memory.c 102.8 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

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

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

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

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

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

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#include "internal.h"

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

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#ifndef CONFIG_NEED_MULTIPLE_NODES
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/* use the per-pgdat data instead for discontigmem - mbligh */
unsigned long max_mapnr;
struct page *mem_map;

EXPORT_SYMBOL(max_mapnr);
EXPORT_SYMBOL(mem_map);
#endif

/*
 * A number of key systems in x86 including ioremap() rely on the assumption
 * that high_memory defines the upper bound on direct map memory, then end
 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
 * and ZONE_HIGHMEM.
 */
void * high_memory;

EXPORT_SYMBOL(high_memory);

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

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unsigned long zero_pfn __read_mostly;
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unsigned long highest_memmap_pfn __read_mostly;
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EXPORT_SYMBOL(zero_pfn);

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

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

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

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

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

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

static void check_sync_rss_stat(struct task_struct *task)
{
}

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#endif /* SPLIT_RSS_COUNTING */

#ifdef HAVE_GENERIC_MMU_GATHER

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

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

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

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

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

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

	return 1;
}

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

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	/* Is it from 0 to ~0? */
	tlb->fullmm     = !(start | (end+1));
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	tlb->need_flush_all = 0;
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	tlb->local.next = NULL;
	tlb->local.nr   = 0;
	tlb->local.max  = ARRAY_SIZE(tlb->__pages);
	tlb->active     = &tlb->local;
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	tlb->batch_count = 0;
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#ifdef CONFIG_HAVE_RCU_TABLE_FREE
	tlb->batch = NULL;
#endif
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	__tlb_reset_range(tlb);
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}

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

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

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

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

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

	tlb_flush_mmu(tlb);

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

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

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

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

#endif /* HAVE_GENERIC_MMU_GATHER */

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#ifdef CONFIG_HAVE_RCU_TABLE_FREE

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

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

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

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

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

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

	free_page((unsigned long)batch);
}

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

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

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

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

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

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

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

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

	pmd = pmd_offset(pud, start);
	pud_clear(pud);
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	pmd_free_tlb(tlb, pmd, start);
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	mm_dec_nr_pmds(tlb->mm);
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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);
620
	return 0;
L
Linus Torvalds 已提交
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
		"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
	 */
693 694 695 696 697
	pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
		 vma->vm_file,
		 vma->vm_ops ? vma->vm_ops->fault : NULL,
		 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
		 mapping ? mapping->a_ops->readpage : NULL);
N
Nick Piggin 已提交
698
	dump_stack();
699
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
N
Nick Piggin 已提交
700 701
}

H
Hugh Dickins 已提交
702
/*
N
Nick Piggin 已提交
703
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
704
 *
N
Nick Piggin 已提交
705 706 707
 * "Special" mappings do not wish to be associated with a "struct page" (either
 * it doesn't exist, or it exists but they don't want to touch it). In this
 * case, NULL is returned here. "Normal" mappings do have a struct page.
J
Jared Hulbert 已提交
708
 *
N
Nick Piggin 已提交
709 710 711 712 713 714 715 716
 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 * pte bit, in which case this function is trivial. Secondly, an architecture
 * may not have a spare pte bit, which requires a more complicated scheme,
 * described below.
 *
 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 * special mapping (even if there are underlying and valid "struct pages").
 * COWed pages of a VM_PFNMAP are always normal.
717
 *
J
Jared Hulbert 已提交
718 719
 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
N
Nick Piggin 已提交
720 721
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
722 723 724
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
725 726 727 728 729 730
 * And for normal mappings this is false.
 *
 * This restricts such mappings to be a linear translation from virtual address
 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 * as the vma is not a COW mapping; in that case, we know that all ptes are
 * special (because none can have been COWed).
J
Jared Hulbert 已提交
731 732
 *
 *
N
Nick Piggin 已提交
733
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
734 735 736 737 738 739 740 741 742
 *
 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 * page" backing, however the difference is that _all_ pages with a struct
 * page (that is, those where pfn_valid is true) are refcounted and considered
 * normal pages by the VM. The disadvantage is that pages are refcounted
 * (which can be slower and simply not an option for some PFNMAP users). The
 * advantage is that we don't have to follow the strict linearity rule of
 * PFNMAP mappings in order to support COWable mappings.
 *
H
Hugh Dickins 已提交
743
 */
N
Nick Piggin 已提交
744 745 746 747 748 749 750
#ifdef __HAVE_ARCH_PTE_SPECIAL
# define HAVE_PTE_SPECIAL 1
#else
# define HAVE_PTE_SPECIAL 0
#endif
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
				pte_t pte)
H
Hugh Dickins 已提交
751
{
752
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
753 754

	if (HAVE_PTE_SPECIAL) {
755
		if (likely(!pte_special(pte)))
756
			goto check_pfn;
757 758
		if (vma->vm_ops && vma->vm_ops->find_special_page)
			return vma->vm_ops->find_special_page(vma, addr);
H
Hugh Dickins 已提交
759 760
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
761
		if (!is_zero_pfn(pfn))
762
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
763 764 765 766 767
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
768 769 770 771 772 773
	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
774 775
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
776 777 778 779 780
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
781 782
	}

783 784
	if (is_zero_pfn(pfn))
		return NULL;
785 786 787 788 789
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
790 791

	/*
N
Nick Piggin 已提交
792 793
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
794
	 */
J
Jared Hulbert 已提交
795
out:
796
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
797 798
}

L
Linus Torvalds 已提交
799 800 801 802 803 804
/*
 * 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
805
static inline unsigned long
L
Linus Torvalds 已提交
806
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
807
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
808
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
809
{
N
Nick Piggin 已提交
810
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
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))) {
816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849
		swp_entry_t entry = pte_to_swp_entry(pte);

		if (likely(!non_swap_entry(entry))) {
			if (swap_duplicate(entry) < 0)
				return entry.val;

			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
							&src_mm->mmlist);
				spin_unlock(&mmlist_lock);
			}
			rss[MM_SWAPENTS]++;
		} 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);
				if (pte_swp_soft_dirty(*src_pte))
					pte = pte_swp_mksoft_dirty(pte);
				set_pte_at(src_mm, addr, src_pte, pte);
850
			}
L
Linus Torvalds 已提交
851
		}
852
		goto out_set_pte;
L
Linus Torvalds 已提交
853 854 855 856 857 858
	}

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

	/*
	 * If it's a shared mapping, mark it clean in
	 * the child
	 */
	if (vm_flags & VM_SHARED)
		pte = pte_mkclean(pte);
	pte = pte_mkold(pte);
871 872 873 874

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

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

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

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

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

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

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

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962
	if (addr != end)
		goto again;
	return 0;
}

static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pmd_t *src_pmd, *dst_pmd;
	unsigned long next;

	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
	if (!dst_pmd)
		return -ENOMEM;
	src_pmd = pmd_offset(src_pud, addr);
	do {
		next = pmd_addr_end(addr, end);
963 964
		if (pmd_trans_huge(*src_pmd)) {
			int err;
965
			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
966 967 968 969 970 971 972 973
			err = copy_huge_pmd(dst_mm, src_mm,
					    dst_pmd, src_pmd, addr, vma);
			if (err == -ENOMEM)
				return -ENOMEM;
			if (!err)
				continue;
			/* fall through */
		}
L
Linus Torvalds 已提交
974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011
		if (pmd_none_or_clear_bad(src_pmd))
			continue;
		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
	return 0;
}

static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pud_t *src_pud, *dst_pud;
	unsigned long next;

	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
	if (!dst_pud)
		return -ENOMEM;
	src_pud = pud_offset(src_pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(src_pud))
			continue;
		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pud++, src_pud++, addr = next, addr != end);
	return 0;
}

int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		struct vm_area_struct *vma)
{
	pgd_t *src_pgd, *dst_pgd;
	unsigned long next;
	unsigned long addr = vma->vm_start;
	unsigned long end = vma->vm_end;
1012 1013 1014
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	bool is_cow;
A
Andrea Arcangeli 已提交
1015
	int ret;
L
Linus Torvalds 已提交
1016

1017 1018 1019 1020 1021 1022
	/*
	 * Don't copy ptes where a page fault will fill them correctly.
	 * Fork becomes much lighter when there are big shared or private
	 * readonly mappings. The tradeoff is that copy_page_range is more
	 * efficient than faulting.
	 */
1023 1024 1025
	if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
			!vma->anon_vma)
		return 0;
1026

L
Linus Torvalds 已提交
1027 1028 1029
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

1030
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1031 1032 1033 1034
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
1035
		ret = track_pfn_copy(vma);
1036 1037 1038 1039
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
1040 1041 1042 1043 1044 1045
	/*
	 * 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.
	 */
1046 1047 1048 1049 1050 1051
	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
1052 1053

	ret = 0;
L
Linus Torvalds 已提交
1054 1055 1056 1057 1058 1059
	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
1060 1061 1062 1063 1064
		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
1065
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1066

1067 1068
	if (is_cow)
		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
A
Andrea Arcangeli 已提交
1069
	return ret;
L
Linus Torvalds 已提交
1070 1071
}

1072
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1073
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
1074
				unsigned long addr, unsigned long end,
1075
				struct zap_details *details)
L
Linus Torvalds 已提交
1076
{
N
Nick Piggin 已提交
1077
	struct mm_struct *mm = tlb->mm;
P
Peter Zijlstra 已提交
1078
	int force_flush = 0;
K
KAMEZAWA Hiroyuki 已提交
1079
	int rss[NR_MM_COUNTERS];
1080
	spinlock_t *ptl;
1081
	pte_t *start_pte;
1082
	pte_t *pte;
1083
	swp_entry_t entry;
K
KAMEZAWA Hiroyuki 已提交
1084

P
Peter Zijlstra 已提交
1085
again:
1086
	init_rss_vec(rss);
1087 1088
	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	pte = start_pte;
1089
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1090 1091
	do {
		pte_t ptent = *pte;
1092
		if (pte_none(ptent)) {
L
Linus Torvalds 已提交
1093
			continue;
1094
		}
1095

L
Linus Torvalds 已提交
1096
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
1097
			struct page *page;
1098

1099
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
1100 1101 1102 1103 1104 1105 1106 1107 1108 1109
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
				    details->check_mapping != page->mapping)
					continue;
			}
N
Nick Piggin 已提交
1110
			ptent = ptep_get_and_clear_full(mm, addr, pte,
1111
							tlb->fullmm);
L
Linus Torvalds 已提交
1112 1113 1114 1115
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (PageAnon(page))
K
KAMEZAWA Hiroyuki 已提交
1116
				rss[MM_ANONPAGES]--;
1117
			else {
1118 1119
				if (pte_dirty(ptent)) {
					force_flush = 1;
1120
					set_page_dirty(page);
1121
				}
1122
				if (pte_young(ptent) &&
1123
				    likely(!(vma->vm_flags & VM_SEQ_READ)))
1124
					mark_page_accessed(page);
K
KAMEZAWA Hiroyuki 已提交
1125
				rss[MM_FILEPAGES]--;
1126
			}
1127
			page_remove_rmap(page);
1128 1129
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
1130 1131
			if (unlikely(!__tlb_remove_page(tlb, page))) {
				force_flush = 1;
1132
				addr += PAGE_SIZE;
P
Peter Zijlstra 已提交
1133
				break;
1134
			}
L
Linus Torvalds 已提交
1135 1136
			continue;
		}
1137
		/* If details->check_mapping, we leave swap entries. */
L
Linus Torvalds 已提交
1138 1139
		if (unlikely(details))
			continue;
K
KAMEZAWA Hiroyuki 已提交
1140

1141 1142 1143 1144 1145
		entry = pte_to_swp_entry(ptent);
		if (!non_swap_entry(entry))
			rss[MM_SWAPENTS]--;
		else if (is_migration_entry(entry)) {
			struct page *page;
1146

1147
			page = migration_entry_to_page(entry);
1148

1149 1150 1151 1152
			if (PageAnon(page))
				rss[MM_ANONPAGES]--;
			else
				rss[MM_FILEPAGES]--;
K
KAMEZAWA Hiroyuki 已提交
1153
		}
1154 1155
		if (unlikely(!free_swap_and_cache(entry)))
			print_bad_pte(vma, addr, ptent, NULL);
1156
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1157
	} while (pte++, addr += PAGE_SIZE, addr != end);
1158

K
KAMEZAWA Hiroyuki 已提交
1159
	add_mm_rss_vec(mm, rss);
1160
	arch_leave_lazy_mmu_mode();
1161

1162
	/* Do the actual TLB flush before dropping ptl */
1163
	if (force_flush)
1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175
		tlb_flush_mmu_tlbonly(tlb);
	pte_unmap_unlock(start_pte, ptl);

	/*
	 * If we forced a TLB flush (either due to running out of
	 * batch buffers or because we needed to flush dirty TLB
	 * entries before releasing the ptl), free the batched
	 * memory too. Restart if we didn't do everything.
	 */
	if (force_flush) {
		force_flush = 0;
		tlb_flush_mmu_free(tlb);
1176 1177

		if (addr != end)
P
Peter Zijlstra 已提交
1178 1179 1180
			goto again;
	}

1181
	return addr;
L
Linus Torvalds 已提交
1182 1183
}

1184
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1185
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
1186
				unsigned long addr, unsigned long end,
1187
				struct zap_details *details)
L
Linus Torvalds 已提交
1188 1189 1190 1191 1192 1193 1194
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1195
		if (pmd_trans_huge(*pmd)) {
1196
			if (next - addr != HPAGE_PMD_SIZE) {
1197 1198 1199 1200 1201 1202 1203 1204 1205
#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
1206
				split_huge_page_pmd(vma, addr, pmd);
S
Shaohua Li 已提交
1207
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1208
				goto next;
1209 1210
			/* fall through */
		}
1211 1212 1213 1214 1215 1216 1217 1218 1219
		/*
		 * 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;
1220
		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1221
next:
1222 1223
		cond_resched();
	} while (pmd++, addr = next, addr != end);
1224 1225

	return addr;
L
Linus Torvalds 已提交
1226 1227
}

1228
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1229
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1230
				unsigned long addr, unsigned long end,
1231
				struct zap_details *details)
L
Linus Torvalds 已提交
1232 1233 1234 1235 1236 1237 1238
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1239
		if (pud_none_or_clear_bad(pud))
L
Linus Torvalds 已提交
1240
			continue;
1241 1242
		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
	} while (pud++, addr = next, addr != end);
1243 1244

	return addr;
L
Linus Torvalds 已提交
1245 1246
}

A
Al Viro 已提交
1247 1248 1249 1250
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
1251 1252 1253 1254
{
	pgd_t *pgd;
	unsigned long next;

1255
	if (details && !details->check_mapping)
L
Linus Torvalds 已提交
1256 1257 1258 1259 1260 1261 1262
		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);
1263
		if (pgd_none_or_clear_bad(pgd))
L
Linus Torvalds 已提交
1264
			continue;
1265 1266
		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
	} while (pgd++, addr = next, addr != end);
L
Linus Torvalds 已提交
1267 1268
	tlb_end_vma(tlb, vma);
}
1269

1270 1271 1272

static void unmap_single_vma(struct mmu_gather *tlb,
		struct vm_area_struct *vma, unsigned long start_addr,
1273
		unsigned long end_addr,
1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284
		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;

1285 1286 1287
	if (vma->vm_file)
		uprobe_munmap(vma, start, end);

1288
	if (unlikely(vma->vm_flags & VM_PFNMAP))
1289
		untrack_pfn(vma, 0, 0);
1290 1291 1292 1293 1294 1295 1296

	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
1297
			 * cleanup path of mmap_region. When
1298
			 * hugetlbfs ->mmap method fails,
1299
			 * mmap_region() nullifies vma->vm_file
1300 1301 1302 1303
			 * before calling this function to clean up.
			 * Since no pte has actually been setup, it is
			 * safe to do nothing in this case.
			 */
1304
			if (vma->vm_file) {
1305
				i_mmap_lock_write(vma->vm_file->f_mapping);
1306
				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1307
				i_mmap_unlock_write(vma->vm_file->f_mapping);
1308
			}
1309 1310 1311
		} else
			unmap_page_range(tlb, vma, start, end, details);
	}
L
Linus Torvalds 已提交
1312 1313 1314 1315
}

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
1316
 * @tlb: address of the caller's struct mmu_gather
L
Linus Torvalds 已提交
1317 1318 1319 1320
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 *
1321
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1322 1323 1324 1325 1326 1327 1328 1329 1330 1331
 *
 * 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
1332
void unmap_vmas(struct mmu_gather *tlb,
L
Linus Torvalds 已提交
1333
		struct vm_area_struct *vma, unsigned long start_addr,
1334
		unsigned long end_addr)
L
Linus Torvalds 已提交
1335
{
A
Andrea Arcangeli 已提交
1336
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1337

A
Andrea Arcangeli 已提交
1338
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1339
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1340
		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
A
Andrea Arcangeli 已提交
1341
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1342 1343 1344 1345 1346
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
1347
 * @start: starting address of pages to zap
L
Linus Torvalds 已提交
1348
 * @size: number of bytes to zap
1349
 * @details: details of shared cache invalidation
1350 1351
 *
 * Caller must protect the VMA list
L
Linus Torvalds 已提交
1352
 */
1353
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
L
Linus Torvalds 已提交
1354 1355 1356
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1357
	struct mmu_gather tlb;
1358
	unsigned long end = start + size;
L
Linus Torvalds 已提交
1359 1360

	lru_add_drain();
1361
	tlb_gather_mmu(&tlb, mm, start, end);
1362
	update_hiwater_rss(mm);
1363 1364
	mmu_notifier_invalidate_range_start(mm, start, end);
	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1365
		unmap_single_vma(&tlb, vma, start, end, details);
1366 1367
	mmu_notifier_invalidate_range_end(mm, start, end);
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
1368 1369
}

1370 1371 1372 1373 1374
/**
 * 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
1375
 * @details: details of shared cache invalidation
1376 1377
 *
 * The range must fit into one VMA.
L
Linus Torvalds 已提交
1378
 */
1379
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1380 1381 1382
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1383
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1384 1385 1386
	unsigned long end = address + size;

	lru_add_drain();
1387
	tlb_gather_mmu(&tlb, mm, address, end);
1388
	update_hiwater_rss(mm);
1389
	mmu_notifier_invalidate_range_start(mm, address, end);
1390
	unmap_single_vma(&tlb, vma, address, end, details);
1391
	mmu_notifier_invalidate_range_end(mm, address, end);
P
Peter Zijlstra 已提交
1392
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1393 1394
}

1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412
/**
 * 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;
1413
	zap_page_range_single(vma, address, size, NULL);
1414 1415 1416 1417
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

1418
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
1419
			spinlock_t **ptl)
1420 1421 1422 1423
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1424
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1425 1426
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
1427
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1428
		}
1429 1430 1431 1432
	}
	return NULL;
}

1433 1434 1435 1436 1437 1438 1439
/*
 * 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
1440 1441
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1442
{
N
Nick Piggin 已提交
1443
	struct mm_struct *mm = vma->vm_mm;
1444
	int retval;
1445
	pte_t *pte;
1446 1447
	spinlock_t *ptl;

1448
	retval = -EINVAL;
1449
	if (PageAnon(page))
1450
		goto out;
1451 1452
	retval = -ENOMEM;
	flush_dcache_page(page);
1453
	pte = get_locked_pte(mm, addr, &ptl);
1454
	if (!pte)
1455
		goto out;
1456 1457 1458 1459 1460 1461
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
1462
	inc_mm_counter_fast(mm, MM_FILEPAGES);
1463 1464 1465 1466
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1467 1468
	pte_unmap_unlock(pte, ptl);
	return retval;
1469 1470 1471 1472 1473 1474
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1475 1476 1477 1478 1479 1480
/**
 * 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
 *
1481 1482 1483 1484 1485 1486
 * 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
1487
 * (see split_page()).
1488 1489 1490 1491 1492 1493 1494 1495
 *
 * 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.
1496 1497 1498 1499 1500
 *
 * 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.
1501
 */
N
Nick Piggin 已提交
1502 1503
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1504 1505 1506 1507 1508
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1509 1510 1511 1512 1513
	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
1514
	return insert_page(vma, addr, page, vma->vm_page_prot);
1515
}
1516
EXPORT_SYMBOL(vm_insert_page);
1517

N
Nick Piggin 已提交
1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536
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);
1537
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1538 1539 1540 1541 1542 1543 1544 1545

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

N
Nick Piggin 已提交
1546 1547 1548 1549 1550 1551
/**
 * 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
 *
1552
 * Similar to vm_insert_page, this allows drivers to insert individual pages
N
Nick Piggin 已提交
1553 1554 1555 1556
 * 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
1557 1558 1559 1560 1561
 *
 * 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
1562 1563
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1564
			unsigned long pfn)
N
Nick Piggin 已提交
1565
{
1566
	int ret;
1567
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1568 1569 1570 1571 1572 1573
	/*
	 * 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
1574 1575 1576 1577 1578
	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
1579

N
Nick Piggin 已提交
1580 1581
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1582
	if (track_pfn_insert(vma, &pgprot, pfn))
1583 1584
		return -EINVAL;

1585
	ret = insert_pfn(vma, addr, pfn, pgprot);
1586 1587

	return ret;
N
Nick Piggin 已提交
1588 1589
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1590

N
Nick Piggin 已提交
1591 1592 1593 1594
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
1595

N
Nick Piggin 已提交
1596 1597
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1598

N
Nick Piggin 已提交
1599 1600 1601 1602
	/*
	 * 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
1603 1604
	 * 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
1605 1606 1607 1608 1609 1610 1611 1612
	 */
	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
1613
}
N
Nick Piggin 已提交
1614
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1615

L
Linus Torvalds 已提交
1616 1617 1618 1619 1620 1621 1622 1623 1624 1625
/*
 * 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
1626
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1627

H
Hugh Dickins 已提交
1628
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1629 1630
	if (!pte)
		return -ENOMEM;
1631
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1632 1633
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1634
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1635 1636
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1637
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1638
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652
	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;
1653
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682
	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;
}

1683 1684 1685 1686 1687 1688 1689 1690 1691 1692
/**
 * 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
1693 1694 1695 1696 1697
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;
1698
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1699 1700 1701 1702 1703 1704 1705 1706
	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).
1707 1708 1709
	 *   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.
1710 1711 1712 1713
	 *   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
1714 1715 1716 1717
	 *
	 * 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".
1718
	 * See vm_normal_page() for details.
L
Linus Torvalds 已提交
1719
	 */
1720 1721 1722
	if (is_cow_mapping(vma->vm_flags)) {
		if (addr != vma->vm_start || end != vma->vm_end)
			return -EINVAL;
L
Linus Torvalds 已提交
1723
		vma->vm_pgoff = pfn;
1724 1725 1726 1727
	}

	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
	if (err)
1728
		return -EINVAL;
L
Linus Torvalds 已提交
1729

1730
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
L
Linus Torvalds 已提交
1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742

	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);
1743 1744

	if (err)
1745
		untrack_pfn(vma, pfn, PAGE_ALIGN(size));
1746

L
Linus Torvalds 已提交
1747 1748 1749 1750
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797
/**
 * 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);

1798 1799 1800 1801 1802 1803
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;
1804
	pgtable_t token;
1805
	spinlock_t *uninitialized_var(ptl);
1806 1807 1808 1809 1810 1811 1812 1813 1814

	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));

1815 1816
	arch_enter_lazy_mmu_mode();

1817
	token = pmd_pgtable(*pmd);
1818 1819

	do {
1820
		err = fn(pte++, token, addr, data);
1821 1822
		if (err)
			break;
1823
	} while (addr += PAGE_SIZE, addr != end);
1824

1825 1826
	arch_leave_lazy_mmu_mode();

1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839
	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
1840 1841
	BUG_ON(pud_huge(*pud));

1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882
	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;
1883
	unsigned long end = addr + size;
1884 1885 1886 1887 1888 1889 1890 1891 1892 1893
	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);
1894

1895 1896 1897 1898
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1899
/*
1900 1901 1902 1903 1904
 * handle_pte_fault chooses page fault handler according to an entry which was
 * read non-atomically.  Before making any commitment, on those architectures
 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
 * parts, do_swap_page must check under lock before unmapping the pte and
 * proceeding (but do_wp_page is only called after already making such a check;
1905
 * and do_anonymous_page can safely check later on).
1906
 */
H
Hugh Dickins 已提交
1907
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1908 1909 1910 1911 1912
				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
1913 1914
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1915
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1916
		spin_unlock(ptl);
1917 1918 1919 1920 1921 1922
	}
#endif
	pte_unmap(page_table);
	return same;
}

1923
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1924
{
1925 1926
	debug_dma_assert_idle(src);

1927 1928 1929 1930 1931 1932 1933
	/*
	 * 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)) {
1934
		void *kaddr = kmap_atomic(dst);
L
Linus Torvalds 已提交
1935 1936 1937 1938 1939 1940 1941 1942 1943
		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))
1944
			clear_page(kaddr);
1945
		kunmap_atomic(kaddr);
1946
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1947 1948
	} else
		copy_user_highpage(dst, src, va, vma);
1949 1950
}

1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966
/*
 * 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;
1967
	vmf.cow_page = NULL;
1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983

	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;
}

1984 1985 1986 1987 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 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042
/*
 * Handle write page faults for pages that can be reused in the current vma
 *
 * This can happen either due to the mapping being with the VM_SHARED flag,
 * or due to us being the last reference standing to the page. In either
 * case, all we need to do here is to mark the page as writable and update
 * any related book-keeping.
 */
static inline int wp_page_reuse(struct mm_struct *mm,
			struct vm_area_struct *vma, unsigned long address,
			pte_t *page_table, spinlock_t *ptl, pte_t orig_pte,
			struct page *page, int page_mkwrite,
			int dirty_shared)
	__releases(ptl)
{
	pte_t entry;
	/*
	 * Clear the pages cpupid information as the existing
	 * information potentially belongs to a now completely
	 * unrelated process.
	 */
	if (page)
		page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);

	flush_cache_page(vma, address, pte_pfn(orig_pte));
	entry = pte_mkyoung(orig_pte);
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
	if (ptep_set_access_flags(vma, address, page_table, entry, 1))
		update_mmu_cache(vma, address, page_table);
	pte_unmap_unlock(page_table, ptl);

	if (dirty_shared) {
		struct address_space *mapping;
		int dirtied;

		if (!page_mkwrite)
			lock_page(page);

		dirtied = set_page_dirty(page);
		VM_BUG_ON_PAGE(PageAnon(page), page);
		mapping = page->mapping;
		unlock_page(page);
		page_cache_release(page);

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

		if (!page_mkwrite)
			file_update_time(vma->vm_file);
	}

	return VM_FAULT_WRITE;
}

2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182
/*
 * Handle the case of a page which we actually need to copy to a new page.
 *
 * Called with mmap_sem locked and the old page referenced, but
 * without the ptl held.
 *
 * High level logic flow:
 *
 * - Allocate a page, copy the content of the old page to the new one.
 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
 * - Take the PTL. If the pte changed, bail out and release the allocated page
 * - If the pte is still the way we remember it, update the page table and all
 *   relevant references. This includes dropping the reference the page-table
 *   held to the old page, as well as updating the rmap.
 * - In any case, unlock the PTL and drop the reference we took to the old page.
 */
static int wp_page_copy(struct mm_struct *mm, struct vm_area_struct *vma,
			unsigned long address, pte_t *page_table, pmd_t *pmd,
			pte_t orig_pte, struct page *old_page)
{
	struct page *new_page = NULL;
	spinlock_t *ptl = NULL;
	pte_t entry;
	int page_copied = 0;
	const unsigned long mmun_start = address & PAGE_MASK;	/* For mmu_notifiers */
	const unsigned long mmun_end = mmun_start + PAGE_SIZE;	/* For mmu_notifiers */
	struct mem_cgroup *memcg;

	if (unlikely(anon_vma_prepare(vma)))
		goto oom;

	if (is_zero_pfn(pte_pfn(orig_pte))) {
		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);

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

	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);

	/*
	 * Re-check the pte - we dropped the lock
	 */
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (likely(pte_same(*page_table, orig_pte))) {
		if (old_page) {
			if (!PageAnon(old_page)) {
				dec_mm_counter_fast(mm, MM_FILEPAGES);
				inc_mm_counter_fast(mm, MM_ANONPAGES);
			}
		} else {
			inc_mm_counter_fast(mm, MM_ANONPAGES);
		}
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		/*
		 * 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.
		 */
		ptep_clear_flush_notify(vma, address, page_table);
		page_add_new_anon_rmap(new_page, vma, address);
		mem_cgroup_commit_charge(new_page, memcg, false);
		lru_cache_add_active_or_unevictable(new_page, vma);
		/*
		 * 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);
		update_mmu_cache(vma, address, page_table);
		if (old_page) {
			/*
			 * Only after switching the pte to the new page may
			 * we remove the mapcount here. Otherwise another
			 * process may come and find the rmap count decremented
			 * before the pte is switched to the new page, and
			 * "reuse" the old page writing into it while our pte
			 * here still points into it and can be read by other
			 * threads.
			 *
			 * The critical issue is to order this
			 * page_remove_rmap with the ptp_clear_flush above.
			 * Those stores are ordered by (if nothing else,)
			 * the barrier present in the atomic_add_negative
			 * in page_remove_rmap.
			 *
			 * Then the TLB flush in ptep_clear_flush ensures that
			 * no process can access the old page before the
			 * decremented mapcount is visible. And the old page
			 * cannot be reused until after the decremented
			 * mapcount is visible. So transitively, TLBs to
			 * old page will be flushed before it can be reused.
			 */
			page_remove_rmap(old_page);
		}

		/* Free the old page.. */
		new_page = old_page;
		page_copied = 1;
	} else {
		mem_cgroup_cancel_charge(new_page, memcg);
	}

	if (new_page)
		page_cache_release(new_page);

	pte_unmap_unlock(page_table, ptl);
	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
	if (old_page) {
		/*
		 * Don't let another task, with possibly unlocked vma,
		 * keep the mlocked page.
		 */
		if (page_copied && (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);
	}
	return page_copied ? VM_FAULT_WRITE : 0;
oom_free_new:
	page_cache_release(new_page);
oom:
	if (old_page)
		page_cache_release(old_page);
	return VM_FAULT_OOM;
}

2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228
static int wp_page_shared(struct mm_struct *mm, struct vm_area_struct *vma,
			  unsigned long address, pte_t *page_table,
			  pmd_t *pmd, spinlock_t *ptl, pte_t orig_pte,
			  struct page *old_page)
	__releases(ptl)
{
	int page_mkwrite = 0;

	page_cache_get(old_page);

	/*
	 * Only catch write-faults on shared writable pages,
	 * read-only shared pages can get COWed by
	 * get_user_pages(.write=1, .force=1).
	 */
	if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
		int tmp;

		pte_unmap_unlock(page_table, ptl);
		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;
		}
		/*
		 * 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);
		if (!pte_same(*page_table, orig_pte)) {
			unlock_page(old_page);
			pte_unmap_unlock(page_table, ptl);
			page_cache_release(old_page);
			return 0;
		}
		page_mkwrite = 1;
	}

	return wp_page_reuse(mm, vma, address, page_table, ptl,
			     orig_pte, old_page, page_mkwrite, 1);
}

L
Linus Torvalds 已提交
2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242
/*
 * 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.
 *
2243 2244 2245
 * 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
2246
 */
2247 2248
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2249
		spinlock_t *ptl, pte_t orig_pte)
2250
	__releases(ptl)
L
Linus Torvalds 已提交
2251
{
2252
	struct page *old_page;
L
Linus Torvalds 已提交
2253

2254
	old_page = vm_normal_page(vma, address, orig_pte);
2255 2256
	if (!old_page) {
		/*
2257 2258
		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
		 * VM_PFNMAP VMA.
2259 2260 2261 2262 2263 2264 2265
		 *
		 * 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))
2266 2267
			return wp_page_reuse(mm, vma, address, page_table, ptl,
					     orig_pte, old_page, 0, 0);
2268 2269 2270 2271

		pte_unmap_unlock(page_table, ptl);
		return wp_page_copy(mm, vma, address, page_table, pmd,
				    orig_pte, old_page);
2272
	}
L
Linus Torvalds 已提交
2273

2274
	/*
P
Peter Zijlstra 已提交
2275 2276
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2277
	 */
H
Hugh Dickins 已提交
2278
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2279 2280 2281 2282 2283 2284 2285 2286
		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);
2287 2288 2289
				pte_unmap_unlock(page_table, ptl);
				page_cache_release(old_page);
				return 0;
2290 2291
			}
			page_cache_release(old_page);
P
Peter Zijlstra 已提交
2292
		}
2293
		if (reuse_swap_page(old_page)) {
2294 2295 2296 2297 2298 2299
			/*
			 * 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);
2300
			unlock_page(old_page);
2301 2302
			return wp_page_reuse(mm, vma, address, page_table, ptl,
					     orig_pte, old_page, 0, 0);
2303
		}
2304
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2305
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2306
					(VM_WRITE|VM_SHARED))) {
2307 2308
		return wp_page_shared(mm, vma, address, page_table, pmd,
				      ptl, orig_pte, old_page);
L
Linus Torvalds 已提交
2309 2310 2311 2312 2313
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2314
	page_cache_get(old_page);
2315

2316
	pte_unmap_unlock(page_table, ptl);
2317 2318
	return wp_page_copy(mm, vma, address, page_table, pmd,
			    orig_pte, old_page);
L
Linus Torvalds 已提交
2319 2320
}

2321
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2322 2323 2324
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
2325
	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
L
Linus Torvalds 已提交
2326 2327
}

2328
static inline void unmap_mapping_range_tree(struct rb_root *root,
L
Linus Torvalds 已提交
2329 2330 2331 2332 2333
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	pgoff_t vba, vea, zba, zea;

2334
	vma_interval_tree_foreach(vma, root,
L
Linus Torvalds 已提交
2335 2336 2337
			details->first_index, details->last_index) {

		vba = vma->vm_pgoff;
2338
		vea = vba + vma_pages(vma) - 1;
L
Linus Torvalds 已提交
2339 2340 2341 2342 2343 2344 2345 2346
		/* 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;

2347
		unmap_mapping_range_vma(vma,
L
Linus Torvalds 已提交
2348 2349
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2350
				details);
L
Linus Torvalds 已提交
2351 2352 2353 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
 * must keep the partial page.  In contrast, we must get rid of
 * partial pages.
 * @holelen: size of prospective hole in bytes.  This will be rounded
 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
 * end of the file.
 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
 * but 0 when invalidating pagecache, don't throw away private data.
 */
void unmap_mapping_range(struct address_space *mapping,
		loff_t const holebegin, loff_t const holelen, int even_cows)
{
	struct zap_details details;
	pgoff_t hba = holebegin >> PAGE_SHIFT;
	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;

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

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


2393
	/* DAX uses i_mmap_lock to serialise file truncate vs page fault */
2394
	i_mmap_lock_write(mapping);
2395
	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
L
Linus Torvalds 已提交
2396
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
2397
	i_mmap_unlock_write(mapping);
L
Linus Torvalds 已提交
2398 2399 2400 2401
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
2402 2403
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
2404 2405 2406 2407
 * 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
2408
 */
2409 2410
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2411
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2412
{
2413
	spinlock_t *ptl;
2414
	struct page *page, *swapcache;
2415
	struct mem_cgroup *memcg;
2416
	swp_entry_t entry;
L
Linus Torvalds 已提交
2417
	pte_t pte;
2418
	int locked;
2419
	int exclusive = 0;
N
Nick Piggin 已提交
2420
	int ret = 0;
L
Linus Torvalds 已提交
2421

H
Hugh Dickins 已提交
2422
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2423
		goto out;
2424 2425

	entry = pte_to_swp_entry(orig_pte);
2426 2427 2428 2429 2430 2431 2432
	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
2433
			ret = VM_FAULT_SIGBUS;
2434
		}
2435 2436
		goto out;
	}
2437
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2438 2439
	page = lookup_swap_cache(entry);
	if (!page) {
2440 2441
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2442 2443
		if (!page) {
			/*
2444 2445
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2446
			 */
2447
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2448 2449
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2450
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2451
			goto unlock;
L
Linus Torvalds 已提交
2452 2453 2454 2455
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2456
		count_vm_event(PGMAJFAULT);
2457
		mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2458
	} else if (PageHWPoison(page)) {
2459 2460 2461 2462
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2463 2464
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2465
		swapcache = page;
2466
		goto out_release;
L
Linus Torvalds 已提交
2467 2468
	}

2469
	swapcache = page;
2470
	locked = lock_page_or_retry(page, mm, flags);
R
Rik van Riel 已提交
2471

2472
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2473 2474 2475 2476
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2477

A
Andrea Arcangeli 已提交
2478
	/*
2479 2480 2481 2482
	 * 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
2483
	 */
2484
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2485 2486
		goto out_page;

2487 2488 2489 2490 2491
	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
2492 2493
	}

2494
	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg)) {
2495
		ret = VM_FAULT_OOM;
2496
		goto out_page;
2497 2498
	}

L
Linus Torvalds 已提交
2499
	/*
2500
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2501
	 */
2502
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2503
	if (unlikely(!pte_same(*page_table, orig_pte)))
2504 2505 2506 2507 2508
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2509 2510
	}

2511 2512 2513 2514 2515 2516 2517 2518 2519
	/*
	 * 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
2520

2521
	inc_mm_counter_fast(mm, MM_ANONPAGES);
K
KAMEZAWA Hiroyuki 已提交
2522
	dec_mm_counter_fast(mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
2523
	pte = mk_pte(page, vma->vm_page_prot);
2524
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2525
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2526
		flags &= ~FAULT_FLAG_WRITE;
2527
		ret |= VM_FAULT_WRITE;
2528
		exclusive = 1;
L
Linus Torvalds 已提交
2529 2530
	}
	flush_icache_page(vma, page);
2531 2532
	if (pte_swp_soft_dirty(orig_pte))
		pte = pte_mksoft_dirty(pte);
L
Linus Torvalds 已提交
2533
	set_pte_at(mm, address, page_table, pte);
2534
	if (page == swapcache) {
2535
		do_page_add_anon_rmap(page, vma, address, exclusive);
2536 2537
		mem_cgroup_commit_charge(page, memcg, true);
	} else { /* ksm created a completely new copy */
2538
		page_add_new_anon_rmap(page, vma, address);
2539 2540 2541
		mem_cgroup_commit_charge(page, memcg, false);
		lru_cache_add_active_or_unevictable(page, vma);
	}
L
Linus Torvalds 已提交
2542

2543
	swap_free(entry);
N
Nick Piggin 已提交
2544
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2545
		try_to_free_swap(page);
2546
	unlock_page(page);
2547
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558
		/*
		 * 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);
	}
2559

2560
	if (flags & FAULT_FLAG_WRITE) {
2561 2562 2563
		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
2564 2565 2566 2567
		goto out;
	}

	/* No need to invalidate - it was non-present before */
2568
	update_mmu_cache(vma, address, page_table);
2569
unlock:
2570
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2571 2572
out:
	return ret;
2573
out_nomap:
2574
	mem_cgroup_cancel_charge(page, memcg);
2575
	pte_unmap_unlock(page_table, ptl);
2576
out_page:
2577
	unlock_page(page);
2578
out_release:
2579
	page_cache_release(page);
2580
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2581 2582 2583
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
2584
	return ret;
L
Linus Torvalds 已提交
2585 2586
}

2587
/*
2588 2589
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2590 2591 2592 2593 2594 2595
 * 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) {
2596 2597 2598 2599 2600 2601 2602 2603 2604 2605
		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;
2606

2607
		return expand_downwards(vma, address - PAGE_SIZE);
2608
	}
2609 2610 2611 2612 2613 2614 2615
	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;

2616
		return expand_upwards(vma, address + PAGE_SIZE);
2617
	}
2618 2619 2620
	return 0;
}

L
Linus Torvalds 已提交
2621
/*
2622 2623 2624
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2625
 */
2626 2627
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2628
		unsigned int flags)
L
Linus Torvalds 已提交
2629
{
2630
	struct mem_cgroup *memcg;
2631 2632
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2633 2634
	pte_t entry;

2635 2636 2637 2638
	pte_unmap(page_table);

	/* Check if we need to add a guard page to the stack */
	if (check_stack_guard_page(vma, address) < 0)
2639
		return VM_FAULT_SIGSEGV;
2640

2641
	/* Use the zero-page for reads */
2642
	if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
H
Hugh Dickins 已提交
2643 2644
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
2645
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2646 2647 2648 2649 2650
		if (!pte_none(*page_table))
			goto unlock;
		goto setpte;
	}

N
Nick Piggin 已提交
2651 2652 2653 2654 2655 2656
	/* 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;
2657 2658 2659 2660 2661
	/*
	 * 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
2662
	__SetPageUptodate(page);
2663

2664
	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg))
2665 2666
		goto oom_free_page;

N
Nick Piggin 已提交
2667
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
2668 2669
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
2670

N
Nick Piggin 已提交
2671
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2672
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
2673
		goto release;
H
Hugh Dickins 已提交
2674

2675
	inc_mm_counter_fast(mm, MM_ANONPAGES);
N
Nick Piggin 已提交
2676
	page_add_new_anon_rmap(page, vma, address);
2677 2678
	mem_cgroup_commit_charge(page, memcg, false);
	lru_cache_add_active_or_unevictable(page, vma);
H
Hugh Dickins 已提交
2679
setpte:
2680
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2681 2682

	/* No need to invalidate - it was non-present before */
2683
	update_mmu_cache(vma, address, page_table);
2684
unlock:
2685
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2686
	return 0;
2687
release:
2688
	mem_cgroup_cancel_charge(page, memcg);
2689 2690
	page_cache_release(page);
	goto unlock;
2691
oom_free_page:
2692
	page_cache_release(page);
2693
oom:
L
Linus Torvalds 已提交
2694 2695 2696
	return VM_FAULT_OOM;
}

2697 2698 2699 2700 2701
/*
 * 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().
 */
2702
static int __do_fault(struct vm_area_struct *vma, unsigned long address,
2703 2704
			pgoff_t pgoff, unsigned int flags,
			struct page *cow_page, struct page **page)
2705 2706 2707 2708 2709 2710 2711 2712
{
	struct vm_fault vmf;
	int ret;

	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
2713
	vmf.cow_page = cow_page;
2714 2715 2716 2717

	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		return ret;
2718 2719
	if (!vmf.page)
		goto out;
2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732

	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);

2733
 out:
2734 2735 2736 2737
	*page = vmf.page;
	return ret;
}

2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753
/**
 * 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,
2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774
		struct page *page, pte_t *pte, bool write, bool anon)
{
	pte_t entry;

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

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

2775 2776
static unsigned long fault_around_bytes __read_mostly =
	rounddown_pow_of_two(65536);
2777 2778 2779

#ifdef CONFIG_DEBUG_FS
static int fault_around_bytes_get(void *data, u64 *val)
2780
{
2781
	*val = fault_around_bytes;
2782 2783 2784
	return 0;
}

2785 2786 2787 2788 2789
/*
 * 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.
 */
2790
static int fault_around_bytes_set(void *data, u64 val)
2791
{
2792
	if (val / PAGE_SIZE > PTRS_PER_PTE)
2793
		return -EINVAL;
2794 2795 2796 2797
	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 */
2798 2799
	return 0;
}
2800 2801
DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
		fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
2802 2803 2804 2805 2806

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

2807 2808
	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
			&fault_around_bytes_fops);
2809
	if (!ret)
2810
		pr_warn("Failed to create fault_around_bytes in debugfs");
2811 2812 2813 2814
	return 0;
}
late_initcall(fault_around_debugfs);
#endif
2815

2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838
/*
 * 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.
 */
2839 2840 2841
static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pgoff_t pgoff, unsigned int flags)
{
2842
	unsigned long start_addr, nr_pages, mask;
2843 2844 2845 2846
	pgoff_t max_pgoff;
	struct vm_fault vmf;
	int off;

2847
	nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
2848 2849 2850
	mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;

	start_addr = max(address & mask, vma->vm_start);
2851 2852 2853 2854 2855 2856
	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
2857
	 *  or fault_around_pages() from pgoff, depending what is nearest.
2858 2859 2860 2861
	 */
	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,
2862
			pgoff + nr_pages - 1);
2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881

	/* 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);
}

2882 2883 2884 2885 2886 2887
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;
2888
	pte_t *pte;
2889 2890 2891 2892 2893 2894 2895
	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).
	 */
2896
	if (vma->vm_ops->map_pages && 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
	ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
2905 2906 2907 2908 2909 2910 2911 2912 2913 2914
	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
		page_cache_release(new_page);
		return VM_FAULT_OOM;
	}

2944
	ret = __do_fault(vma, address, pgoff, flags, new_page, &fault_page);
2945 2946 2947
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		goto uncharge_out;

2948 2949
	if (fault_page)
		copy_user_highpage(new_page, fault_page, address, vma);
2950 2951 2952 2953 2954
	__SetPageUptodate(new_page);

	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (unlikely(!pte_same(*pte, orig_pte))) {
		pte_unmap_unlock(pte, ptl);
2955 2956 2957 2958 2959 2960 2961 2962 2963 2964
		if (fault_page) {
			unlock_page(fault_page);
			page_cache_release(fault_page);
		} else {
			/*
			 * The fault handler has no page to lock, so it holds
			 * i_mmap_lock for read to protect against truncate.
			 */
			i_mmap_unlock_read(vma->vm_file->f_mapping);
		}
2965 2966
		goto uncharge_out;
	}
2967
	do_set_pte(vma, address, new_page, pte, true, true);
2968 2969
	mem_cgroup_commit_charge(new_page, memcg, false);
	lru_cache_add_active_or_unevictable(new_page, vma);
2970
	pte_unmap_unlock(pte, ptl);
2971 2972 2973 2974 2975 2976 2977 2978 2979 2980
	if (fault_page) {
		unlock_page(fault_page);
		page_cache_release(fault_page);
	} else {
		/*
		 * The fault handler has no page to lock, so it holds
		 * i_mmap_lock for read to protect against truncate.
		 */
		i_mmap_unlock_read(vma->vm_file->f_mapping);
	}
2981 2982
	return ret;
uncharge_out:
2983
	mem_cgroup_cancel_charge(new_page, memcg);
2984 2985 2986 2987
	page_cache_release(new_page);
	return ret;
}

2988
static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2989
		unsigned long address, pmd_t *pmd,
2990
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2991
{
2992 2993
	struct page *fault_page;
	struct address_space *mapping;
2994
	spinlock_t *ptl;
2995
	pte_t *pte;
2996 2997
	int dirtied = 0;
	int ret, tmp;
2998

2999
	ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
3000
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3001
		return ret;
L
Linus Torvalds 已提交
3002 3003

	/*
3004 3005
	 * Check if the backing address space wants to know that the page is
	 * about to become writable
L
Linus Torvalds 已提交
3006
	 */
3007 3008 3009 3010 3011
	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)))) {
3012
			page_cache_release(fault_page);
3013
			return tmp;
3014
		}
3015 3016
	}

3017 3018 3019 3020 3021 3022
	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
3023
	}
3024
	do_set_pte(vma, address, fault_page, pte, true, false);
3025
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3026

3027 3028
	if (set_page_dirty(fault_page))
		dirtied = 1;
3029 3030 3031 3032 3033 3034
	/*
	 * Take a local copy of the address_space - page.mapping may be zeroed
	 * by truncate after unlock_page().   The address_space itself remains
	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
	 * release semantics to prevent the compiler from undoing this copying.
	 */
3035 3036 3037 3038 3039 3040 3041 3042
	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);
3043
	}
3044

3045
	if (!vma->vm_ops->page_mkwrite)
3046
		file_update_time(vma->vm_file);
N
Nick Piggin 已提交
3047

3048
	return ret;
3049
}
3050

3051 3052 3053 3054 3055 3056
/*
 * 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().
 */
3057
static int do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3058
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3059
		unsigned int flags, pte_t orig_pte)
3060 3061
{
	pgoff_t pgoff = (((address & PAGE_MASK)
3062
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3063

3064
	pte_unmap(page_table);
3065 3066 3067
	if (!(flags & FAULT_FLAG_WRITE))
		return do_read_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3068 3069 3070
	if (!(vma->vm_flags & VM_SHARED))
		return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3071
	return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3072 3073
}

3074
static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3075 3076
				unsigned long addr, int page_nid,
				int *flags)
3077 3078 3079 3080
{
	get_page(page);

	count_vm_numa_event(NUMA_HINT_FAULTS);
3081
	if (page_nid == numa_node_id()) {
3082
		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3083 3084
		*flags |= TNF_FAULT_LOCAL;
	}
3085 3086 3087 3088

	return mpol_misplaced(page, vma, addr);
}

3089
static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3090 3091
		   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
{
3092
	struct page *page = NULL;
3093
	spinlock_t *ptl;
3094
	int page_nid = -1;
3095
	int last_cpupid;
3096
	int target_nid;
3097
	bool migrated = false;
3098
	bool was_writable = pte_write(pte);
3099
	int flags = 0;
3100

3101 3102 3103
	/* A PROT_NONE fault should not end up here */
	BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));

3104 3105 3106 3107 3108
	/*
	* 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.
	*
3109 3110 3111
	* We can safely just do a "set_pte_at()", because the old
	* page table entry is not accessible, so there would be no
	* concurrent hardware modifications to the PTE.
3112 3113 3114
	*/
	ptl = pte_lockptr(mm, pmd);
	spin_lock(ptl);
3115 3116 3117 3118 3119
	if (unlikely(!pte_same(*ptep, pte))) {
		pte_unmap_unlock(ptep, ptl);
		goto out;
	}

3120 3121 3122
	/* Make it present again */
	pte = pte_modify(pte, vma->vm_page_prot);
	pte = pte_mkyoung(pte);
3123 3124
	if (was_writable)
		pte = pte_mkwrite(pte);
3125 3126 3127 3128 3129 3130 3131 3132 3133
	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;
	}

3134
	/*
3135 3136 3137 3138 3139 3140
	 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
	 * much anyway since they can be in shared cache state. This misses
	 * the case where a mapping is writable but the process never writes
	 * to it but pte_write gets cleared during protection updates and
	 * pte_dirty has unpredictable behaviour between PTE scan updates,
	 * background writeback, dirty balancing and application behaviour.
3141
	 */
3142
	if (!(vma->vm_flags & VM_WRITE))
3143 3144
		flags |= TNF_NO_GROUP;

3145 3146 3147 3148 3149 3150 3151
	/*
	 * 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;

3152
	last_cpupid = page_cpupid_last(page);
3153
	page_nid = page_to_nid(page);
3154
	target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3155
	pte_unmap_unlock(ptep, ptl);
3156 3157 3158 3159 3160 3161
	if (target_nid == -1) {
		put_page(page);
		goto out;
	}

	/* Migrate to the requested node */
3162
	migrated = migrate_misplaced_page(page, vma, target_nid);
3163
	if (migrated) {
3164
		page_nid = target_nid;
3165
		flags |= TNF_MIGRATED;
3166 3167
	} else
		flags |= TNF_MIGRATE_FAIL;
3168 3169

out:
3170
	if (page_nid != -1)
3171
		task_numa_fault(last_cpupid, page_nid, 1, flags);
3172 3173 3174
	return 0;
}

L
Linus Torvalds 已提交
3175 3176 3177 3178 3179 3180 3181 3182 3183
/*
 * 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
3184 3185
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
3186 3187 3188 3189
 * 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
3190
 */
3191
static int handle_pte_fault(struct mm_struct *mm,
3192 3193
		     struct vm_area_struct *vma, unsigned long address,
		     pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
3194 3195
{
	pte_t entry;
3196
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3197

3198 3199 3200 3201 3202 3203 3204 3205 3206 3207
	/*
	 * some architectures can have larger ptes than wordsize,
	 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and CONFIG_32BIT=y,
	 * so READ_ONCE or ACCESS_ONCE cannot guarantee atomic accesses.
	 * The code below just needs a consistent view for the ifs and
	 * we later double check anyway with the ptl lock held. So here
	 * a barrier will do.
	 */
	entry = *pte;
	barrier();
L
Linus Torvalds 已提交
3208
	if (!pte_present(entry)) {
3209
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
3210
			if (vma->vm_ops) {
N
Nick Piggin 已提交
3211
				if (likely(vma->vm_ops->fault))
3212 3213
					return do_fault(mm, vma, address, pte,
							pmd, flags, entry);
J
Jes Sorensen 已提交
3214 3215
			}
			return do_anonymous_page(mm, vma, address,
3216
						 pte, pmd, flags);
3217 3218
		}
		return do_swap_page(mm, vma, address,
3219
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
3220 3221
	}

3222
	if (pte_protnone(entry))
3223 3224
		return do_numa_page(mm, vma, address, entry, pte, pmd);

H
Hugh Dickins 已提交
3225
	ptl = pte_lockptr(mm, pmd);
3226 3227 3228
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
3229
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3230
		if (!pte_write(entry))
3231 3232
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
3233 3234 3235
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
3236
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3237
		update_mmu_cache(vma, address, pte);
3238 3239 3240 3241 3242 3243 3244
	} 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.
		 */
3245
		if (flags & FAULT_FLAG_WRITE)
3246
			flush_tlb_fix_spurious_fault(vma, address);
3247
	}
3248 3249
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3250
	return 0;
L
Linus Torvalds 已提交
3251 3252 3253 3254
}

/*
 * By the time we get here, we already hold the mm semaphore
3255 3256 3257
 *
 * 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
3258
 */
3259 3260
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
3261 3262 3263 3264 3265 3266
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

3267
	if (unlikely(is_vm_hugetlb_page(vma)))
3268
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3269 3270 3271 3272

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3273
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3274 3275
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3276
		return VM_FAULT_OOM;
3277
	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3278
		int ret = VM_FAULT_FALLBACK;
3279
		if (!vma->vm_ops)
3280 3281 3282 3283
			ret = do_huge_pmd_anonymous_page(mm, vma, address,
					pmd, flags);
		if (!(ret & VM_FAULT_FALLBACK))
			return ret;
3284 3285
	} else {
		pmd_t orig_pmd = *pmd;
3286 3287
		int ret;

3288 3289
		barrier();
		if (pmd_trans_huge(orig_pmd)) {
3290 3291
			unsigned int dirty = flags & FAULT_FLAG_WRITE;

3292 3293 3294 3295 3296 3297 3298 3299
			/*
			 * 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;

3300
			if (pmd_protnone(orig_pmd))
3301
				return do_huge_pmd_numa_page(mm, vma, address,
3302 3303
							     orig_pmd, pmd);

3304
			if (dirty && !pmd_write(orig_pmd)) {
3305 3306
				ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
							  orig_pmd);
3307 3308
				if (!(ret & VM_FAULT_FALLBACK))
					return ret;
3309 3310 3311
			} else {
				huge_pmd_set_accessed(mm, vma, address, pmd,
						      orig_pmd, dirty);
3312
				return 0;
3313
			}
3314 3315 3316 3317 3318 3319 3320 3321
		}
	}

	/*
	 * 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.
	 */
3322 3323
	if (unlikely(pmd_none(*pmd)) &&
	    unlikely(__pte_alloc(mm, vma, pmd, address)))
H
Hugh Dickins 已提交
3324
		return VM_FAULT_OOM;
3325 3326 3327 3328 3329 3330 3331 3332 3333 3334
	/* 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
3335

3336
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3337 3338
}

3339 3340 3341 3342 3343 3344
/*
 * 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().
 */
3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362
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)
3363
		mem_cgroup_oom_enable();
3364 3365 3366

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

3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377
	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);
	}
3378

3379 3380
	return ret;
}
3381
EXPORT_SYMBOL_GPL(handle_mm_fault);
3382

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 3422
	if (!pud_present(*pud)) {
		mm_inc_nr_pmds(mm);
3423
		pud_populate(mm, pud, new);
3424
	} else	/* Another has populated it */
3425
		pmd_free(mm, new);
3426 3427 3428
#else
	if (!pgd_present(*pud)) {
		mm_inc_nr_pmds(mm);
3429
		pgd_populate(mm, pud, new);
3430 3431
	} else /* Another has populated it */
		pmd_free(mm, new);
L
Linus Torvalds 已提交
3432
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3433
	spin_unlock(&mm->page_table_lock);
3434
	return 0;
3435
}
L
Linus Torvalds 已提交
3436 3437
#endif /* __PAGETABLE_PMD_FOLDED */

3438
static int __follow_pte(struct mm_struct *mm, unsigned long address,
J
Johannes Weiner 已提交
3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452 3453 3454
		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);
3455
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473 3474 3475
	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;
}

3476 3477 3478 3479 3480 3481 3482 3483 3484 3485 3486
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
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 3514 3515
/**
 * 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);

3516
#ifdef CONFIG_HAVE_IOREMAP_PROT
3517 3518 3519
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3520
{
3521
	int ret = -EINVAL;
3522 3523 3524
	pte_t *ptep, pte;
	spinlock_t *ptl;

3525 3526
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3527

3528
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3529
		goto out;
3530
	pte = *ptep;
3531

3532 3533 3534 3535
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3536
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3537

3538
	ret = 0;
3539 3540 3541
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3542
	return ret;
3543 3544 3545 3546 3547 3548 3549
}

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
3550
	void __iomem *maddr;
3551 3552
	int offset = addr & (PAGE_SIZE-1);

3553
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3554 3555
		return -EINVAL;

3556
	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
3557 3558 3559 3560 3561 3562 3563 3564
	if (write)
		memcpy_toio(maddr + offset, buf, len);
	else
		memcpy_fromio(buf, maddr + offset, len);
	iounmap(maddr);

	return len;
}
3565
EXPORT_SYMBOL_GPL(generic_access_phys);
3566 3567
#endif

3568
/*
3569 3570
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
3571
 */
3572 3573
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long addr, void *buf, int len, int write)
3574 3575 3576 3577 3578
{
	struct vm_area_struct *vma;
	void *old_buf = buf;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3579
	/* ignore errors, just check how much was successfully transferred */
3580 3581 3582
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3583
		struct page *page = NULL;
3584 3585 3586

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3587
		if (ret <= 0) {
3588 3589 3590
#ifndef CONFIG_HAVE_IOREMAP_PROT
			break;
#else
3591 3592 3593 3594 3595
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
			vma = find_vma(mm, addr);
3596
			if (!vma || vma->vm_start > addr)
3597 3598 3599 3600 3601 3602 3603
				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;
3604
#endif
3605
		} else {
3606 3607 3608 3609 3610 3611 3612 3613 3614 3615 3616 3617 3618 3619 3620 3621
			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);
3622 3623 3624 3625 3626 3627 3628 3629 3630
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
3631

S
Stephen Wilson 已提交
3632
/**
3633
 * access_remote_vm - access another process' address space
S
Stephen Wilson 已提交
3634 3635 3636 3637 3638 3639 3640 3641 3642 3643 3644 3645 3646 3647
 * @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);
}

3648 3649 3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660 3661 3662 3663 3664 3665 3666 3667 3668
/*
 * 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;
}

3669 3670 3671 3672 3673 3674 3675 3676
/*
 * 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;

3677 3678 3679 3680 3681 3682 3683
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3684 3685 3686 3687 3688 3689
	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
3690
			char *p;
3691

3692
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3693 3694
			if (IS_ERR(p))
				p = "?";
A
Andy Shevchenko 已提交
3695
			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3696 3697 3698 3699 3700
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
3701
	up_read(&mm->mmap_sem);
3702
}
3703

3704
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3705 3706
void might_fault(void)
{
3707 3708 3709 3710 3711 3712 3713 3714 3715
	/*
	 * 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;

3716 3717 3718 3719 3720
	/*
	 * 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.
	 */
3721 3722 3723 3724 3725 3726
	if (in_atomic())
		return;

	__might_sleep(__FILE__, __LINE__, 0);

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

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

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

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

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

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

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

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

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

	might_sleep();
	for (i = 0; i < pages_per_huge_page; i++) {
		cond_resched();
		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
	}
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
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3803
#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
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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);
}

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

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	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
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	if (!ptl)
		return false;
3820
	page->ptl = ptl;
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	return true;
}

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