kernel-ark/mm/memory.c
Minchan Kim 1a8018fb4c mm: move swap-in anonymous page into active list
Every swap-in anonymous page starts from inactive lru list's head.  It
should be activated unconditionally when VM decide to reclaim because
page table entry for the page always usually has marked accessed bit.
Thus, their window size for getting a new referece is 2 * NR_inactive +
NR_active while others is NR_inactive + NR_active.

It's not fair that it has more chance to be referenced compared to other
newly allocated page which starts from active lru list's head.

Johannes:

: The page can still have a valid copy on the swap device, so prefering to
: reclaim that page over a fresh one could make sense.  But as you point
: out, having it start inactive instead of active actually ends up giving it
: *more* LRU time, and that seems to be without justification.

Rik:

: The reason newly read in swap cache pages start on the inactive list is
: that we do some amount of read-around, and do not know which pages will
: get used.
:
: However, immediately activating the ones that DO get used, like your patch
: does, is the right thing to do.

Link: http://lkml.kernel.org/r/1469762740-17860-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-02 17:31:41 -04:00

4103 lines
110 KiB
C

/*
* linux/mm/memory.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*/
/*
* demand-loading started 01.12.91 - seems it is high on the list of
* things wanted, and it should be easy to implement. - Linus
*/
/*
* Ok, demand-loading was easy, shared pages a little bit tricker. Shared
* pages started 02.12.91, seems to work. - Linus.
*
* Tested sharing by executing about 30 /bin/sh: under the old kernel it
* would have taken more than the 6M I have free, but it worked well as
* far as I could see.
*
* Also corrected some "invalidate()"s - I wasn't doing enough of them.
*/
/*
* Real VM (paging to/from disk) started 18.12.91. Much more work and
* thought has to go into this. Oh, well..
* 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
* Found it. Everything seems to work now.
* 20.12.91 - Ok, making the swap-device changeable like the root.
*/
/*
* 05.04.94 - Multi-page memory management added for v1.1.
* Idea by Alex Bligh (alex@cconcepts.co.uk)
*
* 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
* (Gerhard.Wichert@pdb.siemens.de)
*
* Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
*/
#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/ksm.h>
#include <linux/rmap.h>
#include <linux/export.h>
#include <linux/delayacct.h>
#include <linux/init.h>
#include <linux/pfn_t.h>
#include <linux/writeback.h>
#include <linux/memcontrol.h>
#include <linux/mmu_notifier.h>
#include <linux/kallsyms.h>
#include <linux/swapops.h>
#include <linux/elf.h>
#include <linux/gfp.h>
#include <linux/migrate.h>
#include <linux/string.h>
#include <linux/dma-debug.h>
#include <linux/debugfs.h>
#include <linux/userfaultfd_k.h>
#include <linux/dax.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>
#include "internal.h"
#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
#endif
#ifndef CONFIG_NEED_MULTIPLE_NODES
/* use the per-pgdat data instead for discontigmem - mbligh */
unsigned long max_mapnr;
struct page *mem_map;
EXPORT_SYMBOL(max_mapnr);
EXPORT_SYMBOL(mem_map);
#endif
/*
* A number of key systems in x86 including ioremap() rely on the assumption
* that high_memory defines the upper bound on direct map memory, then end
* of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
* highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
* and ZONE_HIGHMEM.
*/
void * high_memory;
EXPORT_SYMBOL(high_memory);
/*
* 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
static int __init disable_randmaps(char *s)
{
randomize_va_space = 0;
return 1;
}
__setup("norandmaps", disable_randmaps);
unsigned long zero_pfn __read_mostly;
unsigned long highest_memmap_pfn __read_mostly;
EXPORT_SYMBOL(zero_pfn);
/*
* 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);
#if defined(SPLIT_RSS_COUNTING)
void sync_mm_rss(struct mm_struct *mm)
{
int i;
for (i = 0; i < NR_MM_COUNTERS; i++) {
if (current->rss_stat.count[i]) {
add_mm_counter(mm, i, current->rss_stat.count[i]);
current->rss_stat.count[i] = 0;
}
}
current->rss_stat.events = 0;
}
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))
sync_mm_rss(task->mm);
}
#else /* SPLIT_RSS_COUNTING */
#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)
{
}
#endif /* SPLIT_RSS_COUNTING */
#ifdef HAVE_GENERIC_MMU_GATHER
static bool tlb_next_batch(struct mmu_gather *tlb)
{
struct mmu_gather_batch *batch;
batch = tlb->active;
if (batch->next) {
tlb->active = batch->next;
return true;
}
if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
return false;
batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
if (!batch)
return false;
tlb->batch_count++;
batch->next = NULL;
batch->nr = 0;
batch->max = MAX_GATHER_BATCH;
tlb->active->next = batch;
tlb->active = batch;
return true;
}
/* 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).
*/
void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
{
tlb->mm = mm;
/* Is it from 0 to ~0? */
tlb->fullmm = !(start | (end+1));
tlb->need_flush_all = 0;
tlb->local.next = NULL;
tlb->local.nr = 0;
tlb->local.max = ARRAY_SIZE(tlb->__pages);
tlb->active = &tlb->local;
tlb->batch_count = 0;
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb->batch = NULL;
#endif
tlb->page_size = 0;
__tlb_reset_range(tlb);
}
static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
if (!tlb->end)
return;
tlb_flush(tlb);
mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb_table_flush(tlb);
#endif
__tlb_reset_range(tlb);
}
static void tlb_flush_mmu_free(struct mmu_gather *tlb)
{
struct mmu_gather_batch *batch;
for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
free_pages_and_swap_cache(batch->pages, batch->nr);
batch->nr = 0;
}
tlb->active = &tlb->local;
}
void tlb_flush_mmu(struct mmu_gather *tlb)
{
tlb_flush_mmu_tlbonly(tlb);
tlb_flush_mmu_free(tlb);
}
/* 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().
*returns true if the caller should flush.
*/
bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
{
struct mmu_gather_batch *batch;
VM_BUG_ON(!tlb->end);
if (!tlb->page_size)
tlb->page_size = page_size;
else {
if (page_size != tlb->page_size)
return true;
}
batch = tlb->active;
if (batch->nr == batch->max) {
if (!tlb_next_batch(tlb))
return true;
batch = tlb->active;
}
VM_BUG_ON_PAGE(batch->nr > batch->max, page);
batch->pages[batch->nr++] = page;
return false;
}
#endif /* HAVE_GENERIC_MMU_GATHER */
#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);
}
#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
/*
* Note: this doesn't free the actual pages themselves. That
* has been handled earlier when unmapping all the memory regions.
*/
static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
unsigned long addr)
{
pgtable_t token = pmd_pgtable(*pmd);
pmd_clear(pmd);
pte_free_tlb(tlb, token, addr);
atomic_long_dec(&tlb->mm->nr_ptes);
}
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)
{
pmd_t *pmd;
unsigned long next;
unsigned long start;
start = addr;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
free_pte_range(tlb, pmd, addr);
} while (pmd++, addr = next, addr != end);
start &= PUD_MASK;
if (start < floor)
return;
if (ceiling) {
ceiling &= PUD_MASK;
if (!ceiling)
return;
}
if (end - 1 > ceiling - 1)
return;
pmd = pmd_offset(pud, start);
pud_clear(pud);
pmd_free_tlb(tlb, pmd, start);
mm_dec_nr_pmds(tlb->mm);
}
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)
{
pud_t *pud;
unsigned long next;
unsigned long start;
start = addr;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
free_pmd_range(tlb, pud, addr, next, floor, ceiling);
} while (pud++, addr = next, addr != end);
start &= PGDIR_MASK;
if (start < floor)
return;
if (ceiling) {
ceiling &= PGDIR_MASK;
if (!ceiling)
return;
}
if (end - 1 > ceiling - 1)
return;
pud = pud_offset(pgd, start);
pgd_clear(pgd);
pud_free_tlb(tlb, pud, start);
}
/*
* This function frees user-level page tables of a process.
*/
void free_pgd_range(struct mmu_gather *tlb,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
pgd_t *pgd;
unsigned long next;
/*
* 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.
*/
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;
pgd = pgd_offset(tlb->mm, addr);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
free_pud_range(tlb, pgd, addr, next, floor, ceiling);
} while (pgd++, addr = next, addr != end);
}
void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
unsigned long floor, unsigned long ceiling)
{
while (vma) {
struct vm_area_struct *next = vma->vm_next;
unsigned long addr = vma->vm_start;
/*
* Hide vma from rmap and truncate_pagecache before freeing
* pgtables
*/
unlink_anon_vmas(vma);
unlink_file_vma(vma);
if (is_vm_hugetlb_page(vma)) {
hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
floor, next? next->vm_start: ceiling);
} else {
/*
* Optimization: gather nearby vmas into one call down
*/
while (next && next->vm_start <= vma->vm_end + PMD_SIZE
&& !is_vm_hugetlb_page(next)) {
vma = next;
next = vma->vm_next;
unlink_anon_vmas(vma);
unlink_file_vma(vma);
}
free_pgd_range(tlb, addr, vma->vm_end,
floor, next? next->vm_start: ceiling);
}
vma = next;
}
}
int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
{
spinlock_t *ptl;
pgtable_t new = pte_alloc_one(mm, address);
if (!new)
return -ENOMEM;
/*
* 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 */
ptl = pmd_lock(mm, pmd);
if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
atomic_long_inc(&mm->nr_ptes);
pmd_populate(mm, pmd, new);
new = NULL;
}
spin_unlock(ptl);
if (new)
pte_free(mm, new);
return 0;
}
int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
{
pte_t *new = pte_alloc_one_kernel(&init_mm, address);
if (!new)
return -ENOMEM;
smp_wmb(); /* See comment in __pte_alloc */
spin_lock(&init_mm.page_table_lock);
if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
pmd_populate_kernel(&init_mm, pmd, new);
new = NULL;
}
spin_unlock(&init_mm.page_table_lock);
if (new)
pte_free_kernel(&init_mm, new);
return 0;
}
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)
{
int i;
if (current->mm == mm)
sync_mm_rss(mm);
for (i = 0; i < NR_MM_COUNTERS; i++)
if (rss[i])
add_mm_counter(mm, i, rss[i]);
}
/*
* 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.
*
* The calling function must still handle the error.
*/
static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
pte_t pte, struct page *page)
{
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;
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) {
pr_alert("BUG: Bad page map: %lu messages suppressed\n",
nr_unshown);
nr_unshown = 0;
}
nr_shown = 0;
}
if (nr_shown++ == 0)
resume = jiffies + 60 * HZ;
mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
index = linear_page_index(vma, addr);
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));
if (page)
dump_page(page, "bad pte");
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);
/*
* Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
*/
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);
dump_stack();
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
}
/*
* vm_normal_page -- This function gets the "struct page" associated with a pte.
*
* "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.
*
* 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.
*
* 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
* set, and the vm_pgoff will point to the first PFN mapped: thus every special
* mapping will always honor the rule
*
* pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
*
* 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).
*
*
* In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
*
* 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.
*
*/
#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)
{
unsigned long pfn = pte_pfn(pte);
if (HAVE_PTE_SPECIAL) {
if (likely(!pte_special(pte)))
goto check_pfn;
if (vma->vm_ops && vma->vm_ops->find_special_page)
return vma->vm_ops->find_special_page(vma, addr);
if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
return NULL;
if (!is_zero_pfn(pfn))
print_bad_pte(vma, addr, pte, NULL);
return NULL;
}
/* !HAVE_PTE_SPECIAL case follows: */
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;
check_pfn:
if (unlikely(pfn > highest_memmap_pfn)) {
print_bad_pte(vma, addr, pte, NULL);
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);
}
#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
/*
* 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.
*/
static inline unsigned long
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
unsigned long addr, int *rss)
{
unsigned long vm_flags = vma->vm_flags;
pte_t pte = *src_pte;
struct page *page;
/* pte contains position in swap or file, so copy. */
if (unlikely(!pte_present(pte))) {
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);
rss[mm_counter(page)]++;
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);
}
}
goto out_set_pte;
}
/*
* If it's a COW mapping, write protect it both
* in the parent and the child
*/
if (is_cow_mapping(vm_flags)) {
ptep_set_wrprotect(src_mm, addr, src_pte);
pte = pte_wrprotect(pte);
}
/*
* 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);
page = vm_normal_page(vma, addr, pte);
if (page) {
get_page(page);
page_dup_rmap(page, false);
rss[mm_counter(page)]++;
}
out_set_pte:
set_pte_at(dst_mm, addr, dst_pte, pte);
return 0;
}
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
pte_t *orig_src_pte, *orig_dst_pte;
pte_t *src_pte, *dst_pte;
spinlock_t *src_ptl, *dst_ptl;
int progress = 0;
int rss[NR_MM_COUNTERS];
swp_entry_t entry = (swp_entry_t){0};
again:
init_rss_vec(rss);
dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
if (!dst_pte)
return -ENOMEM;
src_pte = pte_offset_map(src_pmd, addr);
src_ptl = pte_lockptr(src_mm, src_pmd);
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
orig_src_pte = src_pte;
orig_dst_pte = dst_pte;
arch_enter_lazy_mmu_mode();
do {
/*
* We are holding two locks at this point - either of them
* could generate latencies in another task on another CPU.
*/
if (progress >= 32) {
progress = 0;
if (need_resched() ||
spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
break;
}
if (pte_none(*src_pte)) {
progress++;
continue;
}
entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
vma, addr, rss);
if (entry.val)
break;
progress += 8;
} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
spin_unlock(src_ptl);
pte_unmap(orig_src_pte);
add_mm_rss_vec(dst_mm, rss);
pte_unmap_unlock(orig_dst_pte, dst_ptl);
cond_resched();
if (entry.val) {
if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
return -ENOMEM;
progress = 0;
}
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);
if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
int err;
VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
err = copy_huge_pmd(dst_mm, src_mm,
dst_pmd, src_pmd, addr, vma);
if (err == -ENOMEM)
return -ENOMEM;
if (!err)
continue;
/* fall through */
}
if (pmd_none_or_clear_bad(src_pmd))
continue;
if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
vma, addr, next))
return -ENOMEM;
} while (dst_pmd++, src_pmd++, addr = next, addr != end);
return 0;
}
static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
pud_t *src_pud, *dst_pud;
unsigned long next;
dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
if (!dst_pud)
return -ENOMEM;
src_pud = pud_offset(src_pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(src_pud))
continue;
if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
vma, addr, next))
return -ENOMEM;
} while (dst_pud++, src_pud++, addr = next, addr != end);
return 0;
}
int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
struct vm_area_struct *vma)
{
pgd_t *src_pgd, *dst_pgd;
unsigned long next;
unsigned long addr = vma->vm_start;
unsigned long end = vma->vm_end;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
bool is_cow;
int ret;
/*
* 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.
*/
if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
!vma->anon_vma)
return 0;
if (is_vm_hugetlb_page(vma))
return copy_hugetlb_page_range(dst_mm, src_mm, vma);
if (unlikely(vma->vm_flags & VM_PFNMAP)) {
/*
* We do not free on error cases below as remove_vma
* gets called on error from higher level routine
*/
ret = track_pfn_copy(vma);
if (ret)
return ret;
}
/*
* 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.
*/
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);
ret = 0;
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;
if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
vma, addr, next))) {
ret = -ENOMEM;
break;
}
} while (dst_pgd++, src_pgd++, addr = next, addr != end);
if (is_cow)
mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
return ret;
}
static unsigned long zap_pte_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
struct zap_details *details)
{
struct mm_struct *mm = tlb->mm;
int force_flush = 0;
int rss[NR_MM_COUNTERS];
spinlock_t *ptl;
pte_t *start_pte;
pte_t *pte;
swp_entry_t entry;
struct page *pending_page = NULL;
again:
init_rss_vec(rss);
start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
pte = start_pte;
arch_enter_lazy_mmu_mode();
do {
pte_t ptent = *pte;
if (pte_none(ptent)) {
continue;
}
if (pte_present(ptent)) {
struct page *page;
page = vm_normal_page(vma, addr, ptent);
if (unlikely(details) && page) {
/*
* unmap_shared_mapping_pages() wants to
* invalidate cache without truncating:
* unmap shared but keep private pages.
*/
if (details->check_mapping &&
details->check_mapping != page_rmapping(page))
continue;
}
ptent = ptep_get_and_clear_full(mm, addr, pte,
tlb->fullmm);
tlb_remove_tlb_entry(tlb, pte, addr);
if (unlikely(!page))
continue;
if (!PageAnon(page)) {
if (pte_dirty(ptent)) {
/*
* oom_reaper cannot tear down dirty
* pages
*/
if (unlikely(details && details->ignore_dirty))
continue;
force_flush = 1;
set_page_dirty(page);
}
if (pte_young(ptent) &&
likely(!(vma->vm_flags & VM_SEQ_READ)))
mark_page_accessed(page);
}
rss[mm_counter(page)]--;
page_remove_rmap(page, false);
if (unlikely(page_mapcount(page) < 0))
print_bad_pte(vma, addr, ptent, page);
if (unlikely(__tlb_remove_page(tlb, page))) {
force_flush = 1;
pending_page = page;
addr += PAGE_SIZE;
break;
}
continue;
}
/* only check swap_entries if explicitly asked for in details */
if (unlikely(details && !details->check_swap_entries))
continue;
entry = pte_to_swp_entry(ptent);
if (!non_swap_entry(entry))
rss[MM_SWAPENTS]--;
else if (is_migration_entry(entry)) {
struct page *page;
page = migration_entry_to_page(entry);
rss[mm_counter(page)]--;
}
if (unlikely(!free_swap_and_cache(entry)))
print_bad_pte(vma, addr, ptent, NULL);
pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
} while (pte++, addr += PAGE_SIZE, addr != end);
add_mm_rss_vec(mm, rss);
arch_leave_lazy_mmu_mode();
/* Do the actual TLB flush before dropping ptl */
if (force_flush)
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);
if (pending_page) {
/* remove the page with new size */
__tlb_remove_pte_page(tlb, pending_page);
pending_page = NULL;
}
if (addr != end)
goto again;
}
return addr;
}
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pud_t *pud,
unsigned long addr, unsigned long end,
struct zap_details *details)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE) {
VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
split_huge_pmd(vma, pmd, addr);
} else if (zap_huge_pmd(tlb, vma, pmd, addr))
goto next;
/* fall through */
}
/*
* 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;
next = zap_pte_range(tlb, vma, pmd, addr, next, details);
next:
cond_resched();
} while (pmd++, addr = next, addr != end);
return addr;
}
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pgd_t *pgd,
unsigned long addr, unsigned long end,
struct zap_details *details)
{
pud_t *pud;
unsigned long next;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
next = zap_pmd_range(tlb, vma, pud, addr, next, details);
} while (pud++, addr = next, addr != end);
return addr;
}
void unmap_page_range(struct mmu_gather *tlb,
struct vm_area_struct *vma,
unsigned long addr, unsigned long end,
struct zap_details *details)
{
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);
if (pgd_none_or_clear_bad(pgd))
continue;
next = zap_pud_range(tlb, vma, pgd, addr, next, details);
} while (pgd++, addr = next, addr != end);
tlb_end_vma(tlb, vma);
}
static void unmap_single_vma(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start_addr,
unsigned long end_addr,
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;
if (vma->vm_file)
uprobe_munmap(vma, start, end);
if (unlikely(vma->vm_flags & VM_PFNMAP))
untrack_pfn(vma, 0, 0);
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
* cleanup path of mmap_region. When
* hugetlbfs ->mmap method fails,
* mmap_region() nullifies vma->vm_file
* before calling this function to clean up.
* Since no pte has actually been setup, it is
* safe to do nothing in this case.
*/
if (vma->vm_file) {
i_mmap_lock_write(vma->vm_file->f_mapping);
__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
i_mmap_unlock_write(vma->vm_file->f_mapping);
}
} else
unmap_page_range(tlb, vma, start, end, details);
}
}
/**
* unmap_vmas - unmap a range of memory covered by a list of vma's
* @tlb: address of the caller's struct mmu_gather
* @vma: the starting vma
* @start_addr: virtual address at which to start unmapping
* @end_addr: virtual address at which to end unmapping
*
* Unmap all pages in the vma list.
*
* 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.
*/
void unmap_vmas(struct mmu_gather *tlb,
struct vm_area_struct *vma, unsigned long start_addr,
unsigned long end_addr)
{
struct mm_struct *mm = vma->vm_mm;
mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
}
/**
* zap_page_range - remove user pages in a given range
* @vma: vm_area_struct holding the applicable pages
* @start: starting address of pages to zap
* @size: number of bytes to zap
* @details: details of shared cache invalidation
*
* Caller must protect the VMA list
*/
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
unsigned long size, struct zap_details *details)
{
struct mm_struct *mm = vma->vm_mm;
struct mmu_gather tlb;
unsigned long end = start + size;
lru_add_drain();
tlb_gather_mmu(&tlb, mm, start, end);
update_hiwater_rss(mm);
mmu_notifier_invalidate_range_start(mm, start, end);
for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
unmap_single_vma(&tlb, vma, start, end, details);
mmu_notifier_invalidate_range_end(mm, start, end);
tlb_finish_mmu(&tlb, start, end);
}
/**
* zap_page_range_single - remove user pages in a given range
* @vma: vm_area_struct holding the applicable pages
* @address: starting address of pages to zap
* @size: number of bytes to zap
* @details: details of shared cache invalidation
*
* The range must fit into one VMA.
*/
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
unsigned long size, struct zap_details *details)
{
struct mm_struct *mm = vma->vm_mm;
struct mmu_gather tlb;
unsigned long end = address + size;
lru_add_drain();
tlb_gather_mmu(&tlb, mm, address, end);
update_hiwater_rss(mm);
mmu_notifier_invalidate_range_start(mm, address, end);
unmap_single_vma(&tlb, vma, address, end, details);
mmu_notifier_invalidate_range_end(mm, address, end);
tlb_finish_mmu(&tlb, address, end);
}
/**
* 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;
zap_page_range_single(vma, address, size, NULL);
return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
spinlock_t **ptl)
{
pgd_t * pgd = pgd_offset(mm, addr);
pud_t * pud = pud_alloc(mm, pgd, addr);
if (pud) {
pmd_t * pmd = pmd_alloc(mm, pud, addr);
if (pmd) {
VM_BUG_ON(pmd_trans_huge(*pmd));
return pte_alloc_map_lock(mm, pmd, addr, ptl);
}
}
return NULL;
}
/*
* 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.
*/
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
struct page *page, pgprot_t prot)
{
struct mm_struct *mm = vma->vm_mm;
int retval;
pte_t *pte;
spinlock_t *ptl;
retval = -EINVAL;
if (PageAnon(page))
goto out;
retval = -ENOMEM;
flush_dcache_page(page);
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.. */
get_page(page);
inc_mm_counter_fast(mm, mm_counter_file(page));
page_add_file_rmap(page, false);
set_pte_at(mm, addr, pte, mk_pte(page, prot));
retval = 0;
pte_unmap_unlock(pte, ptl);
return retval;
out_unlock:
pte_unmap_unlock(pte, ptl);
out:
return retval;
}
/**
* 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
*
* 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
* (see split_page()).
*
* 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.
*
* 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.
*/
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
struct page *page)
{
if (addr < vma->vm_start || addr >= vma->vm_end)
return -EFAULT;
if (!page_count(page))
return -EINVAL;
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;
}
return insert_page(vma, addr, page, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_insert_page);
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn, pgprot_t prot)
{
struct mm_struct *mm = vma->vm_mm;
int retval;
pte_t *pte, entry;
spinlock_t *ptl;
retval = -ENOMEM;
pte = get_locked_pte(mm, addr, &ptl);
if (!pte)
goto out;
retval = -EBUSY;
if (!pte_none(*pte))
goto out_unlock;
/* Ok, finally just insert the thing.. */
if (pfn_t_devmap(pfn))
entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
else
entry = pte_mkspecial(pfn_t_pte(pfn, prot));
set_pte_at(mm, addr, pte, entry);
update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
retval = 0;
out_unlock:
pte_unmap_unlock(pte, ptl);
out:
return retval;
}
/**
* 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
*
* Similar to vm_insert_page, this allows drivers to insert individual pages
* 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.
*
* 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.
*/
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn)
{
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)
{
int ret;
/*
* 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.
*/
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));
if (addr < vma->vm_start || addr >= vma->vm_end)
return -EFAULT;
if (track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)))
return -EINVAL;
ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
return ret;
}
EXPORT_SYMBOL(vm_insert_pfn_prot);
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn)
{
BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
if (addr < vma->vm_start || addr >= vma->vm_end)
return -EFAULT;
/*
* 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
* 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.
*/
if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
struct page *page;
/*
* 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));
return insert_page(vma, addr, page, vma->vm_page_prot);
}
return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
}
EXPORT_SYMBOL(vm_insert_mixed);
/*
* 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;
spinlock_t *ptl;
pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
if (!pte)
return -ENOMEM;
arch_enter_lazy_mmu_mode();
do {
BUG_ON(!pte_none(*pte));
set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
pfn++;
} while (pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
pte_unmap_unlock(pte - 1, ptl);
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;
VM_BUG_ON(pmd_trans_huge(*pmd));
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;
}
/**
* 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.
*/
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;
unsigned long end = addr + PAGE_ALIGN(size);
struct mm_struct *mm = vma->vm_mm;
unsigned long remap_pfn = pfn;
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).
* 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.
* VM_DONTEXPAND
* Disable vma merging and expanding with mremap().
* VM_DONTDUMP
* Omit vma from core dump, even when VM_IO turned off.
*
* 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".
* See vm_normal_page() for details.
*/
if (is_cow_mapping(vma->vm_flags)) {
if (addr != vma->vm_start || end != vma->vm_end)
return -EINVAL;
vma->vm_pgoff = pfn;
}
err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
if (err)
return -EINVAL;
vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
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);
if (err)
untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
return err;
}
EXPORT_SYMBOL(remap_pfn_range);
/**
* 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);
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;
pgtable_t token;
spinlock_t *uninitialized_var(ptl);
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));
arch_enter_lazy_mmu_mode();
token = pmd_pgtable(*pmd);
do {
err = fn(pte++, token, addr, data);
if (err)
break;
} while (addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
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;
BUG_ON(pud_huge(*pud));
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;
unsigned long end = addr + size;
int err;
if (WARN_ON(addr >= end))
return -EINVAL;
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);
return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);
/*
* 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;
* and do_anonymous_page can safely check later on).
*/
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
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)) {
spinlock_t *ptl = pte_lockptr(mm, pmd);
spin_lock(ptl);
same = pte_same(*page_table, orig_pte);
spin_unlock(ptl);
}
#endif
pte_unmap(page_table);
return same;
}
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
{
debug_dma_assert_idle(src);
/*
* 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)) {
void *kaddr = kmap_atomic(dst);
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))
clear_page(kaddr);
kunmap_atomic(kaddr);
flush_dcache_page(dst);
} else
copy_user_highpage(dst, src, va, vma);
}
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;
}
/*
* Notify the address space that the page is about to become writable so that
* it can prohibit this or wait for the page to get into an appropriate state.
*
* We do this without the lock held, so that it can sleep if it needs to.
*/
static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
unsigned long address)
{
struct vm_fault vmf;
int ret;
vmf.virtual_address = (void __user *)(address & PAGE_MASK);
vmf.pgoff = page->index;
vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
vmf.gfp_mask = __get_fault_gfp_mask(vma);
vmf.page = page;
vmf.cow_page = NULL;
ret = vma->vm_ops->page_mkwrite(vma, &vmf);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
return ret;
if (unlikely(!(ret & VM_FAULT_LOCKED))) {
lock_page(page);
if (!page->mapping) {
unlock_page(page);
return 0; /* retry */
}
ret |= VM_FAULT_LOCKED;
} else
VM_BUG_ON_PAGE(!PageLocked(page), page);
return ret;
}
/*
* Handle write page faults for pages that can be reused in the current vma
*
* This can happen either due to the mapping being with the VM_SHARED flag,
* or due to us being the last reference standing to the page. In either
* case, all we need to do here is to mark the page as writable and update
* any related book-keeping.
*/
static inline int wp_page_reuse(struct fault_env *fe, pte_t orig_pte,
struct page *page, int page_mkwrite, int dirty_shared)
__releases(fe->ptl)
{
struct vm_area_struct *vma = fe->vma;
pte_t entry;
/*
* Clear the pages cpupid information as the existing
* information potentially belongs to a now completely
* unrelated process.
*/
if (page)
page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
flush_cache_page(vma, fe->address, pte_pfn(orig_pte));
entry = pte_mkyoung(orig_pte);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
if (ptep_set_access_flags(vma, fe->address, fe->pte, entry, 1))
update_mmu_cache(vma, fe->address, fe->pte);
pte_unmap_unlock(fe->pte, fe->ptl);
if (dirty_shared) {
struct address_space *mapping;
int dirtied;
if (!page_mkwrite)
lock_page(page);
dirtied = set_page_dirty(page);
VM_BUG_ON_PAGE(PageAnon(page), page);
mapping = page->mapping;
unlock_page(page);
put_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);
}
return VM_FAULT_WRITE;
}
/*
* Handle the case of a page which we actually need to copy to a new page.
*
* Called with mmap_sem locked and the old page referenced, but
* without the ptl held.
*
* High level logic flow:
*
* - Allocate a page, copy the content of the old page to the new one.
* - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
* - Take the PTL. If the pte changed, bail out and release the allocated page
* - If the pte is still the way we remember it, update the page table and all
* relevant references. This includes dropping the reference the page-table
* held to the old page, as well as updating the rmap.
* - In any case, unlock the PTL and drop the reference we took to the old page.
*/
static int wp_page_copy(struct fault_env *fe, pte_t orig_pte,
struct page *old_page)
{
struct vm_area_struct *vma = fe->vma;
struct mm_struct *mm = vma->vm_mm;
struct page *new_page = NULL;
pte_t entry;
int page_copied = 0;
const unsigned long mmun_start = fe->address & PAGE_MASK;
const unsigned long mmun_end = mmun_start + PAGE_SIZE;
struct mem_cgroup *memcg;
if (unlikely(anon_vma_prepare(vma)))
goto oom;
if (is_zero_pfn(pte_pfn(orig_pte))) {
new_page = alloc_zeroed_user_highpage_movable(vma, fe->address);
if (!new_page)
goto oom;
} else {
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
fe->address);
if (!new_page)
goto oom;
cow_user_page(new_page, old_page, fe->address, vma);
}
if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
goto oom_free_new;
__SetPageUptodate(new_page);
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
/*
* Re-check the pte - we dropped the lock
*/
fe->pte = pte_offset_map_lock(mm, fe->pmd, fe->address, &fe->ptl);
if (likely(pte_same(*fe->pte, orig_pte))) {
if (old_page) {
if (!PageAnon(old_page)) {
dec_mm_counter_fast(mm,
mm_counter_file(old_page));
inc_mm_counter_fast(mm, MM_ANONPAGES);
}
} else {
inc_mm_counter_fast(mm, MM_ANONPAGES);
}
flush_cache_page(vma, fe->address, pte_pfn(orig_pte));
entry = mk_pte(new_page, vma->vm_page_prot);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
/*
* Clear the pte entry and flush it first, before updating the
* pte with the new entry. This will avoid a race condition
* seen in the presence of one thread doing SMC and another
* thread doing COW.
*/
ptep_clear_flush_notify(vma, fe->address, fe->pte);
page_add_new_anon_rmap(new_page, vma, fe->address, false);
mem_cgroup_commit_charge(new_page, memcg, false, false);
lru_cache_add_active_or_unevictable(new_page, vma);
/*
* We call the notify macro here because, when using secondary
* mmu page tables (such as kvm shadow page tables), we want the
* new page to be mapped directly into the secondary page table.
*/
set_pte_at_notify(mm, fe->address, fe->pte, entry);
update_mmu_cache(vma, fe->address, fe->pte);
if (old_page) {
/*
* Only after switching the pte to the new page may
* we remove the mapcount here. Otherwise another
* process may come and find the rmap count decremented
* before the pte is switched to the new page, and
* "reuse" the old page writing into it while our pte
* here still points into it and can be read by other
* threads.
*
* The critical issue is to order this
* page_remove_rmap with the ptp_clear_flush above.
* Those stores are ordered by (if nothing else,)
* the barrier present in the atomic_add_negative
* in page_remove_rmap.
*
* Then the TLB flush in ptep_clear_flush ensures that
* no process can access the old page before the
* decremented mapcount is visible. And the old page
* cannot be reused until after the decremented
* mapcount is visible. So transitively, TLBs to
* old page will be flushed before it can be reused.
*/
page_remove_rmap(old_page, false);
}
/* Free the old page.. */
new_page = old_page;
page_copied = 1;
} else {
mem_cgroup_cancel_charge(new_page, memcg, false);
}
if (new_page)
put_page(new_page);
pte_unmap_unlock(fe->pte, fe->ptl);
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
if (old_page) {
/*
* Don't let another task, with possibly unlocked vma,
* keep the mlocked page.
*/
if (page_copied && (vma->vm_flags & VM_LOCKED)) {
lock_page(old_page); /* LRU manipulation */
if (PageMlocked(old_page))
munlock_vma_page(old_page);
unlock_page(old_page);
}
put_page(old_page);
}
return page_copied ? VM_FAULT_WRITE : 0;
oom_free_new:
put_page(new_page);
oom:
if (old_page)
put_page(old_page);
return VM_FAULT_OOM;
}
/*
* Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
* mapping
*/
static int wp_pfn_shared(struct fault_env *fe, pte_t orig_pte)
{
struct vm_area_struct *vma = fe->vma;
if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
struct vm_fault vmf = {
.page = NULL,
.pgoff = linear_page_index(vma, fe->address),
.virtual_address =
(void __user *)(fe->address & PAGE_MASK),
.flags = FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE,
};
int ret;
pte_unmap_unlock(fe->pte, fe->ptl);
ret = vma->vm_ops->pfn_mkwrite(vma, &vmf);
if (ret & VM_FAULT_ERROR)
return ret;
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
&fe->ptl);
/*
* We might have raced with another page fault while we
* released the pte_offset_map_lock.
*/
if (!pte_same(*fe->pte, orig_pte)) {
pte_unmap_unlock(fe->pte, fe->ptl);
return 0;
}
}
return wp_page_reuse(fe, orig_pte, NULL, 0, 0);
}
static int wp_page_shared(struct fault_env *fe, pte_t orig_pte,
struct page *old_page)
__releases(fe->ptl)
{
struct vm_area_struct *vma = fe->vma;
int page_mkwrite = 0;
get_page(old_page);
if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
int tmp;
pte_unmap_unlock(fe->pte, fe->ptl);
tmp = do_page_mkwrite(vma, old_page, fe->address);
if (unlikely(!tmp || (tmp &
(VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
put_page(old_page);
return tmp;
}
/*
* Since we dropped the lock we need to revalidate
* the PTE as someone else may have changed it. If
* they did, we just return, as we can count on the
* MMU to tell us if they didn't also make it writable.
*/
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
&fe->ptl);
if (!pte_same(*fe->pte, orig_pte)) {
unlock_page(old_page);
pte_unmap_unlock(fe->pte, fe->ptl);
put_page(old_page);
return 0;
}
page_mkwrite = 1;
}
return wp_page_reuse(fe, orig_pte, old_page, page_mkwrite, 1);
}
/*
* 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.
*
* 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.
*/
static int do_wp_page(struct fault_env *fe, pte_t orig_pte)
__releases(fe->ptl)
{
struct vm_area_struct *vma = fe->vma;
struct page *old_page;
old_page = vm_normal_page(vma, fe->address, orig_pte);
if (!old_page) {
/*
* VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
* VM_PFNMAP VMA.
*
* We should not cow pages in a shared writeable mapping.
* Just mark the pages writable and/or call ops->pfn_mkwrite.
*/
if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
(VM_WRITE|VM_SHARED))
return wp_pfn_shared(fe, orig_pte);
pte_unmap_unlock(fe->pte, fe->ptl);
return wp_page_copy(fe, orig_pte, old_page);
}
/*
* Take out anonymous pages first, anonymous shared vmas are
* not dirty accountable.
*/
if (PageAnon(old_page) && !PageKsm(old_page)) {
int total_mapcount;
if (!trylock_page(old_page)) {
get_page(old_page);
pte_unmap_unlock(fe->pte, fe->ptl);
lock_page(old_page);
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd,
fe->address, &fe->ptl);
if (!pte_same(*fe->pte, orig_pte)) {
unlock_page(old_page);
pte_unmap_unlock(fe->pte, fe->ptl);
put_page(old_page);
return 0;
}
put_page(old_page);
}
if (reuse_swap_page(old_page, &total_mapcount)) {
if (total_mapcount == 1) {
/*
* The page is all ours. Move it to
* our anon_vma so the rmap code will
* not search our parent or siblings.
* Protected against the rmap code by
* the page lock.
*/
page_move_anon_rmap(old_page, vma);
}
unlock_page(old_page);
return wp_page_reuse(fe, orig_pte, old_page, 0, 0);
}
unlock_page(old_page);
} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
(VM_WRITE|VM_SHARED))) {
return wp_page_shared(fe, orig_pte, old_page);
}
/*
* Ok, we need to copy. Oh, well..
*/
get_page(old_page);
pte_unmap_unlock(fe->pte, fe->ptl);
return wp_page_copy(fe, orig_pte, old_page);
}
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
unsigned long start_addr, unsigned long end_addr,
struct zap_details *details)
{
zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
}
static inline void unmap_mapping_range_tree(struct rb_root *root,
struct zap_details *details)
{
struct vm_area_struct *vma;
pgoff_t vba, vea, zba, zea;
vma_interval_tree_foreach(vma, root,
details->first_index, details->last_index) {
vba = vma->vm_pgoff;
vea = vba + vma_pages(vma) - 1;
zba = details->first_index;
if (zba < vba)
zba = vba;
zea = details->last_index;
if (zea > vea)
zea = vea;
unmap_mapping_range_vma(vma,
((zba - vba) << PAGE_SHIFT) + vma->vm_start,
((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
details);
}
}
/**
* unmap_mapping_range - unmap the portion of all mmaps in the specified
* address_space corresponding to the specified page range in the underlying
* file.
*
* @mapping: the address space containing mmaps to be unmapped.
* @holebegin: byte in first page to unmap, relative to the start of
* the underlying file. This will be rounded down to a PAGE_SIZE
* boundary. Note that this is different from truncate_pagecache(), which
* must keep the partial page. In contrast, we must get rid of
* partial pages.
* @holelen: size of prospective hole in bytes. This will be rounded
* up to a PAGE_SIZE boundary. A holelen of zero truncates to the
* end of the file.
* @even_cows: 1 when truncating a file, unmap even private COWed pages;
* but 0 when invalidating pagecache, don't throw away private data.
*/
void unmap_mapping_range(struct address_space *mapping,
loff_t const holebegin, loff_t const holelen, int even_cows)
{
struct zap_details details = { };
pgoff_t hba = holebegin >> PAGE_SHIFT;
pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
/* Check for overflow. */
if (sizeof(holelen) > sizeof(hlen)) {
long long holeend =
(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (holeend & ~(long long)ULONG_MAX)
hlen = ULONG_MAX - hba + 1;
}
details.check_mapping = even_cows? NULL: mapping;
details.first_index = hba;
details.last_index = hba + hlen - 1;
if (details.last_index < details.first_index)
details.last_index = ULONG_MAX;
i_mmap_lock_write(mapping);
if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
unmap_mapping_range_tree(&mapping->i_mmap, &details);
i_mmap_unlock_write(mapping);
}
EXPORT_SYMBOL(unmap_mapping_range);
/*
* 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 pte unmapped and unlocked.
*
* We return with the mmap_sem locked or unlocked in the same cases
* as does filemap_fault().
*/
int do_swap_page(struct fault_env *fe, pte_t orig_pte)
{
struct vm_area_struct *vma = fe->vma;
struct page *page, *swapcache;
struct mem_cgroup *memcg;
swp_entry_t entry;
pte_t pte;
int locked;
int exclusive = 0;
int ret = 0;
if (!pte_unmap_same(vma->vm_mm, fe->pmd, fe->pte, orig_pte))
goto out;
entry = pte_to_swp_entry(orig_pte);
if (unlikely(non_swap_entry(entry))) {
if (is_migration_entry(entry)) {
migration_entry_wait(vma->vm_mm, fe->pmd, fe->address);
} else if (is_hwpoison_entry(entry)) {
ret = VM_FAULT_HWPOISON;
} else {
print_bad_pte(vma, fe->address, orig_pte, NULL);
ret = VM_FAULT_SIGBUS;
}
goto out;
}
delayacct_set_flag(DELAYACCT_PF_SWAPIN);
page = lookup_swap_cache(entry);
if (!page) {
page = swapin_readahead(entry,
GFP_HIGHUSER_MOVABLE, vma, fe->address);
if (!page) {
/*
* Back out if somebody else faulted in this pte
* while we released the pte lock.
*/
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd,
fe->address, &fe->ptl);
if (likely(pte_same(*fe->pte, orig_pte)))
ret = VM_FAULT_OOM;
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
goto unlock;
}
/* Had to read the page from swap area: Major fault */
ret = VM_FAULT_MAJOR;
count_vm_event(PGMAJFAULT);
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
} else if (PageHWPoison(page)) {
/*
* hwpoisoned dirty swapcache pages are kept for killing
* owner processes (which may be unknown at hwpoison time)
*/
ret = VM_FAULT_HWPOISON;
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
swapcache = page;
goto out_release;
}
swapcache = page;
locked = lock_page_or_retry(page, vma->vm_mm, fe->flags);
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
if (!locked) {
ret |= VM_FAULT_RETRY;
goto out_release;
}
/*
* 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.
*/
if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
goto out_page;
page = ksm_might_need_to_copy(page, vma, fe->address);
if (unlikely(!page)) {
ret = VM_FAULT_OOM;
page = swapcache;
goto out_page;
}
if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
&memcg, false)) {
ret = VM_FAULT_OOM;
goto out_page;
}
/*
* Back out if somebody else already faulted in this pte.
*/
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
&fe->ptl);
if (unlikely(!pte_same(*fe->pte, orig_pte)))
goto out_nomap;
if (unlikely(!PageUptodate(page))) {
ret = VM_FAULT_SIGBUS;
goto out_nomap;
}
/*
* 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.
*/
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
pte = mk_pte(page, vma->vm_page_prot);
if ((fe->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
pte = maybe_mkwrite(pte_mkdirty(pte), vma);
fe->flags &= ~FAULT_FLAG_WRITE;
ret |= VM_FAULT_WRITE;
exclusive = RMAP_EXCLUSIVE;
}
flush_icache_page(vma, page);
if (pte_swp_soft_dirty(orig_pte))
pte = pte_mksoft_dirty(pte);
set_pte_at(vma->vm_mm, fe->address, fe->pte, pte);
if (page == swapcache) {
do_page_add_anon_rmap(page, vma, fe->address, exclusive);
mem_cgroup_commit_charge(page, memcg, true, false);
activate_page(page);
} else { /* ksm created a completely new copy */
page_add_new_anon_rmap(page, vma, fe->address, false);
mem_cgroup_commit_charge(page, memcg, false, false);
lru_cache_add_active_or_unevictable(page, vma);
}
swap_free(entry);
if (mem_cgroup_swap_full(page) ||
(vma->vm_flags & VM_LOCKED) || PageMlocked(page))
try_to_free_swap(page);
unlock_page(page);
if (page != swapcache) {
/*
* 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);
put_page(swapcache);
}
if (fe->flags & FAULT_FLAG_WRITE) {
ret |= do_wp_page(fe, pte);
if (ret & VM_FAULT_ERROR)
ret &= VM_FAULT_ERROR;
goto out;
}
/* No need to invalidate - it was non-present before */
update_mmu_cache(vma, fe->address, fe->pte);
unlock:
pte_unmap_unlock(fe->pte, fe->ptl);
out:
return ret;
out_nomap:
mem_cgroup_cancel_charge(page, memcg, false);
pte_unmap_unlock(fe->pte, fe->ptl);
out_page:
unlock_page(page);
out_release:
put_page(page);
if (page != swapcache) {
unlock_page(swapcache);
put_page(swapcache);
}
return ret;
}
/*
* This is like a special single-page "expand_{down|up}wards()",
* except we must first make sure that 'address{-|+}PAGE_SIZE'
* 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) {
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;
return expand_downwards(vma, address - PAGE_SIZE);
}
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;
return expand_upwards(vma, address + PAGE_SIZE);
}
return 0;
}
/*
* 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.
*/
static int do_anonymous_page(struct fault_env *fe)
{
struct vm_area_struct *vma = fe->vma;
struct mem_cgroup *memcg;
struct page *page;
pte_t entry;
/* File mapping without ->vm_ops ? */
if (vma->vm_flags & VM_SHARED)
return VM_FAULT_SIGBUS;
/* Check if we need to add a guard page to the stack */
if (check_stack_guard_page(vma, fe->address) < 0)
return VM_FAULT_SIGSEGV;
/*
* 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).
*/
if (pte_alloc(vma->vm_mm, fe->pmd, fe->address))
return VM_FAULT_OOM;
/* See the comment in pte_alloc_one_map() */
if (unlikely(pmd_trans_unstable(fe->pmd)))
return 0;
/* Use the zero-page for reads */
if (!(fe->flags & FAULT_FLAG_WRITE) &&
!mm_forbids_zeropage(vma->vm_mm)) {
entry = pte_mkspecial(pfn_pte(my_zero_pfn(fe->address),
vma->vm_page_prot));
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
&fe->ptl);
if (!pte_none(*fe->pte))
goto unlock;
/* Deliver the page fault to userland, check inside PT lock */
if (userfaultfd_missing(vma)) {
pte_unmap_unlock(fe->pte, fe->ptl);
return handle_userfault(fe, VM_UFFD_MISSING);
}
goto setpte;
}
/* Allocate our own private page. */
if (unlikely(anon_vma_prepare(vma)))
goto oom;
page = alloc_zeroed_user_highpage_movable(vma, fe->address);
if (!page)
goto oom;
if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
goto oom_free_page;
/*
* The memory barrier inside __SetPageUptodate makes sure that
* preceeding stores to the page contents become visible before
* the set_pte_at() write.
*/
__SetPageUptodate(page);
entry = mk_pte(page, vma->vm_page_prot);
if (vma->vm_flags & VM_WRITE)
entry = pte_mkwrite(pte_mkdirty(entry));
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
&fe->ptl);
if (!pte_none(*fe->pte))
goto release;
/* Deliver the page fault to userland, check inside PT lock */
if (userfaultfd_missing(vma)) {
pte_unmap_unlock(fe->pte, fe->ptl);
mem_cgroup_cancel_charge(page, memcg, false);
put_page(page);
return handle_userfault(fe, VM_UFFD_MISSING);
}
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
page_add_new_anon_rmap(page, vma, fe->address, false);
mem_cgroup_commit_charge(page, memcg, false, false);
lru_cache_add_active_or_unevictable(page, vma);
setpte:
set_pte_at(vma->vm_mm, fe->address, fe->pte, entry);
/* No need to invalidate - it was non-present before */
update_mmu_cache(vma, fe->address, fe->pte);
unlock:
pte_unmap_unlock(fe->pte, fe->ptl);
return 0;
release:
mem_cgroup_cancel_charge(page, memcg, false);
put_page(page);
goto unlock;
oom_free_page:
put_page(page);
oom:
return VM_FAULT_OOM;
}
/*
* 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().
*/
static int __do_fault(struct fault_env *fe, pgoff_t pgoff,
struct page *cow_page, struct page **page, void **entry)
{
struct vm_area_struct *vma = fe->vma;
struct vm_fault vmf;
int ret;
vmf.virtual_address = (void __user *)(fe->address & PAGE_MASK);
vmf.pgoff = pgoff;
vmf.flags = fe->flags;
vmf.page = NULL;
vmf.gfp_mask = __get_fault_gfp_mask(vma);
vmf.cow_page = cow_page;
ret = vma->vm_ops->fault(vma, &vmf);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
return ret;
if (ret & VM_FAULT_DAX_LOCKED) {
*entry = vmf.entry;
return ret;
}
if (unlikely(PageHWPoison(vmf.page))) {
if (ret & VM_FAULT_LOCKED)
unlock_page(vmf.page);
put_page(vmf.page);
return VM_FAULT_HWPOISON;
}
if (unlikely(!(ret & VM_FAULT_LOCKED)))
lock_page(vmf.page);
else
VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
*page = vmf.page;
return ret;
}
static int pte_alloc_one_map(struct fault_env *fe)
{
struct vm_area_struct *vma = fe->vma;
if (!pmd_none(*fe->pmd))
goto map_pte;
if (fe->prealloc_pte) {
fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
if (unlikely(!pmd_none(*fe->pmd))) {
spin_unlock(fe->ptl);
goto map_pte;
}
atomic_long_inc(&vma->vm_mm->nr_ptes);
pmd_populate(vma->vm_mm, fe->pmd, fe->prealloc_pte);
spin_unlock(fe->ptl);
fe->prealloc_pte = 0;
} else if (unlikely(pte_alloc(vma->vm_mm, fe->pmd, fe->address))) {
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.
*/
if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd))
return VM_FAULT_NOPAGE;
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
&fe->ptl);
return 0;
}
#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
#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;
}
static int do_set_pmd(struct fault_env *fe, struct page *page)
{
struct vm_area_struct *vma = fe->vma;
bool write = fe->flags & FAULT_FLAG_WRITE;
unsigned long haddr = fe->address & HPAGE_PMD_MASK;
pmd_t entry;
int i, ret;
if (!transhuge_vma_suitable(vma, haddr))
return VM_FAULT_FALLBACK;
ret = VM_FAULT_FALLBACK;
page = compound_head(page);
fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
if (unlikely(!pmd_none(*fe->pmd)))
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);
set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry);
update_mmu_cache_pmd(vma, haddr, fe->pmd);
/* fault is handled */
ret = 0;
count_vm_event(THP_FILE_MAPPED);
out:
spin_unlock(fe->ptl);
return ret;
}
#else
static int do_set_pmd(struct fault_env *fe, struct page *page)
{
BUILD_BUG();
return 0;
}
#endif
/**
* 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.
*
* @fe: fault environment
* @memcg: memcg to charge page (only for private mappings)
* @page: page to map
*
* Caller must take care of unlocking fe->ptl, if fe->pte is non-NULL on return.
*
* Target users are page handler itself and implementations of
* vm_ops->map_pages.
*/
int alloc_set_pte(struct fault_env *fe, struct mem_cgroup *memcg,
struct page *page)
{
struct vm_area_struct *vma = fe->vma;
bool write = fe->flags & FAULT_FLAG_WRITE;
pte_t entry;
int ret;
if (pmd_none(*fe->pmd) && PageTransCompound(page) &&
IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
/* THP on COW? */
VM_BUG_ON_PAGE(memcg, page);
ret = do_set_pmd(fe, page);
if (ret != VM_FAULT_FALLBACK)
return ret;
}
if (!fe->pte) {
ret = pte_alloc_one_map(fe);
if (ret)
return ret;
}
/* Re-check under ptl */
if (unlikely(!pte_none(*fe->pte)))
return VM_FAULT_NOPAGE;
flush_icache_page(vma, page);
entry = mk_pte(page, vma->vm_page_prot);
if (write)
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
/* copy-on-write page */
if (write && !(vma->vm_flags & VM_SHARED)) {
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
page_add_new_anon_rmap(page, vma, fe->address, false);
mem_cgroup_commit_charge(page, memcg, false, false);
lru_cache_add_active_or_unevictable(page, vma);
} else {
inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
page_add_file_rmap(page, false);
}
set_pte_at(vma->vm_mm, fe->address, fe->pte, entry);
/* no need to invalidate: a not-present page won't be cached */
update_mmu_cache(vma, fe->address, fe->pte);
return 0;
}
static unsigned long fault_around_bytes __read_mostly =
rounddown_pow_of_two(65536);
#ifdef CONFIG_DEBUG_FS
static int fault_around_bytes_get(void *data, u64 *val)
{
*val = fault_around_bytes;
return 0;
}
/*
* 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.
*/
static int fault_around_bytes_set(void *data, u64 val)
{
if (val / PAGE_SIZE > PTRS_PER_PTE)
return -EINVAL;
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 */
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
static int __init fault_around_debugfs(void)
{
void *ret;
ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
&fault_around_bytes_fops);
if (!ret)
pr_warn("Failed to create fault_around_bytes in debugfs");
return 0;
}
late_initcall(fault_around_debugfs);
#endif
/*
* 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.
*/
static int do_fault_around(struct fault_env *fe, pgoff_t start_pgoff)
{
unsigned long address = fe->address, nr_pages, mask;
pgoff_t end_pgoff;
int off, ret = 0;
nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
fe->address = max(address & mask, fe->vma->vm_start);
off = ((address - fe->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
start_pgoff -= off;
/*
* end_pgoff is either end of page table or end of vma
* or fault_around_pages() from start_pgoff, depending what is nearest.
*/
end_pgoff = start_pgoff -
((fe->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
PTRS_PER_PTE - 1;
end_pgoff = min3(end_pgoff, vma_pages(fe->vma) + fe->vma->vm_pgoff - 1,
start_pgoff + nr_pages - 1);
if (pmd_none(*fe->pmd)) {
fe->prealloc_pte = pte_alloc_one(fe->vma->vm_mm, fe->address);
if (!fe->prealloc_pte)
goto out;
smp_wmb(); /* See comment in __pte_alloc() */
}
fe->vma->vm_ops->map_pages(fe, start_pgoff, end_pgoff);
/* preallocated pagetable is unused: free it */
if (fe->prealloc_pte) {
pte_free(fe->vma->vm_mm, fe->prealloc_pte);
fe->prealloc_pte = 0;
}
/* Huge page is mapped? Page fault is solved */
if (pmd_trans_huge(*fe->pmd)) {
ret = VM_FAULT_NOPAGE;
goto out;
}
/* ->map_pages() haven't done anything useful. Cold page cache? */
if (!fe->pte)
goto out;
/* check if the page fault is solved */
fe->pte -= (fe->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
if (!pte_none(*fe->pte))
ret = VM_FAULT_NOPAGE;
pte_unmap_unlock(fe->pte, fe->ptl);
out:
fe->address = address;
fe->pte = NULL;
return ret;
}
static int do_read_fault(struct fault_env *fe, pgoff_t pgoff)
{
struct vm_area_struct *vma = fe->vma;
struct page *fault_page;
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).
*/
if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
ret = do_fault_around(fe, pgoff);
if (ret)
return ret;
}
ret = __do_fault(fe, pgoff, NULL, &fault_page, NULL);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
return ret;
ret |= alloc_set_pte(fe, NULL, fault_page);
if (fe->pte)
pte_unmap_unlock(fe->pte, fe->ptl);
unlock_page(fault_page);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
put_page(fault_page);
return ret;
}
static int do_cow_fault(struct fault_env *fe, pgoff_t pgoff)
{
struct vm_area_struct *vma = fe->vma;
struct page *fault_page, *new_page;
void *fault_entry;
struct mem_cgroup *memcg;
int ret;
if (unlikely(anon_vma_prepare(vma)))
return VM_FAULT_OOM;
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, fe->address);
if (!new_page)
return VM_FAULT_OOM;
if (mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL,
&memcg, false)) {
put_page(new_page);
return VM_FAULT_OOM;
}
ret = __do_fault(fe, pgoff, new_page, &fault_page, &fault_entry);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
goto uncharge_out;
if (!(ret & VM_FAULT_DAX_LOCKED))
copy_user_highpage(new_page, fault_page, fe->address, vma);
__SetPageUptodate(new_page);
ret |= alloc_set_pte(fe, memcg, new_page);
if (fe->pte)
pte_unmap_unlock(fe->pte, fe->ptl);
if (!(ret & VM_FAULT_DAX_LOCKED)) {
unlock_page(fault_page);
put_page(fault_page);
} else {
dax_unlock_mapping_entry(vma->vm_file->f_mapping, pgoff);
}
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
goto uncharge_out;
return ret;
uncharge_out:
mem_cgroup_cancel_charge(new_page, memcg, false);
put_page(new_page);
return ret;
}
static int do_shared_fault(struct fault_env *fe, pgoff_t pgoff)
{
struct vm_area_struct *vma = fe->vma;
struct page *fault_page;
struct address_space *mapping;
int dirtied = 0;
int ret, tmp;
ret = __do_fault(fe, pgoff, NULL, &fault_page, NULL);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
return ret;
/*
* Check if the backing address space wants to know that the page is
* about to become writable
*/
if (vma->vm_ops->page_mkwrite) {
unlock_page(fault_page);
tmp = do_page_mkwrite(vma, fault_page, fe->address);
if (unlikely(!tmp ||
(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
put_page(fault_page);
return tmp;
}
}
ret |= alloc_set_pte(fe, NULL, fault_page);
if (fe->pte)
pte_unmap_unlock(fe->pte, fe->ptl);
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
VM_FAULT_RETRY))) {
unlock_page(fault_page);
put_page(fault_page);
return ret;
}
if (set_page_dirty(fault_page))
dirtied = 1;
/*
* 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(fault_page);
unlock_page(fault_page);
if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
/*
* Some device drivers do not set page.mapping but still
* dirty their pages
*/
balance_dirty_pages_ratelimited(mapping);
}
if (!vma->vm_ops->page_mkwrite)
file_update_time(vma->vm_file);
return ret;
}
/*
* 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().
*/
static int do_fault(struct fault_env *fe)
{
struct vm_area_struct *vma = fe->vma;
pgoff_t pgoff = linear_page_index(vma, fe->address);
/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
if (!vma->vm_ops->fault)
return VM_FAULT_SIGBUS;
if (!(fe->flags & FAULT_FLAG_WRITE))
return do_read_fault(fe, pgoff);
if (!(vma->vm_flags & VM_SHARED))
return do_cow_fault(fe, pgoff);
return do_shared_fault(fe, pgoff);
}
static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
unsigned long addr, int page_nid,
int *flags)
{
get_page(page);
count_vm_numa_event(NUMA_HINT_FAULTS);
if (page_nid == numa_node_id()) {
count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
*flags |= TNF_FAULT_LOCAL;
}
return mpol_misplaced(page, vma, addr);
}
static int do_numa_page(struct fault_env *fe, pte_t pte)
{
struct vm_area_struct *vma = fe->vma;
struct page *page = NULL;
int page_nid = -1;
int last_cpupid;
int target_nid;
bool migrated = false;
bool was_writable = pte_write(pte);
int flags = 0;
/* A PROT_NONE fault should not end up here */
BUG_ON(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)));
/*
* 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.
*
* We can safely just do a "set_pte_at()", because the old
* page table entry is not accessible, so there would be no
* concurrent hardware modifications to the PTE.
*/
fe->ptl = pte_lockptr(vma->vm_mm, fe->pmd);
spin_lock(fe->ptl);
if (unlikely(!pte_same(*fe->pte, pte))) {
pte_unmap_unlock(fe->pte, fe->ptl);
goto out;
}
/* Make it present again */
pte = pte_modify(pte, vma->vm_page_prot);
pte = pte_mkyoung(pte);
if (was_writable)
pte = pte_mkwrite(pte);
set_pte_at(vma->vm_mm, fe->address, fe->pte, pte);
update_mmu_cache(vma, fe->address, fe->pte);
page = vm_normal_page(vma, fe->address, pte);
if (!page) {
pte_unmap_unlock(fe->pte, fe->ptl);
return 0;
}
/* TODO: handle PTE-mapped THP */
if (PageCompound(page)) {
pte_unmap_unlock(fe->pte, fe->ptl);
return 0;
}
/*
* 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.
*/
if (!(vma->vm_flags & VM_WRITE))
flags |= TNF_NO_GROUP;
/*
* 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;
last_cpupid = page_cpupid_last(page);
page_nid = page_to_nid(page);
target_nid = numa_migrate_prep(page, vma, fe->address, page_nid,
&flags);
pte_unmap_unlock(fe->pte, fe->ptl);
if (target_nid == -1) {
put_page(page);
goto out;
}
/* Migrate to the requested node */
migrated = migrate_misplaced_page(page, vma, target_nid);
if (migrated) {
page_nid = target_nid;
flags |= TNF_MIGRATED;
} else
flags |= TNF_MIGRATE_FAIL;
out:
if (page_nid != -1)
task_numa_fault(last_cpupid, page_nid, 1, flags);
return 0;
}
static int create_huge_pmd(struct fault_env *fe)
{
struct vm_area_struct *vma = fe->vma;
if (vma_is_anonymous(vma))
return do_huge_pmd_anonymous_page(fe);
if (vma->vm_ops->pmd_fault)
return vma->vm_ops->pmd_fault(vma, fe->address, fe->pmd,
fe->flags);
return VM_FAULT_FALLBACK;
}
static int wp_huge_pmd(struct fault_env *fe, pmd_t orig_pmd)
{
if (vma_is_anonymous(fe->vma))
return do_huge_pmd_wp_page(fe, orig_pmd);
if (fe->vma->vm_ops->pmd_fault)
return fe->vma->vm_ops->pmd_fault(fe->vma, fe->address, fe->pmd,
fe->flags);
/* COW handled on pte level: split pmd */
VM_BUG_ON_VMA(fe->vma->vm_flags & VM_SHARED, fe->vma);
split_huge_pmd(fe->vma, fe->pmd, fe->address);
return VM_FAULT_FALLBACK;
}
/*
* 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).
*
* 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().
*/
static int handle_pte_fault(struct fault_env *fe)
{
pte_t entry;
if (unlikely(pmd_none(*fe->pmd))) {
/*
* 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.
*/
fe->pte = NULL;
} else {
/* See comment in pte_alloc_one_map() */
if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd))
return 0;
/*
* A regular pmd is established and it can't morph into a huge
* pmd from under us anymore at this point because we hold the
* mmap_sem read mode and khugepaged takes it in write mode.
* So now it's safe to run pte_offset_map().
*/
fe->pte = pte_offset_map(fe->pmd, fe->address);
entry = *fe->pte;
/*
* 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();
if (pte_none(entry)) {
pte_unmap(fe->pte);
fe->pte = NULL;
}
}
if (!fe->pte) {
if (vma_is_anonymous(fe->vma))
return do_anonymous_page(fe);
else
return do_fault(fe);
}
if (!pte_present(entry))
return do_swap_page(fe, entry);
if (pte_protnone(entry))
return do_numa_page(fe, entry);
fe->ptl = pte_lockptr(fe->vma->vm_mm, fe->pmd);
spin_lock(fe->ptl);
if (unlikely(!pte_same(*fe->pte, entry)))
goto unlock;
if (fe->flags & FAULT_FLAG_WRITE) {
if (!pte_write(entry))
return do_wp_page(fe, entry);
entry = pte_mkdirty(entry);
}
entry = pte_mkyoung(entry);
if (ptep_set_access_flags(fe->vma, fe->address, fe->pte, entry,
fe->flags & FAULT_FLAG_WRITE)) {
update_mmu_cache(fe->vma, fe->address, fe->pte);
} 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.
*/
if (fe->flags & FAULT_FLAG_WRITE)
flush_tlb_fix_spurious_fault(fe->vma, fe->address);
}
unlock:
pte_unmap_unlock(fe->pte, fe->ptl);
return 0;
}
/*
* 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().
*/
static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
unsigned int flags)
{
struct fault_env fe = {
.vma = vma,
.address = address,
.flags = flags,
};
struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
pud_t *pud;
pgd = pgd_offset(mm, address);
pud = pud_alloc(mm, pgd, address);
if (!pud)
return VM_FAULT_OOM;
fe.pmd = pmd_alloc(mm, pud, address);
if (!fe.pmd)
return VM_FAULT_OOM;
if (pmd_none(*fe.pmd) && transparent_hugepage_enabled(vma)) {
int ret = create_huge_pmd(&fe);
if (!(ret & VM_FAULT_FALLBACK))
return ret;
} else {
pmd_t orig_pmd = *fe.pmd;
int ret;
barrier();
if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
if (pmd_protnone(orig_pmd))
return do_huge_pmd_numa_page(&fe, orig_pmd);
if ((fe.flags & FAULT_FLAG_WRITE) &&
!pmd_write(orig_pmd)) {
ret = wp_huge_pmd(&fe, orig_pmd);
if (!(ret & VM_FAULT_FALLBACK))
return ret;
} else {
huge_pmd_set_accessed(&fe, orig_pmd);
return 0;
}
}
}
return handle_pte_fault(&fe);
}
/*
* 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().
*/
int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
unsigned int flags)
{
int ret;
__set_current_state(TASK_RUNNING);
count_vm_event(PGFAULT);
mem_cgroup_count_vm_event(vma->vm_mm, PGFAULT);
/* do counter updates before entering really critical section. */
check_sync_rss_stat(current);
/*
* Enable the memcg OOM handling for faults triggered in user
* space. Kernel faults are handled more gracefully.
*/
if (flags & FAULT_FLAG_USER)
mem_cgroup_oom_enable();
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);
if (flags & FAULT_FLAG_USER) {
mem_cgroup_oom_disable();
/*
* The task may have entered a memcg OOM situation but
* if the allocation error was handled gracefully (no
* VM_FAULT_OOM), there is no need to kill anything.
* Just clean up the OOM state peacefully.
*/
if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
mem_cgroup_oom_synchronize(false);
}
return ret;
}
EXPORT_SYMBOL_GPL(handle_mm_fault);
#ifndef __PAGETABLE_PUD_FOLDED
/*
* Allocate page upper directory.
* We've already handled the fast-path in-line.
*/
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
{
pud_t *new = pud_alloc_one(mm, address);
if (!new)
return -ENOMEM;
smp_wmb(); /* See comment in __pte_alloc */
spin_lock(&mm->page_table_lock);
if (pgd_present(*pgd)) /* Another has populated it */
pud_free(mm, new);
else
pgd_populate(mm, pgd, new);
spin_unlock(&mm->page_table_lock);
return 0;
}
#endif /* __PAGETABLE_PUD_FOLDED */
#ifndef __PAGETABLE_PMD_FOLDED
/*
* Allocate page middle directory.
* We've already handled the fast-path in-line.
*/
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
{
pmd_t *new = pmd_alloc_one(mm, address);
if (!new)
return -ENOMEM;
smp_wmb(); /* See comment in __pte_alloc */
spin_lock(&mm->page_table_lock);
#ifndef __ARCH_HAS_4LEVEL_HACK
if (!pud_present(*pud)) {
mm_inc_nr_pmds(mm);
pud_populate(mm, pud, new);
} else /* Another has populated it */
pmd_free(mm, new);
#else
if (!pgd_present(*pud)) {
mm_inc_nr_pmds(mm);
pgd_populate(mm, pud, new);
} else /* Another has populated it */
pmd_free(mm, new);
#endif /* __ARCH_HAS_4LEVEL_HACK */
spin_unlock(&mm->page_table_lock);
return 0;
}
#endif /* __PAGETABLE_PMD_FOLDED */
static int __follow_pte(struct mm_struct *mm, unsigned long address,
pte_t **ptepp, spinlock_t **ptlp)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *ptep;
pgd = pgd_offset(mm, address);
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
goto out;
pud = pud_offset(pgd, address);
if (pud_none(*pud) || unlikely(pud_bad(*pud)))
goto out;
pmd = pmd_offset(pud, address);
VM_BUG_ON(pmd_trans_huge(*pmd));
if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
goto out;
/* We cannot handle huge page PFN maps. Luckily they don't exist. */
if (pmd_huge(*pmd))
goto out;
ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
if (!ptep)
goto out;
if (!pte_present(*ptep))
goto unlock;
*ptepp = ptep;
return 0;
unlock:
pte_unmap_unlock(ptep, *ptlp);
out:
return -EINVAL;
}
static inline int follow_pte(struct mm_struct *mm, unsigned long address,
pte_t **ptepp, spinlock_t **ptlp)
{
int res;
/* (void) is needed to make gcc happy */
(void) __cond_lock(*ptlp,
!(res = __follow_pte(mm, address, ptepp, ptlp)));
return res;
}
/**
* 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);
#ifdef CONFIG_HAVE_IOREMAP_PROT
int follow_phys(struct vm_area_struct *vma,
unsigned long address, unsigned int flags,
unsigned long *prot, resource_size_t *phys)
{
int ret = -EINVAL;
pte_t *ptep, pte;
spinlock_t *ptl;
if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
goto out;
if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
goto out;
pte = *ptep;
if ((flags & FOLL_WRITE) && !pte_write(pte))
goto unlock;
*prot = pgprot_val(pte_pgprot(pte));
*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
ret = 0;
unlock:
pte_unmap_unlock(ptep, ptl);
out:
return ret;
}
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;
void __iomem *maddr;
int offset = addr & (PAGE_SIZE-1);
if (follow_phys(vma, addr, write, &prot, &phys_addr))
return -EINVAL;
maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
if (write)
memcpy_toio(maddr + offset, buf, len);
else
memcpy_fromio(buf, maddr + offset, len);
iounmap(maddr);
return len;
}
EXPORT_SYMBOL_GPL(generic_access_phys);
#endif
/*
* Access another process' address space as given in mm. If non-NULL, use the
* given task for page fault accounting.
*/
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
unsigned long addr, void *buf, int len, int write)
{
struct vm_area_struct *vma;
void *old_buf = buf;
down_read(&mm->mmap_sem);
/* ignore errors, just check how much was successfully transferred */
while (len) {
int bytes, ret, offset;
void *maddr;
struct page *page = NULL;
ret = get_user_pages_remote(tsk, mm, addr, 1,
write, 1, &page, &vma);
if (ret <= 0) {
#ifndef CONFIG_HAVE_IOREMAP_PROT
break;
#else
/*
* Check if this is a VM_IO | VM_PFNMAP VMA, which
* we can access using slightly different code.
*/
vma = find_vma(mm, addr);
if (!vma || vma->vm_start > addr)
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;
#endif
} else {
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);
put_page(page);
}
len -= bytes;
buf += bytes;
addr += bytes;
}
up_read(&mm->mmap_sem);
return buf - old_buf;
}
/**
* access_remote_vm - access another process' address space
* @mm: the mm_struct of the target address space
* @addr: start address to access
* @buf: source or destination buffer
* @len: number of bytes to transfer
* @write: whether the access is a write
*
* The caller must hold a reference on @mm.
*/
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
void *buf, int len, int write)
{
return __access_remote_vm(NULL, mm, addr, buf, len, write);
}
/*
* Access another process' address space.
* Source/target buffer must be kernel space,
* Do not walk the page table directly, use get_user_pages
*/
int access_process_vm(struct task_struct *tsk, unsigned long addr,
void *buf, int len, int write)
{
struct mm_struct *mm;
int ret;
mm = get_task_mm(tsk);
if (!mm)
return 0;
ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
mmput(mm);
return ret;
}
/*
* 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;
/*
* Do not print if we are in atomic
* contexts (in exception stacks, etc.):
*/
if (preempt_count())
return;
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) {
char *p;
p = file_path(f, buf, PAGE_SIZE);
if (IS_ERR(p))
p = "?";
printk("%s%s[%lx+%lx]", prefix, kbasename(p),
vma->vm_start,
vma->vm_end - vma->vm_start);
free_page((unsigned long)buf);
}
}
up_read(&mm->mmap_sem);
}
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
void __might_fault(const char *file, int line)
{
/*
* 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;
if (pagefault_disabled())
return;
__might_sleep(file, line, 0);
#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
if (current->mm)
might_lock_read(&current->mm->mmap_sem);
#endif
}
EXPORT_SYMBOL(__might_fault);
#endif
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
static void clear_gigantic_page(struct page *page,
unsigned long addr,
unsigned int pages_per_huge_page)
{
int i;
struct page *p = page;
might_sleep();
for (i = 0; i < pages_per_huge_page;
i++, p = mem_map_next(p, page, i)) {
cond_resched();
clear_user_highpage(p, addr + i * PAGE_SIZE);
}
}
void clear_huge_page(struct page *page,
unsigned long addr, unsigned int pages_per_huge_page)
{
int i;
if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
clear_gigantic_page(page, addr, pages_per_huge_page);
return;
}
might_sleep();
for (i = 0; i < pages_per_huge_page; i++) {
cond_resched();
clear_user_highpage(page + i, addr + i * PAGE_SIZE);
}
}
static void copy_user_gigantic_page(struct page *dst, struct page *src,
unsigned long addr,
struct vm_area_struct *vma,
unsigned int pages_per_huge_page)
{
int i;
struct page *dst_base = dst;
struct page *src_base = src;
for (i = 0; i < pages_per_huge_page; ) {
cond_resched();
copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
i++;
dst = mem_map_next(dst, dst_base, i);
src = mem_map_next(src, src_base, i);
}
}
void copy_user_huge_page(struct page *dst, struct page *src,
unsigned long addr, struct vm_area_struct *vma,
unsigned int pages_per_huge_page)
{
int i;
if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
copy_user_gigantic_page(dst, src, addr, vma,
pages_per_huge_page);
return;
}
might_sleep();
for (i = 0; i < pages_per_huge_page; i++) {
cond_resched();
copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
}
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
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);
}
bool ptlock_alloc(struct page *page)
{
spinlock_t *ptl;
ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
if (!ptl)
return false;
page->ptl = ptl;
return true;
}
void ptlock_free(struct page *page)
{
kmem_cache_free(page_ptl_cachep, page->ptl);
}
#endif