blob: 96178f4c1215c4ba4f16ec696fa77f20568b004c [file] [log] [blame]
/*
* Memory Migration functionality - linux/mm/migration.c
*
* Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
*
* Page migration was first developed in the context of the memory hotplug
* project. The main authors of the migration code are:
*
* IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
* Hirokazu Takahashi <taka@valinux.co.jp>
* Dave Hansen <haveblue@us.ibm.com>
* Christoph Lameter
*/
#include <linux/migrate.h>
#include <linux/module.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include <linux/mm_inline.h>
#include <linux/nsproxy.h>
#include <linux/pagevec.h>
#include <linux/rmap.h>
#include <linux/topology.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/writeback.h>
#include <linux/mempolicy.h>
#include <linux/vmalloc.h>
#include <linux/security.h>
#include <linux/memcontrol.h>
#include <linux/syscalls.h>
#include "internal.h"
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
/*
* Isolate one page from the LRU lists. If successful put it onto
* the indicated list with elevated page count.
*
* Result:
* -EBUSY: page not on LRU list
* 0: page removed from LRU list and added to the specified list.
*/
int isolate_lru_page(struct page *page, struct list_head *pagelist)
{
int ret = -EBUSY;
if (PageLRU(page)) {
struct zone *zone = page_zone(page);
spin_lock_irq(&zone->lru_lock);
if (PageLRU(page) && get_page_unless_zero(page)) {
ret = 0;
ClearPageLRU(page);
if (PageActive(page))
del_page_from_active_list(zone, page);
else
del_page_from_inactive_list(zone, page);
list_add_tail(&page->lru, pagelist);
}
spin_unlock_irq(&zone->lru_lock);
}
return ret;
}
/*
* migrate_prep() needs to be called before we start compiling a list of pages
* to be migrated using isolate_lru_page().
*/
int migrate_prep(void)
{
/*
* Clear the LRU lists so pages can be isolated.
* Note that pages may be moved off the LRU after we have
* drained them. Those pages will fail to migrate like other
* pages that may be busy.
*/
lru_add_drain_all();
return 0;
}
static inline void move_to_lru(struct page *page)
{
if (PageActive(page)) {
/*
* lru_cache_add_active checks that
* the PG_active bit is off.
*/
ClearPageActive(page);
lru_cache_add_active(page);
} else {
lru_cache_add(page);
}
put_page(page);
}
/*
* Add isolated pages on the list back to the LRU.
*
* returns the number of pages put back.
*/
int putback_lru_pages(struct list_head *l)
{
struct page *page;
struct page *page2;
int count = 0;
list_for_each_entry_safe(page, page2, l, lru) {
list_del(&page->lru);
move_to_lru(page);
count++;
}
return count;
}
/*
* Restore a potential migration pte to a working pte entry
*/
static void remove_migration_pte(struct vm_area_struct *vma,
struct page *old, struct page *new)
{
struct mm_struct *mm = vma->vm_mm;
swp_entry_t entry;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *ptep, pte;
spinlock_t *ptl;
unsigned long addr = page_address_in_vma(new, vma);
if (addr == -EFAULT)
return;
pgd = pgd_offset(mm, addr);
if (!pgd_present(*pgd))
return;
pud = pud_offset(pgd, addr);
if (!pud_present(*pud))
return;
pmd = pmd_offset(pud, addr);
if (!pmd_present(*pmd))
return;
ptep = pte_offset_map(pmd, addr);
if (!is_swap_pte(*ptep)) {
pte_unmap(ptep);
return;
}
ptl = pte_lockptr(mm, pmd);
spin_lock(ptl);
pte = *ptep;
if (!is_swap_pte(pte))
goto out;
entry = pte_to_swp_entry(pte);
if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
goto out;
/*
* Yes, ignore the return value from a GFP_ATOMIC mem_cgroup_charge.
* Failure is not an option here: we're now expected to remove every
* migration pte, and will cause crashes otherwise. Normally this
* is not an issue: mem_cgroup_prepare_migration bumped up the old
* page_cgroup count for safety, that's now attached to the new page,
* so this charge should just be another incrementation of the count,
* to keep in balance with rmap.c's mem_cgroup_uncharging. But if
* there's been a force_empty, those reference counts may no longer
* be reliable, and this charge can actually fail: oh well, we don't
* make the situation any worse by proceeding as if it had succeeded.
*/
mem_cgroup_charge(new, mm, GFP_ATOMIC);
get_page(new);
pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
if (is_write_migration_entry(entry))
pte = pte_mkwrite(pte);
flush_cache_page(vma, addr, pte_pfn(pte));
set_pte_at(mm, addr, ptep, pte);
if (PageAnon(new))
page_add_anon_rmap(new, vma, addr);
else
page_add_file_rmap(new);
/* No need to invalidate - it was non-present before */
update_mmu_cache(vma, addr, pte);
out:
pte_unmap_unlock(ptep, ptl);
}
/*
* Note that remove_file_migration_ptes will only work on regular mappings,
* Nonlinear mappings do not use migration entries.
*/
static void remove_file_migration_ptes(struct page *old, struct page *new)
{
struct vm_area_struct *vma;
struct address_space *mapping = page_mapping(new);
struct prio_tree_iter iter;
pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
if (!mapping)
return;
spin_lock(&mapping->i_mmap_lock);
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
remove_migration_pte(vma, old, new);
spin_unlock(&mapping->i_mmap_lock);
}
/*
* Must hold mmap_sem lock on at least one of the vmas containing
* the page so that the anon_vma cannot vanish.
*/
static void remove_anon_migration_ptes(struct page *old, struct page *new)
{
struct anon_vma *anon_vma;
struct vm_area_struct *vma;
unsigned long mapping;
mapping = (unsigned long)new->mapping;
if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
return;
/*
* We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
*/
anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
spin_lock(&anon_vma->lock);
list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
remove_migration_pte(vma, old, new);
spin_unlock(&anon_vma->lock);
}
/*
* Get rid of all migration entries and replace them by
* references to the indicated page.
*/
static void remove_migration_ptes(struct page *old, struct page *new)
{
if (PageAnon(new))
remove_anon_migration_ptes(old, new);
else
remove_file_migration_ptes(old, new);
}
/*
* Something used the pte of a page under migration. We need to
* get to the page and wait until migration is finished.
* When we return from this function the fault will be retried.
*
* This function is called from do_swap_page().
*/
void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
unsigned long address)
{
pte_t *ptep, pte;
spinlock_t *ptl;
swp_entry_t entry;
struct page *page;
ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
pte = *ptep;
if (!is_swap_pte(pte))
goto out;
entry = pte_to_swp_entry(pte);
if (!is_migration_entry(entry))
goto out;
page = migration_entry_to_page(entry);
/*
* Once radix-tree replacement of page migration started, page_count
* *must* be zero. And, we don't want to call wait_on_page_locked()
* against a page without get_page().
* So, we use get_page_unless_zero(), here. Even failed, page fault
* will occur again.
*/
if (!get_page_unless_zero(page))
goto out;
pte_unmap_unlock(ptep, ptl);
wait_on_page_locked(page);
put_page(page);
return;
out:
pte_unmap_unlock(ptep, ptl);
}
/*
* Replace the page in the mapping.
*
* The number of remaining references must be:
* 1 for anonymous pages without a mapping
* 2 for pages with a mapping
* 3 for pages with a mapping and PagePrivate set.
*/
static int migrate_page_move_mapping(struct address_space *mapping,
struct page *newpage, struct page *page)
{
int expected_count;
void **pslot;
if (!mapping) {
/* Anonymous page without mapping */
if (page_count(page) != 1)
return -EAGAIN;
return 0;
}
spin_lock_irq(&mapping->tree_lock);
pslot = radix_tree_lookup_slot(&mapping->page_tree,
page_index(page));
expected_count = 2 + !!PagePrivate(page);
if (page_count(page) != expected_count ||
(struct page *)radix_tree_deref_slot(pslot) != page) {
spin_unlock_irq(&mapping->tree_lock);
return -EAGAIN;
}
if (!page_freeze_refs(page, expected_count)) {
spin_unlock_irq(&mapping->tree_lock);
return -EAGAIN;
}
/*
* Now we know that no one else is looking at the page.
*/
get_page(newpage); /* add cache reference */
#ifdef CONFIG_SWAP
if (PageSwapCache(page)) {
SetPageSwapCache(newpage);
set_page_private(newpage, page_private(page));
}
#endif
radix_tree_replace_slot(pslot, newpage);
page_unfreeze_refs(page, expected_count);
/*
* Drop cache reference from old page.
* We know this isn't the last reference.
*/
__put_page(page);
/*
* If moved to a different zone then also account
* the page for that zone. Other VM counters will be
* taken care of when we establish references to the
* new page and drop references to the old page.
*
* Note that anonymous pages are accounted for
* via NR_FILE_PAGES and NR_ANON_PAGES if they
* are mapped to swap space.
*/
__dec_zone_page_state(page, NR_FILE_PAGES);
__inc_zone_page_state(newpage, NR_FILE_PAGES);
spin_unlock_irq(&mapping->tree_lock);
if (!PageSwapCache(newpage))
mem_cgroup_uncharge_cache_page(page);
return 0;
}
/*
* Copy the page to its new location
*/
static void migrate_page_copy(struct page *newpage, struct page *page)
{
copy_highpage(newpage, page);
if (PageError(page))
SetPageError(newpage);
if (PageReferenced(page))
SetPageReferenced(newpage);
if (PageUptodate(page))
SetPageUptodate(newpage);
if (PageActive(page))
SetPageActive(newpage);
if (PageChecked(page))
SetPageChecked(newpage);
if (PageMappedToDisk(page))
SetPageMappedToDisk(newpage);
if (PageDirty(page)) {
clear_page_dirty_for_io(page);
/*
* Want to mark the page and the radix tree as dirty, and
* redo the accounting that clear_page_dirty_for_io undid,
* but we can't use set_page_dirty because that function
* is actually a signal that all of the page has become dirty.
* Wheras only part of our page may be dirty.
*/
__set_page_dirty_nobuffers(newpage);
}
#ifdef CONFIG_SWAP
ClearPageSwapCache(page);
#endif
ClearPageActive(page);
ClearPagePrivate(page);
set_page_private(page, 0);
page->mapping = NULL;
/*
* If any waiters have accumulated on the new page then
* wake them up.
*/
if (PageWriteback(newpage))
end_page_writeback(newpage);
}
/************************************************************
* Migration functions
***********************************************************/
/* Always fail migration. Used for mappings that are not movable */
int fail_migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page)
{
return -EIO;
}
EXPORT_SYMBOL(fail_migrate_page);
/*
* Common logic to directly migrate a single page suitable for
* pages that do not use PagePrivate.
*
* Pages are locked upon entry and exit.
*/
int migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page)
{
int rc;
BUG_ON(PageWriteback(page)); /* Writeback must be complete */
rc = migrate_page_move_mapping(mapping, newpage, page);
if (rc)
return rc;
migrate_page_copy(newpage, page);
return 0;
}
EXPORT_SYMBOL(migrate_page);
#ifdef CONFIG_BLOCK
/*
* Migration function for pages with buffers. This function can only be used
* if the underlying filesystem guarantees that no other references to "page"
* exist.
*/
int buffer_migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page)
{
struct buffer_head *bh, *head;
int rc;
if (!page_has_buffers(page))
return migrate_page(mapping, newpage, page);
head = page_buffers(page);
rc = migrate_page_move_mapping(mapping, newpage, page);
if (rc)
return rc;
bh = head;
do {
get_bh(bh);
lock_buffer(bh);
bh = bh->b_this_page;
} while (bh != head);
ClearPagePrivate(page);
set_page_private(newpage, page_private(page));
set_page_private(page, 0);
put_page(page);
get_page(newpage);
bh = head;
do {
set_bh_page(bh, newpage, bh_offset(bh));
bh = bh->b_this_page;
} while (bh != head);
SetPagePrivate(newpage);
migrate_page_copy(newpage, page);
bh = head;
do {
unlock_buffer(bh);
put_bh(bh);
bh = bh->b_this_page;
} while (bh != head);
return 0;
}
EXPORT_SYMBOL(buffer_migrate_page);
#endif
/*
* Writeback a page to clean the dirty state
*/
static int writeout(struct address_space *mapping, struct page *page)
{
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
.nr_to_write = 1,
.range_start = 0,
.range_end = LLONG_MAX,
.nonblocking = 1,
.for_reclaim = 1
};
int rc;
if (!mapping->a_ops->writepage)
/* No write method for the address space */
return -EINVAL;
if (!clear_page_dirty_for_io(page))
/* Someone else already triggered a write */
return -EAGAIN;
/*
* A dirty page may imply that the underlying filesystem has
* the page on some queue. So the page must be clean for
* migration. Writeout may mean we loose the lock and the
* page state is no longer what we checked for earlier.
* At this point we know that the migration attempt cannot
* be successful.
*/
remove_migration_ptes(page, page);
rc = mapping->a_ops->writepage(page, &wbc);
if (rc < 0)
/* I/O Error writing */
return -EIO;
if (rc != AOP_WRITEPAGE_ACTIVATE)
/* unlocked. Relock */
lock_page(page);
return -EAGAIN;
}
/*
* Default handling if a filesystem does not provide a migration function.
*/
static int fallback_migrate_page(struct address_space *mapping,
struct page *newpage, struct page *page)
{
if (PageDirty(page))
return writeout(mapping, page);
/*
* Buffers may be managed in a filesystem specific way.
* We must have no buffers or drop them.
*/
if (PagePrivate(page) &&
!try_to_release_page(page, GFP_KERNEL))
return -EAGAIN;
return migrate_page(mapping, newpage, page);
}
/*
* Move a page to a newly allocated page
* The page is locked and all ptes have been successfully removed.
*
* The new page will have replaced the old page if this function
* is successful.
*/
static int move_to_new_page(struct page *newpage, struct page *page)
{
struct address_space *mapping;
int rc;
/*
* Block others from accessing the page when we get around to
* establishing additional references. We are the only one
* holding a reference to the new page at this point.
*/
if (!trylock_page(newpage))
BUG();
/* Prepare mapping for the new page.*/
newpage->index = page->index;
newpage->mapping = page->mapping;
mapping = page_mapping(page);
if (!mapping)
rc = migrate_page(mapping, newpage, page);
else if (mapping->a_ops->migratepage)
/*
* Most pages have a mapping and most filesystems
* should provide a migration function. Anonymous
* pages are part of swap space which also has its
* own migration function. This is the most common
* path for page migration.
*/
rc = mapping->a_ops->migratepage(mapping,
newpage, page);
else
rc = fallback_migrate_page(mapping, newpage, page);
if (!rc) {
remove_migration_ptes(page, newpage);
} else
newpage->mapping = NULL;
unlock_page(newpage);
return rc;
}
/*
* Obtain the lock on page, remove all ptes and migrate the page
* to the newly allocated page in newpage.
*/
static int unmap_and_move(new_page_t get_new_page, unsigned long private,
struct page *page, int force)
{
int rc = 0;
int *result = NULL;
struct page *newpage = get_new_page(page, private, &result);
int rcu_locked = 0;
int charge = 0;
if (!newpage)
return -ENOMEM;
if (page_count(page) == 1)
/* page was freed from under us. So we are done. */
goto move_newpage;
charge = mem_cgroup_prepare_migration(page, newpage);
if (charge == -ENOMEM) {
rc = -ENOMEM;
goto move_newpage;
}
/* prepare cgroup just returns 0 or -ENOMEM */
BUG_ON(charge);
rc = -EAGAIN;
if (!trylock_page(page)) {
if (!force)
goto move_newpage;
lock_page(page);
}
if (PageWriteback(page)) {
if (!force)
goto unlock;
wait_on_page_writeback(page);
}
/*
* By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
* we cannot notice that anon_vma is freed while we migrates a page.
* This rcu_read_lock() delays freeing anon_vma pointer until the end
* of migration. File cache pages are no problem because of page_lock()
* File Caches may use write_page() or lock_page() in migration, then,
* just care Anon page here.
*/
if (PageAnon(page)) {
rcu_read_lock();
rcu_locked = 1;
}
/*
* Corner case handling:
* 1. When a new swap-cache page is read into, it is added to the LRU
* and treated as swapcache but it has no rmap yet.
* Calling try_to_unmap() against a page->mapping==NULL page will
* trigger a BUG. So handle it here.
* 2. An orphaned page (see truncate_complete_page) might have
* fs-private metadata. The page can be picked up due to memory
* offlining. Everywhere else except page reclaim, the page is
* invisible to the vm, so the page can not be migrated. So try to
* free the metadata, so the page can be freed.
*/
if (!page->mapping) {
if (!PageAnon(page) && PagePrivate(page)) {
/*
* Go direct to try_to_free_buffers() here because
* a) that's what try_to_release_page() would do anyway
* b) we may be under rcu_read_lock() here, so we can't
* use GFP_KERNEL which is what try_to_release_page()
* needs to be effective.
*/
try_to_free_buffers(page);
}
goto rcu_unlock;
}
/* Establish migration ptes or remove ptes */
try_to_unmap(page, 1);
if (!page_mapped(page))
rc = move_to_new_page(newpage, page);
if (rc)
remove_migration_ptes(page, page);
rcu_unlock:
if (rcu_locked)
rcu_read_unlock();
unlock:
unlock_page(page);
if (rc != -EAGAIN) {
/*
* A page that has been migrated has all references
* removed and will be freed. A page that has not been
* migrated will have kepts its references and be
* restored.
*/
list_del(&page->lru);
move_to_lru(page);
}
move_newpage:
if (!charge)
mem_cgroup_end_migration(newpage);
/*
* Move the new page to the LRU. If migration was not successful
* then this will free the page.
*/
move_to_lru(newpage);
if (result) {
if (rc)
*result = rc;
else
*result = page_to_nid(newpage);
}
return rc;
}
/*
* migrate_pages
*
* The function takes one list of pages to migrate and a function
* that determines from the page to be migrated and the private data
* the target of the move and allocates the page.
*
* The function returns after 10 attempts or if no pages
* are movable anymore because to has become empty
* or no retryable pages exist anymore. All pages will be
* returned to the LRU or freed.
*
* Return: Number of pages not migrated or error code.
*/
int migrate_pages(struct list_head *from,
new_page_t get_new_page, unsigned long private)
{
int retry = 1;
int nr_failed = 0;
int pass = 0;
struct page *page;
struct page *page2;
int swapwrite = current->flags & PF_SWAPWRITE;
int rc;
if (!swapwrite)
current->flags |= PF_SWAPWRITE;
for(pass = 0; pass < 10 && retry; pass++) {
retry = 0;
list_for_each_entry_safe(page, page2, from, lru) {
cond_resched();
rc = unmap_and_move(get_new_page, private,
page, pass > 2);
switch(rc) {
case -ENOMEM:
goto out;
case -EAGAIN:
retry++;
break;
case 0:
break;
default:
/* Permanent failure */
nr_failed++;
break;
}
}
}
rc = 0;
out:
if (!swapwrite)
current->flags &= ~PF_SWAPWRITE;
putback_lru_pages(from);
if (rc)
return rc;
return nr_failed + retry;
}
#ifdef CONFIG_NUMA
/*
* Move a list of individual pages
*/
struct page_to_node {
unsigned long addr;
struct page *page;
int node;
int status;
};
static struct page *new_page_node(struct page *p, unsigned long private,
int **result)
{
struct page_to_node *pm = (struct page_to_node *)private;
while (pm->node != MAX_NUMNODES && pm->page != p)
pm++;
if (pm->node == MAX_NUMNODES)
return NULL;
*result = &pm->status;
return alloc_pages_node(pm->node,
GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
}
/*
* Move a set of pages as indicated in the pm array. The addr
* field must be set to the virtual address of the page to be moved
* and the node number must contain a valid target node.
*/
static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
int migrate_all)
{
int err;
struct page_to_node *pp;
LIST_HEAD(pagelist);
down_read(&mm->mmap_sem);
/*
* Build a list of pages to migrate
*/
migrate_prep();
for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
struct vm_area_struct *vma;
struct page *page;
/*
* A valid page pointer that will not match any of the
* pages that will be moved.
*/
pp->page = ZERO_PAGE(0);
err = -EFAULT;
vma = find_vma(mm, pp->addr);
if (!vma || !vma_migratable(vma))
goto set_status;
page = follow_page(vma, pp->addr, FOLL_GET);
err = PTR_ERR(page);
if (IS_ERR(page))
goto set_status;
err = -ENOENT;
if (!page)
goto set_status;
if (PageReserved(page)) /* Check for zero page */
goto put_and_set;
pp->page = page;
err = page_to_nid(page);
if (err == pp->node)
/*
* Node already in the right place
*/
goto put_and_set;
err = -EACCES;
if (page_mapcount(page) > 1 &&
!migrate_all)
goto put_and_set;
err = isolate_lru_page(page, &pagelist);
put_and_set:
/*
* Either remove the duplicate refcount from
* isolate_lru_page() or drop the page ref if it was
* not isolated.
*/
put_page(page);
set_status:
pp->status = err;
}
if (!list_empty(&pagelist))
err = migrate_pages(&pagelist, new_page_node,
(unsigned long)pm);
else
err = -ENOENT;
up_read(&mm->mmap_sem);
return err;
}
/*
* Determine the nodes of a list of pages. The addr in the pm array
* must have been set to the virtual address of which we want to determine
* the node number.
*/
static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
{
down_read(&mm->mmap_sem);
for ( ; pm->node != MAX_NUMNODES; pm++) {
struct vm_area_struct *vma;
struct page *page;
int err;
err = -EFAULT;
vma = find_vma(mm, pm->addr);
if (!vma)
goto set_status;
page = follow_page(vma, pm->addr, 0);
err = PTR_ERR(page);
if (IS_ERR(page))
goto set_status;
err = -ENOENT;
/* Use PageReserved to check for zero page */
if (!page || PageReserved(page))
goto set_status;
err = page_to_nid(page);
set_status:
pm->status = err;
}
up_read(&mm->mmap_sem);
return 0;
}
/*
* Move a list of pages in the address space of the currently executing
* process.
*/
SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
const void __user * __user *, pages,
const int __user *, nodes,
int __user *, status, int, flags)
{
int err = 0;
int i;
struct task_struct *task;
nodemask_t task_nodes;
struct mm_struct *mm;
struct page_to_node *pm = NULL;
/* Check flags */
if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
return -EINVAL;
if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
return -EPERM;
/* Find the mm_struct */
read_lock(&tasklist_lock);
task = pid ? find_task_by_vpid(pid) : current;
if (!task) {
read_unlock(&tasklist_lock);
return -ESRCH;
}
mm = get_task_mm(task);
read_unlock(&tasklist_lock);
if (!mm)
return -EINVAL;
/*
* Check if this process has the right to modify the specified
* process. The right exists if the process has administrative
* capabilities, superuser privileges or the same
* userid as the target process.
*/
if ((current->euid != task->suid) && (current->euid != task->uid) &&
(current->uid != task->suid) && (current->uid != task->uid) &&
!capable(CAP_SYS_NICE)) {
err = -EPERM;
goto out2;
}
err = security_task_movememory(task);
if (err)
goto out2;
task_nodes = cpuset_mems_allowed(task);
/* Limit nr_pages so that the multiplication may not overflow */
if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
err = -E2BIG;
goto out2;
}
pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
if (!pm) {
err = -ENOMEM;
goto out2;
}
/*
* Get parameters from user space and initialize the pm
* array. Return various errors if the user did something wrong.
*/
for (i = 0; i < nr_pages; i++) {
const void __user *p;
err = -EFAULT;
if (get_user(p, pages + i))
goto out;
pm[i].addr = (unsigned long)p;
if (nodes) {
int node;
if (get_user(node, nodes + i))
goto out;
err = -ENODEV;
if (node < 0 || node >= MAX_NUMNODES)
goto out;
if (!node_state(node, N_HIGH_MEMORY))
goto out;
err = -EACCES;
if (!node_isset(node, task_nodes))
goto out;
pm[i].node = node;
} else
pm[i].node = 0; /* anything to not match MAX_NUMNODES */
}
/* End marker */
pm[nr_pages].node = MAX_NUMNODES;
if (nodes)
err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
else
err = do_pages_stat(mm, pm);
if (err >= 0)
/* Return status information */
for (i = 0; i < nr_pages; i++)
if (put_user(pm[i].status, status + i))
err = -EFAULT;
out:
vfree(pm);
out2:
mmput(mm);
return err;
}
/*
* Call migration functions in the vma_ops that may prepare
* memory in a vm for migration. migration functions may perform
* the migration for vmas that do not have an underlying page struct.
*/
int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
const nodemask_t *from, unsigned long flags)
{
struct vm_area_struct *vma;
int err = 0;
for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) {
if (vma->vm_ops && vma->vm_ops->migrate) {
err = vma->vm_ops->migrate(vma, to, from, flags);
if (err)
break;
}
}
return err;
}
#endif