memory.c 91.3 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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/*
 * 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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		/*
		 * Hide vma from rmap and vmtruncate before freeing pgtables
		 */
		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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/*
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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;
		if (!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)))
			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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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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}

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/*
 * 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.
 */

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static inline void
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copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
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		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
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		unsigned long addr, int *rss)
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{
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	unsigned long vm_flags = vma->vm_flags;
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	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)) {
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			swp_entry_t entry = pte_to_swp_entry(pte);

			swap_duplicate(entry);
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			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
562 563 564
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
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				spin_unlock(&mmlist_lock);
			}
567 568 569 570 571 572 573 574 575 576
			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
577
		}
578
		goto out_set_pte;
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579 580 581 582 583 584
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
585
	if (is_cow_mapping(vm_flags)) {
L
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586
		ptep_set_wrprotect(src_mm, addr, src_pte);
587
		pte = pte_wrprotect(pte);
L
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588 589 590 591 592 593 594 595 596
	}

	/*
	 * 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);
597 598 599 600

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
H
Hugh Dickins 已提交
601
		page_dup_rmap(page);
602 603
		rss[!!PageAnon(page)]++;
	}
604 605 606

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
L
Linus Torvalds 已提交
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}

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)
{
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
614
	spinlock_t *src_ptl, *dst_ptl;
615
	int progress = 0;
H
Hugh Dickins 已提交
616
	int rss[2];
L
Linus Torvalds 已提交
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again:
619
	rss[1] = rss[0] = 0;
H
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620
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
621 622 623
	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
624
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
625
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
626
	arch_enter_lazy_mmu_mode();
L
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627 628 629 630 631 632

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
633 634 635
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
636
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
637 638
				break;
		}
L
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639 640 641 642
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
643
		copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
L
Linus Torvalds 已提交
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		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

647
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
648
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
649
	pte_unmap_nested(src_pte - 1);
650
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
651 652
	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
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Linus Torvalds 已提交
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	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
709
	int ret;
L
Linus Torvalds 已提交
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711 712 713 714 715 716
	/*
	 * 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.
	 */
717
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
718 719 720 721
		if (!vma->anon_vma)
			return 0;
	}

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

725
	if (unlikely(is_pfn_mapping(vma))) {
726 727 728 729 730 731 732 733 734
		/*
		 * 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
735 736 737 738 739 740 741 742 743 744
	/*
	 * 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
745 746 747 748 749 750
	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
751 752 753 754 755
		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
756
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
757 758 759 760 761

	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
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}

764
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
765
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
766
				unsigned long addr, unsigned long end,
767
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
768
{
N
Nick Piggin 已提交
769
	struct mm_struct *mm = tlb->mm;
L
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770
	pte_t *pte;
771
	spinlock_t *ptl;
772 773
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
774

775
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
776
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
777 778
	do {
		pte_t ptent = *pte;
779 780
		if (pte_none(ptent)) {
			(*zap_work)--;
L
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781
			continue;
782
		}
783 784 785

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
786
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
787
			struct page *page;
788

789
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
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			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
808
			ptent = ptep_get_and_clear_full(mm, addr, pte,
809
							tlb->fullmm);
L
Linus Torvalds 已提交
810 811 812 813 814 815
			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
816
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
817 818
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
819
				anon_rss--;
820 821 822
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
823 824
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
825
					mark_page_accessed(page);
H
Hugh Dickins 已提交
826
				file_rss--;
827
			}
828
			page_remove_rmap(page);
829 830
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
L
Linus Torvalds 已提交
831 832 833 834 835 836 837 838 839
			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;
840 841 842 843 844 845
		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);
846
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
847
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
848

H
Hugh Dickins 已提交
849
	add_mm_rss(mm, file_rss, anon_rss);
850
	arch_leave_lazy_mmu_mode();
851
	pte_unmap_unlock(pte - 1, ptl);
852 853

	return addr;
L
Linus Torvalds 已提交
854 855
}

856
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
857
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
858
				unsigned long addr, unsigned long end,
859
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
860 861 862 863 864 865 866
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
867 868
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
869
			continue;
870 871 872 873 874 875
		}
		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
876 877
}

878
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
879
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
880
				unsigned long addr, unsigned long end,
881
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
882 883 884 885 886 887 888
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
889 890
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
891
			continue;
892 893 894 895 896 897
		}
		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
898 899
}

900 901
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
902
				unsigned long addr, unsigned long end,
903
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
904 905 906 907 908 909 910 911 912 913 914 915
{
	pgd_t *pgd;
	unsigned long next;

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

	BUG_ON(addr >= end);
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
916 917
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
918
			continue;
919 920 921 922
		}
		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
923
	tlb_end_vma(tlb, vma);
924 925

	return addr;
L
Linus Torvalds 已提交
926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943
}

#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
 *
944
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
945
 *
946
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
947
 *
948 949
 * 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
950 951 952 953 954 955 956 957 958 959 960
 * 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.
 */
961
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
962 963 964 965
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
966
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
967 968
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
969
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
970
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
971
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
972
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
973

A
Andrea Arcangeli 已提交
974
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
975 976 977 978 979 980 981 982 983 984 985 986 987
	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;

988
		if (unlikely(is_pfn_mapping(vma)))
989 990
			untrack_pfn_vma(vma, 0, 0);

L
Linus Torvalds 已提交
991 992 993 994 995 996
		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

997
			if (unlikely(is_vm_hugetlb_page(vma))) {
998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011
				/*
				 * 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) /
1012
					pages_per_huge_page(hstate_vma(vma));
1013 1014
				}

1015 1016 1017 1018 1019 1020 1021 1022
				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
1023 1024 1025 1026 1027
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
1028
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
1029
				if (i_mmap_lock) {
1030
					*tlbp = NULL;
L
Linus Torvalds 已提交
1031 1032 1033 1034 1035
					goto out;
				}
				cond_resched();
			}

1036
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
1037
			tlb_start_valid = 0;
1038
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1039 1040 1041
		}
	}
out:
A
Andrea Arcangeli 已提交
1042
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1043
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
1044 1045 1046 1047 1048 1049 1050 1051 1052
}

/**
 * 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
 */
1053
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1054 1055 1056 1057 1058 1059 1060 1061 1062
		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);
1063
	update_hiwater_rss(mm);
1064 1065 1066
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
1067
	return end;
L
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1068 1069
}

1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092
/**
 * 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
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1093 1094 1095
/*
 * Do a quick page-table lookup for a single page.
 */
1096
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1097
			unsigned int flags)
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1098 1099 1100 1101 1102
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1103
	spinlock_t *ptl;
L
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1104
	struct page *page;
1105
	struct mm_struct *mm = vma->vm_mm;
L
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1106

1107 1108 1109 1110 1111
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
L
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1112

1113
	page = NULL;
L
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1114 1115
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1116
		goto no_page_table;
L
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1117 1118

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1119
	if (pud_none(*pud))
1120
		goto no_page_table;
A
Andi Kleen 已提交
1121 1122 1123 1124 1125 1126 1127 1128
	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
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1129
	pmd = pmd_offset(pud, address);
1130
	if (pmd_none(*pmd))
1131 1132 1133 1134
		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
1135
		goto out;
1136
	}
1137 1138 1139
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1140
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1141 1142

	pte = *ptep;
1143
	if (!pte_present(pte))
1144
		goto no_page;
1145 1146
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
1147 1148
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
1149
		goto bad_page;
L
Linus Torvalds 已提交
1150

1151 1152 1153 1154 1155 1156
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
1157 1158 1159 1160 1161
		/*
		 * 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().
		 */
1162 1163 1164 1165
		mark_page_accessed(page);
	}
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1166
out:
1167
	return page;
L
Linus Torvalds 已提交
1168

1169 1170 1171 1172 1173 1174 1175 1176 1177
bad_page:
	pte_unmap_unlock(ptep, ptl);
	return ERR_PTR(-EFAULT);

no_page:
	pte_unmap_unlock(ptep, ptl);
	if (!pte_none(pte))
		return page;
	/* Fall through to ZERO_PAGE handling */
1178 1179 1180 1181 1182 1183
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
	 * has touched so far, we don't want to allocate page tables.
	 */
	if (flags & FOLL_ANON) {
N
Nick Piggin 已提交
1184
		page = ZERO_PAGE(0);
1185 1186 1187 1188 1189
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
1190 1191
}

1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204
/* Can we do the FOLL_ANON optimization? */
static inline int use_zero_page(struct vm_area_struct *vma)
{
	/*
	 * We don't want to optimize FOLL_ANON for make_pages_present()
	 * when it tries to page in a VM_LOCKED region. As to VM_SHARED,
	 * we want to get the page from the page tables to make sure
	 * that we serialize and update with any other user of that
	 * mapping.
	 */
	if (vma->vm_flags & (VM_LOCKED | VM_SHARED))
		return 0;
	/*
N
Nick Piggin 已提交
1205
	 * And if we have a fault routine, it's not an anonymous region.
1206
	 */
N
Nick Piggin 已提交
1207
	return !vma->vm_ops || !vma->vm_ops->fault;
1208 1209
}

N
Nick Piggin 已提交
1210 1211 1212


int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1213 1214
		     unsigned long start, int nr_pages, int flags,
		     struct page **pages, struct vm_area_struct **vmas)
L
Linus Torvalds 已提交
1215 1216
{
	int i;
N
Nick Piggin 已提交
1217 1218 1219 1220
	unsigned int vm_flags = 0;
	int write = !!(flags & GUP_FLAGS_WRITE);
	int force = !!(flags & GUP_FLAGS_FORCE);
	int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
1221
	int ignore_sigkill = !!(flags & GUP_FLAGS_IGNORE_SIGKILL);
L
Linus Torvalds 已提交
1222

1223
	if (nr_pages <= 0)
1224
		return 0;
L
Linus Torvalds 已提交
1225 1226 1227 1228
	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
1229 1230
	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
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1231 1232 1233
	i = 0;

	do {
1234 1235
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
1236 1237 1238 1239 1240 1241 1242 1243 1244

		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
1245 1246 1247

			/* user gate pages are read-only */
			if (!ignore && write)
L
Linus Torvalds 已提交
1248 1249 1250 1251 1252 1253 1254 1255 1256
				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);
1257 1258
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1259
			pte = pte_offset_map(pmd, pg);
1260 1261 1262 1263
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1264
			if (pages) {
1265
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1266 1267 1268
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1269 1270 1271 1272 1273 1274
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
1275
			nr_pages--;
L
Linus Torvalds 已提交
1276 1277 1278
			continue;
		}

N
Nick Piggin 已提交
1279 1280 1281
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
		    (!ignore && !(vm_flags & vma->vm_flags)))
L
Linus Torvalds 已提交
1282 1283 1284 1285
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
1286
						&start, &nr_pages, i, write);
L
Linus Torvalds 已提交
1287 1288
			continue;
		}
1289 1290 1291 1292

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
1293
		if (!write && use_zero_page(vma))
1294 1295
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1296
		do {
1297
			struct page *page;
L
Linus Torvalds 已提交
1298

1299
			/*
1300 1301 1302 1303 1304
			 * If we have a pending SIGKILL, don't keep faulting
			 * pages and potentially allocating memory, unless
			 * current is handling munlock--e.g., on exit. In
			 * that case, we are not allocating memory.  Rather,
			 * we're only unlocking already resident/mapped pages.
1305
			 */
1306 1307 1308
			if (unlikely(!ignore_sigkill &&
					fatal_signal_pending(current)))
				return i ? i : -ERESTARTSYS;
1309

1310 1311
			if (write)
				foll_flags |= FOLL_WRITE;
1312

1313
			cond_resched();
1314
			while (!(page = follow_page(vma, start, foll_flags))) {
1315
				int ret;
1316

1317 1318 1319 1320
				ret = handle_mm_fault(mm, vma, start,
					(foll_flags & FOLL_WRITE) ?
					FAULT_FLAG_WRITE : 0);

N
Nick Piggin 已提交
1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
					else if (ret & VM_FAULT_SIGBUS)
						return i ? i : -EFAULT;
					BUG();
				}
				if (ret & VM_FAULT_MAJOR)
					tsk->maj_flt++;
				else
					tsk->min_flt++;

1333
				/*
N
Nick Piggin 已提交
1334 1335 1336 1337
				 * 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
1338 1339 1340 1341 1342 1343
				 * 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).
1344
				 */
1345 1346
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1347
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1348

1349
				cond_resched();
L
Linus Torvalds 已提交
1350
			}
1351 1352
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1353
			if (pages) {
1354
				pages[i] = page;
1355

1356
				flush_anon_page(vma, page, start);
1357
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1358 1359 1360 1361 1362
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
1363 1364 1365
			nr_pages--;
		} while (nr_pages && start < vma->vm_end);
	} while (nr_pages);
L
Linus Torvalds 已提交
1366 1367
	return i;
}
N
Nick Piggin 已提交
1368

1369 1370 1371 1372 1373
/**
 * get_user_pages() - pin user pages in memory
 * @tsk:	task_struct of target task
 * @mm:		mm_struct of target mm
 * @start:	starting user address
1374
 * @nr_pages:	number of pages from start to pin
1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385
 * @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
1386
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418
 * 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
1419
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1420
		unsigned long start, int nr_pages, int write, int force,
N
Nick Piggin 已提交
1421 1422 1423 1424 1425 1426 1427 1428 1429
		struct page **pages, struct vm_area_struct **vmas)
{
	int flags = 0;

	if (write)
		flags |= GUP_FLAGS_WRITE;
	if (force)
		flags |= GUP_FLAGS_FORCE;

1430
	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
N
Nick Piggin 已提交
1431 1432
}

L
Linus Torvalds 已提交
1433 1434
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1435 1436
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1437 1438 1439 1440
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1441
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1442 1443 1444 1445 1446 1447
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1448 1449 1450 1451 1452 1453 1454
/*
 * 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
1455 1456
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1457
{
N
Nick Piggin 已提交
1458
	struct mm_struct *mm = vma->vm_mm;
1459
	int retval;
1460
	pte_t *pte;
1461 1462
	spinlock_t *ptl;

1463
	retval = -EINVAL;
1464
	if (PageAnon(page))
1465
		goto out;
1466 1467
	retval = -ENOMEM;
	flush_dcache_page(page);
1468
	pte = get_locked_pte(mm, addr, &ptl);
1469
	if (!pte)
1470
		goto out;
1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481
	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;
1482 1483
	pte_unmap_unlock(pte, ptl);
	return retval;
1484 1485 1486 1487 1488 1489
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1490 1491 1492 1493 1494 1495
/**
 * 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
 *
1496 1497 1498 1499 1500 1501
 * 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
1502
 * (see split_page()).
1503 1504 1505 1506 1507 1508 1509 1510 1511
 *
 * 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
1512 1513
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1514 1515 1516 1517 1518
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1519
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1520
	return insert_page(vma, addr, page, vma->vm_page_prot);
1521
}
1522
EXPORT_SYMBOL(vm_insert_page);
1523

N
Nick Piggin 已提交
1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551
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);
	update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */

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

N
Nick Piggin 已提交
1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562
/**
 * 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
1563 1564 1565 1566 1567
 *
 * 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
1568 1569
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1570
			unsigned long pfn)
N
Nick Piggin 已提交
1571
{
1572
	int ret;
1573
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1574 1575 1576 1577 1578 1579
	/*
	 * 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
1580 1581 1582 1583 1584
	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
1585

N
Nick Piggin 已提交
1586 1587
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1588
	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1589 1590
		return -EINVAL;

1591
	ret = insert_pfn(vma, addr, pfn, pgprot);
1592 1593 1594 1595 1596

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

	return ret;
N
Nick Piggin 已提交
1597 1598
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1599

N
Nick Piggin 已提交
1600 1601 1602 1603
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
1604

N
Nick Piggin 已提交
1605 1606
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1607

N
Nick Piggin 已提交
1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620
	/*
	 * 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
	 * than insert_pfn).
	 */
	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
1621
}
N
Nick Piggin 已提交
1622
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1623

L
Linus Torvalds 已提交
1624 1625 1626 1627 1628 1629 1630 1631 1632 1633
/*
 * 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
1634
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1635

H
Hugh Dickins 已提交
1636
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1637 1638
	if (!pte)
		return -ENOMEM;
1639
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1640 1641
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1642
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1643 1644
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1645
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1646
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689
	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;
}

1690 1691 1692 1693 1694 1695 1696 1697 1698 1699
/**
 * 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
1700 1701 1702 1703 1704
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;
1705
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1706 1707 1708 1709 1710 1711 1712 1713
	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
1714 1715 1716 1717 1718
	 *   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.
1719 1720 1721
	 *   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
1722 1723 1724 1725
	 *
	 * 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
1726
	 */
1727
	if (addr == vma->vm_start && end == vma->vm_end) {
L
Linus Torvalds 已提交
1728
		vma->vm_pgoff = pfn;
1729
		vma->vm_flags |= VM_PFN_AT_MMAP;
1730
	} else if (is_cow_mapping(vma->vm_flags))
1731
		return -EINVAL;
L
Linus Torvalds 已提交
1732

1733
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1734

1735
	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1736 1737 1738 1739 1740 1741
	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);
1742
		vma->vm_flags &= ~VM_PFN_AT_MMAP;
1743
		return -EINVAL;
1744
	}
1745

L
Linus Torvalds 已提交
1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756
	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);
1757 1758 1759 1760

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

L
Linus Torvalds 已提交
1761 1762 1763 1764
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1765 1766 1767 1768 1769 1770
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;
1771
	pgtable_t token;
1772
	spinlock_t *uninitialized_var(ptl);
1773 1774 1775 1776 1777 1778 1779 1780 1781

	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));

1782 1783
	arch_enter_lazy_mmu_mode();

1784
	token = pmd_pgtable(*pmd);
1785 1786

	do {
1787
		err = fn(pte, token, addr, data);
1788 1789 1790 1791
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

1792 1793
	arch_leave_lazy_mmu_mode();

1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806
	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
1807 1808
	BUG_ON(pud_huge(*pud));

1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849
	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
1850
	unsigned long start = addr, end = addr + size;
1851 1852 1853
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1854
	mmu_notifier_invalidate_range_start(mm, start, end);
1855 1856 1857 1858 1859 1860 1861
	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
1862
	mmu_notifier_invalidate_range_end(mm, start, end);
1863 1864 1865 1866
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1867 1868 1869 1870 1871 1872 1873 1874 1875
/*
 * 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
1876
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1877 1878 1879 1880 1881
				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
1882 1883
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1884
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1885
		spin_unlock(ptl);
1886 1887 1888 1889 1890 1891
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904
/*
 * 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;
}

1905
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1906 1907 1908 1909 1910 1911 1912 1913 1914
{
	/*
	 * 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
1915 1916 1917 1918 1919 1920 1921 1922 1923
		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))
1924 1925
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1926
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1927 1928
	} else
		copy_user_highpage(dst, src, va, vma);
1929 1930
}

L
Linus Torvalds 已提交
1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944
/*
 * 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.
 *
1945 1946 1947
 * 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
1948
 */
1949 1950
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1951
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1952
{
1953
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1954
	pte_t entry;
N
Nick Piggin 已提交
1955
	int reuse = 0, ret = 0;
1956
	int page_mkwrite = 0;
1957
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1958

1959
	old_page = vm_normal_page(vma, address, orig_pte);
1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970
	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;
1971
		goto gotten;
1972
	}
L
Linus Torvalds 已提交
1973

1974
	/*
P
Peter Zijlstra 已提交
1975 1976
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1977
	 */
H
Hugh Dickins 已提交
1978
	if (PageAnon(old_page) && !PageKsm(old_page)) {
1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990
		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
1991
		}
1992
		reuse = reuse_swap_page(old_page);
1993
		unlock_page(old_page);
P
Peter Zijlstra 已提交
1994
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1995
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1996 1997 1998 1999 2000
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
2001
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2002 2003 2004 2005 2006 2007 2008 2009 2010
			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;

2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
			/*
			 * 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);

2022 2023 2024 2025
			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
			if (unlikely(tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
				ret = tmp;
2026
				goto unwritable_page;
2027
			}
N
Nick Piggin 已提交
2028 2029 2030 2031 2032 2033 2034 2035 2036
			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));
2037 2038 2039 2040 2041 2042 2043 2044 2045

			/*
			 * 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
2046 2047 2048
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				page_cache_release(old_page);
2049
				goto unlock;
N
Nick Piggin 已提交
2050
			}
2051 2052

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2053
		}
2054 2055
		dirty_page = old_page;
		get_page(dirty_page);
2056 2057 2058 2059
		reuse = 1;
	}

	if (reuse) {
2060
reuse:
2061 2062 2063
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2064
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2065
			update_mmu_cache(vma, address, entry);
2066 2067
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
2068 2069 2070 2071 2072
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2073
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2074
gotten:
2075
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2076 2077

	if (unlikely(anon_vma_prepare(vma)))
2078
		goto oom;
N
Nick Piggin 已提交
2079 2080 2081 2082
	VM_BUG_ON(old_page == ZERO_PAGE(0));
	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
	if (!new_page)
		goto oom;
N
Nick Piggin 已提交
2083 2084 2085 2086
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
2087
	if ((vma->vm_flags & VM_LOCKED) && old_page) {
N
Nick Piggin 已提交
2088 2089 2090 2091
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
N
Nick Piggin 已提交
2092
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
2093
	__SetPageUptodate(new_page);
2094

K
KAMEZAWA Hiroyuki 已提交
2095
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2096 2097
		goto oom_free_new;

L
Linus Torvalds 已提交
2098 2099 2100
	/*
	 * Re-check the pte - we dropped the lock
	 */
2101
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2102
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2103 2104 2105 2106 2107 2108
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
2109
			inc_mm_counter(mm, anon_rss);
2110
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2111 2112
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2113 2114 2115 2116 2117 2118
		/*
		 * 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.
		 */
2119
		ptep_clear_flush(vma, address, page_table);
N
Nick Piggin 已提交
2120
		page_add_new_anon_rmap(new_page, vma, address);
2121 2122 2123 2124 2125 2126
		/*
		 * 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);
2127
		update_mmu_cache(vma, address, entry);
N
Nick Piggin 已提交
2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150
		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.
			 */
2151
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2152 2153
		}

L
Linus Torvalds 已提交
2154 2155
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2156
		ret |= VM_FAULT_WRITE;
2157 2158 2159
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2160 2161 2162 2163
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
2164
unlock:
2165
	pte_unmap_unlock(page_table, ptl);
2166
	if (dirty_page) {
2167 2168 2169 2170 2171 2172 2173 2174
		/*
		 * 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
2175 2176 2177 2178
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
			set_page_dirty_balance(dirty_page, page_mkwrite);
		}
2179
		put_page(dirty_page);
N
Nick Piggin 已提交
2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197
		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);
2198
	}
N
Nick Piggin 已提交
2199
	return ret;
2200
oom_free_new:
2201
	page_cache_release(new_page);
2202
oom:
N
Nick Piggin 已提交
2203 2204 2205 2206 2207
	if (old_page) {
		if (page_mkwrite) {
			unlock_page(old_page);
			page_cache_release(old_page);
		}
H
Hugh Dickins 已提交
2208
		page_cache_release(old_page);
N
Nick Piggin 已提交
2209
	}
L
Linus Torvalds 已提交
2210
	return VM_FAULT_OOM;
2211 2212 2213

unwritable_page:
	page_cache_release(old_page);
2214
	return ret;
L
Linus Torvalds 已提交
2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241
}

/*
 * 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
2242
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268
 * 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;

2269 2270
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2271
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2272 2273
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2274 2275
	 */

L
Linus Torvalds 已提交
2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286
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;
		}
	}

2287 2288
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2289
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2290

2291
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2292 2293 2294 2295 2296 2297
		/* 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 */
2298
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2299 2300 2301 2302 2303 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 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364
		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;
	}
}

/**
2365
 * 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
2366
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
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
 * @holebegin: byte in first page to unmap, relative to the start of
 * the underlying file.  This will be rounded down to a PAGE_SIZE
 * boundary.  Note that this is different from vmtruncate(), which
 * 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);

2403
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419
	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);

2420 2421 2422 2423
/**
 * vmtruncate - unmap mappings "freed" by truncate() syscall
 * @inode: inode of the file used
 * @offset: file offset to start truncating
L
Linus Torvalds 已提交
2424 2425 2426 2427 2428 2429 2430
 *
 * NOTE! We have to be ready to update the memory sharing
 * between the file and the memory map for a potential last
 * incomplete page.  Ugly, but necessary.
 */
int vmtruncate(struct inode * inode, loff_t offset)
{
C
Christoph Hellwig 已提交
2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441
	if (inode->i_size < offset) {
		unsigned long limit;

		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
		if (limit != RLIM_INFINITY && offset > limit)
			goto out_sig;
		if (offset > inode->i_sb->s_maxbytes)
			goto out_big;
		i_size_write(inode, offset);
	} else {
		struct address_space *mapping = inode->i_mapping;
L
Linus Torvalds 已提交
2442

C
Christoph Hellwig 已提交
2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464
		/*
		 * truncation of in-use swapfiles is disallowed - it would
		 * cause subsequent swapout to scribble on the now-freed
		 * blocks.
		 */
		if (IS_SWAPFILE(inode))
			return -ETXTBSY;
		i_size_write(inode, offset);

		/*
		 * unmap_mapping_range is called twice, first simply for
		 * efficiency so that truncate_inode_pages does fewer
		 * single-page unmaps.  However after this first call, and
		 * before truncate_inode_pages finishes, it is possible for
		 * private pages to be COWed, which remain after
		 * truncate_inode_pages finishes, hence the second
		 * unmap_mapping_range call must be made for correctness.
		 */
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
		truncate_inode_pages(mapping, offset);
		unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
	}
2465

A
Al Viro 已提交
2466
	if (inode->i_op->truncate)
L
Linus Torvalds 已提交
2467 2468
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2469

L
Linus Torvalds 已提交
2470 2471 2472 2473 2474 2475 2476
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2477 2478 2479 2480 2481 2482 2483 2484 2485
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
2486
	if (!inode->i_op->truncate_range)
2487 2488
		return -ENOSYS;

2489
	mutex_lock(&inode->i_mutex);
2490 2491 2492
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2493
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2494 2495
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2496
	mutex_unlock(&inode->i_mutex);
2497 2498 2499 2500

	return 0;
}

L
Linus Torvalds 已提交
2501
/*
2502 2503 2504
 * 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
2505
 */
2506 2507
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2508
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2509
{
2510
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2511
	struct page *page;
2512
	swp_entry_t entry;
L
Linus Torvalds 已提交
2513
	pte_t pte;
2514
	struct mem_cgroup *ptr = NULL;
N
Nick Piggin 已提交
2515
	int ret = 0;
L
Linus Torvalds 已提交
2516

H
Hugh Dickins 已提交
2517
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2518
		goto out;
2519 2520

	entry = pte_to_swp_entry(orig_pte);
2521 2522 2523 2524
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2525
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2526 2527
	page = lookup_swap_cache(entry);
	if (!page) {
H
Hugh Dickins 已提交
2528
		grab_swap_token(mm); /* Contend for token _before_ read-in */
2529 2530
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2531 2532
		if (!page) {
			/*
2533 2534
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2535
			 */
2536
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2537 2538
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2539
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2540
			goto unlock;
L
Linus Torvalds 已提交
2541 2542 2543 2544
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2545
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2546 2547
	}

2548 2549 2550
	lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

K
KAMEZAWA Hiroyuki 已提交
2551
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2552
		ret = VM_FAULT_OOM;
2553
		goto out_page;
2554 2555
	}

L
Linus Torvalds 已提交
2556
	/*
2557
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2558
	 */
2559
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2560
	if (unlikely(!pte_same(*page_table, orig_pte)))
2561 2562 2563 2564 2565
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2566 2567
	}

2568 2569 2570 2571 2572 2573 2574 2575
	/*
	 * 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.
2576 2577 2578 2579
	 * 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().
2580
	 */
L
Linus Torvalds 已提交
2581

2582
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2583
	pte = mk_pte(page, vma->vm_page_prot);
2584
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2585
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2586
		flags &= ~FAULT_FLAG_WRITE;
L
Linus Torvalds 已提交
2587 2588 2589 2590
	}
	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
	page_add_anon_rmap(page, vma, address);
2591 2592
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
2593

2594
	swap_free(entry);
N
Nick Piggin 已提交
2595
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2596
		try_to_free_swap(page);
2597 2598
	unlock_page(page);

2599
	if (flags & FAULT_FLAG_WRITE) {
2600 2601 2602
		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
2603 2604 2605 2606 2607
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2608
unlock:
2609
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2610 2611
out:
	return ret;
2612
out_nomap:
2613
	mem_cgroup_cancel_charge_swapin(ptr);
2614
	pte_unmap_unlock(page_table, ptl);
2615
out_page:
2616 2617
	unlock_page(page);
	page_cache_release(page);
2618
	return ret;
L
Linus Torvalds 已提交
2619 2620 2621
}

/*
2622 2623 2624
 * 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
2625
 */
2626 2627
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2628
		unsigned int flags)
L
Linus Torvalds 已提交
2629
{
2630 2631
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2632 2633
	pte_t entry;

N
Nick Piggin 已提交
2634 2635
	/* Allocate our own private page. */
	pte_unmap(page_table);
2636

N
Nick Piggin 已提交
2637 2638 2639 2640 2641
	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
2642
	__SetPageUptodate(page);
2643

K
KAMEZAWA Hiroyuki 已提交
2644
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2645 2646
		goto oom_free_page;

N
Nick Piggin 已提交
2647 2648
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2649

N
Nick Piggin 已提交
2650
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2651
	if (!pte_none(*page_table) || ksm_test_exit(mm))
N
Nick Piggin 已提交
2652
		goto release;
H
Hugh Dickins 已提交
2653

N
Nick Piggin 已提交
2654 2655
	inc_mm_counter(mm, anon_rss);
	page_add_new_anon_rmap(page, vma, address);
2656
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2657 2658

	/* No need to invalidate - it was non-present before */
2659 2660
	update_mmu_cache(vma, address, entry);
unlock:
2661
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2662
	return 0;
2663
release:
2664
	mem_cgroup_uncharge_page(page);
2665 2666
	page_cache_release(page);
	goto unlock;
2667
oom_free_page:
2668
	page_cache_release(page);
2669
oom:
L
Linus Torvalds 已提交
2670 2671 2672 2673
	return VM_FAULT_OOM;
}

/*
2674
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2675
 * tries to share with existing pages, but makes a separate copy if
2676 2677
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2678 2679 2680 2681
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2682
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2683
 * but allow concurrent faults), and pte neither mapped nor locked.
2684
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2685
 */
2686
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2687
		unsigned long address, pmd_t *pmd,
2688
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2689
{
2690
	pte_t *page_table;
2691
	spinlock_t *ptl;
N
Nick Piggin 已提交
2692
	struct page *page;
L
Linus Torvalds 已提交
2693 2694
	pte_t entry;
	int anon = 0;
2695
	int charged = 0;
2696
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2697 2698
	struct vm_fault vmf;
	int ret;
2699
	int page_mkwrite = 0;
2700

N
Nick Piggin 已提交
2701 2702 2703 2704
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2705

N
Nick Piggin 已提交
2706 2707 2708
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2709

2710
	/*
N
Nick Piggin 已提交
2711
	 * For consistency in subsequent calls, make the faulted page always
2712 2713
	 * locked.
	 */
N
Nick Piggin 已提交
2714
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2715
		lock_page(vmf.page);
2716
	else
N
Nick Piggin 已提交
2717
		VM_BUG_ON(!PageLocked(vmf.page));
2718

L
Linus Torvalds 已提交
2719 2720 2721
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2722
	page = vmf.page;
2723
	if (flags & FAULT_FLAG_WRITE) {
2724
		if (!(vma->vm_flags & VM_SHARED)) {
2725
			anon = 1;
2726
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2727
				ret = VM_FAULT_OOM;
2728
				goto out;
2729
			}
N
Nick Piggin 已提交
2730 2731
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2732
			if (!page) {
N
Nick Piggin 已提交
2733
				ret = VM_FAULT_OOM;
2734
				goto out;
2735
			}
K
KAMEZAWA Hiroyuki 已提交
2736
			if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2737 2738 2739 2740 2741
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
2742 2743 2744 2745 2746 2747
			/*
			 * 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
2748
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2749
			__SetPageUptodate(page);
2750
		} else {
2751 2752
			/*
			 * If the page will be shareable, see if the backing
2753
			 * address space wants to know that the page is about
2754 2755
			 * to become writable
			 */
2756
			if (vma->vm_ops->page_mkwrite) {
2757 2758
				int tmp;

2759
				unlock_page(page);
N
Nick Piggin 已提交
2760
				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2761 2762 2763 2764
				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
2765
					goto unwritable_page;
N
Nick Piggin 已提交
2766
				}
N
Nick Piggin 已提交
2767 2768 2769 2770 2771 2772 2773 2774 2775
				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));
2776
				page_mkwrite = 1;
2777 2778
			}
		}
2779

L
Linus Torvalds 已提交
2780 2781
	}

2782
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2783 2784 2785 2786 2787 2788

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
2789
	 * Note that if FAULT_FLAG_WRITE is set, we either now have
L
Linus Torvalds 已提交
2790 2791 2792 2793 2794
	 * 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... */
H
Hugh Dickins 已提交
2795
	if (likely(pte_same(*page_table, orig_pte) && !ksm_test_exit(mm))) {
2796 2797
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2798
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2799 2800
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
2801 2802
			inc_mm_counter(mm, anon_rss);
			page_add_new_anon_rmap(page, vma, address);
2803
		} else {
2804
			inc_mm_counter(mm, file_rss);
2805
			page_add_file_rmap(page);
2806
			if (flags & FAULT_FLAG_WRITE) {
2807
				dirty_page = page;
2808 2809
				get_page(dirty_page);
			}
2810
		}
2811
		set_pte_at(mm, address, page_table, entry);
2812 2813 2814

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2815
	} else {
2816 2817
		if (charged)
			mem_cgroup_uncharge_page(page);
2818 2819 2820
		if (anon)
			page_cache_release(page);
		else
2821
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2822 2823
	}

2824
	pte_unmap_unlock(page_table, ptl);
2825 2826

out:
N
Nick Piggin 已提交
2827 2828
	if (dirty_page) {
		struct address_space *mapping = page->mapping;
2829

N
Nick Piggin 已提交
2830 2831 2832
		if (set_page_dirty(dirty_page))
			page_mkwrite = 1;
		unlock_page(dirty_page);
2833
		put_page(dirty_page);
N
Nick Piggin 已提交
2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848
		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);
2849
	}
2850

N
Nick Piggin 已提交
2851
	return ret;
N
Nick Piggin 已提交
2852 2853 2854 2855

unwritable_page:
	page_cache_release(page);
	return ret;
2856
}
2857

2858 2859
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2860
		unsigned int flags, pte_t orig_pte)
2861 2862
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2863
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2864

2865 2866
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2867 2868
}

L
Linus Torvalds 已提交
2869 2870 2871 2872
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2873 2874 2875 2876
 *
 * 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
2877
 */
N
Nick Piggin 已提交
2878
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2879
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2880
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2881
{
2882
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2883

2884 2885
	flags |= FAULT_FLAG_NONLINEAR;

H
Hugh Dickins 已提交
2886
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2887
		return 0;
L
Linus Torvalds 已提交
2888

2889
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2890 2891 2892
		/*
		 * Page table corrupted: show pte and kill process.
		 */
2893
		print_bad_pte(vma, address, orig_pte, NULL);
2894 2895 2896 2897
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2898
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909
}

/*
 * 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
2910 2911 2912
 * 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
2913 2914
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2915
		struct vm_area_struct *vma, unsigned long address,
2916
		pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
2917 2918
{
	pte_t entry;
2919
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2920

2921
	entry = *pte;
L
Linus Torvalds 已提交
2922
	if (!pte_present(entry)) {
2923
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2924
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2925
				if (likely(vma->vm_ops->fault))
2926
					return do_linear_fault(mm, vma, address,
2927
						pte, pmd, flags, entry);
J
Jes Sorensen 已提交
2928 2929
			}
			return do_anonymous_page(mm, vma, address,
2930
						 pte, pmd, flags);
2931
		}
L
Linus Torvalds 已提交
2932
		if (pte_file(entry))
N
Nick Piggin 已提交
2933
			return do_nonlinear_fault(mm, vma, address,
2934
					pte, pmd, flags, entry);
2935
		return do_swap_page(mm, vma, address,
2936
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
2937 2938
	}

H
Hugh Dickins 已提交
2939
	ptl = pte_lockptr(mm, pmd);
2940 2941 2942
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
2943
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
2944
		if (!pte_write(entry))
2945 2946
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2947 2948 2949
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2950
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
2951 2952 2953 2954 2955 2956 2957 2958
		update_mmu_cache(vma, address, entry);
	} 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.
		 */
2959
		if (flags & FAULT_FLAG_WRITE)
2960 2961
			flush_tlb_page(vma, address);
	}
2962 2963
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2964
	return 0;
L
Linus Torvalds 已提交
2965 2966 2967 2968 2969
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2970
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2971
		unsigned long address, unsigned int flags)
L
Linus Torvalds 已提交
2972 2973 2974 2975 2976 2977 2978 2979
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2980
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2981

2982
	if (unlikely(is_vm_hugetlb_page(vma)))
2983
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
2984 2985 2986 2987

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2988
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2989 2990
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2991
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2992 2993
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2994
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2995

2996
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
2997 2998 2999 3000 3001
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3002
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3003
 */
3004
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3005
{
H
Hugh Dickins 已提交
3006 3007
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3008
		return -ENOMEM;
L
Linus Torvalds 已提交
3009

3010 3011
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3012
	spin_lock(&mm->page_table_lock);
3013
	if (pgd_present(*pgd))		/* Another has populated it */
3014
		pud_free(mm, new);
3015 3016
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3017
	spin_unlock(&mm->page_table_lock);
3018
	return 0;
L
Linus Torvalds 已提交
3019 3020 3021 3022 3023 3024
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3025
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3026
 */
3027
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3028
{
H
Hugh Dickins 已提交
3029 3030
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3031
		return -ENOMEM;
L
Linus Torvalds 已提交
3032

3033 3034
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3035
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3036
#ifndef __ARCH_HAS_4LEVEL_HACK
3037
	if (pud_present(*pud))		/* Another has populated it */
3038
		pmd_free(mm, new);
3039 3040
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3041
#else
3042
	if (pgd_present(*pud))		/* Another has populated it */
3043
		pmd_free(mm, new);
3044 3045
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3046
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3047
	spin_unlock(&mm->page_table_lock);
3048
	return 0;
3049
}
L
Linus Torvalds 已提交
3050 3051 3052 3053 3054 3055 3056 3057 3058
#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
3059
		return -ENOMEM;
L
Linus Torvalds 已提交
3060
	write = (vma->vm_flags & VM_WRITE) != 0;
3061 3062
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
3063
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
3064 3065
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
3066
	if (ret < 0)
L
Linus Torvalds 已提交
3067
		return ret;
3068
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
3069 3070 3071 3072 3073
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
3074
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
3075 3076 3077 3078 3079 3080

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
3081 3082
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
3083 3084 3085 3086 3087 3088 3089
	/*
	 * 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
3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113
	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 */
3114

J
Johannes Weiner 已提交
3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151
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
3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180
/**
 * 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);

3181
#ifdef CONFIG_HAVE_IOREMAP_PROT
3182 3183 3184
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3185
{
3186
	int ret = -EINVAL;
3187 3188 3189
	pte_t *ptep, pte;
	spinlock_t *ptl;

3190 3191
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3192

3193
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3194
		goto out;
3195
	pte = *ptep;
3196

3197 3198 3199 3200
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3201
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3202

3203
	ret = 0;
3204 3205 3206
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3207
	return ret;
3208 3209 3210 3211 3212 3213 3214
}

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
3215
	void __iomem *maddr;
3216 3217
	int offset = addr & (PAGE_SIZE-1);

3218
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231
		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

3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247
/*
 * 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
3248
	/* ignore errors, just check how much was successfully transferred */
3249 3250 3251
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3252
		struct page *page = NULL;
3253 3254 3255

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271
		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;
3272
		} else {
3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288
			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);
3289 3290 3291 3292 3293 3294 3295 3296 3297 3298
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
3299 3300 3301 3302 3303 3304 3305 3306 3307

/*
 * 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;

3308 3309 3310 3311 3312 3313 3314
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3315 3316 3317 3318 3319 3320 3321 3322
	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;

3323
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336
			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);
}
3337 3338 3339 3340

#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
3341 3342 3343 3344 3345 3346 3347 3348 3349
	/*
	 * 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;

3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360
	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