memory.c 115.9 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

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

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

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

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

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

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#include "internal.h"

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#ifdef LAST_NID_NOT_IN_PAGE_FLAGS
#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_nid.
#endif

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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

/*
 * 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(high_memory);

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

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

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void sync_mm_rss(struct mm_struct *mm)
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{
	int i;

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

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

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

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

static void check_sync_rss_stat(struct task_struct *task)
{
}

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#endif /* SPLIT_RSS_COUNTING */

#ifdef HAVE_GENERIC_MMU_GATHER

static int tlb_next_batch(struct mmu_gather *tlb)
{
	struct mmu_gather_batch *batch;

	batch = tlb->active;
	if (batch->next) {
		tlb->active = batch->next;
		return 1;
	}

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	if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
		return 0;

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	batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
	if (!batch)
		return 0;

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	tlb->batch_count++;
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	batch->next = NULL;
	batch->nr   = 0;
	batch->max  = MAX_GATHER_BATCH;

	tlb->active->next = batch;
	tlb->active = batch;

	return 1;
}

/* tlb_gather_mmu
 *	Called to initialize an (on-stack) mmu_gather structure for page-table
 *	tear-down from @mm. The @fullmm argument is used when @mm is without
 *	users and we're going to destroy the full address space (exit/execve).
 */
void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
{
	tlb->mm = mm;

	tlb->fullmm     = fullmm;
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	tlb->need_flush_all = 0;
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	tlb->start	= -1UL;
	tlb->end	= 0;
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	tlb->need_flush = 0;
	tlb->local.next = NULL;
	tlb->local.nr   = 0;
	tlb->local.max  = ARRAY_SIZE(tlb->__pages);
	tlb->active     = &tlb->local;
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	tlb->batch_count = 0;
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#ifdef CONFIG_HAVE_RCU_TABLE_FREE
	tlb->batch = NULL;
#endif
}

void tlb_flush_mmu(struct mmu_gather *tlb)
{
	struct mmu_gather_batch *batch;

	if (!tlb->need_flush)
		return;
	tlb->need_flush = 0;
	tlb_flush(tlb);
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
	tlb_table_flush(tlb);
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#endif

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	for (batch = &tlb->local; batch; batch = batch->next) {
		free_pages_and_swap_cache(batch->pages, batch->nr);
		batch->nr = 0;
	}
	tlb->active = &tlb->local;
}

/* tlb_finish_mmu
 *	Called at the end of the shootdown operation to free up any resources
 *	that were required.
 */
void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
	struct mmu_gather_batch *batch, *next;

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	tlb->start = start;
	tlb->end   = end;
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	tlb_flush_mmu(tlb);

	/* keep the page table cache within bounds */
	check_pgt_cache();

	for (batch = tlb->local.next; batch; batch = next) {
		next = batch->next;
		free_pages((unsigned long)batch, 0);
	}
	tlb->local.next = NULL;
}

/* __tlb_remove_page
 *	Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
 *	handling the additional races in SMP caused by other CPUs caching valid
 *	mappings in their TLBs. Returns the number of free page slots left.
 *	When out of page slots we must call tlb_flush_mmu().
 */
int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
	struct mmu_gather_batch *batch;

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	VM_BUG_ON(!tlb->need_flush);
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	batch = tlb->active;
	batch->pages[batch->nr++] = page;
	if (batch->nr == batch->max) {
		if (!tlb_next_batch(tlb))
			return 0;
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		batch = tlb->active;
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	}
	VM_BUG_ON(batch->nr > batch->max);

	return batch->max - batch->nr;
}

#endif /* HAVE_GENERIC_MMU_GATHER */

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#ifdef CONFIG_HAVE_RCU_TABLE_FREE

/*
 * See the comment near struct mmu_table_batch.
 */

static void tlb_remove_table_smp_sync(void *arg)
{
	/* Simply deliver the interrupt */
}

static void tlb_remove_table_one(void *table)
{
	/*
	 * This isn't an RCU grace period and hence the page-tables cannot be
	 * assumed to be actually RCU-freed.
	 *
	 * It is however sufficient for software page-table walkers that rely on
	 * IRQ disabling. See the comment near struct mmu_table_batch.
	 */
	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
	__tlb_remove_table(table);
}

static void tlb_remove_table_rcu(struct rcu_head *head)
{
	struct mmu_table_batch *batch;
	int i;

	batch = container_of(head, struct mmu_table_batch, rcu);

	for (i = 0; i < batch->nr; i++)
		__tlb_remove_table(batch->tables[i]);

	free_page((unsigned long)batch);
}

void tlb_table_flush(struct mmu_gather *tlb)
{
	struct mmu_table_batch **batch = &tlb->batch;

	if (*batch) {
		call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
		*batch = NULL;
	}
}

void tlb_remove_table(struct mmu_gather *tlb, void *table)
{
	struct mmu_table_batch **batch = &tlb->batch;

	tlb->need_flush = 1;

	/*
	 * When there's less then two users of this mm there cannot be a
	 * concurrent page-table walk.
	 */
	if (atomic_read(&tlb->mm->mm_users) < 2) {
		__tlb_remove_table(table);
		return;
	}

	if (*batch == NULL) {
		*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
		if (*batch == NULL) {
			tlb_remove_table_one(table);
			return;
		}
		(*batch)->nr = 0;
	}
	(*batch)->tables[(*batch)->nr++] = table;
	if ((*batch)->nr == MAX_TABLE_BATCH)
		tlb_table_flush(tlb);
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
		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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	int wait_split_huge_page;
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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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	wait_split_huge_page = 0;
	if (likely(pmd_none(*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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	} else if (unlikely(pmd_trans_splitting(*pmd)))
		wait_split_huge_page = 1;
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	spin_unlock(&mm->page_table_lock);
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	if (new)
		pte_free(mm, new);
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	if (wait_split_huge_page)
		wait_split_huge_page(vma->anon_vma, pmd);
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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 (likely(pmd_none(*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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	} else
		VM_BUG_ON(pmd_trans_splitting(*pmd));
630
	spin_unlock(&init_mm.page_table_lock);
631 632
	if (new)
		pte_free_kernel(&init_mm, new);
633
	return 0;
L
Linus Torvalds 已提交
634 635
}

K
KAMEZAWA Hiroyuki 已提交
636 637 638 639 640 641
static inline void init_rss_vec(int *rss)
{
	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
}

static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
642
{
K
KAMEZAWA Hiroyuki 已提交
643 644
	int i;

645
	if (current->mm == mm)
646
		sync_mm_rss(mm);
K
KAMEZAWA Hiroyuki 已提交
647 648 649
	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
650 651
}

N
Nick Piggin 已提交
652
/*
653 654 655
 * 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.
N
Nick Piggin 已提交
656 657 658
 *
 * The calling function must still handle the error.
 */
659 660
static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
			  pte_t pte, struct page *page)
N
Nick Piggin 已提交
661
{
662 663 664 665 666
	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
	pud_t *pud = pud_offset(pgd, addr);
	pmd_t *pmd = pmd_offset(pud, addr);
	struct address_space *mapping;
	pgoff_t index;
667 668 669 670 671 672 673 674 675 676 677 678 679 680
	static unsigned long resume;
	static unsigned long nr_shown;
	static unsigned long nr_unshown;

	/*
	 * Allow a burst of 60 reports, then keep quiet for that minute;
	 * or allow a steady drip of one report per second.
	 */
	if (nr_shown == 60) {
		if (time_before(jiffies, resume)) {
			nr_unshown++;
			return;
		}
		if (nr_unshown) {
681 682
			printk(KERN_ALERT
				"BUG: Bad page map: %lu messages suppressed\n",
683 684 685 686 687 688 689
				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
690 691 692 693

	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
	index = linear_page_index(vma, addr);

694 695
	printk(KERN_ALERT
		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
696 697
		current->comm,
		(long long)pte_val(pte), (long long)pmd_val(*pmd));
698 699
	if (page)
		dump_page(page);
700
	printk(KERN_ALERT
701 702 703 704 705 706
		"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
		(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
	/*
	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
	 */
	if (vma->vm_ops)
J
Joe Perches 已提交
707 708
		printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
		       vma->vm_ops->fault);
709
	if (vma->vm_file && vma->vm_file->f_op)
J
Joe Perches 已提交
710 711
		printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
		       vma->vm_file->f_op->mmap);
N
Nick Piggin 已提交
712
	dump_stack();
713
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
N
Nick Piggin 已提交
714 715
}

716
static inline bool is_cow_mapping(vm_flags_t flags)
717 718 719 720
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

H
Hugh Dickins 已提交
721
/*
N
Nick Piggin 已提交
722
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
723
 *
N
Nick Piggin 已提交
724 725 726
 * "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.
J
Jared Hulbert 已提交
727
 *
N
Nick Piggin 已提交
728 729 730 731 732 733 734 735
 * 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.
736
 *
J
Jared Hulbert 已提交
737 738
 * 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
N
Nick Piggin 已提交
739 740
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
741 742 743
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
744 745 746 747 748 749
 * 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).
J
Jared Hulbert 已提交
750 751
 *
 *
N
Nick Piggin 已提交
752
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
753 754 755 756 757 758 759 760 761
 *
 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 * page" backing, however the difference is that _all_ pages with a struct
 * page (that is, those where pfn_valid is true) are refcounted and considered
 * normal pages by the VM. The disadvantage is that pages are refcounted
 * (which can be slower and simply not an option for some PFNMAP users). The
 * advantage is that we don't have to follow the strict linearity rule of
 * PFNMAP mappings in order to support COWable mappings.
 *
H
Hugh Dickins 已提交
762
 */
N
Nick Piggin 已提交
763 764 765 766 767 768 769
#ifdef __HAVE_ARCH_PTE_SPECIAL
# define HAVE_PTE_SPECIAL 1
#else
# define HAVE_PTE_SPECIAL 0
#endif
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
				pte_t pte)
H
Hugh Dickins 已提交
770
{
771
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
772 773

	if (HAVE_PTE_SPECIAL) {
774 775
		if (likely(!pte_special(pte)))
			goto check_pfn;
H
Hugh Dickins 已提交
776 777
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
778
		if (!is_zero_pfn(pfn))
779
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
780 781 782 783 784
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
785 786 787 788 789 790
	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
N
Nick Piggin 已提交
791 792
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
793 794 795 796 797
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
798 799
	}

H
Hugh Dickins 已提交
800 801
	if (is_zero_pfn(pfn))
		return NULL;
802 803 804 805 806
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
807 808

	/*
N
Nick Piggin 已提交
809 810
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
811
	 */
J
Jared Hulbert 已提交
812
out:
813
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
814 815
}

L
Linus Torvalds 已提交
816 817 818 819 820 821
/*
 * copy one vm_area from one task to the other. Assumes the page tables
 * already present in the new task to be cleared in the whole range
 * covered by this vma.
 */

H
Hugh Dickins 已提交
822
static inline unsigned long
L
Linus Torvalds 已提交
823
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
824
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
825
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
826
{
N
Nick Piggin 已提交
827
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
828 829 830 831 832 833
	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)) {
834 835
			swp_entry_t entry = pte_to_swp_entry(pte);

H
Hugh Dickins 已提交
836 837 838
			if (swap_duplicate(entry) < 0)
				return entry.val;

L
Linus Torvalds 已提交
839 840 841
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
842 843 844
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
845 846
				spin_unlock(&mmlist_lock);
			}
K
KAMEZAWA Hiroyuki 已提交
847 848
			if (likely(!non_swap_entry(entry)))
				rss[MM_SWAPENTS]++;
849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866
			else if (is_migration_entry(entry)) {
				page = migration_entry_to_page(entry);

				if (PageAnon(page))
					rss[MM_ANONPAGES]++;
				else
					rss[MM_FILEPAGES]++;

				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);
				}
867
			}
L
Linus Torvalds 已提交
868
		}
869
		goto out_set_pte;
L
Linus Torvalds 已提交
870 871 872 873 874 875
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
876
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
877
		ptep_set_wrprotect(src_mm, addr, src_pte);
878
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
879 880 881 882 883 884 885 886 887
	}

	/*
	 * 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);
888 889 890 891

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
H
Hugh Dickins 已提交
892
		page_dup_rmap(page);
K
KAMEZAWA Hiroyuki 已提交
893 894 895 896
		if (PageAnon(page))
			rss[MM_ANONPAGES]++;
		else
			rss[MM_FILEPAGES]++;
897
	}
898 899 900

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
901
	return 0;
L
Linus Torvalds 已提交
902 903
}

904 905 906
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)
L
Linus Torvalds 已提交
907
{
908
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
909
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
910
	spinlock_t *src_ptl, *dst_ptl;
911
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
912
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
913
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
914 915

again:
K
KAMEZAWA Hiroyuki 已提交
916 917
	init_rss_vec(rss);

H
Hugh Dickins 已提交
918
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
919 920
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
921
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
922
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
923
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
924 925
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
926
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
927 928 929 930 931 932

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
933 934 935
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
936
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
937 938
				break;
		}
L
Linus Torvalds 已提交
939 940 941 942
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
943 944 945 946
		entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
							vma, addr, rss);
		if (entry.val)
			break;
L
Linus Torvalds 已提交
947 948 949
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

950
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
951
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
952
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
953
	add_mm_rss_vec(dst_mm, rss);
954
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
955
	cond_resched();
H
Hugh Dickins 已提交
956 957 958 959 960 961

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979
	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);
980 981
		if (pmd_trans_huge(*src_pmd)) {
			int err;
982
			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
983 984 985 986 987 988 989 990
			err = copy_huge_pmd(dst_mm, src_mm,
					    dst_pmd, src_pmd, addr, vma);
			if (err == -ENOMEM)
				return -ENOMEM;
			if (!err)
				continue;
			/* fall through */
		}
L
Linus Torvalds 已提交
991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028
		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;
1029 1030 1031
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	bool is_cow;
A
Andrea Arcangeli 已提交
1032
	int ret;
L
Linus Torvalds 已提交
1033

1034 1035 1036 1037 1038 1039
	/*
	 * 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.
	 */
1040 1041
	if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR |
			       VM_PFNMAP | VM_MIXEDMAP))) {
1042 1043 1044 1045
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
1046 1047 1048
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

1049
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1050 1051 1052 1053
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
1054
		ret = track_pfn_copy(vma);
1055 1056 1057 1058
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
1059 1060 1061 1062 1063 1064
	/*
	 * 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.
	 */
1065 1066 1067 1068 1069 1070
	is_cow = is_cow_mapping(vma->vm_flags);
	mmun_start = addr;
	mmun_end   = end;
	if (is_cow)
		mmu_notifier_invalidate_range_start(src_mm, mmun_start,
						    mmun_end);
A
Andrea Arcangeli 已提交
1071 1072

	ret = 0;
L
Linus Torvalds 已提交
1073 1074 1075 1076 1077 1078
	dst_pgd = pgd_offset(dst_mm, addr);
	src_pgd = pgd_offset(src_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(src_pgd))
			continue;
A
Andrea Arcangeli 已提交
1079 1080 1081 1082 1083
		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
1084
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1085

1086 1087
	if (is_cow)
		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
A
Andrea Arcangeli 已提交
1088
	return ret;
L
Linus Torvalds 已提交
1089 1090
}

1091
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1092
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
1093
				unsigned long addr, unsigned long end,
1094
				struct zap_details *details)
L
Linus Torvalds 已提交
1095
{
N
Nick Piggin 已提交
1096
	struct mm_struct *mm = tlb->mm;
P
Peter Zijlstra 已提交
1097
	int force_flush = 0;
K
KAMEZAWA Hiroyuki 已提交
1098
	int rss[NR_MM_COUNTERS];
1099
	spinlock_t *ptl;
1100
	pte_t *start_pte;
1101
	pte_t *pte;
1102
	unsigned long range_start = addr;
K
KAMEZAWA Hiroyuki 已提交
1103

P
Peter Zijlstra 已提交
1104
again:
1105
	init_rss_vec(rss);
1106 1107
	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	pte = start_pte;
1108
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1109 1110
	do {
		pte_t ptent = *pte;
1111
		if (pte_none(ptent)) {
L
Linus Torvalds 已提交
1112
			continue;
1113
		}
1114

L
Linus Torvalds 已提交
1115
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
1116
			struct page *page;
1117

1118
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136
			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
1137
			ptent = ptep_get_and_clear_full(mm, addr, pte,
1138
							tlb->fullmm);
L
Linus Torvalds 已提交
1139 1140 1141 1142 1143 1144
			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
1145
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
1146 1147
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
K
KAMEZAWA Hiroyuki 已提交
1148
				rss[MM_ANONPAGES]--;
1149 1150 1151
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
1152
				if (pte_young(ptent) &&
1153
				    likely(!(vma->vm_flags & VM_SEQ_READ)))
1154
					mark_page_accessed(page);
K
KAMEZAWA Hiroyuki 已提交
1155
				rss[MM_FILEPAGES]--;
1156
			}
1157
			page_remove_rmap(page);
1158 1159
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
P
Peter Zijlstra 已提交
1160 1161 1162
			force_flush = !__tlb_remove_page(tlb, page);
			if (force_flush)
				break;
L
Linus Torvalds 已提交
1163 1164 1165 1166 1167 1168 1169 1170
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
1171 1172 1173
		if (pte_file(ptent)) {
			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
				print_bad_pte(vma, addr, ptent, NULL);
K
KAMEZAWA Hiroyuki 已提交
1174 1175 1176 1177 1178
		} else {
			swp_entry_t entry = pte_to_swp_entry(ptent);

			if (!non_swap_entry(entry))
				rss[MM_SWAPENTS]--;
1179 1180 1181 1182 1183 1184 1185 1186 1187 1188
			else if (is_migration_entry(entry)) {
				struct page *page;

				page = migration_entry_to_page(entry);

				if (PageAnon(page))
					rss[MM_ANONPAGES]--;
				else
					rss[MM_FILEPAGES]--;
			}
K
KAMEZAWA Hiroyuki 已提交
1189 1190 1191
			if (unlikely(!free_swap_and_cache(entry)))
				print_bad_pte(vma, addr, ptent, NULL);
		}
1192
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1193
	} while (pte++, addr += PAGE_SIZE, addr != end);
1194

K
KAMEZAWA Hiroyuki 已提交
1195
	add_mm_rss_vec(mm, rss);
1196
	arch_leave_lazy_mmu_mode();
1197
	pte_unmap_unlock(start_pte, ptl);
1198

P
Peter Zijlstra 已提交
1199 1200 1201 1202 1203 1204 1205
	/*
	 * mmu_gather ran out of room to batch pages, we break out of
	 * the PTE lock to avoid doing the potential expensive TLB invalidate
	 * and page-free while holding it.
	 */
	if (force_flush) {
		force_flush = 0;
1206 1207

#ifdef HAVE_GENERIC_MMU_GATHER
1208 1209
		tlb->start = range_start;
		tlb->end = addr;
1210
#endif
P
Peter Zijlstra 已提交
1211
		tlb_flush_mmu(tlb);
1212 1213
		if (addr != end) {
			range_start = addr;
P
Peter Zijlstra 已提交
1214
			goto again;
1215
		}
P
Peter Zijlstra 已提交
1216 1217
	}

1218
	return addr;
L
Linus Torvalds 已提交
1219 1220
}

1221
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1222
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
1223
				unsigned long addr, unsigned long end,
1224
				struct zap_details *details)
L
Linus Torvalds 已提交
1225 1226 1227 1228 1229 1230 1231
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1232
		if (pmd_trans_huge(*pmd)) {
1233
			if (next - addr != HPAGE_PMD_SIZE) {
1234 1235 1236 1237 1238 1239 1240 1241 1242
#ifdef CONFIG_DEBUG_VM
				if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
					pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
						__func__, addr, end,
						vma->vm_start,
						vma->vm_end);
					BUG();
				}
#endif
1243
				split_huge_page_pmd(vma, addr, pmd);
S
Shaohua Li 已提交
1244
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1245
				goto next;
1246 1247
			/* fall through */
		}
1248 1249 1250 1251 1252 1253 1254 1255 1256
		/*
		 * Here there can be other concurrent MADV_DONTNEED or
		 * trans huge page faults running, and if the pmd is
		 * none or trans huge it can change under us. This is
		 * because MADV_DONTNEED holds the mmap_sem in read
		 * mode.
		 */
		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
			goto next;
1257
		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1258
next:
1259 1260
		cond_resched();
	} while (pmd++, addr = next, addr != end);
1261 1262

	return addr;
L
Linus Torvalds 已提交
1263 1264
}

1265
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1266
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1267
				unsigned long addr, unsigned long end,
1268
				struct zap_details *details)
L
Linus Torvalds 已提交
1269 1270 1271 1272 1273 1274 1275
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1276
		if (pud_none_or_clear_bad(pud))
L
Linus Torvalds 已提交
1277
			continue;
1278 1279
		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
	} while (pud++, addr = next, addr != end);
1280 1281

	return addr;
L
Linus Torvalds 已提交
1282 1283
}

A
Al Viro 已提交
1284 1285 1286 1287
static void unmap_page_range(struct mmu_gather *tlb,
			     struct vm_area_struct *vma,
			     unsigned long addr, unsigned long end,
			     struct zap_details *details)
L
Linus Torvalds 已提交
1288 1289 1290 1291 1292 1293 1294 1295
{
	pgd_t *pgd;
	unsigned long next;

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

	BUG_ON(addr >= end);
1296
	mem_cgroup_uncharge_start();
L
Linus Torvalds 已提交
1297 1298 1299 1300
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
1301
		if (pgd_none_or_clear_bad(pgd))
L
Linus Torvalds 已提交
1302
			continue;
1303 1304
		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
	} while (pgd++, addr = next, addr != end);
L
Linus Torvalds 已提交
1305
	tlb_end_vma(tlb, vma);
1306
	mem_cgroup_uncharge_end();
L
Linus Torvalds 已提交
1307
}
1308

1309 1310 1311

static void unmap_single_vma(struct mmu_gather *tlb,
		struct vm_area_struct *vma, unsigned long start_addr,
1312
		unsigned long end_addr,
1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323
		struct zap_details *details)
{
	unsigned long start = max(vma->vm_start, start_addr);
	unsigned long end;

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

1324 1325 1326
	if (vma->vm_file)
		uprobe_munmap(vma, start, end);

1327
	if (unlikely(vma->vm_flags & VM_PFNMAP))
1328
		untrack_pfn(vma, 0, 0);
1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342

	if (start != end) {
		if (unlikely(is_vm_hugetlb_page(vma))) {
			/*
			 * 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.
			 */
1343 1344
			if (vma->vm_file) {
				mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1345
				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1346 1347
				mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
			}
1348 1349 1350
		} else
			unmap_page_range(tlb, vma, start, end, details);
	}
L
Linus Torvalds 已提交
1351 1352 1353 1354
}

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
1355
 * @tlb: address of the caller's struct mmu_gather
L
Linus Torvalds 已提交
1356 1357 1358 1359
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 *
1360
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1361 1362 1363 1364 1365 1366 1367 1368 1369 1370
 *
 * 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.
 */
A
Al Viro 已提交
1371
void unmap_vmas(struct mmu_gather *tlb,
L
Linus Torvalds 已提交
1372
		struct vm_area_struct *vma, unsigned long start_addr,
1373
		unsigned long end_addr)
L
Linus Torvalds 已提交
1374
{
A
Andrea Arcangeli 已提交
1375
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1376

A
Andrea Arcangeli 已提交
1377
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1378
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1379
		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
A
Andrea Arcangeli 已提交
1380
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1381 1382 1383 1384 1385
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
1386
 * @start: starting address of pages to zap
L
Linus Torvalds 已提交
1387 1388
 * @size: number of bytes to zap
 * @details: details of nonlinear truncation or shared cache invalidation
1389 1390
 *
 * Caller must protect the VMA list
L
Linus Torvalds 已提交
1391
 */
1392
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
L
Linus Torvalds 已提交
1393 1394 1395
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1396
	struct mmu_gather tlb;
1397
	unsigned long end = start + size;
L
Linus Torvalds 已提交
1398 1399

	lru_add_drain();
P
Peter Zijlstra 已提交
1400
	tlb_gather_mmu(&tlb, mm, 0);
1401
	update_hiwater_rss(mm);
1402 1403
	mmu_notifier_invalidate_range_start(mm, start, end);
	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1404
		unmap_single_vma(&tlb, vma, start, end, details);
1405 1406
	mmu_notifier_invalidate_range_end(mm, start, end);
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
1407 1408
}

1409 1410 1411 1412 1413 1414 1415 1416
/**
 * zap_page_range_single - 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
 *
 * The range must fit into one VMA.
L
Linus Torvalds 已提交
1417
 */
1418
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1419 1420 1421
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1422
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1423 1424 1425
	unsigned long end = address + size;

	lru_add_drain();
P
Peter Zijlstra 已提交
1426
	tlb_gather_mmu(&tlb, mm, 0);
1427
	update_hiwater_rss(mm);
1428
	mmu_notifier_invalidate_range_start(mm, address, end);
1429
	unmap_single_vma(&tlb, vma, address, end, details);
1430
	mmu_notifier_invalidate_range_end(mm, address, end);
P
Peter Zijlstra 已提交
1431
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1432 1433
}

1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451
/**
 * 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;
1452
	zap_page_range_single(vma, address, size, NULL);
1453 1454 1455 1456
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

J
Johannes Weiner 已提交
1457
/**
1458
 * follow_page_mask - look up a page descriptor from a user-virtual address
J
Johannes Weiner 已提交
1459 1460 1461
 * @vma: vm_area_struct mapping @address
 * @address: virtual address to look up
 * @flags: flags modifying lookup behaviour
1462
 * @page_mask: on output, *page_mask is set according to the size of the page
J
Johannes Weiner 已提交
1463 1464 1465 1466 1467 1468
 *
 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
 *
 * Returns the mapped (struct page *), %NULL if no mapping exists, or
 * an error pointer if there is a mapping to something not represented
 * by a page descriptor (see also vm_normal_page()).
L
Linus Torvalds 已提交
1469
 */
1470 1471 1472
struct page *follow_page_mask(struct vm_area_struct *vma,
			      unsigned long address, unsigned int flags,
			      unsigned int *page_mask)
L
Linus Torvalds 已提交
1473 1474 1475 1476 1477
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1478
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1479
	struct page *page;
1480
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1481

1482 1483
	*page_mask = 0;

1484 1485 1486 1487 1488
	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
1489

1490
	page = NULL;
L
Linus Torvalds 已提交
1491 1492
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1493
		goto no_page_table;
L
Linus Torvalds 已提交
1494 1495

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1496
	if (pud_none(*pud))
1497
		goto no_page_table;
1498
	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
A
Andi Kleen 已提交
1499 1500 1501 1502 1503 1504 1505
		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
1506
	pmd = pmd_offset(pud, address);
1507
	if (pmd_none(*pmd))
1508
		goto no_page_table;
1509
	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1510 1511
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
L
Linus Torvalds 已提交
1512
		goto out;
1513
	}
1514 1515
	if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
		goto no_page_table;
1516
	if (pmd_trans_huge(*pmd)) {
1517
		if (flags & FOLL_SPLIT) {
1518
			split_huge_page_pmd(vma, address, pmd);
1519 1520
			goto split_fallthrough;
		}
1521 1522 1523 1524 1525 1526
		spin_lock(&mm->page_table_lock);
		if (likely(pmd_trans_huge(*pmd))) {
			if (unlikely(pmd_trans_splitting(*pmd))) {
				spin_unlock(&mm->page_table_lock);
				wait_split_huge_page(vma->anon_vma, pmd);
			} else {
1527
				page = follow_trans_huge_pmd(vma, address,
1528 1529
							     pmd, flags);
				spin_unlock(&mm->page_table_lock);
1530
				*page_mask = HPAGE_PMD_NR - 1;
1531 1532 1533 1534 1535 1536
				goto out;
			}
		} else
			spin_unlock(&mm->page_table_lock);
		/* fall through */
	}
1537
split_fallthrough:
1538 1539 1540
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1541
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1542 1543

	pte = *ptep;
1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561
	if (!pte_present(pte)) {
		swp_entry_t entry;
		/*
		 * KSM's break_ksm() relies upon recognizing a ksm page
		 * even while it is being migrated, so for that case we
		 * need migration_entry_wait().
		 */
		if (likely(!(flags & FOLL_MIGRATION)))
			goto no_page;
		if (pte_none(pte) || pte_file(pte))
			goto no_page;
		entry = pte_to_swp_entry(pte);
		if (!is_migration_entry(entry))
			goto no_page;
		pte_unmap_unlock(ptep, ptl);
		migration_entry_wait(mm, pmd, address);
		goto split_fallthrough;
	}
1562 1563
	if ((flags & FOLL_NUMA) && pte_numa(pte))
		goto no_page;
1564 1565
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
H
Hugh Dickins 已提交
1566

1567
	page = vm_normal_page(vma, address, pte);
H
Hugh Dickins 已提交
1568 1569
	if (unlikely(!page)) {
		if ((flags & FOLL_DUMP) ||
H
Hugh Dickins 已提交
1570
		    !is_zero_pfn(pte_pfn(pte)))
H
Hugh Dickins 已提交
1571 1572 1573
			goto bad_page;
		page = pte_page(pte);
	}
L
Linus Torvalds 已提交
1574

1575
	if (flags & FOLL_GET)
1576
		get_page_foll(page);
1577 1578 1579 1580
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
1581 1582 1583 1584 1585
		/*
		 * pte_mkyoung() would be more correct here, but atomic care
		 * is needed to avoid losing the dirty bit: it is easier to use
		 * mark_page_accessed().
		 */
1586 1587
		mark_page_accessed(page);
	}
1588
	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600
		/*
		 * The preliminary mapping check is mainly to avoid the
		 * pointless overhead of lock_page on the ZERO_PAGE
		 * which might bounce very badly if there is contention.
		 *
		 * If the page is already locked, we don't need to
		 * handle it now - vmscan will handle it later if and
		 * when it attempts to reclaim the page.
		 */
		if (page->mapping && trylock_page(page)) {
			lru_add_drain();  /* push cached pages to LRU */
			/*
1601 1602 1603 1604
			 * Because we lock page here, and migration is
			 * blocked by the pte's page reference, and we
			 * know the page is still mapped, we don't even
			 * need to check for file-cache page truncation.
1605
			 */
1606
			mlock_vma_page(page);
1607 1608 1609
			unlock_page(page);
		}
	}
1610 1611
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1612
out:
1613
	return page;
L
Linus Torvalds 已提交
1614

1615 1616 1617 1618 1619 1620 1621 1622
bad_page:
	pte_unmap_unlock(ptep, ptl);
	return ERR_PTR(-EFAULT);

no_page:
	pte_unmap_unlock(ptep, ptl);
	if (!pte_none(pte))
		return page;
H
Hugh Dickins 已提交
1623

1624 1625 1626
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
H
Hugh Dickins 已提交
1627 1628 1629 1630 1631
	 * has touched so far, we don't want to allocate unnecessary pages or
	 * page tables.  Return error instead of NULL to skip handle_mm_fault,
	 * then get_dump_page() will return NULL to leave a hole in the dump.
	 * But we can only make this optimization where a hole would surely
	 * be zero-filled if handle_mm_fault() actually did handle it.
1632
	 */
H
Hugh Dickins 已提交
1633 1634 1635
	if ((flags & FOLL_DUMP) &&
	    (!vma->vm_ops || !vma->vm_ops->fault))
		return ERR_PTR(-EFAULT);
1636
	return page;
L
Linus Torvalds 已提交
1637 1638
}

1639 1640
static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
{
1641 1642
	return stack_guard_page_start(vma, addr) ||
	       stack_guard_page_end(vma, addr+PAGE_SIZE);
1643 1644
}

H
Huang Ying 已提交
1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693
/**
 * __get_user_pages() - pin user pages in memory
 * @tsk:	task_struct of target task
 * @mm:		mm_struct of target mm
 * @start:	starting user address
 * @nr_pages:	number of pages from start to pin
 * @gup_flags:	flags modifying pin behaviour
 * @pages:	array that receives pointers to the pages pinned.
 *		Should be at least nr_pages long. Or NULL, if caller
 *		only intends to ensure the pages are faulted in.
 * @vmas:	array of pointers to vmas corresponding to each page.
 *		Or NULL if the caller does not require them.
 * @nonblocking: whether waiting for disk IO or mmap_sem contention
 *
 * Returns number of pages pinned. This may be fewer than the number
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
 * were pinned, returns -errno. Each page returned must be released
 * with a put_page() call when it is finished with. vmas will only
 * remain valid while mmap_sem is held.
 *
 * Must be called with mmap_sem held for read or write.
 *
 * __get_user_pages walks a process's page tables and takes a reference to
 * each struct page that each user address corresponds to at a given
 * instant. That is, it takes the page that would be accessed if a user
 * thread accesses the given user virtual address at that instant.
 *
 * This does not guarantee that the page exists in the user mappings when
 * __get_user_pages returns, and there may even be a completely different
 * page there in some cases (eg. if mmapped pagecache has been invalidated
 * and subsequently re faulted). However it does guarantee that the page
 * won't be freed completely. And mostly callers simply care that the page
 * contains data that was valid *at some point in time*. Typically, an IO
 * or similar operation cannot guarantee anything stronger anyway because
 * locks can't be held over the syscall boundary.
 *
 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
 * appropriate) must be called after the page is finished with, and
 * before put_page is called.
 *
 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
 * or mmap_sem contention, and if waiting is needed to pin all pages,
 * *@nonblocking will be set to 0.
 *
 * In most cases, get_user_pages or get_user_pages_fast should be used
 * instead of __get_user_pages. __get_user_pages should be used only if
 * you need some special @gup_flags.
 */
1694 1695 1696 1697
long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long start, unsigned long nr_pages,
		unsigned int gup_flags, struct page **pages,
		struct vm_area_struct **vmas, int *nonblocking)
L
Linus Torvalds 已提交
1698
{
1699
	long i;
H
Hugh Dickins 已提交
1700
	unsigned long vm_flags;
1701
	unsigned int page_mask;
L
Linus Torvalds 已提交
1702

1703
	if (!nr_pages)
1704
		return 0;
H
Hugh Dickins 已提交
1705 1706 1707

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

L
Linus Torvalds 已提交
1708 1709
	/* 
	 * Require read or write permissions.
H
Hugh Dickins 已提交
1710
	 * If FOLL_FORCE is set, we only require the "MAY" flags.
L
Linus Torvalds 已提交
1711
	 */
H
Hugh Dickins 已提交
1712 1713 1714 1715
	vm_flags  = (gup_flags & FOLL_WRITE) ?
			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= (gup_flags & FOLL_FORCE) ?
			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728

	/*
	 * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault
	 * would be called on PROT_NONE ranges. We must never invoke
	 * handle_mm_fault on PROT_NONE ranges or the NUMA hinting
	 * page faults would unprotect the PROT_NONE ranges if
	 * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd
	 * bitflag. So to avoid that, don't set FOLL_NUMA if
	 * FOLL_FORCE is set.
	 */
	if (!(gup_flags & FOLL_FORCE))
		gup_flags |= FOLL_NUMA;

L
Linus Torvalds 已提交
1729 1730 1731
	i = 0;

	do {
1732
		struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1733 1734

		vma = find_extend_vma(mm, start);
1735
		if (!vma && in_gate_area(mm, start)) {
L
Linus Torvalds 已提交
1736 1737 1738 1739 1740
			unsigned long pg = start & PAGE_MASK;
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
N
Nick Piggin 已提交
1741 1742

			/* user gate pages are read-only */
H
Hugh Dickins 已提交
1743
			if (gup_flags & FOLL_WRITE)
L
Linus Torvalds 已提交
1744 1745 1746 1747 1748 1749 1750 1751 1752
				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);
1753 1754
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
1755
			VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1756
			pte = pte_offset_map(pmd, pg);
1757 1758 1759 1760
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
1761
			vma = get_gate_vma(mm);
L
Linus Torvalds 已提交
1762
			if (pages) {
1763 1764
				struct page *page;

1765
				page = vm_normal_page(vma, start, *pte);
1766 1767 1768 1769 1770 1771 1772 1773 1774
				if (!page) {
					if (!(gup_flags & FOLL_DUMP) &&
					     is_zero_pfn(pte_pfn(*pte)))
						page = pte_page(*pte);
					else {
						pte_unmap(pte);
						return i ? : -EFAULT;
					}
				}
1775
				pages[i] = page;
1776
				get_page(page);
L
Linus Torvalds 已提交
1777 1778
			}
			pte_unmap(pte);
1779
			page_mask = 0;
1780
			goto next_page;
L
Linus Torvalds 已提交
1781 1782
		}

N
Nick Piggin 已提交
1783 1784
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
H
Hugh Dickins 已提交
1785
		    !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1786 1787
			return i ? : -EFAULT;

H
Hugh Dickins 已提交
1788 1789
		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
H
Hugh Dickins 已提交
1790
					&start, &nr_pages, i, gup_flags);
H
Hugh Dickins 已提交
1791 1792
			continue;
		}
1793

L
Linus Torvalds 已提交
1794
		do {
1795
			struct page *page;
H
Hugh Dickins 已提交
1796
			unsigned int foll_flags = gup_flags;
1797
			unsigned int page_increm;
L
Linus Torvalds 已提交
1798

1799
			/*
1800
			 * If we have a pending SIGKILL, don't keep faulting
H
Hugh Dickins 已提交
1801
			 * pages and potentially allocating memory.
1802
			 */
H
Hugh Dickins 已提交
1803
			if (unlikely(fatal_signal_pending(current)))
1804
				return i ? i : -ERESTARTSYS;
1805

1806
			cond_resched();
1807 1808
			while (!(page = follow_page_mask(vma, start,
						foll_flags, &page_mask))) {
1809
				int ret;
1810 1811
				unsigned int fault_flags = 0;

1812 1813 1814 1815 1816
				/* For mlock, just skip the stack guard page. */
				if (foll_flags & FOLL_MLOCK) {
					if (stack_guard_page(vma, start))
						goto next_page;
				}
1817 1818 1819 1820
				if (foll_flags & FOLL_WRITE)
					fault_flags |= FAULT_FLAG_WRITE;
				if (nonblocking)
					fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1821 1822
				if (foll_flags & FOLL_NOWAIT)
					fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1823

1824
				ret = handle_mm_fault(mm, vma, start,
1825
							fault_flags);
1826

N
Nick Piggin 已提交
1827 1828 1829
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
1830 1831 1832 1833 1834 1835 1836 1837 1838 1839
					if (ret & (VM_FAULT_HWPOISON |
						   VM_FAULT_HWPOISON_LARGE)) {
						if (i)
							return i;
						else if (gup_flags & FOLL_HWPOISON)
							return -EHWPOISON;
						else
							return -EFAULT;
					}
					if (ret & VM_FAULT_SIGBUS)
N
Nick Piggin 已提交
1840 1841 1842
						return i ? i : -EFAULT;
					BUG();
				}
1843 1844 1845 1846 1847 1848 1849

				if (tsk) {
					if (ret & VM_FAULT_MAJOR)
						tsk->maj_flt++;
					else
						tsk->min_flt++;
				}
N
Nick Piggin 已提交
1850

1851
				if (ret & VM_FAULT_RETRY) {
1852 1853
					if (nonblocking)
						*nonblocking = 0;
1854 1855 1856
					return i;
				}

1857
				/*
N
Nick Piggin 已提交
1858 1859 1860 1861
				 * 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
1862 1863 1864 1865 1866 1867
				 * page lookups as if they were reads. But only
				 * do so when looping for pte_write is futile:
				 * in some cases userspace may also be wanting
				 * to write to the gotten user page, which a
				 * read fault here might prevent (a readonly
				 * page might get reCOWed by userspace write).
1868
				 */
1869 1870
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1871
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1872

1873
				cond_resched();
L
Linus Torvalds 已提交
1874
			}
1875 1876
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1877
			if (pages) {
1878
				pages[i] = page;
1879

1880
				flush_anon_page(vma, page, start);
1881
				flush_dcache_page(page);
1882
				page_mask = 0;
L
Linus Torvalds 已提交
1883
			}
1884
next_page:
1885
			if (vmas) {
L
Linus Torvalds 已提交
1886
				vmas[i] = vma;
1887 1888 1889 1890 1891 1892 1893 1894
				page_mask = 0;
			}
			page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
			if (page_increm > nr_pages)
				page_increm = nr_pages;
			i += page_increm;
			start += page_increm * PAGE_SIZE;
			nr_pages -= page_increm;
1895 1896
		} while (nr_pages && start < vma->vm_end);
	} while (nr_pages);
L
Linus Torvalds 已提交
1897 1898
	return i;
}
H
Huang Ying 已提交
1899
EXPORT_SYMBOL(__get_user_pages);
N
Nick Piggin 已提交
1900

1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957
/*
 * fixup_user_fault() - manually resolve a user page fault
 * @tsk:	the task_struct to use for page fault accounting, or
 *		NULL if faults are not to be recorded.
 * @mm:		mm_struct of target mm
 * @address:	user address
 * @fault_flags:flags to pass down to handle_mm_fault()
 *
 * This is meant to be called in the specific scenario where for locking reasons
 * we try to access user memory in atomic context (within a pagefault_disable()
 * section), this returns -EFAULT, and we want to resolve the user fault before
 * trying again.
 *
 * Typically this is meant to be used by the futex code.
 *
 * The main difference with get_user_pages() is that this function will
 * unconditionally call handle_mm_fault() which will in turn perform all the
 * necessary SW fixup of the dirty and young bits in the PTE, while
 * handle_mm_fault() only guarantees to update these in the struct page.
 *
 * This is important for some architectures where those bits also gate the
 * access permission to the page because they are maintained in software.  On
 * such architectures, gup() will not be enough to make a subsequent access
 * succeed.
 *
 * This should be called with the mm_sem held for read.
 */
int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
		     unsigned long address, unsigned int fault_flags)
{
	struct vm_area_struct *vma;
	int ret;

	vma = find_extend_vma(mm, address);
	if (!vma || address < vma->vm_start)
		return -EFAULT;

	ret = handle_mm_fault(mm, vma, address, fault_flags);
	if (ret & VM_FAULT_ERROR) {
		if (ret & VM_FAULT_OOM)
			return -ENOMEM;
		if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
			return -EHWPOISON;
		if (ret & VM_FAULT_SIGBUS)
			return -EFAULT;
		BUG();
	}
	if (tsk) {
		if (ret & VM_FAULT_MAJOR)
			tsk->maj_flt++;
		else
			tsk->min_flt++;
	}
	return 0;
}

/*
1958
 * get_user_pages() - pin user pages in memory
1959 1960
 * @tsk:	the task_struct to use for page fault accounting, or
 *		NULL if faults are not to be recorded.
1961 1962
 * @mm:		mm_struct of target mm
 * @start:	starting user address
1963
 * @nr_pages:	number of pages from start to pin
1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974
 * @write:	whether pages will be written to by the caller
 * @force:	whether to force write access even if user mapping is
 *		readonly. This will result in the page being COWed even
 *		in MAP_SHARED mappings. You do not want this.
 * @pages:	array that receives pointers to the pages pinned.
 *		Should be at least nr_pages long. Or NULL, if caller
 *		only intends to ensure the pages are faulted in.
 * @vmas:	array of pointers to vmas corresponding to each page.
 *		Or NULL if the caller does not require them.
 *
 * Returns number of pages pinned. This may be fewer than the number
1975
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
 * were pinned, returns -errno. Each page returned must be released
 * with a put_page() call when it is finished with. vmas will only
 * remain valid while mmap_sem is held.
 *
 * Must be called with mmap_sem held for read or write.
 *
 * get_user_pages walks a process's page tables and takes a reference to
 * each struct page that each user address corresponds to at a given
 * instant. That is, it takes the page that would be accessed if a user
 * thread accesses the given user virtual address at that instant.
 *
 * This does not guarantee that the page exists in the user mappings when
 * get_user_pages returns, and there may even be a completely different
 * page there in some cases (eg. if mmapped pagecache has been invalidated
 * and subsequently re faulted). However it does guarantee that the page
 * won't be freed completely. And mostly callers simply care that the page
 * contains data that was valid *at some point in time*. Typically, an IO
 * or similar operation cannot guarantee anything stronger anyway because
 * locks can't be held over the syscall boundary.
 *
 * If write=0, the page must not be written to. If the page is written to,
 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
 * after the page is finished with, and before put_page is called.
 *
 * get_user_pages is typically used for fewer-copy IO operations, to get a
 * handle on the memory by some means other than accesses via the user virtual
 * addresses. The pages may be submitted for DMA to devices or accessed via
 * their kernel linear mapping (via the kmap APIs). Care should be taken to
 * use the correct cache flushing APIs.
 *
 * See also get_user_pages_fast, for performance critical applications.
 */
2008 2009 2010
long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long start, unsigned long nr_pages, int write,
		int force, struct page **pages, struct vm_area_struct **vmas)
N
Nick Piggin 已提交
2011
{
H
Hugh Dickins 已提交
2012
	int flags = FOLL_TOUCH;
N
Nick Piggin 已提交
2013

H
Hugh Dickins 已提交
2014 2015
	if (pages)
		flags |= FOLL_GET;
N
Nick Piggin 已提交
2016
	if (write)
H
Hugh Dickins 已提交
2017
		flags |= FOLL_WRITE;
N
Nick Piggin 已提交
2018
	if (force)
H
Hugh Dickins 已提交
2019
		flags |= FOLL_FORCE;
N
Nick Piggin 已提交
2020

2021 2022
	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
				NULL);
N
Nick Piggin 已提交
2023
}
L
Linus Torvalds 已提交
2024 2025
EXPORT_SYMBOL(get_user_pages);

H
Hugh Dickins 已提交
2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046
/**
 * get_dump_page() - pin user page in memory while writing it to core dump
 * @addr: user address
 *
 * Returns struct page pointer of user page pinned for dump,
 * to be freed afterwards by page_cache_release() or put_page().
 *
 * Returns NULL on any kind of failure - a hole must then be inserted into
 * the corefile, to preserve alignment with its headers; and also returns
 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
 * allowing a hole to be left in the corefile to save diskspace.
 *
 * Called without mmap_sem, but after all other threads have been killed.
 */
#ifdef CONFIG_ELF_CORE
struct page *get_dump_page(unsigned long addr)
{
	struct vm_area_struct *vma;
	struct page *page;

	if (__get_user_pages(current, current->mm, addr, 1,
2047 2048
			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
			     NULL) < 1)
H
Hugh Dickins 已提交
2049 2050 2051 2052 2053 2054
		return NULL;
	flush_cache_page(vma, addr, page_to_pfn(page));
	return page;
}
#endif /* CONFIG_ELF_CORE */

2055
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
2056
			spinlock_t **ptl)
2057 2058 2059 2060
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
2061
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
2062 2063
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
2064
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
2065
		}
2066 2067 2068 2069
	}
	return NULL;
}

2070 2071 2072 2073 2074 2075 2076
/*
 * 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
2077 2078
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
2079
{
N
Nick Piggin 已提交
2080
	struct mm_struct *mm = vma->vm_mm;
2081
	int retval;
2082
	pte_t *pte;
2083 2084
	spinlock_t *ptl;

2085
	retval = -EINVAL;
2086
	if (PageAnon(page))
2087
		goto out;
2088 2089
	retval = -ENOMEM;
	flush_dcache_page(page);
2090
	pte = get_locked_pte(mm, addr, &ptl);
2091
	if (!pte)
2092
		goto out;
2093 2094 2095 2096 2097 2098
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
2099
	inc_mm_counter_fast(mm, MM_FILEPAGES);
2100 2101 2102 2103
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
2104 2105
	pte_unmap_unlock(pte, ptl);
	return retval;
2106 2107 2108 2109 2110 2111
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

2112 2113 2114 2115 2116 2117
/**
 * 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
 *
2118 2119 2120 2121 2122 2123
 * 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
2124
 * (see split_page()).
2125 2126 2127 2128 2129 2130 2131 2132
 *
 * 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.
2133 2134 2135 2136 2137
 *
 * Usually this function is called from f_op->mmap() handler
 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
 * Caller must set VM_MIXEDMAP on vma if it wants to call this
 * function from other places, for example from page-fault handler.
2138
 */
N
Nick Piggin 已提交
2139 2140
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
2141 2142 2143 2144 2145
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
2146 2147 2148 2149 2150
	if (!(vma->vm_flags & VM_MIXEDMAP)) {
		BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
		BUG_ON(vma->vm_flags & VM_PFNMAP);
		vma->vm_flags |= VM_MIXEDMAP;
	}
N
Nick Piggin 已提交
2151
	return insert_page(vma, addr, page, vma->vm_page_prot);
2152
}
2153
EXPORT_SYMBOL(vm_insert_page);
2154

N
Nick Piggin 已提交
2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173
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);
2174
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
2175 2176 2177 2178 2179 2180 2181 2182

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

N
Nick Piggin 已提交
2183 2184 2185 2186 2187 2188
/**
 * 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
 *
2189
 * Similar to vm_insert_page, this allows drivers to insert individual pages
N
Nick Piggin 已提交
2190 2191 2192 2193
 * 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
2194 2195 2196 2197 2198
 *
 * 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
2199 2200
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
2201
			unsigned long pfn)
N
Nick Piggin 已提交
2202
{
2203
	int ret;
2204
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
2205 2206 2207 2208 2209 2210
	/*
	 * 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
2211 2212 2213 2214 2215
	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
2216

N
Nick Piggin 已提交
2217 2218
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
2219
	if (track_pfn_insert(vma, &pgprot, pfn))
2220 2221
		return -EINVAL;

2222
	ret = insert_pfn(vma, addr, pfn, pgprot);
2223 2224

	return ret;
N
Nick Piggin 已提交
2225 2226
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
2227

N
Nick Piggin 已提交
2228 2229 2230 2231
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
2232

N
Nick Piggin 已提交
2233 2234
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
2235

N
Nick Piggin 已提交
2236 2237 2238 2239
	/*
	 * If we don't have pte special, then we have to use the pfn_valid()
	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
	 * refcount the page if pfn_valid is true (hence insert_page rather
H
Hugh Dickins 已提交
2240 2241
	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
	 * without pte special, it would there be refcounted as a normal page.
N
Nick Piggin 已提交
2242 2243 2244 2245 2246 2247 2248 2249
	 */
	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
2250
}
N
Nick Piggin 已提交
2251
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
2252

L
Linus Torvalds 已提交
2253 2254 2255 2256 2257 2258 2259 2260 2261 2262
/*
 * 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
2263
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2264

H
Hugh Dickins 已提交
2265
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
2266 2267
	if (!pte)
		return -ENOMEM;
2268
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
2269 2270
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
2271
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
2272 2273
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
2274
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
2275
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289
	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;
2290
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319
	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;
}

2320 2321 2322 2323 2324 2325 2326 2327 2328 2329
/**
 * 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
2330 2331 2332 2333 2334
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;
2335
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
2336 2337 2338 2339 2340 2341 2342 2343
	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).
2344 2345 2346
	 *   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.
2347 2348 2349 2350
	 *   VM_DONTEXPAND
	 *      Disable vma merging and expanding with mremap().
	 *   VM_DONTDUMP
	 *      Omit vma from core dump, even when VM_IO turned off.
L
Linus Torvalds 已提交
2351 2352 2353 2354
	 *
	 * 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".
2355
	 * See vm_normal_page() for details.
L
Linus Torvalds 已提交
2356
	 */
2357 2358 2359
	if (is_cow_mapping(vma->vm_flags)) {
		if (addr != vma->vm_start || end != vma->vm_end)
			return -EINVAL;
L
Linus Torvalds 已提交
2360
		vma->vm_pgoff = pfn;
2361 2362 2363 2364
	}

	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
	if (err)
2365
		return -EINVAL;
L
Linus Torvalds 已提交
2366

2367
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
L
Linus Torvalds 已提交
2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379

	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);
2380 2381

	if (err)
2382
		untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2383

L
Linus Torvalds 已提交
2384 2385 2386 2387
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434
/**
 * vm_iomap_memory - remap memory to userspace
 * @vma: user vma to map to
 * @start: start of area
 * @len: size of area
 *
 * This is a simplified io_remap_pfn_range() for common driver use. The
 * driver just needs to give us the physical memory range to be mapped,
 * we'll figure out the rest from the vma information.
 *
 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
 * whatever write-combining details or similar.
 */
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
{
	unsigned long vm_len, pfn, pages;

	/* Check that the physical memory area passed in looks valid */
	if (start + len < start)
		return -EINVAL;
	/*
	 * You *really* shouldn't map things that aren't page-aligned,
	 * but we've historically allowed it because IO memory might
	 * just have smaller alignment.
	 */
	len += start & ~PAGE_MASK;
	pfn = start >> PAGE_SHIFT;
	pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
	if (pfn + pages < pfn)
		return -EINVAL;

	/* We start the mapping 'vm_pgoff' pages into the area */
	if (vma->vm_pgoff > pages)
		return -EINVAL;
	pfn += vma->vm_pgoff;
	pages -= vma->vm_pgoff;

	/* Can we fit all of the mapping? */
	vm_len = vma->vm_end - vma->vm_start;
	if (vm_len >> PAGE_SHIFT > pages)
		return -EINVAL;

	/* Ok, let it rip */
	return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_iomap_memory);

2435 2436 2437 2438 2439 2440
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;
2441
	pgtable_t token;
2442
	spinlock_t *uninitialized_var(ptl);
2443 2444 2445 2446 2447 2448 2449 2450 2451

	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));

2452 2453
	arch_enter_lazy_mmu_mode();

2454
	token = pmd_pgtable(*pmd);
2455 2456

	do {
2457
		err = fn(pte++, token, addr, data);
2458 2459
		if (err)
			break;
2460
	} while (addr += PAGE_SIZE, addr != end);
2461

2462 2463
	arch_leave_lazy_mmu_mode();

2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476
	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
2477 2478
	BUG_ON(pud_huge(*pud));

2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519
	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;
2520
	unsigned long end = addr + size;
2521 2522 2523 2524 2525 2526 2527 2528 2529 2530
	int err;

	BUG_ON(addr >= end);
	pgd = pgd_offset(mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
2531

2532 2533 2534 2535
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

2536 2537 2538 2539
/*
 * 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
2540
 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2541 2542
 * must check under lock before unmapping the pte and proceeding
 * (but do_wp_page is only called after already making such a check;
2543
 * and do_anonymous_page can safely check later on).
2544
 */
H
Hugh Dickins 已提交
2545
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2546 2547 2548 2549 2550
				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
2551 2552
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
2553
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
2554
		spin_unlock(ptl);
2555 2556 2557 2558 2559 2560
	}
#endif
	pte_unmap(page_table);
	return same;
}

2561
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2562 2563 2564 2565 2566 2567 2568 2569
{
	/*
	 * 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)) {
2570
		void *kaddr = kmap_atomic(dst);
L
Linus Torvalds 已提交
2571 2572 2573 2574 2575 2576 2577 2578 2579
		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))
2580
			clear_page(kaddr);
2581
		kunmap_atomic(kaddr);
2582
		flush_dcache_page(dst);
N
Nick Piggin 已提交
2583 2584
	} else
		copy_user_highpage(dst, src, va, vma);
2585 2586
}

L
Linus Torvalds 已提交
2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600
/*
 * 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.
 *
2601 2602 2603
 * 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
2604
 */
2605 2606
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2607
		spinlock_t *ptl, pte_t orig_pte)
2608
	__releases(ptl)
L
Linus Torvalds 已提交
2609
{
2610
	struct page *old_page, *new_page = NULL;
L
Linus Torvalds 已提交
2611
	pte_t entry;
2612
	int ret = 0;
2613
	int page_mkwrite = 0;
2614
	struct page *dirty_page = NULL;
2615 2616
	unsigned long mmun_start = 0;	/* For mmu_notifiers */
	unsigned long mmun_end = 0;	/* For mmu_notifiers */
L
Linus Torvalds 已提交
2617

2618
	old_page = vm_normal_page(vma, address, orig_pte);
2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629
	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;
2630
		goto gotten;
2631
	}
L
Linus Torvalds 已提交
2632

2633
	/*
P
Peter Zijlstra 已提交
2634 2635
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2636
	 */
H
Hugh Dickins 已提交
2637
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648
		if (!trylock_page(old_page)) {
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);
			lock_page(old_page);
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				goto unlock;
			}
			page_cache_release(old_page);
P
Peter Zijlstra 已提交
2649
		}
2650
		if (reuse_swap_page(old_page)) {
2651 2652 2653 2654 2655 2656
			/*
			 * The page is all ours.  Move it to our anon_vma so
			 * the rmap code will not search our parent or siblings.
			 * Protected against the rmap code by the page lock.
			 */
			page_move_anon_rmap(old_page, vma, address);
2657 2658 2659
			unlock_page(old_page);
			goto reuse;
		}
2660
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2661
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2662
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
2663 2664 2665 2666 2667
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
2668
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2669 2670 2671 2672 2673 2674 2675 2676 2677
			struct vm_fault vmf;
			int tmp;

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

2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688
			/*
			 * 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);

2689 2690 2691 2692
			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
			if (unlikely(tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
				ret = tmp;
2693
				goto unwritable_page;
2694
			}
N
Nick Piggin 已提交
2695 2696 2697 2698 2699 2700 2701 2702 2703
			if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
				lock_page(old_page);
				if (!old_page->mapping) {
					ret = 0; /* retry the fault */
					unlock_page(old_page);
					goto unwritable_page;
				}
			} else
				VM_BUG_ON(!PageLocked(old_page));
2704 2705 2706 2707 2708 2709 2710 2711 2712

			/*
			 * Since we dropped the lock we need to revalidate
			 * the PTE as someone else may have changed it.  If
			 * they did, we just return, as we can count on the
			 * MMU to tell us if they didn't also make it writable.
			 */
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
N
Nick Piggin 已提交
2713 2714
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
2715
				goto unlock;
N
Nick Piggin 已提交
2716
			}
2717 2718

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2719
		}
2720 2721
		dirty_page = old_page;
		get_page(dirty_page);
2722

2723
reuse:
2724 2725 2726
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2727
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2728
			update_mmu_cache(vma, address, page_table);
2729
		pte_unmap_unlock(page_table, ptl);
2730
		ret |= VM_FAULT_WRITE;
2731 2732 2733 2734 2735 2736 2737 2738 2739 2740

		if (!dirty_page)
			return ret;

		/*
		 * 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.
		 *
2741
		 * __do_fault is protected similarly.
2742 2743 2744 2745
		 */
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
			set_page_dirty_balance(dirty_page, page_mkwrite);
2746 2747 2748
			/* file_update_time outside page_lock */
			if (vma->vm_file)
				file_update_time(vma->vm_file);
2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766
		}
		put_page(dirty_page);
		if (page_mkwrite) {
			struct address_space *mapping = dirty_page->mapping;

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

		return ret;
L
Linus Torvalds 已提交
2767 2768 2769 2770 2771
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2772
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2773
gotten:
2774
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2775 2776

	if (unlikely(anon_vma_prepare(vma)))
2777
		goto oom;
H
Hugh Dickins 已提交
2778

H
Hugh Dickins 已提交
2779
	if (is_zero_pfn(pte_pfn(orig_pte))) {
H
Hugh Dickins 已提交
2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790
		new_page = alloc_zeroed_user_highpage_movable(vma, address);
		if (!new_page)
			goto oom;
	} else {
		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
		if (!new_page)
			goto oom;
		cow_user_page(new_page, old_page, address, vma);
	}
	__SetPageUptodate(new_page);

K
KAMEZAWA Hiroyuki 已提交
2791
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2792 2793
		goto oom_free_new;

2794
	mmun_start  = address & PAGE_MASK;
2795
	mmun_end    = mmun_start + PAGE_SIZE;
2796 2797
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);

L
Linus Torvalds 已提交
2798 2799 2800
	/*
	 * Re-check the pte - we dropped the lock
	 */
2801
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2802
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2803 2804
		if (old_page) {
			if (!PageAnon(old_page)) {
2805 2806
				dec_mm_counter_fast(mm, MM_FILEPAGES);
				inc_mm_counter_fast(mm, MM_ANONPAGES);
H
Hugh Dickins 已提交
2807 2808
			}
		} else
2809
			inc_mm_counter_fast(mm, MM_ANONPAGES);
2810
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2811 2812
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2813 2814 2815 2816 2817 2818
		/*
		 * 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.
		 */
2819
		ptep_clear_flush(vma, address, page_table);
N
Nick Piggin 已提交
2820
		page_add_new_anon_rmap(new_page, vma, address);
2821 2822 2823 2824 2825 2826
		/*
		 * We call the notify macro here because, when using secondary
		 * mmu page tables (such as kvm shadow page tables), we want the
		 * new page to be mapped directly into the secondary page table.
		 */
		set_pte_at_notify(mm, address, page_table, entry);
2827
		update_mmu_cache(vma, address, page_table);
N
Nick Piggin 已提交
2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850
		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.
			 */
2851
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2852 2853
		}

L
Linus Torvalds 已提交
2854 2855
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2856
		ret |= VM_FAULT_WRITE;
2857 2858 2859
	} else
		mem_cgroup_uncharge_page(new_page);

2860 2861
	if (new_page)
		page_cache_release(new_page);
2862
unlock:
2863
	pte_unmap_unlock(page_table, ptl);
2864
	if (mmun_end > mmun_start)
2865
		mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877
	if (old_page) {
		/*
		 * Don't let another task, with possibly unlocked vma,
		 * keep the mlocked page.
		 */
		if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
			lock_page(old_page);	/* LRU manipulation */
			munlock_vma_page(old_page);
			unlock_page(old_page);
		}
		page_cache_release(old_page);
	}
N
Nick Piggin 已提交
2878
	return ret;
2879
oom_free_new:
2880
	page_cache_release(new_page);
2881
oom:
2882
	if (old_page)
H
Hugh Dickins 已提交
2883
		page_cache_release(old_page);
L
Linus Torvalds 已提交
2884
	return VM_FAULT_OOM;
2885 2886 2887

unwritable_page:
	page_cache_release(old_page);
2888
	return ret;
L
Linus Torvalds 已提交
2889 2890
}

2891
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2892 2893 2894
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
2895
	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
L
Linus Torvalds 已提交
2896 2897
}

2898
static inline void unmap_mapping_range_tree(struct rb_root *root,
L
Linus Torvalds 已提交
2899 2900 2901 2902 2903
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	pgoff_t vba, vea, zba, zea;

2904
	vma_interval_tree_foreach(vma, root,
L
Linus Torvalds 已提交
2905 2906 2907
			details->first_index, details->last_index) {

		vba = vma->vm_pgoff;
2908
		vea = vba + vma_pages(vma) - 1;
L
Linus Torvalds 已提交
2909 2910 2911 2912 2913 2914 2915 2916
		/* 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;

2917
		unmap_mapping_range_vma(vma,
L
Linus Torvalds 已提交
2918 2919
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2920
				details);
L
Linus Torvalds 已提交
2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934
	}
}

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.
	 */
2935
	list_for_each_entry(vma, head, shared.nonlinear) {
L
Linus Torvalds 已提交
2936
		details->nonlinear_vma = vma;
2937
		unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
L
Linus Torvalds 已提交
2938 2939 2940 2941
	}
}

/**
2942
 * 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
2943
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2944 2945
 * @holebegin: byte in first page to unmap, relative to the start of
 * the underlying file.  This will be rounded down to a PAGE_SIZE
N
npiggin@suse.de 已提交
2946
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977
 * 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;


2978
	mutex_lock(&mapping->i_mmap_mutex);
2979
	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
L
Linus Torvalds 已提交
2980 2981 2982
		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);
2983
	mutex_unlock(&mapping->i_mmap_mutex);
L
Linus Torvalds 已提交
2984 2985 2986 2987
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
2988 2989 2990
 * 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
2991
 */
2992 2993
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2994
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2995
{
2996
	spinlock_t *ptl;
2997
	struct page *page, *swapcache;
2998
	swp_entry_t entry;
L
Linus Torvalds 已提交
2999
	pte_t pte;
3000
	int locked;
3001
	struct mem_cgroup *ptr;
3002
	int exclusive = 0;
N
Nick Piggin 已提交
3003
	int ret = 0;
L
Linus Torvalds 已提交
3004

H
Hugh Dickins 已提交
3005
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3006
		goto out;
3007 3008

	entry = pte_to_swp_entry(orig_pte);
3009 3010 3011 3012 3013 3014 3015
	if (unlikely(non_swap_entry(entry))) {
		if (is_migration_entry(entry)) {
			migration_entry_wait(mm, pmd, address);
		} else if (is_hwpoison_entry(entry)) {
			ret = VM_FAULT_HWPOISON;
		} else {
			print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
3016
			ret = VM_FAULT_SIGBUS;
3017
		}
3018 3019
		goto out;
	}
3020
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
3021 3022
	page = lookup_swap_cache(entry);
	if (!page) {
3023 3024
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
3025 3026
		if (!page) {
			/*
3027 3028
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
3029
			 */
3030
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
3031 3032
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
3033
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3034
			goto unlock;
L
Linus Torvalds 已提交
3035 3036 3037 3038
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
3039
		count_vm_event(PGMAJFAULT);
3040
		mem_cgroup_count_vm_event(mm, PGMAJFAULT);
3041
	} else if (PageHWPoison(page)) {
3042 3043 3044 3045
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
3046 3047
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3048
		swapcache = page;
3049
		goto out_release;
L
Linus Torvalds 已提交
3050 3051
	}

3052
	swapcache = page;
3053
	locked = lock_page_or_retry(page, mm, flags);
R
Rik van Riel 已提交
3054

3055
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3056 3057 3058 3059
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
3060

A
Andrea Arcangeli 已提交
3061
	/*
3062 3063 3064 3065
	 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
	 * release the swapcache from under us.  The page pin, and pte_same
	 * test below, are not enough to exclude that.  Even if it is still
	 * swapcache, we need to check that the page's swap has not changed.
A
Andrea Arcangeli 已提交
3066
	 */
3067
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
3068 3069
		goto out_page;

3070 3071 3072 3073 3074
	page = ksm_might_need_to_copy(page, vma, address);
	if (unlikely(!page)) {
		ret = VM_FAULT_OOM;
		page = swapcache;
		goto out_page;
H
Hugh Dickins 已提交
3075 3076
	}

K
KAMEZAWA Hiroyuki 已提交
3077
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
3078
		ret = VM_FAULT_OOM;
3079
		goto out_page;
3080 3081
	}

L
Linus Torvalds 已提交
3082
	/*
3083
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
3084
	 */
3085
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
3086
	if (unlikely(!pte_same(*page_table, orig_pte)))
3087 3088 3089 3090 3091
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
3092 3093
	}

3094 3095 3096 3097 3098 3099 3100 3101
	/*
	 * The page isn't present yet, go ahead with the fault.
	 *
	 * Be careful about the sequence of operations here.
	 * To get its accounting right, reuse_swap_page() must be called
	 * while the page is counted on swap but not yet in mapcount i.e.
	 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
	 * must be called after the swap_free(), or it will never succeed.
3102 3103 3104 3105
	 * Because delete_from_swap_page() may be called by reuse_swap_page(),
	 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
	 * in page->private. In this case, a record in swap_cgroup  is silently
	 * discarded at swap_free().
3106
	 */
L
Linus Torvalds 已提交
3107

3108
	inc_mm_counter_fast(mm, MM_ANONPAGES);
K
KAMEZAWA Hiroyuki 已提交
3109
	dec_mm_counter_fast(mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
3110
	pte = mk_pte(page, vma->vm_page_prot);
3111
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
3112
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3113
		flags &= ~FAULT_FLAG_WRITE;
3114
		ret |= VM_FAULT_WRITE;
3115
		exclusive = 1;
L
Linus Torvalds 已提交
3116 3117
	}
	flush_icache_page(vma, page);
3118 3119
	if (pte_swp_soft_dirty(orig_pte))
		pte = pte_mksoft_dirty(pte);
L
Linus Torvalds 已提交
3120
	set_pte_at(mm, address, page_table, pte);
3121
	if (page == swapcache)
3122
		do_page_add_anon_rmap(page, vma, address, exclusive);
3123 3124
	else /* ksm created a completely new copy */
		page_add_new_anon_rmap(page, vma, address);
3125 3126
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
3127

3128
	swap_free(entry);
N
Nick Piggin 已提交
3129
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3130
		try_to_free_swap(page);
3131
	unlock_page(page);
3132
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143
		/*
		 * Hold the lock to avoid the swap entry to be reused
		 * until we take the PT lock for the pte_same() check
		 * (to avoid false positives from pte_same). For
		 * further safety release the lock after the swap_free
		 * so that the swap count won't change under a
		 * parallel locked swapcache.
		 */
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
3144

3145
	if (flags & FAULT_FLAG_WRITE) {
3146 3147 3148
		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
3149 3150 3151 3152
		goto out;
	}

	/* No need to invalidate - it was non-present before */
3153
	update_mmu_cache(vma, address, page_table);
3154
unlock:
3155
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
3156 3157
out:
	return ret;
3158
out_nomap:
3159
	mem_cgroup_cancel_charge_swapin(ptr);
3160
	pte_unmap_unlock(page_table, ptl);
3161
out_page:
3162
	unlock_page(page);
3163
out_release:
3164
	page_cache_release(page);
3165
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
3166 3167 3168
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
3169
	return ret;
L
Linus Torvalds 已提交
3170 3171
}

3172
/*
3173 3174
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3175 3176 3177 3178 3179 3180
 * doesn't hit another vma.
 */
static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
{
	address &= PAGE_MASK;
	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3181 3182 3183 3184 3185 3186 3187 3188 3189 3190
		struct vm_area_struct *prev = vma->vm_prev;

		/*
		 * Is there a mapping abutting this one below?
		 *
		 * That's only ok if it's the same stack mapping
		 * that has gotten split..
		 */
		if (prev && prev->vm_end == address)
			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3191

3192
		expand_downwards(vma, address - PAGE_SIZE);
3193
	}
3194 3195 3196 3197 3198 3199 3200 3201 3202
	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
		struct vm_area_struct *next = vma->vm_next;

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

		expand_upwards(vma, address + PAGE_SIZE);
	}
3203 3204 3205
	return 0;
}

L
Linus Torvalds 已提交
3206
/*
3207 3208 3209
 * 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
3210
 */
3211 3212
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3213
		unsigned int flags)
L
Linus Torvalds 已提交
3214
{
3215 3216
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3217 3218
	pte_t entry;

3219 3220 3221 3222
	pte_unmap(page_table);

	/* Check if we need to add a guard page to the stack */
	if (check_stack_guard_page(vma, address) < 0)
3223 3224
		return VM_FAULT_SIGBUS;

3225
	/* Use the zero-page for reads */
H
Hugh Dickins 已提交
3226 3227 3228
	if (!(flags & FAULT_FLAG_WRITE)) {
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
3229
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
3230 3231 3232 3233 3234
		if (!pte_none(*page_table))
			goto unlock;
		goto setpte;
	}

N
Nick Piggin 已提交
3235 3236 3237 3238 3239 3240
	/* Allocate our own private page. */
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
	page = alloc_zeroed_user_highpage_movable(vma, address);
	if (!page)
		goto oom;
3241 3242 3243 3244 3245
	/*
	 * The memory barrier inside __SetPageUptodate makes sure that
	 * preceeding stores to the page contents become visible before
	 * the set_pte_at() write.
	 */
N
Nick Piggin 已提交
3246
	__SetPageUptodate(page);
3247

K
KAMEZAWA Hiroyuki 已提交
3248
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3249 3250
		goto oom_free_page;

N
Nick Piggin 已提交
3251
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
3252 3253
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
3254

N
Nick Piggin 已提交
3255
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3256
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
3257
		goto release;
H
Hugh Dickins 已提交
3258

3259
	inc_mm_counter_fast(mm, MM_ANONPAGES);
N
Nick Piggin 已提交
3260
	page_add_new_anon_rmap(page, vma, address);
H
Hugh Dickins 已提交
3261
setpte:
3262
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
3263 3264

	/* No need to invalidate - it was non-present before */
3265
	update_mmu_cache(vma, address, page_table);
3266
unlock:
3267
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
3268
	return 0;
3269
release:
3270
	mem_cgroup_uncharge_page(page);
3271 3272
	page_cache_release(page);
	goto unlock;
3273
oom_free_page:
3274
	page_cache_release(page);
3275
oom:
L
Linus Torvalds 已提交
3276 3277 3278 3279
	return VM_FAULT_OOM;
}

/*
3280
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
3281
 * tries to share with existing pages, but makes a separate copy if
3282 3283
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
3284 3285 3286 3287
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
3288
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3289
 * but allow concurrent faults), and pte neither mapped nor locked.
3290
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
3291
 */
3292
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3293
		unsigned long address, pmd_t *pmd,
3294
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3295
{
3296
	pte_t *page_table;
3297
	spinlock_t *ptl;
N
Nick Piggin 已提交
3298
	struct page *page;
3299
	struct page *cow_page;
L
Linus Torvalds 已提交
3300 3301
	pte_t entry;
	int anon = 0;
3302
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
3303 3304
	struct vm_fault vmf;
	int ret;
3305
	int page_mkwrite = 0;
3306

3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326
	/*
	 * If we do COW later, allocate page befor taking lock_page()
	 * on the file cache page. This will reduce lock holding time.
	 */
	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {

		if (unlikely(anon_vma_prepare(vma)))
			return VM_FAULT_OOM;

		cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
		if (!cow_page)
			return VM_FAULT_OOM;

		if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) {
			page_cache_release(cow_page);
			return VM_FAULT_OOM;
		}
	} else
		cow_page = NULL;

N
Nick Piggin 已提交
3327 3328 3329 3330
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
3331

N
Nick Piggin 已提交
3332
	ret = vma->vm_ops->fault(vma, &vmf);
3333 3334
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
			    VM_FAULT_RETRY)))
3335
		goto uncharge_out;
L
Linus Torvalds 已提交
3336

3337 3338 3339
	if (unlikely(PageHWPoison(vmf.page))) {
		if (ret & VM_FAULT_LOCKED)
			unlock_page(vmf.page);
3340 3341
		ret = VM_FAULT_HWPOISON;
		goto uncharge_out;
3342 3343
	}

3344
	/*
N
Nick Piggin 已提交
3345
	 * For consistency in subsequent calls, make the faulted page always
3346 3347
	 * locked.
	 */
N
Nick Piggin 已提交
3348
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
3349
		lock_page(vmf.page);
3350
	else
N
Nick Piggin 已提交
3351
		VM_BUG_ON(!PageLocked(vmf.page));
3352

L
Linus Torvalds 已提交
3353 3354 3355
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
3356
	page = vmf.page;
3357
	if (flags & FAULT_FLAG_WRITE) {
3358
		if (!(vma->vm_flags & VM_SHARED)) {
3359
			page = cow_page;
3360
			anon = 1;
N
Nick Piggin 已提交
3361
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
3362
			__SetPageUptodate(page);
3363
		} else {
3364 3365
			/*
			 * If the page will be shareable, see if the backing
3366
			 * address space wants to know that the page is about
3367 3368
			 * to become writable
			 */
3369
			if (vma->vm_ops->page_mkwrite) {
3370 3371
				int tmp;

3372
				unlock_page(page);
N
Nick Piggin 已提交
3373
				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3374 3375 3376 3377
				tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
				if (unlikely(tmp &
					  (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
					ret = tmp;
N
Nick Piggin 已提交
3378
					goto unwritable_page;
N
Nick Piggin 已提交
3379
				}
N
Nick Piggin 已提交
3380 3381 3382 3383 3384 3385 3386 3387 3388
				if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
					lock_page(page);
					if (!page->mapping) {
						ret = 0; /* retry the fault */
						unlock_page(page);
						goto unwritable_page;
					}
				} else
					VM_BUG_ON(!PageLocked(page));
3389
				page_mkwrite = 1;
3390 3391
			}
		}
3392

L
Linus Torvalds 已提交
3393 3394
	}

3395
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
3396 3397 3398 3399 3400 3401

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
3402
	 * Note that if FAULT_FLAG_WRITE is set, we either now have
L
Linus Torvalds 已提交
3403 3404 3405 3406 3407
	 * 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... */
3408
	if (likely(pte_same(*page_table, orig_pte))) {
3409 3410
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
3411
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
3412 3413
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
3414
			inc_mm_counter_fast(mm, MM_ANONPAGES);
3415
			page_add_new_anon_rmap(page, vma, address);
3416
		} else {
3417
			inc_mm_counter_fast(mm, MM_FILEPAGES);
3418
			page_add_file_rmap(page);
3419
			if (flags & FAULT_FLAG_WRITE) {
3420
				dirty_page = page;
3421 3422
				get_page(dirty_page);
			}
3423
		}
3424
		set_pte_at(mm, address, page_table, entry);
3425 3426

		/* no need to invalidate: a not-present page won't be cached */
3427
		update_mmu_cache(vma, address, page_table);
L
Linus Torvalds 已提交
3428
	} else {
3429 3430
		if (cow_page)
			mem_cgroup_uncharge_page(cow_page);
3431 3432 3433
		if (anon)
			page_cache_release(page);
		else
3434
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
3435 3436
	}

3437
	pte_unmap_unlock(page_table, ptl);
3438

N
Nick Piggin 已提交
3439 3440
	if (dirty_page) {
		struct address_space *mapping = page->mapping;
3441
		int dirtied = 0;
3442

N
Nick Piggin 已提交
3443
		if (set_page_dirty(dirty_page))
3444
			dirtied = 1;
N
Nick Piggin 已提交
3445
		unlock_page(dirty_page);
3446
		put_page(dirty_page);
3447
		if ((dirtied || page_mkwrite) && mapping) {
N
Nick Piggin 已提交
3448 3449 3450 3451 3452 3453 3454 3455
			/*
			 * Some device drivers do not set page.mapping but still
			 * dirty their pages
			 */
			balance_dirty_pages_ratelimited(mapping);
		}

		/* file_update_time outside page_lock */
3456
		if (vma->vm_file && !page_mkwrite)
N
Nick Piggin 已提交
3457 3458 3459 3460 3461
			file_update_time(vma->vm_file);
	} else {
		unlock_page(vmf.page);
		if (anon)
			page_cache_release(vmf.page);
3462
	}
3463

N
Nick Piggin 已提交
3464
	return ret;
N
Nick Piggin 已提交
3465 3466 3467 3468

unwritable_page:
	page_cache_release(page);
	return ret;
3469 3470 3471 3472 3473 3474 3475
uncharge_out:
	/* fs's fault handler get error */
	if (cow_page) {
		mem_cgroup_uncharge_page(cow_page);
		page_cache_release(cow_page);
	}
	return ret;
3476
}
3477

3478 3479
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3480
		unsigned int flags, pte_t orig_pte)
3481 3482
{
	pgoff_t pgoff = (((address & PAGE_MASK)
3483
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3484

3485 3486
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3487 3488
}

L
Linus Torvalds 已提交
3489 3490 3491 3492
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
3493 3494 3495 3496
 *
 * 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
3497
 */
N
Nick Piggin 已提交
3498
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3499
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3500
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3501
{
3502
	pgoff_t pgoff;
L
Linus Torvalds 已提交
3503

3504 3505
	flags |= FAULT_FLAG_NONLINEAR;

H
Hugh Dickins 已提交
3506
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
3507
		return 0;
L
Linus Torvalds 已提交
3508

3509
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3510 3511 3512
		/*
		 * Page table corrupted: show pte and kill process.
		 */
3513
		print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
3514
		return VM_FAULT_SIGBUS;
3515 3516 3517
	}

	pgoff = pte_to_pgoff(orig_pte);
3518
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
3519 3520
}

3521 3522 3523 3524 3525 3526 3527 3528 3529 3530 3531 3532
int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
				unsigned long addr, int current_nid)
{
	get_page(page);

	count_vm_numa_event(NUMA_HINT_FAULTS);
	if (current_nid == numa_node_id())
		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);

	return mpol_misplaced(page, vma, addr);
}

3533 3534 3535
int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
		   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
{
3536
	struct page *page = NULL;
3537
	spinlock_t *ptl;
3538 3539
	int current_nid = -1;
	int target_nid;
3540
	bool migrated = false;
3541 3542 3543 3544 3545 3546 3547 3548 3549 3550 3551 3552

	/*
	* The "pte" at this point cannot be used safely without
	* validation through pte_unmap_same(). It's of NUMA type but
	* the pfn may be screwed if the read is non atomic.
	*
	* ptep_modify_prot_start is not called as this is clearing
	* the _PAGE_NUMA bit and it is not really expected that there
	* would be concurrent hardware modifications to the PTE.
	*/
	ptl = pte_lockptr(mm, pmd);
	spin_lock(ptl);
3553 3554 3555 3556 3557
	if (unlikely(!pte_same(*ptep, pte))) {
		pte_unmap_unlock(ptep, ptl);
		goto out;
	}

3558 3559 3560 3561 3562 3563 3564 3565 3566 3567
	pte = pte_mknonnuma(pte);
	set_pte_at(mm, addr, ptep, pte);
	update_mmu_cache(vma, addr, ptep);

	page = vm_normal_page(vma, addr, pte);
	if (!page) {
		pte_unmap_unlock(ptep, ptl);
		return 0;
	}

3568
	current_nid = page_to_nid(page);
3569
	target_nid = numa_migrate_prep(page, vma, addr, current_nid);
3570
	pte_unmap_unlock(ptep, ptl);
3571 3572 3573 3574 3575 3576 3577 3578 3579 3580 3581
	if (target_nid == -1) {
		/*
		 * Account for the fault against the current node if it not
		 * being replaced regardless of where the page is located.
		 */
		current_nid = numa_node_id();
		put_page(page);
		goto out;
	}

	/* Migrate to the requested node */
3582 3583
	migrated = migrate_misplaced_page(page, target_nid);
	if (migrated)
3584 3585 3586
		current_nid = target_nid;

out:
3587
	if (current_nid != -1)
3588
		task_numa_fault(current_nid, 1, migrated);
3589 3590 3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602
	return 0;
}

/* NUMA hinting page fault entry point for regular pmds */
#ifdef CONFIG_NUMA_BALANCING
static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
		     unsigned long addr, pmd_t *pmdp)
{
	pmd_t pmd;
	pte_t *pte, *orig_pte;
	unsigned long _addr = addr & PMD_MASK;
	unsigned long offset;
	spinlock_t *ptl;
	bool numa = false;
3603
	int local_nid = numa_node_id();
3604 3605 3606 3607 3608 3609 3610 3611 3612 3613 3614 3615 3616 3617 3618 3619 3620 3621 3622 3623 3624 3625

	spin_lock(&mm->page_table_lock);
	pmd = *pmdp;
	if (pmd_numa(pmd)) {
		set_pmd_at(mm, _addr, pmdp, pmd_mknonnuma(pmd));
		numa = true;
	}
	spin_unlock(&mm->page_table_lock);

	if (!numa)
		return 0;

	/* we're in a page fault so some vma must be in the range */
	BUG_ON(!vma);
	BUG_ON(vma->vm_start >= _addr + PMD_SIZE);
	offset = max(_addr, vma->vm_start) & ~PMD_MASK;
	VM_BUG_ON(offset >= PMD_SIZE);
	orig_pte = pte = pte_offset_map_lock(mm, pmdp, _addr, &ptl);
	pte += offset >> PAGE_SHIFT;
	for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) {
		pte_t pteval = *pte;
		struct page *page;
3626 3627
		int curr_nid = local_nid;
		int target_nid;
3628
		bool migrated;
3629 3630 3631 3632 3633 3634 3635 3636 3637 3638 3639 3640 3641 3642 3643 3644 3645
		if (!pte_present(pteval))
			continue;
		if (!pte_numa(pteval))
			continue;
		if (addr >= vma->vm_end) {
			vma = find_vma(mm, addr);
			/* there's a pte present so there must be a vma */
			BUG_ON(!vma);
			BUG_ON(addr < vma->vm_start);
		}
		if (pte_numa(pteval)) {
			pteval = pte_mknonnuma(pteval);
			set_pte_at(mm, addr, pte, pteval);
		}
		page = vm_normal_page(vma, addr, pteval);
		if (unlikely(!page))
			continue;
3646 3647 3648 3649
		/* only check non-shared pages */
		if (unlikely(page_mapcount(page) != 1))
			continue;

3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660 3661
		/*
		 * Note that the NUMA fault is later accounted to either
		 * the node that is currently running or where the page is
		 * migrated to.
		 */
		curr_nid = local_nid;
		target_nid = numa_migrate_prep(page, vma, addr,
					       page_to_nid(page));
		if (target_nid == -1) {
			put_page(page);
			continue;
		}
3662

3663 3664
		/* Migrate to the requested node */
		pte_unmap_unlock(pte, ptl);
3665 3666
		migrated = migrate_misplaced_page(page, target_nid);
		if (migrated)
3667
			curr_nid = target_nid;
3668
		task_numa_fault(curr_nid, 1, migrated);
3669

3670
		pte = pte_offset_map_lock(mm, pmdp, addr, &ptl);
3671 3672 3673 3674 3675 3676 3677 3678 3679 3680
	}
	pte_unmap_unlock(orig_pte, ptl);

	return 0;
}
#else
static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
		     unsigned long addr, pmd_t *pmdp)
{
	BUG();
A
Andrew Morton 已提交
3681
	return 0;
3682 3683 3684
}
#endif /* CONFIG_NUMA_BALANCING */

L
Linus Torvalds 已提交
3685 3686 3687 3688 3689 3690 3691 3692 3693
/*
 * 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
3694 3695 3696
 * 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
3697
 */
3698 3699 3700
int handle_pte_fault(struct mm_struct *mm,
		     struct vm_area_struct *vma, unsigned long address,
		     pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
3701 3702
{
	pte_t entry;
3703
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3704

3705
	entry = *pte;
L
Linus Torvalds 已提交
3706
	if (!pte_present(entry)) {
3707
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
3708
			if (vma->vm_ops) {
N
Nick Piggin 已提交
3709
				if (likely(vma->vm_ops->fault))
3710
					return do_linear_fault(mm, vma, address,
3711
						pte, pmd, flags, entry);
J
Jes Sorensen 已提交
3712 3713
			}
			return do_anonymous_page(mm, vma, address,
3714
						 pte, pmd, flags);
3715
		}
L
Linus Torvalds 已提交
3716
		if (pte_file(entry))
N
Nick Piggin 已提交
3717
			return do_nonlinear_fault(mm, vma, address,
3718
					pte, pmd, flags, entry);
3719
		return do_swap_page(mm, vma, address,
3720
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
3721 3722
	}

3723 3724 3725
	if (pte_numa(entry))
		return do_numa_page(mm, vma, address, entry, pte, pmd);

H
Hugh Dickins 已提交
3726
	ptl = pte_lockptr(mm, pmd);
3727 3728 3729
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
3730
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3731
		if (!pte_write(entry))
3732 3733
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
3734 3735 3736
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
3737
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3738
		update_mmu_cache(vma, address, pte);
3739 3740 3741 3742 3743 3744 3745
	} 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.
		 */
3746
		if (flags & FAULT_FLAG_WRITE)
3747
			flush_tlb_fix_spurious_fault(vma, address);
3748
	}
3749 3750
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3751
	return 0;
L
Linus Torvalds 已提交
3752 3753 3754 3755 3756
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
3757
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3758
		unsigned long address, unsigned int flags)
L
Linus Torvalds 已提交
3759 3760 3761 3762 3763 3764 3765 3766
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

3767
	count_vm_event(PGFAULT);
3768
	mem_cgroup_count_vm_event(mm, PGFAULT);
L
Linus Torvalds 已提交
3769

3770 3771 3772
	/* do counter updates before entering really critical section. */
	check_sync_rss_stat(current);

3773
	if (unlikely(is_vm_hugetlb_page(vma)))
3774
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3775

3776
retry:
L
Linus Torvalds 已提交
3777 3778 3779
	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3780
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3781 3782
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3783
		return VM_FAULT_OOM;
3784 3785 3786 3787 3788 3789
	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
		if (!vma->vm_ops)
			return do_huge_pmd_anonymous_page(mm, vma, address,
							  pmd, flags);
	} else {
		pmd_t orig_pmd = *pmd;
3790 3791
		int ret;

3792 3793
		barrier();
		if (pmd_trans_huge(orig_pmd)) {
3794 3795
			unsigned int dirty = flags & FAULT_FLAG_WRITE;

3796 3797 3798 3799 3800 3801 3802 3803
			/*
			 * If the pmd is splitting, return and retry the
			 * the fault.  Alternative: wait until the split
			 * is done, and goto retry.
			 */
			if (pmd_trans_splitting(orig_pmd))
				return 0;

3804
			if (pmd_numa(orig_pmd))
3805
				return do_huge_pmd_numa_page(mm, vma, address,
3806 3807
							     orig_pmd, pmd);

3808
			if (dirty && !pmd_write(orig_pmd)) {
3809 3810 3811 3812 3813 3814 3815 3816 3817 3818
				ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
							  orig_pmd);
				/*
				 * If COW results in an oom, the huge pmd will
				 * have been split, so retry the fault on the
				 * pte for a smaller charge.
				 */
				if (unlikely(ret & VM_FAULT_OOM))
					goto retry;
				return ret;
3819 3820 3821
			} else {
				huge_pmd_set_accessed(mm, vma, address, pmd,
						      orig_pmd, dirty);
3822
			}
3823

3824 3825 3826 3827
			return 0;
		}
	}

3828 3829 3830
	if (pmd_numa(*pmd))
		return do_pmd_numa_page(mm, vma, address, pmd);

3831 3832 3833 3834 3835
	/*
	 * Use __pte_alloc instead of pte_alloc_map, because we can't
	 * run pte_offset_map on the pmd, if an huge pmd could
	 * materialize from under us from a different thread.
	 */
3836 3837
	if (unlikely(pmd_none(*pmd)) &&
	    unlikely(__pte_alloc(mm, vma, pmd, address)))
H
Hugh Dickins 已提交
3838
		return VM_FAULT_OOM;
3839 3840 3841 3842 3843 3844 3845 3846 3847 3848
	/* if an huge pmd materialized from under us just retry later */
	if (unlikely(pmd_trans_huge(*pmd)))
		return 0;
	/*
	 * A regular pmd is established and it can't morph into a huge pmd
	 * from under us anymore at this point because we hold the mmap_sem
	 * read mode and khugepaged takes it in write mode. So now it's
	 * safe to run pte_offset_map().
	 */
	pte = pte_offset_map(pmd, address);
L
Linus Torvalds 已提交
3849

3850
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3851 3852 3853 3854 3855
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3856
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3857
 */
3858
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3859
{
H
Hugh Dickins 已提交
3860 3861
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3862
		return -ENOMEM;
L
Linus Torvalds 已提交
3863

3864 3865
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3866
	spin_lock(&mm->page_table_lock);
3867
	if (pgd_present(*pgd))		/* Another has populated it */
3868
		pud_free(mm, new);
3869 3870
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3871
	spin_unlock(&mm->page_table_lock);
3872
	return 0;
L
Linus Torvalds 已提交
3873 3874 3875 3876 3877 3878
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3879
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3880
 */
3881
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3882
{
H
Hugh Dickins 已提交
3883 3884
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3885
		return -ENOMEM;
L
Linus Torvalds 已提交
3886

3887 3888
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3889
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3890
#ifndef __ARCH_HAS_4LEVEL_HACK
3891
	if (pud_present(*pud))		/* Another has populated it */
3892
		pmd_free(mm, new);
3893 3894
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3895
#else
3896
	if (pgd_present(*pud))		/* Another has populated it */
3897
		pmd_free(mm, new);
3898 3899
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3900
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3901
	spin_unlock(&mm->page_table_lock);
3902
	return 0;
3903
}
L
Linus Torvalds 已提交
3904 3905 3906 3907 3908
#endif /* __PAGETABLE_PMD_FOLDED */

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
3909
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
3910 3911 3912 3913 3914 3915

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
3916 3917
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
3918

L
Linus Torvalds 已提交
3919 3920 3921 3922 3923
	return 0;
}
__initcall(gate_vma_init);
#endif

3924
struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
L
Linus Torvalds 已提交
3925 3926 3927 3928 3929 3930 3931 3932
{
#ifdef AT_SYSINFO_EHDR
	return &gate_vma;
#else
	return NULL;
#endif
}

3933
int in_gate_area_no_mm(unsigned long addr)
L
Linus Torvalds 已提交
3934 3935 3936 3937 3938 3939 3940 3941 3942
{
#ifdef AT_SYSINFO_EHDR
	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
		return 1;
#endif
	return 0;
}

#endif	/* __HAVE_ARCH_GATE_AREA */
3943

3944
static int __follow_pte(struct mm_struct *mm, unsigned long address,
J
Johannes Weiner 已提交
3945 3946 3947 3948 3949 3950 3951 3952 3953 3954 3955 3956 3957 3958 3959 3960
		pte_t **ptepp, spinlock_t **ptlp)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep;

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

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

	pmd = pmd_offset(pud, address);
3961
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3962 3963 3964 3965 3966 3967 3968 3969 3970 3971 3972 3973 3974 3975 3976 3977 3978 3979 3980 3981
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
		goto out;

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

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

3982 3983 3984 3985 3986 3987 3988 3989 3990 3991 3992
static inline int follow_pte(struct mm_struct *mm, unsigned long address,
			     pte_t **ptepp, spinlock_t **ptlp)
{
	int res;

	/* (void) is needed to make gcc happy */
	(void) __cond_lock(*ptlp,
			   !(res = __follow_pte(mm, address, ptepp, ptlp)));
	return res;
}

J
Johannes Weiner 已提交
3993 3994 3995 3996 3997 3998 3999 4000 4001 4002 4003 4004 4005 4006 4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017 4018 4019 4020 4021
/**
 * follow_pfn - look up PFN at a user virtual address
 * @vma: memory mapping
 * @address: user virtual address
 * @pfn: location to store found PFN
 *
 * Only IO mappings and raw PFN mappings are allowed.
 *
 * Returns zero and the pfn at @pfn on success, -ve otherwise.
 */
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
	unsigned long *pfn)
{
	int ret = -EINVAL;
	spinlock_t *ptl;
	pte_t *ptep;

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

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

4022
#ifdef CONFIG_HAVE_IOREMAP_PROT
4023 4024 4025
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
4026
{
4027
	int ret = -EINVAL;
4028 4029 4030
	pte_t *ptep, pte;
	spinlock_t *ptl;

4031 4032
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
4033

4034
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4035
		goto out;
4036
	pte = *ptep;
4037

4038 4039 4040 4041
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
4042
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4043

4044
	ret = 0;
4045 4046 4047
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
4048
	return ret;
4049 4050 4051 4052 4053 4054 4055
}

int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
			void *buf, int len, int write)
{
	resource_size_t phys_addr;
	unsigned long prot = 0;
K
KOSAKI Motohiro 已提交
4056
	void __iomem *maddr;
4057 4058
	int offset = addr & (PAGE_SIZE-1);

4059
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
4060 4061 4062 4063 4064 4065 4066 4067 4068 4069 4070 4071 4072
		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

4073
/*
4074 4075
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
4076
 */
4077 4078
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long addr, void *buf, int len, int write)
4079 4080 4081 4082 4083
{
	struct vm_area_struct *vma;
	void *old_buf = buf;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
4084
	/* ignore errors, just check how much was successfully transferred */
4085 4086 4087
	while (len) {
		int bytes, ret, offset;
		void *maddr;
4088
		struct page *page = NULL;
4089 4090 4091

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
4092 4093 4094 4095 4096 4097 4098
		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);
4099
			if (!vma || vma->vm_start > addr)
4100 4101 4102 4103 4104 4105 4106 4107
				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;
4108
		} else {
4109 4110 4111 4112 4113 4114 4115 4116 4117 4118 4119 4120 4121 4122 4123 4124
			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);
4125 4126 4127 4128 4129 4130 4131 4132 4133
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
4134

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Stephen Wilson 已提交
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/**
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 * access_remote_vm - access another process' address space
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Stephen Wilson 已提交
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 * @mm:		the mm_struct of the target address space
 * @addr:	start address to access
 * @buf:	source or destination buffer
 * @len:	number of bytes to transfer
 * @write:	whether the access is a write
 *
 * The caller must hold a reference on @mm.
 */
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
		void *buf, int len, int write)
{
	return __access_remote_vm(NULL, mm, addr, buf, len, write);
}

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/*
 * 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;
	int ret;

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

	ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
	mmput(mm);

	return ret;
}

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/*
 * 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;

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	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

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	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) {
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Andy Shevchenko 已提交
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			char *p;
4194

4195
			p = d_path(&f->f_path, buf, PAGE_SIZE);
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			if (IS_ERR(p))
				p = "?";
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Andy Shevchenko 已提交
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			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
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					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
4204
	up_read(&mm->mmap_sem);
4205
}
4206

4207
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
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void might_fault(void)
{
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	/*
	 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
	 * holding the mmap_sem, this is safe because kernel memory doesn't
	 * get paged out, therefore we'll never actually fault, and the
	 * below annotations will generate false positives.
	 */
	if (segment_eq(get_fs(), KERNEL_DS))
		return;

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	/*
	 * 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.
	 */
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	if (in_atomic())
		return;

	__might_sleep(__FILE__, __LINE__, 0);

	if (current->mm)
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		might_lock_read(&current->mm->mmap_sem);
}
EXPORT_SYMBOL(might_fault);
#endif
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Andrea Arcangeli 已提交
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#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
static void clear_gigantic_page(struct page *page,
				unsigned long addr,
				unsigned int pages_per_huge_page)
{
	int i;
	struct page *p = page;

	might_sleep();
	for (i = 0; i < pages_per_huge_page;
	     i++, p = mem_map_next(p, page, i)) {
		cond_resched();
		clear_user_highpage(p, addr + i * PAGE_SIZE);
	}
}
void clear_huge_page(struct page *page,
		     unsigned long addr, unsigned int pages_per_huge_page)
{
	int i;

	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
		clear_gigantic_page(page, addr, pages_per_huge_page);
		return;
	}

	might_sleep();
	for (i = 0; i < pages_per_huge_page; i++) {
		cond_resched();
		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
	}
}

static void copy_user_gigantic_page(struct page *dst, struct page *src,
				    unsigned long addr,
				    struct vm_area_struct *vma,
				    unsigned int pages_per_huge_page)
{
	int i;
	struct page *dst_base = dst;
	struct page *src_base = src;

	for (i = 0; i < pages_per_huge_page; ) {
		cond_resched();
		copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);

		i++;
		dst = mem_map_next(dst, dst_base, i);
		src = mem_map_next(src, src_base, i);
	}
}

void copy_user_huge_page(struct page *dst, struct page *src,
			 unsigned long addr, struct vm_area_struct *vma,
			 unsigned int pages_per_huge_page)
{
	int i;

	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
		copy_user_gigantic_page(dst, src, addr, vma,
					pages_per_huge_page);
		return;
	}

	might_sleep();
	for (i = 0; i < pages_per_huge_page; i++) {
		cond_resched();
		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
	}
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */