memory.c 107.3 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

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

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

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

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

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/export.h>
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#include <linux/delayacct.h>
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#include <linux/init.h>
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#include <linux/pfn_t.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 <linux/userfaultfd_k.h>
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#include <asm/io.h>
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#include <asm/mmu_context.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

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

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

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	if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
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		return false;
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	batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
	if (!batch)
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		return false;
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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;

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	return true;
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}

/* 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, 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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	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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	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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	}
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	spin_unlock(ptl);
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	if (new)
		pte_free(mm, new);
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	return 0;
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}

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int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
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{
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	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
	if (!new)
		return -ENOMEM;

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

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	spin_lock(&init_mm.page_table_lock);
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	if (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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	}
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	spin_unlock(&init_mm.page_table_lock);
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	if (new)
		pte_free_kernel(&init_mm, new);
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	return 0;
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}

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static inline void 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)
625
{
K
KAMEZAWA Hiroyuki 已提交
626 627
	int i;

628
	if (current->mm == mm)
629
		sync_mm_rss(mm);
K
KAMEZAWA Hiroyuki 已提交
630 631 632
	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
633 634
}

N
Nick Piggin 已提交
635
/*
636 637 638
 * 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
639 640 641
 *
 * The calling function must still handle the error.
 */
642 643
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
644
{
645 646 647 648 649
	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;
650 651 652 653 654 655 656 657 658 659 660 661 662 663
	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) {
664 665
			pr_alert("BUG: Bad page map: %lu messages suppressed\n",
				 nr_unshown);
666 667 668 669 670 671
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
672 673 674 675

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

676 677 678
	pr_alert("BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
		 current->comm,
		 (long long)pte_val(pte), (long long)pmd_val(*pmd));
679
	if (page)
680
		dump_page(page, "bad pte");
681 682
	pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
		 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
683 684 685
	/*
	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
	 */
686 687 688 689 690
	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
691
	dump_stack();
692
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
N
Nick Piggin 已提交
693 694
}

H
Hugh Dickins 已提交
695
/*
N
Nick Piggin 已提交
696
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
697
 *
N
Nick Piggin 已提交
698 699 700
 * "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
701
 *
N
Nick Piggin 已提交
702 703 704 705 706 707 708 709
 * 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.
710
 *
J
Jared Hulbert 已提交
711 712
 * 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
713 714
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
715 716 717
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
718 719 720 721 722 723
 * 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
724 725
 *
 *
N
Nick Piggin 已提交
726
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
727 728 729 730 731 732 733 734 735
 *
 * 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
736
 */
N
Nick Piggin 已提交
737 738 739 740 741 742 743
#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
744
{
745
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
746 747

	if (HAVE_PTE_SPECIAL) {
748
		if (likely(!pte_special(pte)))
749
			goto check_pfn;
750 751
		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
752 753
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
754
		if (!is_zero_pfn(pfn))
755
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
756 757 758 759 760
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
761 762 763 764 765 766
	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
767 768
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
769 770 771 772 773
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
774 775
	}

776 777
	if (is_zero_pfn(pfn))
		return NULL;
778 779 780 781 782
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
783 784

	/*
N
Nick Piggin 已提交
785 786
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
787
	 */
J
Jared Hulbert 已提交
788
out:
789
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
790 791
}

792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
				pmd_t pmd)
{
	unsigned long pfn = pmd_pfn(pmd);

	/*
	 * There is no pmd_special() but there may be special pmds, e.g.
	 * in a direct-access (dax) mapping, so let's just replicate the
	 * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
	 */
	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
	}

	if (is_zero_pfn(pfn))
		return NULL;
	if (unlikely(pfn > highest_memmap_pfn))
		return NULL;

	/*
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
	 */
out:
	return pfn_to_page(pfn);
}
#endif

L
Linus Torvalds 已提交
832 833 834 835 836 837
/*
 * 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
838
static inline unsigned long
L
Linus Torvalds 已提交
839
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
840
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
841
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
842
{
N
Nick Piggin 已提交
843
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
844 845 846 847 848
	pte_t pte = *src_pte;
	struct page *page;

	/* pte contains position in swap or file, so copy. */
	if (unlikely(!pte_present(pte))) {
849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866
		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);

867
			rss[mm_counter(page)]++;
868 869 870 871 872 873 874 875 876 877 878 879

			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);
880
			}
L
Linus Torvalds 已提交
881
		}
882
		goto out_set_pte;
L
Linus Torvalds 已提交
883 884 885 886 887 888
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
889
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
890
		ptep_set_wrprotect(src_mm, addr, src_pte);
891
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
892 893 894 895 896 897 898 899 900
	}

	/*
	 * 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);
901 902 903 904

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
905
		page_dup_rmap(page, false);
906
		rss[mm_counter(page)]++;
907
	}
908 909 910

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
911
	return 0;
L
Linus Torvalds 已提交
912 913
}

914
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
915 916
		   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
917
{
918
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
919
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
920
	spinlock_t *src_ptl, *dst_ptl;
921
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
922
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
923
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
924 925

again:
K
KAMEZAWA Hiroyuki 已提交
926 927
	init_rss_vec(rss);

H
Hugh Dickins 已提交
928
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
929 930
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
931
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
932
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
933
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
934 935
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
936
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
937 938 939 940 941 942

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
943 944 945
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
946
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
947 948
				break;
		}
L
Linus Torvalds 已提交
949 950 951 952
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
953 954 955 956
		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
957 958 959
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

960
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
961
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
962
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
963
	add_mm_rss_vec(dst_mm, rss);
964
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
965
	cond_resched();
H
Hugh Dickins 已提交
966 967 968 969 970 971

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989
	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);
990
		if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
991
			int err;
992
			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
993 994 995 996 997 998 999 1000
			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
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038
		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;
1039 1040 1041
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	bool is_cow;
A
Andrea Arcangeli 已提交
1042
	int ret;
L
Linus Torvalds 已提交
1043

1044 1045 1046 1047 1048 1049
	/*
	 * 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.
	 */
1050 1051 1052
	if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
			!vma->anon_vma)
		return 0;
1053

L
Linus Torvalds 已提交
1054 1055 1056
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

1057
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1058 1059 1060 1061
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
1062
		ret = track_pfn_copy(vma);
1063 1064 1065 1066
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
1067 1068 1069 1070 1071 1072
	/*
	 * 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.
	 */
1073 1074 1075 1076 1077 1078
	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
1079 1080

	ret = 0;
L
Linus Torvalds 已提交
1081 1082 1083 1084 1085 1086
	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
1087 1088 1089 1090 1091
		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
1092
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1093

1094 1095
	if (is_cow)
		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
A
Andrea Arcangeli 已提交
1096
	return ret;
L
Linus Torvalds 已提交
1097 1098
}

1099
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1100
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
1101
				unsigned long addr, unsigned long end,
1102
				struct zap_details *details)
L
Linus Torvalds 已提交
1103
{
N
Nick Piggin 已提交
1104
	struct mm_struct *mm = tlb->mm;
P
Peter Zijlstra 已提交
1105
	int force_flush = 0;
K
KAMEZAWA Hiroyuki 已提交
1106
	int rss[NR_MM_COUNTERS];
1107
	spinlock_t *ptl;
1108
	pte_t *start_pte;
1109
	pte_t *pte;
1110
	swp_entry_t entry;
K
KAMEZAWA Hiroyuki 已提交
1111

P
Peter Zijlstra 已提交
1112
again:
1113
	init_rss_vec(rss);
1114 1115
	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	pte = start_pte;
1116
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1117 1118
	do {
		pte_t ptent = *pte;
1119
		if (pte_none(ptent)) {
L
Linus Torvalds 已提交
1120
			continue;
1121
		}
1122

L
Linus Torvalds 已提交
1123
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
1124
			struct page *page;
1125

1126
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
1127 1128 1129 1130 1131 1132 1133 1134 1135 1136
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
				    details->check_mapping != page->mapping)
					continue;
			}
N
Nick Piggin 已提交
1137
			ptent = ptep_get_and_clear_full(mm, addr, pte,
1138
							tlb->fullmm);
L
Linus Torvalds 已提交
1139 1140 1141
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
1142 1143

			if (!PageAnon(page)) {
1144
				if (pte_dirty(ptent)) {
M
Michal Hocko 已提交
1145 1146 1147 1148 1149 1150
					/*
					 * oom_reaper cannot tear down dirty
					 * pages
					 */
					if (unlikely(details && details->ignore_dirty))
						continue;
1151
					force_flush = 1;
1152
					set_page_dirty(page);
1153
				}
1154
				if (pte_young(ptent) &&
1155
				    likely(!(vma->vm_flags & VM_SEQ_READ)))
1156
					mark_page_accessed(page);
1157
			}
1158
			rss[mm_counter(page)]--;
1159
			page_remove_rmap(page, false);
1160 1161
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
1162 1163
			if (unlikely(!__tlb_remove_page(tlb, page))) {
				force_flush = 1;
1164
				addr += PAGE_SIZE;
P
Peter Zijlstra 已提交
1165
				break;
1166
			}
L
Linus Torvalds 已提交
1167 1168
			continue;
		}
M
Michal Hocko 已提交
1169 1170
		/* only check swap_entries if explicitly asked for in details */
		if (unlikely(details && !details->check_swap_entries))
L
Linus Torvalds 已提交
1171
			continue;
K
KAMEZAWA Hiroyuki 已提交
1172

1173 1174 1175 1176 1177
		entry = pte_to_swp_entry(ptent);
		if (!non_swap_entry(entry))
			rss[MM_SWAPENTS]--;
		else if (is_migration_entry(entry)) {
			struct page *page;
1178

1179
			page = migration_entry_to_page(entry);
1180
			rss[mm_counter(page)]--;
K
KAMEZAWA Hiroyuki 已提交
1181
		}
1182 1183
		if (unlikely(!free_swap_and_cache(entry)))
			print_bad_pte(vma, addr, ptent, NULL);
1184
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1185
	} while (pte++, addr += PAGE_SIZE, addr != end);
1186

K
KAMEZAWA Hiroyuki 已提交
1187
	add_mm_rss_vec(mm, rss);
1188
	arch_leave_lazy_mmu_mode();
1189

1190
	/* Do the actual TLB flush before dropping ptl */
1191
	if (force_flush)
1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203
		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);
1204 1205

		if (addr != end)
P
Peter Zijlstra 已提交
1206 1207 1208
			goto again;
	}

1209
	return addr;
L
Linus Torvalds 已提交
1210 1211
}

1212
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1213
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
1214
				unsigned long addr, unsigned long end,
1215
				struct zap_details *details)
L
Linus Torvalds 已提交
1216 1217 1218 1219 1220 1221 1222
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1223
		if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1224
			if (next - addr != HPAGE_PMD_SIZE) {
1225 1226
				VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
				    !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1227
				split_huge_pmd(vma, pmd, addr);
S
Shaohua Li 已提交
1228
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1229
				goto next;
1230 1231
			/* fall through */
		}
1232 1233 1234 1235 1236 1237 1238 1239 1240
		/*
		 * 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;
1241
		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1242
next:
1243 1244
		cond_resched();
	} while (pmd++, addr = next, addr != end);
1245 1246

	return addr;
L
Linus Torvalds 已提交
1247 1248
}

1249
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1250
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1251
				unsigned long addr, unsigned long end,
1252
				struct zap_details *details)
L
Linus Torvalds 已提交
1253 1254 1255 1256 1257 1258 1259
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1260
		if (pud_none_or_clear_bad(pud))
L
Linus Torvalds 已提交
1261
			continue;
1262 1263
		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
	} while (pud++, addr = next, addr != end);
1264 1265

	return addr;
L
Linus Torvalds 已提交
1266 1267
}

M
Michal Hocko 已提交
1268
void unmap_page_range(struct mmu_gather *tlb,
A
Al Viro 已提交
1269 1270 1271
			     struct vm_area_struct *vma,
			     unsigned long addr, unsigned long end,
			     struct zap_details *details)
L
Linus Torvalds 已提交
1272 1273 1274 1275 1276 1277 1278 1279 1280
{
	pgd_t *pgd;
	unsigned long next;

	BUG_ON(addr >= end);
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
1281
		if (pgd_none_or_clear_bad(pgd))
L
Linus Torvalds 已提交
1282
			continue;
1283 1284
		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
	} while (pgd++, addr = next, addr != end);
L
Linus Torvalds 已提交
1285 1286
	tlb_end_vma(tlb, vma);
}
1287

1288 1289 1290

static void unmap_single_vma(struct mmu_gather *tlb,
		struct vm_area_struct *vma, unsigned long start_addr,
1291
		unsigned long end_addr,
1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302
		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;

1303 1304 1305
	if (vma->vm_file)
		uprobe_munmap(vma, start, end);

1306
	if (unlikely(vma->vm_flags & VM_PFNMAP))
1307
		untrack_pfn(vma, 0, 0);
1308 1309 1310 1311 1312 1313 1314

	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
1315
			 * cleanup path of mmap_region. When
1316
			 * hugetlbfs ->mmap method fails,
1317
			 * mmap_region() nullifies vma->vm_file
1318 1319 1320 1321
			 * before calling this function to clean up.
			 * Since no pte has actually been setup, it is
			 * safe to do nothing in this case.
			 */
1322
			if (vma->vm_file) {
1323
				i_mmap_lock_write(vma->vm_file->f_mapping);
1324
				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1325
				i_mmap_unlock_write(vma->vm_file->f_mapping);
1326
			}
1327 1328 1329
		} else
			unmap_page_range(tlb, vma, start, end, details);
	}
L
Linus Torvalds 已提交
1330 1331 1332 1333
}

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
1334
 * @tlb: address of the caller's struct mmu_gather
L
Linus Torvalds 已提交
1335 1336 1337 1338
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 *
1339
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1340 1341 1342 1343 1344 1345 1346 1347 1348 1349
 *
 * 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
1350
void unmap_vmas(struct mmu_gather *tlb,
L
Linus Torvalds 已提交
1351
		struct vm_area_struct *vma, unsigned long start_addr,
1352
		unsigned long end_addr)
L
Linus Torvalds 已提交
1353
{
A
Andrea Arcangeli 已提交
1354
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1355

A
Andrea Arcangeli 已提交
1356
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1357
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1358
		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
A
Andrea Arcangeli 已提交
1359
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1360 1361 1362 1363 1364
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
1365
 * @start: starting address of pages to zap
L
Linus Torvalds 已提交
1366
 * @size: number of bytes to zap
1367
 * @details: details of shared cache invalidation
1368 1369
 *
 * Caller must protect the VMA list
L
Linus Torvalds 已提交
1370
 */
1371
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
L
Linus Torvalds 已提交
1372 1373 1374
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1375
	struct mmu_gather tlb;
1376
	unsigned long end = start + size;
L
Linus Torvalds 已提交
1377 1378

	lru_add_drain();
1379
	tlb_gather_mmu(&tlb, mm, start, end);
1380
	update_hiwater_rss(mm);
1381 1382
	mmu_notifier_invalidate_range_start(mm, start, end);
	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1383
		unmap_single_vma(&tlb, vma, start, end, details);
1384 1385
	mmu_notifier_invalidate_range_end(mm, start, end);
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
1386 1387
}

1388 1389 1390 1391 1392
/**
 * 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
1393
 * @details: details of shared cache invalidation
1394 1395
 *
 * The range must fit into one VMA.
L
Linus Torvalds 已提交
1396
 */
1397
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1398 1399 1400
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1401
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1402 1403 1404
	unsigned long end = address + size;

	lru_add_drain();
1405
	tlb_gather_mmu(&tlb, mm, address, end);
1406
	update_hiwater_rss(mm);
1407
	mmu_notifier_invalidate_range_start(mm, address, end);
1408
	unmap_single_vma(&tlb, vma, address, end, details);
1409
	mmu_notifier_invalidate_range_end(mm, address, end);
P
Peter Zijlstra 已提交
1410
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1411 1412
}

1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430
/**
 * 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;
1431
	zap_page_range_single(vma, address, size, NULL);
1432 1433 1434 1435
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

1436
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
1437
			spinlock_t **ptl)
1438 1439 1440 1441
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1442
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1443 1444
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
1445
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1446
		}
1447 1448 1449 1450
	}
	return NULL;
}

1451 1452 1453 1454 1455 1456 1457
/*
 * 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
1458 1459
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1460
{
N
Nick Piggin 已提交
1461
	struct mm_struct *mm = vma->vm_mm;
1462
	int retval;
1463
	pte_t *pte;
1464 1465
	spinlock_t *ptl;

1466
	retval = -EINVAL;
1467
	if (PageAnon(page))
1468
		goto out;
1469 1470
	retval = -ENOMEM;
	flush_dcache_page(page);
1471
	pte = get_locked_pte(mm, addr, &ptl);
1472
	if (!pte)
1473
		goto out;
1474 1475 1476 1477 1478 1479
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
1480
	inc_mm_counter_fast(mm, mm_counter_file(page));
1481 1482 1483 1484
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1485 1486
	pte_unmap_unlock(pte, ptl);
	return retval;
1487 1488 1489 1490 1491 1492
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1493 1494 1495 1496 1497 1498
/**
 * 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
 *
1499 1500 1501 1502 1503 1504
 * 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
1505
 * (see split_page()).
1506 1507 1508 1509 1510 1511 1512 1513
 *
 * 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.
1514 1515 1516 1517 1518
 *
 * 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.
1519
 */
N
Nick Piggin 已提交
1520 1521
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1522 1523 1524 1525 1526
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1527 1528 1529 1530 1531
	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
1532
	return insert_page(vma, addr, page, vma->vm_page_prot);
1533
}
1534
EXPORT_SYMBOL(vm_insert_page);
1535

N
Nick Piggin 已提交
1536
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1537
			pfn_t pfn, pgprot_t prot)
N
Nick Piggin 已提交
1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552
{
	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.. */
1553 1554 1555 1556
	if (pfn_t_devmap(pfn))
		entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
	else
		entry = pte_mkspecial(pfn_t_pte(pfn, prot));
N
Nick Piggin 已提交
1557
	set_pte_at(mm, addr, pte, entry);
1558
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1559 1560 1561 1562 1563 1564 1565 1566

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

N
Nick Piggin 已提交
1567 1568 1569 1570 1571 1572
/**
 * 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
 *
1573
 * Similar to vm_insert_page, this allows drivers to insert individual pages
N
Nick Piggin 已提交
1574 1575 1576 1577
 * 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
1578 1579 1580 1581 1582
 *
 * 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
1583 1584
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1585
			unsigned long pfn)
A
Andy Lutomirski 已提交
1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607
{
	return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_insert_pfn);

/**
 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @pfn: source kernel pfn
 * @pgprot: pgprot flags for the inserted page
 *
 * This is exactly like vm_insert_pfn, except that it allows drivers to
 * to override pgprot on a per-page basis.
 *
 * This only makes sense for IO mappings, and it makes no sense for
 * cow mappings.  In general, using multiple vmas is preferable;
 * vm_insert_pfn_prot should only be used if using multiple VMAs is
 * impractical.
 */
int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn, pgprot_t pgprot)
N
Nick Piggin 已提交
1608
{
1609
	int ret;
N
Nick Piggin 已提交
1610 1611 1612 1613 1614 1615
	/*
	 * 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
1616 1617 1618 1619 1620
	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
1621

N
Nick Piggin 已提交
1622 1623
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1624
	if (track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)))
1625 1626
		return -EINVAL;

1627
	ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
1628 1629

	return ret;
N
Nick Piggin 已提交
1630
}
A
Andy Lutomirski 已提交
1631
EXPORT_SYMBOL(vm_insert_pfn_prot);
N
Nick Piggin 已提交
1632

N
Nick Piggin 已提交
1633
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1634
			pfn_t pfn)
N
Nick Piggin 已提交
1635 1636
{
	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
N
Nick Piggin 已提交
1637

N
Nick Piggin 已提交
1638 1639
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1640

N
Nick Piggin 已提交
1641 1642 1643 1644
	/*
	 * 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
1645 1646
	 * 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
1647
	 */
1648
	if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
N
Nick Piggin 已提交
1649 1650
		struct page *page;

1651 1652 1653 1654 1655 1656
		/*
		 * At this point we are committed to insert_page()
		 * regardless of whether the caller specified flags that
		 * result in pfn_t_has_page() == false.
		 */
		page = pfn_to_page(pfn_t_to_pfn(pfn));
N
Nick Piggin 已提交
1657 1658 1659
		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
1660
}
N
Nick Piggin 已提交
1661
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1662

L
Linus Torvalds 已提交
1663 1664 1665 1666 1667 1668 1669 1670 1671 1672
/*
 * 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
1673
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1674

H
Hugh Dickins 已提交
1675
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1676 1677
	if (!pte)
		return -ENOMEM;
1678
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1679 1680
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1681
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1682 1683
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1684
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1685
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699
	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;
1700
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729
	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;
}

1730 1731 1732 1733 1734 1735 1736 1737 1738 1739
/**
 * 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
1740 1741 1742 1743 1744
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;
1745
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1746 1747 1748 1749 1750 1751 1752 1753
	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).
1754 1755 1756
	 *   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.
1757 1758 1759 1760
	 *   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
1761 1762 1763 1764
	 *
	 * 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".
1765
	 * See vm_normal_page() for details.
L
Linus Torvalds 已提交
1766
	 */
1767 1768 1769
	if (is_cow_mapping(vma->vm_flags)) {
		if (addr != vma->vm_start || end != vma->vm_end)
			return -EINVAL;
L
Linus Torvalds 已提交
1770
		vma->vm_pgoff = pfn;
1771 1772 1773 1774
	}

	err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
	if (err)
1775
		return -EINVAL;
L
Linus Torvalds 已提交
1776

1777
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
L
Linus Torvalds 已提交
1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789

	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);
1790 1791

	if (err)
1792
		untrack_pfn(vma, pfn, PAGE_ALIGN(size));
1793

L
Linus Torvalds 已提交
1794 1795 1796 1797
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844
/**
 * 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);

1845 1846 1847 1848 1849 1850
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;
1851
	pgtable_t token;
1852
	spinlock_t *uninitialized_var(ptl);
1853 1854 1855 1856 1857 1858 1859 1860 1861

	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));

1862 1863
	arch_enter_lazy_mmu_mode();

1864
	token = pmd_pgtable(*pmd);
1865 1866

	do {
1867
		err = fn(pte++, token, addr, data);
1868 1869
		if (err)
			break;
1870
	} while (addr += PAGE_SIZE, addr != end);
1871

1872 1873
	arch_leave_lazy_mmu_mode();

1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886
	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
1887 1888
	BUG_ON(pud_huge(*pud));

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

1933 1934 1935
	if (WARN_ON(addr >= end))
		return -EINVAL;

1936 1937 1938 1939 1940 1941 1942
	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);
1943

1944 1945 1946 1947
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1948
/*
1949 1950 1951 1952 1953
 * 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;
1954
 * and do_anonymous_page can safely check later on).
1955
 */
H
Hugh Dickins 已提交
1956
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1957 1958 1959 1960 1961
				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
1962 1963
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1964
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1965
		spin_unlock(ptl);
1966 1967 1968 1969 1970 1971
	}
#endif
	pte_unmap(page_table);
	return same;
}

1972
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1973
{
1974 1975
	debug_dma_assert_idle(src);

1976 1977 1978 1979 1980 1981 1982
	/*
	 * 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)) {
1983
		void *kaddr = kmap_atomic(dst);
L
Linus Torvalds 已提交
1984 1985 1986 1987 1988 1989 1990 1991 1992
		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))
1993
			clear_page(kaddr);
1994
		kunmap_atomic(kaddr);
1995
		flush_dcache_page(dst);
N
Nick Piggin 已提交
1996 1997
	} else
		copy_user_highpage(dst, src, va, vma);
1998 1999
}

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
{
	struct file *vm_file = vma->vm_file;

	if (vm_file)
		return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;

	/*
	 * Special mappings (e.g. VDSO) do not have any file so fake
	 * a default GFP_KERNEL for them.
	 */
	return GFP_KERNEL;
}

2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028
/*
 * 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;
2029
	vmf.gfp_mask = __get_fault_gfp_mask(vma);
2030
	vmf.page = page;
2031
	vmf.cow_page = NULL;
2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047

	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;
}

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
/*
 * 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);
2090
		put_page(page);
2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106

		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;
}

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
/*
 * 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);
	}

2149
	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2150 2151
		goto oom_free_new;

2152 2153
	__SetPageUptodate(new_page);

2154 2155 2156 2157 2158 2159 2160 2161 2162
	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)) {
2163 2164
				dec_mm_counter_fast(mm,
						mm_counter_file(old_page));
2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179
				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);
2180
		page_add_new_anon_rmap(new_page, vma, address, false);
2181
		mem_cgroup_commit_charge(new_page, memcg, false, false);
2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212
		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.
			 */
2213
			page_remove_rmap(old_page, false);
2214 2215 2216 2217 2218 2219
		}

		/* Free the old page.. */
		new_page = old_page;
		page_copied = 1;
	} else {
2220
		mem_cgroup_cancel_charge(new_page, memcg, false);
2221 2222 2223
	}

	if (new_page)
2224
		put_page(new_page);
2225 2226 2227 2228 2229 2230 2231 2232 2233 2234

	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 */
2235 2236
			if (PageMlocked(old_page))
				munlock_vma_page(old_page);
2237 2238
			unlock_page(old_page);
		}
2239
		put_page(old_page);
2240 2241 2242
	}
	return page_copied ? VM_FAULT_WRITE : 0;
oom_free_new:
2243
	put_page(new_page);
2244 2245
oom:
	if (old_page)
2246
		put_page(old_page);
2247 2248 2249
	return VM_FAULT_OOM;
}

2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285
/*
 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
 * mapping
 */
static int wp_pfn_shared(struct mm_struct *mm,
			struct vm_area_struct *vma, unsigned long address,
			pte_t *page_table, spinlock_t *ptl, pte_t orig_pte,
			pmd_t *pmd)
{
	if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
		struct vm_fault vmf = {
			.page = NULL,
			.pgoff = linear_page_index(vma, address),
			.virtual_address = (void __user *)(address & PAGE_MASK),
			.flags = FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE,
		};
		int ret;

		pte_unmap_unlock(page_table, ptl);
		ret = vma->vm_ops->pfn_mkwrite(vma, &vmf);
		if (ret & VM_FAULT_ERROR)
			return ret;
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
		/*
		 * We might have raced with another page fault while we
		 * released the pte_offset_map_lock.
		 */
		if (!pte_same(*page_table, orig_pte)) {
			pte_unmap_unlock(page_table, ptl);
			return 0;
		}
	}
	return wp_page_reuse(mm, vma, address, page_table, ptl, orig_pte,
			     NULL, 0, 0);
}

2286 2287 2288 2289 2290 2291 2292 2293
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;

2294
	get_page(old_page);
2295 2296 2297 2298 2299 2300 2301 2302

	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)))) {
2303
			put_page(old_page);
2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316
			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);
2317
			put_page(old_page);
2318 2319 2320 2321 2322 2323 2324 2325 2326
			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
2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340
/*
 * 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.
 *
2341 2342 2343
 * 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
2344
 */
2345 2346
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2347
		spinlock_t *ptl, pte_t orig_pte)
2348
	__releases(ptl)
L
Linus Torvalds 已提交
2349
{
2350
	struct page *old_page;
L
Linus Torvalds 已提交
2351

2352
	old_page = vm_normal_page(vma, address, orig_pte);
2353 2354
	if (!old_page) {
		/*
2355 2356
		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
		 * VM_PFNMAP VMA.
2357 2358
		 *
		 * We should not cow pages in a shared writeable mapping.
2359
		 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2360 2361 2362
		 */
		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
				     (VM_WRITE|VM_SHARED))
2363 2364
			return wp_pfn_shared(mm, vma, address, page_table, ptl,
					     orig_pte, pmd);
2365 2366 2367 2368

		pte_unmap_unlock(page_table, ptl);
		return wp_page_copy(mm, vma, address, page_table, pmd,
				    orig_pte, old_page);
2369
	}
L
Linus Torvalds 已提交
2370

2371
	/*
P
Peter Zijlstra 已提交
2372 2373
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2374
	 */
H
Hugh Dickins 已提交
2375
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2376
		if (!trylock_page(old_page)) {
2377
			get_page(old_page);
2378 2379 2380 2381 2382 2383
			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);
2384
				pte_unmap_unlock(page_table, ptl);
2385
				put_page(old_page);
2386
				return 0;
2387
			}
2388
			put_page(old_page);
P
Peter Zijlstra 已提交
2389
		}
2390
		if (reuse_swap_page(old_page)) {
2391 2392 2393 2394 2395 2396
			/*
			 * 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);
2397
			unlock_page(old_page);
2398 2399
			return wp_page_reuse(mm, vma, address, page_table, ptl,
					     orig_pte, old_page, 0, 0);
2400
		}
2401
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2402
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2403
					(VM_WRITE|VM_SHARED))) {
2404 2405
		return wp_page_shared(mm, vma, address, page_table, pmd,
				      ptl, orig_pte, old_page);
L
Linus Torvalds 已提交
2406 2407 2408 2409 2410
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
2411
	get_page(old_page);
2412

2413
	pte_unmap_unlock(page_table, ptl);
2414 2415
	return wp_page_copy(mm, vma, address, page_table, pmd,
			    orig_pte, old_page);
L
Linus Torvalds 已提交
2416 2417
}

2418
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2419 2420 2421
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
2422
	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
L
Linus Torvalds 已提交
2423 2424
}

2425
static inline void unmap_mapping_range_tree(struct rb_root *root,
L
Linus Torvalds 已提交
2426 2427 2428 2429 2430
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	pgoff_t vba, vea, zba, zea;

2431
	vma_interval_tree_foreach(vma, root,
L
Linus Torvalds 已提交
2432 2433 2434
			details->first_index, details->last_index) {

		vba = vma->vm_pgoff;
2435
		vea = vba + vma_pages(vma) - 1;
L
Linus Torvalds 已提交
2436 2437 2438 2439 2440 2441 2442
		zba = details->first_index;
		if (zba < vba)
			zba = vba;
		zea = details->last_index;
		if (zea > vea)
			zea = vea;

2443
		unmap_mapping_range_vma(vma,
L
Linus Torvalds 已提交
2444 2445
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2446
				details);
L
Linus Torvalds 已提交
2447 2448 2449 2450
	}
}

/**
2451 2452 2453 2454
 * 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
2455
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2456 2457
 * @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
2458
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469
 * 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)
{
M
Michal Hocko 已提交
2470
	struct zap_details details = { };
L
Linus Torvalds 已提交
2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487
	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;

R
Ross Zwisler 已提交
2488 2489

	/* DAX uses i_mmap_lock to serialise file truncate vs page fault */
2490
	i_mmap_lock_write(mapping);
2491
	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
L
Linus Torvalds 已提交
2492
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
2493
	i_mmap_unlock_write(mapping);
L
Linus Torvalds 已提交
2494 2495 2496 2497
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
2498 2499
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
2500 2501 2502 2503
 * 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
2504
 */
2505 2506
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2507
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2508
{
2509
	spinlock_t *ptl;
2510
	struct page *page, *swapcache;
2511
	struct mem_cgroup *memcg;
2512
	swp_entry_t entry;
L
Linus Torvalds 已提交
2513
	pte_t pte;
2514
	int locked;
2515
	int exclusive = 0;
N
Nick Piggin 已提交
2516
	int ret = 0;
L
Linus Torvalds 已提交
2517

H
Hugh Dickins 已提交
2518
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2519
		goto out;
2520 2521

	entry = pte_to_swp_entry(orig_pte);
2522 2523 2524 2525 2526 2527 2528
	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
2529
			ret = VM_FAULT_SIGBUS;
2530
		}
2531 2532
		goto out;
	}
2533
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2534 2535
	page = lookup_swap_cache(entry);
	if (!page) {
2536 2537
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2538 2539
		if (!page) {
			/*
2540 2541
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2542
			 */
2543
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2544 2545
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2546
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2547
			goto unlock;
L
Linus Torvalds 已提交
2548 2549 2550 2551
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2552
		count_vm_event(PGMAJFAULT);
2553
		mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2554
	} else if (PageHWPoison(page)) {
2555 2556 2557 2558
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2559 2560
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2561
		swapcache = page;
2562
		goto out_release;
L
Linus Torvalds 已提交
2563 2564
	}

2565
	swapcache = page;
2566
	locked = lock_page_or_retry(page, mm, flags);
R
Rik van Riel 已提交
2567

2568
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2569 2570 2571 2572
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2573

A
Andrea Arcangeli 已提交
2574
	/*
2575 2576 2577 2578
	 * 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
2579
	 */
2580
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2581 2582
		goto out_page;

2583 2584 2585 2586 2587
	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
2588 2589
	}

2590
	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg, false)) {
2591
		ret = VM_FAULT_OOM;
2592
		goto out_page;
2593 2594
	}

L
Linus Torvalds 已提交
2595
	/*
2596
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2597
	 */
2598
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2599
	if (unlikely(!pte_same(*page_table, orig_pte)))
2600 2601 2602 2603 2604
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2605 2606
	}

2607 2608 2609 2610 2611 2612 2613 2614 2615
	/*
	 * 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
2616

2617
	inc_mm_counter_fast(mm, MM_ANONPAGES);
K
KAMEZAWA Hiroyuki 已提交
2618
	dec_mm_counter_fast(mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
2619
	pte = mk_pte(page, vma->vm_page_prot);
2620
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2621
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2622
		flags &= ~FAULT_FLAG_WRITE;
2623
		ret |= VM_FAULT_WRITE;
2624
		exclusive = RMAP_EXCLUSIVE;
L
Linus Torvalds 已提交
2625 2626
	}
	flush_icache_page(vma, page);
2627 2628
	if (pte_swp_soft_dirty(orig_pte))
		pte = pte_mksoft_dirty(pte);
L
Linus Torvalds 已提交
2629
	set_pte_at(mm, address, page_table, pte);
2630
	if (page == swapcache) {
2631
		do_page_add_anon_rmap(page, vma, address, exclusive);
2632
		mem_cgroup_commit_charge(page, memcg, true, false);
2633
	} else { /* ksm created a completely new copy */
2634
		page_add_new_anon_rmap(page, vma, address, false);
2635
		mem_cgroup_commit_charge(page, memcg, false, false);
2636 2637
		lru_cache_add_active_or_unevictable(page, vma);
	}
L
Linus Torvalds 已提交
2638

2639
	swap_free(entry);
2640 2641
	if (mem_cgroup_swap_full(page) ||
	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2642
		try_to_free_swap(page);
2643
	unlock_page(page);
2644
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2645 2646 2647 2648 2649 2650 2651 2652 2653
		/*
		 * 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);
2654
		put_page(swapcache);
A
Andrea Arcangeli 已提交
2655
	}
2656

2657
	if (flags & FAULT_FLAG_WRITE) {
2658 2659 2660
		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
2661 2662 2663 2664
		goto out;
	}

	/* No need to invalidate - it was non-present before */
2665
	update_mmu_cache(vma, address, page_table);
2666
unlock:
2667
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2668 2669
out:
	return ret;
2670
out_nomap:
2671
	mem_cgroup_cancel_charge(page, memcg, false);
2672
	pte_unmap_unlock(page_table, ptl);
2673
out_page:
2674
	unlock_page(page);
2675
out_release:
2676
	put_page(page);
2677
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2678
		unlock_page(swapcache);
2679
		put_page(swapcache);
A
Andrea Arcangeli 已提交
2680
	}
2681
	return ret;
L
Linus Torvalds 已提交
2682 2683
}

2684
/*
2685 2686
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2687 2688 2689 2690 2691 2692
 * 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) {
2693 2694 2695 2696 2697 2698 2699 2700 2701 2702
		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;
2703

2704
		return expand_downwards(vma, address - PAGE_SIZE);
2705
	}
2706 2707 2708 2709 2710 2711 2712
	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;

2713
		return expand_upwards(vma, address + PAGE_SIZE);
2714
	}
2715 2716 2717
	return 0;
}

L
Linus Torvalds 已提交
2718
/*
2719 2720 2721
 * 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
2722
 */
2723 2724
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2725
		unsigned int flags)
L
Linus Torvalds 已提交
2726
{
2727
	struct mem_cgroup *memcg;
2728 2729
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2730 2731
	pte_t entry;

2732 2733
	pte_unmap(page_table);

2734 2735 2736 2737
	/* File mapping without ->vm_ops ? */
	if (vma->vm_flags & VM_SHARED)
		return VM_FAULT_SIGBUS;

2738 2739
	/* Check if we need to add a guard page to the stack */
	if (check_stack_guard_page(vma, address) < 0)
2740
		return VM_FAULT_SIGSEGV;
2741

2742
	/* Use the zero-page for reads */
2743
	if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
H
Hugh Dickins 已提交
2744 2745
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
2746
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2747 2748
		if (!pte_none(*page_table))
			goto unlock;
2749 2750 2751 2752 2753 2754
		/* Deliver the page fault to userland, check inside PT lock */
		if (userfaultfd_missing(vma)) {
			pte_unmap_unlock(page_table, ptl);
			return handle_userfault(vma, address, flags,
						VM_UFFD_MISSING);
		}
H
Hugh Dickins 已提交
2755 2756 2757
		goto setpte;
	}

N
Nick Piggin 已提交
2758 2759 2760 2761 2762 2763
	/* 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;
2764

2765
	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg, false))
2766 2767
		goto oom_free_page;

2768 2769 2770 2771 2772
	/*
	 * 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
2773
	__SetPageUptodate(page);
2774

N
Nick Piggin 已提交
2775
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
2776 2777
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
2778

N
Nick Piggin 已提交
2779
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2780
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
2781
		goto release;
H
Hugh Dickins 已提交
2782

2783 2784 2785
	/* Deliver the page fault to userland, check inside PT lock */
	if (userfaultfd_missing(vma)) {
		pte_unmap_unlock(page_table, ptl);
2786
		mem_cgroup_cancel_charge(page, memcg, false);
2787
		put_page(page);
2788 2789 2790 2791
		return handle_userfault(vma, address, flags,
					VM_UFFD_MISSING);
	}

2792
	inc_mm_counter_fast(mm, MM_ANONPAGES);
2793
	page_add_new_anon_rmap(page, vma, address, false);
2794
	mem_cgroup_commit_charge(page, memcg, false, false);
2795
	lru_cache_add_active_or_unevictable(page, vma);
H
Hugh Dickins 已提交
2796
setpte:
2797
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
2798 2799

	/* No need to invalidate - it was non-present before */
2800
	update_mmu_cache(vma, address, page_table);
2801
unlock:
2802
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
2803
	return 0;
2804
release:
2805
	mem_cgroup_cancel_charge(page, memcg, false);
2806
	put_page(page);
2807
	goto unlock;
2808
oom_free_page:
2809
	put_page(page);
2810
oom:
L
Linus Torvalds 已提交
2811 2812 2813
	return VM_FAULT_OOM;
}

2814 2815 2816 2817 2818
/*
 * 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().
 */
2819
static int __do_fault(struct vm_area_struct *vma, unsigned long address,
2820 2821
			pgoff_t pgoff, unsigned int flags,
			struct page *cow_page, struct page **page)
2822 2823 2824 2825 2826 2827 2828 2829
{
	struct vm_fault vmf;
	int ret;

	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
2830
	vmf.gfp_mask = __get_fault_gfp_mask(vma);
2831
	vmf.cow_page = cow_page;
2832 2833 2834 2835

	ret = vma->vm_ops->fault(vma, &vmf);
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		return ret;
2836 2837
	if (!vmf.page)
		goto out;
2838 2839 2840 2841

	if (unlikely(PageHWPoison(vmf.page))) {
		if (ret & VM_FAULT_LOCKED)
			unlock_page(vmf.page);
2842
		put_page(vmf.page);
2843 2844 2845 2846 2847 2848 2849 2850
		return VM_FAULT_HWPOISON;
	}

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

2851
 out:
2852 2853 2854 2855
	*page = vmf.page;
	return ret;
}

2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871
/**
 * 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,
2872 2873 2874 2875 2876 2877 2878 2879 2880 2881
		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);
2882
		page_add_new_anon_rmap(page, vma, address, false);
2883
	} else {
2884
		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
2885 2886 2887 2888 2889 2890 2891 2892
		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);
}

2893 2894
static unsigned long fault_around_bytes __read_mostly =
	rounddown_pow_of_two(65536);
2895 2896 2897

#ifdef CONFIG_DEBUG_FS
static int fault_around_bytes_get(void *data, u64 *val)
2898
{
2899
	*val = fault_around_bytes;
2900 2901 2902
	return 0;
}

2903 2904 2905 2906 2907
/*
 * 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.
 */
2908
static int fault_around_bytes_set(void *data, u64 val)
2909
{
2910
	if (val / PAGE_SIZE > PTRS_PER_PTE)
2911
		return -EINVAL;
2912 2913 2914 2915
	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 */
2916 2917
	return 0;
}
2918 2919
DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
		fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
2920 2921 2922 2923 2924

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

2925 2926
	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
			&fault_around_bytes_fops);
2927
	if (!ret)
2928
		pr_warn("Failed to create fault_around_bytes in debugfs");
2929 2930 2931 2932
	return 0;
}
late_initcall(fault_around_debugfs);
#endif
2933

2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956
/*
 * 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.
 */
2957 2958 2959
static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
		pte_t *pte, pgoff_t pgoff, unsigned int flags)
{
2960
	unsigned long start_addr, nr_pages, mask;
2961 2962 2963 2964
	pgoff_t max_pgoff;
	struct vm_fault vmf;
	int off;

2965
	nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
2966 2967 2968
	mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;

	start_addr = max(address & mask, vma->vm_start);
2969 2970 2971 2972 2973 2974
	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
2975
	 *  or fault_around_pages() from pgoff, depending what is nearest.
2976 2977 2978 2979
	 */
	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,
2980
			pgoff + nr_pages - 1);
2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996

	/* 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;
2997
	vmf.gfp_mask = __get_fault_gfp_mask(vma);
2998 2999 3000
	vma->vm_ops->map_pages(vma, &vmf);
}

3001 3002 3003 3004 3005 3006
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;
3007
	pte_t *pte;
3008 3009 3010 3011 3012 3013 3014
	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).
	 */
3015
	if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3016 3017 3018 3019 3020 3021
		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);
	}
3022

3023
	ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
3024 3025 3026 3027 3028 3029 3030
	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);
3031
		put_page(fault_page);
3032 3033
		return ret;
	}
3034
	do_set_pte(vma, address, fault_page, pte, false, false);
3035
	unlock_page(fault_page);
3036 3037
unlock_out:
	pte_unmap_unlock(pte, ptl);
3038 3039 3040
	return ret;
}

3041 3042 3043 3044 3045
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;
3046
	struct mem_cgroup *memcg;
3047
	spinlock_t *ptl;
3048
	pte_t *pte;
3049 3050 3051 3052 3053 3054 3055 3056 3057
	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;

3058
	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false)) {
3059
		put_page(new_page);
3060 3061 3062
		return VM_FAULT_OOM;
	}

3063
	ret = __do_fault(vma, address, pgoff, flags, new_page, &fault_page);
3064 3065 3066
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		goto uncharge_out;

3067 3068
	if (fault_page)
		copy_user_highpage(new_page, fault_page, address, vma);
3069 3070 3071 3072 3073
	__SetPageUptodate(new_page);

	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
	if (unlikely(!pte_same(*pte, orig_pte))) {
		pte_unmap_unlock(pte, ptl);
3074 3075
		if (fault_page) {
			unlock_page(fault_page);
3076
			put_page(fault_page);
3077 3078 3079
		} else {
			/*
			 * The fault handler has no page to lock, so it holds
3080
			 * i_mmap_lock for read to protect against truncate.
3081
			 */
3082
			i_mmap_unlock_read(vma->vm_file->f_mapping);
3083
		}
3084 3085
		goto uncharge_out;
	}
3086
	do_set_pte(vma, address, new_page, pte, true, true);
3087
	mem_cgroup_commit_charge(new_page, memcg, false, false);
3088
	lru_cache_add_active_or_unevictable(new_page, vma);
3089
	pte_unmap_unlock(pte, ptl);
3090 3091
	if (fault_page) {
		unlock_page(fault_page);
3092
		put_page(fault_page);
3093 3094 3095
	} else {
		/*
		 * The fault handler has no page to lock, so it holds
3096
		 * i_mmap_lock for read to protect against truncate.
3097
		 */
3098
		i_mmap_unlock_read(vma->vm_file->f_mapping);
3099
	}
3100 3101
	return ret;
uncharge_out:
3102
	mem_cgroup_cancel_charge(new_page, memcg, false);
3103
	put_page(new_page);
3104 3105 3106
	return ret;
}

3107
static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3108
		unsigned long address, pmd_t *pmd,
3109
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3110
{
3111 3112
	struct page *fault_page;
	struct address_space *mapping;
3113
	spinlock_t *ptl;
3114
	pte_t *pte;
3115 3116
	int dirtied = 0;
	int ret, tmp;
3117

3118
	ret = __do_fault(vma, address, pgoff, flags, NULL, &fault_page);
3119
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3120
		return ret;
L
Linus Torvalds 已提交
3121 3122

	/*
3123 3124
	 * Check if the backing address space wants to know that the page is
	 * about to become writable
L
Linus Torvalds 已提交
3125
	 */
3126 3127 3128 3129 3130
	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)))) {
3131
			put_page(fault_page);
3132
			return tmp;
3133
		}
3134 3135
	}

3136 3137 3138 3139
	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);
3140
		put_page(fault_page);
3141
		return ret;
L
Linus Torvalds 已提交
3142
	}
3143
	do_set_pte(vma, address, fault_page, pte, true, false);
3144
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3145

3146 3147
	if (set_page_dirty(fault_page))
		dirtied = 1;
3148 3149 3150 3151 3152 3153
	/*
	 * 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.
	 */
3154
	mapping = page_rmapping(fault_page);
3155 3156 3157 3158 3159 3160 3161
	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);
3162
	}
3163

3164
	if (!vma->vm_ops->page_mkwrite)
3165
		file_update_time(vma->vm_file);
N
Nick Piggin 已提交
3166

3167
	return ret;
3168
}
3169

3170 3171 3172 3173 3174 3175
/*
 * 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().
 */
3176
static int do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3177
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3178
		unsigned int flags, pte_t orig_pte)
3179
{
3180
	pgoff_t pgoff = linear_page_index(vma, address);
3181

3182
	pte_unmap(page_table);
3183 3184 3185
	/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
	if (!vma->vm_ops->fault)
		return VM_FAULT_SIGBUS;
3186 3187 3188
	if (!(flags & FAULT_FLAG_WRITE))
		return do_read_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3189 3190 3191
	if (!(vma->vm_flags & VM_SHARED))
		return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
				orig_pte);
3192
	return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3193 3194
}

3195
static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3196 3197
				unsigned long addr, int page_nid,
				int *flags)
3198 3199 3200 3201
{
	get_page(page);

	count_vm_numa_event(NUMA_HINT_FAULTS);
3202
	if (page_nid == numa_node_id()) {
3203
		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3204 3205
		*flags |= TNF_FAULT_LOCAL;
	}
3206 3207 3208 3209

	return mpol_misplaced(page, vma, addr);
}

3210
static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3211 3212
		   unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
{
3213
	struct page *page = NULL;
3214
	spinlock_t *ptl;
3215
	int page_nid = -1;
3216
	int last_cpupid;
3217
	int target_nid;
3218
	bool migrated = false;
3219
	bool was_writable = pte_write(pte);
3220
	int flags = 0;
3221

3222 3223 3224
	/* A PROT_NONE fault should not end up here */
	BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));

3225 3226 3227 3228 3229
	/*
	* 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.
	*
3230 3231 3232
	* 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.
3233 3234 3235
	*/
	ptl = pte_lockptr(mm, pmd);
	spin_lock(ptl);
3236 3237 3238 3239 3240
	if (unlikely(!pte_same(*ptep, pte))) {
		pte_unmap_unlock(ptep, ptl);
		goto out;
	}

3241 3242 3243
	/* Make it present again */
	pte = pte_modify(pte, vma->vm_page_prot);
	pte = pte_mkyoung(pte);
3244 3245
	if (was_writable)
		pte = pte_mkwrite(pte);
3246 3247 3248 3249 3250 3251 3252 3253 3254
	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;
	}

3255 3256 3257 3258 3259 3260
	/* TODO: handle PTE-mapped THP */
	if (PageCompound(page)) {
		pte_unmap_unlock(ptep, ptl);
		return 0;
	}

3261
	/*
3262 3263 3264 3265 3266 3267
	 * 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.
3268
	 */
3269
	if (!(vma->vm_flags & VM_WRITE))
3270 3271
		flags |= TNF_NO_GROUP;

3272 3273 3274 3275 3276 3277 3278
	/*
	 * 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;

3279
	last_cpupid = page_cpupid_last(page);
3280
	page_nid = page_to_nid(page);
3281
	target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3282
	pte_unmap_unlock(ptep, ptl);
3283 3284 3285 3286 3287 3288
	if (target_nid == -1) {
		put_page(page);
		goto out;
	}

	/* Migrate to the requested node */
3289
	migrated = migrate_misplaced_page(page, vma, target_nid);
3290
	if (migrated) {
3291
		page_nid = target_nid;
3292
		flags |= TNF_MIGRATED;
3293 3294
	} else
		flags |= TNF_MIGRATE_FAIL;
3295 3296

out:
3297
	if (page_nid != -1)
3298
		task_numa_fault(last_cpupid, page_nid, 1, flags);
3299 3300 3301
	return 0;
}

M
Matthew Wilcox 已提交
3302 3303 3304
static int create_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
			unsigned long address, pmd_t *pmd, unsigned int flags)
{
3305
	if (vma_is_anonymous(vma))
M
Matthew Wilcox 已提交
3306 3307 3308 3309 3310 3311 3312 3313 3314 3315
		return do_huge_pmd_anonymous_page(mm, vma, address, pmd, flags);
	if (vma->vm_ops->pmd_fault)
		return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
	return VM_FAULT_FALLBACK;
}

static int wp_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
			unsigned long address, pmd_t *pmd, pmd_t orig_pmd,
			unsigned int flags)
{
3316
	if (vma_is_anonymous(vma))
M
Matthew Wilcox 已提交
3317 3318 3319 3320 3321 3322
		return do_huge_pmd_wp_page(mm, vma, address, pmd, orig_pmd);
	if (vma->vm_ops->pmd_fault)
		return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
	return VM_FAULT_FALLBACK;
}

L
Linus Torvalds 已提交
3323 3324 3325 3326 3327 3328 3329 3330 3331
/*
 * 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
3332 3333
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
3334 3335 3336 3337
 * 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
3338
 */
3339
static int handle_pte_fault(struct mm_struct *mm,
3340 3341
		     struct vm_area_struct *vma, unsigned long address,
		     pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
3342 3343
{
	pte_t entry;
3344
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3345

3346 3347 3348 3349 3350 3351 3352 3353 3354 3355
	/*
	 * 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
3356
	if (!pte_present(entry)) {
3357
		if (pte_none(entry)) {
3358 3359 3360 3361
			if (vma_is_anonymous(vma))
				return do_anonymous_page(mm, vma, address,
							 pte, pmd, flags);
			else
3362 3363
				return do_fault(mm, vma, address, pte, pmd,
						flags, entry);
3364 3365
		}
		return do_swap_page(mm, vma, address,
3366
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
3367 3368
	}

3369
	if (pte_protnone(entry))
3370 3371
		return do_numa_page(mm, vma, address, entry, pte, pmd);

H
Hugh Dickins 已提交
3372
	ptl = pte_lockptr(mm, pmd);
3373 3374 3375
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
3376
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3377
		if (!pte_write(entry))
3378 3379
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
3380 3381 3382
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
3383
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3384
		update_mmu_cache(vma, address, pte);
3385 3386 3387 3388 3389 3390 3391
	} 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.
		 */
3392
		if (flags & FAULT_FLAG_WRITE)
3393
			flush_tlb_fix_spurious_fault(vma, address);
3394
	}
3395 3396
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3397
	return 0;
L
Linus Torvalds 已提交
3398 3399 3400 3401
}

/*
 * By the time we get here, we already hold the mm semaphore
3402 3403 3404
 *
 * 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
3405
 */
3406 3407
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
3408 3409 3410 3411 3412 3413
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

3414
	if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3415
					    flags & FAULT_FLAG_INSTRUCTION,
3416
					    flags & FAULT_FLAG_REMOTE))
3417 3418
		return VM_FAULT_SIGSEGV;

3419
	if (unlikely(is_vm_hugetlb_page(vma)))
3420
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3421 3422 3423 3424

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3425
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3426 3427
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3428
		return VM_FAULT_OOM;
3429
	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
M
Matthew Wilcox 已提交
3430
		int ret = create_huge_pmd(mm, vma, address, pmd, flags);
3431 3432
		if (!(ret & VM_FAULT_FALLBACK))
			return ret;
3433 3434
	} else {
		pmd_t orig_pmd = *pmd;
3435 3436
		int ret;

3437
		barrier();
3438
		if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3439 3440
			unsigned int dirty = flags & FAULT_FLAG_WRITE;

3441
			if (pmd_protnone(orig_pmd))
3442
				return do_huge_pmd_numa_page(mm, vma, address,
3443 3444
							     orig_pmd, pmd);

3445
			if (dirty && !pmd_write(orig_pmd)) {
M
Matthew Wilcox 已提交
3446 3447
				ret = wp_huge_pmd(mm, vma, address, pmd,
							orig_pmd, flags);
3448 3449
				if (!(ret & VM_FAULT_FALLBACK))
					return ret;
3450 3451 3452
			} else {
				huge_pmd_set_accessed(mm, vma, address, pmd,
						      orig_pmd, dirty);
3453
				return 0;
3454
			}
3455 3456 3457 3458
		}
	}

	/*
3459
	 * Use pte_alloc() instead of pte_alloc_map, because we can't
3460 3461 3462
	 * run pte_offset_map on the pmd, if an huge pmd could
	 * materialize from under us from a different thread.
	 */
3463
	if (unlikely(pte_alloc(mm, pmd, address)))
H
Hugh Dickins 已提交
3464
		return VM_FAULT_OOM;
3465 3466 3467 3468 3469 3470 3471 3472 3473 3474 3475 3476
	/*
	 * If a huge pmd materialized under us just retry later.  Use
	 * pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd
	 * didn't become pmd_trans_huge under us and then back to pmd_none, as
	 * a result of MADV_DONTNEED running immediately after a huge pmd fault
	 * in a different thread of this mm, in turn leading to a misleading
	 * pmd_trans_huge() retval.  All we have to ensure is that it is a
	 * regular pmd that we can walk with pte_offset_map() and we can do that
	 * through an atomic read in C, which is what pmd_trans_unstable()
	 * provides.
	 */
	if (unlikely(pmd_trans_unstable(pmd) || pmd_devmap(*pmd)))
3477 3478 3479 3480 3481 3482 3483 3484
		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
3485

3486
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3487 3488
}

3489 3490 3491 3492 3493 3494
/*
 * 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().
 */
3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512
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)
3513
		mem_cgroup_oom_enable();
3514 3515 3516

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

3517 3518 3519 3520 3521 3522 3523 3524 3525 3526 3527
	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);
	}
3528

3529 3530
	return ret;
}
3531
EXPORT_SYMBOL_GPL(handle_mm_fault);
3532

L
Linus Torvalds 已提交
3533 3534 3535
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3536
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3537
 */
3538
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3539
{
H
Hugh Dickins 已提交
3540 3541
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3542
		return -ENOMEM;
L
Linus Torvalds 已提交
3543

3544 3545
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3546
	spin_lock(&mm->page_table_lock);
3547
	if (pgd_present(*pgd))		/* Another has populated it */
3548
		pud_free(mm, new);
3549 3550
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3551
	spin_unlock(&mm->page_table_lock);
3552
	return 0;
L
Linus Torvalds 已提交
3553 3554 3555 3556 3557 3558
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3559
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3560
 */
3561
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3562
{
H
Hugh Dickins 已提交
3563 3564
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3565
		return -ENOMEM;
L
Linus Torvalds 已提交
3566

3567 3568
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3569
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3570
#ifndef __ARCH_HAS_4LEVEL_HACK
3571 3572
	if (!pud_present(*pud)) {
		mm_inc_nr_pmds(mm);
3573
		pud_populate(mm, pud, new);
3574
	} else	/* Another has populated it */
3575
		pmd_free(mm, new);
3576 3577 3578
#else
	if (!pgd_present(*pud)) {
		mm_inc_nr_pmds(mm);
3579
		pgd_populate(mm, pud, new);
3580 3581
	} else /* Another has populated it */
		pmd_free(mm, new);
L
Linus Torvalds 已提交
3582
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3583
	spin_unlock(&mm->page_table_lock);
3584
	return 0;
3585
}
L
Linus Torvalds 已提交
3586 3587
#endif /* __PAGETABLE_PMD_FOLDED */

3588
static int __follow_pte(struct mm_struct *mm, unsigned long address,
J
Johannes Weiner 已提交
3589 3590 3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604
		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);
3605
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3606 3607 3608 3609 3610 3611 3612 3613 3614 3615 3616 3617 3618 3619 3620 3621 3622 3623 3624 3625
	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;
}

3626 3627 3628 3629 3630 3631 3632 3633 3634 3635 3636
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
3637 3638 3639 3640 3641 3642 3643 3644 3645 3646 3647 3648 3649 3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660 3661 3662 3663 3664 3665
/**
 * 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);

3666
#ifdef CONFIG_HAVE_IOREMAP_PROT
3667 3668 3669
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3670
{
3671
	int ret = -EINVAL;
3672 3673 3674
	pte_t *ptep, pte;
	spinlock_t *ptl;

3675 3676
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3677

3678
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3679
		goto out;
3680
	pte = *ptep;
3681

3682 3683 3684 3685
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3686
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3687

3688
	ret = 0;
3689 3690 3691
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3692
	return ret;
3693 3694 3695 3696 3697 3698 3699
}

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
3700
	void __iomem *maddr;
3701 3702
	int offset = addr & (PAGE_SIZE-1);

3703
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3704 3705
		return -EINVAL;

3706
	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
3707 3708 3709 3710 3711 3712 3713 3714
	if (write)
		memcpy_toio(maddr + offset, buf, len);
	else
		memcpy_fromio(buf, maddr + offset, len);
	iounmap(maddr);

	return len;
}
3715
EXPORT_SYMBOL_GPL(generic_access_phys);
3716 3717
#endif

3718
/*
3719 3720
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
3721
 */
3722 3723
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long addr, void *buf, int len, int write)
3724 3725 3726 3727 3728
{
	struct vm_area_struct *vma;
	void *old_buf = buf;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3729
	/* ignore errors, just check how much was successfully transferred */
3730 3731 3732
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3733
		struct page *page = NULL;
3734

3735
		ret = get_user_pages_remote(tsk, mm, addr, 1,
3736
				write, 1, &page, &vma);
3737
		if (ret <= 0) {
3738 3739 3740
#ifndef CONFIG_HAVE_IOREMAP_PROT
			break;
#else
3741 3742 3743 3744 3745
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
			vma = find_vma(mm, addr);
3746
			if (!vma || vma->vm_start > addr)
3747 3748 3749 3750 3751 3752 3753
				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;
3754
#endif
3755
		} else {
3756 3757 3758 3759 3760 3761 3762 3763 3764 3765 3766 3767 3768 3769 3770
			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);
3771
			put_page(page);
3772 3773 3774 3775 3776 3777 3778 3779 3780
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
3781

S
Stephen Wilson 已提交
3782
/**
3783
 * access_remote_vm - access another process' address space
S
Stephen Wilson 已提交
3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796 3797
 * @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);
}

3798 3799 3800 3801 3802 3803 3804 3805 3806 3807 3808 3809 3810 3811 3812 3813 3814 3815 3816 3817 3818
/*
 * 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;
}

3819 3820 3821 3822 3823 3824 3825 3826
/*
 * 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;

3827 3828 3829 3830 3831 3832 3833
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3834 3835 3836 3837 3838 3839
	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
3840
			char *p;
3841

M
Miklos Szeredi 已提交
3842
			p = file_path(f, buf, PAGE_SIZE);
3843 3844
			if (IS_ERR(p))
				p = "?";
A
Andy Shevchenko 已提交
3845
			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
3846 3847 3848 3849 3850
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
3851
	up_read(&mm->mmap_sem);
3852
}
3853

3854
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3855
void __might_fault(const char *file, int line)
3856
{
3857 3858 3859 3860 3861 3862 3863 3864
	/*
	 * 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;
3865
	if (pagefault_disabled())
3866
		return;
3867 3868
	__might_sleep(file, line, 0);
#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
3869
	if (current->mm)
3870
		might_lock_read(&current->mm->mmap_sem);
3871
#endif
3872
}
3873
EXPORT_SYMBOL(__might_fault);
3874
#endif
A
Andrea Arcangeli 已提交
3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892 3893 3894 3895 3896 3897 3898 3899 3900 3901 3902 3903 3904 3905 3906 3907 3908 3909 3910 3911 3912 3913 3914 3915 3916 3917 3918 3919 3920 3921 3922 3923 3924 3925 3926 3927 3928 3929 3930 3931 3932 3933 3934 3935 3936 3937 3938 3939 3940 3941 3942 3943 3944 3945

#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 */
3946

3947
#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
3948 3949 3950 3951 3952 3953 3954 3955 3956

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);
}

3957
bool ptlock_alloc(struct page *page)
3958 3959 3960
{
	spinlock_t *ptl;

3961
	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
3962 3963
	if (!ptl)
		return false;
3964
	page->ptl = ptl;
3965 3966 3967
	return true;
}

3968
void ptlock_free(struct page *page)
3969
{
3970
	kmem_cache_free(page_ptl_cachep, page->ptl);
3971 3972
}
#endif