memory.c 92.1 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 <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 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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	unsigned long start;

	/*
	 * 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;

	start = addr;
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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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		 */
		anon_vma_unlink(vma);
		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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				anon_vma_unlink(vma);
				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 add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
{
	if (file_rss)
		add_mm_counter(mm, file_rss, file_rss);
	if (anon_rss)
		add_mm_counter(mm, anon_rss, anon_rss);
}

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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));
	if (page) {
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		printk(KERN_ALERT
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		"page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
		page, (void *)page->flags, page_count(page),
		page_mapcount(page), page->mapping, page->index);
	}
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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.
 *
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 */
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#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)
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{
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	unsigned long pfn = pte_pfn(pte);
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	if (HAVE_PTE_SPECIAL) {
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		if (likely(!pte_special(pte)))
			goto check_pfn;
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		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
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		if (!is_zero_pfn(pfn))
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			print_bad_pte(vma, addr, pte, NULL);
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		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

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	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
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			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
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			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
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	}

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	if (is_zero_pfn(pfn))
		return NULL;
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check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
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	/*
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	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
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	 */
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out:
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	return pfn_to_page(pfn);
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}

L
Linus Torvalds 已提交
569 570 571 572 573 574
/*
 * 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
575
static inline unsigned long
L
Linus Torvalds 已提交
576
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
577
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
578
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
579
{
N
Nick Piggin 已提交
580
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
581 582 583 584 585 586
	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)) {
587 588
			swp_entry_t entry = pte_to_swp_entry(pte);

H
Hugh Dickins 已提交
589 590 591
			if (swap_duplicate(entry) < 0)
				return entry.val;

L
Linus Torvalds 已提交
592 593 594
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
595 596 597
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
598 599
				spin_unlock(&mmlist_lock);
			}
600 601 602 603 604 605 606 607 608 609
			if (is_write_migration_entry(entry) &&
					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
610
		}
611
		goto out_set_pte;
L
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612 613 614 615 616 617
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
618
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
619
		ptep_set_wrprotect(src_mm, addr, src_pte);
620
		pte = pte_wrprotect(pte);
L
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621 622 623 624 625 626 627 628 629
	}

	/*
	 * 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);
630 631 632 633

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
H
Hugh Dickins 已提交
634
		page_dup_rmap(page);
635
		rss[PageAnon(page)]++;
636
	}
637 638 639

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
640
	return 0;
L
Linus Torvalds 已提交
641 642 643 644 645 646
}

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)
{
647
	pte_t *orig_src_pte, *orig_dst_pte;
L
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648
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
649
	spinlock_t *src_ptl, *dst_ptl;
650
	int progress = 0;
H
Hugh Dickins 已提交
651
	int rss[2];
H
Hugh Dickins 已提交
652
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
653 654

again:
655
	rss[1] = rss[0] = 0;
H
Hugh Dickins 已提交
656
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
657 658 659
	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
660
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
661
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
662 663
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
664
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
665 666 667 668 669 670

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
671 672 673
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
674
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
675 676
				break;
		}
L
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		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
681 682 683 684
		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
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		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

688
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
689
	spin_unlock(src_ptl);
690
	pte_unmap_nested(orig_src_pte);
691
	add_mm_rss(dst_mm, rss[0], rss[1]);
692
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
693
	cond_resched();
H
Hugh Dickins 已提交
694 695 696 697 698 699

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
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700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755
	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
756
	int ret;
L
Linus Torvalds 已提交
757

758 759 760 761 762 763
	/*
	 * 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.
	 */
764
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
765 766 767 768
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
769 770 771
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

772
	if (unlikely(is_pfn_mapping(vma))) {
773 774 775 776 777 778 779 780 781
		/*
		 * 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
782 783 784 785 786 787 788 789 790 791
	/*
	 * 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
792 793 794 795 796 797
	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
798 799 800 801 802
		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
803
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
804 805 806 807 808

	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
809 810
}

811
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
812
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
813
				unsigned long addr, unsigned long end,
814
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
815
{
N
Nick Piggin 已提交
816
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
817
	pte_t *pte;
818
	spinlock_t *ptl;
819 820
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
821

822
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
823
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
824 825
	do {
		pte_t ptent = *pte;
826 827
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
828
			continue;
829
		}
830 831 832

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
833
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
834
			struct page *page;
835

836
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854
			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
855
			ptent = ptep_get_and_clear_full(mm, addr, pte,
856
							tlb->fullmm);
L
Linus Torvalds 已提交
857 858 859 860 861 862
			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
863
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
864 865
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
866
				anon_rss--;
867 868 869
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
870 871
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
872
					mark_page_accessed(page);
H
Hugh Dickins 已提交
873
				file_rss--;
874
			}
875
			page_remove_rmap(page);
876 877
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
L
Linus Torvalds 已提交
878 879 880 881 882 883 884 885 886
			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;
887 888 889 890 891 892
		if (pte_file(ptent)) {
			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
				print_bad_pte(vma, addr, ptent, NULL);
		} else if
		  (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
			print_bad_pte(vma, addr, ptent, NULL);
893
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
894
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
895

H
Hugh Dickins 已提交
896
	add_mm_rss(mm, file_rss, anon_rss);
897
	arch_leave_lazy_mmu_mode();
898
	pte_unmap_unlock(pte - 1, ptl);
899 900

	return addr;
L
Linus Torvalds 已提交
901 902
}

903
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
904
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
905
				unsigned long addr, unsigned long end,
906
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
907 908 909 910 911 912 913
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
914 915
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
916
			continue;
917 918 919 920 921 922
		}
		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
923 924
}

925
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
926
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
927
				unsigned long addr, unsigned long end,
928
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
929 930 931 932 933 934 935
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
936 937
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
938
			continue;
939 940 941 942 943 944
		}
		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
945 946
}

947 948
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
949
				unsigned long addr, unsigned long end,
950
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
951 952 953 954 955 956 957 958
{
	pgd_t *pgd;
	unsigned long next;

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

	BUG_ON(addr >= end);
959
	mem_cgroup_uncharge_start();
L
Linus Torvalds 已提交
960 961 962 963
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
964 965
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
966
			continue;
967 968 969 970
		}
		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
971
	tlb_end_vma(tlb, vma);
972
	mem_cgroup_uncharge_end();
973 974

	return addr;
L
Linus Torvalds 已提交
975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992
}

#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
 *
993
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
994
 *
995
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
996
 *
997 998
 * 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
999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009
 * 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.
 */
1010
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
1011 1012 1013 1014
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
1015
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1016 1017
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
1018
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
1019
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
1020
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
1021
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1022

A
Andrea Arcangeli 已提交
1023
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036
	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;

1037
		if (unlikely(is_pfn_mapping(vma)))
1038 1039
			untrack_pfn_vma(vma, 0, 0);

L
Linus Torvalds 已提交
1040 1041 1042 1043 1044 1045
		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

1046
			if (unlikely(is_vm_hugetlb_page(vma))) {
1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060
				/*
				 * 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) /
1061
					pages_per_huge_page(hstate_vma(vma));
1062 1063
				}

1064 1065 1066 1067 1068 1069 1070 1071
				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
1072 1073 1074 1075 1076
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
1077
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
1078
				if (i_mmap_lock) {
1079
					*tlbp = NULL;
L
Linus Torvalds 已提交
1080 1081 1082 1083 1084
					goto out;
				}
				cond_resched();
			}

1085
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
1086
			tlb_start_valid = 0;
1087
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1088 1089 1090
		}
	}
out:
A
Andrea Arcangeli 已提交
1091
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1092
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
1093 1094 1095 1096 1097 1098 1099 1100 1101
}

/**
 * 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
 */
1102
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1103 1104 1105 1106 1107 1108 1109 1110 1111
		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);
1112
	update_hiwater_rss(mm);
1113 1114 1115
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
1116
	return end;
L
Linus Torvalds 已提交
1117 1118
}

1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141
/**
 * 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);

L
Linus Torvalds 已提交
1142 1143 1144
/*
 * Do a quick page-table lookup for a single page.
 */
1145
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1146
			unsigned int flags)
L
Linus Torvalds 已提交
1147 1148 1149 1150 1151
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1152
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1153
	struct page *page;
1154
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1155

1156 1157 1158 1159 1160
	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
1161

1162
	page = NULL;
L
Linus Torvalds 已提交
1163 1164
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1165
		goto no_page_table;
L
Linus Torvalds 已提交
1166 1167

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1168
	if (pud_none(*pud))
1169
		goto no_page_table;
A
Andi Kleen 已提交
1170 1171 1172 1173 1174 1175 1176 1177
	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
1178
	pmd = pmd_offset(pud, address);
1179
	if (pmd_none(*pmd))
1180 1181 1182 1183
		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
1184
		goto out;
1185
	}
1186 1187 1188
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1189
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1190 1191

	pte = *ptep;
1192
	if (!pte_present(pte))
1193
		goto no_page;
1194 1195
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
H
Hugh Dickins 已提交
1196

1197
	page = vm_normal_page(vma, address, pte);
H
Hugh Dickins 已提交
1198 1199
	if (unlikely(!page)) {
		if ((flags & FOLL_DUMP) ||
H
Hugh Dickins 已提交
1200
		    !is_zero_pfn(pte_pfn(pte)))
H
Hugh Dickins 已提交
1201 1202 1203
			goto bad_page;
		page = pte_page(pte);
	}
L
Linus Torvalds 已提交
1204

1205 1206 1207 1208 1209 1210
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
1211 1212 1213 1214 1215
		/*
		 * 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().
		 */
1216 1217 1218 1219
		mark_page_accessed(page);
	}
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1220
out:
1221
	return page;
L
Linus Torvalds 已提交
1222

1223 1224 1225 1226 1227 1228 1229 1230
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
1231

1232 1233 1234
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
H
Hugh Dickins 已提交
1235 1236 1237 1238 1239
	 * 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.
1240
	 */
H
Hugh Dickins 已提交
1241 1242 1243
	if ((flags & FOLL_DUMP) &&
	    (!vma->vm_ops || !vma->vm_ops->fault))
		return ERR_PTR(-EFAULT);
1244
	return page;
L
Linus Torvalds 已提交
1245 1246
}

N
Nick Piggin 已提交
1247
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
H
Hugh Dickins 已提交
1248
		     unsigned long start, int nr_pages, unsigned int gup_flags,
1249
		     struct page **pages, struct vm_area_struct **vmas)
L
Linus Torvalds 已提交
1250 1251
{
	int i;
H
Hugh Dickins 已提交
1252
	unsigned long vm_flags;
L
Linus Torvalds 已提交
1253

1254
	if (nr_pages <= 0)
1255
		return 0;
H
Hugh Dickins 已提交
1256 1257 1258

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

L
Linus Torvalds 已提交
1259 1260
	/* 
	 * Require read or write permissions.
H
Hugh Dickins 已提交
1261
	 * If FOLL_FORCE is set, we only require the "MAY" flags.
L
Linus Torvalds 已提交
1262
	 */
H
Hugh Dickins 已提交
1263 1264 1265 1266
	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
1267 1268 1269
	i = 0;

	do {
1270
		struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1271 1272 1273 1274 1275 1276 1277 1278 1279

		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
1280 1281

			/* user gate pages are read-only */
H
Hugh Dickins 已提交
1282
			if (gup_flags & FOLL_WRITE)
L
Linus Torvalds 已提交
1283 1284 1285 1286 1287 1288 1289 1290 1291
				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);
1292 1293
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1294
			pte = pte_offset_map(pmd, pg);
1295 1296 1297 1298
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1299
			if (pages) {
1300
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1301 1302 1303
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1304 1305 1306 1307 1308 1309
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
1310
			nr_pages--;
L
Linus Torvalds 已提交
1311 1312 1313
			continue;
		}

N
Nick Piggin 已提交
1314 1315
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
H
Hugh Dickins 已提交
1316
		    !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1317 1318
			return i ? : -EFAULT;

H
Hugh Dickins 已提交
1319 1320
		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
H
Hugh Dickins 已提交
1321
					&start, &nr_pages, i, gup_flags);
H
Hugh Dickins 已提交
1322 1323
			continue;
		}
1324

L
Linus Torvalds 已提交
1325
		do {
1326
			struct page *page;
H
Hugh Dickins 已提交
1327
			unsigned int foll_flags = gup_flags;
L
Linus Torvalds 已提交
1328

1329
			/*
1330
			 * If we have a pending SIGKILL, don't keep faulting
H
Hugh Dickins 已提交
1331
			 * pages and potentially allocating memory.
1332
			 */
H
Hugh Dickins 已提交
1333
			if (unlikely(fatal_signal_pending(current)))
1334
				return i ? i : -ERESTARTSYS;
1335

1336
			cond_resched();
1337
			while (!(page = follow_page(vma, start, foll_flags))) {
1338
				int ret;
1339

1340 1341 1342 1343
				ret = handle_mm_fault(mm, vma, start,
					(foll_flags & FOLL_WRITE) ?
					FAULT_FLAG_WRITE : 0);

N
Nick Piggin 已提交
1344 1345 1346
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
1347 1348
					if (ret &
					    (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
N
Nick Piggin 已提交
1349 1350 1351 1352 1353 1354 1355 1356
						return i ? i : -EFAULT;
					BUG();
				}
				if (ret & VM_FAULT_MAJOR)
					tsk->maj_flt++;
				else
					tsk->min_flt++;

1357
				/*
N
Nick Piggin 已提交
1358 1359 1360 1361
				 * 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
1362 1363 1364 1365 1366 1367
				 * 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).
1368
				 */
1369 1370
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1371
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1372

1373
				cond_resched();
L
Linus Torvalds 已提交
1374
			}
1375 1376
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1377
			if (pages) {
1378
				pages[i] = page;
1379

1380
				flush_anon_page(vma, page, start);
1381
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1382 1383 1384 1385 1386
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
1387 1388 1389
			nr_pages--;
		} while (nr_pages && start < vma->vm_end);
	} while (nr_pages);
L
Linus Torvalds 已提交
1390 1391
	return i;
}
N
Nick Piggin 已提交
1392

1393 1394 1395 1396 1397
/**
 * get_user_pages() - pin user pages in memory
 * @tsk:	task_struct of target task
 * @mm:		mm_struct of target mm
 * @start:	starting user address
1398
 * @nr_pages:	number of pages from start to pin
1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409
 * @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
1410
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442
 * 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
1443
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1444
		unsigned long start, int nr_pages, int write, int force,
N
Nick Piggin 已提交
1445 1446
		struct page **pages, struct vm_area_struct **vmas)
{
H
Hugh Dickins 已提交
1447
	int flags = FOLL_TOUCH;
N
Nick Piggin 已提交
1448

H
Hugh Dickins 已提交
1449 1450
	if (pages)
		flags |= FOLL_GET;
N
Nick Piggin 已提交
1451
	if (write)
H
Hugh Dickins 已提交
1452
		flags |= FOLL_WRITE;
N
Nick Piggin 已提交
1453
	if (force)
H
Hugh Dickins 已提交
1454
		flags |= FOLL_FORCE;
N
Nick Piggin 已提交
1455

1456
	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
N
Nick Piggin 已提交
1457
}
L
Linus Torvalds 已提交
1458 1459
EXPORT_SYMBOL(get_user_pages);

H
Hugh Dickins 已提交
1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480
/**
 * 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
1481
			FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1)
H
Hugh Dickins 已提交
1482 1483 1484 1485 1486 1487
		return NULL;
	flush_cache_page(vma, addr, page_to_pfn(page));
	return page;
}
#endif /* CONFIG_ELF_CORE */

H
Harvey Harrison 已提交
1488 1489
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1490 1491 1492 1493
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1494
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1495 1496 1497 1498 1499 1500
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1501 1502 1503 1504 1505 1506 1507
/*
 * 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
1508 1509
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1510
{
N
Nick Piggin 已提交
1511
	struct mm_struct *mm = vma->vm_mm;
1512
	int retval;
1513
	pte_t *pte;
1514 1515
	spinlock_t *ptl;

1516
	retval = -EINVAL;
1517
	if (PageAnon(page))
1518
		goto out;
1519 1520
	retval = -ENOMEM;
	flush_dcache_page(page);
1521
	pte = get_locked_pte(mm, addr, &ptl);
1522
	if (!pte)
1523
		goto out;
1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
	inc_mm_counter(mm, file_rss);
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1535 1536
	pte_unmap_unlock(pte, ptl);
	return retval;
1537 1538 1539 1540 1541 1542
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1543 1544 1545 1546 1547 1548
/**
 * 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
 *
1549 1550 1551 1552 1553 1554
 * 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
1555
 * (see split_page()).
1556 1557 1558 1559 1560 1561 1562 1563 1564
 *
 * 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
1565 1566
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1567 1568 1569 1570 1571
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1572
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1573
	return insert_page(vma, addr, page, vma->vm_page_prot);
1574
}
1575
EXPORT_SYMBOL(vm_insert_page);
1576

N
Nick Piggin 已提交
1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595
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);
1596
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1597 1598 1599 1600 1601 1602 1603 1604

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

N
Nick Piggin 已提交
1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615
/**
 * 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
1616 1617 1618 1619 1620
 *
 * 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
1621 1622
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1623
			unsigned long pfn)
N
Nick Piggin 已提交
1624
{
1625
	int ret;
1626
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1627 1628 1629 1630 1631 1632
	/*
	 * 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
1633 1634 1635 1636 1637
	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
1638

N
Nick Piggin 已提交
1639 1640
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1641
	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1642 1643
		return -EINVAL;

1644
	ret = insert_pfn(vma, addr, pfn, pgprot);
1645 1646 1647 1648 1649

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

	return ret;
N
Nick Piggin 已提交
1650 1651
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1652

N
Nick Piggin 已提交
1653 1654 1655 1656
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
1657

N
Nick Piggin 已提交
1658 1659
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1660

N
Nick Piggin 已提交
1661 1662 1663 1664
	/*
	 * 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
1665 1666
	 * 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
1667 1668 1669 1670 1671 1672 1673 1674
	 */
	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
1675
}
N
Nick Piggin 已提交
1676
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1677

L
Linus Torvalds 已提交
1678 1679 1680 1681 1682 1683 1684 1685 1686 1687
/*
 * 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
1688
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1689

H
Hugh Dickins 已提交
1690
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1691 1692
	if (!pte)
		return -ENOMEM;
1693
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1694 1695
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1696
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1697 1698
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1699
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1700
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743
	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;
}

1744 1745 1746 1747 1748 1749 1750 1751 1752 1753
/**
 * 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
1754 1755 1756 1757 1758
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;
1759
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1760 1761 1762 1763 1764 1765 1766 1767
	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
1768 1769 1770 1771 1772
	 *   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.
1773 1774 1775
	 *   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
1776 1777 1778 1779
	 *
	 * 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
1780
	 */
1781
	if (addr == vma->vm_start && end == vma->vm_end) {
L
Linus Torvalds 已提交
1782
		vma->vm_pgoff = pfn;
1783
		vma->vm_flags |= VM_PFN_AT_MMAP;
1784
	} else if (is_cow_mapping(vma->vm_flags))
1785
		return -EINVAL;
L
Linus Torvalds 已提交
1786

1787
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1788

1789
	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1790 1791 1792 1793 1794 1795
	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);
1796
		vma->vm_flags &= ~VM_PFN_AT_MMAP;
1797
		return -EINVAL;
1798
	}
1799

L
Linus Torvalds 已提交
1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810
	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);
1811 1812 1813 1814

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

L
Linus Torvalds 已提交
1815 1816 1817 1818
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1819 1820 1821 1822 1823 1824
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;
1825
	pgtable_t token;
1826
	spinlock_t *uninitialized_var(ptl);
1827 1828 1829 1830 1831 1832 1833 1834 1835

	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));

1836 1837
	arch_enter_lazy_mmu_mode();

1838
	token = pmd_pgtable(*pmd);
1839 1840

	do {
1841
		err = fn(pte++, token, addr, data);
1842 1843
		if (err)
			break;
1844
	} while (addr += PAGE_SIZE, addr != end);
1845

1846 1847
	arch_leave_lazy_mmu_mode();

1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860
	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
1861 1862
	BUG_ON(pud_huge(*pud));

1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903
	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;
A
Andrea Arcangeli 已提交
1904
	unsigned long start = addr, end = addr + size;
1905 1906 1907
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1908
	mmu_notifier_invalidate_range_start(mm, start, end);
1909 1910 1911 1912 1913 1914 1915
	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);
A
Andrea Arcangeli 已提交
1916
	mmu_notifier_invalidate_range_end(mm, start, end);
1917 1918 1919 1920
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1921 1922 1923 1924 1925 1926 1927 1928 1929
/*
 * 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
1930
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1931 1932 1933 1934 1935
				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
1936 1937
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1938
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1939
		spin_unlock(ptl);
1940 1941 1942 1943 1944 1945
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958
/*
 * 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;
}

1959
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1960 1961 1962 1963 1964 1965 1966 1967 1968
{
	/*
	 * 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
1969 1970 1971 1972 1973 1974 1975 1976 1977
		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))
1978 1979
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1980
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1981 1982
	} else
		copy_user_highpage(dst, src, va, vma);
1983 1984
}

L
Linus Torvalds 已提交
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
/*
 * 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.
 *
1999 2000 2001
 * 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
2002
 */
2003 2004
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2005
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
2006
{
2007
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
2008
	pte_t entry;
N
Nick Piggin 已提交
2009
	int reuse = 0, ret = 0;
2010
	int page_mkwrite = 0;
2011
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
2012

2013
	old_page = vm_normal_page(vma, address, orig_pte);
2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024
	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;
2025
		goto gotten;
2026
	}
L
Linus Torvalds 已提交
2027

2028
	/*
P
Peter Zijlstra 已提交
2029 2030
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2031
	 */
H
Hugh Dickins 已提交
2032
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044
		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
2045
		}
2046
		reuse = reuse_swap_page(old_page);
2047
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2048
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2049
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
2050 2051 2052 2053 2054
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
2055
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2056 2057 2058 2059 2060 2061 2062 2063 2064
			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;

2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075
			/*
			 * 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);

2076 2077 2078 2079
			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
			if (unlikely(tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
				ret = tmp;
2080
				goto unwritable_page;
2081
			}
N
Nick Piggin 已提交
2082 2083 2084 2085 2086 2087 2088 2089 2090
			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));
2091 2092 2093 2094 2095 2096 2097 2098 2099

			/*
			 * 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
2100 2101 2102
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				page_cache_release(old_page);
2103
				goto unlock;
N
Nick Piggin 已提交
2104
			}
2105 2106

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2107
		}
2108 2109
		dirty_page = old_page;
		get_page(dirty_page);
2110 2111 2112 2113
		reuse = 1;
	}

	if (reuse) {
2114
reuse:
2115 2116 2117
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2118
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2119
			update_mmu_cache(vma, address, page_table);
2120 2121
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
2122 2123 2124 2125 2126
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2127
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2128
gotten:
2129
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2130 2131

	if (unlikely(anon_vma_prepare(vma)))
2132
		goto oom;
H
Hugh Dickins 已提交
2133

H
Hugh Dickins 已提交
2134
	if (is_zero_pfn(pte_pfn(orig_pte))) {
H
Hugh Dickins 已提交
2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145
		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
2146 2147 2148 2149
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
2150
	if ((vma->vm_flags & VM_LOCKED) && old_page) {
N
Nick Piggin 已提交
2151 2152 2153 2154
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
2155

K
KAMEZAWA Hiroyuki 已提交
2156
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2157 2158
		goto oom_free_new;

L
Linus Torvalds 已提交
2159 2160 2161
	/*
	 * Re-check the pte - we dropped the lock
	 */
2162
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2163
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2164 2165 2166 2167 2168 2169
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
2170
			inc_mm_counter(mm, anon_rss);
2171
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2172 2173
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2174 2175 2176 2177 2178 2179
		/*
		 * 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.
		 */
2180
		ptep_clear_flush(vma, address, page_table);
N
Nick Piggin 已提交
2181
		page_add_new_anon_rmap(new_page, vma, address);
2182 2183 2184 2185 2186 2187
		/*
		 * 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);
2188
		update_mmu_cache(vma, address, page_table);
N
Nick Piggin 已提交
2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211
		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.
			 */
2212
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2213 2214
		}

L
Linus Torvalds 已提交
2215 2216
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2217
		ret |= VM_FAULT_WRITE;
2218 2219 2220
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2221 2222 2223 2224
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
2225
unlock:
2226
	pte_unmap_unlock(page_table, ptl);
2227
	if (dirty_page) {
2228 2229 2230 2231 2232 2233 2234 2235
		/*
		 * 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
2236 2237 2238 2239
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
			set_page_dirty_balance(dirty_page, page_mkwrite);
		}
2240
		put_page(dirty_page);
N
Nick Piggin 已提交
2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258
		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);
2259
	}
N
Nick Piggin 已提交
2260
	return ret;
2261
oom_free_new:
2262
	page_cache_release(new_page);
2263
oom:
N
Nick Piggin 已提交
2264 2265 2266 2267 2268
	if (old_page) {
		if (page_mkwrite) {
			unlock_page(old_page);
			page_cache_release(old_page);
		}
H
Hugh Dickins 已提交
2269
		page_cache_release(old_page);
N
Nick Piggin 已提交
2270
	}
L
Linus Torvalds 已提交
2271
	return VM_FAULT_OOM;
2272 2273 2274

unwritable_page:
	page_cache_release(old_page);
2275
	return ret;
L
Linus Torvalds 已提交
2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302
}

/*
 * 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
2303
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329
 * 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;

2330 2331
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2332
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2333 2334
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2335 2336
	 */

L
Linus Torvalds 已提交
2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347
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;
		}
	}

2348 2349
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2350
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2351

2352
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2353 2354 2355 2356 2357 2358
		/* 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 */
2359
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 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 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425
		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;
	}
}

/**
2426
 * 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
2427
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2428 2429
 * @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
2430
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463
 * 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);

2464
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480
	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);

2481 2482 2483 2484 2485 2486 2487 2488 2489
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
2490
	if (!inode->i_op->truncate_range)
2491 2492
		return -ENOSYS;

2493
	mutex_lock(&inode->i_mutex);
2494 2495 2496
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2497
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2498 2499
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2500
	mutex_unlock(&inode->i_mutex);
2501 2502 2503 2504

	return 0;
}

L
Linus Torvalds 已提交
2505
/*
2506 2507 2508
 * 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
2509
 */
2510 2511
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2512
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2513
{
2514
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2515
	struct page *page;
2516
	swp_entry_t entry;
L
Linus Torvalds 已提交
2517
	pte_t pte;
2518
	struct mem_cgroup *ptr = NULL;
N
Nick Piggin 已提交
2519
	int ret = 0;
L
Linus Torvalds 已提交
2520

H
Hugh Dickins 已提交
2521
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2522
		goto out;
2523 2524

	entry = pte_to_swp_entry(orig_pte);
2525 2526 2527 2528 2529 2530 2531
	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
2532
			ret = VM_FAULT_SIGBUS;
2533
		}
2534 2535
		goto out;
	}
2536
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2537 2538
	page = lookup_swap_cache(entry);
	if (!page) {
H
Hugh Dickins 已提交
2539
		grab_swap_token(mm); /* Contend for token _before_ read-in */
2540 2541
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2542 2543
		if (!page) {
			/*
2544 2545
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2546
			 */
2547
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2548 2549
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2550
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2551
			goto unlock;
L
Linus Torvalds 已提交
2552 2553 2554 2555
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2556
		count_vm_event(PGMAJFAULT);
2557
	} else if (PageHWPoison(page)) {
2558 2559 2560 2561
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2562 2563
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2564
		goto out_release;
L
Linus Torvalds 已提交
2565 2566
	}

2567 2568 2569
	lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

H
Hugh Dickins 已提交
2570 2571 2572 2573 2574 2575
	page = ksm_might_need_to_copy(page, vma, address);
	if (!page) {
		ret = VM_FAULT_OOM;
		goto out;
	}

K
KAMEZAWA Hiroyuki 已提交
2576
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2577
		ret = VM_FAULT_OOM;
2578
		goto out_page;
2579 2580
	}

L
Linus Torvalds 已提交
2581
	/*
2582
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2583
	 */
2584
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2585
	if (unlikely(!pte_same(*page_table, orig_pte)))
2586 2587 2588 2589 2590
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2591 2592
	}

2593 2594 2595 2596 2597 2598 2599 2600
	/*
	 * 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.
2601 2602 2603 2604
	 * 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().
2605
	 */
L
Linus Torvalds 已提交
2606

2607
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2608
	pte = mk_pte(page, vma->vm_page_prot);
2609
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2610
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2611
		flags &= ~FAULT_FLAG_WRITE;
L
Linus Torvalds 已提交
2612 2613 2614 2615
	}
	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
	page_add_anon_rmap(page, vma, address);
2616 2617
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
2618

2619
	swap_free(entry);
N
Nick Piggin 已提交
2620
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2621
		try_to_free_swap(page);
2622 2623
	unlock_page(page);

2624
	if (flags & FAULT_FLAG_WRITE) {
2625 2626 2627
		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
2628 2629 2630 2631
		goto out;
	}

	/* No need to invalidate - it was non-present before */
2632
	update_mmu_cache(vma, address, page_table);
2633
unlock:
2634
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2635 2636
out:
	return ret;
2637
out_nomap:
2638
	mem_cgroup_cancel_charge_swapin(ptr);
2639
	pte_unmap_unlock(page_table, ptl);
2640
out_page:
2641
	unlock_page(page);
2642
out_release:
2643
	page_cache_release(page);
2644
	return ret;
L
Linus Torvalds 已提交
2645 2646 2647
}

/*
2648 2649 2650
 * 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
2651
 */
2652 2653
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2654
		unsigned int flags)
L
Linus Torvalds 已提交
2655
{
2656 2657
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2658 2659
	pte_t entry;

H
Hugh Dickins 已提交
2660 2661 2662
	if (!(flags & FAULT_FLAG_WRITE)) {
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
H
Hugh Dickins 已提交
2663 2664 2665 2666 2667 2668 2669
		ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
		if (!pte_none(*page_table))
			goto unlock;
		goto setpte;
	}

N
Nick Piggin 已提交
2670 2671
	/* Allocate our own private page. */
	pte_unmap(page_table);
2672

N
Nick Piggin 已提交
2673 2674 2675 2676 2677
	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
2678
	__SetPageUptodate(page);
2679

K
KAMEZAWA Hiroyuki 已提交
2680
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2681 2682
		goto oom_free_page;

N
Nick Piggin 已提交
2683
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
2684 2685
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
2686

N
Nick Piggin 已提交
2687
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2688
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
2689
		goto release;
H
Hugh Dickins 已提交
2690

N
Nick Piggin 已提交
2691 2692
	inc_mm_counter(mm, anon_rss);
	page_add_new_anon_rmap(page, vma, address);
H
Hugh Dickins 已提交
2693
setpte:
2694
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2695 2696

	/* No need to invalidate - it was non-present before */
2697
	update_mmu_cache(vma, address, page_table);
2698
unlock:
2699
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2700
	return 0;
2701
release:
2702
	mem_cgroup_uncharge_page(page);
2703 2704
	page_cache_release(page);
	goto unlock;
2705
oom_free_page:
2706
	page_cache_release(page);
2707
oom:
L
Linus Torvalds 已提交
2708 2709 2710 2711
	return VM_FAULT_OOM;
}

/*
2712
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2713
 * tries to share with existing pages, but makes a separate copy if
2714 2715
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2716 2717 2718 2719
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2720
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2721
 * but allow concurrent faults), and pte neither mapped nor locked.
2722
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2723
 */
2724
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2725
		unsigned long address, pmd_t *pmd,
2726
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2727
{
2728
	pte_t *page_table;
2729
	spinlock_t *ptl;
N
Nick Piggin 已提交
2730
	struct page *page;
L
Linus Torvalds 已提交
2731 2732
	pte_t entry;
	int anon = 0;
2733
	int charged = 0;
2734
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2735 2736
	struct vm_fault vmf;
	int ret;
2737
	int page_mkwrite = 0;
2738

N
Nick Piggin 已提交
2739 2740 2741 2742
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2743

N
Nick Piggin 已提交
2744 2745 2746
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2747

2748 2749 2750 2751 2752 2753
	if (unlikely(PageHWPoison(vmf.page))) {
		if (ret & VM_FAULT_LOCKED)
			unlock_page(vmf.page);
		return VM_FAULT_HWPOISON;
	}

2754
	/*
N
Nick Piggin 已提交
2755
	 * For consistency in subsequent calls, make the faulted page always
2756 2757
	 * locked.
	 */
N
Nick Piggin 已提交
2758
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2759
		lock_page(vmf.page);
2760
	else
N
Nick Piggin 已提交
2761
		VM_BUG_ON(!PageLocked(vmf.page));
2762

L
Linus Torvalds 已提交
2763 2764 2765
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2766
	page = vmf.page;
2767
	if (flags & FAULT_FLAG_WRITE) {
2768
		if (!(vma->vm_flags & VM_SHARED)) {
2769
			anon = 1;
2770
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2771
				ret = VM_FAULT_OOM;
2772
				goto out;
2773
			}
N
Nick Piggin 已提交
2774 2775
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2776
			if (!page) {
N
Nick Piggin 已提交
2777
				ret = VM_FAULT_OOM;
2778
				goto out;
2779
			}
K
KAMEZAWA Hiroyuki 已提交
2780
			if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2781 2782 2783 2784 2785
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
2786 2787 2788 2789 2790 2791
			/*
			 * 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
2792
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2793
			__SetPageUptodate(page);
2794
		} else {
2795 2796
			/*
			 * If the page will be shareable, see if the backing
2797
			 * address space wants to know that the page is about
2798 2799
			 * to become writable
			 */
2800
			if (vma->vm_ops->page_mkwrite) {
2801 2802
				int tmp;

2803
				unlock_page(page);
N
Nick Piggin 已提交
2804
				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2805 2806 2807 2808
				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
2809
					goto unwritable_page;
N
Nick Piggin 已提交
2810
				}
N
Nick Piggin 已提交
2811 2812 2813 2814 2815 2816 2817 2818 2819
				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));
2820
				page_mkwrite = 1;
2821 2822
			}
		}
2823

L
Linus Torvalds 已提交
2824 2825
	}

2826
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2827 2828 2829 2830 2831 2832

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
2833
	 * Note that if FAULT_FLAG_WRITE is set, we either now have
L
Linus Torvalds 已提交
2834 2835 2836 2837 2838
	 * 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... */
2839
	if (likely(pte_same(*page_table, orig_pte))) {
2840 2841
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2842
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2843 2844
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
2845 2846
			inc_mm_counter(mm, anon_rss);
			page_add_new_anon_rmap(page, vma, address);
2847
		} else {
2848
			inc_mm_counter(mm, file_rss);
2849
			page_add_file_rmap(page);
2850
			if (flags & FAULT_FLAG_WRITE) {
2851
				dirty_page = page;
2852 2853
				get_page(dirty_page);
			}
2854
		}
2855
		set_pte_at(mm, address, page_table, entry);
2856 2857

		/* no need to invalidate: a not-present page won't be cached */
2858
		update_mmu_cache(vma, address, page_table);
L
Linus Torvalds 已提交
2859
	} else {
2860 2861
		if (charged)
			mem_cgroup_uncharge_page(page);
2862 2863 2864
		if (anon)
			page_cache_release(page);
		else
2865
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2866 2867
	}

2868
	pte_unmap_unlock(page_table, ptl);
2869 2870

out:
N
Nick Piggin 已提交
2871 2872
	if (dirty_page) {
		struct address_space *mapping = page->mapping;
2873

N
Nick Piggin 已提交
2874 2875 2876
		if (set_page_dirty(dirty_page))
			page_mkwrite = 1;
		unlock_page(dirty_page);
2877
		put_page(dirty_page);
N
Nick Piggin 已提交
2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892
		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);
2893
	}
2894

N
Nick Piggin 已提交
2895
	return ret;
N
Nick Piggin 已提交
2896 2897 2898 2899

unwritable_page:
	page_cache_release(page);
	return ret;
2900
}
2901

2902 2903
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2904
		unsigned int flags, pte_t orig_pte)
2905 2906
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2907
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2908

2909 2910
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2911 2912
}

L
Linus Torvalds 已提交
2913 2914 2915 2916
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2917 2918 2919 2920
 *
 * 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
2921
 */
N
Nick Piggin 已提交
2922
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2923
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2924
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2925
{
2926
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2927

2928 2929
	flags |= FAULT_FLAG_NONLINEAR;

H
Hugh Dickins 已提交
2930
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2931
		return 0;
L
Linus Torvalds 已提交
2932

2933
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2934 2935 2936
		/*
		 * Page table corrupted: show pte and kill process.
		 */
2937
		print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
2938
		return VM_FAULT_SIGBUS;
2939 2940 2941
	}

	pgoff = pte_to_pgoff(orig_pte);
2942
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953
}

/*
 * 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
2954 2955 2956
 * 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
2957 2958
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2959
		struct vm_area_struct *vma, unsigned long address,
2960
		pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
2961 2962
{
	pte_t entry;
2963
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2964

2965
	entry = *pte;
L
Linus Torvalds 已提交
2966
	if (!pte_present(entry)) {
2967
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2968
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2969
				if (likely(vma->vm_ops->fault))
2970
					return do_linear_fault(mm, vma, address,
2971
						pte, pmd, flags, entry);
J
Jes Sorensen 已提交
2972 2973
			}
			return do_anonymous_page(mm, vma, address,
2974
						 pte, pmd, flags);
2975
		}
L
Linus Torvalds 已提交
2976
		if (pte_file(entry))
N
Nick Piggin 已提交
2977
			return do_nonlinear_fault(mm, vma, address,
2978
					pte, pmd, flags, entry);
2979
		return do_swap_page(mm, vma, address,
2980
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
2981 2982
	}

H
Hugh Dickins 已提交
2983
	ptl = pte_lockptr(mm, pmd);
2984 2985 2986
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
2987
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
2988
		if (!pte_write(entry))
2989 2990
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2991 2992 2993
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2994
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
2995
		update_mmu_cache(vma, address, pte);
2996 2997 2998 2999 3000 3001 3002
	} 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.
		 */
3003
		if (flags & FAULT_FLAG_WRITE)
3004 3005
			flush_tlb_page(vma, address);
	}
3006 3007
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3008
	return 0;
L
Linus Torvalds 已提交
3009 3010 3011 3012 3013
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
3014
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3015
		unsigned long address, unsigned int flags)
L
Linus Torvalds 已提交
3016 3017 3018 3019 3020 3021 3022 3023
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

3024
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
3025

3026
	if (unlikely(is_vm_hugetlb_page(vma)))
3027
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3028 3029 3030 3031

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3032
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3033 3034
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3035
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3036 3037
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
3038
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3039

3040
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3041 3042 3043 3044 3045
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3046
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3047
 */
3048
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3049
{
H
Hugh Dickins 已提交
3050 3051
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3052
		return -ENOMEM;
L
Linus Torvalds 已提交
3053

3054 3055
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3056
	spin_lock(&mm->page_table_lock);
3057
	if (pgd_present(*pgd))		/* Another has populated it */
3058
		pud_free(mm, new);
3059 3060
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3061
	spin_unlock(&mm->page_table_lock);
3062
	return 0;
L
Linus Torvalds 已提交
3063 3064 3065 3066 3067 3068
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3069
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3070
 */
3071
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3072
{
H
Hugh Dickins 已提交
3073 3074
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3075
		return -ENOMEM;
L
Linus Torvalds 已提交
3076

3077 3078
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3079
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3080
#ifndef __ARCH_HAS_4LEVEL_HACK
3081
	if (pud_present(*pud))		/* Another has populated it */
3082
		pmd_free(mm, new);
3083 3084
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3085
#else
3086
	if (pgd_present(*pud))		/* Another has populated it */
3087
		pmd_free(mm, new);
3088 3089
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3090
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3091
	spin_unlock(&mm->page_table_lock);
3092
	return 0;
3093
}
L
Linus Torvalds 已提交
3094 3095 3096 3097 3098 3099 3100 3101 3102
#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
3103
		return -ENOMEM;
L
Linus Torvalds 已提交
3104
	write = (vma->vm_flags & VM_WRITE) != 0;
3105 3106
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
3107
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
3108 3109
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
3110
	if (ret < 0)
L
Linus Torvalds 已提交
3111
		return ret;
3112
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
3113 3114 3115 3116 3117
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
3118
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
3119 3120 3121 3122 3123 3124

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
3125 3126
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
3127 3128 3129 3130 3131 3132 3133
	/*
	 * 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
3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157
	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 */
3158

J
Johannes Weiner 已提交
3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195
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
3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224
/**
 * 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);

3225
#ifdef CONFIG_HAVE_IOREMAP_PROT
3226 3227 3228
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3229
{
3230
	int ret = -EINVAL;
3231 3232 3233
	pte_t *ptep, pte;
	spinlock_t *ptl;

3234 3235
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3236

3237
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3238
		goto out;
3239
	pte = *ptep;
3240

3241 3242 3243 3244
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3245
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3246

3247
	ret = 0;
3248 3249 3250
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3251
	return ret;
3252 3253 3254 3255 3256 3257 3258
}

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
3259
	void __iomem *maddr;
3260 3261
	int offset = addr & (PAGE_SIZE-1);

3262
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275
		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

3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291
/*
 * 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
3292
	/* ignore errors, just check how much was successfully transferred */
3293 3294 3295
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3296
		struct page *page = NULL;
3297 3298 3299

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315
		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;
3316
		} else {
3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332
			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);
3333 3334 3335 3336 3337 3338 3339 3340 3341 3342
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
3343 3344 3345 3346 3347 3348 3349 3350 3351

/*
 * 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;

3352 3353 3354 3355 3356 3357 3358
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3359 3360 3361 3362 3363 3364 3365 3366
	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;

3367
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380
			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);
}
3381 3382 3383 3384

#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
3385 3386 3387 3388 3389 3390 3391 3392 3393
	/*
	 * 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;

3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404
	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