diff options
Diffstat (limited to 'mm/migrate.c')
| -rw-r--r-- | mm/migrate.c | 1151 |
1 files changed, 1151 insertions, 0 deletions
diff --git a/mm/migrate.c b/mm/migrate.c new file mode 100644 index 0000000..7fc57cc --- /dev/null +++ b/mm/migrate.c @@ -0,0 +1,1151 @@ +/* + * 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)) + +/* + * 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; +} + +/* + * Add isolated pages on the list back to the LRU under page lock + * to avoid leaking evictable pages back onto unevictable list. + * + * 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); + putback_lru_page(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); + + return 0; +} + +/* + * Copy the page to its new location + */ +static void migrate_page_copy(struct page *newpage, struct page *page) +{ + int anon; + + copy_highpage(newpage, page); + + if (PageError(page)) + SetPageError(newpage); + if (PageReferenced(page)) + SetPageReferenced(newpage); + if (PageUptodate(page)) + SetPageUptodate(newpage); + if (TestClearPageActive(page)) { + VM_BUG_ON(PageUnevictable(page)); + SetPageActive(newpage); + } else + unevictable_migrate_page(newpage, page); + 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); + } + + mlock_migrate_page(newpage, page); + +#ifdef CONFIG_SWAP + ClearPageSwapCache(page); +#endif + ClearPagePrivate(page); + set_page_private(page, 0); + /* page->mapping contains a flag for PageAnon() */ + anon = PageAnon(page); + page->mapping = NULL; + + if (!anon) /* This page was removed from radix-tree. */ + mem_cgroup_uncharge_cache_page(page); + + /* + * 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 != AOP_WRITEPAGE_ACTIVATE) + /* unlocked. Relock */ + lock_page(page); + + return (rc < 0) ? -EIO : -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. + * + * Return value: + * < 0 - error code + * == 0 - success + */ +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; + if (PageSwapBacked(page)) + SetPageSwapBacked(newpage); + + 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); + putback_lru_page(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. + */ + putback_lru_page(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. + * The pm array ends with node = MAX_NUMNODES. + */ +static int do_move_page_to_node_array(struct mm_struct *mm, + struct page_to_node *pm, + int migrate_all) +{ + int err; + struct page_to_node *pp; + LIST_HEAD(pagelist); + + migrate_prep(); + down_read(&mm->mmap_sem); + + /* + * Build a list of pages to migrate + */ + 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); + if (!err) + list_add_tail(&page->lru, &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; + } + + err = 0; + if (!list_empty(&pagelist)) + err = migrate_pages(&pagelist, new_page_node, + (unsigned long)pm); + + up_read(&mm->mmap_sem); + return err; +} + +/* + * Migrate an array of page address onto an array of nodes and fill + * the corresponding array of status. + */ +static int do_pages_move(struct mm_struct *mm, struct task_struct *task, + unsigned long nr_pages, + const void __user * __user *pages, + const int __user *nodes, + int __user *status, int flags) +{ + struct page_to_node *pm = NULL; + nodemask_t task_nodes; + int err = 0; + int i; + + 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 out; + } + + pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node)); + if (!pm) { + err = -ENOMEM; + goto out; + } + + /* + * 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; + + pm[i].addr = (unsigned long)p; + if (nodes) { + int node; + + if (get_user(node, nodes + i)) + goto out_pm; + + err = -ENODEV; + if (!node_state(node, N_HIGH_MEMORY)) + goto out_pm; + + err = -EACCES; + if (!node_isset(node, task_nodes)) + goto out_pm; + + pm[i].node = node; + } else + pm[i].node = 0; /* anything to not match MAX_NUMNODES */ + } + /* End marker */ + pm[nr_pages].node = MAX_NUMNODES; + + err = do_move_page_to_node_array(mm, pm, flags & MPOL_MF_MOVE_ALL); + if (err >= 0) + /* Return status information */ + for (i = 0; i < nr_pages; i++) + if (put_user(pm[i].status, status + i)) + err = -EFAULT; + +out_pm: + vfree(pm); +out: + return err; +} + +/* + * Determine the nodes of an array of pages and store it in an array of status. + */ +static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, + const void __user **pages, int *status) +{ + unsigned long i; + + down_read(&mm->mmap_sem); + + for (i = 0; i < nr_pages; i++) { + unsigned long addr = (unsigned long)(*pages); + struct vm_area_struct *vma; + struct page *page; + int err = -EFAULT; + + vma = find_vma(mm, addr); + if (!vma) + goto set_status; + + page = follow_page(vma, 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: + *status = err; + + pages++; + status++; + } + + up_read(&mm->mmap_sem); +} + +/* + * Determine the nodes of a user array of pages and store it in + * a user array of status. + */ +static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, + const void __user * __user *pages, + int __user *status) +{ +#define DO_PAGES_STAT_CHUNK_NR 16 + const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; + int chunk_status[DO_PAGES_STAT_CHUNK_NR]; + unsigned long i, chunk_nr = DO_PAGES_STAT_CHUNK_NR; + int err; + + for (i = 0; i < nr_pages; i += chunk_nr) { + if (chunk_nr + i > nr_pages) + chunk_nr = nr_pages - i; + + err = copy_from_user(chunk_pages, &pages[i], + chunk_nr * sizeof(*chunk_pages)); + if (err) { + err = -EFAULT; + goto out; + } + + do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); + + err = copy_to_user(&status[i], chunk_status, + chunk_nr * sizeof(*chunk_status)); + if (err) { + err = -EFAULT; + goto out; + } + } + err = 0; + +out: + return err; +} + +/* + * 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) +{ + struct task_struct *task; + struct mm_struct *mm; + int err; + + /* 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 out; + } + + err = security_task_movememory(task); + if (err) + goto out; + + if (nodes) { + err = do_pages_move(mm, task, nr_pages, pages, nodes, status, + flags); + } else { + err = do_pages_stat(mm, nr_pages, pages, status); + } + +out: + 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 |
