memory.c 97.2 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

/*
 * demand-loading started 01.12.91 - seems it is high on the list of
 * things wanted, and it should be easy to implement. - Linus
 */

/*
 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
 * pages started 02.12.91, seems to work. - Linus.
 *
 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
 * would have taken more than the 6M I have free, but it worked well as
 * far as I could see.
 *
 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
 */

/*
 * Real VM (paging to/from disk) started 18.12.91. Much more work and
 * thought has to go into this. Oh, well..
 * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
 *		Found it. Everything seems to work now.
 * 20.12.91  -  Ok, making the swap-device changeable like the root.
 */

/*
 * 05.04.94  -  Multi-page memory management added for v1.1.
 * 		Idea by Alex Bligh (alex@cconcepts.co.uk)
 *
 * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
 *		(Gerhard.Wichert@pdb.siemens.de)
 *
 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
 */

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
#include <linux/module.h>
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#include <linux/delayacct.h>
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#include <linux/init.h>
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#include <linux/writeback.h>
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#include <linux/memcontrol.h>
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#include <linux/mmu_notifier.h>
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#include <linux/kallsyms.h>
#include <linux/swapops.h>
#include <linux/elf.h>
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#include <linux/gfp.h>
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#include <asm/io.h>
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#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>

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#include "internal.h"

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#ifndef CONFIG_NEED_MULTIPLE_NODES
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/* use the per-pgdat data instead for discontigmem - mbligh */
unsigned long max_mapnr;
struct page *mem_map;

EXPORT_SYMBOL(max_mapnr);
EXPORT_SYMBOL(mem_map);
#endif

unsigned long num_physpages;
/*
 * A number of key systems in x86 including ioremap() rely on the assumption
 * that high_memory defines the upper bound on direct map memory, then end
 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
 * and ZONE_HIGHMEM.
 */
void * high_memory;

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);

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/*
 * Randomize the address space (stacks, mmaps, brk, etc.).
 *
 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
 *   as ancient (libc5 based) binaries can segfault. )
 */
int randomize_va_space __read_mostly =
#ifdef CONFIG_COMPAT_BRK
					1;
#else
					2;
#endif
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static int __init disable_randmaps(char *s)
{
	randomize_va_space = 0;
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	return 1;
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}
__setup("norandmaps", disable_randmaps);

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unsigned long zero_pfn __read_mostly;
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unsigned long highest_memmap_pfn __read_mostly;
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/*
 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
 */
static int __init init_zero_pfn(void)
{
	zero_pfn = page_to_pfn(ZERO_PAGE(0));
	return 0;
}
core_initcall(init_zero_pfn);
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#if defined(SPLIT_RSS_COUNTING)

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static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
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{
	int i;

	for (i = 0; i < NR_MM_COUNTERS; i++) {
		if (task->rss_stat.count[i]) {
			add_mm_counter(mm, i, task->rss_stat.count[i]);
			task->rss_stat.count[i] = 0;
		}
	}
	task->rss_stat.events = 0;
}

static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
{
	struct task_struct *task = current;

	if (likely(task->mm == mm))
		task->rss_stat.count[member] += val;
	else
		add_mm_counter(mm, member, val);
}
#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)

/* sync counter once per 64 page faults */
#define TASK_RSS_EVENTS_THRESH	(64)
static void check_sync_rss_stat(struct task_struct *task)
{
	if (unlikely(task != current))
		return;
	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
		__sync_task_rss_stat(task, task->mm);
}

unsigned long get_mm_counter(struct mm_struct *mm, int member)
{
	long val = 0;

	/*
	 * Don't use task->mm here...for avoiding to use task_get_mm()..
	 * The caller must guarantee task->mm is not invalid.
	 */
	val = atomic_long_read(&mm->rss_stat.count[member]);
	/*
	 * counter is updated in asynchronous manner and may go to minus.
	 * But it's never be expected number for users.
	 */
	if (val < 0)
		return 0;
	return (unsigned long)val;
}

void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
{
	__sync_task_rss_stat(task, mm);
}
#else

#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)

static void check_sync_rss_stat(struct task_struct *task)
{
}

#endif

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/*
 * If a p?d_bad entry is found while walking page tables, report
 * the error, before resetting entry to p?d_none.  Usually (but
 * very seldom) called out from the p?d_none_or_clear_bad macros.
 */

void pgd_clear_bad(pgd_t *pgd)
{
	pgd_ERROR(*pgd);
	pgd_clear(pgd);
}

void pud_clear_bad(pud_t *pud)
{
	pud_ERROR(*pud);
	pud_clear(pud);
}

void pmd_clear_bad(pmd_t *pmd)
{
	pmd_ERROR(*pmd);
	pmd_clear(pmd);
}

/*
 * Note: this doesn't free the actual pages themselves. That
 * has been handled earlier when unmapping all the memory regions.
 */
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static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
			   unsigned long addr)
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{
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	pgtable_t token = pmd_pgtable(*pmd);
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	pmd_clear(pmd);
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	pte_free_tlb(tlb, token, addr);
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	tlb->mm->nr_ptes--;
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}

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static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
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{
	pmd_t *pmd;
	unsigned long next;
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	unsigned long start;
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	start = addr;
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	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			continue;
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		free_pte_range(tlb, pmd, addr);
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	} while (pmd++, addr = next, addr != end);

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	start &= PUD_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PUD_MASK;
		if (!ceiling)
			return;
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	}
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	if (end - 1 > ceiling - 1)
		return;

	pmd = pmd_offset(pud, start);
	pud_clear(pud);
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	pmd_free_tlb(tlb, pmd, start);
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}

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static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
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{
	pud_t *pud;
	unsigned long next;
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	unsigned long start;
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	start = addr;
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	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			continue;
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		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
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	} while (pud++, addr = next, addr != end);

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	start &= PGDIR_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PGDIR_MASK;
		if (!ceiling)
			return;
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	}
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	if (end - 1 > ceiling - 1)
		return;

	pud = pud_offset(pgd, start);
	pgd_clear(pgd);
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	pud_free_tlb(tlb, pud, start);
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}

/*
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 * This function frees user-level page tables of a process.
 *
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 * Must be called with pagetable lock held.
 */
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void free_pgd_range(struct mmu_gather *tlb,
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			unsigned long addr, unsigned long end,
			unsigned long floor, unsigned long ceiling)
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{
	pgd_t *pgd;
	unsigned long next;
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	/*
	 * The next few lines have given us lots of grief...
	 *
	 * Why are we testing PMD* at this top level?  Because often
	 * there will be no work to do at all, and we'd prefer not to
	 * go all the way down to the bottom just to discover that.
	 *
	 * Why all these "- 1"s?  Because 0 represents both the bottom
	 * of the address space and the top of it (using -1 for the
	 * top wouldn't help much: the masks would do the wrong thing).
	 * The rule is that addr 0 and floor 0 refer to the bottom of
	 * the address space, but end 0 and ceiling 0 refer to the top
	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
	 * that end 0 case should be mythical).
	 *
	 * Wherever addr is brought up or ceiling brought down, we must
	 * be careful to reject "the opposite 0" before it confuses the
	 * subsequent tests.  But what about where end is brought down
	 * by PMD_SIZE below? no, end can't go down to 0 there.
	 *
	 * Whereas we round start (addr) and ceiling down, by different
	 * masks at different levels, in order to test whether a table
	 * now has no other vmas using it, so can be freed, we don't
	 * bother to round floor or end up - the tests don't need that.
	 */
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	addr &= PMD_MASK;
	if (addr < floor) {
		addr += PMD_SIZE;
		if (!addr)
			return;
	}
	if (ceiling) {
		ceiling &= PMD_MASK;
		if (!ceiling)
			return;
	}
	if (end - 1 > ceiling - 1)
		end -= PMD_SIZE;
	if (addr > end - 1)
		return;

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	pgd = pgd_offset(tlb->mm, addr);
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	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
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		free_pud_range(tlb, pgd, addr, next, floor, ceiling);
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	} while (pgd++, addr = next, addr != end);
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}

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void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
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		unsigned long floor, unsigned long ceiling)
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{
	while (vma) {
		struct vm_area_struct *next = vma->vm_next;
		unsigned long addr = vma->vm_start;

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		/*
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		 * Hide vma from rmap and truncate_pagecache before freeing
		 * pgtables
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		 */
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		unlink_anon_vmas(vma);
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		unlink_file_vma(vma);

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		if (is_vm_hugetlb_page(vma)) {
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			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
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				floor, next? next->vm_start: ceiling);
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		} else {
			/*
			 * Optimization: gather nearby vmas into one call down
			 */
			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
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			       && !is_vm_hugetlb_page(next)) {
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				vma = next;
				next = vma->vm_next;
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				unlink_anon_vmas(vma);
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				unlink_file_vma(vma);
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			}
			free_pgd_range(tlb, addr, vma->vm_end,
				floor, next? next->vm_start: ceiling);
		}
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		vma = next;
	}
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}

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int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
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{
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	pgtable_t new = pte_alloc_one(mm, address);
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	if (!new)
		return -ENOMEM;

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	/*
	 * Ensure all pte setup (eg. pte page lock and page clearing) are
	 * visible before the pte is made visible to other CPUs by being
	 * put into page tables.
	 *
	 * The other side of the story is the pointer chasing in the page
	 * table walking code (when walking the page table without locking;
	 * ie. most of the time). Fortunately, these data accesses consist
	 * of a chain of data-dependent loads, meaning most CPUs (alpha
	 * being the notable exception) will already guarantee loads are
	 * seen in-order. See the alpha page table accessors for the
	 * smp_read_barrier_depends() barriers in page table walking code.
	 */
	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */

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	spin_lock(&mm->page_table_lock);
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	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
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		mm->nr_ptes++;
		pmd_populate(mm, pmd, new);
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		new = NULL;
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	}
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	spin_unlock(&mm->page_table_lock);
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	if (new)
		pte_free(mm, new);
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	return 0;
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}

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int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
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{
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	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
	if (!new)
		return -ENOMEM;

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	smp_wmb(); /* See comment in __pte_alloc */

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	spin_lock(&init_mm.page_table_lock);
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	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
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		pmd_populate_kernel(&init_mm, pmd, new);
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		new = NULL;
	}
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	spin_unlock(&init_mm.page_table_lock);
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	if (new)
		pte_free_kernel(&init_mm, new);
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	return 0;
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}

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static inline void init_rss_vec(int *rss)
{
	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
}

static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
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{
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	int i;

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	if (current->mm == mm)
		sync_mm_rss(current, mm);
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	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
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}

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/*
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 * This function is called to print an error when a bad pte
 * is found. For example, we might have a PFN-mapped pte in
 * a region that doesn't allow it.
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 *
 * The calling function must still handle the error.
 */
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static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
			  pte_t pte, struct page *page)
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{
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	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
	pud_t *pud = pud_offset(pgd, addr);
	pmd_t *pmd = pmd_offset(pud, addr);
	struct address_space *mapping;
	pgoff_t index;
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	static unsigned long resume;
	static unsigned long nr_shown;
	static unsigned long nr_unshown;

	/*
	 * Allow a burst of 60 reports, then keep quiet for that minute;
	 * or allow a steady drip of one report per second.
	 */
	if (nr_shown == 60) {
		if (time_before(jiffies, resume)) {
			nr_unshown++;
			return;
		}
		if (nr_unshown) {
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			printk(KERN_ALERT
				"BUG: Bad page map: %lu messages suppressed\n",
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				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
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	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
	index = linear_page_index(vma, addr);

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	printk(KERN_ALERT
		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
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		current->comm,
		(long long)pte_val(pte), (long long)pmd_val(*pmd));
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	if (page)
		dump_page(page);
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	printk(KERN_ALERT
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		"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
		(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
	/*
	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
	 */
	if (vma->vm_ops)
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		print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
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				(unsigned long)vma->vm_ops->fault);
	if (vma->vm_file && vma->vm_file->f_op)
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		print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
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				(unsigned long)vma->vm_file->f_op->mmap);
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	dump_stack();
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	add_taint(TAINT_BAD_PAGE);
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}

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static inline int is_cow_mapping(unsigned int flags)
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

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#ifndef is_zero_pfn
static inline int is_zero_pfn(unsigned long pfn)
{
	return pfn == zero_pfn;
}
#endif

#ifndef my_zero_pfn
static inline unsigned long my_zero_pfn(unsigned long addr)
{
	return zero_pfn;
}
#endif

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/*
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 * vm_normal_page -- This function gets the "struct page" associated with a pte.
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 *
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 * "Special" mappings do not wish to be associated with a "struct page" (either
 * it doesn't exist, or it exists but they don't want to touch it). In this
 * case, NULL is returned here. "Normal" mappings do have a struct page.
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 *
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 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 * pte bit, in which case this function is trivial. Secondly, an architecture
 * may not have a spare pte bit, which requires a more complicated scheme,
 * described below.
 *
 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 * special mapping (even if there are underlying and valid "struct pages").
 * COWed pages of a VM_PFNMAP are always normal.
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 *
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 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
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 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
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 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
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 * And for normal mappings this is false.
 *
 * This restricts such mappings to be a linear translation from virtual address
 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 * as the vma is not a COW mapping; in that case, we know that all ptes are
 * special (because none can have been COWed).
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 *
 *
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 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
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 *
 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 * page" backing, however the difference is that _all_ pages with a struct
 * page (that is, those where pfn_valid is true) are refcounted and considered
 * normal pages by the VM. The disadvantage is that pages are refcounted
 * (which can be slower and simply not an option for some PFNMAP users). The
 * advantage is that we don't have to follow the strict linearity rule of
 * PFNMAP mappings in order to support COWable mappings.
 *
H
Hugh Dickins 已提交
589
 */
N
Nick Piggin 已提交
590 591 592 593 594 595 596
#ifdef __HAVE_ARCH_PTE_SPECIAL
# define HAVE_PTE_SPECIAL 1
#else
# define HAVE_PTE_SPECIAL 0
#endif
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
				pte_t pte)
H
Hugh Dickins 已提交
597
{
598
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
599 600

	if (HAVE_PTE_SPECIAL) {
601 602
		if (likely(!pte_special(pte)))
			goto check_pfn;
H
Hugh Dickins 已提交
603 604
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
605
		if (!is_zero_pfn(pfn))
606
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
607 608 609 610 611
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
612 613 614 615 616 617
	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
N
Nick Piggin 已提交
618 619
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
620 621 622 623 624
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
625 626
	}

H
Hugh Dickins 已提交
627 628
	if (is_zero_pfn(pfn))
		return NULL;
629 630 631 632 633
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
634 635

	/*
N
Nick Piggin 已提交
636 637
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
638
	 */
J
Jared Hulbert 已提交
639
out:
640
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
641 642
}

L
Linus Torvalds 已提交
643 644 645 646 647 648
/*
 * copy one vm_area from one task to the other. Assumes the page tables
 * already present in the new task to be cleared in the whole range
 * covered by this vma.
 */

H
Hugh Dickins 已提交
649
static inline unsigned long
L
Linus Torvalds 已提交
650
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
651
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
652
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
653
{
N
Nick Piggin 已提交
654
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
655 656 657 658 659 660
	pte_t pte = *src_pte;
	struct page *page;

	/* pte contains position in swap or file, so copy. */
	if (unlikely(!pte_present(pte))) {
		if (!pte_file(pte)) {
661 662
			swp_entry_t entry = pte_to_swp_entry(pte);

H
Hugh Dickins 已提交
663 664 665
			if (swap_duplicate(entry) < 0)
				return entry.val;

L
Linus Torvalds 已提交
666 667 668
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
669 670 671
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
672 673
				spin_unlock(&mmlist_lock);
			}
K
KAMEZAWA Hiroyuki 已提交
674 675 676
			if (likely(!non_swap_entry(entry)))
				rss[MM_SWAPENTS]++;
			else if (is_write_migration_entry(entry) &&
677 678 679 680 681 682 683 684 685
					is_cow_mapping(vm_flags)) {
				/*
				 * COW mappings require pages in both parent
				 * and child to be set to read.
				 */
				make_migration_entry_read(&entry);
				pte = swp_entry_to_pte(entry);
				set_pte_at(src_mm, addr, src_pte, pte);
			}
L
Linus Torvalds 已提交
686
		}
687
		goto out_set_pte;
L
Linus Torvalds 已提交
688 689 690 691 692 693
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
694
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
695
		ptep_set_wrprotect(src_mm, addr, src_pte);
696
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
697 698 699 700 701 702 703 704 705
	}

	/*
	 * If it's a shared mapping, mark it clean in
	 * the child
	 */
	if (vm_flags & VM_SHARED)
		pte = pte_mkclean(pte);
	pte = pte_mkold(pte);
706 707 708 709

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
H
Hugh Dickins 已提交
710
		page_dup_rmap(page);
K
KAMEZAWA Hiroyuki 已提交
711 712 713 714
		if (PageAnon(page))
			rss[MM_ANONPAGES]++;
		else
			rss[MM_FILEPAGES]++;
715
	}
716 717 718

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
719
	return 0;
L
Linus Torvalds 已提交
720 721 722 723 724 725
}

static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
726
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
727
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
728
	spinlock_t *src_ptl, *dst_ptl;
729
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
730
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
731
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
732 733

again:
K
KAMEZAWA Hiroyuki 已提交
734 735
	init_rss_vec(rss);

H
Hugh Dickins 已提交
736
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
737 738
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
739
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
740
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
741
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
742 743
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
744
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
745 746 747 748 749 750

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
751 752 753
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
754
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
755 756
				break;
		}
L
Linus Torvalds 已提交
757 758 759 760
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
761 762 763 764
		entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
							vma, addr, rss);
		if (entry.val)
			break;
L
Linus Torvalds 已提交
765 766 767
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

768
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
769
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
770
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
771
	add_mm_rss_vec(dst_mm, rss);
772
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
773
	cond_resched();
H
Hugh Dickins 已提交
774 775 776 777 778 779

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835
	if (addr != end)
		goto again;
	return 0;
}

static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pmd_t *src_pmd, *dst_pmd;
	unsigned long next;

	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
	if (!dst_pmd)
		return -ENOMEM;
	src_pmd = pmd_offset(src_pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(src_pmd))
			continue;
		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
	return 0;
}

static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pud_t *src_pud, *dst_pud;
	unsigned long next;

	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
	if (!dst_pud)
		return -ENOMEM;
	src_pud = pud_offset(src_pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(src_pud))
			continue;
		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pud++, src_pud++, addr = next, addr != end);
	return 0;
}

int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		struct vm_area_struct *vma)
{
	pgd_t *src_pgd, *dst_pgd;
	unsigned long next;
	unsigned long addr = vma->vm_start;
	unsigned long end = vma->vm_end;
A
Andrea Arcangeli 已提交
836
	int ret;
L
Linus Torvalds 已提交
837

838 839 840 841 842 843
	/*
	 * Don't copy ptes where a page fault will fill them correctly.
	 * Fork becomes much lighter when there are big shared or private
	 * readonly mappings. The tradeoff is that copy_page_range is more
	 * efficient than faulting.
	 */
844
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
845 846 847 848
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
849 850 851
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

852
	if (unlikely(is_pfn_mapping(vma))) {
853 854 855 856 857 858 859 860 861
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
		ret = track_pfn_vma_copy(vma);
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
862 863 864 865 866 867 868 869 870 871
	/*
	 * We need to invalidate the secondary MMU mappings only when
	 * there could be a permission downgrade on the ptes of the
	 * parent mm. And a permission downgrade will only happen if
	 * is_cow_mapping() returns true.
	 */
	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_start(src_mm, addr, end);

	ret = 0;
L
Linus Torvalds 已提交
872 873 874 875 876 877
	dst_pgd = pgd_offset(dst_mm, addr);
	src_pgd = pgd_offset(src_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(src_pgd))
			continue;
A
Andrea Arcangeli 已提交
878 879 880 881 882
		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
					    vma, addr, next))) {
			ret = -ENOMEM;
			break;
		}
L
Linus Torvalds 已提交
883
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
884 885 886 887 888

	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_end(src_mm,
						  vma->vm_start, end);
	return ret;
L
Linus Torvalds 已提交
889 890
}

891
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
892
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
893
				unsigned long addr, unsigned long end,
894
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
895
{
N
Nick Piggin 已提交
896
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
897
	pte_t *pte;
898
	spinlock_t *ptl;
K
KAMEZAWA Hiroyuki 已提交
899 900 901
	int rss[NR_MM_COUNTERS];

	init_rss_vec(rss);
L
Linus Torvalds 已提交
902

903
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
904
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
905 906
	do {
		pte_t ptent = *pte;
907 908
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
909
			continue;
910
		}
911 912 913

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
914
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
915
			struct page *page;
916

917
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
				    details->check_mapping != page->mapping)
					continue;
				/*
				 * Each page->index must be checked when
				 * invalidating or truncating nonlinear.
				 */
				if (details->nonlinear_vma &&
				    (page->index < details->first_index ||
				     page->index > details->last_index))
					continue;
			}
N
Nick Piggin 已提交
936
			ptent = ptep_get_and_clear_full(mm, addr, pte,
937
							tlb->fullmm);
L
Linus Torvalds 已提交
938 939 940 941 942 943
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (unlikely(details) && details->nonlinear_vma
			    && linear_page_index(details->nonlinear_vma,
						addr) != page->index)
N
Nick Piggin 已提交
944
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
945 946
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
K
KAMEZAWA Hiroyuki 已提交
947
				rss[MM_ANONPAGES]--;
948 949 950
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
951 952
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
953
					mark_page_accessed(page);
K
KAMEZAWA Hiroyuki 已提交
954
				rss[MM_FILEPAGES]--;
955
			}
956
			page_remove_rmap(page);
957 958
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
L
Linus Torvalds 已提交
959 960 961 962 963 964 965 966 967
			tlb_remove_page(tlb, page);
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
968 969 970
		if (pte_file(ptent)) {
			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
				print_bad_pte(vma, addr, ptent, NULL);
K
KAMEZAWA Hiroyuki 已提交
971 972 973 974 975 976 977 978
		} else {
			swp_entry_t entry = pte_to_swp_entry(ptent);

			if (!non_swap_entry(entry))
				rss[MM_SWAPENTS]--;
			if (unlikely(!free_swap_and_cache(entry)))
				print_bad_pte(vma, addr, ptent, NULL);
		}
979
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
980
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
981

K
KAMEZAWA Hiroyuki 已提交
982
	add_mm_rss_vec(mm, rss);
983
	arch_leave_lazy_mmu_mode();
984
	pte_unmap_unlock(pte - 1, ptl);
985 986

	return addr;
L
Linus Torvalds 已提交
987 988
}

989
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
990
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
991
				unsigned long addr, unsigned long end,
992
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
993 994 995 996 997 998 999
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1000 1001
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
1002
			continue;
1003 1004 1005 1006 1007 1008
		}
		next = zap_pte_range(tlb, vma, pmd, addr, next,
						zap_work, details);
	} while (pmd++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
1009 1010
}

1011
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1012
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1013
				unsigned long addr, unsigned long end,
1014
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
1015 1016 1017 1018 1019 1020 1021
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1022 1023
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
1024
			continue;
1025 1026 1027 1028 1029 1030
		}
		next = zap_pmd_range(tlb, vma, pud, addr, next,
						zap_work, details);
	} while (pud++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
1031 1032
}

1033 1034
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
1035
				unsigned long addr, unsigned long end,
1036
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
1037 1038 1039 1040 1041 1042 1043 1044
{
	pgd_t *pgd;
	unsigned long next;

	if (details && !details->check_mapping && !details->nonlinear_vma)
		details = NULL;

	BUG_ON(addr >= end);
1045
	mem_cgroup_uncharge_start();
L
Linus Torvalds 已提交
1046 1047 1048 1049
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
1050 1051
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
1052
			continue;
1053 1054 1055 1056
		}
		next = zap_pud_range(tlb, vma, pgd, addr, next,
						zap_work, details);
	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
L
Linus Torvalds 已提交
1057
	tlb_end_vma(tlb, vma);
1058
	mem_cgroup_uncharge_end();
1059 1060

	return addr;
L
Linus Torvalds 已提交
1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078
}

#ifdef CONFIG_PREEMPT
# define ZAP_BLOCK_SIZE	(8 * PAGE_SIZE)
#else
/* No preempt: go for improved straight-line efficiency */
# define ZAP_BLOCK_SIZE	(1024 * PAGE_SIZE)
#endif

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
 * @tlbp: address of the caller's struct mmu_gather
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
 * @details: details of nonlinear truncation or shared cache invalidation
 *
1079
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
1080
 *
1081
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1082
 *
1083 1084
 * We aim to not hold locks for too long (for scheduling latency reasons).
 * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
L
Linus Torvalds 已提交
1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095
 * return the ending mmu_gather to the caller.
 *
 * Only addresses between `start' and `end' will be unmapped.
 *
 * The VMA list must be sorted in ascending virtual address order.
 *
 * unmap_vmas() assumes that the caller will flush the whole unmapped address
 * range after unmap_vmas() returns.  So the only responsibility here is to
 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
 * drops the lock and schedules.
 */
1096
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
1097 1098 1099 1100
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
1101
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1102 1103
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
1104
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
1105
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
1106
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
1107
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1108

A
Andrea Arcangeli 已提交
1109
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
		unsigned long end;

		start = max(vma->vm_start, start_addr);
		if (start >= vma->vm_end)
			continue;
		end = min(vma->vm_end, end_addr);
		if (end <= vma->vm_start)
			continue;

		if (vma->vm_flags & VM_ACCOUNT)
			*nr_accounted += (end - start) >> PAGE_SHIFT;

1123
		if (unlikely(is_pfn_mapping(vma)))
1124 1125
			untrack_pfn_vma(vma, 0, 0);

L
Linus Torvalds 已提交
1126 1127 1128 1129 1130 1131
		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

1132
			if (unlikely(is_vm_hugetlb_page(vma))) {
1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146
				/*
				 * It is undesirable to test vma->vm_file as it
				 * should be non-null for valid hugetlb area.
				 * However, vm_file will be NULL in the error
				 * cleanup path of do_mmap_pgoff. When
				 * hugetlbfs ->mmap method fails,
				 * do_mmap_pgoff() nullifies vma->vm_file
				 * before calling this function to clean up.
				 * Since no pte has actually been setup, it is
				 * safe to do nothing in this case.
				 */
				if (vma->vm_file) {
					unmap_hugepage_range(vma, start, end, NULL);
					zap_work -= (end - start) /
1147
					pages_per_huge_page(hstate_vma(vma));
1148 1149
				}

1150 1151 1152 1153 1154 1155 1156 1157
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

			if (zap_work > 0) {
				BUG_ON(start != end);
				break;
L
Linus Torvalds 已提交
1158 1159 1160 1161 1162
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
1163
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
1164
				if (i_mmap_lock) {
1165
					*tlbp = NULL;
L
Linus Torvalds 已提交
1166 1167 1168 1169 1170
					goto out;
				}
				cond_resched();
			}

1171
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
1172
			tlb_start_valid = 0;
1173
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1174 1175 1176
		}
	}
out:
A
Andrea Arcangeli 已提交
1177
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1178
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
1179 1180 1181 1182 1183 1184 1185 1186 1187
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 * @details: details of nonlinear truncation or shared cache invalidation
 */
1188
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1189 1190 1191 1192 1193 1194 1195 1196 1197
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
	struct mmu_gather *tlb;
	unsigned long end = address + size;
	unsigned long nr_accounted = 0;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
1198
	update_hiwater_rss(mm);
1199 1200 1201
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
1202
	return end;
L
Linus Torvalds 已提交
1203 1204
}

1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227
/**
 * zap_vma_ptes - remove ptes mapping the vma
 * @vma: vm_area_struct holding ptes to be zapped
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 *
 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
 *
 * The entire address range must be fully contained within the vma.
 *
 * Returns 0 if successful.
 */
int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
		unsigned long size)
{
	if (address < vma->vm_start || address + size > vma->vm_end ||
	    		!(vma->vm_flags & VM_PFNMAP))
		return -1;
	zap_page_range(vma, address, size, NULL);
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

J
Johannes Weiner 已提交
1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238
/**
 * follow_page - look up a page descriptor from a user-virtual address
 * @vma: vm_area_struct mapping @address
 * @address: virtual address to look up
 * @flags: flags modifying lookup behaviour
 *
 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
 *
 * Returns the mapped (struct page *), %NULL if no mapping exists, or
 * an error pointer if there is a mapping to something not represented
 * by a page descriptor (see also vm_normal_page()).
L
Linus Torvalds 已提交
1239
 */
1240
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1241
			unsigned int flags)
L
Linus Torvalds 已提交
1242 1243 1244 1245 1246
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1247
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1248
	struct page *page;
1249
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1250

1251 1252 1253 1254 1255
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
L
Linus Torvalds 已提交
1256

1257
	page = NULL;
L
Linus Torvalds 已提交
1258 1259
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1260
		goto no_page_table;
L
Linus Torvalds 已提交
1261 1262

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1263
	if (pud_none(*pud))
1264
		goto no_page_table;
A
Andi Kleen 已提交
1265 1266 1267 1268 1269 1270 1271 1272
	if (pud_huge(*pud)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
		goto out;
	}
	if (unlikely(pud_bad(*pud)))
		goto no_page_table;

L
Linus Torvalds 已提交
1273
	pmd = pmd_offset(pud, address);
1274
	if (pmd_none(*pmd))
1275 1276 1277 1278
		goto no_page_table;
	if (pmd_huge(*pmd)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
L
Linus Torvalds 已提交
1279
		goto out;
1280
	}
1281 1282 1283
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1284
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1285 1286

	pte = *ptep;
1287
	if (!pte_present(pte))
1288
		goto no_page;
1289 1290
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
H
Hugh Dickins 已提交
1291

1292
	page = vm_normal_page(vma, address, pte);
H
Hugh Dickins 已提交
1293 1294
	if (unlikely(!page)) {
		if ((flags & FOLL_DUMP) ||
H
Hugh Dickins 已提交
1295
		    !is_zero_pfn(pte_pfn(pte)))
H
Hugh Dickins 已提交
1296 1297 1298
			goto bad_page;
		page = pte_page(pte);
	}
L
Linus Torvalds 已提交
1299

1300 1301 1302 1303 1304 1305
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
1306 1307 1308 1309 1310
		/*
		 * pte_mkyoung() would be more correct here, but atomic care
		 * is needed to avoid losing the dirty bit: it is easier to use
		 * mark_page_accessed().
		 */
1311 1312 1313 1314
		mark_page_accessed(page);
	}
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1315
out:
1316
	return page;
L
Linus Torvalds 已提交
1317

1318 1319 1320 1321 1322 1323 1324 1325
bad_page:
	pte_unmap_unlock(ptep, ptl);
	return ERR_PTR(-EFAULT);

no_page:
	pte_unmap_unlock(ptep, ptl);
	if (!pte_none(pte))
		return page;
H
Hugh Dickins 已提交
1326

1327 1328 1329
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
H
Hugh Dickins 已提交
1330 1331 1332 1333 1334
	 * has touched so far, we don't want to allocate unnecessary pages or
	 * page tables.  Return error instead of NULL to skip handle_mm_fault,
	 * then get_dump_page() will return NULL to leave a hole in the dump.
	 * But we can only make this optimization where a hole would surely
	 * be zero-filled if handle_mm_fault() actually did handle it.
1335
	 */
H
Hugh Dickins 已提交
1336 1337 1338
	if ((flags & FOLL_DUMP) &&
	    (!vma->vm_ops || !vma->vm_ops->fault))
		return ERR_PTR(-EFAULT);
1339
	return page;
L
Linus Torvalds 已提交
1340 1341
}

N
Nick Piggin 已提交
1342
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
H
Hugh Dickins 已提交
1343
		     unsigned long start, int nr_pages, unsigned int gup_flags,
1344
		     struct page **pages, struct vm_area_struct **vmas)
L
Linus Torvalds 已提交
1345 1346
{
	int i;
H
Hugh Dickins 已提交
1347
	unsigned long vm_flags;
L
Linus Torvalds 已提交
1348

1349
	if (nr_pages <= 0)
1350
		return 0;
H
Hugh Dickins 已提交
1351 1352 1353

	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));

L
Linus Torvalds 已提交
1354 1355
	/* 
	 * Require read or write permissions.
H
Hugh Dickins 已提交
1356
	 * If FOLL_FORCE is set, we only require the "MAY" flags.
L
Linus Torvalds 已提交
1357
	 */
H
Hugh Dickins 已提交
1358 1359 1360 1361
	vm_flags  = (gup_flags & FOLL_WRITE) ?
			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= (gup_flags & FOLL_FORCE) ?
			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
Linus Torvalds 已提交
1362 1363 1364
	i = 0;

	do {
1365
		struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1366 1367 1368 1369 1370 1371 1372 1373 1374

		vma = find_extend_vma(mm, start);
		if (!vma && in_gate_area(tsk, start)) {
			unsigned long pg = start & PAGE_MASK;
			struct vm_area_struct *gate_vma = get_gate_vma(tsk);
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
N
Nick Piggin 已提交
1375 1376

			/* user gate pages are read-only */
H
Hugh Dickins 已提交
1377
			if (gup_flags & FOLL_WRITE)
L
Linus Torvalds 已提交
1378 1379 1380 1381 1382 1383 1384 1385 1386
				return i ? : -EFAULT;
			if (pg > TASK_SIZE)
				pgd = pgd_offset_k(pg);
			else
				pgd = pgd_offset_gate(mm, pg);
			BUG_ON(pgd_none(*pgd));
			pud = pud_offset(pgd, pg);
			BUG_ON(pud_none(*pud));
			pmd = pmd_offset(pud, pg);
1387 1388
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1389
			pte = pte_offset_map(pmd, pg);
1390 1391 1392 1393
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1394
			if (pages) {
1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406
				struct page *page;

				page = vm_normal_page(gate_vma, start, *pte);
				if (!page) {
					if (!(gup_flags & FOLL_DUMP) &&
					     is_zero_pfn(pte_pfn(*pte)))
						page = pte_page(*pte);
					else {
						pte_unmap(pte);
						return i ? : -EFAULT;
					}
				}
1407
				pages[i] = page;
1408
				get_page(page);
L
Linus Torvalds 已提交
1409 1410 1411 1412 1413 1414
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
1415
			nr_pages--;
L
Linus Torvalds 已提交
1416 1417 1418
			continue;
		}

N
Nick Piggin 已提交
1419 1420
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
H
Hugh Dickins 已提交
1421
		    !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1422 1423
			return i ? : -EFAULT;

H
Hugh Dickins 已提交
1424 1425
		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
H
Hugh Dickins 已提交
1426
					&start, &nr_pages, i, gup_flags);
H
Hugh Dickins 已提交
1427 1428
			continue;
		}
1429

L
Linus Torvalds 已提交
1430
		do {
1431
			struct page *page;
H
Hugh Dickins 已提交
1432
			unsigned int foll_flags = gup_flags;
L
Linus Torvalds 已提交
1433

1434
			/*
1435
			 * If we have a pending SIGKILL, don't keep faulting
H
Hugh Dickins 已提交
1436
			 * pages and potentially allocating memory.
1437
			 */
H
Hugh Dickins 已提交
1438
			if (unlikely(fatal_signal_pending(current)))
1439
				return i ? i : -ERESTARTSYS;
1440

1441
			cond_resched();
1442
			while (!(page = follow_page(vma, start, foll_flags))) {
1443
				int ret;
1444

1445 1446 1447 1448
				ret = handle_mm_fault(mm, vma, start,
					(foll_flags & FOLL_WRITE) ?
					FAULT_FLAG_WRITE : 0);

N
Nick Piggin 已提交
1449 1450 1451
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
1452
					if (ret &
1453 1454
					    (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE|
					     VM_FAULT_SIGBUS))
N
Nick Piggin 已提交
1455 1456 1457 1458 1459 1460 1461 1462
						return i ? i : -EFAULT;
					BUG();
				}
				if (ret & VM_FAULT_MAJOR)
					tsk->maj_flt++;
				else
					tsk->min_flt++;

1463
				/*
N
Nick Piggin 已提交
1464 1465 1466 1467
				 * The VM_FAULT_WRITE bit tells us that
				 * do_wp_page has broken COW when necessary,
				 * even if maybe_mkwrite decided not to set
				 * pte_write. We can thus safely do subsequent
1468 1469 1470 1471 1472 1473
				 * page lookups as if they were reads. But only
				 * do so when looping for pte_write is futile:
				 * in some cases userspace may also be wanting
				 * to write to the gotten user page, which a
				 * read fault here might prevent (a readonly
				 * page might get reCOWed by userspace write).
1474
				 */
1475 1476
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1477
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1478

1479
				cond_resched();
L
Linus Torvalds 已提交
1480
			}
1481 1482
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1483
			if (pages) {
1484
				pages[i] = page;
1485

1486
				flush_anon_page(vma, page, start);
1487
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1488 1489 1490 1491 1492
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
1493 1494 1495
			nr_pages--;
		} while (nr_pages && start < vma->vm_end);
	} while (nr_pages);
L
Linus Torvalds 已提交
1496 1497
	return i;
}
N
Nick Piggin 已提交
1498

1499 1500 1501 1502 1503
/**
 * get_user_pages() - pin user pages in memory
 * @tsk:	task_struct of target task
 * @mm:		mm_struct of target mm
 * @start:	starting user address
1504
 * @nr_pages:	number of pages from start to pin
1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515
 * @write:	whether pages will be written to by the caller
 * @force:	whether to force write access even if user mapping is
 *		readonly. This will result in the page being COWed even
 *		in MAP_SHARED mappings. You do not want this.
 * @pages:	array that receives pointers to the pages pinned.
 *		Should be at least nr_pages long. Or NULL, if caller
 *		only intends to ensure the pages are faulted in.
 * @vmas:	array of pointers to vmas corresponding to each page.
 *		Or NULL if the caller does not require them.
 *
 * Returns number of pages pinned. This may be fewer than the number
1516
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548
 * were pinned, returns -errno. Each page returned must be released
 * with a put_page() call when it is finished with. vmas will only
 * remain valid while mmap_sem is held.
 *
 * Must be called with mmap_sem held for read or write.
 *
 * get_user_pages walks a process's page tables and takes a reference to
 * each struct page that each user address corresponds to at a given
 * instant. That is, it takes the page that would be accessed if a user
 * thread accesses the given user virtual address at that instant.
 *
 * This does not guarantee that the page exists in the user mappings when
 * get_user_pages returns, and there may even be a completely different
 * page there in some cases (eg. if mmapped pagecache has been invalidated
 * and subsequently re faulted). However it does guarantee that the page
 * won't be freed completely. And mostly callers simply care that the page
 * contains data that was valid *at some point in time*. Typically, an IO
 * or similar operation cannot guarantee anything stronger anyway because
 * locks can't be held over the syscall boundary.
 *
 * If write=0, the page must not be written to. If the page is written to,
 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
 * after the page is finished with, and before put_page is called.
 *
 * get_user_pages is typically used for fewer-copy IO operations, to get a
 * handle on the memory by some means other than accesses via the user virtual
 * addresses. The pages may be submitted for DMA to devices or accessed via
 * their kernel linear mapping (via the kmap APIs). Care should be taken to
 * use the correct cache flushing APIs.
 *
 * See also get_user_pages_fast, for performance critical applications.
 */
N
Nick Piggin 已提交
1549
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1550
		unsigned long start, int nr_pages, int write, int force,
N
Nick Piggin 已提交
1551 1552
		struct page **pages, struct vm_area_struct **vmas)
{
H
Hugh Dickins 已提交
1553
	int flags = FOLL_TOUCH;
N
Nick Piggin 已提交
1554

H
Hugh Dickins 已提交
1555 1556
	if (pages)
		flags |= FOLL_GET;
N
Nick Piggin 已提交
1557
	if (write)
H
Hugh Dickins 已提交
1558
		flags |= FOLL_WRITE;
N
Nick Piggin 已提交
1559
	if (force)
H
Hugh Dickins 已提交
1560
		flags |= FOLL_FORCE;
N
Nick Piggin 已提交
1561

1562
	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
N
Nick Piggin 已提交
1563
}
L
Linus Torvalds 已提交
1564 1565
EXPORT_SYMBOL(get_user_pages);

H
Hugh Dickins 已提交
1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586
/**
 * get_dump_page() - pin user page in memory while writing it to core dump
 * @addr: user address
 *
 * Returns struct page pointer of user page pinned for dump,
 * to be freed afterwards by page_cache_release() or put_page().
 *
 * Returns NULL on any kind of failure - a hole must then be inserted into
 * the corefile, to preserve alignment with its headers; and also returns
 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
 * allowing a hole to be left in the corefile to save diskspace.
 *
 * Called without mmap_sem, but after all other threads have been killed.
 */
#ifdef CONFIG_ELF_CORE
struct page *get_dump_page(unsigned long addr)
{
	struct vm_area_struct *vma;
	struct page *page;

	if (__get_user_pages(current, current->mm, addr, 1,
H
Hugh Dickins 已提交
1587
			FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1)
H
Hugh Dickins 已提交
1588 1589 1590 1591 1592 1593
		return NULL;
	flush_cache_page(vma, addr, page_to_pfn(page));
	return page;
}
#endif /* CONFIG_ELF_CORE */

H
Harvey Harrison 已提交
1594 1595
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1596 1597 1598 1599
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1600
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1601 1602 1603 1604 1605 1606
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1607 1608 1609 1610 1611 1612 1613
/*
 * This is the old fallback for page remapping.
 *
 * For historical reasons, it only allows reserved pages. Only
 * old drivers should use this, and they needed to mark their
 * pages reserved for the old functions anyway.
 */
N
Nick Piggin 已提交
1614 1615
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1616
{
N
Nick Piggin 已提交
1617
	struct mm_struct *mm = vma->vm_mm;
1618
	int retval;
1619
	pte_t *pte;
1620 1621
	spinlock_t *ptl;

1622
	retval = -EINVAL;
1623
	if (PageAnon(page))
1624
		goto out;
1625 1626
	retval = -ENOMEM;
	flush_dcache_page(page);
1627
	pte = get_locked_pte(mm, addr, &ptl);
1628
	if (!pte)
1629
		goto out;
1630 1631 1632 1633 1634 1635
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
1636
	inc_mm_counter_fast(mm, MM_FILEPAGES);
1637 1638 1639 1640
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1641 1642
	pte_unmap_unlock(pte, ptl);
	return retval;
1643 1644 1645 1646 1647 1648
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1649 1650 1651 1652 1653 1654
/**
 * vm_insert_page - insert single page into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @page: source kernel page
 *
1655 1656 1657 1658 1659 1660
 * This allows drivers to insert individual pages they've allocated
 * into a user vma.
 *
 * The page has to be a nice clean _individual_ kernel allocation.
 * If you allocate a compound page, you need to have marked it as
 * such (__GFP_COMP), or manually just split the page up yourself
N
Nick Piggin 已提交
1661
 * (see split_page()).
1662 1663 1664 1665 1666 1667 1668 1669 1670
 *
 * NOTE! Traditionally this was done with "remap_pfn_range()" which
 * took an arbitrary page protection parameter. This doesn't allow
 * that. Your vma protection will have to be set up correctly, which
 * means that if you want a shared writable mapping, you'd better
 * ask for a shared writable mapping!
 *
 * The page does not need to be reserved.
 */
N
Nick Piggin 已提交
1671 1672
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1673 1674 1675 1676 1677
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1678
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1679
	return insert_page(vma, addr, page, vma->vm_page_prot);
1680
}
1681
EXPORT_SYMBOL(vm_insert_page);
1682

N
Nick Piggin 已提交
1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn, pgprot_t prot)
{
	struct mm_struct *mm = vma->vm_mm;
	int retval;
	pte_t *pte, entry;
	spinlock_t *ptl;

	retval = -ENOMEM;
	pte = get_locked_pte(mm, addr, &ptl);
	if (!pte)
		goto out;
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	entry = pte_mkspecial(pfn_pte(pfn, prot));
	set_pte_at(mm, addr, pte, entry);
1702
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1703 1704 1705 1706 1707 1708 1709 1710

	retval = 0;
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

N
Nick Piggin 已提交
1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721
/**
 * vm_insert_pfn - insert single pfn into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @pfn: source kernel pfn
 *
 * Similar to vm_inert_page, this allows drivers to insert individual pages
 * they've allocated into a user vma. Same comments apply.
 *
 * This function should only be called from a vm_ops->fault handler, and
 * in that case the handler should return NULL.
N
Nick Piggin 已提交
1722 1723 1724 1725 1726
 *
 * vma cannot be a COW mapping.
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
N
Nick Piggin 已提交
1727 1728
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1729
			unsigned long pfn)
N
Nick Piggin 已提交
1730
{
1731
	int ret;
1732
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1733 1734 1735 1736 1737 1738
	/*
	 * Technically, architectures with pte_special can avoid all these
	 * restrictions (same for remap_pfn_range).  However we would like
	 * consistency in testing and feature parity among all, so we should
	 * try to keep these invariants in place for everybody.
	 */
J
Jared Hulbert 已提交
1739 1740 1741 1742 1743
	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
						(VM_PFNMAP|VM_MIXEDMAP));
	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
N
Nick Piggin 已提交
1744

N
Nick Piggin 已提交
1745 1746
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1747
	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1748 1749
		return -EINVAL;

1750
	ret = insert_pfn(vma, addr, pfn, pgprot);
1751 1752 1753 1754 1755

	if (ret)
		untrack_pfn_vma(vma, pfn, PAGE_SIZE);

	return ret;
N
Nick Piggin 已提交
1756 1757
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1758

N
Nick Piggin 已提交
1759 1760 1761 1762
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn)
{
	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
N
Nick Piggin 已提交
1763

N
Nick Piggin 已提交
1764 1765
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1766

N
Nick Piggin 已提交
1767 1768 1769 1770
	/*
	 * If we don't have pte special, then we have to use the pfn_valid()
	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
	 * refcount the page if pfn_valid is true (hence insert_page rather
H
Hugh Dickins 已提交
1771 1772
	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
	 * without pte special, it would there be refcounted as a normal page.
N
Nick Piggin 已提交
1773 1774 1775 1776 1777 1778 1779 1780
	 */
	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
		struct page *page;

		page = pfn_to_page(pfn);
		return insert_page(vma, addr, page, vma->vm_page_prot);
	}
	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
N
Nick Piggin 已提交
1781
}
N
Nick Piggin 已提交
1782
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1783

L
Linus Torvalds 已提交
1784 1785 1786 1787 1788 1789 1790 1791 1792 1793
/*
 * maps a range of physical memory into the requested pages. the old
 * mappings are removed. any references to nonexistent pages results
 * in null mappings (currently treated as "copy-on-access")
 */
static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pte_t *pte;
H
Hugh Dickins 已提交
1794
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1795

H
Hugh Dickins 已提交
1796
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1797 1798
	if (!pte)
		return -ENOMEM;
1799
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1800 1801
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1802
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1803 1804
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1805
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1806
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
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
	return 0;
}

static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pmd_t *pmd;
	unsigned long next;

	pfn -= addr >> PAGE_SHIFT;
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		if (remap_pte_range(mm, pmd, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot))
			return -ENOMEM;
	} while (pmd++, addr = next, addr != end);
	return 0;
}

static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pud_t *pud;
	unsigned long next;

	pfn -= addr >> PAGE_SHIFT;
	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return -ENOMEM;
	do {
		next = pud_addr_end(addr, end);
		if (remap_pmd_range(mm, pud, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot))
			return -ENOMEM;
	} while (pud++, addr = next, addr != end);
	return 0;
}

1850 1851 1852 1853 1854 1855 1856 1857 1858 1859
/**
 * remap_pfn_range - remap kernel memory to userspace
 * @vma: user vma to map to
 * @addr: target user address to start at
 * @pfn: physical address of kernel memory
 * @size: size of map area
 * @prot: page protection flags for this mapping
 *
 *  Note: this is only safe if the mm semaphore is held when called.
 */
L
Linus Torvalds 已提交
1860 1861 1862 1863 1864
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
		    unsigned long pfn, unsigned long size, pgprot_t prot)
{
	pgd_t *pgd;
	unsigned long next;
1865
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1866 1867 1868 1869 1870 1871 1872 1873
	struct mm_struct *mm = vma->vm_mm;
	int err;

	/*
	 * Physically remapped pages are special. Tell the
	 * rest of the world about it:
	 *   VM_IO tells people not to look at these pages
	 *	(accesses can have side effects).
H
Hugh Dickins 已提交
1874 1875 1876 1877 1878
	 *   VM_RESERVED is specified all over the place, because
	 *	in 2.4 it kept swapout's vma scan off this vma; but
	 *	in 2.6 the LRU scan won't even find its pages, so this
	 *	flag means no more than count its pages in reserved_vm,
	 * 	and omit it from core dump, even when VM_IO turned off.
1879 1880 1881
	 *   VM_PFNMAP tells the core MM that the base pages are just
	 *	raw PFN mappings, and do not have a "struct page" associated
	 *	with them.
L
Linus Torvalds 已提交
1882 1883 1884 1885
	 *
	 * There's a horrible special case to handle copy-on-write
	 * behaviour that some programs depend on. We mark the "original"
	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
L
Linus Torvalds 已提交
1886
	 */
1887
	if (addr == vma->vm_start && end == vma->vm_end) {
L
Linus Torvalds 已提交
1888
		vma->vm_pgoff = pfn;
1889
		vma->vm_flags |= VM_PFN_AT_MMAP;
1890
	} else if (is_cow_mapping(vma->vm_flags))
1891
		return -EINVAL;
L
Linus Torvalds 已提交
1892

1893
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1894

1895
	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1896 1897 1898 1899 1900 1901
	if (err) {
		/*
		 * To indicate that track_pfn related cleanup is not
		 * needed from higher level routine calling unmap_vmas
		 */
		vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
1902
		vma->vm_flags &= ~VM_PFN_AT_MMAP;
1903
		return -EINVAL;
1904
	}
1905

L
Linus Torvalds 已提交
1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916
	BUG_ON(addr >= end);
	pfn -= addr >> PAGE_SHIFT;
	pgd = pgd_offset(mm, addr);
	flush_cache_range(vma, addr, end);
	do {
		next = pgd_addr_end(addr, end);
		err = remap_pud_range(mm, pgd, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
1917 1918 1919 1920

	if (err)
		untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));

L
Linus Torvalds 已提交
1921 1922 1923 1924
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1925 1926 1927 1928 1929 1930
static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pte_t *pte;
	int err;
1931
	pgtable_t token;
1932
	spinlock_t *uninitialized_var(ptl);
1933 1934 1935 1936 1937 1938 1939 1940 1941

	pte = (mm == &init_mm) ?
		pte_alloc_kernel(pmd, addr) :
		pte_alloc_map_lock(mm, pmd, addr, &ptl);
	if (!pte)
		return -ENOMEM;

	BUG_ON(pmd_huge(*pmd));

1942 1943
	arch_enter_lazy_mmu_mode();

1944
	token = pmd_pgtable(*pmd);
1945 1946

	do {
1947
		err = fn(pte++, token, addr, data);
1948 1949
		if (err)
			break;
1950
	} while (addr += PAGE_SIZE, addr != end);
1951

1952 1953
	arch_leave_lazy_mmu_mode();

1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966
	if (mm != &init_mm)
		pte_unmap_unlock(pte-1, ptl);
	return err;
}

static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pmd_t *pmd;
	unsigned long next;
	int err;

A
Andi Kleen 已提交
1967 1968
	BUG_ON(pud_huge(*pud));

1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
		if (err)
			break;
	} while (pmd++, addr = next, addr != end);
	return err;
}

static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pud_t *pud;
	unsigned long next;
	int err;

	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return -ENOMEM;
	do {
		next = pud_addr_end(addr, end);
		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
		if (err)
			break;
	} while (pud++, addr = next, addr != end);
	return err;
}

/*
 * Scan a region of virtual memory, filling in page tables as necessary
 * and calling a provided function on each leaf page table.
 */
int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
			unsigned long size, pte_fn_t fn, void *data)
{
	pgd_t *pgd;
	unsigned long next;
2010
	unsigned long end = addr + size;
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
	int err;

	BUG_ON(addr >= end);
	pgd = pgd_offset(mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
2021

2022 2023 2024 2025
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

2026 2027 2028 2029 2030 2031 2032 2033 2034
/*
 * handle_pte_fault chooses page fault handler according to an entry
 * which was read non-atomically.  Before making any commitment, on
 * those architectures or configurations (e.g. i386 with PAE) which
 * might give a mix of unmatched parts, do_swap_page and do_file_page
 * must check under lock before unmapping the pte and proceeding
 * (but do_wp_page is only called after already making such a check;
 * and do_anonymous_page and do_no_page can safely check later on).
 */
H
Hugh Dickins 已提交
2035
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2036 2037 2038 2039 2040
				pte_t *page_table, pte_t orig_pte)
{
	int same = 1;
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
	if (sizeof(pte_t) > sizeof(unsigned long)) {
H
Hugh Dickins 已提交
2041 2042
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
2043
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
2044
		spin_unlock(ptl);
2045 2046 2047 2048 2049 2050
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063
/*
 * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
 * servicing faults for write access.  In the normal case, do always want
 * pte_mkwrite.  But get_user_pages can cause write faults for mappings
 * that do not have writing enabled, when used by access_process_vm.
 */
static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
{
	if (likely(vma->vm_flags & VM_WRITE))
		pte = pte_mkwrite(pte);
	return pte;
}

2064
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2065 2066 2067 2068 2069 2070 2071 2072 2073
{
	/*
	 * If the source page was a PFN mapping, we don't have
	 * a "struct page" for it. We do a best-effort copy by
	 * just copying from the original user address. If that
	 * fails, we just zero-fill it. Live with it.
	 */
	if (unlikely(!src)) {
		void *kaddr = kmap_atomic(dst, KM_USER0);
L
Linus Torvalds 已提交
2074 2075 2076 2077 2078 2079 2080 2081 2082
		void __user *uaddr = (void __user *)(va & PAGE_MASK);

		/*
		 * This really shouldn't fail, because the page is there
		 * in the page tables. But it might just be unreadable,
		 * in which case we just give up and fill the result with
		 * zeroes.
		 */
		if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2083 2084
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
2085
		flush_dcache_page(dst);
N
Nick Piggin 已提交
2086 2087
	} else
		copy_user_highpage(dst, src, va, vma);
2088 2089
}

L
Linus Torvalds 已提交
2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103
/*
 * This routine handles present pages, when users try to write
 * to a shared page. It is done by copying the page to a new address
 * and decrementing the shared-page counter for the old page.
 *
 * Note that this routine assumes that the protection checks have been
 * done by the caller (the low-level page fault routine in most cases).
 * Thus we can safely just mark it writable once we've done any necessary
 * COW.
 *
 * We also mark the page dirty at this point even though the page will
 * change only once the write actually happens. This avoids a few races,
 * and potentially makes it more efficient.
 *
2104 2105 2106
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), with pte both mapped and locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2107
 */
2108 2109
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2110
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
2111
{
2112
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
2113
	pte_t entry;
N
Nick Piggin 已提交
2114
	int reuse = 0, ret = 0;
2115
	int page_mkwrite = 0;
2116
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
2117

2118
	old_page = vm_normal_page(vma, address, orig_pte);
2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129
	if (!old_page) {
		/*
		 * VM_MIXEDMAP !pfn_valid() case
		 *
		 * We should not cow pages in a shared writeable mapping.
		 * Just mark the pages writable as we can't do any dirty
		 * accounting on raw pfn maps.
		 */
		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
				     (VM_WRITE|VM_SHARED))
			goto reuse;
2130
		goto gotten;
2131
	}
L
Linus Torvalds 已提交
2132

2133
	/*
P
Peter Zijlstra 已提交
2134 2135
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2136
	 */
H
Hugh Dickins 已提交
2137
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149
		if (!trylock_page(old_page)) {
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);
			lock_page(old_page);
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				page_cache_release(old_page);
				goto unlock;
			}
			page_cache_release(old_page);
P
Peter Zijlstra 已提交
2150
		}
2151
		reuse = reuse_swap_page(old_page);
2152 2153 2154 2155 2156 2157 2158
		if (reuse)
			/*
			 * The page is all ours.  Move it to our anon_vma so
			 * the rmap code will not search our parent or siblings.
			 * Protected against the rmap code by the page lock.
			 */
			page_move_anon_rmap(old_page, vma, address);
2159
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2160
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2161
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
2162 2163 2164 2165 2166
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
2167
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2168 2169 2170 2171 2172 2173 2174 2175 2176
			struct vm_fault vmf;
			int tmp;

			vmf.virtual_address = (void __user *)(address &
								PAGE_MASK);
			vmf.pgoff = old_page->index;
			vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
			vmf.page = old_page;

2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187
			/*
			 * Notify the address space that the page is about to
			 * become writable so that it can prohibit this or wait
			 * for the page to get into an appropriate state.
			 *
			 * We do this without the lock held, so that it can
			 * sleep if it needs to.
			 */
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);

2188 2189 2190 2191
			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
			if (unlikely(tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
				ret = tmp;
2192
				goto unwritable_page;
2193
			}
N
Nick Piggin 已提交
2194 2195 2196 2197 2198 2199 2200 2201 2202
			if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
				lock_page(old_page);
				if (!old_page->mapping) {
					ret = 0; /* retry the fault */
					unlock_page(old_page);
					goto unwritable_page;
				}
			} else
				VM_BUG_ON(!PageLocked(old_page));
2203 2204 2205 2206 2207 2208 2209 2210 2211

			/*
			 * Since we dropped the lock we need to revalidate
			 * the PTE as someone else may have changed it.  If
			 * they did, we just return, as we can count on the
			 * MMU to tell us if they didn't also make it writable.
			 */
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
N
Nick Piggin 已提交
2212 2213 2214
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				page_cache_release(old_page);
2215
				goto unlock;
N
Nick Piggin 已提交
2216
			}
2217 2218

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2219
		}
2220 2221
		dirty_page = old_page;
		get_page(dirty_page);
2222 2223 2224 2225
		reuse = 1;
	}

	if (reuse) {
2226
reuse:
2227 2228 2229
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2230
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2231
			update_mmu_cache(vma, address, page_table);
2232 2233
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
2234 2235 2236 2237 2238
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2239
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2240
gotten:
2241
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2242 2243

	if (unlikely(anon_vma_prepare(vma)))
2244
		goto oom;
H
Hugh Dickins 已提交
2245

H
Hugh Dickins 已提交
2246
	if (is_zero_pfn(pte_pfn(orig_pte))) {
H
Hugh Dickins 已提交
2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257
		new_page = alloc_zeroed_user_highpage_movable(vma, address);
		if (!new_page)
			goto oom;
	} else {
		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
		if (!new_page)
			goto oom;
		cow_user_page(new_page, old_page, address, vma);
	}
	__SetPageUptodate(new_page);

N
Nick Piggin 已提交
2258 2259 2260 2261
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
2262
	if ((vma->vm_flags & VM_LOCKED) && old_page) {
N
Nick Piggin 已提交
2263 2264 2265 2266
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
2267

K
KAMEZAWA Hiroyuki 已提交
2268
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2269 2270
		goto oom_free_new;

L
Linus Torvalds 已提交
2271 2272 2273
	/*
	 * Re-check the pte - we dropped the lock
	 */
2274
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2275
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2276 2277
		if (old_page) {
			if (!PageAnon(old_page)) {
2278 2279
				dec_mm_counter_fast(mm, MM_FILEPAGES);
				inc_mm_counter_fast(mm, MM_ANONPAGES);
H
Hugh Dickins 已提交
2280 2281
			}
		} else
2282
			inc_mm_counter_fast(mm, MM_ANONPAGES);
2283
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2284 2285
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2286 2287 2288 2289 2290 2291
		/*
		 * Clear the pte entry and flush it first, before updating the
		 * pte with the new entry. This will avoid a race condition
		 * seen in the presence of one thread doing SMC and another
		 * thread doing COW.
		 */
2292
		ptep_clear_flush(vma, address, page_table);
N
Nick Piggin 已提交
2293
		page_add_new_anon_rmap(new_page, vma, address);
2294 2295 2296 2297 2298 2299
		/*
		 * We call the notify macro here because, when using secondary
		 * mmu page tables (such as kvm shadow page tables), we want the
		 * new page to be mapped directly into the secondary page table.
		 */
		set_pte_at_notify(mm, address, page_table, entry);
2300
		update_mmu_cache(vma, address, page_table);
N
Nick Piggin 已提交
2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323
		if (old_page) {
			/*
			 * Only after switching the pte to the new page may
			 * we remove the mapcount here. Otherwise another
			 * process may come and find the rmap count decremented
			 * before the pte is switched to the new page, and
			 * "reuse" the old page writing into it while our pte
			 * here still points into it and can be read by other
			 * threads.
			 *
			 * The critical issue is to order this
			 * page_remove_rmap with the ptp_clear_flush above.
			 * Those stores are ordered by (if nothing else,)
			 * the barrier present in the atomic_add_negative
			 * in page_remove_rmap.
			 *
			 * Then the TLB flush in ptep_clear_flush ensures that
			 * no process can access the old page before the
			 * decremented mapcount is visible. And the old page
			 * cannot be reused until after the decremented
			 * mapcount is visible. So transitively, TLBs to
			 * old page will be flushed before it can be reused.
			 */
2324
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2325 2326
		}

L
Linus Torvalds 已提交
2327 2328
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2329
		ret |= VM_FAULT_WRITE;
2330 2331 2332
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2333 2334 2335 2336
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
2337
unlock:
2338
	pte_unmap_unlock(page_table, ptl);
2339
	if (dirty_page) {
2340 2341 2342 2343 2344 2345 2346 2347
		/*
		 * Yes, Virginia, this is actually required to prevent a race
		 * with clear_page_dirty_for_io() from clearing the page dirty
		 * bit after it clear all dirty ptes, but before a racing
		 * do_wp_page installs a dirty pte.
		 *
		 * do_no_page is protected similarly.
		 */
N
Nick Piggin 已提交
2348 2349 2350 2351
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
			set_page_dirty_balance(dirty_page, page_mkwrite);
		}
2352
		put_page(dirty_page);
N
Nick Piggin 已提交
2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370
		if (page_mkwrite) {
			struct address_space *mapping = dirty_page->mapping;

			set_page_dirty(dirty_page);
			unlock_page(dirty_page);
			page_cache_release(dirty_page);
			if (mapping)	{
				/*
				 * Some device drivers do not set page.mapping
				 * but still dirty their pages
				 */
				balance_dirty_pages_ratelimited(mapping);
			}
		}

		/* file_update_time outside page_lock */
		if (vma->vm_file)
			file_update_time(vma->vm_file);
2371
	}
N
Nick Piggin 已提交
2372
	return ret;
2373
oom_free_new:
2374
	page_cache_release(new_page);
2375
oom:
N
Nick Piggin 已提交
2376 2377 2378 2379 2380
	if (old_page) {
		if (page_mkwrite) {
			unlock_page(old_page);
			page_cache_release(old_page);
		}
H
Hugh Dickins 已提交
2381
		page_cache_release(old_page);
N
Nick Piggin 已提交
2382
	}
L
Linus Torvalds 已提交
2383
	return VM_FAULT_OOM;
2384 2385 2386

unwritable_page:
	page_cache_release(old_page);
2387
	return ret;
L
Linus Torvalds 已提交
2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414
}

/*
 * Helper functions for unmap_mapping_range().
 *
 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
 *
 * We have to restart searching the prio_tree whenever we drop the lock,
 * since the iterator is only valid while the lock is held, and anyway
 * a later vma might be split and reinserted earlier while lock dropped.
 *
 * The list of nonlinear vmas could be handled more efficiently, using
 * a placeholder, but handle it in the same way until a need is shown.
 * It is important to search the prio_tree before nonlinear list: a vma
 * may become nonlinear and be shifted from prio_tree to nonlinear list
 * while the lock is dropped; but never shifted from list to prio_tree.
 *
 * In order to make forward progress despite restarting the search,
 * vm_truncate_count is used to mark a vma as now dealt with, so we can
 * quickly skip it next time around.  Since the prio_tree search only
 * shows us those vmas affected by unmapping the range in question, we
 * can't efficiently keep all vmas in step with mapping->truncate_count:
 * so instead reset them all whenever it wraps back to 0 (then go to 1).
 * mapping->truncate_count and vma->vm_truncate_count are protected by
 * i_mmap_lock.
 *
 * In order to make forward progress despite repeatedly restarting some
2415
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441
 * and restart from that address when we reach that vma again.  It might
 * have been split or merged, shrunk or extended, but never shifted: so
 * restart_addr remains valid so long as it remains in the vma's range.
 * unmap_mapping_range forces truncate_count to leap over page-aligned
 * values so we can save vma's restart_addr in its truncate_count field.
 */
#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))

static void reset_vma_truncate_counts(struct address_space *mapping)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;

	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
		vma->vm_truncate_count = 0;
	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
		vma->vm_truncate_count = 0;
}

static int unmap_mapping_range_vma(struct vm_area_struct *vma,
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
	unsigned long restart_addr;
	int need_break;

2442 2443
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2444
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2445 2446
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2447 2448
	 */

L
Linus Torvalds 已提交
2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459
again:
	restart_addr = vma->vm_truncate_count;
	if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
		start_addr = restart_addr;
		if (start_addr >= end_addr) {
			/* Top of vma has been split off since last time */
			vma->vm_truncate_count = details->truncate_count;
			return 0;
		}
	}

2460 2461
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2462
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2463

2464
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2465 2466 2467 2468 2469 2470
		/* We have now completed this vma: mark it so */
		vma->vm_truncate_count = details->truncate_count;
		if (!need_break)
			return 0;
	} else {
		/* Note restart_addr in vma's truncate_count field */
2471
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537
		if (!need_break)
			goto again;
	}

	spin_unlock(details->i_mmap_lock);
	cond_resched();
	spin_lock(details->i_mmap_lock);
	return -EINTR;
}

static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;
	pgoff_t vba, vea, zba, zea;

restart:
	vma_prio_tree_foreach(vma, &iter, root,
			details->first_index, details->last_index) {
		/* Skip quickly over those we have already dealt with */
		if (vma->vm_truncate_count == details->truncate_count)
			continue;

		vba = vma->vm_pgoff;
		vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
		/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
		zba = details->first_index;
		if (zba < vba)
			zba = vba;
		zea = details->last_index;
		if (zea > vea)
			zea = vea;

		if (unmap_mapping_range_vma(vma,
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
				details) < 0)
			goto restart;
	}
}

static inline void unmap_mapping_range_list(struct list_head *head,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;

	/*
	 * In nonlinear VMAs there is no correspondence between virtual address
	 * offset and file offset.  So we must perform an exhaustive search
	 * across *all* the pages in each nonlinear VMA, not just the pages
	 * whose virtual address lies outside the file truncation point.
	 */
restart:
	list_for_each_entry(vma, head, shared.vm_set.list) {
		/* Skip quickly over those we have already dealt with */
		if (vma->vm_truncate_count == details->truncate_count)
			continue;
		details->nonlinear_vma = vma;
		if (unmap_mapping_range_vma(vma, vma->vm_start,
					vma->vm_end, details) < 0)
			goto restart;
	}
}

/**
2538
 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
M
Martin Waitz 已提交
2539
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2540 2541
 * @holebegin: byte in first page to unmap, relative to the start of
 * the underlying file.  This will be rounded down to a PAGE_SIZE
N
npiggin@suse.de 已提交
2542
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575
 * must keep the partial page.  In contrast, we must get rid of
 * partial pages.
 * @holelen: size of prospective hole in bytes.  This will be rounded
 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
 * end of the file.
 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
 * but 0 when invalidating pagecache, don't throw away private data.
 */
void unmap_mapping_range(struct address_space *mapping,
		loff_t const holebegin, loff_t const holelen, int even_cows)
{
	struct zap_details details;
	pgoff_t hba = holebegin >> PAGE_SHIFT;
	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;

	/* Check for overflow. */
	if (sizeof(holelen) > sizeof(hlen)) {
		long long holeend =
			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
		if (holeend & ~(long long)ULONG_MAX)
			hlen = ULONG_MAX - hba + 1;
	}

	details.check_mapping = even_cows? NULL: mapping;
	details.nonlinear_vma = NULL;
	details.first_index = hba;
	details.last_index = hba + hlen - 1;
	if (details.last_index < details.first_index)
		details.last_index = ULONG_MAX;
	details.i_mmap_lock = &mapping->i_mmap_lock;

	spin_lock(&mapping->i_mmap_lock);

2576
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592
	mapping->truncate_count++;
	if (unlikely(is_restart_addr(mapping->truncate_count))) {
		if (mapping->truncate_count == 0)
			reset_vma_truncate_counts(mapping);
		mapping->truncate_count++;
	}
	details.truncate_count = mapping->truncate_count;

	if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
	spin_unlock(&mapping->i_mmap_lock);
}
EXPORT_SYMBOL(unmap_mapping_range);

2593 2594 2595 2596 2597 2598 2599 2600 2601
int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
{
	struct address_space *mapping = inode->i_mapping;

	/*
	 * If the underlying filesystem is not going to provide
	 * a way to truncate a range of blocks (punch a hole) -
	 * we should return failure right now.
	 */
A
Al Viro 已提交
2602
	if (!inode->i_op->truncate_range)
2603 2604
		return -ENOSYS;

2605
	mutex_lock(&inode->i_mutex);
2606 2607 2608
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2609
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2610 2611
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2612
	mutex_unlock(&inode->i_mutex);
2613 2614 2615 2616

	return 0;
}

L
Linus Torvalds 已提交
2617
/*
2618 2619 2620
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2621
 */
2622 2623
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2624
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2625
{
2626
	spinlock_t *ptl;
A
Andrea Arcangeli 已提交
2627
	struct page *page, *swapcache = NULL;
2628
	swp_entry_t entry;
L
Linus Torvalds 已提交
2629
	pte_t pte;
2630
	int locked;
2631
	struct mem_cgroup *ptr = NULL;
2632
	int exclusive = 0;
N
Nick Piggin 已提交
2633
	int ret = 0;
L
Linus Torvalds 已提交
2634

H
Hugh Dickins 已提交
2635
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2636
		goto out;
2637 2638

	entry = pte_to_swp_entry(orig_pte);
2639 2640 2641 2642 2643 2644 2645
	if (unlikely(non_swap_entry(entry))) {
		if (is_migration_entry(entry)) {
			migration_entry_wait(mm, pmd, address);
		} else if (is_hwpoison_entry(entry)) {
			ret = VM_FAULT_HWPOISON;
		} else {
			print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
2646
			ret = VM_FAULT_SIGBUS;
2647
		}
2648 2649
		goto out;
	}
2650
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2651 2652
	page = lookup_swap_cache(entry);
	if (!page) {
H
Hugh Dickins 已提交
2653
		grab_swap_token(mm); /* Contend for token _before_ read-in */
2654 2655
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2656 2657
		if (!page) {
			/*
2658 2659
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2660
			 */
2661
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2662 2663
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2664
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2665
			goto unlock;
L
Linus Torvalds 已提交
2666 2667 2668 2669
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2670
		count_vm_event(PGMAJFAULT);
2671
	} else if (PageHWPoison(page)) {
2672 2673 2674 2675
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2676 2677
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2678
		goto out_release;
L
Linus Torvalds 已提交
2679 2680
	}

2681
	locked = lock_page_or_retry(page, mm, flags);
2682
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2683 2684 2685 2686
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2687

A
Andrea Arcangeli 已提交
2688
	/*
2689 2690 2691 2692
	 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
	 * release the swapcache from under us.  The page pin, and pte_same
	 * test below, are not enough to exclude that.  Even if it is still
	 * swapcache, we need to check that the page's swap has not changed.
A
Andrea Arcangeli 已提交
2693
	 */
2694
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706
		goto out_page;

	if (ksm_might_need_to_copy(page, vma, address)) {
		swapcache = page;
		page = ksm_does_need_to_copy(page, vma, address);

		if (unlikely(!page)) {
			ret = VM_FAULT_OOM;
			page = swapcache;
			swapcache = NULL;
			goto out_page;
		}
H
Hugh Dickins 已提交
2707 2708
	}

K
KAMEZAWA Hiroyuki 已提交
2709
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2710
		ret = VM_FAULT_OOM;
2711
		goto out_page;
2712 2713
	}

L
Linus Torvalds 已提交
2714
	/*
2715
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2716
	 */
2717
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2718
	if (unlikely(!pte_same(*page_table, orig_pte)))
2719 2720 2721 2722 2723
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2724 2725
	}

2726 2727 2728 2729 2730 2731 2732 2733
	/*
	 * The page isn't present yet, go ahead with the fault.
	 *
	 * Be careful about the sequence of operations here.
	 * To get its accounting right, reuse_swap_page() must be called
	 * while the page is counted on swap but not yet in mapcount i.e.
	 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
	 * must be called after the swap_free(), or it will never succeed.
2734 2735 2736 2737
	 * Because delete_from_swap_page() may be called by reuse_swap_page(),
	 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
	 * in page->private. In this case, a record in swap_cgroup  is silently
	 * discarded at swap_free().
2738
	 */
L
Linus Torvalds 已提交
2739

2740
	inc_mm_counter_fast(mm, MM_ANONPAGES);
K
KAMEZAWA Hiroyuki 已提交
2741
	dec_mm_counter_fast(mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
2742
	pte = mk_pte(page, vma->vm_page_prot);
2743
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2744
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2745
		flags &= ~FAULT_FLAG_WRITE;
2746
		ret |= VM_FAULT_WRITE;
2747
		exclusive = 1;
L
Linus Torvalds 已提交
2748 2749 2750
	}
	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
2751
	do_page_add_anon_rmap(page, vma, address, exclusive);
2752 2753
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
2754

2755
	swap_free(entry);
N
Nick Piggin 已提交
2756
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2757
		try_to_free_swap(page);
2758
	unlock_page(page);
A
Andrea Arcangeli 已提交
2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770
	if (swapcache) {
		/*
		 * Hold the lock to avoid the swap entry to be reused
		 * until we take the PT lock for the pte_same() check
		 * (to avoid false positives from pte_same). For
		 * further safety release the lock after the swap_free
		 * so that the swap count won't change under a
		 * parallel locked swapcache.
		 */
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
2771

2772
	if (flags & FAULT_FLAG_WRITE) {
2773 2774 2775
		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
		if (ret & VM_FAULT_ERROR)
			ret &= VM_FAULT_ERROR;
L
Linus Torvalds 已提交
2776 2777 2778 2779
		goto out;
	}

	/* No need to invalidate - it was non-present before */
2780
	update_mmu_cache(vma, address, page_table);
2781
unlock:
2782
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2783 2784
out:
	return ret;
2785
out_nomap:
2786
	mem_cgroup_cancel_charge_swapin(ptr);
2787
	pte_unmap_unlock(page_table, ptl);
2788
out_page:
2789
	unlock_page(page);
2790
out_release:
2791
	page_cache_release(page);
A
Andrea Arcangeli 已提交
2792 2793 2794 2795
	if (swapcache) {
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
2796
	return ret;
L
Linus Torvalds 已提交
2797 2798
}

2799
/*
2800 2801
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2802 2803 2804 2805 2806 2807
 * doesn't hit another vma.
 */
static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
{
	address &= PAGE_MASK;
	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2808 2809 2810 2811 2812 2813 2814 2815 2816 2817
		struct vm_area_struct *prev = vma->vm_prev;

		/*
		 * Is there a mapping abutting this one below?
		 *
		 * That's only ok if it's the same stack mapping
		 * that has gotten split..
		 */
		if (prev && prev->vm_end == address)
			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2818

2819
		expand_stack(vma, address - PAGE_SIZE);
2820
	}
2821 2822 2823 2824 2825 2826 2827 2828 2829
	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
		struct vm_area_struct *next = vma->vm_next;

		/* As VM_GROWSDOWN but s/below/above/ */
		if (next && next->vm_start == address + PAGE_SIZE)
			return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;

		expand_upwards(vma, address + PAGE_SIZE);
	}
2830 2831 2832
	return 0;
}

L
Linus Torvalds 已提交
2833
/*
2834 2835 2836
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2837
 */
2838 2839
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2840
		unsigned int flags)
L
Linus Torvalds 已提交
2841
{
2842 2843
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2844 2845
	pte_t entry;

2846 2847 2848 2849
	pte_unmap(page_table);

	/* Check if we need to add a guard page to the stack */
	if (check_stack_guard_page(vma, address) < 0)
2850 2851
		return VM_FAULT_SIGBUS;

2852
	/* Use the zero-page for reads */
H
Hugh Dickins 已提交
2853 2854 2855
	if (!(flags & FAULT_FLAG_WRITE)) {
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
2856
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2857 2858 2859 2860 2861
		if (!pte_none(*page_table))
			goto unlock;
		goto setpte;
	}

N
Nick Piggin 已提交
2862 2863 2864 2865 2866 2867
	/* Allocate our own private page. */
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
	page = alloc_zeroed_user_highpage_movable(vma, address);
	if (!page)
		goto oom;
N
Nick Piggin 已提交
2868
	__SetPageUptodate(page);
2869

K
KAMEZAWA Hiroyuki 已提交
2870
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2871 2872
		goto oom_free_page;

N
Nick Piggin 已提交
2873
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
2874 2875
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
2876

N
Nick Piggin 已提交
2877
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2878
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
2879
		goto release;
H
Hugh Dickins 已提交
2880

2881
	inc_mm_counter_fast(mm, MM_ANONPAGES);
N
Nick Piggin 已提交
2882
	page_add_new_anon_rmap(page, vma, address);
H
Hugh Dickins 已提交
2883
setpte:
2884
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2885 2886

	/* No need to invalidate - it was non-present before */
2887
	update_mmu_cache(vma, address, page_table);
2888
unlock:
2889
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2890
	return 0;
2891
release:
2892
	mem_cgroup_uncharge_page(page);
2893 2894
	page_cache_release(page);
	goto unlock;
2895
oom_free_page:
2896
	page_cache_release(page);
2897
oom:
L
Linus Torvalds 已提交
2898 2899 2900 2901
	return VM_FAULT_OOM;
}

/*
2902
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2903
 * tries to share with existing pages, but makes a separate copy if
2904 2905
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2906 2907 2908 2909
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2910
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2911
 * but allow concurrent faults), and pte neither mapped nor locked.
2912
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2913
 */
2914
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2915
		unsigned long address, pmd_t *pmd,
2916
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2917
{
2918
	pte_t *page_table;
2919
	spinlock_t *ptl;
N
Nick Piggin 已提交
2920
	struct page *page;
L
Linus Torvalds 已提交
2921 2922
	pte_t entry;
	int anon = 0;
2923
	int charged = 0;
2924
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2925 2926
	struct vm_fault vmf;
	int ret;
2927
	int page_mkwrite = 0;
2928

N
Nick Piggin 已提交
2929 2930 2931 2932
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2933

N
Nick Piggin 已提交
2934
	ret = vma->vm_ops->fault(vma, &vmf);
2935 2936
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
			    VM_FAULT_RETRY)))
N
Nick Piggin 已提交
2937
		return ret;
L
Linus Torvalds 已提交
2938

2939 2940 2941 2942 2943 2944
	if (unlikely(PageHWPoison(vmf.page))) {
		if (ret & VM_FAULT_LOCKED)
			unlock_page(vmf.page);
		return VM_FAULT_HWPOISON;
	}

2945
	/*
N
Nick Piggin 已提交
2946
	 * For consistency in subsequent calls, make the faulted page always
2947 2948
	 * locked.
	 */
N
Nick Piggin 已提交
2949
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2950
		lock_page(vmf.page);
2951
	else
N
Nick Piggin 已提交
2952
		VM_BUG_ON(!PageLocked(vmf.page));
2953

L
Linus Torvalds 已提交
2954 2955 2956
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2957
	page = vmf.page;
2958
	if (flags & FAULT_FLAG_WRITE) {
2959
		if (!(vma->vm_flags & VM_SHARED)) {
2960
			anon = 1;
2961
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2962
				ret = VM_FAULT_OOM;
2963
				goto out;
2964
			}
N
Nick Piggin 已提交
2965 2966
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2967
			if (!page) {
N
Nick Piggin 已提交
2968
				ret = VM_FAULT_OOM;
2969
				goto out;
2970
			}
K
KAMEZAWA Hiroyuki 已提交
2971
			if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2972 2973 2974 2975 2976
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
2977 2978 2979 2980 2981 2982
			/*
			 * Don't let another task, with possibly unlocked vma,
			 * keep the mlocked page.
			 */
			if (vma->vm_flags & VM_LOCKED)
				clear_page_mlock(vmf.page);
N
Nick Piggin 已提交
2983
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2984
			__SetPageUptodate(page);
2985
		} else {
2986 2987
			/*
			 * If the page will be shareable, see if the backing
2988
			 * address space wants to know that the page is about
2989 2990
			 * to become writable
			 */
2991
			if (vma->vm_ops->page_mkwrite) {
2992 2993
				int tmp;

2994
				unlock_page(page);
N
Nick Piggin 已提交
2995
				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2996 2997 2998 2999
				tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
				if (unlikely(tmp &
					  (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
					ret = tmp;
N
Nick Piggin 已提交
3000
					goto unwritable_page;
N
Nick Piggin 已提交
3001
				}
N
Nick Piggin 已提交
3002 3003 3004 3005 3006 3007 3008 3009 3010
				if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
					lock_page(page);
					if (!page->mapping) {
						ret = 0; /* retry the fault */
						unlock_page(page);
						goto unwritable_page;
					}
				} else
					VM_BUG_ON(!PageLocked(page));
3011
				page_mkwrite = 1;
3012 3013
			}
		}
3014

L
Linus Torvalds 已提交
3015 3016
	}

3017
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
3018 3019 3020 3021 3022 3023

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
3024
	 * Note that if FAULT_FLAG_WRITE is set, we either now have
L
Linus Torvalds 已提交
3025 3026 3027 3028 3029
	 * an exclusive copy of the page, or this is a shared mapping,
	 * so we can make it writable and dirty to avoid having to
	 * handle that later.
	 */
	/* Only go through if we didn't race with anybody else... */
3030
	if (likely(pte_same(*page_table, orig_pte))) {
3031 3032
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
3033
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
3034 3035
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
3036
			inc_mm_counter_fast(mm, MM_ANONPAGES);
3037
			page_add_new_anon_rmap(page, vma, address);
3038
		} else {
3039
			inc_mm_counter_fast(mm, MM_FILEPAGES);
3040
			page_add_file_rmap(page);
3041
			if (flags & FAULT_FLAG_WRITE) {
3042
				dirty_page = page;
3043 3044
				get_page(dirty_page);
			}
3045
		}
3046
		set_pte_at(mm, address, page_table, entry);
3047 3048

		/* no need to invalidate: a not-present page won't be cached */
3049
		update_mmu_cache(vma, address, page_table);
L
Linus Torvalds 已提交
3050
	} else {
3051 3052
		if (charged)
			mem_cgroup_uncharge_page(page);
3053 3054 3055
		if (anon)
			page_cache_release(page);
		else
3056
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
3057 3058
	}

3059
	pte_unmap_unlock(page_table, ptl);
3060 3061

out:
N
Nick Piggin 已提交
3062 3063
	if (dirty_page) {
		struct address_space *mapping = page->mapping;
3064

N
Nick Piggin 已提交
3065 3066 3067
		if (set_page_dirty(dirty_page))
			page_mkwrite = 1;
		unlock_page(dirty_page);
3068
		put_page(dirty_page);
N
Nick Piggin 已提交
3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083
		if (page_mkwrite && mapping) {
			/*
			 * Some device drivers do not set page.mapping but still
			 * dirty their pages
			 */
			balance_dirty_pages_ratelimited(mapping);
		}

		/* file_update_time outside page_lock */
		if (vma->vm_file)
			file_update_time(vma->vm_file);
	} else {
		unlock_page(vmf.page);
		if (anon)
			page_cache_release(vmf.page);
3084
	}
3085

N
Nick Piggin 已提交
3086
	return ret;
N
Nick Piggin 已提交
3087 3088 3089 3090

unwritable_page:
	page_cache_release(page);
	return ret;
3091
}
3092

3093 3094
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3095
		unsigned int flags, pte_t orig_pte)
3096 3097
{
	pgoff_t pgoff = (((address & PAGE_MASK)
3098
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3099

3100 3101
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3102 3103
}

L
Linus Torvalds 已提交
3104 3105 3106 3107
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
3108 3109 3110 3111
 *
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
3112
 */
N
Nick Piggin 已提交
3113
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3114
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3115
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3116
{
3117
	pgoff_t pgoff;
L
Linus Torvalds 已提交
3118

3119 3120
	flags |= FAULT_FLAG_NONLINEAR;

H
Hugh Dickins 已提交
3121
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
3122
		return 0;
L
Linus Torvalds 已提交
3123

3124
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3125 3126 3127
		/*
		 * Page table corrupted: show pte and kill process.
		 */
3128
		print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
3129
		return VM_FAULT_SIGBUS;
3130 3131 3132
	}

	pgoff = pte_to_pgoff(orig_pte);
3133
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144
}

/*
 * These routines also need to handle stuff like marking pages dirty
 * and/or accessed for architectures that don't do it in hardware (most
 * RISC architectures).  The early dirtying is also good on the i386.
 *
 * There is also a hook called "update_mmu_cache()" that architectures
 * with external mmu caches can use to update those (ie the Sparc or
 * PowerPC hashed page tables that act as extended TLBs).
 *
H
Hugh Dickins 已提交
3145 3146 3147
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
3148 3149
 */
static inline int handle_pte_fault(struct mm_struct *mm,
3150
		struct vm_area_struct *vma, unsigned long address,
3151
		pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
3152 3153
{
	pte_t entry;
3154
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3155

3156
	entry = *pte;
L
Linus Torvalds 已提交
3157
	if (!pte_present(entry)) {
3158
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
3159
			if (vma->vm_ops) {
N
Nick Piggin 已提交
3160
				if (likely(vma->vm_ops->fault))
3161
					return do_linear_fault(mm, vma, address,
3162
						pte, pmd, flags, entry);
J
Jes Sorensen 已提交
3163 3164
			}
			return do_anonymous_page(mm, vma, address,
3165
						 pte, pmd, flags);
3166
		}
L
Linus Torvalds 已提交
3167
		if (pte_file(entry))
N
Nick Piggin 已提交
3168
			return do_nonlinear_fault(mm, vma, address,
3169
					pte, pmd, flags, entry);
3170
		return do_swap_page(mm, vma, address,
3171
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
3172 3173
	}

H
Hugh Dickins 已提交
3174
	ptl = pte_lockptr(mm, pmd);
3175 3176 3177
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
3178
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3179
		if (!pte_write(entry))
3180 3181
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
3182 3183 3184
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
3185
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3186
		update_mmu_cache(vma, address, pte);
3187 3188 3189 3190 3191 3192 3193
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
3194
		if (flags & FAULT_FLAG_WRITE)
3195
			flush_tlb_fix_spurious_fault(vma, address);
3196
	}
3197 3198
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3199
	return 0;
L
Linus Torvalds 已提交
3200 3201 3202 3203 3204
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
3205
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3206
		unsigned long address, unsigned int flags)
L
Linus Torvalds 已提交
3207 3208 3209 3210 3211 3212 3213 3214
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

3215
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
3216

3217 3218 3219
	/* do counter updates before entering really critical section. */
	check_sync_rss_stat(current);

3220
	if (unlikely(is_vm_hugetlb_page(vma)))
3221
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3222 3223 3224 3225

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3226
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3227 3228
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3229
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3230 3231
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
3232
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3233

3234
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3235 3236 3237 3238 3239
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3240
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3241
 */
3242
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3243
{
H
Hugh Dickins 已提交
3244 3245
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3246
		return -ENOMEM;
L
Linus Torvalds 已提交
3247

3248 3249
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3250
	spin_lock(&mm->page_table_lock);
3251
	if (pgd_present(*pgd))		/* Another has populated it */
3252
		pud_free(mm, new);
3253 3254
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3255
	spin_unlock(&mm->page_table_lock);
3256
	return 0;
L
Linus Torvalds 已提交
3257 3258 3259 3260 3261 3262
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3263
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3264
 */
3265
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3266
{
H
Hugh Dickins 已提交
3267 3268
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3269
		return -ENOMEM;
L
Linus Torvalds 已提交
3270

3271 3272
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3273
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3274
#ifndef __ARCH_HAS_4LEVEL_HACK
3275
	if (pud_present(*pud))		/* Another has populated it */
3276
		pmd_free(mm, new);
3277 3278
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3279
#else
3280
	if (pgd_present(*pud))		/* Another has populated it */
3281
		pmd_free(mm, new);
3282 3283
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3284
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3285
	spin_unlock(&mm->page_table_lock);
3286
	return 0;
3287
}
L
Linus Torvalds 已提交
3288 3289 3290 3291 3292 3293 3294 3295 3296
#endif /* __PAGETABLE_PMD_FOLDED */

int make_pages_present(unsigned long addr, unsigned long end)
{
	int ret, len, write;
	struct vm_area_struct * vma;

	vma = find_vma(current->mm, addr);
	if (!vma)
K
KOSAKI Motohiro 已提交
3297
		return -ENOMEM;
L
Linus Torvalds 已提交
3298
	write = (vma->vm_flags & VM_WRITE) != 0;
3299 3300
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
3301
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
3302 3303
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
3304
	if (ret < 0)
L
Linus Torvalds 已提交
3305
		return ret;
3306
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
3307 3308 3309 3310 3311
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
3312
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
3313 3314 3315 3316 3317 3318

static int __init gate_vma_init(void)
{
	gate_vma.vm_mm = NULL;
	gate_vma.vm_start = FIXADDR_USER_START;
	gate_vma.vm_end = FIXADDR_USER_END;
R
Roland McGrath 已提交
3319 3320
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
3321 3322 3323 3324 3325 3326 3327
	/*
	 * Make sure the vDSO gets into every core dump.
	 * Dumping its contents makes post-mortem fully interpretable later
	 * without matching up the same kernel and hardware config to see
	 * what PC values meant.
	 */
	gate_vma.vm_flags |= VM_ALWAYSDUMP;
L
Linus Torvalds 已提交
3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351
	return 0;
}
__initcall(gate_vma_init);
#endif

struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
#ifdef AT_SYSINFO_EHDR
	return &gate_vma;
#else
	return NULL;
#endif
}

int in_gate_area_no_task(unsigned long addr)
{
#ifdef AT_SYSINFO_EHDR
	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
		return 1;
#endif
	return 0;
}

#endif	/* __HAVE_ARCH_GATE_AREA */
3352

J
Johannes Weiner 已提交
3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389
static int follow_pte(struct mm_struct *mm, unsigned long address,
		pte_t **ptepp, spinlock_t **ptlp)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep;

	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
		goto out;

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
		goto out;

	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
		goto out;

	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
	if (pmd_huge(*pmd))
		goto out;

	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
	if (!ptep)
		goto out;
	if (!pte_present(*ptep))
		goto unlock;
	*ptepp = ptep;
	return 0;
unlock:
	pte_unmap_unlock(ptep, *ptlp);
out:
	return -EINVAL;
}

J
Johannes Weiner 已提交
3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418
/**
 * follow_pfn - look up PFN at a user virtual address
 * @vma: memory mapping
 * @address: user virtual address
 * @pfn: location to store found PFN
 *
 * Only IO mappings and raw PFN mappings are allowed.
 *
 * Returns zero and the pfn at @pfn on success, -ve otherwise.
 */
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
	unsigned long *pfn)
{
	int ret = -EINVAL;
	spinlock_t *ptl;
	pte_t *ptep;

	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		return ret;

	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
	if (ret)
		return ret;
	*pfn = pte_pfn(*ptep);
	pte_unmap_unlock(ptep, ptl);
	return 0;
}
EXPORT_SYMBOL(follow_pfn);

3419
#ifdef CONFIG_HAVE_IOREMAP_PROT
3420 3421 3422
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3423
{
3424
	int ret = -EINVAL;
3425 3426 3427
	pte_t *ptep, pte;
	spinlock_t *ptl;

3428 3429
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3430

3431
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3432
		goto out;
3433
	pte = *ptep;
3434

3435 3436 3437 3438
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3439
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3440

3441
	ret = 0;
3442 3443 3444
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3445
	return ret;
3446 3447 3448 3449 3450 3451 3452
}

int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
			void *buf, int len, int write)
{
	resource_size_t phys_addr;
	unsigned long prot = 0;
K
KOSAKI Motohiro 已提交
3453
	void __iomem *maddr;
3454 3455
	int offset = addr & (PAGE_SIZE-1);

3456
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469
		return -EINVAL;

	maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
	if (write)
		memcpy_toio(maddr + offset, buf, len);
	else
		memcpy_fromio(buf, maddr + offset, len);
	iounmap(maddr);

	return len;
}
#endif

3470 3471 3472 3473 3474 3475 3476 3477 3478 3479 3480 3481 3482 3483 3484 3485
/*
 * Access another process' address space.
 * Source/target buffer must be kernel space,
 * Do not walk the page table directly, use get_user_pages
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct mm_struct *mm;
	struct vm_area_struct *vma;
	void *old_buf = buf;

	mm = get_task_mm(tsk);
	if (!mm)
		return 0;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3486
	/* ignore errors, just check how much was successfully transferred */
3487 3488 3489
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3490
		struct page *page = NULL;
3491 3492 3493

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3494 3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509
		if (ret <= 0) {
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
#ifdef CONFIG_HAVE_IOREMAP_PROT
			vma = find_vma(mm, addr);
			if (!vma)
				break;
			if (vma->vm_ops && vma->vm_ops->access)
				ret = vma->vm_ops->access(vma, addr, buf,
							  len, write);
			if (ret <= 0)
#endif
				break;
			bytes = ret;
3510
		} else {
3511 3512 3513 3514 3515 3516 3517 3518 3519 3520 3521 3522 3523 3524 3525 3526
			bytes = len;
			offset = addr & (PAGE_SIZE-1);
			if (bytes > PAGE_SIZE-offset)
				bytes = PAGE_SIZE-offset;

			maddr = kmap(page);
			if (write) {
				copy_to_user_page(vma, page, addr,
						  maddr + offset, buf, bytes);
				set_page_dirty_lock(page);
			} else {
				copy_from_user_page(vma, page, addr,
						    buf, maddr + offset, bytes);
			}
			kunmap(page);
			page_cache_release(page);
3527 3528 3529 3530 3531 3532 3533 3534 3535 3536
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
3537 3538 3539 3540 3541 3542 3543 3544 3545

/*
 * Print the name of a VMA.
 */
void print_vma_addr(char *prefix, unsigned long ip)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;

3546 3547 3548 3549 3550 3551 3552
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3553 3554 3555 3556 3557 3558 3559 3560
	down_read(&mm->mmap_sem);
	vma = find_vma(mm, ip);
	if (vma && vma->vm_file) {
		struct file *f = vma->vm_file;
		char *buf = (char *)__get_free_page(GFP_KERNEL);
		if (buf) {
			char *p, *s;

3561
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3562 3563 3564 3565 3566 3567 3568 3569 3570 3571 3572 3573 3574
			if (IS_ERR(p))
				p = "?";
			s = strrchr(p, '/');
			if (s)
				p = s+1;
			printk("%s%s[%lx+%lx]", prefix, p,
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
	up_read(&current->mm->mmap_sem);
}
3575 3576 3577 3578

#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
3579 3580 3581 3582 3583 3584 3585 3586 3587
	/*
	 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
	 * holding the mmap_sem, this is safe because kernel memory doesn't
	 * get paged out, therefore we'll never actually fault, and the
	 * below annotations will generate false positives.
	 */
	if (segment_eq(get_fs(), KERNEL_DS))
		return;

3588 3589 3590 3591 3592 3593 3594 3595 3596 3597 3598
	might_sleep();
	/*
	 * it would be nicer only to annotate paths which are not under
	 * pagefault_disable, however that requires a larger audit and
	 * providing helpers like get_user_atomic.
	 */
	if (!in_atomic() && current->mm)
		might_lock_read(&current->mm->mmap_sem);
}
EXPORT_SYMBOL(might_fault);
#endif