_vma->anon_vma_chain);
			if (anon_vma_clone(new_vma, vma))
				goto out_free_mempol;
2884
			if (new_vma->vm_file)
L
Linus Torvalds 已提交
2885 2886 2887 2888
				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);
2889
			*need_rmap_locks = false;
L
Linus Torvalds 已提交
2890 2891 2892
		}
	}
	return new_vma;
2893 2894

 out_free_mempol:
2895
	mpol_put(vma_policy(new_vma));
2896 2897 2898
 out_free_vma:
	kmem_cache_free(vm_area_cachep, new_vma);
	return NULL;
L
Linus Torvalds 已提交
2899
}
A
akpm@osdl.org 已提交
2900 2901 2902 2903 2904 2905 2906 2907 2908 2909

/*
 * 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
2910
	lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
A
akpm@osdl.org 已提交
2911 2912 2913 2914 2915

	if (cur + npages > lim)
		return 0;
	return 1;
}
2916

2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941
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,
};
2942

N
Nick Piggin 已提交
2943 2944
static int special_mapping_fault(struct vm_area_struct *vma,
				struct vm_fault *vmf)
2945
{
N
Nick Piggin 已提交
2946
	pgoff_t pgoff;
2947 2948
	struct page **pages;

N
Nick Piggin 已提交
2949 2950 2951 2952 2953 2954 2955
	/*
	 * 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;
2956

2957 2958 2959 2960 2961 2962 2963
	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
2964
		pgoff--;
2965 2966 2967 2968

	if (*pages) {
		struct page *page = *pages;
		get_page(page);
N
Nick Piggin 已提交
2969 2970
		vmf->page = page;
		return 0;
2971 2972
	}

N
Nick Piggin 已提交
2973
	return VM_FAULT_SIGBUS;
2974 2975
}

2976 2977 2978 2979 2980
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)
2981
{
2982
	int ret;
2983 2984 2985 2986
	struct vm_area_struct *vma;

	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (unlikely(vma == NULL))
2987
		return ERR_PTR(-ENOMEM);
2988

2989
	INIT_LIST_HEAD(&vma->anon_vma_chain);
2990 2991 2992 2993
	vma->vm_mm = mm;
	vma->vm_start = addr;
	vma->vm_end = addr + len;

2994
	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
2995
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2996

2997 2998
	vma->vm_ops = ops;
	vma->vm_private_data = priv;
2999

3000 3001 3002
	ret = insert_vm_struct(mm, vma);
	if (ret)
		goto out;
3003 3004 3005

	mm->total_vm += len >> PAGE_SHIFT;

3006
	perf_event_mmap(vma);
3007

3008
	return vma;
3009 3010 3011

out:
	kmem_cache_free(vm_area_cachep, vma);
3012 3013 3014
	return ERR_PTR(ret);
}

3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032
/*
 * 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);
}

3033 3034 3035 3036
int install_special_mapping(struct mm_struct *mm,
			    unsigned long addr, unsigned long len,
			    unsigned long vm_flags, struct page **pages)
{
3037 3038 3039
	struct vm_area_struct *vma = __install_special_mapping(
		mm, addr, len, vm_flags, &legacy_special_mapping_vmops,
		(void *)pages);
3040

3041
	return PTR_ERR_OR_ZERO(vma);
3042
}
3043 3044 3045

static DEFINE_MUTEX(mm_all_locks_mutex);

3046
static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3047
{
3048
	if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3049 3050 3051 3052
		/*
		 * The LSB of head.next can't change from under us
		 * because we hold the mm_all_locks_mutex.
		 */
3053
		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3054 3055
		/*
		 * We can safely modify head.next after taking the
3056
		 * anon_vma->root->rwsem. If some other vma in this mm shares
3057 3058 3059 3060
		 * 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
3061
		 * anon_vma->root->rwsem.
3062 3063
		 */
		if (__test_and_set_bit(0, (unsigned long *)
3064
				       &anon_vma->root->rb_root.rb_node))
3065 3066 3067 3068
			BUG();
	}
}

3069
static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082
{
	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();
3083
		mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104
	}
}

/*
 * 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.
 *
3105
 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3106 3107 3108 3109
 * 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
3110
 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121
 * 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;
3122
	struct anon_vma_chain *avc;
3123 3124 3125 3126 3127 3128 3129 3130 3131

	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)
3132
			vm_lock_mapping(mm, vma->vm_file->f_mapping);
3133
	}
3134 3135 3136 3137 3138

	for (vma = mm->mmap; vma; vma = vma->vm_next) {
		if (signal_pending(current))
			goto out_unlock;
		if (vma->anon_vma)
3139 3140
			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
				vm_lock_anon_vma(mm, avc->anon_vma);
3141
	}
3142

3143
	return 0;
3144 3145

out_unlock:
3146 3147
	mm_drop_all_locks(mm);
	return -EINTR;
3148 3149 3150 3151
}

static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
{
3152
	if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3153 3154 3155 3156 3157
		/*
		 * 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
3158
		 * the vma so the users using the anon_vma->rb_root will
3159 3160 3161 3162
		 * never see our bitflag.
		 *
		 * No need of atomic instructions here, head.next
		 * can't change from under us until we release the
3163
		 * anon_vma->root->rwsem.
3164 3165
		 */
		if (!__test_and_clear_bit(0, (unsigned long *)
3166
					  &anon_vma->root->rb_root.rb_node))
3167
			BUG();
3168
		anon_vma_unlock_write(anon_vma);
3169 3170 3171 3172 3173 3174 3175 3176 3177 3178
	}
}

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.
		 */
3179
		mutex_unlock(&mapping->i_mmap_mutex);
3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192
		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;
3193
	struct anon_vma_chain *avc;
3194 3195 3196 3197 3198 3199

	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)
3200 3201
			list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
				vm_unlock_anon_vma(avc->anon_vma);
3202 3203 3204 3205 3206 3207
		if (vma->vm_file && vma->vm_file->f_mapping)
			vm_unlock_mapping(vma->vm_file->f_mapping);
	}

	mutex_unlock(&mm_all_locks_mutex);
}
3208 3209 3210 3211 3212 3213

/*
 * initialise the VMA slab
 */
void __init mmap_init(void)
{
3214 3215
	int ret;

3216
	ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3217
	VM_BUG_ON(ret);
3218
}
3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229

/*
 * 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.
 */
3230
static int init_user_reserve(void)
3231 3232 3233 3234 3235 3236 3237 3238
{
	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;
}
3239
subsys_initcall(init_user_reserve);
3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250

/*
 * 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.
 */
3251
static int init_admin_reserve(void)
3252 3253 3254 3255 3256 3257 3258 3259
{
	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;
}
3260
subsys_initcall(init_admin_reserve);
3261 3262 3263 3264 3265 3266 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

/*
 * 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))
3326
		pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3327 3328 3329

	return 0;
}
3330
subsys_initcall(init_reserve_notifier);