memory.c 102.3 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

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

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

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

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

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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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->start	= start;
	tlb->end	= end;
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	tlb->need_flush = 0;
	tlb->local.next = NULL;
	tlb->local.nr   = 0;
	tlb->local.max  = ARRAY_SIZE(tlb->__pages);
	tlb->active     = &tlb->local;
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	tlb->batch_count = 0;
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#ifdef CONFIG_HAVE_RCU_TABLE_FREE
	tlb->batch = NULL;
#endif
}

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static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
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{
	tlb->need_flush = 0;
	tlb_flush(tlb);
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
	tlb_table_flush(tlb);
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#endif
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}

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

	tlb->need_flush = 1;

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

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

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#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
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/*
 * 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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621 622
}

K
KAMEZAWA Hiroyuki 已提交
623 624 625 626 627 628
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)
629
{
K
KAMEZAWA Hiroyuki 已提交
630 631
	int i;

632
	if (current->mm == mm)
633
		sync_mm_rss(mm);
K
KAMEZAWA Hiroyuki 已提交
634 635 636
	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
637 638
}

N
Nick Piggin 已提交
639
/*
640 641 642
 * 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
643 644 645
 *
 * The calling function must still handle the error.
 */
646 647
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
648
{
649 650 651 652 653
	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;
654 655 656 657 658 659 660 661 662 663 664 665 666 667
	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) {
668 669
			printk(KERN_ALERT
				"BUG: Bad page map: %lu messages suppressed\n",
670 671 672 673 674 675 676
				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
677 678 679 680

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

681 682
	printk(KERN_ALERT
		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
683 684
		current->comm,
		(long long)pte_val(pte), (long long)pmd_val(*pmd));
685
	if (page)
686
		dump_page(page, "bad pte");
687
	printk(KERN_ALERT
688 689 690 691 692 693
		"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
694 695
		printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
		       vma->vm_ops->fault);
A
Al Viro 已提交
696
	if (vma->vm_file)
J
Joe Perches 已提交
697 698
		printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
		       vma->vm_file->f_op->mmap);
N
Nick Piggin 已提交
699
	dump_stack();
700
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
N
Nick Piggin 已提交
701 702
}

H
Hugh Dickins 已提交
703
/*
N
Nick Piggin 已提交
704
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
705
 *
N
Nick Piggin 已提交
706 707 708
 * "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
709
 *
N
Nick Piggin 已提交
710 711 712 713 714 715 716 717
 * 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.
718
 *
J
Jared Hulbert 已提交
719 720
 * 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
721 722
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
723 724 725
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
726 727 728 729 730 731
 * 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
732 733
 *
 *
N
Nick Piggin 已提交
734
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
735 736 737 738 739 740 741 742 743
 *
 * 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
744
 */
N
Nick Piggin 已提交
745 746 747 748 749 750 751
#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
752
{
753
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
754 755

	if (HAVE_PTE_SPECIAL) {
756
		if (likely(!pte_special(pte)))
757
			goto check_pfn;
H
Hugh Dickins 已提交
758 759
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
760
		if (!is_zero_pfn(pfn))
761
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
762 763 764 765 766
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
767 768 769 770 771 772
	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
773 774
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
775 776 777 778 779
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
780 781
	}

782 783
	if (is_zero_pfn(pfn))
		return NULL;
784 785 786 787 788
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
789 790

	/*
N
Nick Piggin 已提交
791 792
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
793
	 */
J
Jared Hulbert 已提交
794
out:
795
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
796 797
}

L
Linus Torvalds 已提交
798 799 800 801 802 803
/*
 * 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
804
static inline unsigned long
L
Linus Torvalds 已提交
805
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
806
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
807
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
808
{
N
Nick Piggin 已提交
809
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
810 811 812 813 814 815
	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)) {
816 817
			swp_entry_t entry = pte_to_swp_entry(pte);

H
Hugh Dickins 已提交
818 819 820
			if (swap_duplicate(entry) < 0)
				return entry.val;

L
Linus Torvalds 已提交
821 822 823
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
824 825 826
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
827 828
				spin_unlock(&mmlist_lock);
			}
K
KAMEZAWA Hiroyuki 已提交
829 830
			if (likely(!non_swap_entry(entry)))
				rss[MM_SWAPENTS]++;
831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846
			else if (is_migration_entry(entry)) {
				page = migration_entry_to_page(entry);

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

				if (is_write_migration_entry(entry) &&
				    is_cow_mapping(vm_flags)) {
					/*
					 * COW mappings require pages in both
					 * parent and child to be set to read.
					 */
					make_migration_entry_read(&entry);
					pte = swp_entry_to_pte(entry);
847 848
					if (pte_swp_soft_dirty(*src_pte))
						pte = pte_swp_mksoft_dirty(pte);
849 850
					set_pte_at(src_mm, addr, src_pte, pte);
				}
851
			}
L
Linus Torvalds 已提交
852
		}
853
		goto out_set_pte;
L
Linus Torvalds 已提交
854 855 856 857 858 859
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
860
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
861
		ptep_set_wrprotect(src_mm, addr, src_pte);
862
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
863 864 865 866 867 868 869 870 871
	}

	/*
	 * 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);
872 873 874 875

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
H
Hugh Dickins 已提交
876
		page_dup_rmap(page);
K
KAMEZAWA Hiroyuki 已提交
877 878 879 880
		if (PageAnon(page))
			rss[MM_ANONPAGES]++;
		else
			rss[MM_FILEPAGES]++;
881
	}
882 883 884

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
885
	return 0;
L
Linus Torvalds 已提交
886 887
}

888
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
889 890
		   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
891
{
892
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
893
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
894
	spinlock_t *src_ptl, *dst_ptl;
895
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
896
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
897
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
898 899

again:
K
KAMEZAWA Hiroyuki 已提交
900 901
	init_rss_vec(rss);

H
Hugh Dickins 已提交
902
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
903 904
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
905
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
906
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
907
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
908 909
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
910
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
911 912 913 914 915 916

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
917 918 919
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
920
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
921 922
				break;
		}
L
Linus Torvalds 已提交
923 924 925 926
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
927 928 929 930
		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
931 932 933
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

934
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
935
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
936
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
937
	add_mm_rss_vec(dst_mm, rss);
938
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
939
	cond_resched();
H
Hugh Dickins 已提交
940 941 942 943 944 945

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963
	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);
964 965
		if (pmd_trans_huge(*src_pmd)) {
			int err;
966
			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
967 968 969 970 971 972 973 974
			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
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 1012
		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;
1013 1014 1015
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	bool is_cow;
A
Andrea Arcangeli 已提交
1016
	int ret;
L
Linus Torvalds 已提交
1017

1018 1019 1020 1021 1022 1023
	/*
	 * 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.
	 */
1024 1025
	if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR |
			       VM_PFNMAP | VM_MIXEDMAP))) {
1026 1027 1028 1029
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
1030 1031 1032
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

1033
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1034 1035 1036 1037
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
1038
		ret = track_pfn_copy(vma);
1039 1040 1041 1042
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
1043 1044 1045 1046 1047 1048
	/*
	 * 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.
	 */
1049 1050 1051 1052 1053 1054
	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
1055 1056

	ret = 0;
L
Linus Torvalds 已提交
1057 1058 1059 1060 1061 1062
	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
1063 1064 1065 1066 1067
		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
1068
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1069

1070 1071
	if (is_cow)
		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
A
Andrea Arcangeli 已提交
1072
	return ret;
L
Linus Torvalds 已提交
1073 1074
}

1075
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1076
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
1077
				unsigned long addr, unsigned long end,
1078
				struct zap_details *details)
L
Linus Torvalds 已提交
1079
{
N
Nick Piggin 已提交
1080
	struct mm_struct *mm = tlb->mm;
P
Peter Zijlstra 已提交
1081
	int force_flush = 0;
K
KAMEZAWA Hiroyuki 已提交
1082
	int rss[NR_MM_COUNTERS];
1083
	spinlock_t *ptl;
1084
	pte_t *start_pte;
1085
	pte_t *pte;
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 1112 1113 1114 1115 1116 1117 1118 1119
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
				    details->check_mapping != page->mapping)
					continue;
				/*
				 * Each page->index must be checked when
				 * invalidating or truncating nonlinear.
				 */
				if (details->nonlinear_vma &&
				    (page->index < details->first_index ||
				     page->index > details->last_index))
					continue;
			}
N
Nick Piggin 已提交
1120
			ptent = ptep_get_and_clear_full(mm, addr, pte,
1121
							tlb->fullmm);
L
Linus Torvalds 已提交
1122 1123 1124 1125 1126
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (unlikely(details) && details->nonlinear_vma
			    && linear_page_index(details->nonlinear_vma,
1127 1128 1129
						addr) != page->index) {
				pte_t ptfile = pgoff_to_pte(page->index);
				if (pte_soft_dirty(ptent))
1130
					ptfile = pte_file_mksoft_dirty(ptfile);
1131 1132
				set_pte_at(mm, addr, pte, ptfile);
			}
L
Linus Torvalds 已提交
1133
			if (PageAnon(page))
K
KAMEZAWA Hiroyuki 已提交
1134
				rss[MM_ANONPAGES]--;
1135
			else {
1136 1137
				if (pte_dirty(ptent)) {
					force_flush = 1;
1138
					set_page_dirty(page);
1139
				}
1140
				if (pte_young(ptent) &&
1141
				    likely(!(vma->vm_flags & VM_SEQ_READ)))
1142
					mark_page_accessed(page);
K
KAMEZAWA Hiroyuki 已提交
1143
				rss[MM_FILEPAGES]--;
1144
			}
1145
			page_remove_rmap(page);
1146 1147
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
1148 1149
			if (unlikely(!__tlb_remove_page(tlb, page))) {
				force_flush = 1;
1150
				addr += PAGE_SIZE;
P
Peter Zijlstra 已提交
1151
				break;
1152
			}
L
Linus Torvalds 已提交
1153 1154 1155 1156 1157 1158 1159 1160
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
1161 1162 1163
		if (pte_file(ptent)) {
			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
				print_bad_pte(vma, addr, ptent, NULL);
K
KAMEZAWA Hiroyuki 已提交
1164 1165 1166 1167 1168
		} else {
			swp_entry_t entry = pte_to_swp_entry(ptent);

			if (!non_swap_entry(entry))
				rss[MM_SWAPENTS]--;
1169 1170 1171 1172 1173 1174 1175 1176 1177 1178
			else if (is_migration_entry(entry)) {
				struct page *page;

				page = migration_entry_to_page(entry);

				if (PageAnon(page))
					rss[MM_ANONPAGES]--;
				else
					rss[MM_FILEPAGES]--;
			}
K
KAMEZAWA Hiroyuki 已提交
1179 1180 1181
			if (unlikely(!free_swap_and_cache(entry)))
				print_bad_pte(vma, addr, ptent, NULL);
		}
1182
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1183
	} while (pte++, addr += PAGE_SIZE, addr != end);
1184

K
KAMEZAWA Hiroyuki 已提交
1185
	add_mm_rss_vec(mm, rss);
1186
	arch_leave_lazy_mmu_mode();
1187

1188
	/* Do the actual TLB flush before dropping ptl */
P
Peter Zijlstra 已提交
1189
	if (force_flush) {
1190 1191 1192 1193 1194 1195 1196 1197
		unsigned long old_end;

		/*
		 * Flush the TLB just for the previous segment,
		 * then update the range to be the remaining
		 * TLB range.
		 */
		old_end = tlb->end;
1198
		tlb->end = addr;
1199
		tlb_flush_mmu_tlbonly(tlb);
1200 1201
		tlb->start = addr;
		tlb->end = old_end;
1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213
	}
	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);
1214 1215

		if (addr != end)
P
Peter Zijlstra 已提交
1216 1217 1218
			goto again;
	}

1219
	return addr;
L
Linus Torvalds 已提交
1220 1221
}

1222
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1223
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
1224
				unsigned long addr, unsigned long end,
1225
				struct zap_details *details)
L
Linus Torvalds 已提交
1226 1227 1228 1229 1230 1231 1232
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1233
		if (pmd_trans_huge(*pmd)) {
1234
			if (next - addr != HPAGE_PMD_SIZE) {
1235 1236 1237 1238 1239 1240 1241 1242 1243
#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
1244
				split_huge_page_pmd(vma, addr, pmd);
S
Shaohua Li 已提交
1245
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1246
				goto next;
1247 1248
			/* fall through */
		}
1249 1250 1251 1252 1253 1254 1255 1256 1257
		/*
		 * 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;
1258
		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1259
next:
1260 1261
		cond_resched();
	} while (pmd++, addr = next, addr != end);
1262 1263

	return addr;
L
Linus Torvalds 已提交
1264 1265
}

1266
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1267
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1268
				unsigned long addr, unsigned long end,
1269
				struct zap_details *details)
L
Linus Torvalds 已提交
1270 1271 1272 1273 1274 1275 1276
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1277
		if (pud_none_or_clear_bad(pud))
L
Linus Torvalds 已提交
1278
			continue;
1279 1280
		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
	} while (pud++, addr = next, addr != end);
1281 1282

	return addr;
L
Linus Torvalds 已提交
1283 1284
}

A
Al Viro 已提交
1285 1286 1287 1288
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
1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300
{
	pgd_t *pgd;
	unsigned long next;

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

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

1308 1309 1310

static void unmap_single_vma(struct mmu_gather *tlb,
		struct vm_area_struct *vma, unsigned long start_addr,
1311
		unsigned long end_addr,
1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322
		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;

1323 1324 1325
	if (vma->vm_file)
		uprobe_munmap(vma, start, end);

1326
	if (unlikely(vma->vm_flags & VM_PFNMAP))
1327
		untrack_pfn(vma, 0, 0);
1328 1329 1330 1331 1332 1333 1334

	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
1335
			 * cleanup path of mmap_region. When
1336
			 * hugetlbfs ->mmap method fails,
1337
			 * mmap_region() nullifies vma->vm_file
1338 1339 1340 1341
			 * before calling this function to clean up.
			 * Since no pte has actually been setup, it is
			 * safe to do nothing in this case.
			 */
1342 1343
			if (vma->vm_file) {
				mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1344
				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1345 1346
				mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
			}
1347 1348 1349
		} else
			unmap_page_range(tlb, vma, start, end, details);
	}
L
Linus Torvalds 已提交
1350 1351 1352 1353
}

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
1354
 * @tlb: address of the caller's struct mmu_gather
L
Linus Torvalds 已提交
1355 1356 1357 1358
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 *
1359
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1360 1361 1362 1363 1364 1365 1366 1367 1368 1369
 *
 * 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
1370
void unmap_vmas(struct mmu_gather *tlb,
L
Linus Torvalds 已提交
1371
		struct vm_area_struct *vma, unsigned long start_addr,
1372
		unsigned long end_addr)
L
Linus Torvalds 已提交
1373
{
A
Andrea Arcangeli 已提交
1374
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1375

A
Andrea Arcangeli 已提交
1376
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1377
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1378
		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
A
Andrea Arcangeli 已提交
1379
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1380 1381 1382 1383 1384
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
1385
 * @start: starting address of pages to zap
L
Linus Torvalds 已提交
1386 1387
 * @size: number of bytes to zap
 * @details: details of nonlinear truncation or shared cache invalidation
1388 1389
 *
 * Caller must protect the VMA list
L
Linus Torvalds 已提交
1390
 */
1391
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
L
Linus Torvalds 已提交
1392 1393 1394
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1395
	struct mmu_gather tlb;
1396
	unsigned long end = start + size;
L
Linus Torvalds 已提交
1397 1398

	lru_add_drain();
1399
	tlb_gather_mmu(&tlb, mm, start, end);
1400
	update_hiwater_rss(mm);
1401 1402
	mmu_notifier_invalidate_range_start(mm, start, end);
	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1403
		unmap_single_vma(&tlb, vma, start, end, details);
1404 1405
	mmu_notifier_invalidate_range_end(mm, start, end);
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
1406 1407
}

1408 1409 1410 1411 1412 1413 1414 1415
/**
 * zap_page_range_single - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 * @details: details of nonlinear truncation or shared cache invalidation
 *
 * The range must fit into one VMA.
L
Linus Torvalds 已提交
1416
 */
1417
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1418 1419 1420
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1421
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1422 1423 1424
	unsigned long end = address + size;

	lru_add_drain();
1425
	tlb_gather_mmu(&tlb, mm, address, end);
1426
	update_hiwater_rss(mm);
1427
	mmu_notifier_invalidate_range_start(mm, address, end);
1428
	unmap_single_vma(&tlb, vma, address, end, details);
1429
	mmu_notifier_invalidate_range_end(mm, address, end);
P
Peter Zijlstra 已提交
1430
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1431 1432
}

1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450
/**
 * 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;
1451
	zap_page_range_single(vma, address, size, NULL);
1452 1453 1454 1455
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

1456
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
1457
			spinlock_t **ptl)
1458 1459 1460 1461
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1462
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1463 1464
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
1465
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1466
		}
1467 1468 1469 1470
	}
	return NULL;
}

1471 1472 1473 1474 1475 1476 1477
/*
 * 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
1478 1479
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1480
{
N
Nick Piggin 已提交
1481
	struct mm_struct *mm = vma->vm_mm;
1482
	int retval;
1483
	pte_t *pte;
1484 1485
	spinlock_t *ptl;

1486
	retval = -EINVAL;
1487
	if (PageAnon(page))
1488
		goto out;
1489 1490
	retval = -ENOMEM;
	flush_dcache_page(page);
1491
	pte = get_locked_pte(mm, addr, &ptl);
1492
	if (!pte)
1493
		goto out;
1494 1495 1496 1497 1498 1499
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
1500
	inc_mm_counter_fast(mm, MM_FILEPAGES);
1501 1502 1503 1504
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1505 1506
	pte_unmap_unlock(pte, ptl);
	return retval;
1507 1508 1509 1510 1511 1512
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1513 1514 1515 1516 1517 1518
/**
 * 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
 *
1519 1520 1521 1522 1523 1524
 * 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
1525
 * (see split_page()).
1526 1527 1528 1529 1530 1531 1532 1533
 *
 * 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.
1534 1535 1536 1537 1538
 *
 * 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.
1539
 */
N
Nick Piggin 已提交
1540 1541
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1542 1543 1544 1545 1546
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1547 1548 1549 1550 1551
	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
1552
	return insert_page(vma, addr, page, vma->vm_page_prot);
1553
}
1554
EXPORT_SYMBOL(vm_insert_page);
1555

N
Nick Piggin 已提交
1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574
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);
1575
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1576 1577 1578 1579 1580 1581 1582 1583

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

N
Nick Piggin 已提交
1584 1585 1586 1587 1588 1589
/**
 * 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
 *
1590
 * Similar to vm_insert_page, this allows drivers to insert individual pages
N
Nick Piggin 已提交
1591 1592 1593 1594
 * 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
1595 1596 1597 1598 1599
 *
 * 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
1600 1601
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1602
			unsigned long pfn)
N
Nick Piggin 已提交
1603
{
1604
	int ret;
1605
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1606 1607 1608 1609 1610 1611
	/*
	 * 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
1612 1613 1614 1615 1616
	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
1617

N
Nick Piggin 已提交
1618 1619
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1620
	if (track_pfn_insert(vma, &pgprot, pfn))
1621 1622
		return -EINVAL;

1623
	ret = insert_pfn(vma, addr, pfn, pgprot);
1624 1625

	return ret;
N
Nick Piggin 已提交
1626 1627
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1628

N
Nick Piggin 已提交
1629 1630 1631 1632
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
1633

N
Nick Piggin 已提交
1634 1635
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1636

N
Nick Piggin 已提交
1637 1638 1639 1640
	/*
	 * 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
1641 1642
	 * 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
1643 1644 1645 1646 1647 1648 1649 1650
	 */
	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
1651
}
N
Nick Piggin 已提交
1652
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1653

L
Linus Torvalds 已提交
1654 1655 1656 1657 1658 1659 1660 1661 1662 1663
/*
 * 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
1664
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1665

H
Hugh Dickins 已提交
1666
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1667 1668
	if (!pte)
		return -ENOMEM;
1669
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1670 1671
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1672
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1673 1674
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1675
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1676
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690
	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;
1691
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720
	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;
}

1721 1722 1723 1724 1725 1726 1727 1728 1729 1730
/**
 * 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
1731 1732 1733 1734 1735
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;
1736
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1737 1738 1739 1740 1741 1742 1743 1744
	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).
1745 1746 1747
	 *   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.
1748 1749 1750 1751
	 *   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
1752 1753 1754 1755
	 *
	 * 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".
1756
	 * See vm_normal_page() for details.
L
Linus Torvalds 已提交
1757
	 */
1758 1759 1760
	if (is_cow_mapping(vma->vm_flags)) {
		if (addr != vma->vm_start || end != vma->vm_end)
			return -EINVAL;
L
Linus Torvalds 已提交
1761
		vma->vm_pgoff = pfn;
1762 1763 1764 1765
	}

	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
	if (err)
1766
		return -EINVAL;
L
Linus Torvalds 已提交
1767

1768
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
L
Linus Torvalds 已提交
1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780

	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);
1781 1782

	if (err)
1783
		untrack_pfn(vma, pfn, PAGE_ALIGN(size));
1784

L
Linus Torvalds 已提交
1785 1786 1787 1788
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835
/**
 * 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);

1836 1837 1838 1839 1840 1841
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;
1842
	pgtable_t token;
1843
	spinlock_t *uninitialized_var(ptl);
1844 1845 1846 1847 1848 1849 1850 1851 1852

	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));

1853 1854
	arch_enter_lazy_mmu_mode();

1855
	token = pmd_pgtable(*pmd);
1856 1857

	do {
1858
		err = fn(pte++, token, addr, data);
1859 1860
		if (err)
			break;
1861
	} while (addr += PAGE_SIZE, addr != end);
1862

1863 1864
	arch_leave_lazy_mmu_mode();

1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877
	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
1878 1879
	BUG_ON(pud_huge(*pud));

1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920
	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;
1921
	unsigned long end = addr + size;
1922 1923 1924 1925 1926 1927 1928 1929 1930 1931
	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);
1932

1933 1934 1935 1936
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1937 1938 1939 1940
/*
 * 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
1941
 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
1942 1943
 * must check under lock before unmapping the pte and proceeding
 * (but do_wp_page is only called after already making such a check;
1944
 * and do_anonymous_page can safely check later on).
1945
 */
H
Hugh Dickins 已提交
1946
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1947 1948 1949 1950 1951
				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
1952 1953
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1954
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1955
		spin_unlock(ptl);
1956 1957 1958 1959 1960 1961
	}
#endif
	pte_unmap(page_table);
	return same;
}

1962
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1963
{
1964 1965
	debug_dma_assert_idle(src);

1966 1967 1968 1969 1970 1971 1972
	/*
	 * 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)) {
1973
		void *kaddr = kmap_atomic(dst);
L
Linus Torvalds 已提交
1974 1975 1976 1977 1978 1979 1980 1981 1982
		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))
1983
			clear_page(kaddr);
1984
		kunmap_atomic(kaddr);
1985
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1986 1987
	} else
		copy_user_highpage(dst, src, va, vma);
1988 1989
}

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
/*
 * Notify the address space that the page is about to become writable so that
 * it can prohibit this or wait for the page to get into an appropriate state.
 *
 * We do this without the lock held, so that it can sleep if it needs to.
 */
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
2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035
/*
 * 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.
 *
2036 2037 2038
 * 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
2039
 */
2040 2041
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2042
		spinlock_t *ptl, pte_t orig_pte)
2043
	__releases(ptl)
L
Linus Torvalds 已提交
2044
{
2045
	struct page *old_page, *new_page = NULL;
L
Linus Torvalds 已提交
2046
	pte_t entry;
2047
	int ret = 0;
2048
	int page_mkwrite = 0;
2049
	struct page *dirty_page = NULL;
2050 2051
	unsigned long mmun_start = 0;	/* For mmu_notifiers */
	unsigned long mmun_end = 0;	/* For mmu_notifiers */
2052
	struct mem_cgroup *memcg;
L
Linus Torvalds 已提交
2053

2054
	old_page = vm_normal_page(vma, address, orig_pte);
2055 2056
	if (!old_page) {
		/*
2057 2058
		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
		 * VM_PFNMAP VMA.
2059 2060 2061 2062 2063 2064 2065 2066
		 *
		 * 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;
2067
		goto gotten;
2068
	}
L
Linus Torvalds 已提交
2069

2070
	/*
P
Peter Zijlstra 已提交
2071 2072
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2073
	 */
H
Hugh Dickins 已提交
2074
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085
		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
2086
		}
2087
		if (reuse_swap_page(old_page)) {
2088 2089 2090 2091 2092 2093
			/*
			 * 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);
2094 2095 2096
			unlock_page(old_page);
			goto reuse;
		}
2097
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2098
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2099
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
2100 2101 2102 2103 2104
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
2105
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2106
			int tmp;
2107 2108
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);
2109 2110 2111 2112 2113
			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;
2114
			}
2115 2116 2117 2118 2119 2120 2121 2122
			/*
			 * 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
2123 2124
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
2125
				goto unlock;
N
Nick Piggin 已提交
2126
			}
2127 2128

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2129
		}
2130 2131
		dirty_page = old_page;
		get_page(dirty_page);
2132

2133
reuse:
2134 2135 2136 2137 2138 2139 2140 2141
		/*
		 * 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);

2142 2143 2144
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2145
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2146
			update_mmu_cache(vma, address, page_table);
2147
		pte_unmap_unlock(page_table, ptl);
2148
		ret |= VM_FAULT_WRITE;
2149 2150 2151 2152 2153 2154 2155 2156 2157 2158

		if (!dirty_page)
			return ret;

		/*
		 * Yes, Virginia, this is actually required to prevent a race
		 * with clear_page_dirty_for_io() from clearing the page dirty
		 * bit after it clear all dirty ptes, but before a racing
		 * do_wp_page installs a dirty pte.
		 *
2159
		 * do_shared_fault is protected similarly.
2160 2161 2162
		 */
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
2163
			set_page_dirty_balance(dirty_page);
2164 2165 2166
			/* file_update_time outside page_lock */
			if (vma->vm_file)
				file_update_time(vma->vm_file);
2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184
		}
		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
2185 2186 2187 2188 2189
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2190
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2191
gotten:
2192
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2193 2194

	if (unlikely(anon_vma_prepare(vma)))
2195
		goto oom;
H
Hugh Dickins 已提交
2196

H
Hugh Dickins 已提交
2197
	if (is_zero_pfn(pte_pfn(orig_pte))) {
H
Hugh Dickins 已提交
2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208
		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);

2209
	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg))
2210 2211
		goto oom_free_new;

2212
	mmun_start  = address & PAGE_MASK;
2213
	mmun_end    = mmun_start + PAGE_SIZE;
2214 2215
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);

L
Linus Torvalds 已提交
2216 2217 2218
	/*
	 * Re-check the pte - we dropped the lock
	 */
2219
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2220
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2221 2222
		if (old_page) {
			if (!PageAnon(old_page)) {
2223 2224
				dec_mm_counter_fast(mm, MM_FILEPAGES);
				inc_mm_counter_fast(mm, MM_ANONPAGES);
H
Hugh Dickins 已提交
2225 2226
			}
		} else
2227
			inc_mm_counter_fast(mm, MM_ANONPAGES);
2228
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2229 2230
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2231 2232 2233 2234 2235 2236
		/*
		 * 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.
		 */
2237
		ptep_clear_flush(vma, address, page_table);
N
Nick Piggin 已提交
2238
		page_add_new_anon_rmap(new_page, vma, address);
2239 2240
		mem_cgroup_commit_charge(new_page, memcg, false);
		lru_cache_add_active_or_unevictable(new_page, vma);
2241 2242 2243 2244 2245 2246
		/*
		 * 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);
2247
		update_mmu_cache(vma, address, page_table);
N
Nick Piggin 已提交
2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270
		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.
			 */
2271
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2272 2273
		}

L
Linus Torvalds 已提交
2274 2275
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2276
		ret |= VM_FAULT_WRITE;
2277
	} else
2278
		mem_cgroup_cancel_charge(new_page, memcg);
2279

2280 2281
	if (new_page)
		page_cache_release(new_page);
2282
unlock:
2283
	pte_unmap_unlock(page_table, ptl);
2284
	if (mmun_end > mmun_start)
2285
		mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297
	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
2298
	return ret;
2299
oom_free_new:
2300
	page_cache_release(new_page);
2301
oom:
2302
	if (old_page)
H
Hugh Dickins 已提交
2303
		page_cache_release(old_page);
L
Linus Torvalds 已提交
2304 2305 2306
	return VM_FAULT_OOM;
}

2307
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2308 2309 2310
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
2311
	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
L
Linus Torvalds 已提交
2312 2313
}

2314
static inline void unmap_mapping_range_tree(struct rb_root *root,
L
Linus Torvalds 已提交
2315 2316 2317 2318 2319
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	pgoff_t vba, vea, zba, zea;

2320
	vma_interval_tree_foreach(vma, root,
L
Linus Torvalds 已提交
2321 2322 2323
			details->first_index, details->last_index) {

		vba = vma->vm_pgoff;
2324
		vea = vba + vma_pages(vma) - 1;
L
Linus Torvalds 已提交
2325 2326 2327 2328 2329 2330 2331 2332
		/* 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;

2333
		unmap_mapping_range_vma(vma,
L
Linus Torvalds 已提交
2334 2335
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2336
				details);
L
Linus Torvalds 已提交
2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350
	}
}

static inline void unmap_mapping_range_list(struct list_head *head,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;

	/*
	 * In nonlinear VMAs there is no correspondence between virtual address
	 * offset and file offset.  So we must perform an exhaustive search
	 * across *all* the pages in each nonlinear VMA, not just the pages
	 * whose virtual address lies outside the file truncation point.
	 */
2351
	list_for_each_entry(vma, head, shared.nonlinear) {
L
Linus Torvalds 已提交
2352
		details->nonlinear_vma = vma;
2353
		unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
L
Linus Torvalds 已提交
2354 2355 2356 2357
	}
}

/**
2358
 * 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
2359
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2360 2361
 * @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
2362
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393
 * must keep the partial page.  In contrast, we must get rid of
 * partial pages.
 * @holelen: size of prospective hole in bytes.  This will be rounded
 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
 * end of the file.
 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
 * but 0 when invalidating pagecache, don't throw away private data.
 */
void unmap_mapping_range(struct address_space *mapping,
		loff_t const holebegin, loff_t const holelen, int even_cows)
{
	struct zap_details details;
	pgoff_t hba = holebegin >> PAGE_SHIFT;
	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;

	/* Check for overflow. */
	if (sizeof(holelen) > sizeof(hlen)) {
		long long holeend =
			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
		if (holeend & ~(long long)ULONG_MAX)
			hlen = ULONG_MAX - hba + 1;
	}

	details.check_mapping = even_cows? NULL: mapping;
	details.nonlinear_vma = NULL;
	details.first_index = hba;
	details.last_index = hba + hlen - 1;
	if (details.last_index < details.first_index)
		details.last_index = ULONG_MAX;


2394
	mutex_lock(&mapping->i_mmap_mutex);
2395
	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
L
Linus Torvalds 已提交
2396 2397 2398
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2399
	mutex_unlock(&mapping->i_mmap_mutex);
L
Linus Torvalds 已提交
2400 2401 2402 2403
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
2404 2405
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
2406 2407 2408 2409
 * 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
2410
 */
2411 2412
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2413
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2414
{
2415
	spinlock_t *ptl;
2416
	struct page *page, *swapcache;
2417
	struct mem_cgroup *memcg;
2418
	swp_entry_t entry;
L
Linus Torvalds 已提交
2419
	pte_t pte;
2420
	int locked;
2421
	int exclusive = 0;
N
Nick Piggin 已提交
2422
	int ret = 0;
L
Linus Torvalds 已提交
2423

H
Hugh Dickins 已提交
2424
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2425
		goto out;
2426 2427

	entry = pte_to_swp_entry(orig_pte);
2428 2429 2430 2431 2432 2433 2434
	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
2435
			ret = VM_FAULT_SIGBUS;
2436
		}
2437 2438
		goto out;
	}
2439
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2440 2441
	page = lookup_swap_cache(entry);
	if (!page) {
2442 2443
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2444 2445
		if (!page) {
			/*
2446 2447
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2448
			 */
2449
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2450 2451
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2452
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2453
			goto unlock;
L
Linus Torvalds 已提交
2454 2455 2456 2457
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2458
		count_vm_event(PGMAJFAULT);
2459
		mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2460
	} else if (PageHWPoison(page)) {
2461 2462 2463 2464
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2465 2466
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2467
		swapcache = page;
2468
		goto out_release;
L
Linus Torvalds 已提交
2469 2470
	}

2471
	swapcache = page;
2472
	locked = lock_page_or_retry(page, mm, flags);
R
Rik van Riel 已提交
2473

2474
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2475 2476 2477 2478
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2479

A
Andrea Arcangeli 已提交
2480
	/*
2481 2482 2483 2484
	 * 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
2485
	 */
2486
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2487 2488
		goto out_page;

2489 2490 2491 2492 2493
	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
2494 2495
	}

2496
	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg)) {
2497
		ret = VM_FAULT_OOM;
2498
		goto out_page;
2499 2500
	}

L
Linus Torvalds 已提交
2501
	/*
2502
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2503
	 */
2504
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2505
	if (unlikely(!pte_same(*page_table, orig_pte)))
2506 2507 2508 2509 2510
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2511 2512
	}

2513 2514 2515 2516 2517 2518 2519 2520 2521
	/*
	 * 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
2522

2523
	inc_mm_counter_fast(mm, MM_ANONPAGES);
K
KAMEZAWA Hiroyuki 已提交
2524
	dec_mm_counter_fast(mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
2525
	pte = mk_pte(page, vma->vm_page_prot);
2526
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2527
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2528
		flags &= ~FAULT_FLAG_WRITE;
2529
		ret |= VM_FAULT_WRITE;
2530
		exclusive = 1;
L
Linus Torvalds 已提交
2531 2532
	}
	flush_icache_page(vma, page);
2533 2534
	if (pte_swp_soft_dirty(orig_pte))
		pte = pte_mksoft_dirty(pte);
L
Linus Torvalds 已提交
2535
	set_pte_at(mm, address, page_table, pte);
2536
	if (page == swapcache) {
2537
		do_page_add_anon_rmap(page, vma, address, exclusive);
2538 2539
		mem_cgroup_commit_charge(page, memcg, true);
	} else { /* ksm created a completely new copy */
2540
		page_add_new_anon_rmap(page, vma, address);
2541 2542 2543
		mem_cgroup_commit_charge(page, memcg, false);
		lru_cache_add_active_or_unevictable(page, vma);
	}
L
Linus Torvalds 已提交
2544

2545
	swap_free(entry);
N
Nick Piggin 已提交
2546
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2547
		try_to_free_swap(page);
2548
	unlock_page(page);
2549
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560
		/*
		 * 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);
	}
2561

2562
	if (flags & FAULT_FLAG_WRITE) {
2563 2564 2565
		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
2566 2567 2568 2569
		goto out;
	}

	/* No need to invalidate - it was non-present before */
2570
	update_mmu_cache(vma, address, page_table);
2571
unlock:
2572
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2573 2574
out:
	return ret;
2575
out_nomap:
2576
	mem_cgroup_cancel_charge(page, memcg);
2577
	pte_unmap_unlock(page_table, ptl);
2578
out_page:
2579
	unlock_page(page);
2580
out_release:
2581
	page_cache_release(page);
2582
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2583 2584 2585
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
2586
	return ret;
L
Linus Torvalds 已提交
2587 2588
}

2589
/*
2590 2591
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2592 2593 2594 2595 2596 2597
 * 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) {
2598 2599 2600 2601 2602 2603 2604 2605 2606 2607
		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;
2608

2609
		expand_downwards(vma, address - PAGE_SIZE);
2610
	}
2611 2612 2613 2614 2615 2616 2617 2618 2619
	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
		struct vm_area_struct *next = vma->vm_next;

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

		expand_upwards(vma, address + PAGE_SIZE);
	}
2620 2621 2622
	return 0;
}

L
Linus Torvalds 已提交
2623
/*
2624 2625 2626
 * 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
2627
 */
2628 2629
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2630
		unsigned int flags)
L
Linus Torvalds 已提交
2631
{
2632
	struct mem_cgroup *memcg;
2633 2634
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2635 2636
	pte_t entry;

2637 2638 2639 2640
	pte_unmap(page_table);

	/* Check if we need to add a guard page to the stack */
	if (check_stack_guard_page(vma, address) < 0)
2641 2642
		return VM_FAULT_SIGBUS;

2643
	/* Use the zero-page for reads */
H
Hugh Dickins 已提交
2644 2645 2646
	if (!(flags & FAULT_FLAG_WRITE)) {
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
2647
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2648 2649 2650 2651 2652
		if (!pte_none(*page_table))
			goto unlock;
		goto setpte;
	}

N
Nick Piggin 已提交
2653 2654 2655 2656 2657 2658
	/* 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;
2659 2660 2661 2662 2663
	/*
	 * 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
2664
	__SetPageUptodate(page);
2665

2666
	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg))
2667 2668
		goto oom_free_page;

N
Nick Piggin 已提交
2669
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
2670 2671
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
2672

N
Nick Piggin 已提交
2673
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2674
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
2675
		goto release;
H
Hugh Dickins 已提交
2676

2677
	inc_mm_counter_fast(mm, MM_ANONPAGES);
N
Nick Piggin 已提交
2678
	page_add_new_anon_rmap(page, vma, address);
2679 2680
	mem_cgroup_commit_charge(page, memcg, false);
	lru_cache_add_active_or_unevictable(page, vma);
H
Hugh Dickins 已提交
2681
setpte:
2682
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2683 2684

	/* No need to invalidate - it was non-present before */
2685
	update_mmu_cache(vma, address, page_table);
2686
unlock:
2687
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2688
	return 0;
2689
release:
2690
	mem_cgroup_cancel_charge(page, memcg);
2691 2692
	page_cache_release(page);
	goto unlock;
2693
oom_free_page:
2694
	page_cache_release(page);
2695
oom:
L
Linus Torvalds 已提交
2696 2697 2698
	return VM_FAULT_OOM;
}

2699 2700 2701 2702 2703
/*
 * 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().
 */
2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734
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;
}

2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750
/**
 * 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,
2751 2752 2753 2754 2755 2756 2757 2758 2759
		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);
	else if (pte_file(*pte) && pte_file_soft_dirty(*pte))
2760
		entry = pte_mksoft_dirty(entry);
2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773
	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);
}

2774 2775
static unsigned long fault_around_bytes __read_mostly =
	rounddown_pow_of_two(65536);
2776 2777 2778

#ifdef CONFIG_DEBUG_FS
static int fault_around_bytes_get(void *data, u64 *val)
2779
{
2780
	*val = fault_around_bytes;
2781 2782 2783
	return 0;
}

2784 2785 2786 2787 2788
/*
 * 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.
 */
2789
static int fault_around_bytes_set(void *data, u64 val)
2790
{
2791
	if (val / PAGE_SIZE > PTRS_PER_PTE)
2792
		return -EINVAL;
2793 2794 2795 2796
	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 */
2797 2798
	return 0;
}
2799 2800
DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
		fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
2801 2802 2803 2804 2805

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

2806 2807
	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
			&fault_around_bytes_fops);
2808
	if (!ret)
2809
		pr_warn("Failed to create fault_around_bytes in debugfs");
2810 2811 2812 2813
	return 0;
}
late_initcall(fault_around_debugfs);
#endif
2814

2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837
/*
 * 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.
 */
2838 2839 2840
static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pgoff_t pgoff, unsigned int flags)
{
2841
	unsigned long start_addr, nr_pages, mask;
2842 2843 2844 2845
	pgoff_t max_pgoff;
	struct vm_fault vmf;
	int off;

2846 2847 2848 2849
	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);
2850 2851 2852 2853 2854 2855
	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
2856
	 *  or fault_around_pages() from pgoff, depending what is nearest.
2857 2858 2859 2860
	 */
	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,
2861
			pgoff + nr_pages - 1);
2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880

	/* 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);
}

2881 2882 2883 2884 2885 2886
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;
2887
	pte_t *pte;
2888 2889 2890 2891 2892 2893 2894
	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).
	 */
2895
	if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&
2896
	    fault_around_bytes >> PAGE_SHIFT > 1) {
2897 2898 2899 2900 2901 2902
		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);
	}
2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914

	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;
	}
2915
	do_set_pte(vma, address, fault_page, pte, false, false);
2916
	unlock_page(fault_page);
2917 2918
unlock_out:
	pte_unmap_unlock(pte, ptl);
2919 2920 2921
	return ret;
}

2922 2923 2924 2925 2926
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;
2927
	struct mem_cgroup *memcg;
2928
	spinlock_t *ptl;
2929
	pte_t *pte;
2930 2931 2932 2933 2934 2935 2936 2937 2938
	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;

2939
	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg)) {
2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957
		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;
	}
2958
	do_set_pte(vma, address, new_page, pte, true, true);
2959 2960
	mem_cgroup_commit_charge(new_page, memcg, false);
	lru_cache_add_active_or_unevictable(new_page, vma);
2961 2962 2963 2964 2965
	pte_unmap_unlock(pte, ptl);
	unlock_page(fault_page);
	page_cache_release(fault_page);
	return ret;
uncharge_out:
2966
	mem_cgroup_cancel_charge(new_page, memcg);
2967 2968 2969 2970
	page_cache_release(new_page);
	return ret;
}

2971
static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2972
		unsigned long address, pmd_t *pmd,
2973
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2974
{
2975 2976
	struct page *fault_page;
	struct address_space *mapping;
2977
	spinlock_t *ptl;
2978
	pte_t *pte;
2979 2980
	int dirtied = 0;
	int ret, tmp;
2981

2982 2983
	ret = __do_fault(vma, address, pgoff, flags, &fault_page);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
2984
		return ret;
L
Linus Torvalds 已提交
2985 2986

	/*
2987 2988
	 * Check if the backing address space wants to know that the page is
	 * about to become writable
L
Linus Torvalds 已提交
2989
	 */
2990 2991 2992 2993 2994
	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)))) {
2995
			page_cache_release(fault_page);
2996
			return tmp;
2997
		}
2998 2999
	}

3000 3001 3002 3003 3004 3005
	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
3006
	}
3007
	do_set_pte(vma, address, fault_page, pte, true, false);
3008
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3009

3010 3011 3012 3013 3014 3015 3016 3017 3018 3019
	if (set_page_dirty(fault_page))
		dirtied = 1;
	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);
3020
	}
3021

3022 3023 3024
	/* 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
3025

3026
	return ret;
3027
}
3028

3029 3030 3031 3032 3033 3034
/*
 * 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().
 */
3035 3036
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3037
		unsigned int flags, pte_t orig_pte)
3038 3039
{
	pgoff_t pgoff = (((address & PAGE_MASK)
3040
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3041

3042
	pte_unmap(page_table);
3043 3044 3045
	if (!(flags & FAULT_FLAG_WRITE))
		return do_read_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3046 3047 3048
	if (!(vma->vm_flags & VM_SHARED))
		return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3049
	return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3050 3051
}

L
Linus Torvalds 已提交
3052 3053 3054 3055
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
3056 3057 3058
 *
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
3059 3060 3061
 * 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
3062
 */
N
Nick Piggin 已提交
3063
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3064
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3065
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3066
{
3067
	pgoff_t pgoff;
L
Linus Torvalds 已提交
3068

3069 3070
	flags |= FAULT_FLAG_NONLINEAR;

H
Hugh Dickins 已提交
3071
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
3072
		return 0;
L
Linus Torvalds 已提交
3073

3074
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3075 3076 3077
		/*
		 * Page table corrupted: show pte and kill process.
		 */
3078
		print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
3079
		return VM_FAULT_SIGBUS;
3080 3081 3082
	}

	pgoff = pte_to_pgoff(orig_pte);
3083 3084 3085
	if (!(flags & FAULT_FLAG_WRITE))
		return do_read_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3086 3087 3088
	if (!(vma->vm_flags & VM_SHARED))
		return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3089
	return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
3090 3091
}

3092
static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3093 3094
				unsigned long addr, int page_nid,
				int *flags)
3095 3096 3097 3098
{
	get_page(page);

	count_vm_numa_event(NUMA_HINT_FAULTS);
3099
	if (page_nid == numa_node_id()) {
3100
		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3101 3102
		*flags |= TNF_FAULT_LOCAL;
	}
3103 3104 3105 3106

	return mpol_misplaced(page, vma, addr);
}

3107
static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3108 3109
		   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
{
3110
	struct page *page = NULL;
3111
	spinlock_t *ptl;
3112
	int page_nid = -1;
3113
	int last_cpupid;
3114
	int target_nid;
3115
	bool migrated = false;
3116
	int flags = 0;
3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128

	/*
	* 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);
3129 3130 3131 3132 3133
	if (unlikely(!pte_same(*ptep, pte))) {
		pte_unmap_unlock(ptep, ptl);
		goto out;
	}

3134 3135 3136 3137 3138 3139 3140 3141 3142
	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;
	}
3143
	BUG_ON(is_zero_pfn(page_to_pfn(page)));
3144

3145 3146 3147 3148 3149 3150 3151 3152
	/*
	 * 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;

3153 3154 3155 3156 3157 3158 3159
	/*
	 * 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;

3160
	last_cpupid = page_cpupid_last(page);
3161
	page_nid = page_to_nid(page);
3162
	target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3163
	pte_unmap_unlock(ptep, ptl);
3164 3165 3166 3167 3168 3169
	if (target_nid == -1) {
		put_page(page);
		goto out;
	}

	/* Migrate to the requested node */
3170
	migrated = migrate_misplaced_page(page, vma, target_nid);
3171
	if (migrated) {
3172
		page_nid = target_nid;
3173 3174
		flags |= TNF_MIGRATED;
	}
3175 3176

out:
3177
	if (page_nid != -1)
3178
		task_numa_fault(last_cpupid, page_nid, 1, flags);
3179 3180 3181
	return 0;
}

L
Linus Torvalds 已提交
3182 3183 3184 3185 3186 3187 3188 3189 3190
/*
 * 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
3191 3192
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
3193 3194 3195 3196
 * 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
3197
 */
3198
static int handle_pte_fault(struct mm_struct *mm,
3199 3200
		     struct vm_area_struct *vma, unsigned long address,
		     pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
3201 3202
{
	pte_t entry;
3203
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3204

3205
	entry = ACCESS_ONCE(*pte);
L
Linus Torvalds 已提交
3206
	if (!pte_present(entry)) {
3207
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
3208
			if (vma->vm_ops) {
N
Nick Piggin 已提交
3209
				if (likely(vma->vm_ops->fault))
3210
					return do_linear_fault(mm, vma, address,
3211
						pte, pmd, flags, entry);
J
Jes Sorensen 已提交
3212 3213
			}
			return do_anonymous_page(mm, vma, address,
3214
						 pte, pmd, flags);
3215
		}
L
Linus Torvalds 已提交
3216
		if (pte_file(entry))
N
Nick Piggin 已提交
3217
			return do_nonlinear_fault(mm, vma, address,
3218
					pte, pmd, flags, entry);
3219
		return do_swap_page(mm, vma, address,
3220
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
3221 3222
	}

3223 3224 3225
	if (pte_numa(entry))
		return do_numa_page(mm, vma, address, entry, pte, pmd);

H
Hugh Dickins 已提交
3226
	ptl = pte_lockptr(mm, pmd);
3227 3228 3229
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
3230
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3231
		if (!pte_write(entry))
3232 3233
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
3234 3235 3236
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
3237
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3238
		update_mmu_cache(vma, address, pte);
3239 3240 3241 3242 3243 3244 3245
	} 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.
		 */
3246
		if (flags & FAULT_FLAG_WRITE)
3247
			flush_tlb_fix_spurious_fault(vma, address);
3248
	}
3249 3250
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3251
	return 0;
L
Linus Torvalds 已提交
3252 3253 3254 3255
}

/*
 * By the time we get here, we already hold the mm semaphore
3256 3257 3258
 *
 * 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
3259
 */
3260 3261
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
3262 3263 3264 3265 3266 3267
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

3268
	if (unlikely(is_vm_hugetlb_page(vma)))
3269
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3270 3271 3272 3273

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3274
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3275 3276
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3277
		return VM_FAULT_OOM;
3278
	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3279
		int ret = VM_FAULT_FALLBACK;
3280
		if (!vma->vm_ops)
3281 3282 3283 3284
			ret = do_huge_pmd_anonymous_page(mm, vma, address,
					pmd, flags);
		if (!(ret & VM_FAULT_FALLBACK))
			return ret;
3285 3286
	} else {
		pmd_t orig_pmd = *pmd;
3287 3288
		int ret;

3289 3290
		barrier();
		if (pmd_trans_huge(orig_pmd)) {
3291 3292
			unsigned int dirty = flags & FAULT_FLAG_WRITE;

3293 3294 3295 3296 3297 3298 3299 3300
			/*
			 * 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;

3301
			if (pmd_numa(orig_pmd))
3302
				return do_huge_pmd_numa_page(mm, vma, address,
3303 3304
							     orig_pmd, pmd);

3305
			if (dirty && !pmd_write(orig_pmd)) {
3306 3307
				ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
							  orig_pmd);
3308 3309
				if (!(ret & VM_FAULT_FALLBACK))
					return ret;
3310 3311 3312
			} else {
				huge_pmd_set_accessed(mm, vma, address, pmd,
						      orig_pmd, dirty);
3313
				return 0;
3314
			}
3315 3316 3317 3318 3319 3320 3321 3322
		}
	}

	/*
	 * 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.
	 */
3323 3324
	if (unlikely(pmd_none(*pmd)) &&
	    unlikely(__pte_alloc(mm, vma, pmd, address)))
H
Hugh Dickins 已提交
3325
		return VM_FAULT_OOM;
3326 3327 3328 3329 3330 3331 3332 3333 3334 3335
	/* 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
3336

3337
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3338 3339
}

3340 3341 3342 3343 3344 3345
/*
 * 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().
 */
3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363
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)
3364
		mem_cgroup_oom_enable();
3365 3366 3367

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

3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378
	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);
	}
3379

3380 3381 3382
	return ret;
}

L
Linus Torvalds 已提交
3383 3384 3385
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3386
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3387
 */
3388
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3389
{
H
Hugh Dickins 已提交
3390 3391
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3392
		return -ENOMEM;
L
Linus Torvalds 已提交
3393

3394 3395
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3396
	spin_lock(&mm->page_table_lock);
3397
	if (pgd_present(*pgd))		/* Another has populated it */
3398
		pud_free(mm, new);
3399 3400
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3401
	spin_unlock(&mm->page_table_lock);
3402
	return 0;
L
Linus Torvalds 已提交
3403 3404 3405 3406 3407 3408
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3409
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3410
 */
3411
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3412
{
H
Hugh Dickins 已提交
3413 3414
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3415
		return -ENOMEM;
L
Linus Torvalds 已提交
3416

3417 3418
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3419
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3420
#ifndef __ARCH_HAS_4LEVEL_HACK
3421
	if (pud_present(*pud))		/* Another has populated it */
3422
		pmd_free(mm, new);
3423 3424
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3425
#else
3426
	if (pgd_present(*pud))		/* Another has populated it */
3427
		pmd_free(mm, new);
3428 3429
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3430
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3431
	spin_unlock(&mm->page_table_lock);
3432
	return 0;
3433
}
L
Linus Torvalds 已提交
3434 3435
#endif /* __PAGETABLE_PMD_FOLDED */

3436
static int __follow_pte(struct mm_struct *mm, unsigned long address,
J
Johannes Weiner 已提交
3437 3438 3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452
		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);
3453
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3454 3455 3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473
	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;
}

3474 3475 3476 3477 3478 3479 3480 3481 3482 3483 3484
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
3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512 3513
/**
 * 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);

3514
#ifdef CONFIG_HAVE_IOREMAP_PROT
3515 3516 3517
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3518
{
3519
	int ret = -EINVAL;
3520 3521 3522
	pte_t *ptep, pte;
	spinlock_t *ptl;

3523 3524
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3525

3526
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3527
		goto out;
3528
	pte = *ptep;
3529

3530 3531 3532 3533
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3534
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3535

3536
	ret = 0;
3537 3538 3539
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3540
	return ret;
3541 3542 3543 3544 3545 3546 3547
}

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
3548
	void __iomem *maddr;
3549 3550
	int offset = addr & (PAGE_SIZE-1);

3551
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3552 3553 3554 3555 3556 3557 3558 3559 3560 3561 3562
		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;
}
3563
EXPORT_SYMBOL_GPL(generic_access_phys);
3564 3565
#endif

3566
/*
3567 3568
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
3569
 */
3570 3571
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long addr, void *buf, int len, int write)
3572 3573 3574 3575 3576
{
	struct vm_area_struct *vma;
	void *old_buf = buf;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3577
	/* ignore errors, just check how much was successfully transferred */
3578 3579 3580
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3581
		struct page *page = NULL;
3582 3583 3584

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3585
		if (ret <= 0) {
3586 3587 3588
#ifndef CONFIG_HAVE_IOREMAP_PROT
			break;
#else
3589 3590 3591 3592 3593
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
			vma = find_vma(mm, addr);
3594
			if (!vma || vma->vm_start > addr)
3595 3596 3597 3598 3599 3600 3601
				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;
3602
#endif
3603
		} else {
3604 3605 3606 3607 3608 3609 3610 3611 3612 3613 3614 3615 3616 3617 3618 3619
			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);
3620 3621 3622 3623 3624 3625 3626 3627 3628
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
3629

S
Stephen Wilson 已提交
3630
/**
3631
 * access_remote_vm - access another process' address space
S
Stephen Wilson 已提交
3632 3633 3634 3635 3636 3637 3638 3639 3640 3641 3642 3643 3644 3645
 * @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);
}

3646 3647 3648 3649 3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660 3661 3662 3663 3664 3665 3666
/*
 * 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;
}

3667 3668 3669 3670 3671 3672 3673 3674
/*
 * 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;

3675 3676 3677 3678 3679 3680 3681
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3682 3683 3684 3685 3686 3687
	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
3688
			char *p;
3689

3690
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3691 3692
			if (IS_ERR(p))
				p = "?";
A
Andy Shevchenko 已提交
3693
			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3694 3695 3696 3697 3698
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
3699
	up_read(&mm->mmap_sem);
3700
}
3701

3702
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3703 3704
void might_fault(void)
{
3705 3706 3707 3708 3709 3710 3711 3712 3713
	/*
	 * 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;

3714 3715 3716 3717 3718
	/*
	 * 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.
	 */
3719 3720 3721 3722 3723 3724
	if (in_atomic())
		return;

	__might_sleep(__FILE__, __LINE__, 0);

	if (current->mm)
3725 3726 3727 3728
		might_lock_read(&current->mm->mmap_sem);
}
EXPORT_SYMBOL(might_fault);
#endif
A
Andrea Arcangeli 已提交
3729 3730 3731 3732 3733 3734 3735 3736 3737 3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759 3760 3761 3762 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780 3781 3782 3783 3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796 3797 3798 3799

#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 */
3800

3801
#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
3802 3803 3804 3805 3806 3807 3808 3809 3810

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);
}

3811
bool ptlock_alloc(struct page *page)
3812 3813 3814
{
	spinlock_t *ptl;

3815
	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
3816 3817
	if (!ptl)
		return false;
3818
	page->ptl = ptl;
3819 3820 3821
	return true;
}

3822
void ptlock_free(struct page *page)
3823
{
3824
	kmem_cache_free(page_ptl_cachep, page->ptl);
3825 3826
}
#endif