memory.c 99.8 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 <linux/dma-debug.h>
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#include <linux/debugfs.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_CPUPID_NOT_IN_PAGE_FLAGS
#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
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#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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EXPORT_SYMBOL(zero_pfn);

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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).
 */
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void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
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{
	tlb->mm = mm;

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	/* Is it from 0 to ~0? */
	tlb->fullmm     = !(start | (end+1));
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	tlb->need_flush_all = 0;
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	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
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	__tlb_reset_range(tlb);
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}

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static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
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{
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	if (!tlb->end)
		return;

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	tlb_flush(tlb);
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	mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
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#ifdef CONFIG_HAVE_RCU_TABLE_FREE
	tlb_table_flush(tlb);
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#endif
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	__tlb_reset_range(tlb);
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}

static void tlb_flush_mmu_free(struct mmu_gather *tlb)
{
	struct mmu_gather_batch *batch;
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	for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
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		free_pages_and_swap_cache(batch->pages, batch->nr);
		batch->nr = 0;
	}
	tlb->active = &tlb->local;
}

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void tlb_flush_mmu(struct mmu_gather *tlb)
{
	tlb_flush_mmu_tlbonly(tlb);
	tlb_flush_mmu_free(tlb);
}

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/* 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;

	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->end);
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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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	}
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	VM_BUG_ON_PAGE(batch->nr > batch->max, page);
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	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;

	/*
	 * 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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/*
 * 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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	atomic_long_dec(&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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 */
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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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	spinlock_t *ptl;
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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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	ptl = pmd_lock(mm, pmd);
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	wait_split_huge_page = 0;
	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
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		atomic_long_inc(&mm->nr_ptes);
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		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(ptl);
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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));
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	spin_unlock(&init_mm.page_table_lock);
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	if (new)
		pte_free_kernel(&init_mm, new);
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	return 0;
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}

K
KAMEZAWA Hiroyuki 已提交
622 623 624 625 626 627
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)
628
{
K
KAMEZAWA Hiroyuki 已提交
629 630
	int i;

631
	if (current->mm == mm)
632
		sync_mm_rss(mm);
K
KAMEZAWA Hiroyuki 已提交
633 634 635
	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
636 637
}

N
Nick Piggin 已提交
638
/*
639 640 641
 * 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
642 643 644
 *
 * The calling function must still handle the error.
 */
645 646
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
647
{
648 649 650 651 652
	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;
653 654 655 656 657 658 659 660 661 662 663 664 665 666
	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) {
667 668
			printk(KERN_ALERT
				"BUG: Bad page map: %lu messages suppressed\n",
669 670 671 672 673 674 675
				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
676 677 678 679

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

680 681
	printk(KERN_ALERT
		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
682 683
		current->comm,
		(long long)pte_val(pte), (long long)pmd_val(*pmd));
684
	if (page)
685
		dump_page(page, "bad pte");
686
	printk(KERN_ALERT
687 688 689 690 691 692
		"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
693 694
		printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
		       vma->vm_ops->fault);
A
Al Viro 已提交
695
	if (vma->vm_file)
J
Joe Perches 已提交
696 697
		printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
		       vma->vm_file->f_op->mmap);
N
Nick Piggin 已提交
698
	dump_stack();
699
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
N
Nick Piggin 已提交
700 701
}

H
Hugh Dickins 已提交
702
/*
N
Nick Piggin 已提交
703
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
704
 *
N
Nick Piggin 已提交
705 706 707
 * "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
708
 *
N
Nick Piggin 已提交
709 710 711 712 713 714 715 716
 * 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.
717
 *
J
Jared Hulbert 已提交
718 719
 * 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
720 721
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
722 723 724
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
725 726 727 728 729 730
 * 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
731 732
 *
 *
N
Nick Piggin 已提交
733
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
734 735 736 737 738 739 740 741 742
 *
 * 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
743
 */
N
Nick Piggin 已提交
744 745 746 747 748 749 750
#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
751
{
752
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
753 754

	if (HAVE_PTE_SPECIAL) {
755
		if (likely(!pte_special(pte)))
756
			goto check_pfn;
H
Hugh Dickins 已提交
757 758
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
759
		if (!is_zero_pfn(pfn))
760
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
761 762 763 764 765
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
766 767 768 769 770 771
	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
772 773
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
774 775 776 777 778
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
779 780
	}

781 782
	if (is_zero_pfn(pfn))
		return NULL;
783 784 785 786 787
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
788 789

	/*
N
Nick Piggin 已提交
790 791
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
792
	 */
J
Jared Hulbert 已提交
793
out:
794
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
795 796
}

L
Linus Torvalds 已提交
797 798 799 800 801 802
/*
 * 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
803
static inline unsigned long
L
Linus Torvalds 已提交
804
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
805
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
806
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
807
{
N
Nick Piggin 已提交
808
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
809 810 811 812 813 814
	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)) {
815 816
			swp_entry_t entry = pte_to_swp_entry(pte);

817 818 819 820 821 822 823 824 825 826 827 828
			if (likely(!non_swap_entry(entry))) {
				if (swap_duplicate(entry) < 0)
					return entry.val;

				/* make sure dst_mm is on swapoff's mmlist. */
				if (unlikely(list_empty(&dst_mm->mmlist))) {
					spin_lock(&mmlist_lock);
					if (list_empty(&dst_mm->mmlist))
						list_add(&dst_mm->mmlist,
							 &src_mm->mmlist);
					spin_unlock(&mmlist_lock);
				}
K
KAMEZAWA Hiroyuki 已提交
829
				rss[MM_SWAPENTS]++;
830
			} else if (is_migration_entry(entry)) {
831 832 833 834 835 836 837 838 839 840 841 842 843 844 845
				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);
846 847
					if (pte_swp_soft_dirty(*src_pte))
						pte = pte_swp_mksoft_dirty(pte);
848 849
					set_pte_at(src_mm, addr, src_pte, pte);
				}
850
			}
L
Linus Torvalds 已提交
851
		}
852
		goto out_set_pte;
L
Linus Torvalds 已提交
853 854 855 856 857 858
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
859
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
860
		ptep_set_wrprotect(src_mm, addr, src_pte);
861
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
862 863 864 865 866 867 868 869 870
	}

	/*
	 * 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);
871 872 873 874

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
H
Hugh Dickins 已提交
875
		page_dup_rmap(page);
K
KAMEZAWA Hiroyuki 已提交
876 877 878 879
		if (PageAnon(page))
			rss[MM_ANONPAGES]++;
		else
			rss[MM_FILEPAGES]++;
880
	}
881 882 883

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
884
	return 0;
L
Linus Torvalds 已提交
885 886
}

887
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
888 889
		   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
890
{
891
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
892
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
893
	spinlock_t *src_ptl, *dst_ptl;
894
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
895
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
896
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
897 898

again:
K
KAMEZAWA Hiroyuki 已提交
899 900
	init_rss_vec(rss);

H
Hugh Dickins 已提交
901
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
902 903
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
904
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
905
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
906
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
907 908
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
909
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
910 911 912 913 914 915

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
916 917 918
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
919
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
920 921
				break;
		}
L
Linus Torvalds 已提交
922 923 924 925
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
926 927 928 929
		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
930 931 932
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

933
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
934
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
935
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
936
	add_mm_rss_vec(dst_mm, rss);
937
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
938
	cond_resched();
H
Hugh Dickins 已提交
939 940 941 942 943 944

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962
	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);
963 964
		if (pmd_trans_huge(*src_pmd)) {
			int err;
965
			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
966 967 968 969 970 971 972 973
			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
974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011
		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;
1012 1013 1014
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	bool is_cow;
A
Andrea Arcangeli 已提交
1015
	int ret;
L
Linus Torvalds 已提交
1016

1017 1018 1019 1020 1021 1022
	/*
	 * 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.
	 */
1023 1024
	if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR |
			       VM_PFNMAP | VM_MIXEDMAP))) {
1025 1026 1027 1028
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
1029 1030 1031
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

1032
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1033 1034 1035 1036
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
1037
		ret = track_pfn_copy(vma);
1038 1039 1040 1041
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
1042 1043 1044 1045 1046 1047
	/*
	 * 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.
	 */
1048 1049 1050 1051 1052 1053
	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
1054 1055

	ret = 0;
L
Linus Torvalds 已提交
1056 1057 1058 1059 1060 1061
	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
1062 1063 1064 1065 1066
		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
1067
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1068

1069 1070
	if (is_cow)
		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
A
Andrea Arcangeli 已提交
1071
	return ret;
L
Linus Torvalds 已提交
1072 1073
}

1074
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1075
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
1076
				unsigned long addr, unsigned long end,
1077
				struct zap_details *details)
L
Linus Torvalds 已提交
1078
{
N
Nick Piggin 已提交
1079
	struct mm_struct *mm = tlb->mm;
P
Peter Zijlstra 已提交
1080
	int force_flush = 0;
K
KAMEZAWA Hiroyuki 已提交
1081
	int rss[NR_MM_COUNTERS];
1082
	spinlock_t *ptl;
1083
	pte_t *start_pte;
1084
	pte_t *pte;
1085
	swp_entry_t entry;
K
KAMEZAWA Hiroyuki 已提交
1086

P
Peter Zijlstra 已提交
1087
again:
1088
	init_rss_vec(rss);
1089 1090
	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	pte = start_pte;
1091
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1092 1093
	do {
		pte_t ptent = *pte;
1094
		if (pte_none(ptent)) {
L
Linus Torvalds 已提交
1095
			continue;
1096
		}
1097

L
Linus Torvalds 已提交
1098
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
1099
			struct page *page;
1100

1101
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
1102 1103 1104 1105 1106 1107 1108 1109 1110 1111
			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;
			}
N
Nick Piggin 已提交
1112
			ptent = ptep_get_and_clear_full(mm, addr, pte,
1113
							tlb->fullmm);
L
Linus Torvalds 已提交
1114 1115 1116 1117
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (PageAnon(page))
K
KAMEZAWA Hiroyuki 已提交
1118
				rss[MM_ANONPAGES]--;
1119
			else {
1120 1121
				if (pte_dirty(ptent)) {
					force_flush = 1;
1122
					set_page_dirty(page);
1123
				}
1124
				if (pte_young(ptent) &&
1125
				    likely(!(vma->vm_flags & VM_SEQ_READ)))
1126
					mark_page_accessed(page);
K
KAMEZAWA Hiroyuki 已提交
1127
				rss[MM_FILEPAGES]--;
1128
			}
1129
			page_remove_rmap(page);
1130 1131
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
1132 1133
			if (unlikely(!__tlb_remove_page(tlb, page))) {
				force_flush = 1;
1134
				addr += PAGE_SIZE;
P
Peter Zijlstra 已提交
1135
				break;
1136
			}
L
Linus Torvalds 已提交
1137 1138
			continue;
		}
1139
		/* If details->check_mapping, we leave swap entries. */
L
Linus Torvalds 已提交
1140 1141
		if (unlikely(details))
			continue;
K
KAMEZAWA Hiroyuki 已提交
1142

1143 1144 1145 1146 1147
		entry = pte_to_swp_entry(ptent);
		if (!non_swap_entry(entry))
			rss[MM_SWAPENTS]--;
		else if (is_migration_entry(entry)) {
			struct page *page;
1148

1149
			page = migration_entry_to_page(entry);
1150

1151 1152 1153 1154
			if (PageAnon(page))
				rss[MM_ANONPAGES]--;
			else
				rss[MM_FILEPAGES]--;
K
KAMEZAWA Hiroyuki 已提交
1155
		}
1156 1157
		if (unlikely(!free_swap_and_cache(entry)))
			print_bad_pte(vma, addr, ptent, NULL);
1158
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1159
	} while (pte++, addr += PAGE_SIZE, addr != end);
1160

K
KAMEZAWA Hiroyuki 已提交
1161
	add_mm_rss_vec(mm, rss);
1162
	arch_leave_lazy_mmu_mode();
1163

1164
	/* Do the actual TLB flush before dropping ptl */
1165
	if (force_flush)
1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177
		tlb_flush_mmu_tlbonly(tlb);
	pte_unmap_unlock(start_pte, ptl);

	/*
	 * If we forced a TLB flush (either due to running out of
	 * batch buffers or because we needed to flush dirty TLB
	 * entries before releasing the ptl), free the batched
	 * memory too. Restart if we didn't do everything.
	 */
	if (force_flush) {
		force_flush = 0;
		tlb_flush_mmu_free(tlb);
1178 1179

		if (addr != end)
P
Peter Zijlstra 已提交
1180 1181 1182
			goto again;
	}

1183
	return addr;
L
Linus Torvalds 已提交
1184 1185
}

1186
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1187
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
1188
				unsigned long addr, unsigned long end,
1189
				struct zap_details *details)
L
Linus Torvalds 已提交
1190 1191 1192 1193 1194 1195 1196
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1197
		if (pmd_trans_huge(*pmd)) {
1198
			if (next - addr != HPAGE_PMD_SIZE) {
1199 1200 1201 1202 1203 1204 1205 1206 1207
#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
1208
				split_huge_page_pmd(vma, addr, pmd);
S
Shaohua Li 已提交
1209
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1210
				goto next;
1211 1212
			/* fall through */
		}
1213 1214 1215 1216 1217 1218 1219 1220 1221
		/*
		 * 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;
1222
		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1223
next:
1224 1225
		cond_resched();
	} while (pmd++, addr = next, addr != end);
1226 1227

	return addr;
L
Linus Torvalds 已提交
1228 1229
}

1230
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1231
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1232
				unsigned long addr, unsigned long end,
1233
				struct zap_details *details)
L
Linus Torvalds 已提交
1234 1235 1236 1237 1238 1239 1240
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1241
		if (pud_none_or_clear_bad(pud))
L
Linus Torvalds 已提交
1242
			continue;
1243 1244
		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
	} while (pud++, addr = next, addr != end);
1245 1246

	return addr;
L
Linus Torvalds 已提交
1247 1248
}

A
Al Viro 已提交
1249 1250 1251 1252
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
1253 1254 1255 1256
{
	pgd_t *pgd;
	unsigned long next;

1257
	if (details && !details->check_mapping)
L
Linus Torvalds 已提交
1258 1259 1260 1261 1262 1263 1264
		details = NULL;

	BUG_ON(addr >= end);
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
1265
		if (pgd_none_or_clear_bad(pgd))
L
Linus Torvalds 已提交
1266
			continue;
1267 1268
		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
	} while (pgd++, addr = next, addr != end);
L
Linus Torvalds 已提交
1269 1270
	tlb_end_vma(tlb, vma);
}
1271

1272 1273 1274

static void unmap_single_vma(struct mmu_gather *tlb,
		struct vm_area_struct *vma, unsigned long start_addr,
1275
		unsigned long end_addr,
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286
		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;

1287 1288 1289
	if (vma->vm_file)
		uprobe_munmap(vma, start, end);

1290
	if (unlikely(vma->vm_flags & VM_PFNMAP))
1291
		untrack_pfn(vma, 0, 0);
1292 1293 1294 1295 1296 1297 1298

	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
1299
			 * cleanup path of mmap_region. When
1300
			 * hugetlbfs ->mmap method fails,
1301
			 * mmap_region() nullifies vma->vm_file
1302 1303 1304 1305
			 * before calling this function to clean up.
			 * Since no pte has actually been setup, it is
			 * safe to do nothing in this case.
			 */
1306
			if (vma->vm_file) {
1307
				i_mmap_lock_write(vma->vm_file->f_mapping);
1308
				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1309
				i_mmap_unlock_write(vma->vm_file->f_mapping);
1310
			}
1311 1312 1313
		} else
			unmap_page_range(tlb, vma, start, end, details);
	}
L
Linus Torvalds 已提交
1314 1315 1316 1317
}

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
1318
 * @tlb: address of the caller's struct mmu_gather
L
Linus Torvalds 已提交
1319 1320 1321 1322
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 *
1323
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1324 1325 1326 1327 1328 1329 1330 1331 1332 1333
 *
 * 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
1334
void unmap_vmas(struct mmu_gather *tlb,
L
Linus Torvalds 已提交
1335
		struct vm_area_struct *vma, unsigned long start_addr,
1336
		unsigned long end_addr)
L
Linus Torvalds 已提交
1337
{
A
Andrea Arcangeli 已提交
1338
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1339

A
Andrea Arcangeli 已提交
1340
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1341
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1342
		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
A
Andrea Arcangeli 已提交
1343
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1344 1345 1346 1347 1348
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
1349
 * @start: starting address of pages to zap
L
Linus Torvalds 已提交
1350
 * @size: number of bytes to zap
1351
 * @details: details of shared cache invalidation
1352 1353
 *
 * Caller must protect the VMA list
L
Linus Torvalds 已提交
1354
 */
1355
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
L
Linus Torvalds 已提交
1356 1357 1358
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1359
	struct mmu_gather tlb;
1360
	unsigned long end = start + size;
L
Linus Torvalds 已提交
1361 1362

	lru_add_drain();
1363
	tlb_gather_mmu(&tlb, mm, start, end);
1364
	update_hiwater_rss(mm);
1365 1366
	mmu_notifier_invalidate_range_start(mm, start, end);
	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1367
		unmap_single_vma(&tlb, vma, start, end, details);
1368 1369
	mmu_notifier_invalidate_range_end(mm, start, end);
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
1370 1371
}

1372 1373 1374 1375 1376
/**
 * 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
1377
 * @details: details of shared cache invalidation
1378 1379
 *
 * The range must fit into one VMA.
L
Linus Torvalds 已提交
1380
 */
1381
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1382 1383 1384
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1385
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1386 1387 1388
	unsigned long end = address + size;

	lru_add_drain();
1389
	tlb_gather_mmu(&tlb, mm, address, end);
1390
	update_hiwater_rss(mm);
1391
	mmu_notifier_invalidate_range_start(mm, address, end);
1392
	unmap_single_vma(&tlb, vma, address, end, details);
1393
	mmu_notifier_invalidate_range_end(mm, address, end);
P
Peter Zijlstra 已提交
1394
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1395 1396
}

1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414
/**
 * 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;
1415
	zap_page_range_single(vma, address, size, NULL);
1416 1417 1418 1419
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

1420
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
1421
			spinlock_t **ptl)
1422 1423 1424 1425
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1426
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1427 1428
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
1429
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1430
		}
1431 1432 1433 1434
	}
	return NULL;
}

1435 1436 1437 1438 1439 1440 1441
/*
 * 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
1442 1443
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1444
{
N
Nick Piggin 已提交
1445
	struct mm_struct *mm = vma->vm_mm;
1446
	int retval;
1447
	pte_t *pte;
1448 1449
	spinlock_t *ptl;

1450
	retval = -EINVAL;
1451
	if (PageAnon(page))
1452
		goto out;
1453 1454
	retval = -ENOMEM;
	flush_dcache_page(page);
1455
	pte = get_locked_pte(mm, addr, &ptl);
1456
	if (!pte)
1457
		goto out;
1458 1459 1460 1461 1462 1463
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
1464
	inc_mm_counter_fast(mm, MM_FILEPAGES);
1465 1466 1467 1468
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1469 1470
	pte_unmap_unlock(pte, ptl);
	return retval;
1471 1472 1473 1474 1475 1476
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1477 1478 1479 1480 1481 1482
/**
 * 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
 *
1483 1484 1485 1486 1487 1488
 * 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
1489
 * (see split_page()).
1490 1491 1492 1493 1494 1495 1496 1497
 *
 * 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.
1498 1499 1500 1501 1502
 *
 * 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.
1503
 */
N
Nick Piggin 已提交
1504 1505
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1506 1507 1508 1509 1510
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1511 1512 1513 1514 1515
	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
1516
	return insert_page(vma, addr, page, vma->vm_page_prot);
1517
}
1518
EXPORT_SYMBOL(vm_insert_page);
1519

N
Nick Piggin 已提交
1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538
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);
1539
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1540 1541 1542 1543 1544 1545 1546 1547

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

N
Nick Piggin 已提交
1548 1549 1550 1551 1552 1553
/**
 * 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
 *
1554
 * Similar to vm_insert_page, this allows drivers to insert individual pages
N
Nick Piggin 已提交
1555 1556 1557 1558
 * 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
1559 1560 1561 1562 1563
 *
 * 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
1564 1565
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1566
			unsigned long pfn)
N
Nick Piggin 已提交
1567
{
1568
	int ret;
1569
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1570 1571 1572 1573 1574 1575
	/*
	 * 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
1576 1577 1578 1579 1580
	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
1581

N
Nick Piggin 已提交
1582 1583
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1584
	if (track_pfn_insert(vma, &pgprot, pfn))
1585 1586
		return -EINVAL;

1587
	ret = insert_pfn(vma, addr, pfn, pgprot);
1588 1589

	return ret;
N
Nick Piggin 已提交
1590 1591
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1592

N
Nick Piggin 已提交
1593 1594 1595 1596
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
1597

N
Nick Piggin 已提交
1598 1599
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1600

N
Nick Piggin 已提交
1601 1602 1603 1604
	/*
	 * 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
1605 1606
	 * 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
1607 1608 1609 1610 1611 1612 1613 1614
	 */
	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
1615
}
N
Nick Piggin 已提交
1616
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1617

L
Linus Torvalds 已提交
1618 1619 1620 1621 1622 1623 1624 1625 1626 1627
/*
 * 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
1628
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1629

H
Hugh Dickins 已提交
1630
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1631 1632
	if (!pte)
		return -ENOMEM;
1633
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1634 1635
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1636
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1637 1638
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1639
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1640
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654
	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;
1655
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
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
	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;
}

1685 1686 1687 1688 1689 1690 1691 1692 1693 1694
/**
 * 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
1695 1696 1697 1698 1699
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;
1700
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1701 1702 1703 1704 1705 1706 1707 1708
	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).
1709 1710 1711
	 *   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.
1712 1713 1714 1715
	 *   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
1716 1717 1718 1719
	 *
	 * 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".
1720
	 * See vm_normal_page() for details.
L
Linus Torvalds 已提交
1721
	 */
1722 1723 1724
	if (is_cow_mapping(vma->vm_flags)) {
		if (addr != vma->vm_start || end != vma->vm_end)
			return -EINVAL;
L
Linus Torvalds 已提交
1725
		vma->vm_pgoff = pfn;
1726 1727 1728 1729
	}

	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
	if (err)
1730
		return -EINVAL;
L
Linus Torvalds 已提交
1731

1732
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
L
Linus Torvalds 已提交
1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744

	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);
1745 1746

	if (err)
1747
		untrack_pfn(vma, pfn, PAGE_ALIGN(size));
1748

L
Linus Torvalds 已提交
1749 1750 1751 1752
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799
/**
 * 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);

1800 1801 1802 1803 1804 1805
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;
1806
	pgtable_t token;
1807
	spinlock_t *uninitialized_var(ptl);
1808 1809 1810 1811 1812 1813 1814 1815 1816

	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));

1817 1818
	arch_enter_lazy_mmu_mode();

1819
	token = pmd_pgtable(*pmd);
1820 1821

	do {
1822
		err = fn(pte++, token, addr, data);
1823 1824
		if (err)
			break;
1825
	} while (addr += PAGE_SIZE, addr != end);
1826

1827 1828
	arch_leave_lazy_mmu_mode();

1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841
	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
1842 1843
	BUG_ON(pud_huge(*pud));

1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884
	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;
1885
	unsigned long end = addr + size;
1886 1887 1888 1889 1890 1891 1892 1893 1894 1895
	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);
1896

1897 1898 1899 1900
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1901
/*
1902 1903 1904 1905 1906
 * handle_pte_fault chooses page fault handler according to an entry which was
 * read non-atomically.  Before making any commitment, on those architectures
 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
 * parts, do_swap_page must check under lock before unmapping the pte and
 * proceeding (but do_wp_page is only called after already making such a check;
1907
 * and do_anonymous_page can safely check later on).
1908
 */
H
Hugh Dickins 已提交
1909
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1910 1911 1912 1913 1914
				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
1915 1916
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1917
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1918
		spin_unlock(ptl);
1919 1920 1921 1922 1923 1924
	}
#endif
	pte_unmap(page_table);
	return same;
}

1925
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1926
{
1927 1928
	debug_dma_assert_idle(src);

1929 1930 1931 1932 1933 1934 1935
	/*
	 * 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)) {
1936
		void *kaddr = kmap_atomic(dst);
L
Linus Torvalds 已提交
1937 1938 1939 1940 1941 1942 1943 1944 1945
		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))
1946
			clear_page(kaddr);
1947
		kunmap_atomic(kaddr);
1948
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1949 1950
	} else
		copy_user_highpage(dst, src, va, vma);
1951 1952
}

1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984
/*
 * 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.
 */
static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
	       unsigned long address)
{
	struct vm_fault vmf;
	int ret;

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

	ret = vma->vm_ops->page_mkwrite(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
		return ret;
	if (unlikely(!(ret & VM_FAULT_LOCKED))) {
		lock_page(page);
		if (!page->mapping) {
			unlock_page(page);
			return 0; /* retry */
		}
		ret |= VM_FAULT_LOCKED;
	} else
		VM_BUG_ON_PAGE(!PageLocked(page), page);
	return ret;
}

L
Linus Torvalds 已提交
1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998
/*
 * This routine handles present pages, when users try to write
 * to a shared page. It is done by copying the page to a new address
 * and decrementing the shared-page counter for the old page.
 *
 * Note that this routine assumes that the protection checks have been
 * done by the caller (the low-level page fault routine in most cases).
 * Thus we can safely just mark it writable once we've done any necessary
 * COW.
 *
 * We also mark the page dirty at this point even though the page will
 * change only once the write actually happens. This avoids a few races,
 * and potentially makes it more efficient.
 *
1999 2000 2001
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), with pte both mapped and locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2002
 */
2003 2004
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2005
		spinlock_t *ptl, pte_t orig_pte)
2006
	__releases(ptl)
L
Linus Torvalds 已提交
2007
{
2008
	struct page *old_page, *new_page = NULL;
L
Linus Torvalds 已提交
2009
	pte_t entry;
2010
	int ret = 0;
2011
	int page_mkwrite = 0;
2012
	struct page *dirty_page = NULL;
2013 2014
	unsigned long mmun_start = 0;	/* For mmu_notifiers */
	unsigned long mmun_end = 0;	/* For mmu_notifiers */
2015
	struct mem_cgroup *memcg;
L
Linus Torvalds 已提交
2016

2017
	old_page = vm_normal_page(vma, address, orig_pte);
2018 2019
	if (!old_page) {
		/*
2020 2021
		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
		 * VM_PFNMAP VMA.
2022 2023 2024 2025 2026 2027 2028 2029
		 *
		 * 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;
2030
		goto gotten;
2031
	}
L
Linus Torvalds 已提交
2032

2033
	/*
P
Peter Zijlstra 已提交
2034 2035
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2036
	 */
H
Hugh Dickins 已提交
2037
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048
		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
2049
		}
2050
		if (reuse_swap_page(old_page)) {
2051 2052 2053 2054 2055 2056
			/*
			 * 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);
2057 2058 2059
			unlock_page(old_page);
			goto reuse;
		}
2060
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2061
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2062
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
2063 2064 2065 2066 2067
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
2068
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2069
			int tmp;
2070 2071
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);
2072 2073 2074 2075 2076
			tmp = do_page_mkwrite(vma, old_page, address);
			if (unlikely(!tmp || (tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
				page_cache_release(old_page);
				return tmp;
2077
			}
2078 2079 2080 2081 2082 2083 2084 2085
			/*
			 * 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
2086 2087
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
2088
				goto unlock;
N
Nick Piggin 已提交
2089
			}
2090 2091

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2092
		}
2093 2094
		dirty_page = old_page;
		get_page(dirty_page);
2095

2096
reuse:
2097 2098 2099 2100 2101 2102 2103 2104
		/*
		 * Clear the pages cpupid information as the existing
		 * information potentially belongs to a now completely
		 * unrelated process.
		 */
		if (old_page)
			page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1);

2105 2106 2107
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2108
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2109
			update_mmu_cache(vma, address, page_table);
2110
		pte_unmap_unlock(page_table, ptl);
2111
		ret |= VM_FAULT_WRITE;
2112 2113 2114 2115 2116

		if (!dirty_page)
			return ret;

		if (!page_mkwrite) {
2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133
			struct address_space *mapping;
			int dirtied;

			lock_page(dirty_page);
			dirtied = set_page_dirty(dirty_page);
			VM_BUG_ON_PAGE(PageAnon(dirty_page), dirty_page);
			mapping = dirty_page->mapping;
			unlock_page(dirty_page);

			if (dirtied && mapping) {
				/*
				 * Some device drivers do not set page.mapping
				 * but still dirty their pages
				 */
				balance_dirty_pages_ratelimited(mapping);
			}

2134 2135 2136
			/* file_update_time outside page_lock */
			if (vma->vm_file)
				file_update_time(vma->vm_file);
2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154
		}
		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
2155 2156 2157 2158 2159
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2160
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2161
gotten:
2162
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2163 2164

	if (unlikely(anon_vma_prepare(vma)))
2165
		goto oom;
H
Hugh Dickins 已提交
2166

H
Hugh Dickins 已提交
2167
	if (is_zero_pfn(pte_pfn(orig_pte))) {
H
Hugh Dickins 已提交
2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178
		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);

2179
	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg))
2180 2181
		goto oom_free_new;

2182
	mmun_start  = address & PAGE_MASK;
2183
	mmun_end    = mmun_start + PAGE_SIZE;
2184 2185
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);

L
Linus Torvalds 已提交
2186 2187 2188
	/*
	 * Re-check the pte - we dropped the lock
	 */
2189
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2190
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2191 2192
		if (old_page) {
			if (!PageAnon(old_page)) {
2193 2194
				dec_mm_counter_fast(mm, MM_FILEPAGES);
				inc_mm_counter_fast(mm, MM_ANONPAGES);
H
Hugh Dickins 已提交
2195 2196
			}
		} else
2197
			inc_mm_counter_fast(mm, MM_ANONPAGES);
2198
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2199 2200
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2201 2202 2203 2204 2205 2206
		/*
		 * 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.
		 */
2207
		ptep_clear_flush_notify(vma, address, page_table);
N
Nick Piggin 已提交
2208
		page_add_new_anon_rmap(new_page, vma, address);
2209 2210
		mem_cgroup_commit_charge(new_page, memcg, false);
		lru_cache_add_active_or_unevictable(new_page, vma);
2211 2212 2213 2214 2215 2216
		/*
		 * 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);
2217
		update_mmu_cache(vma, address, page_table);
N
Nick Piggin 已提交
2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240
		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.
			 */
2241
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2242 2243
		}

L
Linus Torvalds 已提交
2244 2245
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2246
		ret |= VM_FAULT_WRITE;
2247
	} else
2248
		mem_cgroup_cancel_charge(new_page, memcg);
2249

2250 2251
	if (new_page)
		page_cache_release(new_page);
2252
unlock:
2253
	pte_unmap_unlock(page_table, ptl);
2254
	if (mmun_end > mmun_start)
2255
		mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267
	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
2268
	return ret;
2269
oom_free_new:
2270
	page_cache_release(new_page);
2271
oom:
2272
	if (old_page)
H
Hugh Dickins 已提交
2273
		page_cache_release(old_page);
L
Linus Torvalds 已提交
2274 2275 2276
	return VM_FAULT_OOM;
}

2277
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2278 2279 2280
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
2281
	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
L
Linus Torvalds 已提交
2282 2283
}

2284
static inline void unmap_mapping_range_tree(struct rb_root *root,
L
Linus Torvalds 已提交
2285 2286 2287 2288 2289
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	pgoff_t vba, vea, zba, zea;

2290
	vma_interval_tree_foreach(vma, root,
L
Linus Torvalds 已提交
2291 2292 2293
			details->first_index, details->last_index) {

		vba = vma->vm_pgoff;
2294
		vea = vba + vma_pages(vma) - 1;
L
Linus Torvalds 已提交
2295 2296 2297 2298 2299 2300 2301 2302
		/* 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;

2303
		unmap_mapping_range_vma(vma,
L
Linus Torvalds 已提交
2304 2305
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2306
				details);
L
Linus Torvalds 已提交
2307 2308 2309 2310
	}
}

/**
2311 2312 2313 2314
 * 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
2315
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2316 2317
 * @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
2318
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348
 * 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.first_index = hba;
	details.last_index = hba + hlen - 1;
	if (details.last_index < details.first_index)
		details.last_index = ULONG_MAX;


2349
	i_mmap_lock_write(mapping);
2350
	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
L
Linus Torvalds 已提交
2351
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
2352
	i_mmap_unlock_write(mapping);
L
Linus Torvalds 已提交
2353 2354 2355 2356
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
2357 2358
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
2359 2360 2361 2362
 * We return with pte unmapped and unlocked.
 *
 * We return with the mmap_sem locked or unlocked in the same cases
 * as does filemap_fault().
L
Linus Torvalds 已提交
2363
 */
2364 2365
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2366
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2367
{
2368
	spinlock_t *ptl;
2369
	struct page *page, *swapcache;
2370
	struct mem_cgroup *memcg;
2371
	swp_entry_t entry;
L
Linus Torvalds 已提交
2372
	pte_t pte;
2373
	int locked;
2374
	int exclusive = 0;
N
Nick Piggin 已提交
2375
	int ret = 0;
L
Linus Torvalds 已提交
2376

H
Hugh Dickins 已提交
2377
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2378
		goto out;
2379 2380

	entry = pte_to_swp_entry(orig_pte);
2381 2382 2383 2384 2385 2386 2387
	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
2388
			ret = VM_FAULT_SIGBUS;
2389
		}
2390 2391
		goto out;
	}
2392
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2393 2394
	page = lookup_swap_cache(entry);
	if (!page) {
2395 2396
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2397 2398
		if (!page) {
			/*
2399 2400
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2401
			 */
2402
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2403 2404
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2405
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2406
			goto unlock;
L
Linus Torvalds 已提交
2407 2408 2409 2410
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2411
		count_vm_event(PGMAJFAULT);
2412
		mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2413
	} else if (PageHWPoison(page)) {
2414 2415 2416 2417
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2418 2419
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2420
		swapcache = page;
2421
		goto out_release;
L
Linus Torvalds 已提交
2422 2423
	}

2424
	swapcache = page;
2425
	locked = lock_page_or_retry(page, mm, flags);
R
Rik van Riel 已提交
2426

2427
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2428 2429 2430 2431
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2432

A
Andrea Arcangeli 已提交
2433
	/*
2434 2435 2436 2437
	 * 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
2438
	 */
2439
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2440 2441
		goto out_page;

2442 2443 2444 2445 2446
	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
2447 2448
	}

2449
	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg)) {
2450
		ret = VM_FAULT_OOM;
2451
		goto out_page;
2452 2453
	}

L
Linus Torvalds 已提交
2454
	/*
2455
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2456
	 */
2457
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2458
	if (unlikely(!pte_same(*page_table, orig_pte)))
2459 2460 2461 2462 2463
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2464 2465
	}

2466 2467 2468 2469 2470 2471 2472 2473 2474
	/*
	 * 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.
	 */
L
Linus Torvalds 已提交
2475

2476
	inc_mm_counter_fast(mm, MM_ANONPAGES);
K
KAMEZAWA Hiroyuki 已提交
2477
	dec_mm_counter_fast(mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
2478
	pte = mk_pte(page, vma->vm_page_prot);
2479
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2480
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2481
		flags &= ~FAULT_FLAG_WRITE;
2482
		ret |= VM_FAULT_WRITE;
2483
		exclusive = 1;
L
Linus Torvalds 已提交
2484 2485
	}
	flush_icache_page(vma, page);
2486 2487
	if (pte_swp_soft_dirty(orig_pte))
		pte = pte_mksoft_dirty(pte);
L
Linus Torvalds 已提交
2488
	set_pte_at(mm, address, page_table, pte);
2489
	if (page == swapcache) {
2490
		do_page_add_anon_rmap(page, vma, address, exclusive);
2491 2492
		mem_cgroup_commit_charge(page, memcg, true);
	} else { /* ksm created a completely new copy */
2493
		page_add_new_anon_rmap(page, vma, address);
2494 2495 2496
		mem_cgroup_commit_charge(page, memcg, false);
		lru_cache_add_active_or_unevictable(page, vma);
	}
L
Linus Torvalds 已提交
2497

2498
	swap_free(entry);
N
Nick Piggin 已提交
2499
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2500
		try_to_free_swap(page);
2501
	unlock_page(page);
2502
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513
		/*
		 * 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);
	}
2514

2515
	if (flags & FAULT_FLAG_WRITE) {
2516 2517 2518
		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
2519 2520 2521 2522
		goto out;
	}

	/* No need to invalidate - it was non-present before */
2523
	update_mmu_cache(vma, address, page_table);
2524
unlock:
2525
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2526 2527
out:
	return ret;
2528
out_nomap:
2529
	mem_cgroup_cancel_charge(page, memcg);
2530
	pte_unmap_unlock(page_table, ptl);
2531
out_page:
2532
	unlock_page(page);
2533
out_release:
2534
	page_cache_release(page);
2535
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2536 2537 2538
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
2539
	return ret;
L
Linus Torvalds 已提交
2540 2541
}

2542
/*
2543 2544
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2545 2546 2547 2548 2549 2550
 * 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) {
2551 2552 2553 2554 2555 2556 2557 2558 2559 2560
		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;
2561

2562
		return expand_downwards(vma, address - PAGE_SIZE);
2563
	}
2564 2565 2566 2567 2568 2569 2570
	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;

2571
		return expand_upwards(vma, address + PAGE_SIZE);
2572
	}
2573 2574 2575
	return 0;
}

L
Linus Torvalds 已提交
2576
/*
2577 2578 2579
 * 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
2580
 */
2581 2582
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2583
		unsigned int flags)
L
Linus Torvalds 已提交
2584
{
2585
	struct mem_cgroup *memcg;
2586 2587
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2588 2589
	pte_t entry;

2590 2591 2592 2593
	pte_unmap(page_table);

	/* Check if we need to add a guard page to the stack */
	if (check_stack_guard_page(vma, address) < 0)
2594
		return VM_FAULT_SIGSEGV;
2595

2596
	/* Use the zero-page for reads */
2597
	if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
H
Hugh Dickins 已提交
2598 2599
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
2600
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2601 2602 2603 2604 2605
		if (!pte_none(*page_table))
			goto unlock;
		goto setpte;
	}

N
Nick Piggin 已提交
2606 2607 2608 2609 2610 2611
	/* 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;
2612 2613 2614 2615 2616
	/*
	 * 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
2617
	__SetPageUptodate(page);
2618

2619
	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg))
2620 2621
		goto oom_free_page;

N
Nick Piggin 已提交
2622
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
2623 2624
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
2625

N
Nick Piggin 已提交
2626
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2627
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
2628
		goto release;
H
Hugh Dickins 已提交
2629

2630
	inc_mm_counter_fast(mm, MM_ANONPAGES);
N
Nick Piggin 已提交
2631
	page_add_new_anon_rmap(page, vma, address);
2632 2633
	mem_cgroup_commit_charge(page, memcg, false);
	lru_cache_add_active_or_unevictable(page, vma);
H
Hugh Dickins 已提交
2634
setpte:
2635
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2636 2637

	/* No need to invalidate - it was non-present before */
2638
	update_mmu_cache(vma, address, page_table);
2639
unlock:
2640
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2641
	return 0;
2642
release:
2643
	mem_cgroup_cancel_charge(page, memcg);
2644 2645
	page_cache_release(page);
	goto unlock;
2646
oom_free_page:
2647
	page_cache_release(page);
2648
oom:
L
Linus Torvalds 已提交
2649 2650 2651
	return VM_FAULT_OOM;
}

2652 2653 2654 2655 2656
/*
 * The mmap_sem must have been held on entry, and may have been
 * released depending on flags and vma->vm_ops->fault() return value.
 * See filemap_fault() and __lock_page_retry().
 */
2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687
static int __do_fault(struct vm_area_struct *vma, unsigned long address,
		pgoff_t pgoff, unsigned int flags, struct page **page)
{
	struct vm_fault vmf;
	int ret;

	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;

	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		return ret;

	if (unlikely(PageHWPoison(vmf.page))) {
		if (ret & VM_FAULT_LOCKED)
			unlock_page(vmf.page);
		page_cache_release(vmf.page);
		return VM_FAULT_HWPOISON;
	}

	if (unlikely(!(ret & VM_FAULT_LOCKED)))
		lock_page(vmf.page);
	else
		VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);

	*page = vmf.page;
	return ret;
}

2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703
/**
 * do_set_pte - setup new PTE entry for given page and add reverse page mapping.
 *
 * @vma: virtual memory area
 * @address: user virtual address
 * @page: page to map
 * @pte: pointer to target page table entry
 * @write: true, if new entry is writable
 * @anon: true, if it's anonymous page
 *
 * Caller must hold page table lock relevant for @pte.
 *
 * Target users are page handler itself and implementations of
 * vm_ops->map_pages.
 */
void do_set_pte(struct vm_area_struct *vma, unsigned long address,
2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724
		struct page *page, pte_t *pte, bool write, bool anon)
{
	pte_t entry;

	flush_icache_page(vma, page);
	entry = mk_pte(page, vma->vm_page_prot);
	if (write)
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
	if (anon) {
		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
		page_add_new_anon_rmap(page, vma, address);
	} else {
		inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES);
		page_add_file_rmap(page);
	}
	set_pte_at(vma->vm_mm, address, pte, entry);

	/* no need to invalidate: a not-present page won't be cached */
	update_mmu_cache(vma, address, pte);
}

2725 2726
static unsigned long fault_around_bytes __read_mostly =
	rounddown_pow_of_two(65536);
2727 2728 2729

#ifdef CONFIG_DEBUG_FS
static int fault_around_bytes_get(void *data, u64 *val)
2730
{
2731
	*val = fault_around_bytes;
2732 2733 2734
	return 0;
}

2735 2736 2737 2738 2739
/*
 * fault_around_pages() and fault_around_mask() expects fault_around_bytes
 * rounded down to nearest page order. It's what do_fault_around() expects to
 * see.
 */
2740
static int fault_around_bytes_set(void *data, u64 val)
2741
{
2742
	if (val / PAGE_SIZE > PTRS_PER_PTE)
2743
		return -EINVAL;
2744 2745 2746 2747
	if (val > PAGE_SIZE)
		fault_around_bytes = rounddown_pow_of_two(val);
	else
		fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
2748 2749
	return 0;
}
2750 2751
DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
		fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
2752 2753 2754 2755 2756

static int __init fault_around_debugfs(void)
{
	void *ret;

2757 2758
	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
			&fault_around_bytes_fops);
2759
	if (!ret)
2760
		pr_warn("Failed to create fault_around_bytes in debugfs");
2761 2762 2763 2764
	return 0;
}
late_initcall(fault_around_debugfs);
#endif
2765

2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788
/*
 * do_fault_around() tries to map few pages around the fault address. The hope
 * is that the pages will be needed soon and this will lower the number of
 * faults to handle.
 *
 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
 * not ready to be mapped: not up-to-date, locked, etc.
 *
 * This function is called with the page table lock taken. In the split ptlock
 * case the page table lock only protects only those entries which belong to
 * the page table corresponding to the fault address.
 *
 * This function doesn't cross the VMA boundaries, in order to call map_pages()
 * only once.
 *
 * fault_around_pages() defines how many pages we'll try to map.
 * do_fault_around() expects it to return a power of two less than or equal to
 * PTRS_PER_PTE.
 *
 * The virtual address of the area that we map is naturally aligned to the
 * fault_around_pages() value (and therefore to page order).  This way it's
 * easier to guarantee that we don't cross page table boundaries.
 */
2789 2790 2791
static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pgoff_t pgoff, unsigned int flags)
{
2792
	unsigned long start_addr, nr_pages, mask;
2793 2794 2795 2796
	pgoff_t max_pgoff;
	struct vm_fault vmf;
	int off;

2797 2798 2799 2800
	nr_pages = ACCESS_ONCE(fault_around_bytes) >> PAGE_SHIFT;
	mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;

	start_addr = max(address & mask, vma->vm_start);
2801 2802 2803 2804 2805 2806
	off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
	pte -= off;
	pgoff -= off;

	/*
	 *  max_pgoff is either end of page table or end of vma
2807
	 *  or fault_around_pages() from pgoff, depending what is nearest.
2808 2809 2810 2811
	 */
	max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
		PTRS_PER_PTE - 1;
	max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1,
2812
			pgoff + nr_pages - 1);
2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831

	/* Check if it makes any sense to call ->map_pages */
	while (!pte_none(*pte)) {
		if (++pgoff > max_pgoff)
			return;
		start_addr += PAGE_SIZE;
		if (start_addr >= vma->vm_end)
			return;
		pte++;
	}

	vmf.virtual_address = (void __user *) start_addr;
	vmf.pte = pte;
	vmf.pgoff = pgoff;
	vmf.max_pgoff = max_pgoff;
	vmf.flags = flags;
	vma->vm_ops->map_pages(vma, &vmf);
}

2832 2833 2834 2835 2836 2837
static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pmd_t *pmd,
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
{
	struct page *fault_page;
	spinlock_t *ptl;
2838
	pte_t *pte;
2839 2840 2841 2842 2843 2844 2845
	int ret = 0;

	/*
	 * Let's call ->map_pages() first and use ->fault() as fallback
	 * if page by the offset is not ready to be mapped (cold cache or
	 * something).
	 */
2846
	if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
2847 2848 2849 2850 2851 2852
		pte = pte_offset_map_lock(mm, pmd, address, &ptl);
		do_fault_around(vma, address, pte, pgoff, flags);
		if (!pte_same(*pte, orig_pte))
			goto unlock_out;
		pte_unmap_unlock(pte, ptl);
	}
2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864

	ret = __do_fault(vma, address, pgoff, flags, &fault_page);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		return ret;

	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (unlikely(!pte_same(*pte, orig_pte))) {
		pte_unmap_unlock(pte, ptl);
		unlock_page(fault_page);
		page_cache_release(fault_page);
		return ret;
	}
2865
	do_set_pte(vma, address, fault_page, pte, false, false);
2866
	unlock_page(fault_page);
2867 2868
unlock_out:
	pte_unmap_unlock(pte, ptl);
2869 2870 2871
	return ret;
}

2872 2873 2874 2875 2876
static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pmd_t *pmd,
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
{
	struct page *fault_page, *new_page;
2877
	struct mem_cgroup *memcg;
2878
	spinlock_t *ptl;
2879
	pte_t *pte;
2880 2881 2882 2883 2884 2885 2886 2887 2888
	int ret;

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

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

2889
	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg)) {
2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907
		page_cache_release(new_page);
		return VM_FAULT_OOM;
	}

	ret = __do_fault(vma, address, pgoff, flags, &fault_page);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		goto uncharge_out;

	copy_user_highpage(new_page, fault_page, address, vma);
	__SetPageUptodate(new_page);

	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (unlikely(!pte_same(*pte, orig_pte))) {
		pte_unmap_unlock(pte, ptl);
		unlock_page(fault_page);
		page_cache_release(fault_page);
		goto uncharge_out;
	}
2908
	do_set_pte(vma, address, new_page, pte, true, true);
2909 2910
	mem_cgroup_commit_charge(new_page, memcg, false);
	lru_cache_add_active_or_unevictable(new_page, vma);
2911 2912 2913 2914 2915
	pte_unmap_unlock(pte, ptl);
	unlock_page(fault_page);
	page_cache_release(fault_page);
	return ret;
uncharge_out:
2916
	mem_cgroup_cancel_charge(new_page, memcg);
2917 2918 2919 2920
	page_cache_release(new_page);
	return ret;
}

2921
static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2922
		unsigned long address, pmd_t *pmd,
2923
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2924
{
2925 2926
	struct page *fault_page;
	struct address_space *mapping;
2927
	spinlock_t *ptl;
2928
	pte_t *pte;
2929 2930
	int dirtied = 0;
	int ret, tmp;
2931

2932 2933
	ret = __do_fault(vma, address, pgoff, flags, &fault_page);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2934
		return ret;
L
Linus Torvalds 已提交
2935 2936

	/*
2937 2938
	 * Check if the backing address space wants to know that the page is
	 * about to become writable
L
Linus Torvalds 已提交
2939
	 */
2940 2941 2942 2943 2944
	if (vma->vm_ops->page_mkwrite) {
		unlock_page(fault_page);
		tmp = do_page_mkwrite(vma, fault_page, address);
		if (unlikely(!tmp ||
				(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2945
			page_cache_release(fault_page);
2946
			return tmp;
2947
		}
2948 2949
	}

2950 2951 2952 2953 2954 2955
	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (unlikely(!pte_same(*pte, orig_pte))) {
		pte_unmap_unlock(pte, ptl);
		unlock_page(fault_page);
		page_cache_release(fault_page);
		return ret;
L
Linus Torvalds 已提交
2956
	}
2957
	do_set_pte(vma, address, fault_page, pte, true, false);
2958
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
2959

2960 2961
	if (set_page_dirty(fault_page))
		dirtied = 1;
2962 2963 2964 2965 2966 2967
	/*
	 * Take a local copy of the address_space - page.mapping may be zeroed
	 * by truncate after unlock_page().   The address_space itself remains
	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
	 * release semantics to prevent the compiler from undoing this copying.
	 */
2968 2969 2970 2971 2972 2973 2974 2975
	mapping = fault_page->mapping;
	unlock_page(fault_page);
	if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
		/*
		 * Some device drivers do not set page.mapping but still
		 * dirty their pages
		 */
		balance_dirty_pages_ratelimited(mapping);
2976
	}
2977

2978 2979 2980
	/* file_update_time outside page_lock */
	if (vma->vm_file && !vma->vm_ops->page_mkwrite)
		file_update_time(vma->vm_file);
N
Nick Piggin 已提交
2981

2982
	return ret;
2983
}
2984

2985 2986 2987 2988 2989 2990
/*
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults).
 * The mmap_sem may have been released depending on flags and our
 * return value.  See filemap_fault() and __lock_page_or_retry().
 */
2991
static int do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2992
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2993
		unsigned int flags, pte_t orig_pte)
2994 2995
{
	pgoff_t pgoff = (((address & PAGE_MASK)
2996
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2997

2998
	pte_unmap(page_table);
2999 3000 3001
	if (!(flags & FAULT_FLAG_WRITE))
		return do_read_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3002 3003 3004
	if (!(vma->vm_flags & VM_SHARED))
		return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3005
	return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3006 3007
}

3008
static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3009 3010
				unsigned long addr, int page_nid,
				int *flags)
3011 3012 3013 3014
{
	get_page(page);

	count_vm_numa_event(NUMA_HINT_FAULTS);
3015
	if (page_nid == numa_node_id()) {
3016
		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3017 3018
		*flags |= TNF_FAULT_LOCAL;
	}
3019 3020 3021 3022

	return mpol_misplaced(page, vma, addr);
}

3023
static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3024 3025
		   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
{
3026
	struct page *page = NULL;
3027
	spinlock_t *ptl;
3028
	int page_nid = -1;
3029
	int last_cpupid;
3030
	int target_nid;
3031
	bool migrated = false;
3032
	int flags = 0;
3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044

	/*
	* 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);
3045 3046 3047 3048 3049
	if (unlikely(!pte_same(*ptep, pte))) {
		pte_unmap_unlock(ptep, ptl);
		goto out;
	}

3050 3051 3052 3053 3054 3055 3056 3057 3058
	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;
	}
3059
	BUG_ON(is_zero_pfn(page_to_pfn(page)));
3060

3061 3062 3063 3064 3065 3066 3067 3068
	/*
	 * Avoid grouping on DSO/COW pages in specific and RO pages
	 * in general, RO pages shouldn't hurt as much anyway since
	 * they can be in shared cache state.
	 */
	if (!pte_write(pte))
		flags |= TNF_NO_GROUP;

3069 3070 3071 3072 3073 3074 3075
	/*
	 * Flag if the page is shared between multiple address spaces. This
	 * is later used when determining whether to group tasks together
	 */
	if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
		flags |= TNF_SHARED;

3076
	last_cpupid = page_cpupid_last(page);
3077
	page_nid = page_to_nid(page);
3078
	target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3079
	pte_unmap_unlock(ptep, ptl);
3080 3081 3082 3083 3084 3085
	if (target_nid == -1) {
		put_page(page);
		goto out;
	}

	/* Migrate to the requested node */
3086
	migrated = migrate_misplaced_page(page, vma, target_nid);
3087
	if (migrated) {
3088
		page_nid = target_nid;
3089 3090
		flags |= TNF_MIGRATED;
	}
3091 3092

out:
3093
	if (page_nid != -1)
3094
		task_numa_fault(last_cpupid, page_nid, 1, flags);
3095 3096 3097
	return 0;
}

L
Linus Torvalds 已提交
3098 3099 3100 3101 3102 3103 3104 3105 3106
/*
 * 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
3107 3108
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
3109 3110 3111 3112
 * We return with pte unmapped and unlocked.
 *
 * The mmap_sem may have been released depending on flags and our
 * return value.  See filemap_fault() and __lock_page_or_retry().
L
Linus Torvalds 已提交
3113
 */
3114
static int handle_pte_fault(struct mm_struct *mm,
3115 3116
		     struct vm_area_struct *vma, unsigned long address,
		     pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
3117 3118
{
	pte_t entry;
3119
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3120

3121 3122 3123 3124 3125 3126 3127 3128 3129 3130
	/*
	 * some architectures can have larger ptes than wordsize,
	 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and CONFIG_32BIT=y,
	 * so READ_ONCE or ACCESS_ONCE cannot guarantee atomic accesses.
	 * The code below just needs a consistent view for the ifs and
	 * we later double check anyway with the ptl lock held. So here
	 * a barrier will do.
	 */
	entry = *pte;
	barrier();
L
Linus Torvalds 已提交
3131
	if (!pte_present(entry)) {
3132
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
3133
			if (vma->vm_ops) {
N
Nick Piggin 已提交
3134
				if (likely(vma->vm_ops->fault))
3135 3136
					return do_fault(mm, vma, address, pte,
							pmd, flags, entry);
J
Jes Sorensen 已提交
3137 3138
			}
			return do_anonymous_page(mm, vma, address,
3139
						 pte, pmd, flags);
3140 3141
		}
		return do_swap_page(mm, vma, address,
3142
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
3143 3144
	}

3145 3146 3147
	if (pte_numa(entry))
		return do_numa_page(mm, vma, address, entry, pte, pmd);

H
Hugh Dickins 已提交
3148
	ptl = pte_lockptr(mm, pmd);
3149 3150 3151
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
3152
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3153
		if (!pte_write(entry))
3154 3155
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
3156 3157 3158
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
3159
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3160
		update_mmu_cache(vma, address, pte);
3161 3162 3163 3164 3165 3166 3167
	} 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.
		 */
3168
		if (flags & FAULT_FLAG_WRITE)
3169
			flush_tlb_fix_spurious_fault(vma, address);
3170
	}
3171 3172
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3173
	return 0;
L
Linus Torvalds 已提交
3174 3175 3176 3177
}

/*
 * By the time we get here, we already hold the mm semaphore
3178 3179 3180
 *
 * The mmap_sem may have been released depending on flags and our
 * return value.  See filemap_fault() and __lock_page_or_retry().
L
Linus Torvalds 已提交
3181
 */
3182 3183
static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
			     unsigned long address, unsigned int flags)
L
Linus Torvalds 已提交
3184 3185 3186 3187 3188 3189
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

3190
	if (unlikely(is_vm_hugetlb_page(vma)))
3191
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3192 3193 3194 3195

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3196
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3197 3198
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3199
		return VM_FAULT_OOM;
3200
	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3201
		int ret = VM_FAULT_FALLBACK;
3202
		if (!vma->vm_ops)
3203 3204 3205 3206
			ret = do_huge_pmd_anonymous_page(mm, vma, address,
					pmd, flags);
		if (!(ret & VM_FAULT_FALLBACK))
			return ret;
3207 3208
	} else {
		pmd_t orig_pmd = *pmd;
3209 3210
		int ret;

3211 3212
		barrier();
		if (pmd_trans_huge(orig_pmd)) {
3213 3214
			unsigned int dirty = flags & FAULT_FLAG_WRITE;

3215 3216 3217 3218 3219 3220 3221 3222
			/*
			 * 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;

3223
			if (pmd_numa(orig_pmd))
3224
				return do_huge_pmd_numa_page(mm, vma, address,
3225 3226
							     orig_pmd, pmd);

3227
			if (dirty && !pmd_write(orig_pmd)) {
3228 3229
				ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
							  orig_pmd);
3230 3231
				if (!(ret & VM_FAULT_FALLBACK))
					return ret;
3232 3233 3234
			} else {
				huge_pmd_set_accessed(mm, vma, address, pmd,
						      orig_pmd, dirty);
3235
				return 0;
3236
			}
3237 3238 3239 3240 3241 3242 3243 3244
		}
	}

	/*
	 * 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.
	 */
3245 3246
	if (unlikely(pmd_none(*pmd)) &&
	    unlikely(__pte_alloc(mm, vma, pmd, address)))
H
Hugh Dickins 已提交
3247
		return VM_FAULT_OOM;
3248 3249 3250 3251 3252 3253 3254 3255 3256 3257
	/* 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
3258

3259
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3260 3261
}

3262 3263 3264 3265 3266 3267
/*
 * By the time we get here, we already hold the mm semaphore
 *
 * The mmap_sem may have been released depending on flags and our
 * return value.  See filemap_fault() and __lock_page_or_retry().
 */
3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		    unsigned long address, unsigned int flags)
{
	int ret;

	__set_current_state(TASK_RUNNING);

	count_vm_event(PGFAULT);
	mem_cgroup_count_vm_event(mm, PGFAULT);

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

	/*
	 * Enable the memcg OOM handling for faults triggered in user
	 * space.  Kernel faults are handled more gracefully.
	 */
	if (flags & FAULT_FLAG_USER)
3286
		mem_cgroup_oom_enable();
3287 3288 3289

	ret = __handle_mm_fault(mm, vma, address, flags);

3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300
	if (flags & FAULT_FLAG_USER) {
		mem_cgroup_oom_disable();
                /*
                 * The task may have entered a memcg OOM situation but
                 * if the allocation error was handled gracefully (no
                 * VM_FAULT_OOM), there is no need to kill anything.
                 * Just clean up the OOM state peacefully.
                 */
                if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
                        mem_cgroup_oom_synchronize(false);
	}
3301

3302 3303
	return ret;
}
3304
EXPORT_SYMBOL_GPL(handle_mm_fault);
3305

L
Linus Torvalds 已提交
3306 3307 3308
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3309
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3310
 */
3311
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3312
{
H
Hugh Dickins 已提交
3313 3314
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3315
		return -ENOMEM;
L
Linus Torvalds 已提交
3316

3317 3318
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3319
	spin_lock(&mm->page_table_lock);
3320
	if (pgd_present(*pgd))		/* Another has populated it */
3321
		pud_free(mm, new);
3322 3323
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3324
	spin_unlock(&mm->page_table_lock);
3325
	return 0;
L
Linus Torvalds 已提交
3326 3327 3328 3329 3330 3331
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3332
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3333
 */
3334
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3335
{
H
Hugh Dickins 已提交
3336 3337
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3338
		return -ENOMEM;
L
Linus Torvalds 已提交
3339

3340 3341
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3342
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3343
#ifndef __ARCH_HAS_4LEVEL_HACK
3344
	if (pud_present(*pud))		/* Another has populated it */
3345
		pmd_free(mm, new);
3346 3347
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3348
#else
3349
	if (pgd_present(*pud))		/* Another has populated it */
3350
		pmd_free(mm, new);
3351 3352
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3353
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3354
	spin_unlock(&mm->page_table_lock);
3355
	return 0;
3356
}
L
Linus Torvalds 已提交
3357 3358
#endif /* __PAGETABLE_PMD_FOLDED */

3359
static int __follow_pte(struct mm_struct *mm, unsigned long address,
J
Johannes Weiner 已提交
3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375
		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);
3376
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396
	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;
}

3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 3407
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
3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429 3430 3431 3432 3433 3434 3435 3436
/**
 * 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);

3437
#ifdef CONFIG_HAVE_IOREMAP_PROT
3438 3439 3440
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3441
{
3442
	int ret = -EINVAL;
3443 3444 3445
	pte_t *ptep, pte;
	spinlock_t *ptl;

3446 3447
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3448

3449
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3450
		goto out;
3451
	pte = *ptep;
3452

3453 3454 3455 3456
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3457
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3458

3459
	ret = 0;
3460 3461 3462
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3463
	return ret;
3464 3465 3466 3467 3468 3469 3470
}

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
3471
	void __iomem *maddr;
3472 3473
	int offset = addr & (PAGE_SIZE-1);

3474
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3475 3476 3477 3478 3479 3480 3481 3482 3483 3484 3485
		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;
}
3486
EXPORT_SYMBOL_GPL(generic_access_phys);
3487 3488
#endif

3489
/*
3490 3491
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
3492
 */
3493 3494
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long addr, void *buf, int len, int write)
3495 3496 3497 3498 3499
{
	struct vm_area_struct *vma;
	void *old_buf = buf;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3500
	/* ignore errors, just check how much was successfully transferred */
3501 3502 3503
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3504
		struct page *page = NULL;
3505 3506 3507

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3508
		if (ret <= 0) {
3509 3510 3511
#ifndef CONFIG_HAVE_IOREMAP_PROT
			break;
#else
3512 3513 3514 3515 3516
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
			vma = find_vma(mm, addr);
3517
			if (!vma || vma->vm_start > addr)
3518 3519 3520 3521 3522 3523 3524
				break;
			if (vma->vm_ops && vma->vm_ops->access)
				ret = vma->vm_ops->access(vma, addr, buf,
							  len, write);
			if (ret <= 0)
				break;
			bytes = ret;
3525
#endif
3526
		} else {
3527 3528 3529 3530 3531 3532 3533 3534 3535 3536 3537 3538 3539 3540 3541 3542
			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);
3543 3544 3545 3546 3547 3548 3549 3550 3551
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
3552

S
Stephen Wilson 已提交
3553
/**
3554
 * access_remote_vm - access another process' address space
S
Stephen Wilson 已提交
3555 3556 3557 3558 3559 3560 3561 3562 3563 3564 3565 3566 3567 3568
 * @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);
}

3569 3570 3571 3572 3573 3574 3575 3576 3577 3578 3579 3580 3581 3582 3583 3584 3585 3586 3587 3588 3589
/*
 * 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;
}

3590 3591 3592 3593 3594 3595 3596 3597
/*
 * 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;

3598 3599 3600 3601 3602 3603 3604
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3605 3606 3607 3608 3609 3610
	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) {
A
Andy Shevchenko 已提交
3611
			char *p;
3612

3613
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3614 3615
			if (IS_ERR(p))
				p = "?";
A
Andy Shevchenko 已提交
3616
			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3617 3618 3619 3620 3621
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
3622
	up_read(&mm->mmap_sem);
3623
}
3624

3625
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3626 3627
void might_fault(void)
{
3628 3629 3630 3631 3632 3633 3634 3635 3636
	/*
	 * 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;

3637 3638 3639 3640 3641
	/*
	 * 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.
	 */
3642 3643 3644 3645 3646 3647
	if (in_atomic())
		return;

	__might_sleep(__FILE__, __LINE__, 0);

	if (current->mm)
3648 3649 3650 3651
		might_lock_read(&current->mm->mmap_sem);
}
EXPORT_SYMBOL(might_fault);
#endif
A
Andrea Arcangeli 已提交
3652 3653 3654 3655 3656 3657 3658 3659 3660 3661 3662 3663 3664 3665 3666 3667 3668 3669 3670 3671 3672 3673 3674 3675 3676 3677 3678 3679 3680 3681 3682 3683 3684 3685 3686 3687 3688 3689 3690 3691 3692 3693 3694 3695 3696 3697 3698 3699 3700 3701 3702 3703 3704 3705 3706 3707 3708 3709 3710 3711 3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 3722

#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 */
3723

3724
#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
3725 3726 3727 3728 3729 3730 3731 3732 3733

static struct kmem_cache *page_ptl_cachep;

void __init ptlock_cache_init(void)
{
	page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
			SLAB_PANIC, NULL);
}

3734
bool ptlock_alloc(struct page *page)
3735 3736 3737
{
	spinlock_t *ptl;

3738
	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
3739 3740
	if (!ptl)
		return false;
3741
	page->ptl = ptl;
3742 3743 3744
	return true;
}

3745
void ptlock_free(struct page *page)
3746
{
3747
	kmem_cache_free(page_ptl_cachep, page->ptl);
3748 3749
}
#endif