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-rw-r--r--mm/migrate.c1058
1 files changed, 687 insertions, 371 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 1c25040693d2..1c2a71aa05cd 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -15,6 +15,7 @@
#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>
@@ -23,13 +24,13 @@
#include <linux/topology.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
-#include <linux/swapops.h>
+#include <linux/writeback.h>
+#include <linux/mempolicy.h>
+#include <linux/vmalloc.h>
+#include <linux/security.h>
#include "internal.h"
-/* The maximum number of pages to take off the LRU for migration */
-#define MIGRATE_CHUNK_SIZE 256
-
#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
/*
@@ -64,16 +65,11 @@ int isolate_lru_page(struct page *page, struct list_head *pagelist)
}
/*
- * migrate_prep() needs to be called after we have compiled the list of pages
- * to be migrated using isolate_lru_page() but before we begin a series of calls
- * to migrate_pages().
+ * 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)
{
- /* Must have swap device for migration */
- if (nr_swap_pages <= 0)
- return -ENODEV;
-
/*
* Clear the LRU lists so pages can be isolated.
* Note that pages may be moved off the LRU after we have
@@ -87,7 +83,6 @@ int migrate_prep(void)
static inline void move_to_lru(struct page *page)
{
- list_del(&page->lru);
if (PageActive(page)) {
/*
* lru_cache_add_active checks that
@@ -113,113 +108,200 @@ int putback_lru_pages(struct list_head *l)
int count = 0;
list_for_each_entry_safe(page, page2, l, lru) {
+ list_del(&page->lru);
move_to_lru(page);
count++;
}
return count;
}
-/*
- * Non migratable page
- */
-int fail_migrate_page(struct page *newpage, struct page *page)
+static inline int is_swap_pte(pte_t pte)
{
- return -EIO;
+ return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
}
-EXPORT_SYMBOL(fail_migrate_page);
/*
- * swapout a single page
- * page is locked upon entry, unlocked on exit
+ * Restore a potential migration pte to a working pte entry
*/
-static int swap_page(struct page *page)
+static void remove_migration_pte(struct vm_area_struct *vma,
+ struct page *old, struct page *new)
{
- struct address_space *mapping = page_mapping(page);
+ 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;
+ }
- if (page_mapped(page) && mapping)
- if (try_to_unmap(page, 1) != SWAP_SUCCESS)
- goto unlock_retry;
+ ptl = pte_lockptr(mm, pmd);
+ spin_lock(ptl);
+ pte = *ptep;
+ if (!is_swap_pte(pte))
+ goto out;
- if (PageDirty(page)) {
- /* Page is dirty, try to write it out here */
- switch(pageout(page, mapping)) {
- case PAGE_KEEP:
- case PAGE_ACTIVATE:
- goto unlock_retry;
+ entry = pte_to_swp_entry(pte);
- case PAGE_SUCCESS:
- goto retry;
+ if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
+ goto out;
- case PAGE_CLEAN:
- ; /* try to free the page below */
- }
- }
+ get_page(new);
+ pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
+ if (is_write_migration_entry(entry))
+ pte = pte_mkwrite(pte);
+ set_pte_at(mm, addr, ptep, pte);
- if (PagePrivate(page)) {
- if (!try_to_release_page(page, GFP_KERNEL) ||
- (!mapping && page_count(page) == 1))
- goto unlock_retry;
- }
+ if (PageAnon(new))
+ page_add_anon_rmap(new, vma, addr);
+ else
+ page_add_file_rmap(new);
- if (remove_mapping(mapping, page)) {
- /* Success */
- unlock_page(page);
- return 0;
- }
+ /* No need to invalidate - it was non-present before */
+ update_mmu_cache(vma, addr, pte);
+ lazy_mmu_prot_update(pte);
-unlock_retry:
- unlock_page(page);
+out:
+ pte_unmap_unlock(ptep, ptl);
+}
-retry:
- return -EAGAIN;
+/*
+ * 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);
}
/*
- * Remove references for a page and establish the new page with the correct
- * basic settings to be able to stop accesses to the page.
+ * Must hold mmap_sem lock on at least one of the vmas containing
+ * the page so that the anon_vma cannot vanish.
*/
-int migrate_page_remove_references(struct page *newpage,
- struct page *page, int nr_refs)
+static void remove_anon_migration_ptes(struct page *old, struct page *new)
{
- struct address_space *mapping = page_mapping(page);
- struct page **radix_pointer;
+ struct anon_vma *anon_vma;
+ struct vm_area_struct *vma;
+ unsigned long mapping;
- /*
- * Avoid doing any of the following work if the page count
- * indicates that the page is in use or truncate has removed
- * the page.
- */
- if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
- return -EAGAIN;
+ mapping = (unsigned long)new->mapping;
- /*
- * Establish swap ptes for anonymous pages or destroy pte
- * maps for files.
- *
- * In order to reestablish file backed mappings the fault handlers
- * will take the radix tree_lock which may then be used to stop
- * processses from accessing this page until the new page is ready.
- *
- * A process accessing via a swap pte (an anonymous page) will take a
- * page_lock on the old page which will block the process until the
- * migration attempt is complete. At that time the PageSwapCache bit
- * will be examined. If the page was migrated then the PageSwapCache
- * bit will be clear and the operation to retrieve the page will be
- * retried which will find the new page in the radix tree. Then a new
- * direct mapping may be generated based on the radix tree contents.
- *
- * If the page was not migrated then the PageSwapCache bit
- * is still set and the operation may continue.
- */
- if (try_to_unmap(page, 1) == SWAP_FAIL)
- /* A vma has VM_LOCKED set -> permanent failure */
- return -EPERM;
+ if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
+ return;
/*
- * Give up if we were unable to remove all mappings.
+ * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
*/
- if (page_mapcount(page))
- return -EAGAIN;
+ 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);
+
+ get_page(page);
+ 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)
+{
+ struct page **radix_pointer;
+
+ if (!mapping) {
+ /* Anonymous page */
+ if (page_count(page) != 1)
+ return -EAGAIN;
+ return 0;
+ }
write_lock_irq(&mapping->tree_lock);
@@ -227,7 +309,7 @@ int migrate_page_remove_references(struct page *newpage,
&mapping->page_tree,
page_index(page));
- if (!page_mapping(page) || page_count(page) != nr_refs ||
+ if (page_count(page) != 2 + !!PagePrivate(page) ||
*radix_pointer != page) {
write_unlock_irq(&mapping->tree_lock);
return -EAGAIN;
@@ -235,19 +317,14 @@ int migrate_page_remove_references(struct page *newpage,
/*
* Now we know that no one else is looking at the page.
- *
- * Certain minimal information about a page must be available
- * in order for other subsystems to properly handle the page if they
- * find it through the radix tree update before we are finished
- * copying the page.
*/
get_page(newpage);
- newpage->index = page->index;
- newpage->mapping = page->mapping;
+#ifdef CONFIG_SWAP
if (PageSwapCache(page)) {
SetPageSwapCache(newpage);
set_page_private(newpage, page_private(page));
}
+#endif
*radix_pointer = newpage;
__put_page(page);
@@ -255,12 +332,11 @@ int migrate_page_remove_references(struct page *newpage,
return 0;
}
-EXPORT_SYMBOL(migrate_page_remove_references);
/*
* Copy the page to its new location
*/
-void migrate_page_copy(struct page *newpage, struct page *page)
+static void migrate_page_copy(struct page *newpage, struct page *page)
{
copy_highpage(newpage, page);
@@ -282,7 +358,9 @@ void migrate_page_copy(struct page *newpage, struct page *page)
set_page_dirty(newpage);
}
+#ifdef CONFIG_SWAP
ClearPageSwapCache(page);
+#endif
ClearPageActive(page);
ClearPagePrivate(page);
set_page_private(page, 0);
@@ -295,7 +373,18 @@ void migrate_page_copy(struct page *newpage, struct page *page)
if (PageWriteback(newpage))
end_page_writeback(newpage);
}
-EXPORT_SYMBOL(migrate_page_copy);
+
+/************************************************************
+ * 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
@@ -303,51 +392,286 @@ EXPORT_SYMBOL(migrate_page_copy);
*
* Pages are locked upon entry and exit.
*/
-int migrate_page(struct page *newpage, struct page *page)
+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_remove_references(newpage, page, 2);
+ rc = migrate_page_move_mapping(mapping, newpage, page);
+
+ if (rc)
+ return rc;
+
+ migrate_page_copy(newpage, page);
+ return 0;
+}
+EXPORT_SYMBOL(migrate_page);
+
+/*
+ * 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);
+
+/*
+ * 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;
+
/*
- * Remove auxiliary swap entries and replace
- * them with real ptes.
- *
- * Note that a real pte entry will allow processes that are not
- * waiting on the page lock to use the new page via the page tables
- * before the new page is unlocked.
+ * 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_from_swap(newpage);
- return 0;
+ 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 (page_has_buffers(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 (TestSetPageLocked(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);
+
+ if (!newpage)
+ return -ENOMEM;
+
+ if (page_count(page) == 1)
+ /* page was freed from under us. So we are done. */
+ goto move_newpage;
+
+ rc = -EAGAIN;
+ if (TestSetPageLocked(page)) {
+ if (!force)
+ goto move_newpage;
+ lock_page(page);
+ }
+
+ if (PageWriteback(page)) {
+ if (!force)
+ goto unlock;
+ wait_on_page_writeback(page);
+ }
+
+ /*
+ * Establish migration ptes or remove ptes
+ */
+ if (try_to_unmap(page, 1) != SWAP_FAIL) {
+ if (!page_mapped(page))
+ rc = move_to_new_page(newpage, page);
+ } else
+ /* A vma has VM_LOCKED set -> permanent failure */
+ rc = -EPERM;
+
+ if (rc)
+ remove_migration_ptes(page, page);
+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:
+ /*
+ * 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;
}
-EXPORT_SYMBOL(migrate_page);
/*
* migrate_pages
*
- * Two lists are passed to this function. The first list
- * contains the pages isolated from the LRU to be migrated.
- * The second list contains new pages that the pages isolated
- * can be moved to. If the second list is NULL then all
- * pages are swapped out.
+ * 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.
+ * or no retryable pages exist anymore. All pages will be
+ * retruned to the LRU or freed.
*
- * Return: Number of pages not migrated when "to" ran empty.
+ * Return: Number of pages not migrated or error code.
*/
-int migrate_pages(struct list_head *from, struct list_head *to,
- struct list_head *moved, struct list_head *failed)
+int migrate_pages(struct list_head *from,
+ new_page_t get_new_page, unsigned long private)
{
- int retry;
+ int retry = 1;
int nr_failed = 0;
int pass = 0;
struct page *page;
@@ -358,305 +682,297 @@ int migrate_pages(struct list_head *from, struct list_head *to,
if (!swapwrite)
current->flags |= PF_SWAPWRITE;
-redo:
- retry = 0;
+ 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;
- list_for_each_entry_safe(page, page2, from, lru) {
- struct page *newpage = NULL;
- struct address_space *mapping;
+ putback_lru_pages(from);
- cond_resched();
+ if (rc)
+ return rc;
- rc = 0;
- if (page_count(page) == 1)
- /* page was freed from under us. So we are done. */
- goto next;
+ return nr_failed + retry;
+}
- if (to && list_empty(to))
- break;
+#ifdef CONFIG_NUMA
+/*
+ * Move a list of individual pages
+ */
+struct page_to_node {
+ unsigned long addr;
+ struct page *page;
+ int node;
+ int status;
+};
- /*
- * Skip locked pages during the first two passes to give the
- * functions holding the lock time to release the page. Later we
- * use lock_page() to have a higher chance of acquiring the
- * lock.
- */
- rc = -EAGAIN;
- if (pass > 2)
- lock_page(page);
- else
- if (TestSetPageLocked(page))
- goto next;
+static struct page *new_page_node(struct page *p, unsigned long private,
+ int **result)
+{
+ struct page_to_node *pm = (struct page_to_node *)private;
- /*
- * Only wait on writeback if we have already done a pass where
- * we we may have triggered writeouts for lots of pages.
- */
- if (pass > 0) {
- wait_on_page_writeback(page);
- } else {
- if (PageWriteback(page))
- goto unlock_page;
- }
+ while (pm->node != MAX_NUMNODES && pm->page != p)
+ pm++;
- /*
- * Anonymous pages must have swap cache references otherwise
- * the information contained in the page maps cannot be
- * preserved.
- */
- if (PageAnon(page) && !PageSwapCache(page)) {
- if (!add_to_swap(page, GFP_KERNEL)) {
- rc = -ENOMEM;
- goto unlock_page;
- }
- }
+ if (pm->node == MAX_NUMNODES)
+ return NULL;
- if (!to) {
- rc = swap_page(page);
- goto next;
- }
+ *result = &pm->status;
- newpage = lru_to_page(to);
- lock_page(newpage);
+ return alloc_pages_node(pm->node, GFP_HIGHUSER, 0);
+}
- /*
- * Pages are properly locked and writeback is complete.
- * Try to migrate the page.
- */
- mapping = page_mapping(page);
- if (!mapping)
- goto unlock_both;
+/*
+ * 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);
- 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(newpage, page);
- goto unlock_both;
- }
-
- /* Make sure the dirty bit is up to date */
- if (try_to_unmap(page, 1) == SWAP_FAIL) {
- rc = -EPERM;
- goto unlock_both;
- }
+ down_read(&mm->mmap_sem);
- if (page_mapcount(page)) {
- rc = -EAGAIN;
- goto unlock_both;
- }
+ /*
+ * 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;
/*
- * Default handling if a filesystem does not provide
- * a migration function. We can only migrate clean
- * pages so try to write out any dirty pages first.
+ * A valid page pointer that will not match any of the
+ * pages that will be moved.
*/
- if (PageDirty(page)) {
- switch (pageout(page, mapping)) {
- case PAGE_KEEP:
- case PAGE_ACTIVATE:
- goto unlock_both;
-
- case PAGE_SUCCESS:
- unlock_page(newpage);
- goto next;
-
- case PAGE_CLEAN:
- ; /* try to migrate the page below */
- }
- }
+ pp->page = ZERO_PAGE(0);
- /*
- * Buffers are managed in a filesystem specific way.
- * We must have no buffers or drop them.
- */
- if (!page_has_buffers(page) ||
- try_to_release_page(page, GFP_KERNEL)) {
- rc = migrate_page(newpage, page);
- goto unlock_both;
- }
+ err = -EFAULT;
+ vma = find_vma(mm, pp->addr);
+ if (!vma)
+ goto set_status;
- /*
- * On early passes with mapped pages simply
- * retry. There may be a lock held for some
- * buffers that may go away. Later
- * swap them out.
- */
- if (pass > 4) {
+ page = follow_page(vma, pp->addr, FOLL_GET);
+ 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)
/*
- * Persistently unable to drop buffers..... As a
- * measure of last resort we fall back to
- * swap_page().
+ * Node already in the right place
*/
- unlock_page(newpage);
- newpage = NULL;
- rc = swap_page(page);
- goto next;
- }
+ goto put_and_set;
-unlock_both:
- unlock_page(newpage);
-
-unlock_page:
- unlock_page(page);
-
-next:
- if (rc == -EAGAIN) {
- retry++;
- } else if (rc) {
- /* Permanent failure */
- list_move(&page->lru, failed);
- nr_failed++;
- } else {
- if (newpage) {
- /* Successful migration. Return page to LRU */
- move_to_lru(newpage);
- }
- list_move(&page->lru, moved);
- }
+ 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 (retry && pass++ < 10)
- goto redo;
- if (!swapwrite)
- current->flags &= ~PF_SWAPWRITE;
+ if (!list_empty(&pagelist))
+ err = migrate_pages(&pagelist, new_page_node,
+ (unsigned long)pm);
+ else
+ err = -ENOENT;
- return nr_failed + retry;
+ up_read(&mm->mmap_sem);
+ return err;
}
/*
- * Migration function for pages with buffers. This function can only be used
- * if the underlying filesystem guarantees that no other references to "page"
- * exist.
+ * 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.
*/
-int buffer_migrate_page(struct page *newpage, struct page *page)
+static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
{
- struct address_space *mapping = page->mapping;
- struct buffer_head *bh, *head;
- int rc;
+ 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 = -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;
+ }
- if (!mapping)
- return -EAGAIN;
+ up_read(&mm->mmap_sem);
+ return 0;
+}
- if (!page_has_buffers(page))
- return migrate_page(newpage, page);
+/*
+ * Move a list of pages in the address space of the currently executing
+ * process.
+ */
+asmlinkage long sys_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;
- head = page_buffers(page);
+ /* Check flags */
+ if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
+ return -EINVAL;
- rc = migrate_page_remove_references(newpage, page, 3);
+ if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
+ return -EPERM;
- if (rc)
- return rc;
+ /* Find the mm_struct */
+ read_lock(&tasklist_lock);
+ task = pid ? find_task_by_pid(pid) : current;
+ if (!task) {
+ read_unlock(&tasklist_lock);
+ return -ESRCH;
+ }
+ mm = get_task_mm(task);
+ read_unlock(&tasklist_lock);
- bh = head;
- do {
- get_bh(bh);
- lock_buffer(bh);
- bh = bh->b_this_page;
+ if (!mm)
+ return -EINVAL;
- } while (bh != head);
+ /*
+ * 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;
+ }
- ClearPagePrivate(page);
- set_page_private(newpage, page_private(page));
- set_page_private(page, 0);
- put_page(page);
- get_page(newpage);
+ err = security_task_movememory(task);
+ if (err)
+ goto out2;
- bh = head;
- do {
- set_bh_page(bh, newpage, bh_offset(bh));
- bh = bh->b_this_page;
- } while (bh != head);
+ task_nodes = cpuset_mems_allowed(task);
- SetPagePrivate(newpage);
+ /* 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;
+ }
- migrate_page_copy(newpage, page);
+ pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
+ if (!pm) {
+ err = -ENOMEM;
+ goto out2;
+ }
- bh = head;
- do {
- unlock_buffer(bh);
- put_bh(bh);
- bh = bh->b_this_page;
+ /*
+ * 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 *p;
- } while (bh != head);
+ err = -EFAULT;
+ if (get_user(p, pages + i))
+ goto out;
- return 0;
-}
-EXPORT_SYMBOL(buffer_migrate_page);
+ pm[i].addr = (unsigned long)p;
+ if (nodes) {
+ int node;
-/*
- * Migrate the list 'pagelist' of pages to a certain destination.
- *
- * Specify destination with either non-NULL vma or dest_node >= 0
- * Return the number of pages not migrated or error code
- */
-int migrate_pages_to(struct list_head *pagelist,
- struct vm_area_struct *vma, int dest)
-{
- LIST_HEAD(newlist);
- LIST_HEAD(moved);
- LIST_HEAD(failed);
- int err = 0;
- unsigned long offset = 0;
- int nr_pages;
- struct page *page;
- struct list_head *p;
+ if (get_user(node, nodes + i))
+ goto out;
-redo:
- nr_pages = 0;
- list_for_each(p, pagelist) {
- if (vma) {
- /*
- * The address passed to alloc_page_vma is used to
- * generate the proper interleave behavior. We fake
- * the address here by an increasing offset in order
- * to get the proper distribution of pages.
- *
- * No decision has been made as to which page
- * a certain old page is moved to so we cannot
- * specify the correct address.
- */
- page = alloc_page_vma(GFP_HIGHUSER, vma,
- offset + vma->vm_start);
- offset += PAGE_SIZE;
- }
- else
- page = alloc_pages_node(dest, GFP_HIGHUSER, 0);
+ err = -ENODEV;
+ if (!node_online(node))
+ goto out;
- if (!page) {
- err = -ENOMEM;
- goto out;
+ err = -EACCES;
+ if (!node_isset(node, task_nodes))
+ goto out;
+
+ pm[i].node = node;
}
- list_add_tail(&page->lru, &newlist);
- nr_pages++;
- if (nr_pages > MIGRATE_CHUNK_SIZE)
- break;
}
- err = migrate_pages(pagelist, &newlist, &moved, &failed);
+ /* 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);
- putback_lru_pages(&moved); /* Call release pages instead ?? */
+ if (err >= 0)
+ /* Return status information */
+ for (i = 0; i < nr_pages; i++)
+ if (put_user(pm[i].status, status + i))
+ err = -EFAULT;
- if (err >= 0 && list_empty(&newlist) && !list_empty(pagelist))
- goto redo;
out:
- /* Return leftover allocated pages */
- while (!list_empty(&newlist)) {
- page = list_entry(newlist.next, struct page, lru);
- list_del(&page->lru);
- __free_page(page);
- }
- list_splice(&failed, pagelist);
- if (err < 0)
- return err;
-
- /* Calculate number of leftover pages */
- nr_pages = 0;
- list_for_each(p, pagelist)
- nr_pages++;
- return nr_pages;
+ vfree(pm);
+out2:
+ mmput(mm);
+ return err;
}
+#endif
+