memory.c 114.2 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.
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 *              Idea by Alex Bligh (alex@cconcepts.co.uk)
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 *
 * 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>
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#include <linux/uaccess.h>
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#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;
EXPORT_SYMBOL(max_mapnr);
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struct page *mem_map;
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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.
 */
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void *high_memory;
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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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EXPORT_SYMBOL(zero_pfn);

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unsigned long highest_memmap_pfn __read_mostly;

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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,
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				floor, next ? next->vm_start : ceiling);
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		}
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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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}

611
int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
L
Linus Torvalds 已提交
612
{
613 614 615 616
	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
	if (!new)
		return -ENOMEM;

617 618
	smp_wmb(); /* See comment in __pte_alloc */

619
	spin_lock(&init_mm.page_table_lock);
620
	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
621
		pmd_populate_kernel(&init_mm, pmd, new);
622
		new = NULL;
623
	}
624
	spin_unlock(&init_mm.page_table_lock);
625 626
	if (new)
		pte_free_kernel(&init_mm, new);
627
	return 0;
L
Linus Torvalds 已提交
628 629
}

K
KAMEZAWA Hiroyuki 已提交
630 631 632 633 634 635
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)
636
{
K
KAMEZAWA Hiroyuki 已提交
637 638
	int i;

639
	if (current->mm == mm)
640
		sync_mm_rss(mm);
K
KAMEZAWA Hiroyuki 已提交
641 642 643
	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
644 645
}

N
Nick Piggin 已提交
646
/*
647 648 649
 * 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
650 651 652
 *
 * The calling function must still handle the error.
 */
653 654
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
655
{
656 657 658 659 660
	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;
661 662 663 664 665 666 667 668 669 670 671 672 673 674
	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) {
675 676
			pr_alert("BUG: Bad page map: %lu messages suppressed\n",
				 nr_unshown);
677 678 679 680 681 682
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
683 684 685 686

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

687 688 689
	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));
690
	if (page)
691
		dump_page(page, "bad pte");
692 693
	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);
694 695 696
	/*
	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
	 */
697 698 699 700 701
	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
702
	dump_stack();
703
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
N
Nick Piggin 已提交
704 705
}

H
Hugh Dickins 已提交
706
/*
N
Nick Piggin 已提交
707
 * vm_normal_page -- This function gets the "struct page" associated with a pte.
708
 *
N
Nick Piggin 已提交
709 710 711
 * "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
712
 *
N
Nick Piggin 已提交
713 714 715 716 717 718 719 720
 * 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.
721
 *
J
Jared Hulbert 已提交
722 723
 * 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
724 725
 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
726 727 728
 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
N
Nick Piggin 已提交
729 730 731 732 733 734
 * 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
735 736
 *
 *
N
Nick Piggin 已提交
737
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
738 739 740 741 742 743 744 745 746
 *
 * 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
747
 */
N
Nick Piggin 已提交
748 749 750 751 752 753 754
#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
755
{
756
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
757 758

	if (HAVE_PTE_SPECIAL) {
759
		if (likely(!pte_special(pte)))
760
			goto check_pfn;
761 762
		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
763 764
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
765
		if (!is_zero_pfn(pfn))
766
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
767 768 769 770 771
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
772 773 774 775 776 777
	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
778 779
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
780 781 782 783 784
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
785 786
	}

787 788
	if (is_zero_pfn(pfn))
		return NULL;
789 790 791 792 793
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
794 795

	/*
N
Nick Piggin 已提交
796 797
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
798
	 */
J
Jared Hulbert 已提交
799
out:
800
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
801 802
}

803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842
#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
843 844 845 846 847 848
/*
 * 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
849
static inline unsigned long
L
Linus Torvalds 已提交
850
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
851
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
852
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
853
{
N
Nick Piggin 已提交
854
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
855 856 857 858 859
	pte_t pte = *src_pte;
	struct page *page;

	/* pte contains position in swap or file, so copy. */
	if (unlikely(!pte_present(pte))) {
860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877
		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);

878
			rss[mm_counter(page)]++;
879 880 881 882 883 884 885 886 887 888 889 890

			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);
891
			}
L
Linus Torvalds 已提交
892
		}
893
		goto out_set_pte;
L
Linus Torvalds 已提交
894 895 896 897 898 899
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
900
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
901
		ptep_set_wrprotect(src_mm, addr, src_pte);
902
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
903 904 905 906 907 908 909 910 911
	}

	/*
	 * 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);
912 913 914 915

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
916
		page_dup_rmap(page, false);
917
		rss[mm_counter(page)]++;
918
	}
919 920 921

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
922
	return 0;
L
Linus Torvalds 已提交
923 924
}

925
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
926 927
		   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
928
{
929
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
930
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
931
	spinlock_t *src_ptl, *dst_ptl;
932
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
933
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
934
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
935 936

again:
K
KAMEZAWA Hiroyuki 已提交
937 938
	init_rss_vec(rss);

H
Hugh Dickins 已提交
939
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
940 941
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
942
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
943
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
944
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
945 946
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
947
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
948 949 950 951 952 953

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
954 955 956
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
957
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
958 959
				break;
		}
L
Linus Torvalds 已提交
960 961 962 963
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
964 965 966 967
		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
968 969 970
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

971
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
972
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
973
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
974
	add_mm_rss_vec(dst_mm, rss);
975
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
976
	cond_resched();
H
Hugh Dickins 已提交
977 978 979 980 981 982

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000
	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);
1001
		if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
1002
			int err;
1003
			VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1004 1005 1006 1007 1008 1009 1010 1011
			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
1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033
		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);
1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045
		if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
			int err;

			VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
			err = copy_huge_pud(dst_mm, src_mm,
					    dst_pud, src_pud, addr, vma);
			if (err == -ENOMEM)
				return -ENOMEM;
			if (!err)
				continue;
			/* fall through */
		}
L
Linus Torvalds 已提交
1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
		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;
1062 1063 1064
	unsigned long mmun_start;	/* For mmu_notifiers */
	unsigned long mmun_end;		/* For mmu_notifiers */
	bool is_cow;
A
Andrea Arcangeli 已提交
1065
	int ret;
L
Linus Torvalds 已提交
1066

1067 1068 1069 1070 1071 1072
	/*
	 * 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.
	 */
1073 1074 1075
	if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
			!vma->anon_vma)
		return 0;
1076

L
Linus Torvalds 已提交
1077 1078 1079
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

1080
	if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1081 1082 1083 1084
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
1085
		ret = track_pfn_copy(vma);
1086 1087 1088 1089
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
1090 1091 1092 1093 1094 1095
	/*
	 * 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.
	 */
1096 1097 1098 1099 1100 1101
	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
1102 1103

	ret = 0;
L
Linus Torvalds 已提交
1104 1105 1106 1107 1108 1109
	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
1110 1111 1112 1113 1114
		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
1115
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
1116

1117 1118
	if (is_cow)
		mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
A
Andrea Arcangeli 已提交
1119
	return ret;
L
Linus Torvalds 已提交
1120 1121
}

1122
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1123
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
1124
				unsigned long addr, unsigned long end,
1125
				struct zap_details *details)
L
Linus Torvalds 已提交
1126
{
N
Nick Piggin 已提交
1127
	struct mm_struct *mm = tlb->mm;
P
Peter Zijlstra 已提交
1128
	int force_flush = 0;
K
KAMEZAWA Hiroyuki 已提交
1129
	int rss[NR_MM_COUNTERS];
1130
	spinlock_t *ptl;
1131
	pte_t *start_pte;
1132
	pte_t *pte;
1133
	swp_entry_t entry;
K
KAMEZAWA Hiroyuki 已提交
1134

1135
	tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
P
Peter Zijlstra 已提交
1136
again:
1137
	init_rss_vec(rss);
1138 1139
	start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	pte = start_pte;
1140
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1141 1142
	do {
		pte_t ptent = *pte;
T
Tobin C Harding 已提交
1143
		if (pte_none(ptent))
L
Linus Torvalds 已提交
1144
			continue;
1145

L
Linus Torvalds 已提交
1146
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
1147
			struct page *page;
1148

1149
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
1150 1151 1152 1153 1154 1155 1156
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
1157
				    details->check_mapping != page_rmapping(page))
L
Linus Torvalds 已提交
1158 1159
					continue;
			}
N
Nick Piggin 已提交
1160
			ptent = ptep_get_and_clear_full(mm, addr, pte,
1161
							tlb->fullmm);
L
Linus Torvalds 已提交
1162 1163 1164
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
1165 1166

			if (!PageAnon(page)) {
1167 1168
				if (pte_dirty(ptent)) {
					force_flush = 1;
1169
					set_page_dirty(page);
1170
				}
1171
				if (pte_young(ptent) &&
1172
				    likely(!(vma->vm_flags & VM_SEQ_READ)))
1173
					mark_page_accessed(page);
1174
			}
1175
			rss[mm_counter(page)]--;
1176
			page_remove_rmap(page, false);
1177 1178
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
1179
			if (unlikely(__tlb_remove_page(tlb, page))) {
1180
				force_flush = 1;
1181
				addr += PAGE_SIZE;
P
Peter Zijlstra 已提交
1182
				break;
1183
			}
L
Linus Torvalds 已提交
1184 1185
			continue;
		}
1186 1187
		/* If details->check_mapping, we leave swap entries. */
		if (unlikely(details))
L
Linus Torvalds 已提交
1188
			continue;
K
KAMEZAWA Hiroyuki 已提交
1189

1190 1191 1192 1193 1194
		entry = pte_to_swp_entry(ptent);
		if (!non_swap_entry(entry))
			rss[MM_SWAPENTS]--;
		else if (is_migration_entry(entry)) {
			struct page *page;
1195

1196
			page = migration_entry_to_page(entry);
1197
			rss[mm_counter(page)]--;
K
KAMEZAWA Hiroyuki 已提交
1198
		}
1199 1200
		if (unlikely(!free_swap_and_cache(entry)))
			print_bad_pte(vma, addr, ptent, NULL);
1201
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1202
	} while (pte++, addr += PAGE_SIZE, addr != end);
1203

K
KAMEZAWA Hiroyuki 已提交
1204
	add_mm_rss_vec(mm, rss);
1205
	arch_leave_lazy_mmu_mode();
1206

1207
	/* Do the actual TLB flush before dropping ptl */
1208
	if (force_flush)
1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220
		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);
1221
		if (addr != end)
P
Peter Zijlstra 已提交
1222 1223 1224
			goto again;
	}

1225
	return addr;
L
Linus Torvalds 已提交
1226 1227
}

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

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1239
		if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1240
			if (next - addr != HPAGE_PMD_SIZE) {
1241 1242
				VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
				    !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1243
				__split_huge_pmd(vma, pmd, addr, false, NULL);
S
Shaohua Li 已提交
1244
			} else if (zap_huge_pmd(tlb, vma, pmd, addr))
1245
				goto next;
1246 1247
			/* fall through */
		}
1248 1249 1250 1251 1252 1253 1254 1255 1256
		/*
		 * 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;
1257
		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1258
next:
1259 1260
		cond_resched();
	} while (pmd++, addr = next, addr != end);
1261 1262

	return addr;
L
Linus Torvalds 已提交
1263 1264
}

1265
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1266
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1267
				unsigned long addr, unsigned long end,
1268
				struct zap_details *details)
L
Linus Torvalds 已提交
1269 1270 1271 1272 1273 1274 1275
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1276 1277 1278 1279 1280 1281 1282 1283
		if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
			if (next - addr != HPAGE_PUD_SIZE) {
				VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
				split_huge_pud(vma, pud, addr);
			} else if (zap_huge_pud(tlb, vma, pud, addr))
				goto next;
			/* fall through */
		}
1284
		if (pud_none_or_clear_bad(pud))
L
Linus Torvalds 已提交
1285
			continue;
1286
		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1287 1288
next:
		cond_resched();
1289
	} while (pud++, addr = next, addr != end);
1290 1291

	return addr;
L
Linus Torvalds 已提交
1292 1293
}

M
Michal Hocko 已提交
1294
void unmap_page_range(struct mmu_gather *tlb,
A
Al Viro 已提交
1295 1296 1297
			     struct vm_area_struct *vma,
			     unsigned long addr, unsigned long end,
			     struct zap_details *details)
L
Linus Torvalds 已提交
1298 1299 1300 1301 1302 1303 1304 1305 1306
{
	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);
1307
		if (pgd_none_or_clear_bad(pgd))
L
Linus Torvalds 已提交
1308
			continue;
1309 1310
		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
	} while (pgd++, addr = next, addr != end);
L
Linus Torvalds 已提交
1311 1312
	tlb_end_vma(tlb, vma);
}
1313

1314 1315 1316

static void unmap_single_vma(struct mmu_gather *tlb,
		struct vm_area_struct *vma, unsigned long start_addr,
1317
		unsigned long end_addr,
1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328
		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;

1329 1330 1331
	if (vma->vm_file)
		uprobe_munmap(vma, start, end);

1332
	if (unlikely(vma->vm_flags & VM_PFNMAP))
1333
		untrack_pfn(vma, 0, 0);
1334 1335 1336 1337 1338 1339 1340

	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
1341
			 * cleanup path of mmap_region. When
1342
			 * hugetlbfs ->mmap method fails,
1343
			 * mmap_region() nullifies vma->vm_file
1344 1345 1346 1347
			 * before calling this function to clean up.
			 * Since no pte has actually been setup, it is
			 * safe to do nothing in this case.
			 */
1348
			if (vma->vm_file) {
1349
				i_mmap_lock_write(vma->vm_file->f_mapping);
1350
				__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1351
				i_mmap_unlock_write(vma->vm_file->f_mapping);
1352
			}
1353 1354 1355
		} else
			unmap_page_range(tlb, vma, start, end, details);
	}
L
Linus Torvalds 已提交
1356 1357 1358 1359
}

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
1360
 * @tlb: address of the caller's struct mmu_gather
L
Linus Torvalds 已提交
1361 1362 1363 1364
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 *
1365
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1366 1367 1368 1369 1370 1371 1372 1373 1374 1375
 *
 * 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
1376
void unmap_vmas(struct mmu_gather *tlb,
L
Linus Torvalds 已提交
1377
		struct vm_area_struct *vma, unsigned long start_addr,
1378
		unsigned long end_addr)
L
Linus Torvalds 已提交
1379
{
A
Andrea Arcangeli 已提交
1380
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1381

A
Andrea Arcangeli 已提交
1382
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1383
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1384
		unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
A
Andrea Arcangeli 已提交
1385
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1386 1387 1388 1389 1390
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
1391
 * @start: starting address of pages to zap
L
Linus Torvalds 已提交
1392
 * @size: number of bytes to zap
1393 1394
 *
 * Caller must protect the VMA list
L
Linus Torvalds 已提交
1395
 */
1396
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1397
		unsigned long size)
L
Linus Torvalds 已提交
1398 1399
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1400
	struct mmu_gather tlb;
1401
	unsigned long end = start + size;
L
Linus Torvalds 已提交
1402 1403

	lru_add_drain();
1404
	tlb_gather_mmu(&tlb, mm, start, end);
1405
	update_hiwater_rss(mm);
1406 1407
	mmu_notifier_invalidate_range_start(mm, start, end);
	for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1408
		unmap_single_vma(&tlb, vma, start, end, NULL);
1409 1410
	mmu_notifier_invalidate_range_end(mm, start, end);
	tlb_finish_mmu(&tlb, start, end);
L
Linus Torvalds 已提交
1411 1412
}

1413 1414 1415 1416 1417
/**
 * 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
1418
 * @details: details of shared cache invalidation
1419 1420
 *
 * The range must fit into one VMA.
L
Linus Torvalds 已提交
1421
 */
1422
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1423 1424 1425
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
P
Peter Zijlstra 已提交
1426
	struct mmu_gather tlb;
L
Linus Torvalds 已提交
1427 1428 1429
	unsigned long end = address + size;

	lru_add_drain();
1430
	tlb_gather_mmu(&tlb, mm, address, end);
1431
	update_hiwater_rss(mm);
1432
	mmu_notifier_invalidate_range_start(mm, address, end);
1433
	unmap_single_vma(&tlb, vma, address, end, details);
1434
	mmu_notifier_invalidate_range_end(mm, address, end);
P
Peter Zijlstra 已提交
1435
	tlb_finish_mmu(&tlb, address, end);
L
Linus Torvalds 已提交
1436 1437
}

1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455
/**
 * 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;
1456
	zap_page_range_single(vma, address, size, NULL);
1457 1458 1459 1460
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

1461
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
1462
			spinlock_t **ptl)
1463
{
T
Tobin C Harding 已提交
1464 1465
	pgd_t *pgd = pgd_offset(mm, addr);
	pud_t *pud = pud_alloc(mm, pgd, addr);
1466
	if (pud) {
T
Tobin C Harding 已提交
1467
		pmd_t *pmd = pmd_alloc(mm, pud, addr);
1468 1469
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
1470
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1471
		}
1472 1473 1474 1475
	}
	return NULL;
}

1476 1477 1478 1479 1480 1481 1482
/*
 * 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
1483 1484
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1485
{
N
Nick Piggin 已提交
1486
	struct mm_struct *mm = vma->vm_mm;
1487
	int retval;
1488
	pte_t *pte;
1489 1490
	spinlock_t *ptl;

1491
	retval = -EINVAL;
1492
	if (PageAnon(page))
1493
		goto out;
1494 1495
	retval = -ENOMEM;
	flush_dcache_page(page);
1496
	pte = get_locked_pte(mm, addr, &ptl);
1497
	if (!pte)
1498
		goto out;
1499 1500 1501 1502 1503 1504
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
1505
	inc_mm_counter_fast(mm, mm_counter_file(page));
K
Kirill A. Shutemov 已提交
1506
	page_add_file_rmap(page, false);
1507 1508 1509
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1510 1511
	pte_unmap_unlock(pte, ptl);
	return retval;
1512 1513 1514 1515 1516 1517
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1518 1519 1520 1521 1522 1523
/**
 * 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
 *
1524 1525 1526 1527 1528 1529
 * 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
1530
 * (see split_page()).
1531 1532 1533 1534 1535 1536 1537 1538
 *
 * 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.
1539 1540 1541 1542 1543
 *
 * 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.
1544
 */
N
Nick Piggin 已提交
1545 1546
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1547 1548 1549 1550 1551
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1552 1553 1554 1555 1556
	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
1557
	return insert_page(vma, addr, page, vma->vm_page_prot);
1558
}
1559
EXPORT_SYMBOL(vm_insert_page);
1560

N
Nick Piggin 已提交
1561
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1562
			pfn_t pfn, pgprot_t prot)
N
Nick Piggin 已提交
1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577
{
	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.. */
1578 1579 1580 1581
	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
1582
	set_pte_at(mm, addr, pte, entry);
1583
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1584 1585 1586 1587 1588 1589 1590 1591

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

N
Nick Piggin 已提交
1592 1593 1594 1595 1596 1597
/**
 * 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
 *
1598
 * Similar to vm_insert_page, this allows drivers to insert individual pages
N
Nick Piggin 已提交
1599 1600 1601 1602
 * 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
1603 1604 1605 1606 1607
 *
 * 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
1608 1609
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1610
			unsigned long pfn)
A
Andy Lutomirski 已提交
1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632
{
	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
1633
{
1634
	int ret;
N
Nick Piggin 已提交
1635 1636 1637 1638 1639 1640
	/*
	 * 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
1641 1642 1643 1644 1645
	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
1646

N
Nick Piggin 已提交
1647 1648
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1649 1650

	track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1651

1652
	ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
1653 1654

	return ret;
N
Nick Piggin 已提交
1655
}
A
Andy Lutomirski 已提交
1656
EXPORT_SYMBOL(vm_insert_pfn_prot);
N
Nick Piggin 已提交
1657

N
Nick Piggin 已提交
1658
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1659
			pfn_t pfn)
N
Nick Piggin 已提交
1660
{
1661 1662
	pgprot_t pgprot = vma->vm_page_prot;

N
Nick Piggin 已提交
1663
	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
N
Nick Piggin 已提交
1664

N
Nick Piggin 已提交
1665 1666
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1667 1668

	track_pfn_insert(vma, &pgprot, pfn);
N
Nick Piggin 已提交
1669

N
Nick Piggin 已提交
1670 1671 1672 1673
	/*
	 * 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
1674 1675
	 * 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
1676
	 */
1677
	if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
N
Nick Piggin 已提交
1678 1679
		struct page *page;

1680 1681 1682 1683 1684 1685
		/*
		 * 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));
1686
		return insert_page(vma, addr, page, pgprot);
N
Nick Piggin 已提交
1687
	}
1688
	return insert_pfn(vma, addr, pfn, pgprot);
N
Nick Piggin 已提交
1689
}
N
Nick Piggin 已提交
1690
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1691

L
Linus Torvalds 已提交
1692 1693 1694 1695 1696 1697 1698 1699 1700 1701
/*
 * 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
1702
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1703

H
Hugh Dickins 已提交
1704
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1705 1706
	if (!pte)
		return -ENOMEM;
1707
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1708 1709
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1710
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1711 1712
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1713
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1714
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728
	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;
1729
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758
	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;
}

1759 1760 1761 1762 1763 1764 1765 1766 1767 1768
/**
 * 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
1769 1770 1771 1772 1773
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;
1774
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1775
	struct mm_struct *mm = vma->vm_mm;
1776
	unsigned long remap_pfn = pfn;
L
Linus Torvalds 已提交
1777 1778 1779 1780 1781 1782 1783
	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).
1784 1785 1786
	 *   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.
1787 1788 1789 1790
	 *   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
1791 1792 1793 1794
	 *
	 * 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".
1795
	 * See vm_normal_page() for details.
L
Linus Torvalds 已提交
1796
	 */
1797 1798 1799
	if (is_cow_mapping(vma->vm_flags)) {
		if (addr != vma->vm_start || end != vma->vm_end)
			return -EINVAL;
L
Linus Torvalds 已提交
1800
		vma->vm_pgoff = pfn;
1801 1802
	}

1803
	err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
1804
	if (err)
1805
		return -EINVAL;
L
Linus Torvalds 已提交
1806

1807
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
L
Linus Torvalds 已提交
1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819

	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);
1820 1821

	if (err)
1822
		untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
1823

L
Linus Torvalds 已提交
1824 1825 1826 1827
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

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 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874
/**
 * 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);

1875 1876 1877 1878 1879 1880
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;
1881
	pgtable_t token;
1882
	spinlock_t *uninitialized_var(ptl);
1883 1884 1885 1886 1887 1888 1889 1890 1891

	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));

1892 1893
	arch_enter_lazy_mmu_mode();

1894
	token = pmd_pgtable(*pmd);
1895 1896

	do {
1897
		err = fn(pte++, token, addr, data);
1898 1899
		if (err)
			break;
1900
	} while (addr += PAGE_SIZE, addr != end);
1901

1902 1903
	arch_leave_lazy_mmu_mode();

1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916
	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
1917 1918
	BUG_ON(pud_huge(*pud));

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 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959
	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;
1960
	unsigned long end = addr + size;
1961 1962
	int err;

1963 1964 1965
	if (WARN_ON(addr >= end))
		return -EINVAL;

1966 1967 1968 1969 1970 1971 1972
	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);
1973

1974 1975 1976 1977
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

1978
/*
1979 1980 1981 1982 1983
 * 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;
1984
 * and do_anonymous_page can safely check later on).
1985
 */
H
Hugh Dickins 已提交
1986
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1987 1988 1989 1990 1991
				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
1992 1993
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
1994
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
1995
		spin_unlock(ptl);
1996 1997 1998 1999 2000 2001
	}
#endif
	pte_unmap(page_table);
	return same;
}

2002
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2003
{
2004 2005
	debug_dma_assert_idle(src);

2006 2007 2008 2009 2010 2011 2012
	/*
	 * 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)) {
2013
		void *kaddr = kmap_atomic(dst);
L
Linus Torvalds 已提交
2014 2015 2016 2017 2018 2019 2020 2021 2022
		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))
2023
			clear_page(kaddr);
2024
		kunmap_atomic(kaddr);
2025
		flush_dcache_page(dst);
N
Nick Piggin 已提交
2026 2027
	} else
		copy_user_highpage(dst, src, va, vma);
2028 2029
}

2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043
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;
}

2044 2045 2046 2047 2048 2049
/*
 * 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.
 */
2050
static int do_page_mkwrite(struct vm_fault *vmf)
2051 2052
{
	int ret;
2053 2054
	struct page *page = vmf->page;
	unsigned int old_flags = vmf->flags;
2055

2056
	vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2057

2058
	ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2059 2060
	/* Restore original flags so that caller is not surprised */
	vmf->flags = old_flags;
2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074
	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;
}

2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109
/*
 * Handle dirtying of a page in shared file mapping on a write fault.
 *
 * The function expects the page to be locked and unlocks it.
 */
static void fault_dirty_shared_page(struct vm_area_struct *vma,
				    struct page *page)
{
	struct address_space *mapping;
	bool dirtied;
	bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;

	dirtied = set_page_dirty(page);
	VM_BUG_ON_PAGE(PageAnon(page), page);
	/*
	 * 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.
	 */
	mapping = page_rmapping(page);
	unlock_page(page);

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

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

2110 2111 2112 2113 2114 2115 2116 2117
/*
 * 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.
 */
2118
static inline void wp_page_reuse(struct vm_fault *vmf)
J
Jan Kara 已提交
2119
	__releases(vmf->ptl)
2120
{
J
Jan Kara 已提交
2121
	struct vm_area_struct *vma = vmf->vma;
J
Jan Kara 已提交
2122
	struct page *page = vmf->page;
2123 2124 2125 2126 2127 2128 2129 2130 2131
	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
2132 2133
	flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
	entry = pte_mkyoung(vmf->orig_pte);
2134
	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
J
Jan Kara 已提交
2135 2136 2137
	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);
2138 2139
}

2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155
/*
 * 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
2156
static int wp_page_copy(struct vm_fault *vmf)
2157
{
J
Jan Kara 已提交
2158
	struct vm_area_struct *vma = vmf->vma;
K
Kirill A. Shutemov 已提交
2159
	struct mm_struct *mm = vma->vm_mm;
J
Jan Kara 已提交
2160
	struct page *old_page = vmf->page;
2161 2162 2163
	struct page *new_page = NULL;
	pte_t entry;
	int page_copied = 0;
J
Jan Kara 已提交
2164
	const unsigned long mmun_start = vmf->address & PAGE_MASK;
K
Kirill A. Shutemov 已提交
2165
	const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2166 2167 2168 2169 2170
	struct mem_cgroup *memcg;

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

J
Jan Kara 已提交
2171
	if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
J
Jan Kara 已提交
2172 2173
		new_page = alloc_zeroed_user_highpage_movable(vma,
							      vmf->address);
2174 2175 2176
		if (!new_page)
			goto oom;
	} else {
K
Kirill A. Shutemov 已提交
2177
		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
J
Jan Kara 已提交
2178
				vmf->address);
2179 2180
		if (!new_page)
			goto oom;
J
Jan Kara 已提交
2181
		cow_user_page(new_page, old_page, vmf->address, vma);
2182 2183
	}

2184
	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2185 2186
		goto oom_free_new;

2187 2188
	__SetPageUptodate(new_page);

2189 2190 2191 2192 2193
	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);

	/*
	 * Re-check the pte - we dropped the lock
	 */
J
Jan Kara 已提交
2194
	vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
J
Jan Kara 已提交
2195
	if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2196 2197
		if (old_page) {
			if (!PageAnon(old_page)) {
2198 2199
				dec_mm_counter_fast(mm,
						mm_counter_file(old_page));
2200 2201 2202 2203 2204
				inc_mm_counter_fast(mm, MM_ANONPAGES);
			}
		} else {
			inc_mm_counter_fast(mm, MM_ANONPAGES);
		}
J
Jan Kara 已提交
2205
		flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2206 2207 2208 2209 2210 2211 2212 2213
		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
2214 2215
		ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
		page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2216
		mem_cgroup_commit_charge(new_page, memcg, false, false);
2217 2218 2219 2220 2221 2222
		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
2223 2224
		set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
		update_mmu_cache(vma, vmf->address, vmf->pte);
2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247
		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.
			 */
2248
			page_remove_rmap(old_page, false);
2249 2250 2251 2252 2253 2254
		}

		/* Free the old page.. */
		new_page = old_page;
		page_copied = 1;
	} else {
2255
		mem_cgroup_cancel_charge(new_page, memcg, false);
2256 2257 2258
	}

	if (new_page)
2259
		put_page(new_page);
2260

J
Jan Kara 已提交
2261
	pte_unmap_unlock(vmf->pte, vmf->ptl);
2262 2263 2264 2265 2266 2267 2268 2269
	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 */
2270 2271
			if (PageMlocked(old_page))
				munlock_vma_page(old_page);
2272 2273
			unlock_page(old_page);
		}
2274
		put_page(old_page);
2275 2276 2277
	}
	return page_copied ? VM_FAULT_WRITE : 0;
oom_free_new:
2278
	put_page(new_page);
2279 2280
oom:
	if (old_page)
2281
		put_page(old_page);
2282 2283 2284
	return VM_FAULT_OOM;
}

2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310
/**
 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
 *			  writeable once the page is prepared
 *
 * @vmf: structure describing the fault
 *
 * This function handles all that is needed to finish a write page fault in a
 * shared mapping due to PTE being read-only once the mapped page is prepared.
 * It handles locking of PTE and modifying it. The function returns
 * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
 * lock.
 *
 * The function expects the page to be locked or other protection against
 * concurrent faults / writeback (such as DAX radix tree locks).
 */
int finish_mkwrite_fault(struct vm_fault *vmf)
{
	WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
	vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
				       &vmf->ptl);
	/*
	 * We might have raced with another page fault while we released the
	 * pte_offset_map_lock.
	 */
	if (!pte_same(*vmf->pte, vmf->orig_pte)) {
		pte_unmap_unlock(vmf->pte, vmf->ptl);
2311
		return VM_FAULT_NOPAGE;
2312 2313
	}
	wp_page_reuse(vmf);
2314
	return 0;
2315 2316
}

2317 2318 2319 2320
/*
 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
 * mapping
 */
J
Jan Kara 已提交
2321
static int wp_pfn_shared(struct vm_fault *vmf)
2322
{
J
Jan Kara 已提交
2323
	struct vm_area_struct *vma = vmf->vma;
K
Kirill A. Shutemov 已提交
2324

2325 2326 2327
	if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
		int ret;

J
Jan Kara 已提交
2328
		pte_unmap_unlock(vmf->pte, vmf->ptl);
2329
		vmf->flags |= FAULT_FLAG_MKWRITE;
2330
		ret = vma->vm_ops->pfn_mkwrite(vmf);
2331
		if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2332
			return ret;
2333
		return finish_mkwrite_fault(vmf);
2334
	}
2335 2336
	wp_page_reuse(vmf);
	return VM_FAULT_WRITE;
2337 2338
}

J
Jan Kara 已提交
2339
static int wp_page_shared(struct vm_fault *vmf)
J
Jan Kara 已提交
2340
	__releases(vmf->ptl)
2341
{
J
Jan Kara 已提交
2342
	struct vm_area_struct *vma = vmf->vma;
2343

J
Jan Kara 已提交
2344
	get_page(vmf->page);
2345 2346 2347 2348

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

J
Jan Kara 已提交
2349
		pte_unmap_unlock(vmf->pte, vmf->ptl);
2350
		tmp = do_page_mkwrite(vmf);
2351 2352
		if (unlikely(!tmp || (tmp &
				      (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
J
Jan Kara 已提交
2353
			put_page(vmf->page);
2354 2355
			return tmp;
		}
2356
		tmp = finish_mkwrite_fault(vmf);
2357
		if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
J
Jan Kara 已提交
2358 2359
			unlock_page(vmf->page);
			put_page(vmf->page);
2360
			return tmp;
2361
		}
2362 2363
	} else {
		wp_page_reuse(vmf);
2364
		lock_page(vmf->page);
2365
	}
2366 2367
	fault_dirty_shared_page(vma, vmf->page);
	put_page(vmf->page);
2368

2369
	return VM_FAULT_WRITE;
2370 2371
}

L
Linus Torvalds 已提交
2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385
/*
 * 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.
 *
2386 2387 2388
 * 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
2389
 */
J
Jan Kara 已提交
2390
static int do_wp_page(struct vm_fault *vmf)
J
Jan Kara 已提交
2391
	__releases(vmf->ptl)
L
Linus Torvalds 已提交
2392
{
J
Jan Kara 已提交
2393
	struct vm_area_struct *vma = vmf->vma;
L
Linus Torvalds 已提交
2394

J
Jan Kara 已提交
2395 2396
	vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
	if (!vmf->page) {
2397
		/*
2398 2399
		 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
		 * VM_PFNMAP VMA.
2400 2401
		 *
		 * We should not cow pages in a shared writeable mapping.
2402
		 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2403 2404 2405
		 */
		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
				     (VM_WRITE|VM_SHARED))
J
Jan Kara 已提交
2406
			return wp_pfn_shared(vmf);
2407

J
Jan Kara 已提交
2408
		pte_unmap_unlock(vmf->pte, vmf->ptl);
J
Jan Kara 已提交
2409
		return wp_page_copy(vmf);
2410
	}
L
Linus Torvalds 已提交
2411

2412
	/*
P
Peter Zijlstra 已提交
2413 2414
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2415
	 */
J
Jan Kara 已提交
2416
	if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2417
		int total_mapcount;
J
Jan Kara 已提交
2418 2419
		if (!trylock_page(vmf->page)) {
			get_page(vmf->page);
J
Jan Kara 已提交
2420
			pte_unmap_unlock(vmf->pte, vmf->ptl);
J
Jan Kara 已提交
2421
			lock_page(vmf->page);
J
Jan Kara 已提交
2422 2423
			vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
					vmf->address, &vmf->ptl);
J
Jan Kara 已提交
2424
			if (!pte_same(*vmf->pte, vmf->orig_pte)) {
J
Jan Kara 已提交
2425
				unlock_page(vmf->page);
J
Jan Kara 已提交
2426
				pte_unmap_unlock(vmf->pte, vmf->ptl);
J
Jan Kara 已提交
2427
				put_page(vmf->page);
2428
				return 0;
2429
			}
J
Jan Kara 已提交
2430
			put_page(vmf->page);
P
Peter Zijlstra 已提交
2431
		}
J
Jan Kara 已提交
2432
		if (reuse_swap_page(vmf->page, &total_mapcount)) {
2433 2434 2435 2436 2437 2438 2439 2440
			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.
				 */
J
Jan Kara 已提交
2441
				page_move_anon_rmap(vmf->page, vma);
2442
			}
J
Jan Kara 已提交
2443
			unlock_page(vmf->page);
2444 2445
			wp_page_reuse(vmf);
			return VM_FAULT_WRITE;
2446
		}
J
Jan Kara 已提交
2447
		unlock_page(vmf->page);
P
Peter Zijlstra 已提交
2448
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2449
					(VM_WRITE|VM_SHARED))) {
J
Jan Kara 已提交
2450
		return wp_page_shared(vmf);
L
Linus Torvalds 已提交
2451 2452 2453 2454 2455
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
J
Jan Kara 已提交
2456
	get_page(vmf->page);
2457

J
Jan Kara 已提交
2458
	pte_unmap_unlock(vmf->pte, vmf->ptl);
J
Jan Kara 已提交
2459
	return wp_page_copy(vmf);
L
Linus Torvalds 已提交
2460 2461
}

2462
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
L
Linus Torvalds 已提交
2463 2464 2465
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
2466
	zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
L
Linus Torvalds 已提交
2467 2468
}

2469
static inline void unmap_mapping_range_tree(struct rb_root *root,
L
Linus Torvalds 已提交
2470 2471 2472 2473 2474
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	pgoff_t vba, vea, zba, zea;

2475
	vma_interval_tree_foreach(vma, root,
L
Linus Torvalds 已提交
2476 2477 2478
			details->first_index, details->last_index) {

		vba = vma->vm_pgoff;
2479
		vea = vba + vma_pages(vma) - 1;
L
Linus Torvalds 已提交
2480 2481 2482 2483 2484 2485 2486
		zba = details->first_index;
		if (zba < vba)
			zba = vba;
		zea = details->last_index;
		if (zea > vea)
			zea = vea;

2487
		unmap_mapping_range_vma(vma,
L
Linus Torvalds 已提交
2488 2489
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2490
				details);
L
Linus Torvalds 已提交
2491 2492 2493 2494
	}
}

/**
2495 2496 2497 2498
 * 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
2499
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2500 2501
 * @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
2502
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513
 * 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
2514
	struct zap_details details = { };
L
Linus Torvalds 已提交
2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525
	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;
	}

T
Tobin C Harding 已提交
2526
	details.check_mapping = even_cows ? NULL : mapping;
L
Linus Torvalds 已提交
2527 2528 2529 2530 2531
	details.first_index = hba;
	details.last_index = hba + hlen - 1;
	if (details.last_index < details.first_index)
		details.last_index = ULONG_MAX;

2532
	i_mmap_lock_write(mapping);
2533
	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
L
Linus Torvalds 已提交
2534
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
2535
	i_mmap_unlock_write(mapping);
L
Linus Torvalds 已提交
2536 2537 2538 2539
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
2540 2541
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
2542 2543 2544 2545
 * 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
2546
 */
J
Jan Kara 已提交
2547
int do_swap_page(struct vm_fault *vmf)
L
Linus Torvalds 已提交
2548
{
J
Jan Kara 已提交
2549
	struct vm_area_struct *vma = vmf->vma;
2550
	struct page *page, *swapcache;
2551
	struct mem_cgroup *memcg;
2552
	swp_entry_t entry;
L
Linus Torvalds 已提交
2553
	pte_t pte;
2554
	int locked;
2555
	int exclusive = 0;
N
Nick Piggin 已提交
2556
	int ret = 0;
L
Linus Torvalds 已提交
2557

J
Jan Kara 已提交
2558
	if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2559
		goto out;
2560

J
Jan Kara 已提交
2561
	entry = pte_to_swp_entry(vmf->orig_pte);
2562 2563
	if (unlikely(non_swap_entry(entry))) {
		if (is_migration_entry(entry)) {
J
Jan Kara 已提交
2564 2565
			migration_entry_wait(vma->vm_mm, vmf->pmd,
					     vmf->address);
2566 2567 2568
		} else if (is_hwpoison_entry(entry)) {
			ret = VM_FAULT_HWPOISON;
		} else {
J
Jan Kara 已提交
2569
			print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
H
Hugh Dickins 已提交
2570
			ret = VM_FAULT_SIGBUS;
2571
		}
2572 2573
		goto out;
	}
2574
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2575 2576
	page = lookup_swap_cache(entry);
	if (!page) {
J
Jan Kara 已提交
2577 2578
		page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, vma,
					vmf->address);
L
Linus Torvalds 已提交
2579 2580
		if (!page) {
			/*
2581 2582
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2583
			 */
J
Jan Kara 已提交
2584 2585
			vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
					vmf->address, &vmf->ptl);
J
Jan Kara 已提交
2586
			if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
L
Linus Torvalds 已提交
2587
				ret = VM_FAULT_OOM;
2588
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2589
			goto unlock;
L
Linus Torvalds 已提交
2590 2591 2592 2593
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2594
		count_vm_event(PGMAJFAULT);
K
Kirill A. Shutemov 已提交
2595
		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
2596
	} else if (PageHWPoison(page)) {
2597 2598 2599 2600
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2601 2602
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2603
		swapcache = page;
2604
		goto out_release;
L
Linus Torvalds 已提交
2605 2606
	}

2607
	swapcache = page;
J
Jan Kara 已提交
2608
	locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
R
Rik van Riel 已提交
2609

2610
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2611 2612 2613 2614
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2615

A
Andrea Arcangeli 已提交
2616
	/*
2617 2618 2619 2620
	 * 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
2621
	 */
2622
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2623 2624
		goto out_page;

J
Jan Kara 已提交
2625
	page = ksm_might_need_to_copy(page, vma, vmf->address);
2626 2627 2628 2629
	if (unlikely(!page)) {
		ret = VM_FAULT_OOM;
		page = swapcache;
		goto out_page;
H
Hugh Dickins 已提交
2630 2631
	}

K
Kirill A. Shutemov 已提交
2632 2633
	if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
				&memcg, false)) {
2634
		ret = VM_FAULT_OOM;
2635
		goto out_page;
2636 2637
	}

L
Linus Torvalds 已提交
2638
	/*
2639
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2640
	 */
J
Jan Kara 已提交
2641 2642
	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
			&vmf->ptl);
J
Jan Kara 已提交
2643
	if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2644 2645 2646 2647 2648
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2649 2650
	}

2651 2652 2653 2654 2655 2656 2657 2658 2659
	/*
	 * 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
2660

K
Kirill A. Shutemov 已提交
2661 2662
	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
	dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
2663
	pte = mk_pte(page, vma->vm_page_prot);
J
Jan Kara 已提交
2664
	if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
L
Linus Torvalds 已提交
2665
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
J
Jan Kara 已提交
2666
		vmf->flags &= ~FAULT_FLAG_WRITE;
2667
		ret |= VM_FAULT_WRITE;
2668
		exclusive = RMAP_EXCLUSIVE;
L
Linus Torvalds 已提交
2669 2670
	}
	flush_icache_page(vma, page);
J
Jan Kara 已提交
2671
	if (pte_swp_soft_dirty(vmf->orig_pte))
2672
		pte = pte_mksoft_dirty(pte);
J
Jan Kara 已提交
2673
	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
J
Jan Kara 已提交
2674
	vmf->orig_pte = pte;
2675
	if (page == swapcache) {
J
Jan Kara 已提交
2676
		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
2677
		mem_cgroup_commit_charge(page, memcg, true, false);
2678
		activate_page(page);
2679
	} else { /* ksm created a completely new copy */
J
Jan Kara 已提交
2680
		page_add_new_anon_rmap(page, vma, vmf->address, false);
2681
		mem_cgroup_commit_charge(page, memcg, false, false);
2682 2683
		lru_cache_add_active_or_unevictable(page, vma);
	}
L
Linus Torvalds 已提交
2684

2685
	swap_free(entry);
2686 2687
	if (mem_cgroup_swap_full(page) ||
	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2688
		try_to_free_swap(page);
2689
	unlock_page(page);
2690
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2691 2692 2693 2694 2695 2696 2697 2698 2699
		/*
		 * 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);
2700
		put_page(swapcache);
A
Andrea Arcangeli 已提交
2701
	}
2702

J
Jan Kara 已提交
2703
	if (vmf->flags & FAULT_FLAG_WRITE) {
J
Jan Kara 已提交
2704
		ret |= do_wp_page(vmf);
2705 2706
		if (ret & VM_FAULT_ERROR)
			ret &= VM_FAULT_ERROR;
L
Linus Torvalds 已提交
2707 2708 2709 2710
		goto out;
	}

	/* No need to invalidate - it was non-present before */
J
Jan Kara 已提交
2711
	update_mmu_cache(vma, vmf->address, vmf->pte);
2712
unlock:
J
Jan Kara 已提交
2713
	pte_unmap_unlock(vmf->pte, vmf->ptl);
L
Linus Torvalds 已提交
2714 2715
out:
	return ret;
2716
out_nomap:
2717
	mem_cgroup_cancel_charge(page, memcg, false);
J
Jan Kara 已提交
2718
	pte_unmap_unlock(vmf->pte, vmf->ptl);
2719
out_page:
2720
	unlock_page(page);
2721
out_release:
2722
	put_page(page);
2723
	if (page != swapcache) {
A
Andrea Arcangeli 已提交
2724
		unlock_page(swapcache);
2725
		put_page(swapcache);
A
Andrea Arcangeli 已提交
2726
	}
2727
	return ret;
L
Linus Torvalds 已提交
2728 2729
}

2730
/*
2731 2732
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2733 2734 2735 2736 2737 2738
 * 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) {
2739 2740 2741 2742 2743 2744 2745 2746 2747 2748
		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;
2749

2750
		return expand_downwards(vma, address - PAGE_SIZE);
2751
	}
2752 2753 2754 2755 2756 2757 2758
	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;

2759
		return expand_upwards(vma, address + PAGE_SIZE);
2760
	}
2761 2762 2763
	return 0;
}

L
Linus Torvalds 已提交
2764
/*
2765 2766 2767
 * 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
2768
 */
J
Jan Kara 已提交
2769
static int do_anonymous_page(struct vm_fault *vmf)
L
Linus Torvalds 已提交
2770
{
J
Jan Kara 已提交
2771
	struct vm_area_struct *vma = vmf->vma;
2772
	struct mem_cgroup *memcg;
2773
	struct page *page;
L
Linus Torvalds 已提交
2774 2775
	pte_t entry;

2776 2777 2778 2779
	/* File mapping without ->vm_ops ? */
	if (vma->vm_flags & VM_SHARED)
		return VM_FAULT_SIGBUS;

2780
	/* Check if we need to add a guard page to the stack */
J
Jan Kara 已提交
2781
	if (check_stack_guard_page(vma, vmf->address) < 0)
2782
		return VM_FAULT_SIGSEGV;
2783

2784 2785 2786 2787 2788 2789 2790 2791 2792 2793
	/*
	 * 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
2794
	if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
2795 2796 2797
		return VM_FAULT_OOM;

	/* See the comment in pte_alloc_one_map() */
J
Jan Kara 已提交
2798
	if (unlikely(pmd_trans_unstable(vmf->pmd)))
2799 2800
		return 0;

2801
	/* Use the zero-page for reads */
J
Jan Kara 已提交
2802
	if (!(vmf->flags & FAULT_FLAG_WRITE) &&
K
Kirill A. Shutemov 已提交
2803
			!mm_forbids_zeropage(vma->vm_mm)) {
J
Jan Kara 已提交
2804
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
H
Hugh Dickins 已提交
2805
						vma->vm_page_prot));
J
Jan Kara 已提交
2806 2807 2808
		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
2809
			goto unlock;
2810 2811
		/* Deliver the page fault to userland, check inside PT lock */
		if (userfaultfd_missing(vma)) {
J
Jan Kara 已提交
2812 2813
			pte_unmap_unlock(vmf->pte, vmf->ptl);
			return handle_userfault(vmf, VM_UFFD_MISSING);
2814
		}
H
Hugh Dickins 已提交
2815 2816 2817
		goto setpte;
	}

N
Nick Piggin 已提交
2818 2819 2820
	/* Allocate our own private page. */
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
J
Jan Kara 已提交
2821
	page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
N
Nick Piggin 已提交
2822 2823
	if (!page)
		goto oom;
2824

K
Kirill A. Shutemov 已提交
2825
	if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
2826 2827
		goto oom_free_page;

2828 2829 2830 2831 2832
	/*
	 * 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
2833
	__SetPageUptodate(page);
2834

N
Nick Piggin 已提交
2835
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
2836 2837
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
2838

J
Jan Kara 已提交
2839 2840 2841
	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
2842
		goto release;
H
Hugh Dickins 已提交
2843

2844 2845
	/* Deliver the page fault to userland, check inside PT lock */
	if (userfaultfd_missing(vma)) {
J
Jan Kara 已提交
2846
		pte_unmap_unlock(vmf->pte, vmf->ptl);
2847
		mem_cgroup_cancel_charge(page, memcg, false);
2848
		put_page(page);
J
Jan Kara 已提交
2849
		return handle_userfault(vmf, VM_UFFD_MISSING);
2850 2851
	}

K
Kirill A. Shutemov 已提交
2852
	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
J
Jan Kara 已提交
2853
	page_add_new_anon_rmap(page, vma, vmf->address, false);
2854
	mem_cgroup_commit_charge(page, memcg, false, false);
2855
	lru_cache_add_active_or_unevictable(page, vma);
H
Hugh Dickins 已提交
2856
setpte:
J
Jan Kara 已提交
2857
	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
L
Linus Torvalds 已提交
2858 2859

	/* No need to invalidate - it was non-present before */
J
Jan Kara 已提交
2860
	update_mmu_cache(vma, vmf->address, vmf->pte);
2861
unlock:
J
Jan Kara 已提交
2862
	pte_unmap_unlock(vmf->pte, vmf->ptl);
N
Nick Piggin 已提交
2863
	return 0;
2864
release:
2865
	mem_cgroup_cancel_charge(page, memcg, false);
2866
	put_page(page);
2867
	goto unlock;
2868
oom_free_page:
2869
	put_page(page);
2870
oom:
L
Linus Torvalds 已提交
2871 2872 2873
	return VM_FAULT_OOM;
}

2874 2875 2876 2877 2878
/*
 * 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
2879
static int __do_fault(struct vm_fault *vmf)
2880
{
J
Jan Kara 已提交
2881
	struct vm_area_struct *vma = vmf->vma;
2882 2883
	int ret;

2884
	ret = vma->vm_ops->fault(vmf);
2885
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
2886
			    VM_FAULT_DONE_COW)))
2887
		return ret;
2888

2889
	if (unlikely(PageHWPoison(vmf->page))) {
2890
		if (ret & VM_FAULT_LOCKED)
2891 2892
			unlock_page(vmf->page);
		put_page(vmf->page);
J
Jan Kara 已提交
2893
		vmf->page = NULL;
2894 2895 2896 2897
		return VM_FAULT_HWPOISON;
	}

	if (unlikely(!(ret & VM_FAULT_LOCKED)))
2898
		lock_page(vmf->page);
2899
	else
2900
		VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
2901 2902 2903 2904

	return ret;
}

J
Jan Kara 已提交
2905
static int pte_alloc_one_map(struct vm_fault *vmf)
2906
{
J
Jan Kara 已提交
2907
	struct vm_area_struct *vma = vmf->vma;
2908

J
Jan Kara 已提交
2909
	if (!pmd_none(*vmf->pmd))
2910
		goto map_pte;
J
Jan Kara 已提交
2911 2912 2913 2914
	if (vmf->prealloc_pte) {
		vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
		if (unlikely(!pmd_none(*vmf->pmd))) {
			spin_unlock(vmf->ptl);
2915 2916 2917 2918
			goto map_pte;
		}

		atomic_long_inc(&vma->vm_mm->nr_ptes);
J
Jan Kara 已提交
2919 2920
		pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
		spin_unlock(vmf->ptl);
2921
		vmf->prealloc_pte = NULL;
J
Jan Kara 已提交
2922
	} else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936
		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
2937
	if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd))
2938 2939
		return VM_FAULT_NOPAGE;

J
Jan Kara 已提交
2940 2941
	vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
			&vmf->ptl);
2942 2943 2944
	return 0;
}

2945
#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
K
Kirill A. Shutemov 已提交
2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958

#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
2959
static void deposit_prealloc_pte(struct vm_fault *vmf)
2960
{
J
Jan Kara 已提交
2961
	struct vm_area_struct *vma = vmf->vma;
2962

J
Jan Kara 已提交
2963
	pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
2964 2965 2966 2967 2968
	/*
	 * We are going to consume the prealloc table,
	 * count that as nr_ptes.
	 */
	atomic_long_inc(&vma->vm_mm->nr_ptes);
2969
	vmf->prealloc_pte = NULL;
2970 2971
}

J
Jan Kara 已提交
2972
static int do_set_pmd(struct vm_fault *vmf, struct page *page)
K
Kirill A. Shutemov 已提交
2973
{
J
Jan Kara 已提交
2974 2975 2976
	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
2977 2978 2979 2980 2981 2982 2983 2984 2985
	pmd_t entry;
	int i, ret;

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

	ret = VM_FAULT_FALLBACK;
	page = compound_head(page);

2986 2987 2988 2989
	/*
	 * 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
2990 2991 2992
	if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
		vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
		if (!vmf->prealloc_pte)
2993 2994 2995 2996
			return VM_FAULT_OOM;
		smp_wmb(); /* See comment in __pte_alloc() */
	}

J
Jan Kara 已提交
2997 2998
	vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
	if (unlikely(!pmd_none(*vmf->pmd)))
K
Kirill A. Shutemov 已提交
2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009
		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);
3010 3011 3012 3013
	/*
	 * deposit and withdraw with pmd lock held
	 */
	if (arch_needs_pgtable_deposit())
J
Jan Kara 已提交
3014
		deposit_prealloc_pte(vmf);
K
Kirill A. Shutemov 已提交
3015

J
Jan Kara 已提交
3016
	set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
K
Kirill A. Shutemov 已提交
3017

J
Jan Kara 已提交
3018
	update_mmu_cache_pmd(vma, haddr, vmf->pmd);
K
Kirill A. Shutemov 已提交
3019 3020 3021

	/* fault is handled */
	ret = 0;
3022
	count_vm_event(THP_FILE_MAPPED);
K
Kirill A. Shutemov 已提交
3023
out:
J
Jan Kara 已提交
3024
	spin_unlock(vmf->ptl);
K
Kirill A. Shutemov 已提交
3025 3026 3027
	return ret;
}
#else
J
Jan Kara 已提交
3028
static int do_set_pmd(struct vm_fault *vmf, struct page *page)
K
Kirill A. Shutemov 已提交
3029 3030 3031 3032 3033 3034
{
	BUILD_BUG();
	return 0;
}
#endif

3035
/**
3036 3037
 * 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.
3038
 *
J
Jan Kara 已提交
3039
 * @vmf: fault environment
3040
 * @memcg: memcg to charge page (only for private mappings)
3041 3042
 * @page: page to map
 *
J
Jan Kara 已提交
3043 3044
 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
 * return.
3045 3046 3047 3048
 *
 * Target users are page handler itself and implementations of
 * vm_ops->map_pages.
 */
J
Jan Kara 已提交
3049
int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3050
		struct page *page)
3051
{
J
Jan Kara 已提交
3052 3053
	struct vm_area_struct *vma = vmf->vma;
	bool write = vmf->flags & FAULT_FLAG_WRITE;
3054
	pte_t entry;
K
Kirill A. Shutemov 已提交
3055 3056
	int ret;

J
Jan Kara 已提交
3057
	if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3058
			IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
K
Kirill A. Shutemov 已提交
3059 3060 3061
		/* THP on COW? */
		VM_BUG_ON_PAGE(memcg, page);

J
Jan Kara 已提交
3062
		ret = do_set_pmd(vmf, page);
K
Kirill A. Shutemov 已提交
3063
		if (ret != VM_FAULT_FALLBACK)
H
Hugh Dickins 已提交
3064
			return ret;
K
Kirill A. Shutemov 已提交
3065
	}
3066

J
Jan Kara 已提交
3067 3068
	if (!vmf->pte) {
		ret = pte_alloc_one_map(vmf);
3069
		if (ret)
H
Hugh Dickins 已提交
3070
			return ret;
3071 3072 3073
	}

	/* Re-check under ptl */
H
Hugh Dickins 已提交
3074 3075
	if (unlikely(!pte_none(*vmf->pte)))
		return VM_FAULT_NOPAGE;
3076

3077 3078 3079 3080
	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
3081 3082
	/* copy-on-write page */
	if (write && !(vma->vm_flags & VM_SHARED)) {
3083
		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
J
Jan Kara 已提交
3084
		page_add_new_anon_rmap(page, vma, vmf->address, false);
3085 3086
		mem_cgroup_commit_charge(page, memcg, false, false);
		lru_cache_add_active_or_unevictable(page, vma);
3087
	} else {
3088
		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
K
Kirill A. Shutemov 已提交
3089
		page_add_file_rmap(page, false);
3090
	}
J
Jan Kara 已提交
3091
	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3092 3093

	/* no need to invalidate: a not-present page won't be cached */
J
Jan Kara 已提交
3094
	update_mmu_cache(vma, vmf->address, vmf->pte);
3095

H
Hugh Dickins 已提交
3096
	return 0;
3097 3098
}

3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130

/**
 * 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;
}

3131 3132
static unsigned long fault_around_bytes __read_mostly =
	rounddown_pow_of_two(65536);
3133 3134 3135

#ifdef CONFIG_DEBUG_FS
static int fault_around_bytes_get(void *data, u64 *val)
3136
{
3137
	*val = fault_around_bytes;
3138 3139 3140
	return 0;
}

3141 3142 3143 3144 3145
/*
 * 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.
 */
3146
static int fault_around_bytes_set(void *data, u64 val)
3147
{
3148
	if (val / PAGE_SIZE > PTRS_PER_PTE)
3149
		return -EINVAL;
3150 3151 3152 3153
	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 */
3154 3155
	return 0;
}
3156 3157
DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
		fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3158 3159 3160 3161 3162

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

3163 3164
	ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
			&fault_around_bytes_fops);
3165
	if (!ret)
3166
		pr_warn("Failed to create fault_around_bytes in debugfs");
3167 3168 3169 3170
	return 0;
}
late_initcall(fault_around_debugfs);
#endif
3171

3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194
/*
 * 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.
 */
3195
static int do_fault_around(struct vm_fault *vmf)
3196
{
J
Jan Kara 已提交
3197
	unsigned long address = vmf->address, nr_pages, mask;
3198
	pgoff_t start_pgoff = vmf->pgoff;
K
Kirill A. Shutemov 已提交
3199
	pgoff_t end_pgoff;
3200
	int off, ret = 0;
3201

3202
	nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3203 3204
	mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;

J
Jan Kara 已提交
3205 3206
	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
3207
	start_pgoff -= off;
3208 3209

	/*
K
Kirill A. Shutemov 已提交
3210 3211
	 *  end_pgoff is either end of page table or end of vma
	 *  or fault_around_pages() from start_pgoff, depending what is nearest.
3212
	 */
K
Kirill A. Shutemov 已提交
3213
	end_pgoff = start_pgoff -
J
Jan Kara 已提交
3214
		((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3215
		PTRS_PER_PTE - 1;
J
Jan Kara 已提交
3216
	end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
K
Kirill A. Shutemov 已提交
3217
			start_pgoff + nr_pages - 1);
3218

J
Jan Kara 已提交
3219 3220 3221 3222
	if (pmd_none(*vmf->pmd)) {
		vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
						  vmf->address);
		if (!vmf->prealloc_pte)
3223
			goto out;
3224
		smp_wmb(); /* See comment in __pte_alloc() */
3225 3226
	}

J
Jan Kara 已提交
3227
	vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3228 3229

	/* Huge page is mapped? Page fault is solved */
J
Jan Kara 已提交
3230
	if (pmd_trans_huge(*vmf->pmd)) {
3231 3232 3233 3234 3235
		ret = VM_FAULT_NOPAGE;
		goto out;
	}

	/* ->map_pages() haven't done anything useful. Cold page cache? */
J
Jan Kara 已提交
3236
	if (!vmf->pte)
3237 3238 3239
		goto out;

	/* check if the page fault is solved */
J
Jan Kara 已提交
3240 3241
	vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
	if (!pte_none(*vmf->pte))
3242
		ret = VM_FAULT_NOPAGE;
J
Jan Kara 已提交
3243
	pte_unmap_unlock(vmf->pte, vmf->ptl);
K
Kirill A. Shutemov 已提交
3244
out:
J
Jan Kara 已提交
3245 3246
	vmf->address = address;
	vmf->pte = NULL;
3247
	return ret;
3248 3249
}

3250
static int do_read_fault(struct vm_fault *vmf)
3251
{
J
Jan Kara 已提交
3252
	struct vm_area_struct *vma = vmf->vma;
3253 3254 3255 3256 3257 3258 3259
	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).
	 */
3260
	if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3261
		ret = do_fault_around(vmf);
3262 3263
		if (ret)
			return ret;
3264
	}
3265

J
Jan Kara 已提交
3266
	ret = __do_fault(vmf);
3267 3268 3269
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		return ret;

3270
	ret |= finish_fault(vmf);
J
Jan Kara 已提交
3271
	unlock_page(vmf->page);
3272
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
J
Jan Kara 已提交
3273
		put_page(vmf->page);
3274 3275 3276
	return ret;
}

3277
static int do_cow_fault(struct vm_fault *vmf)
3278
{
J
Jan Kara 已提交
3279
	struct vm_area_struct *vma = vmf->vma;
3280 3281 3282 3283 3284
	int ret;

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

J
Jan Kara 已提交
3285 3286
	vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
	if (!vmf->cow_page)
3287 3288
		return VM_FAULT_OOM;

J
Jan Kara 已提交
3289
	if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3290
				&vmf->memcg, false)) {
J
Jan Kara 已提交
3291
		put_page(vmf->cow_page);
3292 3293 3294
		return VM_FAULT_OOM;
	}

J
Jan Kara 已提交
3295
	ret = __do_fault(vmf);
3296 3297
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		goto uncharge_out;
3298 3299
	if (ret & VM_FAULT_DONE_COW)
		return ret;
3300

3301
	copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
J
Jan Kara 已提交
3302
	__SetPageUptodate(vmf->cow_page);
3303

3304
	ret |= finish_fault(vmf);
3305 3306
	unlock_page(vmf->page);
	put_page(vmf->page);
3307 3308
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
		goto uncharge_out;
3309 3310
	return ret;
uncharge_out:
3311
	mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
J
Jan Kara 已提交
3312
	put_page(vmf->cow_page);
3313 3314 3315
	return ret;
}

3316
static int do_shared_fault(struct vm_fault *vmf)
L
Linus Torvalds 已提交
3317
{
J
Jan Kara 已提交
3318
	struct vm_area_struct *vma = vmf->vma;
3319
	int ret, tmp;
3320

J
Jan Kara 已提交
3321
	ret = __do_fault(vmf);
3322
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3323
		return ret;
L
Linus Torvalds 已提交
3324 3325

	/*
3326 3327
	 * Check if the backing address space wants to know that the page is
	 * about to become writable
L
Linus Torvalds 已提交
3328
	 */
3329
	if (vma->vm_ops->page_mkwrite) {
J
Jan Kara 已提交
3330
		unlock_page(vmf->page);
3331
		tmp = do_page_mkwrite(vmf);
3332 3333
		if (unlikely(!tmp ||
				(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
J
Jan Kara 已提交
3334
			put_page(vmf->page);
3335
			return tmp;
3336
		}
3337 3338
	}

3339
	ret |= finish_fault(vmf);
3340 3341
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
					VM_FAULT_RETRY))) {
J
Jan Kara 已提交
3342 3343
		unlock_page(vmf->page);
		put_page(vmf->page);
3344
		return ret;
L
Linus Torvalds 已提交
3345
	}
N
Nick Piggin 已提交
3346

3347
	fault_dirty_shared_page(vma, vmf->page);
3348
	return ret;
3349
}
3350

3351 3352 3353 3354 3355 3356
/*
 * 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
3357
static int do_fault(struct vm_fault *vmf)
3358
{
J
Jan Kara 已提交
3359
	struct vm_area_struct *vma = vmf->vma;
H
Hugh Dickins 已提交
3360
	int ret;
3361

3362 3363
	/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
	if (!vma->vm_ops->fault)
H
Hugh Dickins 已提交
3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374
		ret = VM_FAULT_SIGBUS;
	else if (!(vmf->flags & FAULT_FLAG_WRITE))
		ret = do_read_fault(vmf);
	else if (!(vma->vm_flags & VM_SHARED))
		ret = do_cow_fault(vmf);
	else
		ret = do_shared_fault(vmf);

	/* preallocated pagetable is unused: free it */
	if (vmf->prealloc_pte) {
		pte_free(vma->vm_mm, vmf->prealloc_pte);
3375
		vmf->prealloc_pte = NULL;
H
Hugh Dickins 已提交
3376 3377
	}
	return ret;
3378 3379
}

3380
static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3381 3382
				unsigned long addr, int page_nid,
				int *flags)
3383 3384 3385 3386
{
	get_page(page);

	count_vm_numa_event(NUMA_HINT_FAULTS);
3387
	if (page_nid == numa_node_id()) {
3388
		count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3389 3390
		*flags |= TNF_FAULT_LOCAL;
	}
3391 3392 3393 3394

	return mpol_misplaced(page, vma, addr);
}

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

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

3419 3420 3421 3422 3423
	/*
	 * Make it present again, Depending on how arch implementes non
	 * accessible ptes, some can allow access by kernel mode.
	 */
	pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
3424 3425
	pte = pte_modify(pte, vma->vm_page_prot);
	pte = pte_mkyoung(pte);
3426 3427
	if (was_writable)
		pte = pte_mkwrite(pte);
3428
	ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
J
Jan Kara 已提交
3429
	update_mmu_cache(vma, vmf->address, vmf->pte);
3430

J
Jan Kara 已提交
3431
	page = vm_normal_page(vma, vmf->address, pte);
3432
	if (!page) {
J
Jan Kara 已提交
3433
		pte_unmap_unlock(vmf->pte, vmf->ptl);
3434 3435 3436
		return 0;
	}

3437 3438
	/* TODO: handle PTE-mapped THP */
	if (PageCompound(page)) {
J
Jan Kara 已提交
3439
		pte_unmap_unlock(vmf->pte, vmf->ptl);
3440 3441 3442
		return 0;
	}

3443
	/*
3444 3445 3446 3447 3448 3449
	 * 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.
3450
	 */
3451
	if (!pte_write(pte))
3452 3453
		flags |= TNF_NO_GROUP;

3454 3455 3456 3457 3458 3459 3460
	/*
	 * 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;

3461
	last_cpupid = page_cpupid_last(page);
3462
	page_nid = page_to_nid(page);
J
Jan Kara 已提交
3463
	target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
K
Kirill A. Shutemov 已提交
3464
			&flags);
J
Jan Kara 已提交
3465
	pte_unmap_unlock(vmf->pte, vmf->ptl);
3466 3467 3468 3469 3470 3471
	if (target_nid == -1) {
		put_page(page);
		goto out;
	}

	/* Migrate to the requested node */
3472
	migrated = migrate_misplaced_page(page, vma, target_nid);
3473
	if (migrated) {
3474
		page_nid = target_nid;
3475
		flags |= TNF_MIGRATED;
3476 3477
	} else
		flags |= TNF_MIGRATE_FAIL;
3478 3479

out:
3480
	if (page_nid != -1)
3481
		task_numa_fault(last_cpupid, page_nid, 1, flags);
3482 3483 3484
	return 0;
}

J
Jan Kara 已提交
3485
static int create_huge_pmd(struct vm_fault *vmf)
M
Matthew Wilcox 已提交
3486
{
3487
	if (vma_is_anonymous(vmf->vma))
J
Jan Kara 已提交
3488
		return do_huge_pmd_anonymous_page(vmf);
3489
	if (vmf->vma->vm_ops->huge_fault)
3490
		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
M
Matthew Wilcox 已提交
3491 3492 3493
	return VM_FAULT_FALLBACK;
}

J
Jan Kara 已提交
3494
static int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
M
Matthew Wilcox 已提交
3495
{
J
Jan Kara 已提交
3496 3497
	if (vma_is_anonymous(vmf->vma))
		return do_huge_pmd_wp_page(vmf, orig_pmd);
3498
	if (vmf->vma->vm_ops->huge_fault)
3499
		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
K
Kirill A. Shutemov 已提交
3500 3501

	/* COW handled on pte level: split pmd */
J
Jan Kara 已提交
3502 3503
	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
3504

M
Matthew Wilcox 已提交
3505 3506 3507
	return VM_FAULT_FALLBACK;
}

3508 3509 3510 3511 3512
static inline bool vma_is_accessible(struct vm_area_struct *vma)
{
	return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
}

3513 3514 3515 3516 3517 3518 3519
static int create_huge_pud(struct vm_fault *vmf)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
	/* No support for anonymous transparent PUD pages yet */
	if (vma_is_anonymous(vmf->vma))
		return VM_FAULT_FALLBACK;
	if (vmf->vma->vm_ops->huge_fault)
3520
		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3521 3522 3523 3524 3525 3526 3527 3528 3529 3530 3531
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
	return VM_FAULT_FALLBACK;
}

static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
	/* No support for anonymous transparent PUD pages yet */
	if (vma_is_anonymous(vmf->vma))
		return VM_FAULT_FALLBACK;
	if (vmf->vma->vm_ops->huge_fault)
3532
		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3533 3534 3535 3536
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
	return VM_FAULT_FALLBACK;
}

L
Linus Torvalds 已提交
3537 3538 3539 3540 3541 3542 3543 3544 3545
/*
 * 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).
 *
3546 3547
 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
 * concurrent faults).
3548
 *
3549 3550
 * 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
3551
 */
J
Jan Kara 已提交
3552
static int handle_pte_fault(struct vm_fault *vmf)
L
Linus Torvalds 已提交
3553 3554 3555
{
	pte_t entry;

J
Jan Kara 已提交
3556
	if (unlikely(pmd_none(*vmf->pmd))) {
3557 3558 3559 3560 3561 3562
		/*
		 * 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
3563
		vmf->pte = NULL;
3564 3565
	} else {
		/* See comment in pte_alloc_one_map() */
J
Jan Kara 已提交
3566
		if (pmd_trans_unstable(vmf->pmd) || pmd_devmap(*vmf->pmd))
3567 3568 3569 3570 3571 3572 3573
			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
3574
		vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
J
Jan Kara 已提交
3575
		vmf->orig_pte = *vmf->pte;
3576 3577 3578 3579 3580 3581 3582 3583 3584 3585

		/*
		 * 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
3586
		if (pte_none(vmf->orig_pte)) {
J
Jan Kara 已提交
3587 3588
			pte_unmap(vmf->pte);
			vmf->pte = NULL;
3589
		}
L
Linus Torvalds 已提交
3590 3591
	}

J
Jan Kara 已提交
3592 3593 3594
	if (!vmf->pte) {
		if (vma_is_anonymous(vmf->vma))
			return do_anonymous_page(vmf);
3595
		else
J
Jan Kara 已提交
3596
			return do_fault(vmf);
3597 3598
	}

J
Jan Kara 已提交
3599 3600
	if (!pte_present(vmf->orig_pte))
		return do_swap_page(vmf);
3601

J
Jan Kara 已提交
3602 3603
	if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
		return do_numa_page(vmf);
3604

J
Jan Kara 已提交
3605 3606
	vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
	spin_lock(vmf->ptl);
J
Jan Kara 已提交
3607
	entry = vmf->orig_pte;
J
Jan Kara 已提交
3608
	if (unlikely(!pte_same(*vmf->pte, entry)))
3609
		goto unlock;
J
Jan Kara 已提交
3610
	if (vmf->flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3611
		if (!pte_write(entry))
J
Jan Kara 已提交
3612
			return do_wp_page(vmf);
L
Linus Torvalds 已提交
3613 3614 3615
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
J
Jan Kara 已提交
3616 3617 3618
	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);
3619 3620 3621 3622 3623 3624 3625
	} 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
3626 3627
		if (vmf->flags & FAULT_FLAG_WRITE)
			flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3628
	}
3629
unlock:
J
Jan Kara 已提交
3630
	pte_unmap_unlock(vmf->pte, vmf->ptl);
N
Nick Piggin 已提交
3631
	return 0;
L
Linus Torvalds 已提交
3632 3633 3634 3635
}

/*
 * By the time we get here, we already hold the mm semaphore
3636 3637 3638
 *
 * 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
3639
 */
3640 3641
static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
		unsigned int flags)
L
Linus Torvalds 已提交
3642
{
J
Jan Kara 已提交
3643
	struct vm_fault vmf = {
K
Kirill A. Shutemov 已提交
3644
		.vma = vma,
3645
		.address = address & PAGE_MASK,
K
Kirill A. Shutemov 已提交
3646
		.flags = flags,
3647
		.pgoff = linear_page_index(vma, address),
3648
		.gfp_mask = __get_fault_gfp_mask(vma),
K
Kirill A. Shutemov 已提交
3649
	};
3650
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
3651
	pgd_t *pgd;
3652
	int ret;
L
Linus Torvalds 已提交
3653 3654

	pgd = pgd_offset(mm, address);
3655 3656 3657

	vmf.pud = pud_alloc(mm, pgd, address);
	if (!vmf.pud)
H
Hugh Dickins 已提交
3658
		return VM_FAULT_OOM;
3659 3660 3661 3662 3663 3664 3665 3666 3667 3668 3669 3670 3671 3672 3673 3674 3675 3676 3677 3678 3679 3680 3681 3682 3683
	if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) {
		ret = create_huge_pud(&vmf);
		if (!(ret & VM_FAULT_FALLBACK))
			return ret;
	} else {
		pud_t orig_pud = *vmf.pud;

		barrier();
		if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
			unsigned int dirty = flags & FAULT_FLAG_WRITE;

			/* NUMA case for anonymous PUDs would go here */

			if (dirty && !pud_write(orig_pud)) {
				ret = wp_huge_pud(&vmf, orig_pud);
				if (!(ret & VM_FAULT_FALLBACK))
					return ret;
			} else {
				huge_pud_set_accessed(&vmf, orig_pud);
				return 0;
			}
		}
	}

	vmf.pmd = pmd_alloc(mm, vmf.pud, address);
J
Jan Kara 已提交
3684
	if (!vmf.pmd)
H
Hugh Dickins 已提交
3685
		return VM_FAULT_OOM;
J
Jan Kara 已提交
3686
	if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
3687
		ret = create_huge_pmd(&vmf);
3688 3689
		if (!(ret & VM_FAULT_FALLBACK))
			return ret;
3690
	} else {
J
Jan Kara 已提交
3691
		pmd_t orig_pmd = *vmf.pmd;
3692

3693
		barrier();
3694
		if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3695
			if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
J
Jan Kara 已提交
3696
				return do_huge_pmd_numa_page(&vmf, orig_pmd);
3697

J
Jan Kara 已提交
3698
			if ((vmf.flags & FAULT_FLAG_WRITE) &&
K
Kirill A. Shutemov 已提交
3699
					!pmd_write(orig_pmd)) {
J
Jan Kara 已提交
3700
				ret = wp_huge_pmd(&vmf, orig_pmd);
3701 3702
				if (!(ret & VM_FAULT_FALLBACK))
					return ret;
3703
			} else {
J
Jan Kara 已提交
3704
				huge_pmd_set_accessed(&vmf, orig_pmd);
3705
				return 0;
3706
			}
3707 3708 3709
		}
	}

J
Jan Kara 已提交
3710
	return handle_pte_fault(&vmf);
L
Linus Torvalds 已提交
3711 3712
}

3713 3714 3715 3716 3717 3718
/*
 * 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().
 */
3719 3720
int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
		unsigned int flags)
3721 3722 3723 3724 3725 3726
{
	int ret;

	__set_current_state(TASK_RUNNING);

	count_vm_event(PGFAULT);
3727
	mem_cgroup_count_vm_event(vma->vm_mm, PGFAULT);
3728 3729 3730 3731 3732 3733 3734 3735 3736

	/* 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)
3737
		mem_cgroup_oom_enable();
3738

K
Kirill A. Shutemov 已提交
3739 3740 3741 3742 3743 3744 3745 3746 3747
	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);
3748

3749 3750
	if (flags & FAULT_FLAG_USER) {
		mem_cgroup_oom_disable();
T
Tobin C Harding 已提交
3751 3752 3753 3754 3755 3756 3757 3758
		/*
		 * 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);
3759
	}
3760

3761 3762 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773
	/*
	 * 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;

3774 3775
	return ret;
}
3776
EXPORT_SYMBOL_GPL(handle_mm_fault);
3777

L
Linus Torvalds 已提交
3778 3779 3780
#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3781
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3782
 */
3783
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3784
{
H
Hugh Dickins 已提交
3785 3786
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3787
		return -ENOMEM;
L
Linus Torvalds 已提交
3788

3789 3790
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3791
	spin_lock(&mm->page_table_lock);
3792
	if (pgd_present(*pgd))		/* Another has populated it */
3793
		pud_free(mm, new);
3794 3795
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3796
	spin_unlock(&mm->page_table_lock);
3797
	return 0;
L
Linus Torvalds 已提交
3798 3799 3800 3801 3802 3803
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3804
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3805
 */
3806
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3807
{
3808
	spinlock_t *ptl;
H
Hugh Dickins 已提交
3809 3810
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3811
		return -ENOMEM;
L
Linus Torvalds 已提交
3812

3813 3814
	smp_wmb(); /* See comment in __pte_alloc */

3815
	ptl = pud_lock(mm, pud);
L
Linus Torvalds 已提交
3816
#ifndef __ARCH_HAS_4LEVEL_HACK
3817 3818
	if (!pud_present(*pud)) {
		mm_inc_nr_pmds(mm);
3819
		pud_populate(mm, pud, new);
3820
	} else	/* Another has populated it */
3821
		pmd_free(mm, new);
3822 3823 3824
#else
	if (!pgd_present(*pud)) {
		mm_inc_nr_pmds(mm);
3825
		pgd_populate(mm, pud, new);
3826 3827
	} else /* Another has populated it */
		pmd_free(mm, new);
L
Linus Torvalds 已提交
3828
#endif /* __ARCH_HAS_4LEVEL_HACK */
3829
	spin_unlock(ptl);
3830
	return 0;
3831
}
L
Linus Torvalds 已提交
3832 3833
#endif /* __PAGETABLE_PMD_FOLDED */

R
Ross Zwisler 已提交
3834 3835
static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
		pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
J
Johannes Weiner 已提交
3836 3837 3838 3839 3840 3841 3842 3843 3844 3845 3846 3847 3848 3849 3850
{
	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);
3851
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3852

R
Ross Zwisler 已提交
3853 3854 3855 3856 3857 3858 3859 3860 3861 3862 3863 3864 3865
	if (pmd_huge(*pmd)) {
		if (!pmdpp)
			goto out;

		*ptlp = pmd_lock(mm, pmd);
		if (pmd_huge(*pmd)) {
			*pmdpp = pmd;
			return 0;
		}
		spin_unlock(*ptlp);
	}

	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
J
Johannes Weiner 已提交
3866 3867 3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880
		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;
}

3881 3882
static inline int follow_pte(struct mm_struct *mm, unsigned long address,
			     pte_t **ptepp, spinlock_t **ptlp)
3883 3884 3885 3886 3887
{
	int res;

	/* (void) is needed to make gcc happy */
	(void) __cond_lock(*ptlp,
R
Ross Zwisler 已提交
3888 3889 3890 3891 3892 3893 3894 3895 3896 3897 3898 3899 3900 3901
			   !(res = __follow_pte_pmd(mm, address, ptepp, NULL,
					   ptlp)));
	return res;
}

int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
			     pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
{
	int res;

	/* (void) is needed to make gcc happy */
	(void) __cond_lock(*ptlp,
			   !(res = __follow_pte_pmd(mm, address, ptepp, pmdpp,
					   ptlp)));
3902 3903
	return res;
}
R
Ross Zwisler 已提交
3904
EXPORT_SYMBOL(follow_pte_pmd);
3905

J
Johannes Weiner 已提交
3906 3907 3908 3909 3910 3911 3912 3913 3914 3915 3916 3917 3918 3919 3920 3921 3922 3923 3924 3925 3926 3927 3928 3929 3930 3931 3932 3933 3934
/**
 * 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);

3935
#ifdef CONFIG_HAVE_IOREMAP_PROT
3936 3937 3938
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3939
{
3940
	int ret = -EINVAL;
3941 3942 3943
	pte_t *ptep, pte;
	spinlock_t *ptl;

3944 3945
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3946

3947
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3948
		goto out;
3949
	pte = *ptep;
3950

3951 3952 3953 3954
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3955
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3956

3957
	ret = 0;
3958 3959 3960
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3961
	return ret;
3962 3963 3964 3965 3966 3967 3968
}

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
3969
	void __iomem *maddr;
3970 3971
	int offset = addr & (PAGE_SIZE-1);

3972
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3973 3974
		return -EINVAL;

3975
	maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
3976 3977 3978 3979 3980 3981 3982 3983
	if (write)
		memcpy_toio(maddr + offset, buf, len);
	else
		memcpy_fromio(buf, maddr + offset, len);
	iounmap(maddr);

	return len;
}
3984
EXPORT_SYMBOL_GPL(generic_access_phys);
3985 3986
#endif

3987
/*
3988 3989
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
3990
 */
3991
int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3992
		unsigned long addr, void *buf, int len, unsigned int gup_flags)
3993 3994 3995
{
	struct vm_area_struct *vma;
	void *old_buf = buf;
3996
	int write = gup_flags & FOLL_WRITE;
3997 3998

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3999
	/* ignore errors, just check how much was successfully transferred */
4000 4001 4002
	while (len) {
		int bytes, ret, offset;
		void *maddr;
4003
		struct page *page = NULL;
4004

4005
		ret = get_user_pages_remote(tsk, mm, addr, 1,
4006
				gup_flags, &page, &vma, NULL);
4007
		if (ret <= 0) {
4008 4009 4010
#ifndef CONFIG_HAVE_IOREMAP_PROT
			break;
#else
4011 4012 4013 4014 4015
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
			vma = find_vma(mm, addr);
4016
			if (!vma || vma->vm_start > addr)
4017 4018 4019 4020 4021 4022 4023
				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;
4024
#endif
4025
		} else {
4026 4027 4028 4029 4030 4031 4032 4033 4034 4035 4036 4037 4038 4039 4040
			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);
4041
			put_page(page);
4042 4043 4044 4045 4046 4047 4048 4049 4050
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
4051

S
Stephen Wilson 已提交
4052
/**
4053
 * access_remote_vm - access another process' address space
S
Stephen Wilson 已提交
4054 4055 4056 4057
 * @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
4058
 * @gup_flags:	flags modifying lookup behaviour
S
Stephen Wilson 已提交
4059 4060 4061 4062
 *
 * The caller must hold a reference on @mm.
 */
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4063
		void *buf, int len, unsigned int gup_flags)
S
Stephen Wilson 已提交
4064
{
4065
	return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
S
Stephen Wilson 已提交
4066 4067
}

4068 4069 4070 4071 4072 4073
/*
 * 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,
4074
		void *buf, int len, unsigned int gup_flags)
4075 4076 4077 4078 4079 4080 4081 4082
{
	struct mm_struct *mm;
	int ret;

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

4083
	ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4084

4085 4086 4087 4088
	mmput(mm);

	return ret;
}
4089
EXPORT_SYMBOL_GPL(access_process_vm);
4090

4091 4092 4093 4094 4095 4096 4097 4098
/*
 * 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;

4099 4100 4101 4102 4103 4104 4105
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

4106 4107 4108 4109 4110 4111
	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
4112
			char *p;
4113

M
Miklos Szeredi 已提交
4114
			p = file_path(f, buf, PAGE_SIZE);
4115 4116
			if (IS_ERR(p))
				p = "?";
A
Andy Shevchenko 已提交
4117
			printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4118 4119 4120 4121 4122
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
4123
	up_read(&mm->mmap_sem);
4124
}
4125

4126
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4127
void __might_fault(const char *file, int line)
4128
{
4129 4130 4131 4132 4133 4134 4135 4136
	/*
	 * 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;
4137
	if (pagefault_disabled())
4138
		return;
4139 4140
	__might_sleep(file, line, 0);
#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4141
	if (current->mm)
4142
		might_lock_read(&current->mm->mmap_sem);
4143
#endif
4144
}
4145
EXPORT_SYMBOL(__might_fault);
4146
#endif
A
Andrea Arcangeli 已提交
4147 4148 4149 4150 4151 4152 4153 4154 4155 4156 4157 4158 4159 4160 4161 4162 4163 4164 4165 4166 4167 4168 4169 4170 4171 4172 4173 4174 4175 4176 4177 4178 4179 4180 4181 4182 4183 4184 4185 4186 4187 4188 4189 4190 4191 4192 4193 4194 4195 4196 4197 4198 4199 4200 4201 4202 4203 4204 4205 4206 4207 4208 4209 4210 4211 4212 4213 4214 4215 4216

#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);
	}
}
4217 4218 4219

long copy_huge_page_from_user(struct page *dst_page,
				const void __user *usr_src,
4220 4221
				unsigned int pages_per_huge_page,
				bool allow_pagefault)
4222 4223 4224 4225 4226 4227 4228
{
	void *src = (void *)usr_src;
	void *page_kaddr;
	unsigned long i, rc = 0;
	unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;

	for (i = 0; i < pages_per_huge_page; i++) {
4229 4230 4231 4232
		if (allow_pagefault)
			page_kaddr = kmap(dst_page + i);
		else
			page_kaddr = kmap_atomic(dst_page + i);
4233 4234 4235
		rc = copy_from_user(page_kaddr,
				(const void __user *)(src + i * PAGE_SIZE),
				PAGE_SIZE);
4236 4237 4238 4239
		if (allow_pagefault)
			kunmap(dst_page + i);
		else
			kunmap_atomic(page_kaddr);
4240 4241 4242 4243 4244 4245 4246 4247 4248

		ret_val -= (PAGE_SIZE - rc);
		if (rc)
			break;

		cond_resched();
	}
	return ret_val;
}
A
Andrea Arcangeli 已提交
4249
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4250

4251
#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4252 4253 4254 4255 4256 4257 4258 4259 4260

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);
}

4261
bool ptlock_alloc(struct page *page)
4262 4263 4264
{
	spinlock_t *ptl;

4265
	ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4266 4267
	if (!ptl)
		return false;
4268
	page->ptl = ptl;
4269 4270 4271
	return true;
}

4272
void ptlock_free(struct page *page)
4273
{
4274
	kmem_cache_free(page_ptl_cachep, page->ptl);
4275 4276
}
#endif