memory.c 111.9 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

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

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

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

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

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/export.h>
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#include <linux/delayacct.h>
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#include <linux/init.h>
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#include <linux/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 <linux/dax.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->page_size = 0;
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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().
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 *returns true if the caller should flush.
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 */
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bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
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{
	struct mmu_gather_batch *batch;

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	VM_BUG_ON(!tlb->end);
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	VM_WARN_ON(tlb->page_size != page_size);
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	batch = tlb->active;
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	/*
	 * Add the page and check if we are full. If so
	 * force a flush.
	 */
	batch->pages[batch->nr++] = page;
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	if (batch->nr == batch->max) {
		if (!tlb_next_batch(tlb))
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			return true;
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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 false;
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}

#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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	/*
	 * We add page table cache pages with PAGE_SIZE,
	 * (see pte_free_tlb()), flush the tlb if we need
	 */
	tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
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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 */

620
	spin_lock(&init_mm.page_table_lock);
621
	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
622
		pmd_populate_kernel(&init_mm, pmd, new);
623
		new = NULL;
624
	}
625
	spin_unlock(&init_mm.page_table_lock);
626 627
	if (new)
		pte_free_kernel(&init_mm, new);
628
	return 0;
L
Linus Torvalds 已提交
629 630
}

K
KAMEZAWA Hiroyuki 已提交
631 632 633 634 635 636
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)
637
{
K
KAMEZAWA Hiroyuki 已提交
638 639
	int i;

640
	if (current->mm == mm)
641
		sync_mm_rss(mm);
K
KAMEZAWA Hiroyuki 已提交
642 643 644
	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
645 646
}

N
Nick Piggin 已提交
647
/*
648 649 650
 * 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
651 652 653
 *
 * The calling function must still handle the error.
 */
654 655
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
656
{
657 658 659 660 661
	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;
662 663 664 665 666 667 668 669 670 671 672 673 674 675
	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) {
676 677
			pr_alert("BUG: Bad page map: %lu messages suppressed\n",
				 nr_unshown);
678 679 680 681 682 683
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
684 685 686 687

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

688 689 690
	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));
691
	if (page)
692
		dump_page(page, "bad pte");
693 694
	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);
695 696 697
	/*
	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
	 */
698 699 700 701 702
	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
703
	dump_stack();
704
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
N
Nick Piggin 已提交
705 706
}

H
Hugh Dickins 已提交
707
/*
N
Nick Piggin 已提交
708
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
709
 *
N
Nick Piggin 已提交
710 711 712
 * "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
713
 *
N
Nick Piggin 已提交
714 715 716 717 718 719 720 721
 * 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.
722
 *
J
Jared Hulbert 已提交
723 724
 * 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
725 726
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
727 728 729
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
730 731 732 733 734 735
 * 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
736 737
 *
 *
N
Nick Piggin 已提交
738
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
739 740 741 742 743 744 745 746 747
 *
 * 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
748
 */
N
Nick Piggin 已提交
749 750 751 752 753 754 755
#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
756
{
757
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
758 759

	if (HAVE_PTE_SPECIAL) {
760
		if (likely(!pte_special(pte)))
761
			goto check_pfn;
762 763
		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
764 765
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
766
		if (!is_zero_pfn(pfn))
767
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
768 769 770 771 772
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
773 774 775 776 777 778
	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
779 780
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
781 782 783 784 785
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
786 787
	}

788 789
	if (is_zero_pfn(pfn))
		return NULL;
790 791 792 793 794
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
795 796

	/*
N
Nick Piggin 已提交
797 798
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
799
	 */
J
Jared Hulbert 已提交
800
out:
801
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
802 803
}

804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843
#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
844 845 846 847 848 849
/*
 * 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
850
static inline unsigned long
L
Linus Torvalds 已提交
851
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
852
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
853
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
854
{
N
Nick Piggin 已提交
855
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
856 857 858 859 860
	pte_t pte = *src_pte;
	struct page *page;

	/* pte contains position in swap or file, so copy. */
	if (unlikely(!pte_present(pte))) {
861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878
		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);

879
			rss[mm_counter(page)]++;
880 881 882 883 884 885 886 887 888 889 890 891

			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);
892
			}
L
Linus Torvalds 已提交
893
		}
894
		goto out_set_pte;
L
Linus Torvalds 已提交
895 896 897 898 899 900
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
901
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
902
		ptep_set_wrprotect(src_mm, addr, src_pte);
903
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
904 905 906 907 908 909 910 911 912
	}

	/*
	 * 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);
913 914 915 916

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
917
		page_dup_rmap(page, false);
918
		rss[mm_counter(page)]++;
919
	}
920 921 922

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
923
	return 0;
L
Linus Torvalds 已提交
924 925
}

926
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
927 928
		   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
929
{
930
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
931
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
932
	spinlock_t *src_ptl, *dst_ptl;
933
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
934
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
935
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
936 937

again:
K
KAMEZAWA Hiroyuki 已提交
938 939
	init_rss_vec(rss);

H
Hugh Dickins 已提交
940
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
941 942
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
943
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
944
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
945
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
946 947
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
948
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
949 950 951 952 953 954

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
955 956 957
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
958
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
959 960
				break;
		}
L
Linus Torvalds 已提交
961 962 963 964
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
965 966 967 968
		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
969 970 971
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

972
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
973
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
974
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
975
	add_mm_rss_vec(dst_mm, rss);
976
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
977
	cond_resched();
H
Hugh Dickins 已提交
978 979 980 981 982 983

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001
	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);
1002
		if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
1003
			int err;
1004
			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
1005 1006 1007 1008 1009 1010 1011 1012
			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
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 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050
		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;
1051 1052 1053
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	bool is_cow;
A
Andrea Arcangeli 已提交
1054
	int ret;
L
Linus Torvalds 已提交
1055

1056 1057 1058 1059 1060 1061
	/*
	 * 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.
	 */
1062 1063 1064
	if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
			!vma->anon_vma)
		return 0;
1065

L
Linus Torvalds 已提交
1066 1067 1068
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

1069
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1070 1071 1072 1073
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
1074
		ret = track_pfn_copy(vma);
1075 1076 1077 1078
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
1079 1080 1081 1082 1083 1084
	/*
	 * 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.
	 */
1085 1086 1087 1088 1089 1090
	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
1091 1092

	ret = 0;
L
Linus Torvalds 已提交
1093 1094 1095 1096 1097 1098
	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
1099 1100 1101 1102 1103
		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
1104
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1105

1106 1107
	if (is_cow)
		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
A
Andrea Arcangeli 已提交
1108
	return ret;
L
Linus Torvalds 已提交
1109 1110
}

1111
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1112
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
1113
				unsigned long addr, unsigned long end,
1114
				struct zap_details *details)
L
Linus Torvalds 已提交
1115
{
N
Nick Piggin 已提交
1116
	struct mm_struct *mm = tlb->mm;
P
Peter Zijlstra 已提交
1117
	int force_flush = 0;
K
KAMEZAWA Hiroyuki 已提交
1118
	int rss[NR_MM_COUNTERS];
1119
	spinlock_t *ptl;
1120
	pte_t *start_pte;
1121
	pte_t *pte;
1122
	swp_entry_t entry;
K
KAMEZAWA Hiroyuki 已提交
1123

1124
	tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
P
Peter Zijlstra 已提交
1125
again:
1126
	init_rss_vec(rss);
1127 1128
	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	pte = start_pte;
1129
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1130 1131
	do {
		pte_t ptent = *pte;
1132
		if (pte_none(ptent)) {
L
Linus Torvalds 已提交
1133
			continue;
1134
		}
1135

L
Linus Torvalds 已提交
1136
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
1137
			struct page *page;
1138

1139
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
1140 1141 1142 1143 1144 1145 1146
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
1147
				    details->check_mapping != page_rmapping(page))
L
Linus Torvalds 已提交
1148 1149
					continue;
			}
N
Nick Piggin 已提交
1150
			ptent = ptep_get_and_clear_full(mm, addr, pte,
1151
							tlb->fullmm);
L
Linus Torvalds 已提交
1152 1153 1154
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
1155 1156

			if (!PageAnon(page)) {
1157
				if (pte_dirty(ptent)) {
M
Michal Hocko 已提交
1158 1159 1160 1161 1162 1163
					/*
					 * oom_reaper cannot tear down dirty
					 * pages
					 */
					if (unlikely(details && details->ignore_dirty))
						continue;
1164
					force_flush = 1;
1165
					set_page_dirty(page);
1166
				}
1167
				if (pte_young(ptent) &&
1168
				    likely(!(vma->vm_flags & VM_SEQ_READ)))
1169
					mark_page_accessed(page);
1170
			}
1171
			rss[mm_counter(page)]--;
1172
			page_remove_rmap(page, false);
1173 1174
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
1175
			if (unlikely(__tlb_remove_page(tlb, page))) {
1176
				force_flush = 1;
1177
				addr += PAGE_SIZE;
P
Peter Zijlstra 已提交
1178
				break;
1179
			}
L
Linus Torvalds 已提交
1180 1181
			continue;
		}
M
Michal Hocko 已提交
1182 1183
		/* only check swap_entries if explicitly asked for in details */
		if (unlikely(details && !details->check_swap_entries))
L
Linus Torvalds 已提交
1184
			continue;
K
KAMEZAWA Hiroyuki 已提交
1185

1186 1187 1188 1189 1190
		entry = pte_to_swp_entry(ptent);
		if (!non_swap_entry(entry))
			rss[MM_SWAPENTS]--;
		else if (is_migration_entry(entry)) {
			struct page *page;
1191

1192
			page = migration_entry_to_page(entry);
1193
			rss[mm_counter(page)]--;
K
KAMEZAWA Hiroyuki 已提交
1194
		}
1195 1196
		if (unlikely(!free_swap_and_cache(entry)))
			print_bad_pte(vma, addr, ptent, NULL);
1197
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1198
	} while (pte++, addr += PAGE_SIZE, addr != end);
1199

K
KAMEZAWA Hiroyuki 已提交
1200
	add_mm_rss_vec(mm, rss);
1201
	arch_leave_lazy_mmu_mode();
1202

1203
	/* Do the actual TLB flush before dropping ptl */
1204
	if (force_flush)
1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216
		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);
1217
		if (addr != end)
P
Peter Zijlstra 已提交
1218 1219 1220
			goto again;
	}

1221
	return addr;
L
Linus Torvalds 已提交
1222 1223
}

1224
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1225
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
1226
				unsigned long addr, unsigned long end,
1227
				struct zap_details *details)
L
Linus Torvalds 已提交
1228 1229 1230 1231 1232 1233 1234
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1235
		if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1236
			if (next - addr != HPAGE_PMD_SIZE) {
1237 1238
				VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
				    !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1239
				__split_huge_pmd(vma, pmd, addr, false, NULL);
S
Shaohua Li 已提交
1240
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1241
				goto next;
1242 1243
			/* fall through */
		}
1244 1245 1246 1247 1248 1249 1250 1251 1252
		/*
		 * 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;
1253
		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1254
next:
1255 1256
		cond_resched();
	} while (pmd++, addr = next, addr != end);
1257 1258

	return addr;
L
Linus Torvalds 已提交
1259 1260
}

1261
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1262
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1263
				unsigned long addr, unsigned long end,
1264
				struct zap_details *details)
L
Linus Torvalds 已提交
1265 1266 1267 1268 1269 1270 1271
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1272
		if (pud_none_or_clear_bad(pud))
L
Linus Torvalds 已提交
1273
			continue;
1274 1275
		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
	} while (pud++, addr = next, addr != end);
1276 1277

	return addr;
L
Linus Torvalds 已提交
1278 1279
}

M
Michal Hocko 已提交
1280
void unmap_page_range(struct mmu_gather *tlb,
A
Al Viro 已提交
1281 1282 1283
			     struct vm_area_struct *vma,
			     unsigned long addr, unsigned long end,
			     struct zap_details *details)
L
Linus Torvalds 已提交
1284 1285 1286 1287 1288 1289 1290 1291 1292
{
	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);
1293
		if (pgd_none_or_clear_bad(pgd))
L
Linus Torvalds 已提交
1294
			continue;
1295 1296
		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
	} while (pgd++, addr = next, addr != end);
L
Linus Torvalds 已提交
1297 1298
	tlb_end_vma(tlb, vma);
}
1299

1300 1301 1302

static void unmap_single_vma(struct mmu_gather *tlb,
		struct vm_area_struct *vma, unsigned long start_addr,
1303
		unsigned long end_addr,
1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314
		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;

1315 1316 1317
	if (vma->vm_file)
		uprobe_munmap(vma, start, end);

1318
	if (unlikely(vma->vm_flags & VM_PFNMAP))
1319
		untrack_pfn(vma, 0, 0);
1320 1321 1322 1323 1324 1325 1326

	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
1327
			 * cleanup path of mmap_region. When
1328
			 * hugetlbfs ->mmap method fails,
1329
			 * mmap_region() nullifies vma->vm_file
1330 1331 1332 1333
			 * before calling this function to clean up.
			 * Since no pte has actually been setup, it is
			 * safe to do nothing in this case.
			 */
1334
			if (vma->vm_file) {
1335
				i_mmap_lock_write(vma->vm_file->f_mapping);
1336
				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1337
				i_mmap_unlock_write(vma->vm_file->f_mapping);
1338
			}
1339 1340 1341
		} else
			unmap_page_range(tlb, vma, start, end, details);
	}
L
Linus Torvalds 已提交
1342 1343 1344 1345
}

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
1346
 * @tlb: address of the caller's struct mmu_gather
L
Linus Torvalds 已提交
1347 1348 1349 1350
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 *
1351
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1352 1353 1354 1355 1356 1357 1358 1359 1360 1361
 *
 * 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
1362
void unmap_vmas(struct mmu_gather *tlb,
L
Linus Torvalds 已提交
1363
		struct vm_area_struct *vma, unsigned long start_addr,
1364
		unsigned long end_addr)
L
Linus Torvalds 已提交
1365
{
A
Andrea Arcangeli 已提交
1366
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1367

A
Andrea Arcangeli 已提交
1368
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1369
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1370
		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
A
Andrea Arcangeli 已提交
1371
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1372 1373 1374 1375 1376
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
1377
 * @start: starting address of pages to zap
L
Linus Torvalds 已提交
1378
 * @size: number of bytes to zap
1379
 * @details: details of shared cache invalidation
1380 1381
 *
 * Caller must protect the VMA list
L
Linus Torvalds 已提交
1382
 */
1383
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
L
Linus Torvalds 已提交
1384 1385 1386
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1387
	struct mmu_gather tlb;
1388
	unsigned long end = start + size;
L
Linus Torvalds 已提交
1389 1390

	lru_add_drain();
1391
	tlb_gather_mmu(&tlb, mm, start, end);
1392
	update_hiwater_rss(mm);
1393 1394
	mmu_notifier_invalidate_range_start(mm, start, end);
	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1395
		unmap_single_vma(&tlb, vma, start, end, details);
1396 1397
	mmu_notifier_invalidate_range_end(mm, start, end);
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
1398 1399
}

1400 1401 1402 1403 1404
/**
 * 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
1405
 * @details: details of shared cache invalidation
1406 1407
 *
 * The range must fit into one VMA.
L
Linus Torvalds 已提交
1408
 */
1409
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1410 1411 1412
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1413
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1414 1415 1416
	unsigned long end = address + size;

	lru_add_drain();
1417
	tlb_gather_mmu(&tlb, mm, address, end);
1418
	update_hiwater_rss(mm);
1419
	mmu_notifier_invalidate_range_start(mm, address, end);
1420
	unmap_single_vma(&tlb, vma, address, end, details);
1421
	mmu_notifier_invalidate_range_end(mm, address, end);
P
Peter Zijlstra 已提交
1422
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1423 1424
}

1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442
/**
 * 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;
1443
	zap_page_range_single(vma, address, size, NULL);
1444 1445 1446 1447
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

1448
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
1449
			spinlock_t **ptl)
1450 1451 1452 1453
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1454
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1455 1456
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
1457
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1458
		}
1459 1460 1461 1462
	}
	return NULL;
}

1463 1464 1465 1466 1467 1468 1469
/*
 * 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
1470 1471
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1472
{
N
Nick Piggin 已提交
1473
	struct mm_struct *mm = vma->vm_mm;
1474
	int retval;
1475
	pte_t *pte;
1476 1477
	spinlock_t *ptl;

1478
	retval = -EINVAL;
1479
	if (PageAnon(page))
1480
		goto out;
1481 1482
	retval = -ENOMEM;
	flush_dcache_page(page);
1483
	pte = get_locked_pte(mm, addr, &ptl);
1484
	if (!pte)
1485
		goto out;
1486 1487 1488 1489 1490 1491
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
1492
	inc_mm_counter_fast(mm, mm_counter_file(page));
K
Kirill A. Shutemov 已提交
1493
	page_add_file_rmap(page, false);
1494 1495 1496
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1497 1498
	pte_unmap_unlock(pte, ptl);
	return retval;
1499 1500 1501 1502 1503 1504
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1505 1506 1507 1508 1509 1510
/**
 * 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
 *
1511 1512 1513 1514 1515 1516
 * 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
1517
 * (see split_page()).
1518 1519 1520 1521 1522 1523 1524 1525
 *
 * 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.
1526 1527 1528 1529 1530
 *
 * 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.
1531
 */
N
Nick Piggin 已提交
1532 1533
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1534 1535 1536 1537 1538
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1539 1540 1541 1542 1543
	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
1544
	return insert_page(vma, addr, page, vma->vm_page_prot);
1545
}
1546
EXPORT_SYMBOL(vm_insert_page);
1547

N
Nick Piggin 已提交
1548
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1549
			pfn_t pfn, pgprot_t prot)
N
Nick Piggin 已提交
1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564
{
	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.. */
1565 1566 1567 1568
	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
1569
	set_pte_at(mm, addr, pte, entry);
1570
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1571 1572 1573 1574 1575 1576 1577 1578

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

N
Nick Piggin 已提交
1579 1580 1581 1582 1583 1584
/**
 * 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
 *
1585
 * Similar to vm_insert_page, this allows drivers to insert individual pages
N
Nick Piggin 已提交
1586 1587 1588 1589
 * 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
1590 1591 1592 1593 1594
 *
 * 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
1595 1596
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1597
			unsigned long pfn)
A
Andy Lutomirski 已提交
1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619
{
	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
1620
{
1621
	int ret;
N
Nick Piggin 已提交
1622 1623 1624 1625 1626 1627
	/*
	 * 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
1628 1629 1630 1631 1632
	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
1633

N
Nick Piggin 已提交
1634 1635
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1636 1637

	track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1638

1639
	ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
1640 1641

	return ret;
N
Nick Piggin 已提交
1642
}
A
Andy Lutomirski 已提交
1643
EXPORT_SYMBOL(vm_insert_pfn_prot);
N
Nick Piggin 已提交
1644

N
Nick Piggin 已提交
1645
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1646
			pfn_t pfn)
N
Nick Piggin 已提交
1647
{
1648 1649
	pgprot_t pgprot = vma->vm_page_prot;

N
Nick Piggin 已提交
1650
	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
N
Nick Piggin 已提交
1651

N
Nick Piggin 已提交
1652 1653
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1654 1655

	track_pfn_insert(vma, &pgprot, pfn);
N
Nick Piggin 已提交
1656

N
Nick Piggin 已提交
1657 1658 1659 1660
	/*
	 * 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
1661 1662
	 * 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
1663
	 */
1664
	if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
N
Nick Piggin 已提交
1665 1666
		struct page *page;

1667 1668 1669 1670 1671 1672
		/*
		 * 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));
1673
		return insert_page(vma, addr, page, pgprot);
N
Nick Piggin 已提交
1674
	}
1675
	return insert_pfn(vma, addr, pfn, pgprot);
N
Nick Piggin 已提交
1676
}
N
Nick Piggin 已提交
1677
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1678

L
Linus Torvalds 已提交
1679 1680 1681 1682 1683 1684 1685 1686 1687 1688
/*
 * 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
1689
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1690

H
Hugh Dickins 已提交
1691
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1692 1693
	if (!pte)
		return -ENOMEM;
1694
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1695 1696
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1697
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1698 1699
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1700
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1701
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715
	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;
1716
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745
	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;
}

1746 1747 1748 1749 1750 1751 1752 1753 1754 1755
/**
 * 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
1756 1757 1758 1759 1760
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;
1761
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1762
	struct mm_struct *mm = vma->vm_mm;
1763
	unsigned long remap_pfn = pfn;
L
Linus Torvalds 已提交
1764 1765 1766 1767 1768 1769 1770
	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).
1771 1772 1773
	 *   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.
1774 1775 1776 1777
	 *   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
1778 1779 1780 1781
	 *
	 * 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".
1782
	 * See vm_normal_page() for details.
L
Linus Torvalds 已提交
1783
	 */
1784 1785 1786
	if (is_cow_mapping(vma->vm_flags)) {
		if (addr != vma->vm_start || end != vma->vm_end)
			return -EINVAL;
L
Linus Torvalds 已提交
1787
		vma->vm_pgoff = pfn;
1788 1789
	}

1790
	err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
1791
	if (err)
1792
		return -EINVAL;
L
Linus Torvalds 已提交
1793

1794
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
L
Linus Torvalds 已提交
1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806

	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);
1807 1808

	if (err)
1809
		untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
1810

L
Linus Torvalds 已提交
1811 1812 1813 1814
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

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 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861
/**
 * 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);

1862 1863 1864 1865 1866 1867
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;
1868
	pgtable_t token;
1869
	spinlock_t *uninitialized_var(ptl);
1870 1871 1872 1873 1874 1875 1876 1877 1878

	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));

1879 1880
	arch_enter_lazy_mmu_mode();

1881
	token = pmd_pgtable(*pmd);
1882 1883

	do {
1884
		err = fn(pte++, token, addr, data);
1885 1886
		if (err)
			break;
1887
	} while (addr += PAGE_SIZE, addr != end);
1888

1889 1890
	arch_leave_lazy_mmu_mode();

1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903
	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
1904 1905
	BUG_ON(pud_huge(*pud));

1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946
	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;
1947
	unsigned long end = addr + size;
1948 1949
	int err;

1950 1951 1952
	if (WARN_ON(addr >= end))
		return -EINVAL;

1953 1954 1955 1956 1957 1958 1959
	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);
1960

1961 1962 1963 1964
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1965
/*
1966 1967 1968 1969 1970
 * 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;
1971
 * and do_anonymous_page can safely check later on).
1972
 */
H
Hugh Dickins 已提交
1973
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1974 1975 1976 1977 1978
				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
1979 1980
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1981
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1982
		spin_unlock(ptl);
1983 1984 1985 1986 1987 1988
	}
#endif
	pte_unmap(page_table);
	return same;
}

1989
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1990
{
1991 1992
	debug_dma_assert_idle(src);

1993 1994 1995 1996 1997 1998 1999
	/*
	 * 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)) {
2000
		void *kaddr = kmap_atomic(dst);
L
Linus Torvalds 已提交
2001 2002 2003 2004 2005 2006 2007 2008 2009
		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))
2010
			clear_page(kaddr);
2011
		kunmap_atomic(kaddr);
2012
		flush_dcache_page(dst);
N
Nick Piggin 已提交
2013 2014
	} else
		copy_user_highpage(dst, src, va, vma);
2015 2016
}

2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030
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;
}

2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042
/*
 * 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;

2043
	vmf.address = address & PAGE_MASK;
2044 2045
	vmf.pgoff = page->index;
	vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2046
	vmf.gfp_mask = __get_fault_gfp_mask(vma);
2047
	vmf.page = page;
2048
	vmf.cow_page = NULL;
2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064

	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;
}

2065 2066 2067 2068 2069 2070 2071 2072
/*
 * 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.
 */
J
Jan Kara 已提交
2073 2074
static inline int wp_page_reuse(struct vm_fault *vmf, struct page *page,
				int page_mkwrite, int dirty_shared)
J
Jan Kara 已提交
2075
	__releases(vmf->ptl)
2076
{
J
Jan Kara 已提交
2077
	struct vm_area_struct *vma = vmf->vma;
2078 2079 2080 2081 2082 2083 2084 2085 2086
	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);

J
Jan Kara 已提交
2087 2088
	flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
	entry = pte_mkyoung(vmf->orig_pte);
2089
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
J
Jan Kara 已提交
2090 2091 2092
	if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
		update_mmu_cache(vma, vmf->address, vmf->pte);
	pte_unmap_unlock(vmf->pte, vmf->ptl);
2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104

	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);
2105
		put_page(page);
2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121

		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;
}

2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137
/*
 * 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.
 */
J
Jan Kara 已提交
2138
static int wp_page_copy(struct vm_fault *vmf, struct page *old_page)
2139
{
J
Jan Kara 已提交
2140
	struct vm_area_struct *vma = vmf->vma;
K
Kirill A. Shutemov 已提交
2141
	struct mm_struct *mm = vma->vm_mm;
2142 2143 2144
	struct page *new_page = NULL;
	pte_t entry;
	int page_copied = 0;
J
Jan Kara 已提交
2145
	const unsigned long mmun_start = vmf->address & PAGE_MASK;
K
Kirill A. Shutemov 已提交
2146
	const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2147 2148 2149 2150 2151
	struct mem_cgroup *memcg;

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

J
Jan Kara 已提交
2152
	if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
J
Jan Kara 已提交
2153 2154
		new_page = alloc_zeroed_user_highpage_movable(vma,
							      vmf->address);
2155 2156 2157
		if (!new_page)
			goto oom;
	} else {
K
Kirill A. Shutemov 已提交
2158
		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
J
Jan Kara 已提交
2159
				vmf->address);
2160 2161
		if (!new_page)
			goto oom;
J
Jan Kara 已提交
2162
		cow_user_page(new_page, old_page, vmf->address, vma);
2163 2164
	}

2165
	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2166 2167
		goto oom_free_new;

2168 2169
	__SetPageUptodate(new_page);

2170 2171 2172 2173 2174
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);

	/*
	 * Re-check the pte - we dropped the lock
	 */
J
Jan Kara 已提交
2175
	vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
J
Jan Kara 已提交
2176
	if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2177 2178
		if (old_page) {
			if (!PageAnon(old_page)) {
2179 2180
				dec_mm_counter_fast(mm,
						mm_counter_file(old_page));
2181 2182 2183 2184 2185
				inc_mm_counter_fast(mm, MM_ANONPAGES);
			}
		} else {
			inc_mm_counter_fast(mm, MM_ANONPAGES);
		}
J
Jan Kara 已提交
2186
		flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2187 2188 2189 2190 2191 2192 2193 2194
		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.
		 */
J
Jan Kara 已提交
2195 2196
		ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
		page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2197
		mem_cgroup_commit_charge(new_page, memcg, false, false);
2198 2199 2200 2201 2202 2203
		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.
		 */
J
Jan Kara 已提交
2204 2205
		set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
		update_mmu_cache(vma, vmf->address, vmf->pte);
2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228
		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.
			 */
2229
			page_remove_rmap(old_page, false);
2230 2231 2232 2233 2234 2235
		}

		/* Free the old page.. */
		new_page = old_page;
		page_copied = 1;
	} else {
2236
		mem_cgroup_cancel_charge(new_page, memcg, false);
2237 2238 2239
	}

	if (new_page)
2240
		put_page(new_page);
2241

J
Jan Kara 已提交
2242
	pte_unmap_unlock(vmf->pte, vmf->ptl);
2243 2244 2245 2246 2247 2248 2249 2250
	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 */
2251 2252
			if (PageMlocked(old_page))
				munlock_vma_page(old_page);
2253 2254
			unlock_page(old_page);
		}
2255
		put_page(old_page);
2256 2257 2258
	}
	return page_copied ? VM_FAULT_WRITE : 0;
oom_free_new:
2259
	put_page(new_page);
2260 2261
oom:
	if (old_page)
2262
		put_page(old_page);
2263 2264 2265
	return VM_FAULT_OOM;
}

2266 2267 2268 2269
/*
 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
 * mapping
 */
J
Jan Kara 已提交
2270
static int wp_pfn_shared(struct vm_fault *vmf)
2271
{
J
Jan Kara 已提交
2272
	struct vm_area_struct *vma = vmf->vma;
K
Kirill A. Shutemov 已提交
2273

2274 2275 2276
	if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
		int ret;

J
Jan Kara 已提交
2277
		pte_unmap_unlock(vmf->pte, vmf->ptl);
2278 2279
		vmf->flags |= FAULT_FLAG_MKWRITE;
		ret = vma->vm_ops->pfn_mkwrite(vma, vmf);
2280 2281
		if (ret & VM_FAULT_ERROR)
			return ret;
J
Jan Kara 已提交
2282 2283
		vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
				vmf->address, &vmf->ptl);
2284 2285 2286 2287
		/*
		 * We might have raced with another page fault while we
		 * released the pte_offset_map_lock.
		 */
J
Jan Kara 已提交
2288
		if (!pte_same(*vmf->pte, vmf->orig_pte)) {
J
Jan Kara 已提交
2289
			pte_unmap_unlock(vmf->pte, vmf->ptl);
2290 2291 2292
			return 0;
		}
	}
J
Jan Kara 已提交
2293
	return wp_page_reuse(vmf, NULL, 0, 0);
2294 2295
}

J
Jan Kara 已提交
2296
static int wp_page_shared(struct vm_fault *vmf, struct page *old_page)
J
Jan Kara 已提交
2297
	__releases(vmf->ptl)
2298
{
J
Jan Kara 已提交
2299
	struct vm_area_struct *vma = vmf->vma;
2300 2301
	int page_mkwrite = 0;

2302
	get_page(old_page);
2303 2304 2305 2306

	if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
		int tmp;

J
Jan Kara 已提交
2307 2308
		pte_unmap_unlock(vmf->pte, vmf->ptl);
		tmp = do_page_mkwrite(vma, old_page, vmf->address);
2309 2310
		if (unlikely(!tmp || (tmp &
				      (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2311
			put_page(old_page);
2312 2313 2314 2315 2316 2317 2318 2319
			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.
		 */
J
Jan Kara 已提交
2320 2321
		vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
						vmf->address, &vmf->ptl);
J
Jan Kara 已提交
2322
		if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2323
			unlock_page(old_page);
J
Jan Kara 已提交
2324
			pte_unmap_unlock(vmf->pte, vmf->ptl);
2325
			put_page(old_page);
2326 2327 2328 2329 2330
			return 0;
		}
		page_mkwrite = 1;
	}

J
Jan Kara 已提交
2331
	return wp_page_reuse(vmf, old_page, page_mkwrite, 1);
2332 2333
}

L
Linus Torvalds 已提交
2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347
/*
 * 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.
 *
2348 2349 2350
 * 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
2351
 */
J
Jan Kara 已提交
2352
static int do_wp_page(struct vm_fault *vmf)
J
Jan Kara 已提交
2353
	__releases(vmf->ptl)
L
Linus Torvalds 已提交
2354
{
J
Jan Kara 已提交
2355
	struct vm_area_struct *vma = vmf->vma;
2356
	struct page *old_page;
L
Linus Torvalds 已提交
2357

J
Jan Kara 已提交
2358
	old_page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2359 2360
	if (!old_page) {
		/*
2361 2362
		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
		 * VM_PFNMAP VMA.
2363 2364
		 *
		 * We should not cow pages in a shared writeable mapping.
2365
		 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2366 2367 2368
		 */
		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
				     (VM_WRITE|VM_SHARED))
J
Jan Kara 已提交
2369
			return wp_pfn_shared(vmf);
2370

J
Jan Kara 已提交
2371
		pte_unmap_unlock(vmf->pte, vmf->ptl);
J
Jan Kara 已提交
2372
		return wp_page_copy(vmf, old_page);
2373
	}
L
Linus Torvalds 已提交
2374

2375
	/*
P
Peter Zijlstra 已提交
2376 2377
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2378
	 */
H
Hugh Dickins 已提交
2379
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2380
		int total_mapcount;
2381
		if (!trylock_page(old_page)) {
2382
			get_page(old_page);
J
Jan Kara 已提交
2383
			pte_unmap_unlock(vmf->pte, vmf->ptl);
2384
			lock_page(old_page);
J
Jan Kara 已提交
2385 2386
			vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
					vmf->address, &vmf->ptl);
J
Jan Kara 已提交
2387
			if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2388
				unlock_page(old_page);
J
Jan Kara 已提交
2389
				pte_unmap_unlock(vmf->pte, vmf->ptl);
2390
				put_page(old_page);
2391
				return 0;
2392
			}
2393
			put_page(old_page);
P
Peter Zijlstra 已提交
2394
		}
2395 2396 2397 2398 2399 2400 2401 2402 2403
		if (reuse_swap_page(old_page, &total_mapcount)) {
			if (total_mapcount == 1) {
				/*
				 * 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.
				 */
2404
				page_move_anon_rmap(old_page, vma);
2405
			}
2406
			unlock_page(old_page);
J
Jan Kara 已提交
2407
			return wp_page_reuse(vmf, old_page, 0, 0);
2408
		}
2409
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2410
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2411
					(VM_WRITE|VM_SHARED))) {
J
Jan Kara 已提交
2412
		return wp_page_shared(vmf, old_page);
L
Linus Torvalds 已提交
2413 2414 2415 2416 2417
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
2418
	get_page(old_page);
2419

J
Jan Kara 已提交
2420
	pte_unmap_unlock(vmf->pte, vmf->ptl);
J
Jan Kara 已提交
2421
	return wp_page_copy(vmf, old_page);
L
Linus Torvalds 已提交
2422 2423
}

2424
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2425 2426 2427
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
2428
	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
L
Linus Torvalds 已提交
2429 2430
}

2431
static inline void unmap_mapping_range_tree(struct rb_root *root,
L
Linus Torvalds 已提交
2432 2433 2434 2435 2436
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	pgoff_t vba, vea, zba, zea;

2437
	vma_interval_tree_foreach(vma, root,
L
Linus Torvalds 已提交
2438 2439 2440
			details->first_index, details->last_index) {

		vba = vma->vm_pgoff;
2441
		vea = vba + vma_pages(vma) - 1;
L
Linus Torvalds 已提交
2442 2443 2444 2445 2446 2447 2448
		zba = details->first_index;
		if (zba < vba)
			zba = vba;
		zea = details->last_index;
		if (zea > vea)
			zea = vea;

2449
		unmap_mapping_range_vma(vma,
L
Linus Torvalds 已提交
2450 2451
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2452
				details);
L
Linus Torvalds 已提交
2453 2454 2455 2456
	}
}

/**
2457 2458 2459 2460
 * 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
2461
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2462 2463
 * @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
2464
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475
 * 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
2476
	struct zap_details details = { };
L
Linus Torvalds 已提交
2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493
	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;

2494
	i_mmap_lock_write(mapping);
2495
	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
L
Linus Torvalds 已提交
2496
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
2497
	i_mmap_unlock_write(mapping);
L
Linus Torvalds 已提交
2498 2499 2500 2501
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
2502 2503
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
2504 2505 2506 2507
 * 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
2508
 */
J
Jan Kara 已提交
2509
int do_swap_page(struct vm_fault *vmf)
L
Linus Torvalds 已提交
2510
{
J
Jan Kara 已提交
2511
	struct vm_area_struct *vma = vmf->vma;
2512
	struct page *page, *swapcache;
2513
	struct mem_cgroup *memcg;
2514
	swp_entry_t entry;
L
Linus Torvalds 已提交
2515
	pte_t pte;
2516
	int locked;
2517
	int exclusive = 0;
N
Nick Piggin 已提交
2518
	int ret = 0;
L
Linus Torvalds 已提交
2519

J
Jan Kara 已提交
2520
	if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2521
		goto out;
2522

J
Jan Kara 已提交
2523
	entry = pte_to_swp_entry(vmf->orig_pte);
2524 2525
	if (unlikely(non_swap_entry(entry))) {
		if (is_migration_entry(entry)) {
J
Jan Kara 已提交
2526 2527
			migration_entry_wait(vma->vm_mm, vmf->pmd,
					     vmf->address);
2528 2529 2530
		} else if (is_hwpoison_entry(entry)) {
			ret = VM_FAULT_HWPOISON;
		} else {
J
Jan Kara 已提交
2531
			print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
H
Hugh Dickins 已提交
2532
			ret = VM_FAULT_SIGBUS;
2533
		}
2534 2535
		goto out;
	}
2536
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2537 2538
	page = lookup_swap_cache(entry);
	if (!page) {
J
Jan Kara 已提交
2539 2540
		page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, vma,
					vmf->address);
L
Linus Torvalds 已提交
2541 2542
		if (!page) {
			/*
2543 2544
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2545
			 */
J
Jan Kara 已提交
2546 2547
			vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
					vmf->address, &vmf->ptl);
J
Jan Kara 已提交
2548
			if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
L
Linus Torvalds 已提交
2549
				ret = VM_FAULT_OOM;
2550
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2551
			goto unlock;
L
Linus Torvalds 已提交
2552 2553 2554 2555
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2556
		count_vm_event(PGMAJFAULT);
K
Kirill A. Shutemov 已提交
2557
		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
2558
	} else if (PageHWPoison(page)) {
2559 2560 2561 2562
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2563 2564
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2565
		swapcache = page;
2566
		goto out_release;
L
Linus Torvalds 已提交
2567 2568
	}

2569
	swapcache = page;
J
Jan Kara 已提交
2570
	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
R
Rik van Riel 已提交
2571

2572
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2573 2574 2575 2576
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2577

A
Andrea Arcangeli 已提交
2578
	/*
2579 2580 2581 2582
	 * 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
2583
	 */
2584
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2585 2586
		goto out_page;

J
Jan Kara 已提交
2587
	page = ksm_might_need_to_copy(page, vma, vmf->address);
2588 2589 2590 2591
	if (unlikely(!page)) {
		ret = VM_FAULT_OOM;
		page = swapcache;
		goto out_page;
H
Hugh Dickins 已提交
2592 2593
	}

K
Kirill A. Shutemov 已提交
2594 2595
	if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
				&memcg, false)) {
2596
		ret = VM_FAULT_OOM;
2597
		goto out_page;
2598 2599
	}

L
Linus Torvalds 已提交
2600
	/*
2601
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2602
	 */
J
Jan Kara 已提交
2603 2604
	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
			&vmf->ptl);
J
Jan Kara 已提交
2605
	if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2606 2607 2608 2609 2610
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2611 2612
	}

2613 2614 2615 2616 2617 2618 2619 2620 2621
	/*
	 * 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
2622

K
Kirill A. Shutemov 已提交
2623 2624
	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
	dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
2625
	pte = mk_pte(page, vma->vm_page_prot);
J
Jan Kara 已提交
2626
	if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
L
Linus Torvalds 已提交
2627
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
J
Jan Kara 已提交
2628
		vmf->flags &= ~FAULT_FLAG_WRITE;
2629
		ret |= VM_FAULT_WRITE;
2630
		exclusive = RMAP_EXCLUSIVE;
L
Linus Torvalds 已提交
2631 2632
	}
	flush_icache_page(vma, page);
J
Jan Kara 已提交
2633
	if (pte_swp_soft_dirty(vmf->orig_pte))
2634
		pte = pte_mksoft_dirty(pte);
J
Jan Kara 已提交
2635
	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
J
Jan Kara 已提交
2636
	vmf->orig_pte = pte;
2637
	if (page == swapcache) {
J
Jan Kara 已提交
2638
		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
2639
		mem_cgroup_commit_charge(page, memcg, true, false);
2640
		activate_page(page);
2641
	} else { /* ksm created a completely new copy */
J
Jan Kara 已提交
2642
		page_add_new_anon_rmap(page, vma, vmf->address, false);
2643
		mem_cgroup_commit_charge(page, memcg, false, false);
2644 2645
		lru_cache_add_active_or_unevictable(page, vma);
	}
L
Linus Torvalds 已提交
2646

2647
	swap_free(entry);
2648 2649
	if (mem_cgroup_swap_full(page) ||
	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2650
		try_to_free_swap(page);
2651
	unlock_page(page);
2652
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2653 2654 2655 2656 2657 2658 2659 2660 2661
		/*
		 * 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);
2662
		put_page(swapcache);
A
Andrea Arcangeli 已提交
2663
	}
2664

J
Jan Kara 已提交
2665
	if (vmf->flags & FAULT_FLAG_WRITE) {
J
Jan Kara 已提交
2666
		ret |= do_wp_page(vmf);
2667 2668
		if (ret & VM_FAULT_ERROR)
			ret &= VM_FAULT_ERROR;
L
Linus Torvalds 已提交
2669 2670 2671 2672
		goto out;
	}

	/* No need to invalidate - it was non-present before */
J
Jan Kara 已提交
2673
	update_mmu_cache(vma, vmf->address, vmf->pte);
2674
unlock:
J
Jan Kara 已提交
2675
	pte_unmap_unlock(vmf->pte, vmf->ptl);
L
Linus Torvalds 已提交
2676 2677
out:
	return ret;
2678
out_nomap:
2679
	mem_cgroup_cancel_charge(page, memcg, false);
J
Jan Kara 已提交
2680
	pte_unmap_unlock(vmf->pte, vmf->ptl);
2681
out_page:
2682
	unlock_page(page);
2683
out_release:
2684
	put_page(page);
2685
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2686
		unlock_page(swapcache);
2687
		put_page(swapcache);
A
Andrea Arcangeli 已提交
2688
	}
2689
	return ret;
L
Linus Torvalds 已提交
2690 2691
}

2692
/*
2693 2694
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2695 2696 2697 2698 2699 2700
 * 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) {
2701 2702 2703 2704 2705 2706 2707 2708 2709 2710
		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;
2711

2712
		return expand_downwards(vma, address - PAGE_SIZE);
2713
	}
2714 2715 2716 2717 2718 2719 2720
	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;

2721
		return expand_upwards(vma, address + PAGE_SIZE);
2722
	}
2723 2724 2725
	return 0;
}

L
Linus Torvalds 已提交
2726
/*
2727 2728 2729
 * 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
2730
 */
J
Jan Kara 已提交
2731
static int do_anonymous_page(struct vm_fault *vmf)
L
Linus Torvalds 已提交
2732
{
J
Jan Kara 已提交
2733
	struct vm_area_struct *vma = vmf->vma;
2734
	struct mem_cgroup *memcg;
2735
	struct page *page;
L
Linus Torvalds 已提交
2736 2737
	pte_t entry;

2738 2739 2740 2741
	/* File mapping without ->vm_ops ? */
	if (vma->vm_flags & VM_SHARED)
		return VM_FAULT_SIGBUS;

2742
	/* Check if we need to add a guard page to the stack */
J
Jan Kara 已提交
2743
	if (check_stack_guard_page(vma, vmf->address) < 0)
2744
		return VM_FAULT_SIGSEGV;
2745

2746 2747 2748 2749 2750 2751 2752 2753 2754 2755
	/*
	 * Use pte_alloc() instead of pte_alloc_map().  We can't run
	 * pte_offset_map() on pmds where a huge pmd might be created
	 * from a different thread.
	 *
	 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
	 * parallel threads are excluded by other means.
	 *
	 * Here we only have down_read(mmap_sem).
	 */
J
Jan Kara 已提交
2756
	if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
2757 2758 2759
		return VM_FAULT_OOM;

	/* See the comment in pte_alloc_one_map() */
J
Jan Kara 已提交
2760
	if (unlikely(pmd_trans_unstable(vmf->pmd)))
2761 2762
		return 0;

2763
	/* Use the zero-page for reads */
J
Jan Kara 已提交
2764
	if (!(vmf->flags & FAULT_FLAG_WRITE) &&
K
Kirill A. Shutemov 已提交
2765
			!mm_forbids_zeropage(vma->vm_mm)) {
J
Jan Kara 已提交
2766
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
H
Hugh Dickins 已提交
2767
						vma->vm_page_prot));
J
Jan Kara 已提交
2768 2769 2770
		vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
				vmf->address, &vmf->ptl);
		if (!pte_none(*vmf->pte))
H
Hugh Dickins 已提交
2771
			goto unlock;
2772 2773
		/* Deliver the page fault to userland, check inside PT lock */
		if (userfaultfd_missing(vma)) {
J
Jan Kara 已提交
2774 2775
			pte_unmap_unlock(vmf->pte, vmf->ptl);
			return handle_userfault(vmf, VM_UFFD_MISSING);
2776
		}
H
Hugh Dickins 已提交
2777 2778 2779
		goto setpte;
	}

N
Nick Piggin 已提交
2780 2781 2782
	/* Allocate our own private page. */
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
J
Jan Kara 已提交
2783
	page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
N
Nick Piggin 已提交
2784 2785
	if (!page)
		goto oom;
2786

K
Kirill A. Shutemov 已提交
2787
	if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
2788 2789
		goto oom_free_page;

2790 2791 2792 2793 2794
	/*
	 * 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
2795
	__SetPageUptodate(page);
2796

N
Nick Piggin 已提交
2797
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
2798 2799
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
2800

J
Jan Kara 已提交
2801 2802 2803
	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
			&vmf->ptl);
	if (!pte_none(*vmf->pte))
N
Nick Piggin 已提交
2804
		goto release;
H
Hugh Dickins 已提交
2805

2806 2807
	/* Deliver the page fault to userland, check inside PT lock */
	if (userfaultfd_missing(vma)) {
J
Jan Kara 已提交
2808
		pte_unmap_unlock(vmf->pte, vmf->ptl);
2809
		mem_cgroup_cancel_charge(page, memcg, false);
2810
		put_page(page);
J
Jan Kara 已提交
2811
		return handle_userfault(vmf, VM_UFFD_MISSING);
2812 2813
	}

K
Kirill A. Shutemov 已提交
2814
	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
J
Jan Kara 已提交
2815
	page_add_new_anon_rmap(page, vma, vmf->address, false);
2816
	mem_cgroup_commit_charge(page, memcg, false, false);
2817
	lru_cache_add_active_or_unevictable(page, vma);
H
Hugh Dickins 已提交
2818
setpte:
J
Jan Kara 已提交
2819
	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
L
Linus Torvalds 已提交
2820 2821

	/* No need to invalidate - it was non-present before */
J
Jan Kara 已提交
2822
	update_mmu_cache(vma, vmf->address, vmf->pte);
2823
unlock:
J
Jan Kara 已提交
2824
	pte_unmap_unlock(vmf->pte, vmf->ptl);
N
Nick Piggin 已提交
2825
	return 0;
2826
release:
2827
	mem_cgroup_cancel_charge(page, memcg, false);
2828
	put_page(page);
2829
	goto unlock;
2830
oom_free_page:
2831
	put_page(page);
2832
oom:
L
Linus Torvalds 已提交
2833 2834 2835
	return VM_FAULT_OOM;
}

2836 2837 2838 2839 2840
/*
 * 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().
 */
J
Jan Kara 已提交
2841
static int __do_fault(struct vm_fault *vmf)
2842
{
J
Jan Kara 已提交
2843
	struct vm_area_struct *vma = vmf->vma;
2844 2845
	int ret;

2846
	ret = vma->vm_ops->fault(vma, vmf);
2847 2848
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
			    VM_FAULT_DAX_LOCKED | VM_FAULT_DONE_COW)))
2849
		return ret;
2850

2851
	if (unlikely(PageHWPoison(vmf->page))) {
2852
		if (ret & VM_FAULT_LOCKED)
2853 2854
			unlock_page(vmf->page);
		put_page(vmf->page);
J
Jan Kara 已提交
2855
		vmf->page = NULL;
2856 2857 2858 2859
		return VM_FAULT_HWPOISON;
	}

	if (unlikely(!(ret & VM_FAULT_LOCKED)))
2860
		lock_page(vmf->page);
2861
	else
2862
		VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
2863 2864 2865 2866

	return ret;
}

J
Jan Kara 已提交
2867
static int pte_alloc_one_map(struct vm_fault *vmf)
2868
{
J
Jan Kara 已提交
2869
	struct vm_area_struct *vma = vmf->vma;
2870

J
Jan Kara 已提交
2871
	if (!pmd_none(*vmf->pmd))
2872
		goto map_pte;
J
Jan Kara 已提交
2873 2874 2875 2876
	if (vmf->prealloc_pte) {
		vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
		if (unlikely(!pmd_none(*vmf->pmd))) {
			spin_unlock(vmf->ptl);
2877 2878 2879 2880
			goto map_pte;
		}

		atomic_long_inc(&vma->vm_mm->nr_ptes);
J
Jan Kara 已提交
2881 2882 2883 2884
		pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
		spin_unlock(vmf->ptl);
		vmf->prealloc_pte = 0;
	} else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898
		return VM_FAULT_OOM;
	}
map_pte:
	/*
	 * 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.
	 */
J
Jan Kara 已提交
2899
	if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd))
2900 2901
		return VM_FAULT_NOPAGE;

J
Jan Kara 已提交
2902 2903
	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
			&vmf->ptl);
2904 2905 2906
	return 0;
}

2907
#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
K
Kirill A. Shutemov 已提交
2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920

#define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
		unsigned long haddr)
{
	if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
			(vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
		return false;
	if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
		return false;
	return true;
}

J
Jan Kara 已提交
2921
static void deposit_prealloc_pte(struct vm_fault *vmf)
2922
{
J
Jan Kara 已提交
2923
	struct vm_area_struct *vma = vmf->vma;
2924

J
Jan Kara 已提交
2925
	pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
2926 2927 2928 2929 2930
	/*
	 * We are going to consume the prealloc table,
	 * count that as nr_ptes.
	 */
	atomic_long_inc(&vma->vm_mm->nr_ptes);
J
Jan Kara 已提交
2931
	vmf->prealloc_pte = 0;
2932 2933
}

J
Jan Kara 已提交
2934
static int do_set_pmd(struct vm_fault *vmf, struct page *page)
K
Kirill A. Shutemov 已提交
2935
{
J
Jan Kara 已提交
2936 2937 2938
	struct vm_area_struct *vma = vmf->vma;
	bool write = vmf->flags & FAULT_FLAG_WRITE;
	unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
K
Kirill A. Shutemov 已提交
2939 2940 2941 2942 2943 2944 2945 2946 2947
	pmd_t entry;
	int i, ret;

	if (!transhuge_vma_suitable(vma, haddr))
		return VM_FAULT_FALLBACK;

	ret = VM_FAULT_FALLBACK;
	page = compound_head(page);

2948 2949 2950 2951
	/*
	 * Archs like ppc64 need additonal space to store information
	 * related to pte entry. Use the preallocated table for that.
	 */
J
Jan Kara 已提交
2952 2953 2954
	if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
		vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
		if (!vmf->prealloc_pte)
2955 2956 2957 2958
			return VM_FAULT_OOM;
		smp_wmb(); /* See comment in __pte_alloc() */
	}

J
Jan Kara 已提交
2959 2960
	vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
	if (unlikely(!pmd_none(*vmf->pmd)))
K
Kirill A. Shutemov 已提交
2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971
		goto out;

	for (i = 0; i < HPAGE_PMD_NR; i++)
		flush_icache_page(vma, page + i);

	entry = mk_huge_pmd(page, vma->vm_page_prot);
	if (write)
		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);

	add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
	page_add_file_rmap(page, true);
2972 2973 2974 2975
	/*
	 * deposit and withdraw with pmd lock held
	 */
	if (arch_needs_pgtable_deposit())
J
Jan Kara 已提交
2976
		deposit_prealloc_pte(vmf);
K
Kirill A. Shutemov 已提交
2977

J
Jan Kara 已提交
2978
	set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
K
Kirill A. Shutemov 已提交
2979

J
Jan Kara 已提交
2980
	update_mmu_cache_pmd(vma, haddr, vmf->pmd);
K
Kirill A. Shutemov 已提交
2981 2982 2983

	/* fault is handled */
	ret = 0;
2984
	count_vm_event(THP_FILE_MAPPED);
K
Kirill A. Shutemov 已提交
2985
out:
2986 2987 2988 2989 2990
	/*
	 * If we are going to fallback to pte mapping, do a
	 * withdraw with pmd lock held.
	 */
	if (arch_needs_pgtable_deposit() && ret == VM_FAULT_FALLBACK)
J
Jan Kara 已提交
2991 2992 2993
		vmf->prealloc_pte = pgtable_trans_huge_withdraw(vma->vm_mm,
								vmf->pmd);
	spin_unlock(vmf->ptl);
K
Kirill A. Shutemov 已提交
2994 2995 2996
	return ret;
}
#else
J
Jan Kara 已提交
2997
static int do_set_pmd(struct vm_fault *vmf, struct page *page)
K
Kirill A. Shutemov 已提交
2998 2999 3000 3001 3002 3003
{
	BUILD_BUG();
	return 0;
}
#endif

3004
/**
3005 3006
 * alloc_set_pte - setup new PTE entry for given page and add reverse page
 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3007
 *
J
Jan Kara 已提交
3008
 * @vmf: fault environment
3009
 * @memcg: memcg to charge page (only for private mappings)
3010 3011
 * @page: page to map
 *
J
Jan Kara 已提交
3012 3013
 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
 * return.
3014 3015 3016 3017
 *
 * Target users are page handler itself and implementations of
 * vm_ops->map_pages.
 */
J
Jan Kara 已提交
3018
int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3019
		struct page *page)
3020
{
J
Jan Kara 已提交
3021 3022
	struct vm_area_struct *vma = vmf->vma;
	bool write = vmf->flags & FAULT_FLAG_WRITE;
3023
	pte_t entry;
K
Kirill A. Shutemov 已提交
3024 3025
	int ret;

J
Jan Kara 已提交
3026
	if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3027
			IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
K
Kirill A. Shutemov 已提交
3028 3029 3030
		/* THP on COW? */
		VM_BUG_ON_PAGE(memcg, page);

J
Jan Kara 已提交
3031
		ret = do_set_pmd(vmf, page);
K
Kirill A. Shutemov 已提交
3032
		if (ret != VM_FAULT_FALLBACK)
3033
			goto fault_handled;
K
Kirill A. Shutemov 已提交
3034
	}
3035

J
Jan Kara 已提交
3036 3037
	if (!vmf->pte) {
		ret = pte_alloc_one_map(vmf);
3038
		if (ret)
3039
			goto fault_handled;
3040 3041 3042
	}

	/* Re-check under ptl */
J
Jan Kara 已提交
3043
	if (unlikely(!pte_none(*vmf->pte))) {
3044 3045 3046
		ret = VM_FAULT_NOPAGE;
		goto fault_handled;
	}
3047

3048 3049 3050 3051
	flush_icache_page(vma, page);
	entry = mk_pte(page, vma->vm_page_prot);
	if (write)
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
K
Kirill A. Shutemov 已提交
3052 3053
	/* copy-on-write page */
	if (write && !(vma->vm_flags & VM_SHARED)) {
3054
		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
J
Jan Kara 已提交
3055
		page_add_new_anon_rmap(page, vma, vmf->address, false);
3056 3057
		mem_cgroup_commit_charge(page, memcg, false, false);
		lru_cache_add_active_or_unevictable(page, vma);
3058
	} else {
3059
		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
K
Kirill A. Shutemov 已提交
3060
		page_add_file_rmap(page, false);
3061
	}
J
Jan Kara 已提交
3062
	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3063 3064

	/* no need to invalidate: a not-present page won't be cached */
J
Jan Kara 已提交
3065
	update_mmu_cache(vma, vmf->address, vmf->pte);
3066
	ret = 0;
3067

3068 3069
fault_handled:
	/* preallocated pagetable is unused: free it */
J
Jan Kara 已提交
3070 3071 3072
	if (vmf->prealloc_pte) {
		pte_free(vmf->vma->vm_mm, vmf->prealloc_pte);
		vmf->prealloc_pte = 0;
3073 3074
	}
	return ret;
3075 3076
}

3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108

/**
 * finish_fault - finish page fault once we have prepared the page to fault
 *
 * @vmf: structure describing the fault
 *
 * This function handles all that is needed to finish a page fault once the
 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
 * given page, adds reverse page mapping, handles memcg charges and LRU
 * addition. The function returns 0 on success, VM_FAULT_ code in case of
 * error.
 *
 * The function expects the page to be locked and on success it consumes a
 * reference of a page being mapped (for the PTE which maps it).
 */
int finish_fault(struct vm_fault *vmf)
{
	struct page *page;
	int ret;

	/* Did we COW the page? */
	if ((vmf->flags & FAULT_FLAG_WRITE) &&
	    !(vmf->vma->vm_flags & VM_SHARED))
		page = vmf->cow_page;
	else
		page = vmf->page;
	ret = alloc_set_pte(vmf, vmf->memcg, page);
	if (vmf->pte)
		pte_unmap_unlock(vmf->pte, vmf->ptl);
	return ret;
}

3109 3110
static unsigned long fault_around_bytes __read_mostly =
	rounddown_pow_of_two(65536);
3111 3112 3113

#ifdef CONFIG_DEBUG_FS
static int fault_around_bytes_get(void *data, u64 *val)
3114
{
3115
	*val = fault_around_bytes;
3116 3117 3118
	return 0;
}

3119 3120 3121 3122 3123
/*
 * 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.
 */
3124
static int fault_around_bytes_set(void *data, u64 val)
3125
{
3126
	if (val / PAGE_SIZE > PTRS_PER_PTE)
3127
		return -EINVAL;
3128 3129 3130 3131
	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 */
3132 3133
	return 0;
}
3134 3135
DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
		fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3136 3137 3138 3139 3140

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

3141 3142
	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
			&fault_around_bytes_fops);
3143
	if (!ret)
3144
		pr_warn("Failed to create fault_around_bytes in debugfs");
3145 3146 3147 3148
	return 0;
}
late_initcall(fault_around_debugfs);
#endif
3149

3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172
/*
 * 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.
 */
3173
static int do_fault_around(struct vm_fault *vmf)
3174
{
J
Jan Kara 已提交
3175
	unsigned long address = vmf->address, nr_pages, mask;
3176
	pgoff_t start_pgoff = vmf->pgoff;
K
Kirill A. Shutemov 已提交
3177
	pgoff_t end_pgoff;
3178
	int off, ret = 0;
3179

3180
	nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3181 3182
	mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;

J
Jan Kara 已提交
3183 3184
	vmf->address = max(address & mask, vmf->vma->vm_start);
	off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
K
Kirill A. Shutemov 已提交
3185
	start_pgoff -= off;
3186 3187

	/*
K
Kirill A. Shutemov 已提交
3188 3189
	 *  end_pgoff is either end of page table or end of vma
	 *  or fault_around_pages() from start_pgoff, depending what is nearest.
3190
	 */
K
Kirill A. Shutemov 已提交
3191
	end_pgoff = start_pgoff -
J
Jan Kara 已提交
3192
		((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3193
		PTRS_PER_PTE - 1;
J
Jan Kara 已提交
3194
	end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
K
Kirill A. Shutemov 已提交
3195
			start_pgoff + nr_pages - 1);
3196

J
Jan Kara 已提交
3197 3198 3199 3200
	if (pmd_none(*vmf->pmd)) {
		vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
						  vmf->address);
		if (!vmf->prealloc_pte)
3201
			goto out;
3202
		smp_wmb(); /* See comment in __pte_alloc() */
3203 3204
	}

J
Jan Kara 已提交
3205
	vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3206 3207

	/* Huge page is mapped? Page fault is solved */
J
Jan Kara 已提交
3208
	if (pmd_trans_huge(*vmf->pmd)) {
3209 3210 3211 3212 3213
		ret = VM_FAULT_NOPAGE;
		goto out;
	}

	/* ->map_pages() haven't done anything useful. Cold page cache? */
J
Jan Kara 已提交
3214
	if (!vmf->pte)
3215 3216 3217
		goto out;

	/* check if the page fault is solved */
J
Jan Kara 已提交
3218 3219
	vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
	if (!pte_none(*vmf->pte))
3220
		ret = VM_FAULT_NOPAGE;
J
Jan Kara 已提交
3221
	pte_unmap_unlock(vmf->pte, vmf->ptl);
K
Kirill A. Shutemov 已提交
3222
out:
J
Jan Kara 已提交
3223 3224
	vmf->address = address;
	vmf->pte = NULL;
3225
	return ret;
3226 3227
}

3228
static int do_read_fault(struct vm_fault *vmf)
3229
{
J
Jan Kara 已提交
3230
	struct vm_area_struct *vma = vmf->vma;
3231 3232 3233 3234 3235 3236 3237
	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).
	 */
3238
	if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3239
		ret = do_fault_around(vmf);
3240 3241
		if (ret)
			return ret;
3242
	}
3243

J
Jan Kara 已提交
3244
	ret = __do_fault(vmf);
3245 3246 3247
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		return ret;

3248
	ret |= finish_fault(vmf);
J
Jan Kara 已提交
3249
	unlock_page(vmf->page);
3250
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
J
Jan Kara 已提交
3251
		put_page(vmf->page);
3252 3253 3254
	return ret;
}

3255
static int do_cow_fault(struct vm_fault *vmf)
3256
{
J
Jan Kara 已提交
3257
	struct vm_area_struct *vma = vmf->vma;
3258 3259 3260 3261 3262
	int ret;

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

J
Jan Kara 已提交
3263 3264
	vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
	if (!vmf->cow_page)
3265 3266
		return VM_FAULT_OOM;

J
Jan Kara 已提交
3267
	if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3268
				&vmf->memcg, false)) {
J
Jan Kara 已提交
3269
		put_page(vmf->cow_page);
3270 3271 3272
		return VM_FAULT_OOM;
	}

J
Jan Kara 已提交
3273
	ret = __do_fault(vmf);
3274 3275
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		goto uncharge_out;
3276 3277
	if (ret & VM_FAULT_DONE_COW)
		return ret;
3278

3279
	if (!(ret & VM_FAULT_DAX_LOCKED))
J
Jan Kara 已提交
3280 3281
		copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
	__SetPageUptodate(vmf->cow_page);
3282

3283
	ret |= finish_fault(vmf);
3284
	if (!(ret & VM_FAULT_DAX_LOCKED)) {
J
Jan Kara 已提交
3285 3286
		unlock_page(vmf->page);
		put_page(vmf->page);
3287
	} else {
3288
		dax_unlock_mapping_entry(vma->vm_file->f_mapping, vmf->pgoff);
3289
	}
3290 3291
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		goto uncharge_out;
3292 3293
	return ret;
uncharge_out:
3294
	mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
J
Jan Kara 已提交
3295
	put_page(vmf->cow_page);
3296 3297 3298
	return ret;
}

3299
static int do_shared_fault(struct vm_fault *vmf)
L
Linus Torvalds 已提交
3300
{
J
Jan Kara 已提交
3301
	struct vm_area_struct *vma = vmf->vma;
3302 3303 3304
	struct address_space *mapping;
	int dirtied = 0;
	int ret, tmp;
3305

J
Jan Kara 已提交
3306
	ret = __do_fault(vmf);
3307
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3308
		return ret;
L
Linus Torvalds 已提交
3309 3310

	/*
3311 3312
	 * Check if the backing address space wants to know that the page is
	 * about to become writable
L
Linus Torvalds 已提交
3313
	 */
3314
	if (vma->vm_ops->page_mkwrite) {
J
Jan Kara 已提交
3315 3316
		unlock_page(vmf->page);
		tmp = do_page_mkwrite(vma, vmf->page, vmf->address);
3317 3318
		if (unlikely(!tmp ||
				(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
J
Jan Kara 已提交
3319
			put_page(vmf->page);
3320
			return tmp;
3321
		}
3322 3323
	}

3324
	ret |= finish_fault(vmf);
3325 3326
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
					VM_FAULT_RETRY))) {
J
Jan Kara 已提交
3327 3328
		unlock_page(vmf->page);
		put_page(vmf->page);
3329
		return ret;
L
Linus Torvalds 已提交
3330
	}
N
Nick Piggin 已提交
3331

J
Jan Kara 已提交
3332
	if (set_page_dirty(vmf->page))
3333
		dirtied = 1;
3334 3335 3336 3337 3338 3339
	/*
	 * 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.
	 */
J
Jan Kara 已提交
3340 3341
	mapping = page_rmapping(vmf->page);
	unlock_page(vmf->page);
3342 3343 3344 3345 3346 3347
	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);
3348
	}
3349

3350
	if (!vma->vm_ops->page_mkwrite)
3351
		file_update_time(vma->vm_file);
N
Nick Piggin 已提交
3352

3353
	return ret;
3354
}
3355

3356 3357 3358 3359 3360 3361
/*
 * 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().
 */
J
Jan Kara 已提交
3362
static int do_fault(struct vm_fault *vmf)
3363
{
J
Jan Kara 已提交
3364
	struct vm_area_struct *vma = vmf->vma;
3365

3366 3367 3368
	/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
	if (!vma->vm_ops->fault)
		return VM_FAULT_SIGBUS;
J
Jan Kara 已提交
3369
	if (!(vmf->flags & FAULT_FLAG_WRITE))
3370
		return do_read_fault(vmf);
3371
	if (!(vma->vm_flags & VM_SHARED))
3372 3373
		return do_cow_fault(vmf);
	return do_shared_fault(vmf);
3374 3375
}

3376
static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3377 3378
				unsigned long addr, int page_nid,
				int *flags)
3379 3380 3381 3382
{
	get_page(page);

	count_vm_numa_event(NUMA_HINT_FAULTS);
3383
	if (page_nid == numa_node_id()) {
3384
		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3385 3386
		*flags |= TNF_FAULT_LOCAL;
	}
3387 3388 3389 3390

	return mpol_misplaced(page, vma, addr);
}

J
Jan Kara 已提交
3391
static int do_numa_page(struct vm_fault *vmf)
3392
{
J
Jan Kara 已提交
3393
	struct vm_area_struct *vma = vmf->vma;
3394
	struct page *page = NULL;
3395
	int page_nid = -1;
3396
	int last_cpupid;
3397
	int target_nid;
3398
	bool migrated = false;
J
Jan Kara 已提交
3399
	pte_t pte = vmf->orig_pte;
3400
	bool was_writable = pte_write(pte);
3401
	int flags = 0;
3402 3403 3404 3405 3406 3407

	/*
	* 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.
	*
3408 3409 3410
	* 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.
3411
	*/
J
Jan Kara 已提交
3412 3413 3414 3415
	vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
	spin_lock(vmf->ptl);
	if (unlikely(!pte_same(*vmf->pte, pte))) {
		pte_unmap_unlock(vmf->pte, vmf->ptl);
3416 3417 3418
		goto out;
	}

3419 3420 3421
	/* Make it present again */
	pte = pte_modify(pte, vma->vm_page_prot);
	pte = pte_mkyoung(pte);
3422 3423
	if (was_writable)
		pte = pte_mkwrite(pte);
J
Jan Kara 已提交
3424 3425
	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
	update_mmu_cache(vma, vmf->address, vmf->pte);
3426

J
Jan Kara 已提交
3427
	page = vm_normal_page(vma, vmf->address, pte);
3428
	if (!page) {
J
Jan Kara 已提交
3429
		pte_unmap_unlock(vmf->pte, vmf->ptl);
3430 3431 3432
		return 0;
	}

3433 3434
	/* TODO: handle PTE-mapped THP */
	if (PageCompound(page)) {
J
Jan Kara 已提交
3435
		pte_unmap_unlock(vmf->pte, vmf->ptl);
3436 3437 3438
		return 0;
	}

3439
	/*
3440 3441 3442 3443 3444 3445
	 * 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.
3446
	 */
3447
	if (!pte_write(pte))
3448 3449
		flags |= TNF_NO_GROUP;

3450 3451 3452 3453 3454 3455 3456
	/*
	 * 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;

3457
	last_cpupid = page_cpupid_last(page);
3458
	page_nid = page_to_nid(page);
J
Jan Kara 已提交
3459
	target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
K
Kirill A. Shutemov 已提交
3460
			&flags);
J
Jan Kara 已提交
3461
	pte_unmap_unlock(vmf->pte, vmf->ptl);
3462 3463 3464 3465 3466 3467
	if (target_nid == -1) {
		put_page(page);
		goto out;
	}

	/* Migrate to the requested node */
3468
	migrated = migrate_misplaced_page(page, vma, target_nid);
3469
	if (migrated) {
3470
		page_nid = target_nid;
3471
		flags |= TNF_MIGRATED;
3472 3473
	} else
		flags |= TNF_MIGRATE_FAIL;
3474 3475

out:
3476
	if (page_nid != -1)
3477
		task_numa_fault(last_cpupid, page_nid, 1, flags);
3478 3479 3480
	return 0;
}

J
Jan Kara 已提交
3481
static int create_huge_pmd(struct vm_fault *vmf)
M
Matthew Wilcox 已提交
3482
{
J
Jan Kara 已提交
3483
	struct vm_area_struct *vma = vmf->vma;
3484
	if (vma_is_anonymous(vma))
J
Jan Kara 已提交
3485
		return do_huge_pmd_anonymous_page(vmf);
M
Matthew Wilcox 已提交
3486
	if (vma->vm_ops->pmd_fault)
J
Jan Kara 已提交
3487 3488
		return vma->vm_ops->pmd_fault(vma, vmf->address, vmf->pmd,
				vmf->flags);
M
Matthew Wilcox 已提交
3489 3490 3491
	return VM_FAULT_FALLBACK;
}

J
Jan Kara 已提交
3492
static int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
M
Matthew Wilcox 已提交
3493
{
J
Jan Kara 已提交
3494 3495 3496 3497 3498
	if (vma_is_anonymous(vmf->vma))
		return do_huge_pmd_wp_page(vmf, orig_pmd);
	if (vmf->vma->vm_ops->pmd_fault)
		return vmf->vma->vm_ops->pmd_fault(vmf->vma, vmf->address,
						   vmf->pmd, vmf->flags);
K
Kirill A. Shutemov 已提交
3499 3500

	/* COW handled on pte level: split pmd */
J
Jan Kara 已提交
3501 3502
	VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
	__split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
K
Kirill A. Shutemov 已提交
3503

M
Matthew Wilcox 已提交
3504 3505 3506
	return VM_FAULT_FALLBACK;
}

3507 3508 3509 3510 3511
static inline bool vma_is_accessible(struct vm_area_struct *vma)
{
	return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
}

L
Linus Torvalds 已提交
3512 3513 3514 3515 3516 3517 3518 3519 3520
/*
 * 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).
 *
3521 3522
 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
 * concurrent faults).
3523
 *
3524 3525
 * 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
3526
 */
J
Jan Kara 已提交
3527
static int handle_pte_fault(struct vm_fault *vmf)
L
Linus Torvalds 已提交
3528 3529 3530
{
	pte_t entry;

J
Jan Kara 已提交
3531
	if (unlikely(pmd_none(*vmf->pmd))) {
3532 3533 3534 3535 3536 3537
		/*
		 * Leave __pte_alloc() until later: because vm_ops->fault may
		 * want to allocate huge page, and if we expose page table
		 * for an instant, it will be difficult to retract from
		 * concurrent faults and from rmap lookups.
		 */
J
Jan Kara 已提交
3538
		vmf->pte = NULL;
3539 3540
	} else {
		/* See comment in pte_alloc_one_map() */
J
Jan Kara 已提交
3541
		if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd))
3542 3543 3544 3545 3546 3547 3548
			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().
		 */
J
Jan Kara 已提交
3549
		vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
J
Jan Kara 已提交
3550
		vmf->orig_pte = *vmf->pte;
3551 3552 3553 3554 3555 3556 3557 3558 3559 3560

		/*
		 * 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.
		 */
		barrier();
J
Jan Kara 已提交
3561
		if (pte_none(vmf->orig_pte)) {
J
Jan Kara 已提交
3562 3563
			pte_unmap(vmf->pte);
			vmf->pte = NULL;
3564
		}
L
Linus Torvalds 已提交
3565 3566
	}

J
Jan Kara 已提交
3567 3568 3569
	if (!vmf->pte) {
		if (vma_is_anonymous(vmf->vma))
			return do_anonymous_page(vmf);
3570
		else
J
Jan Kara 已提交
3571
			return do_fault(vmf);
3572 3573
	}

J
Jan Kara 已提交
3574 3575
	if (!pte_present(vmf->orig_pte))
		return do_swap_page(vmf);
3576

J
Jan Kara 已提交
3577 3578
	if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
		return do_numa_page(vmf);
3579

J
Jan Kara 已提交
3580 3581
	vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
	spin_lock(vmf->ptl);
J
Jan Kara 已提交
3582
	entry = vmf->orig_pte;
J
Jan Kara 已提交
3583
	if (unlikely(!pte_same(*vmf->pte, entry)))
3584
		goto unlock;
J
Jan Kara 已提交
3585
	if (vmf->flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3586
		if (!pte_write(entry))
J
Jan Kara 已提交
3587
			return do_wp_page(vmf);
L
Linus Torvalds 已提交
3588 3589 3590
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
J
Jan Kara 已提交
3591 3592 3593
	if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
				vmf->flags & FAULT_FLAG_WRITE)) {
		update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3594 3595 3596 3597 3598 3599 3600
	} 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.
		 */
J
Jan Kara 已提交
3601 3602
		if (vmf->flags & FAULT_FLAG_WRITE)
			flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3603
	}
3604
unlock:
J
Jan Kara 已提交
3605
	pte_unmap_unlock(vmf->pte, vmf->ptl);
N
Nick Piggin 已提交
3606
	return 0;
L
Linus Torvalds 已提交
3607 3608 3609 3610
}

/*
 * By the time we get here, we already hold the mm semaphore
3611 3612 3613
 *
 * 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
3614
 */
3615 3616
static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
		unsigned int flags)
L
Linus Torvalds 已提交
3617
{
J
Jan Kara 已提交
3618
	struct vm_fault vmf = {
K
Kirill A. Shutemov 已提交
3619
		.vma = vma,
3620
		.address = address & PAGE_MASK,
K
Kirill A. Shutemov 已提交
3621
		.flags = flags,
3622
		.pgoff = linear_page_index(vma, address),
3623
		.gfp_mask = __get_fault_gfp_mask(vma),
K
Kirill A. Shutemov 已提交
3624
	};
3625
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
3626 3627 3628 3629 3630 3631
	pgd_t *pgd;
	pud_t *pud;

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3632
		return VM_FAULT_OOM;
J
Jan Kara 已提交
3633 3634
	vmf.pmd = pmd_alloc(mm, pud, address);
	if (!vmf.pmd)
H
Hugh Dickins 已提交
3635
		return VM_FAULT_OOM;
J
Jan Kara 已提交
3636 3637
	if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
		int ret = create_huge_pmd(&vmf);
3638 3639
		if (!(ret & VM_FAULT_FALLBACK))
			return ret;
3640
	} else {
J
Jan Kara 已提交
3641
		pmd_t orig_pmd = *vmf.pmd;
3642 3643
		int ret;

3644
		barrier();
3645
		if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3646
			if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
J
Jan Kara 已提交
3647
				return do_huge_pmd_numa_page(&vmf, orig_pmd);
3648

J
Jan Kara 已提交
3649
			if ((vmf.flags & FAULT_FLAG_WRITE) &&
K
Kirill A. Shutemov 已提交
3650
					!pmd_write(orig_pmd)) {
J
Jan Kara 已提交
3651
				ret = wp_huge_pmd(&vmf, orig_pmd);
3652 3653
				if (!(ret & VM_FAULT_FALLBACK))
					return ret;
3654
			} else {
J
Jan Kara 已提交
3655
				huge_pmd_set_accessed(&vmf, orig_pmd);
3656
				return 0;
3657
			}
3658 3659 3660
		}
	}

J
Jan Kara 已提交
3661
	return handle_pte_fault(&vmf);
L
Linus Torvalds 已提交
3662 3663
}

3664 3665 3666 3667 3668 3669
/*
 * 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().
 */
3670 3671
int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
		unsigned int flags)
3672 3673 3674 3675 3676 3677
{
	int ret;

	__set_current_state(TASK_RUNNING);

	count_vm_event(PGFAULT);
3678
	mem_cgroup_count_vm_event(vma->vm_mm, PGFAULT);
3679 3680 3681 3682 3683 3684 3685 3686 3687

	/* 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)
3688
		mem_cgroup_oom_enable();
3689

K
Kirill A. Shutemov 已提交
3690 3691 3692 3693 3694 3695 3696 3697 3698
	if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
					    flags & FAULT_FLAG_INSTRUCTION,
					    flags & FAULT_FLAG_REMOTE))
		return VM_FAULT_SIGSEGV;

	if (unlikely(is_vm_hugetlb_page(vma)))
		ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
	else
		ret = __handle_mm_fault(vma, address, flags);
3699

3700 3701 3702 3703 3704 3705 3706 3707 3708 3709 3710
	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);
	}
3711

3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 3722 3723 3724
	/*
	 * This mm has been already reaped by the oom reaper and so the
	 * refault cannot be trusted in general. Anonymous refaults would
	 * lose data and give a zero page instead e.g. This is especially
	 * problem for use_mm() because regular tasks will just die and
	 * the corrupted data will not be visible anywhere while kthread
	 * will outlive the oom victim and potentially propagate the date
	 * further.
	 */
	if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
				&& test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
		ret = VM_FAULT_SIGBUS;

3725 3726
	return ret;
}
3727
EXPORT_SYMBOL_GPL(handle_mm_fault);
3728

L
Linus Torvalds 已提交
3729 3730 3731
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3732
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3733
 */
3734
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3735
{
H
Hugh Dickins 已提交
3736 3737
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3738
		return -ENOMEM;
L
Linus Torvalds 已提交
3739

3740 3741
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3742
	spin_lock(&mm->page_table_lock);
3743
	if (pgd_present(*pgd))		/* Another has populated it */
3744
		pud_free(mm, new);
3745 3746
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3747
	spin_unlock(&mm->page_table_lock);
3748
	return 0;
L
Linus Torvalds 已提交
3749 3750 3751 3752 3753 3754
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3755
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3756
 */
3757
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3758
{
H
Hugh Dickins 已提交
3759 3760
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3761
		return -ENOMEM;
L
Linus Torvalds 已提交
3762

3763 3764
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3765
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3766
#ifndef __ARCH_HAS_4LEVEL_HACK
3767 3768
	if (!pud_present(*pud)) {
		mm_inc_nr_pmds(mm);
3769
		pud_populate(mm, pud, new);
3770
	} else	/* Another has populated it */
3771
		pmd_free(mm, new);
3772 3773 3774
#else
	if (!pgd_present(*pud)) {
		mm_inc_nr_pmds(mm);
3775
		pgd_populate(mm, pud, new);
3776 3777
	} else /* Another has populated it */
		pmd_free(mm, new);
L
Linus Torvalds 已提交
3778
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3779
	spin_unlock(&mm->page_table_lock);
3780
	return 0;
3781
}
L
Linus Torvalds 已提交
3782 3783
#endif /* __PAGETABLE_PMD_FOLDED */

3784
static int __follow_pte(struct mm_struct *mm, unsigned long address,
J
Johannes Weiner 已提交
3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796 3797 3798 3799 3800
		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);
3801
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3802 3803 3804 3805 3806 3807 3808 3809 3810 3811 3812 3813 3814 3815 3816 3817 3818 3819 3820 3821
	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;
}

3822 3823 3824 3825 3826 3827 3828 3829 3830 3831 3832
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
3833 3834 3835 3836 3837 3838 3839 3840 3841 3842 3843 3844 3845 3846 3847 3848 3849 3850 3851 3852 3853 3854 3855 3856 3857 3858 3859 3860 3861
/**
 * 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);

3862
#ifdef CONFIG_HAVE_IOREMAP_PROT
3863 3864 3865
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3866
{
3867
	int ret = -EINVAL;
3868 3869 3870
	pte_t *ptep, pte;
	spinlock_t *ptl;

3871 3872
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3873

3874
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3875
		goto out;
3876
	pte = *ptep;
3877

3878 3879 3880 3881
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3882
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3883

3884
	ret = 0;
3885 3886 3887
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3888
	return ret;
3889 3890 3891 3892 3893 3894 3895
}

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
3896
	void __iomem *maddr;
3897 3898
	int offset = addr & (PAGE_SIZE-1);

3899
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3900 3901
		return -EINVAL;

3902
	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
3903 3904 3905 3906 3907 3908 3909 3910
	if (write)
		memcpy_toio(maddr + offset, buf, len);
	else
		memcpy_fromio(buf, maddr + offset, len);
	iounmap(maddr);

	return len;
}
3911
EXPORT_SYMBOL_GPL(generic_access_phys);
3912 3913
#endif

3914
/*
3915 3916
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
3917
 */
3918
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3919
		unsigned long addr, void *buf, int len, unsigned int gup_flags)
3920 3921 3922
{
	struct vm_area_struct *vma;
	void *old_buf = buf;
3923
	int write = gup_flags & FOLL_WRITE;
3924 3925

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3926
	/* ignore errors, just check how much was successfully transferred */
3927 3928 3929
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3930
		struct page *page = NULL;
3931

3932
		ret = get_user_pages_remote(tsk, mm, addr, 1,
3933
				gup_flags, &page, &vma, NULL);
3934
		if (ret <= 0) {
3935 3936 3937
#ifndef CONFIG_HAVE_IOREMAP_PROT
			break;
#else
3938 3939 3940 3941 3942
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
			vma = find_vma(mm, addr);
3943
			if (!vma || vma->vm_start > addr)
3944 3945 3946 3947 3948 3949 3950
				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;
3951
#endif
3952
		} else {
3953 3954 3955 3956 3957 3958 3959 3960 3961 3962 3963 3964 3965 3966 3967
			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);
3968
			put_page(page);
3969 3970 3971 3972 3973 3974 3975 3976 3977
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
3978

S
Stephen Wilson 已提交
3979
/**
3980
 * access_remote_vm - access another process' address space
S
Stephen Wilson 已提交
3981 3982 3983 3984
 * @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
3985
 * @gup_flags:	flags modifying lookup behaviour
S
Stephen Wilson 已提交
3986 3987 3988 3989
 *
 * The caller must hold a reference on @mm.
 */
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3990
		void *buf, int len, unsigned int gup_flags)
S
Stephen Wilson 已提交
3991
{
3992
	return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
S
Stephen Wilson 已提交
3993 3994
}

3995 3996 3997 3998 3999 4000
/*
 * 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,
4001
		void *buf, int len, unsigned int gup_flags)
4002 4003 4004 4005 4006 4007 4008 4009
{
	struct mm_struct *mm;
	int ret;

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

4010
	ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4011

4012 4013 4014 4015
	mmput(mm);

	return ret;
}
4016
EXPORT_SYMBOL_GPL(access_process_vm);
4017

4018 4019 4020 4021 4022 4023 4024 4025
/*
 * 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;

4026 4027 4028 4029 4030 4031 4032
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

4033 4034 4035 4036 4037 4038
	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
4039
			char *p;
4040

M
Miklos Szeredi 已提交
4041
			p = file_path(f, buf, PAGE_SIZE);
4042 4043
			if (IS_ERR(p))
				p = "?";
A
Andy Shevchenko 已提交
4044
			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4045 4046 4047 4048 4049
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
4050
	up_read(&mm->mmap_sem);
4051
}
4052

4053
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4054
void __might_fault(const char *file, int line)
4055
{
4056 4057 4058 4059 4060 4061 4062 4063
	/*
	 * 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;
4064
	if (pagefault_disabled())
4065
		return;
4066 4067
	__might_sleep(file, line, 0);
#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4068
	if (current->mm)
4069
		might_lock_read(&current->mm->mmap_sem);
4070
#endif
4071
}
4072
EXPORT_SYMBOL(__might_fault);
4073
#endif
A
Andrea Arcangeli 已提交
4074 4075 4076 4077 4078 4079 4080 4081 4082 4083 4084 4085 4086 4087 4088 4089 4090 4091 4092 4093 4094 4095 4096 4097 4098 4099 4100 4101 4102 4103 4104 4105 4106 4107 4108 4109 4110 4111 4112 4113 4114 4115 4116 4117 4118 4119 4120 4121 4122 4123 4124 4125 4126 4127 4128 4129 4130 4131 4132 4133 4134 4135 4136 4137 4138 4139 4140 4141 4142 4143 4144

#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 */
4145

4146
#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4147 4148 4149 4150 4151 4152 4153 4154 4155

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);
}

4156
bool ptlock_alloc(struct page *page)
4157 4158 4159
{
	spinlock_t *ptl;

4160
	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4161 4162
	if (!ptl)
		return false;
4163
	page->ptl = ptl;
4164 4165 4166
	return true;
}

4167
void ptlock_free(struct page *page)
4168
{
4169
	kmem_cache_free(page_ptl_cachep, page->ptl);
4170 4171
}
#endif