memory.c 82.6 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>
#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 <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>

#include <linux/swapops.h>
#include <linux/elf.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)
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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);
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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);
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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);
	pmd_free_tlb(tlb, pmd);
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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);
	pud_free_tlb(tlb, pud);
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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, pte_t pte,
			  unsigned long vaddr)
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{
	printk(KERN_ERR "Bad pte = %08llx, process = %s, "
			"vm_flags = %lx, vaddr = %lx\n",
		(long long)pte_val(pte),
		(vma->vm_mm == current->mm ? current->comm : "???"),
		vma->vm_flags, vaddr);
	dump_stack();
}

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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;

	if (HAVE_PTE_SPECIAL) {
		if (likely(!pte_special(pte))) {
			VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
			return pte_page(pte);
		}
		VM_BUG_ON(!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)));
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

	pfn = pte_pfn(pte);
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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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	VM_BUG_ON(!pfn_valid(pfn));
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	/*
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	 * NOTE! We still have PageReserved() pages in the page tables.
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	 *
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	 * 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);
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				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
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				spin_unlock(&mmlist_lock);
			}
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			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);
			}
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		}
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		goto out_set_pte;
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	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
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	if (is_cow_mapping(vm_flags)) {
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		ptep_set_wrprotect(src_mm, addr, src_pte);
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		pte = pte_wrprotect(pte);
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	}

	/*
	 * 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);
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	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
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		page_dup_rmap(page, vma, addr);
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		rss[!!PageAnon(page)]++;
	}
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out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
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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;
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	spinlock_t *src_ptl, *dst_ptl;
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	int progress = 0;
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	int rss[2];
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again:
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	rss[1] = rss[0] = 0;
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Hugh Dickins 已提交
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	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
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	if (!dst_pte)
		return -ENOMEM;
	src_pte = pte_offset_map_nested(src_pmd, addr);
H
Hugh Dickins 已提交
571
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
572
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
573
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
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	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
580 581 582
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
583
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
584 585
				break;
		}
L
Linus Torvalds 已提交
586 587 588 589
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
590
		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);

594
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
595
	spin_unlock(src_ptl);
L
Linus Torvalds 已提交
596
	pte_unmap_nested(src_pte - 1);
597
	add_mm_rss(dst_mm, rss[0], rss[1]);
H
Hugh Dickins 已提交
598 599
	pte_unmap_unlock(dst_pte - 1, dst_ptl);
	cond_resched();
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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
656
	int ret;
L
Linus Torvalds 已提交
657

658 659 660 661 662 663
	/*
	 * 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.
	 */
664
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
665 666 667 668
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
669 670 671
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

672
	if (unlikely(is_pfn_mapping(vma))) {
673 674 675 676 677 678 679 680 681
		/*
		 * 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
682 683 684 685 686 687 688 689 690 691
	/*
	 * 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
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	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;
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Andrea Arcangeli 已提交
698 699 700 701 702
		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
703
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
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Andrea Arcangeli 已提交
704 705 706 707 708

	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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}

711
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
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				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
713
				unsigned long addr, unsigned long end,
714
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
715
{
N
Nick Piggin 已提交
716
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
717
	pte_t *pte;
718
	spinlock_t *ptl;
719 720
	int file_rss = 0;
	int anon_rss = 0;
L
Linus Torvalds 已提交
721

722
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
723
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
724 725
	do {
		pte_t ptent = *pte;
726 727
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
728
			continue;
729
		}
730 731 732

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
733
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
734
			struct page *page;
735

736
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754
			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
755
			ptent = ptep_get_and_clear_full(mm, addr, pte,
756
							tlb->fullmm);
L
Linus Torvalds 已提交
757 758 759 760 761 762
			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
763
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
764 765
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
H
Hugh Dickins 已提交
766
				anon_rss--;
767 768 769
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
770 771
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
772
					mark_page_accessed(page);
H
Hugh Dickins 已提交
773
				file_rss--;
774
			}
N
Nick Piggin 已提交
775
			page_remove_rmap(page, vma);
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Linus Torvalds 已提交
776 777 778 779 780 781 782 783 784 785 786
			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;
		if (!pte_file(ptent))
			free_swap_and_cache(pte_to_swp_entry(ptent));
787
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
788
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
789

H
Hugh Dickins 已提交
790
	add_mm_rss(mm, file_rss, anon_rss);
791
	arch_leave_lazy_mmu_mode();
792
	pte_unmap_unlock(pte - 1, ptl);
793 794

	return addr;
L
Linus Torvalds 已提交
795 796
}

797
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
798
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
799
				unsigned long addr, unsigned long end,
800
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
801 802 803 804 805 806 807
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
808 809
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
810
			continue;
811 812 813 814 815 816
		}
		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
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}

819
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
820
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
821
				unsigned long addr, unsigned long end,
822
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
823 824 825 826 827 828 829
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
830 831
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
832
			continue;
833 834 835 836 837 838
		}
		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
839 840
}

841 842
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
843
				unsigned long addr, unsigned long end,
844
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
845 846 847 848 849 850 851 852 853 854 855 856
{
	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);
857 858
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
859
			continue;
860 861 862 863
		}
		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
864
	tlb_end_vma(tlb, vma);
865 866

	return addr;
L
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867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884
}

#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
 *
885
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
886
 *
887
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
888
 *
889 890
 * 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
891 892 893 894 895 896 897 898 899 900 901
 * 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.
 */
902
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
903 904 905 906
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
907
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
908 909
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
910
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
911
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
912
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
913
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
914

A
Andrea Arcangeli 已提交
915
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
916 917 918 919 920 921 922 923 924 925 926 927 928
	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;

929
		if (unlikely(is_pfn_mapping(vma)))
930 931
			untrack_pfn_vma(vma, 0, 0);

L
Linus Torvalds 已提交
932 933 934 935 936 937
		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

938
			if (unlikely(is_vm_hugetlb_page(vma))) {
939 940 941 942 943 944 945 946 947 948 949 950 951 952
				/*
				 * 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) /
953
					pages_per_huge_page(hstate_vma(vma));
954 955
				}

956 957 958 959 960 961 962 963
				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
964 965 966 967 968
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
969
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
970
				if (i_mmap_lock) {
971
					*tlbp = NULL;
L
Linus Torvalds 已提交
972 973 974 975 976
					goto out;
				}
				cond_resched();
			}

977
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
978
			tlb_start_valid = 0;
979
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
980 981 982
		}
	}
out:
A
Andrea Arcangeli 已提交
983
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
984
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
985 986 987 988 989 990 991 992 993
}

/**
 * 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
 */
994
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
995 996 997 998 999 1000 1001 1002 1003
		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);
1004
	update_hiwater_rss(mm);
1005 1006 1007
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
1008
	return end;
L
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1009 1010
}

1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033
/**
 * 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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1034 1035 1036
/*
 * Do a quick page-table lookup for a single page.
 */
1037
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1038
			unsigned int flags)
L
Linus Torvalds 已提交
1039 1040 1041 1042 1043
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1044
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1045
	struct page *page;
1046
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1047

1048 1049 1050 1051 1052
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
L
Linus Torvalds 已提交
1053

1054
	page = NULL;
L
Linus Torvalds 已提交
1055 1056
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1057
		goto no_page_table;
L
Linus Torvalds 已提交
1058 1059

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1060
	if (pud_none(*pud))
1061
		goto no_page_table;
A
Andi Kleen 已提交
1062 1063 1064 1065 1066 1067 1068 1069
	if (pud_huge(*pud)) {
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
		goto out;
	}
	if (unlikely(pud_bad(*pud)))
		goto no_page_table;

L
Linus Torvalds 已提交
1070
	pmd = pmd_offset(pud, address);
1071
	if (pmd_none(*pmd))
1072 1073 1074 1075
		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
1076
		goto out;
1077
	}
1078 1079 1080
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1081
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1082 1083

	pte = *ptep;
1084
	if (!pte_present(pte))
1085
		goto no_page;
1086 1087
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
1088 1089
	page = vm_normal_page(vma, address, pte);
	if (unlikely(!page))
1090
		goto bad_page;
L
Linus Torvalds 已提交
1091

1092 1093 1094 1095 1096 1097 1098 1099 1100 1101
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
		mark_page_accessed(page);
	}
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1102
out:
1103
	return page;
L
Linus Torvalds 已提交
1104

1105 1106 1107 1108 1109 1110 1111 1112 1113
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 */
1114 1115 1116 1117 1118 1119
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
1120
		page = ZERO_PAGE(0);
1121 1122 1123 1124 1125
		if (flags & FOLL_GET)
			get_page(page);
		BUG_ON(flags & FOLL_WRITE);
	}
	return page;
L
Linus Torvalds 已提交
1126 1127
}

1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140
/* 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
1141
	 * And if we have a fault routine, it's not an anonymous region.
1142
	 */
N
Nick Piggin 已提交
1143
	return !vma->vm_ops || !vma->vm_ops->fault;
1144 1145
}

N
Nick Piggin 已提交
1146 1147 1148 1149


int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		     unsigned long start, int len, int flags,
L
Linus Torvalds 已提交
1150 1151 1152
		struct page **pages, struct vm_area_struct **vmas)
{
	int i;
N
Nick Piggin 已提交
1153 1154 1155 1156
	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);
L
Linus Torvalds 已提交
1157

1158 1159
	if (len <= 0)
		return 0;
L
Linus Torvalds 已提交
1160 1161 1162 1163
	/* 
	 * Require read or write permissions.
	 * If 'force' is set, we only require the "MAY" flags.
	 */
1164 1165
	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
Linus Torvalds 已提交
1166 1167 1168
	i = 0;

	do {
1169 1170
		struct vm_area_struct *vma;
		unsigned int foll_flags;
L
Linus Torvalds 已提交
1171 1172 1173 1174 1175 1176 1177 1178 1179

		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
1180 1181 1182

			/* user gate pages are read-only */
			if (!ignore && write)
L
Linus Torvalds 已提交
1183 1184 1185 1186 1187 1188 1189 1190 1191
				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);
1192 1193
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
L
Linus Torvalds 已提交
1194
			pte = pte_offset_map(pmd, pg);
1195 1196 1197 1198
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
L
Linus Torvalds 已提交
1199
			if (pages) {
1200
				struct page *page = vm_normal_page(gate_vma, start, *pte);
1201 1202 1203
				pages[i] = page;
				if (page)
					get_page(page);
L
Linus Torvalds 已提交
1204 1205 1206 1207 1208 1209 1210 1211 1212 1213
			}
			pte_unmap(pte);
			if (vmas)
				vmas[i] = gate_vma;
			i++;
			start += PAGE_SIZE;
			len--;
			continue;
		}

N
Nick Piggin 已提交
1214 1215 1216
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
		    (!ignore && !(vm_flags & vma->vm_flags)))
L
Linus Torvalds 已提交
1217 1218 1219 1220
			return i ? : -EFAULT;

		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
1221
						&start, &len, i, write);
L
Linus Torvalds 已提交
1222 1223
			continue;
		}
1224 1225 1226 1227

		foll_flags = FOLL_TOUCH;
		if (pages)
			foll_flags |= FOLL_GET;
1228
		if (!write && use_zero_page(vma))
1229 1230
			foll_flags |= FOLL_ANON;

L
Linus Torvalds 已提交
1231
		do {
1232
			struct page *page;
L
Linus Torvalds 已提交
1233

1234 1235 1236 1237 1238 1239
			/*
			 * If tsk is ooming, cut off its access to large memory
			 * allocations. It has a pending SIGKILL, but it can't
			 * be processed until returning to user space.
			 */
			if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
1240
				return i ? i : -ENOMEM;
1241

1242 1243
			if (write)
				foll_flags |= FOLL_WRITE;
1244

1245
			cond_resched();
1246
			while (!(page = follow_page(vma, start, foll_flags))) {
1247
				int ret;
N
Nick Piggin 已提交
1248
				ret = handle_mm_fault(mm, vma, start,
1249
						foll_flags & FOLL_WRITE);
N
Nick Piggin 已提交
1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261
				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++;

1262
				/*
N
Nick Piggin 已提交
1263 1264 1265 1266 1267
				 * 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
				 * page lookups as if they were reads.
1268 1269
				 */
				if (ret & VM_FAULT_WRITE)
1270
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1271

1272
				cond_resched();
L
Linus Torvalds 已提交
1273
			}
1274 1275
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1276
			if (pages) {
1277
				pages[i] = page;
1278

1279
				flush_anon_page(vma, page, start);
1280
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1281 1282 1283 1284 1285 1286
			}
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
			len--;
1287 1288
		} while (len && start < vma->vm_end);
	} while (len);
L
Linus Torvalds 已提交
1289 1290
	return i;
}
N
Nick Piggin 已提交
1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307

int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long start, int len, int write, int force,
		struct page **pages, struct vm_area_struct **vmas)
{
	int flags = 0;

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

	return __get_user_pages(tsk, mm,
				start, len, flags,
				pages, vmas);
}

L
Linus Torvalds 已提交
1308 1309
EXPORT_SYMBOL(get_user_pages);

H
Harvey Harrison 已提交
1310 1311
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
			spinlock_t **ptl)
1312 1313 1314 1315
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1316
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1317 1318 1319 1320 1321 1322
		if (pmd)
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
	}
	return NULL;
}

1323 1324 1325 1326 1327 1328 1329
/*
 * 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
1330 1331
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1332
{
N
Nick Piggin 已提交
1333
	struct mm_struct *mm = vma->vm_mm;
1334
	int retval;
1335
	pte_t *pte;
1336 1337
	spinlock_t *ptl;

1338
	retval = -EINVAL;
1339
	if (PageAnon(page))
1340
		goto out;
1341 1342
	retval = -ENOMEM;
	flush_dcache_page(page);
1343
	pte = get_locked_pte(mm, addr, &ptl);
1344
	if (!pte)
1345
		goto out;
1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356
	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;
1357 1358
	pte_unmap_unlock(pte, ptl);
	return retval;
1359 1360 1361 1362 1363 1364
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1365 1366 1367 1368 1369 1370
/**
 * 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
 *
1371 1372 1373 1374 1375 1376
 * 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
1377
 * (see split_page()).
1378 1379 1380 1381 1382 1383 1384 1385 1386
 *
 * 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
1387 1388
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1389 1390 1391 1392 1393
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1394
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1395
	return insert_page(vma, addr, page, vma->vm_page_prot);
1396
}
1397
EXPORT_SYMBOL(vm_insert_page);
1398

N
Nick Piggin 已提交
1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426
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
1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437
/**
 * 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
1438 1439 1440 1441 1442
 *
 * 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
1443 1444
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1445
			unsigned long pfn)
N
Nick Piggin 已提交
1446
{
1447
	int ret;
N
Nick Piggin 已提交
1448 1449 1450 1451 1452 1453
	/*
	 * 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
1454 1455 1456 1457 1458
	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
1459

N
Nick Piggin 已提交
1460 1461
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1462 1463 1464 1465 1466 1467 1468 1469 1470
	if (track_pfn_vma_new(vma, vma->vm_page_prot, pfn, PAGE_SIZE))
		return -EINVAL;

	ret = insert_pfn(vma, addr, pfn, vma->vm_page_prot);

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

	return ret;
N
Nick Piggin 已提交
1471 1472
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1473

N
Nick Piggin 已提交
1474 1475 1476 1477
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
1478

N
Nick Piggin 已提交
1479 1480
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1481

N
Nick Piggin 已提交
1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494
	/*
	 * 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
1495
}
N
Nick Piggin 已提交
1496
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1497

L
Linus Torvalds 已提交
1498 1499 1500 1501 1502 1503 1504 1505 1506 1507
/*
 * 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
1508
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1509

H
Hugh Dickins 已提交
1510
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1511 1512
	if (!pte)
		return -ENOMEM;
1513
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1514 1515
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1516
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1517 1518
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1519
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1520
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563
	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;
}

1564 1565 1566 1567 1568 1569 1570 1571 1572 1573
/**
 * 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
1574 1575 1576 1577 1578
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;
1579
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1580 1581 1582 1583 1584 1585 1586 1587
	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
1588 1589 1590 1591 1592
	 *   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.
1593 1594 1595
	 *   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
1596 1597 1598 1599
	 *
	 * 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
1600
	 */
1601
	if (addr == vma->vm_start && end == vma->vm_end)
L
Linus Torvalds 已提交
1602
		vma->vm_pgoff = pfn;
1603 1604
	else if (is_cow_mapping(vma->vm_flags))
		return -EINVAL;
L
Linus Torvalds 已提交
1605

1606
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
1607

1608 1609 1610 1611
	err = track_pfn_vma_new(vma, prot, pfn, PAGE_ALIGN(size));
	if (err)
		return -EINVAL;

L
Linus Torvalds 已提交
1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622
	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);
1623 1624 1625 1626

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

L
Linus Torvalds 已提交
1627 1628 1629 1630
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1631 1632 1633 1634 1635 1636
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;
1637
	pgtable_t token;
1638
	spinlock_t *uninitialized_var(ptl);
1639 1640 1641 1642 1643 1644 1645 1646 1647

	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));

1648
	token = pmd_pgtable(*pmd);
1649 1650

	do {
1651
		err = fn(pte, token, addr, data);
1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668
		if (err)
			break;
	} while (pte++, addr += PAGE_SIZE, addr != end);

	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
1669 1670
	BUG_ON(pud_huge(*pud));

1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711
	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
1712
	unsigned long start = addr, end = addr + size;
1713 1714 1715
	int err;

	BUG_ON(addr >= end);
A
Andrea Arcangeli 已提交
1716
	mmu_notifier_invalidate_range_start(mm, start, end);
1717 1718 1719 1720 1721 1722 1723
	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
1724
	mmu_notifier_invalidate_range_end(mm, start, end);
1725 1726 1727 1728
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1729 1730 1731 1732 1733 1734 1735 1736 1737
/*
 * 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
1738
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1739 1740 1741 1742 1743
				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
1744 1745
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1746
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1747
		spin_unlock(ptl);
1748 1749 1750 1751 1752 1753
	}
#endif
	pte_unmap(page_table);
	return same;
}

L
Linus Torvalds 已提交
1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766
/*
 * 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;
}

1767
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1768 1769 1770 1771 1772 1773 1774 1775 1776
{
	/*
	 * 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
1777 1778 1779 1780 1781 1782 1783 1784 1785
		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))
1786 1787
			memset(kaddr, 0, PAGE_SIZE);
		kunmap_atomic(kaddr, KM_USER0);
1788
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1789 1790
	} else
		copy_user_highpage(dst, src, va, vma);
1791 1792
}

L
Linus Torvalds 已提交
1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806
/*
 * 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.
 *
1807 1808 1809
 * 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
1810
 */
1811 1812
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
1813
		spinlock_t *ptl, pte_t orig_pte)
L
Linus Torvalds 已提交
1814
{
1815
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
1816
	pte_t entry;
N
Nick Piggin 已提交
1817
	int reuse = 0, ret = 0;
1818
	int page_mkwrite = 0;
1819
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
1820

1821
	old_page = vm_normal_page(vma, address, orig_pte);
1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832
	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;
1833
		goto gotten;
1834
	}
L
Linus Torvalds 已提交
1835

1836
	/*
P
Peter Zijlstra 已提交
1837 1838
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
1839
	 */
P
Peter Zijlstra 已提交
1840
	if (PageAnon(old_page)) {
N
Nick Piggin 已提交
1841
		if (trylock_page(old_page)) {
P
Peter Zijlstra 已提交
1842 1843 1844 1845
			reuse = can_share_swap_page(old_page);
			unlock_page(old_page);
		}
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
1846
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
1847 1848 1849 1850 1851
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
			/*
			 * 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);

			if (vma->vm_ops->page_mkwrite(vma, old_page) < 0)
				goto unwritable_page;

			/*
			 * 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);
1875
			page_cache_release(old_page);
1876 1877
			if (!pte_same(*page_table, orig_pte))
				goto unlock;
1878 1879

			page_mkwrite = 1;
L
Linus Torvalds 已提交
1880
		}
1881 1882
		dirty_page = old_page;
		get_page(dirty_page);
1883 1884 1885 1886
		reuse = 1;
	}

	if (reuse) {
1887
reuse:
1888 1889 1890
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1891
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
1892
			update_mmu_cache(vma, address, entry);
1893 1894
		ret |= VM_FAULT_WRITE;
		goto unlock;
L
Linus Torvalds 已提交
1895 1896 1897 1898 1899
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
1900
	page_cache_get(old_page);
H
Hugh Dickins 已提交
1901
gotten:
1902
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
1903 1904

	if (unlikely(anon_vma_prepare(vma)))
1905
		goto oom;
N
Nick Piggin 已提交
1906 1907 1908 1909
	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
1910 1911 1912 1913 1914 1915 1916 1917 1918
	/*
	 * Don't let another task, with possibly unlocked vma,
	 * keep the mlocked page.
	 */
	if (vma->vm_flags & VM_LOCKED) {
		lock_page(old_page);	/* for LRU manipulation */
		clear_page_mlock(old_page);
		unlock_page(old_page);
	}
N
Nick Piggin 已提交
1919
	cow_user_page(new_page, old_page, address, vma);
N
Nick Piggin 已提交
1920
	__SetPageUptodate(new_page);
1921

1922
	if (mem_cgroup_charge(new_page, mm, GFP_KERNEL))
1923 1924
		goto oom_free_new;

L
Linus Torvalds 已提交
1925 1926 1927
	/*
	 * Re-check the pte - we dropped the lock
	 */
1928
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1929
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
1930 1931 1932 1933 1934 1935
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter(mm, file_rss);
				inc_mm_counter(mm, anon_rss);
			}
		} else
1936
			inc_mm_counter(mm, anon_rss);
1937
		flush_cache_page(vma, address, pte_pfn(orig_pte));
1938 1939
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1940 1941 1942 1943 1944 1945
		/*
		 * 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.
		 */
A
Andrea Arcangeli 已提交
1946
		ptep_clear_flush_notify(vma, address, page_table);
R
Rik van Riel 已提交
1947
		SetPageSwapBacked(new_page);
1948
		lru_cache_add_active_or_unevictable(new_page, vma);
N
Nick Piggin 已提交
1949
		page_add_new_anon_rmap(new_page, vma, address);
L
Linus Torvalds 已提交
1950

1951 1952 1953
//TODO:  is this safe?  do_anonymous_page() does it this way.
		set_pte_at(mm, address, page_table, entry);
		update_mmu_cache(vma, address, entry);
N
Nick Piggin 已提交
1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979
		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.
			 */
			page_remove_rmap(old_page, vma);
		}

L
Linus Torvalds 已提交
1980 1981
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
1982
		ret |= VM_FAULT_WRITE;
1983 1984 1985
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
1986 1987 1988 1989
	if (new_page)
		page_cache_release(new_page);
	if (old_page)
		page_cache_release(old_page);
1990
unlock:
1991
	pte_unmap_unlock(page_table, ptl);
1992
	if (dirty_page) {
1993 1994 1995
		if (vma->vm_file)
			file_update_time(vma->vm_file);

1996 1997 1998 1999 2000 2001 2002 2003 2004
		/*
		 * 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.
		 */
		wait_on_page_locked(dirty_page);
2005
		set_page_dirty_balance(dirty_page, page_mkwrite);
2006 2007
		put_page(dirty_page);
	}
N
Nick Piggin 已提交
2008
	return ret;
2009
oom_free_new:
2010
	page_cache_release(new_page);
2011
oom:
H
Hugh Dickins 已提交
2012 2013
	if (old_page)
		page_cache_release(old_page);
L
Linus Torvalds 已提交
2014
	return VM_FAULT_OOM;
2015 2016 2017 2018

unwritable_page:
	page_cache_release(old_page);
	return VM_FAULT_SIGBUS;
L
Linus Torvalds 已提交
2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045
}

/*
 * 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
2046
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072
 * 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;

2073 2074
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2075
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2076 2077
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2078 2079
	 */

L
Linus Torvalds 已提交
2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090
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;
		}
	}

2091 2092
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2093
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2094

2095
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2096 2097 2098 2099 2100 2101
		/* 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 */
2102
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168
		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;
	}
}

/**
2169
 * 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
2170
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206
 * @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);

2207
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223
	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);

2224 2225 2226 2227
/**
 * 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
2228 2229 2230 2231 2232 2233 2234
 *
 * 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
2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245
	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
2246

C
Christoph Hellwig 已提交
2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268
		/*
		 * 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);
	}
2269

A
Al Viro 已提交
2270
	if (inode->i_op->truncate)
L
Linus Torvalds 已提交
2271 2272
		inode->i_op->truncate(inode);
	return 0;
C
Christoph Hellwig 已提交
2273

L
Linus Torvalds 已提交
2274 2275 2276 2277 2278 2279 2280
out_sig:
	send_sig(SIGXFSZ, current, 0);
out_big:
	return -EFBIG;
}
EXPORT_SYMBOL(vmtruncate);

2281 2282 2283 2284 2285 2286 2287 2288 2289
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
2290
	if (!inode->i_op->truncate_range)
2291 2292
		return -ENOSYS;

2293
	mutex_lock(&inode->i_mutex);
2294 2295 2296
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2297
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2298 2299
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2300
	mutex_unlock(&inode->i_mutex);
2301 2302 2303 2304

	return 0;
}

L
Linus Torvalds 已提交
2305
/*
2306 2307 2308
 * 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
2309
 */
2310 2311 2312
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2313
{
2314
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2315
	struct page *page;
2316
	swp_entry_t entry;
L
Linus Torvalds 已提交
2317
	pte_t pte;
N
Nick Piggin 已提交
2318
	int ret = 0;
L
Linus Torvalds 已提交
2319

H
Hugh Dickins 已提交
2320
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2321
		goto out;
2322 2323

	entry = pte_to_swp_entry(orig_pte);
2324 2325 2326 2327
	if (is_migration_entry(entry)) {
		migration_entry_wait(mm, pmd, address);
		goto out;
	}
2328
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2329 2330
	page = lookup_swap_cache(entry);
	if (!page) {
2331
		grab_swap_token(); /* Contend for token _before_ read-in */
2332 2333
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2334 2335
		if (!page) {
			/*
2336 2337
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2338
			 */
2339
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2340 2341
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2342
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2343
			goto unlock;
L
Linus Torvalds 已提交
2344 2345 2346 2347
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2348
		count_vm_event(PGMAJFAULT);
L
Linus Torvalds 已提交
2349 2350
	}

2351 2352 2353 2354 2355
	mark_page_accessed(page);

	lock_page(page);
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);

2356
	if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
2357
		ret = VM_FAULT_OOM;
2358
		unlock_page(page);
2359 2360 2361
		goto out;
	}

L
Linus Torvalds 已提交
2362
	/*
2363
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2364
	 */
2365
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2366
	if (unlikely(!pte_same(*page_table, orig_pte)))
2367 2368 2369 2370 2371
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2372 2373 2374 2375
	}

	/* The page isn't present yet, go ahead with the fault. */

2376
	inc_mm_counter(mm, anon_rss);
L
Linus Torvalds 已提交
2377 2378 2379 2380 2381 2382 2383 2384 2385 2386
	pte = mk_pte(page, vma->vm_page_prot);
	if (write_access && can_share_swap_page(page)) {
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
		write_access = 0;
	}

	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
	page_add_anon_rmap(page, vma, address);

2387
	swap_free(entry);
N
Nick Piggin 已提交
2388
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2389 2390 2391
		remove_exclusive_swap_page(page);
	unlock_page(page);

L
Linus Torvalds 已提交
2392
	if (write_access) {
2393 2394 2395
		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
2396 2397 2398 2399 2400
		goto out;
	}

	/* No need to invalidate - it was non-present before */
	update_mmu_cache(vma, address, pte);
2401
unlock:
2402
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2403 2404
out:
	return ret;
2405
out_nomap:
2406
	mem_cgroup_uncharge_page(page);
2407
	pte_unmap_unlock(page_table, ptl);
2408 2409
	unlock_page(page);
	page_cache_release(page);
2410
	return ret;
L
Linus Torvalds 已提交
2411 2412 2413
}

/*
2414 2415 2416
 * 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
2417
 */
2418 2419 2420
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access)
L
Linus Torvalds 已提交
2421
{
2422 2423
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2424 2425
	pte_t entry;

N
Nick Piggin 已提交
2426 2427
	/* Allocate our own private page. */
	pte_unmap(page_table);
2428

N
Nick Piggin 已提交
2429 2430 2431 2432 2433
	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
2434
	__SetPageUptodate(page);
2435

2436
	if (mem_cgroup_charge(page, mm, GFP_KERNEL))
2437 2438
		goto oom_free_page;

N
Nick Piggin 已提交
2439 2440
	entry = mk_pte(page, vma->vm_page_prot);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
L
Linus Torvalds 已提交
2441

N
Nick Piggin 已提交
2442 2443 2444 2445
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!pte_none(*page_table))
		goto release;
	inc_mm_counter(mm, anon_rss);
R
Rik van Riel 已提交
2446
	SetPageSwapBacked(page);
2447
	lru_cache_add_active_or_unevictable(page, vma);
N
Nick Piggin 已提交
2448
	page_add_new_anon_rmap(page, vma, address);
2449
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2450 2451

	/* No need to invalidate - it was non-present before */
2452 2453
	update_mmu_cache(vma, address, entry);
unlock:
2454
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2455
	return 0;
2456
release:
2457
	mem_cgroup_uncharge_page(page);
2458 2459
	page_cache_release(page);
	goto unlock;
2460
oom_free_page:
2461
	page_cache_release(page);
2462
oom:
L
Linus Torvalds 已提交
2463 2464 2465 2466
	return VM_FAULT_OOM;
}

/*
2467
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
2468
 * tries to share with existing pages, but makes a separate copy if
2469 2470
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
2471 2472 2473 2474
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
2475
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2476
 * but allow concurrent faults), and pte neither mapped nor locked.
2477
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2478
 */
2479
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2480
		unsigned long address, pmd_t *pmd,
2481
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2482
{
2483
	pte_t *page_table;
2484
	spinlock_t *ptl;
N
Nick Piggin 已提交
2485
	struct page *page;
L
Linus Torvalds 已提交
2486 2487
	pte_t entry;
	int anon = 0;
2488
	int charged = 0;
2489
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
2490 2491
	struct vm_fault vmf;
	int ret;
2492
	int page_mkwrite = 0;
2493

N
Nick Piggin 已提交
2494 2495 2496 2497
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
2498

N
Nick Piggin 已提交
2499 2500 2501
	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
L
Linus Torvalds 已提交
2502

2503
	/*
N
Nick Piggin 已提交
2504
	 * For consistency in subsequent calls, make the faulted page always
2505 2506
	 * locked.
	 */
N
Nick Piggin 已提交
2507
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
2508
		lock_page(vmf.page);
2509
	else
N
Nick Piggin 已提交
2510
		VM_BUG_ON(!PageLocked(vmf.page));
2511

L
Linus Torvalds 已提交
2512 2513 2514
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
2515
	page = vmf.page;
2516
	if (flags & FAULT_FLAG_WRITE) {
2517
		if (!(vma->vm_flags & VM_SHARED)) {
2518
			anon = 1;
2519
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
2520
				ret = VM_FAULT_OOM;
2521
				goto out;
2522
			}
N
Nick Piggin 已提交
2523 2524
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
2525
			if (!page) {
N
Nick Piggin 已提交
2526
				ret = VM_FAULT_OOM;
2527
				goto out;
2528
			}
2529 2530 2531 2532 2533 2534
			if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
2535 2536 2537 2538 2539 2540
			/*
			 * 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
2541
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
2542
			__SetPageUptodate(page);
2543
		} else {
2544 2545
			/*
			 * If the page will be shareable, see if the backing
2546
			 * address space wants to know that the page is about
2547 2548
			 * to become writable
			 */
2549 2550 2551
			if (vma->vm_ops->page_mkwrite) {
				unlock_page(page);
				if (vma->vm_ops->page_mkwrite(vma, page) < 0) {
N
Nick Piggin 已提交
2552 2553
					ret = VM_FAULT_SIGBUS;
					anon = 1; /* no anon but release vmf.page */
2554 2555 2556
					goto out_unlocked;
				}
				lock_page(page);
N
Nick Piggin 已提交
2557 2558 2559 2560 2561 2562 2563 2564
				/*
				 * XXX: this is not quite right (racy vs
				 * invalidate) to unlock and relock the page
				 * like this, however a better fix requires
				 * reworking page_mkwrite locking API, which
				 * is better done later.
				 */
				if (!page->mapping) {
N
Nick Piggin 已提交
2565
					ret = 0;
N
Nick Piggin 已提交
2566 2567 2568
					anon = 1; /* no anon but release vmf.page */
					goto out;
				}
2569
				page_mkwrite = 1;
2570 2571
			}
		}
2572

L
Linus Torvalds 已提交
2573 2574
	}

2575
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
	 * Note that if write_access is true, we either now have
	 * 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... */
2588
	if (likely(pte_same(*page_table, orig_pte))) {
2589 2590
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
2591
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
2592 2593
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
2594
			inc_mm_counter(mm, anon_rss);
R
Rik van Riel 已提交
2595
			SetPageSwapBacked(page);
2596 2597
			lru_cache_add_active_or_unevictable(page, vma);
			page_add_new_anon_rmap(page, vma, address);
2598
		} else {
2599
			inc_mm_counter(mm, file_rss);
2600
			page_add_file_rmap(page);
2601
			if (flags & FAULT_FLAG_WRITE) {
2602
				dirty_page = page;
2603 2604
				get_page(dirty_page);
			}
2605
		}
2606 2607
//TODO:  is this safe?  do_anonymous_page() does it this way.
		set_pte_at(mm, address, page_table, entry);
2608 2609 2610

		/* no need to invalidate: a not-present page won't be cached */
		update_mmu_cache(vma, address, entry);
L
Linus Torvalds 已提交
2611
	} else {
2612 2613
		if (charged)
			mem_cgroup_uncharge_page(page);
2614 2615 2616
		if (anon)
			page_cache_release(page);
		else
2617
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
2618 2619
	}

2620
	pte_unmap_unlock(page_table, ptl);
2621 2622

out:
N
Nick Piggin 已提交
2623
	unlock_page(vmf.page);
2624
out_unlocked:
2625
	if (anon)
N
Nick Piggin 已提交
2626
		page_cache_release(vmf.page);
2627
	else if (dirty_page) {
2628 2629 2630
		if (vma->vm_file)
			file_update_time(vma->vm_file);

2631
		set_page_dirty_balance(dirty_page, page_mkwrite);
2632 2633
		put_page(dirty_page);
	}
2634

N
Nick Piggin 已提交
2635
	return ret;
2636
}
2637

2638 2639 2640 2641 2642
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2643
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2644 2645
	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);

2646 2647
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2648 2649
}

L
Linus Torvalds 已提交
2650 2651 2652 2653
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
2654 2655 2656 2657
 *
 * 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
2658
 */
N
Nick Piggin 已提交
2659
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2660 2661
		unsigned long address, pte_t *page_table, pmd_t *pmd,
		int write_access, pte_t orig_pte)
L
Linus Torvalds 已提交
2662
{
N
Nick Piggin 已提交
2663 2664
	unsigned int flags = FAULT_FLAG_NONLINEAR |
				(write_access ? FAULT_FLAG_WRITE : 0);
2665
	pgoff_t pgoff;
L
Linus Torvalds 已提交
2666

H
Hugh Dickins 已提交
2667
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
2668
		return 0;
L
Linus Torvalds 已提交
2669

N
Nick Piggin 已提交
2670 2671
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||
			!(vma->vm_flags & VM_CAN_NONLINEAR))) {
2672 2673 2674
		/*
		 * Page table corrupted: show pte and kill process.
		 */
N
Nick Piggin 已提交
2675
		print_bad_pte(vma, orig_pte, address);
2676 2677 2678 2679
		return VM_FAULT_OOM;
	}

	pgoff = pte_to_pgoff(orig_pte);
2680
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691
}

/*
 * 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
2692 2693 2694
 * 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
2695 2696
 */
static inline int handle_pte_fault(struct mm_struct *mm,
2697 2698
		struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pmd_t *pmd, int write_access)
L
Linus Torvalds 已提交
2699 2700
{
	pte_t entry;
2701
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2702

2703
	entry = *pte;
L
Linus Torvalds 已提交
2704
	if (!pte_present(entry)) {
2705
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
2706
			if (vma->vm_ops) {
N
Nick Piggin 已提交
2707
				if (likely(vma->vm_ops->fault))
2708 2709
					return do_linear_fault(mm, vma, address,
						pte, pmd, write_access, entry);
J
Jes Sorensen 已提交
2710 2711 2712
			}
			return do_anonymous_page(mm, vma, address,
						 pte, pmd, write_access);
2713
		}
L
Linus Torvalds 已提交
2714
		if (pte_file(entry))
N
Nick Piggin 已提交
2715
			return do_nonlinear_fault(mm, vma, address,
2716 2717 2718
					pte, pmd, write_access, entry);
		return do_swap_page(mm, vma, address,
					pte, pmd, write_access, entry);
L
Linus Torvalds 已提交
2719 2720
	}

H
Hugh Dickins 已提交
2721
	ptl = pte_lockptr(mm, pmd);
2722 2723 2724
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
L
Linus Torvalds 已提交
2725 2726
	if (write_access) {
		if (!pte_write(entry))
2727 2728
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
2729 2730 2731
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
2732
	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {
2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743
		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.
		 */
		if (write_access)
			flush_tlb_page(vma, address);
	}
2744 2745
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2746
	return 0;
L
Linus Torvalds 已提交
2747 2748 2749 2750 2751
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
2752
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2753 2754 2755 2756 2757 2758 2759 2760 2761
		unsigned long address, int write_access)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

2762
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
2763

2764 2765
	if (unlikely(is_vm_hugetlb_page(vma)))
		return hugetlb_fault(mm, vma, address, write_access);
L
Linus Torvalds 已提交
2766 2767 2768 2769

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
2770
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2771 2772
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
2773
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2774 2775
	pte = pte_alloc_map(mm, pmd, address);
	if (!pte)
H
Hugh Dickins 已提交
2776
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
2777

H
Hugh Dickins 已提交
2778
	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
L
Linus Torvalds 已提交
2779 2780 2781 2782 2783
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
2784
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2785
 */
2786
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
2787
{
H
Hugh Dickins 已提交
2788 2789
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
2790
		return -ENOMEM;
L
Linus Torvalds 已提交
2791

2792 2793
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2794
	spin_lock(&mm->page_table_lock);
2795
	if (pgd_present(*pgd))		/* Another has populated it */
2796
		pud_free(mm, new);
2797 2798
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
2799
	spin_unlock(&mm->page_table_lock);
2800
	return 0;
L
Linus Torvalds 已提交
2801 2802 2803 2804 2805 2806
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
2807
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
2808
 */
2809
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
2810
{
H
Hugh Dickins 已提交
2811 2812
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
2813
		return -ENOMEM;
L
Linus Torvalds 已提交
2814

2815 2816
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
2817
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
2818
#ifndef __ARCH_HAS_4LEVEL_HACK
2819
	if (pud_present(*pud))		/* Another has populated it */
2820
		pmd_free(mm, new);
2821 2822
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
2823
#else
2824
	if (pgd_present(*pud))		/* Another has populated it */
2825
		pmd_free(mm, new);
2826 2827
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
2828
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
2829
	spin_unlock(&mm->page_table_lock);
2830
	return 0;
2831
}
L
Linus Torvalds 已提交
2832 2833 2834 2835 2836 2837 2838 2839 2840
#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
2841
		return -ENOMEM;
L
Linus Torvalds 已提交
2842
	write = (vma->vm_flags & VM_WRITE) != 0;
2843 2844
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
2845
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
2846 2847
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
2848
	if (ret < 0)
L
Linus Torvalds 已提交
2849
		return ret;
2850
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
2851 2852 2853 2854 2855
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
2856
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
2857 2858 2859 2860 2861 2862

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
2863 2864
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
2865 2866 2867 2868 2869 2870 2871
	/*
	 * 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
2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895
	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 */
2896

2897
#ifdef CONFIG_HAVE_IOREMAP_PROT
2898 2899 2900
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
2901 2902 2903 2904 2905 2906 2907 2908
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
	spinlock_t *ptl;
	resource_size_t phys_addr = 0;
	struct mm_struct *mm = vma->vm_mm;
2909
	int ret = -EINVAL;
2910

2911 2912
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
2913 2914 2915

	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
2916
		goto out;
2917 2918 2919

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
2920
		goto out;
2921 2922 2923

	pmd = pmd_offset(pud, address);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
2924
		goto out;
2925 2926 2927

	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
	if (pmd_huge(*pmd))
2928
		goto out;
2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942

	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (!ptep)
		goto out;

	pte = *ptep;
	if (!pte_present(pte))
		goto unlock;
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
	phys_addr = pte_pfn(pte);
	phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */

	*prot = pgprot_val(pte_pgprot(pte));
2943 2944
	*phys = phys_addr;
	ret = 0;
2945 2946 2947 2948

unlock:
	pte_unmap_unlock(ptep, ptl);
out:
2949
	return ret;
2950 2951 2952 2953 2954 2955 2956 2957 2958 2959
}

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;
	void *maddr;
	int offset = addr & (PAGE_SIZE-1);

2960
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973
		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

2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989
/*
 * 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
2990
	/* ignore errors, just check how much was successfully transferred */
2991 2992 2993
	while (len) {
		int bytes, ret, offset;
		void *maddr;
2994
		struct page *page = NULL;
2995 2996 2997

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013
		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;
3014
		} else {
3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030
			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);
3031 3032 3033 3034 3035 3036 3037 3038 3039 3040
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);
	mmput(mm);

	return buf - old_buf;
}
3041 3042 3043 3044 3045 3046 3047 3048 3049

/*
 * 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;

3050 3051 3052 3053 3054 3055 3056
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3057 3058 3059 3060 3061 3062 3063 3064
	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;

3065
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078
			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);
}
3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093

#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
	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