int may_writepage;
+ /* Can pages be swapped as part of reclaim? */
+ int may_swap;
+
/* This context's SWAP_CLUSTER_MAX. If freeing memory for
* suspend, we effectively ignore SWAP_CLUSTER_MAX.
* In this context, it doesn't matter that we scan the
* Try to allocate it some swap space here.
*/
if (PageAnon(page) && !PageSwapCache(page)) {
+ if (!sc->may_swap)
+ goto keep_locked;
if (!add_to_swap(page, GFP_ATOMIC))
goto activate_locked;
}
* processes. Try to unmap it here.
*/
if (page_mapped(page) && mapping) {
- switch (try_to_unmap(page)) {
+ /*
+ * No unmapping if we do not swap
+ */
+ if (!sc->may_swap)
+ goto keep_locked;
+
+ switch (try_to_unmap(page, 0)) {
case SWAP_FAIL:
goto activate_locked;
case SWAP_AGAIN:
goto keep_locked;
if (!may_enter_fs)
goto keep_locked;
- if (laptop_mode && !sc->may_writepage)
+ if (!sc->may_writepage)
goto keep_locked;
/* Page is dirty, try to write it out here */
}
/*
- * Add isolated pages on the list back to the LRU
+ * Add isolated pages on the list back to the LRU.
*
* returns the number of pages put back.
*/
return count;
}
+/*
+ * Non migratable page
+ */
+int fail_migrate_page(struct page *newpage, struct page *page)
+{
+ return -EIO;
+}
+EXPORT_SYMBOL(fail_migrate_page);
+
/*
* swapout a single page
* page is locked upon entry, unlocked on exit
- *
- * return codes:
- * 0 = complete
- * 1 = retry
*/
static int swap_page(struct page *page)
{
struct address_space *mapping = page_mapping(page);
if (page_mapped(page) && mapping)
- if (try_to_unmap(page) != SWAP_SUCCESS)
+ if (try_to_unmap(page, 0) != SWAP_SUCCESS)
goto unlock_retry;
if (PageDirty(page)) {
unlock_page(page);
retry:
- return 1;
+ return -EAGAIN;
}
+EXPORT_SYMBOL(swap_page);
+
+/*
+ * 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 <clameter@sgi.com>
+ */
+
+/*
+ * Remove references for a page and establish the new page with the correct
+ * basic settings to be able to stop accesses to the page.
+ */
+int migrate_page_remove_references(struct page *newpage,
+ struct page *page, int nr_refs)
+{
+ struct address_space *mapping = page_mapping(page);
+ struct page **radix_pointer;
+
+ /*
+ * 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 1;
+
+ /*
+ * 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.
+ */
+ try_to_unmap(page, 1);
+
+ /*
+ * Give up if we were unable to remove all mappings.
+ */
+ if (page_mapcount(page))
+ return 1;
+
+ write_lock_irq(&mapping->tree_lock);
+
+ radix_pointer = (struct page **)radix_tree_lookup_slot(
+ &mapping->page_tree,
+ page_index(page));
+
+ if (!page_mapping(page) || page_count(page) != nr_refs ||
+ *radix_pointer != page) {
+ write_unlock_irq(&mapping->tree_lock);
+ return 1;
+ }
+
+ /*
+ * 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;
+ if (PageSwapCache(page)) {
+ SetPageSwapCache(newpage);
+ set_page_private(newpage, page_private(page));
+ }
+
+ *radix_pointer = newpage;
+ __put_page(page);
+ write_unlock_irq(&mapping->tree_lock);
+
+ 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)
+{
+ 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);
+ set_page_dirty(newpage);
+ }
+
+ ClearPageSwapCache(page);
+ 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);
+}
+EXPORT_SYMBOL(migrate_page_copy);
+
+/*
+ * 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 page *newpage, struct page *page)
+{
+ BUG_ON(PageWriteback(page)); /* Writeback must be complete */
+
+ if (migrate_page_remove_references(newpage, page, 2))
+ return -EAGAIN;
+
+ migrate_page_copy(newpage, page);
+
+ /*
+ * 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.
+ */
+ remove_from_swap(newpage);
+ return 0;
+}
+EXPORT_SYMBOL(migrate_page);
+
/*
* migrate_pages
*
* are movable anymore because t has become empty
* or no retryable pages exist anymore.
*
- * SIMPLIFIED VERSION: This implementation of migrate_pages
- * is only swapping out pages and never touches the second
- * list. The direct migration patchset
- * extends this function to avoid the use of swap.
+ * Return: Number of pages not migrated when "to" ran empty.
*/
-int migrate_pages(struct list_head *l, struct list_head *t)
+int migrate_pages(struct list_head *from, struct list_head *to,
+ struct list_head *moved, struct list_head *failed)
{
int retry;
- LIST_HEAD(failed);
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;
redo:
retry = 0;
- list_for_each_entry_safe(page, page2, l, lru) {
+ list_for_each_entry_safe(page, page2, from, lru) {
+ struct page *newpage = NULL;
+ struct address_space *mapping;
+
cond_resched();
+ rc = 0;
+ if (page_count(page) == 1)
+ /* page was freed from under us. So we are done. */
+ goto next;
+
+ if (to && list_empty(to))
+ break;
+
/*
* 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 retry_later;
+ goto next;
/*
* Only wait on writeback if we have already done a pass where
if (pass > 0) {
wait_on_page_writeback(page);
} else {
- if (PageWriteback(page)) {
- unlock_page(page);
- goto retry_later;
- }
+ if (PageWriteback(page))
+ goto unlock_page;
}
+ /*
+ * 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)) {
- unlock_page(page);
- list_move(&page->lru, &failed);
- nr_failed++;
- continue;
+ rc = -ENOMEM;
+ goto unlock_page;
}
}
+ if (!to) {
+ rc = swap_page(page);
+ goto next;
+ }
+
+ newpage = lru_to_page(to);
+ lock_page(newpage);
+
/*
- * Page is properly locked and writeback is complete.
+ * Pages are properly locked and writeback is complete.
* Try to migrate the page.
*/
- if (!swap_page(page))
- continue;
-retry_later:
- retry++;
+ mapping = page_mapping(page);
+ if (!mapping)
+ goto unlock_both;
+
+ if (mapping->a_ops->migratepage) {
+ rc = mapping->a_ops->migratepage(newpage, page);
+ goto unlock_both;
+ }
+
+ /*
+ * Trigger writeout if page is dirty
+ */
+ 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 */
+ }
+ }
+ /*
+ * If we have no buffer or can release the buffer
+ * then do a simple migration.
+ */
+ if (!page_has_buffers(page) ||
+ try_to_release_page(page, GFP_KERNEL)) {
+ rc = migrate_page(newpage, page);
+ goto unlock_both;
+ }
+
+ /*
+ * 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) {
+ unlock_page(newpage);
+ newpage = NULL;
+ rc = swap_page(page);
+ goto next;
+ }
+
+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);
+ }
}
if (retry && pass++ < 10)
goto redo;
if (!swapwrite)
current->flags &= ~PF_SWAPWRITE;
- if (!list_empty(&failed))
- list_splice(&failed, l);
-
return nr_failed + retry;
}
-static void lru_add_drain_per_cpu(void *dummy)
-{
- lru_add_drain();
-}
-
/*
* Isolate one page from the LRU lists and put it on the
- * indicated list. Do necessary cache draining if the
- * page is not on the LRU lists yet.
+ * indicated list with elevated refcount.
*
* Result:
* 0 = page not on LRU list
* 1 = page removed from LRU list and added to the specified list.
- * -ENOENT = page is being freed elsewhere.
*/
int isolate_lru_page(struct page *page)
{
- int rc = 0;
- struct zone *zone = page_zone(page);
+ int ret = 0;
-redo:
- spin_lock_irq(&zone->lru_lock);
- rc = __isolate_lru_page(page);
- if (rc == 1) {
- if (PageActive(page))
- del_page_from_active_list(zone, page);
- else
- del_page_from_inactive_list(zone, page);
- }
- spin_unlock_irq(&zone->lru_lock);
- if (rc == 0) {
- /*
- * Maybe this page is still waiting for a cpu to drain it
- * from one of the lru lists?
- */
- rc = schedule_on_each_cpu(lru_add_drain_per_cpu, NULL);
- if (rc == 0 && PageLRU(page))
- goto redo;
+ if (PageLRU(page)) {
+ struct zone *zone = page_zone(page);
+ spin_lock_irq(&zone->lru_lock);
+ if (TestClearPageLRU(page)) {
+ ret = 1;
+ get_page(page);
+ if (PageActive(page))
+ del_page_from_active_list(zone, page);
+ else
+ del_page_from_inactive_list(zone, page);
+ }
+ spin_unlock_irq(&zone->lru_lock);
}
- return rc;
+
+ return ret;
}
#endif
page = lru_to_page(src);
prefetchw_prev_lru_page(page, src, flags);
- switch (__isolate_lru_page(page)) {
- case 1:
- /* Succeeded to isolate page */
- list_move(&page->lru, dst);
- nr_taken++;
- break;
- case -ENOENT:
- /* Not possible to isolate */
- list_move(&page->lru, src);
- break;
- default:
+ if (!TestClearPageLRU(page))
BUG();
+ list_del(&page->lru);
+ if (get_page_testone(page)) {
+ /*
+ * It is being freed elsewhere
+ */
+ __put_page(page);
+ SetPageLRU(page);
+ list_add(&page->lru, src);
+ continue;
+ } else {
+ list_add(&page->lru, dst);
+ nr_taken++;
}
}
int i;
sc.gfp_mask = gfp_mask;
- sc.may_writepage = 0;
+ sc.may_writepage = !laptop_mode;
+ sc.may_swap = 1;
inc_page_state(allocstall);
total_scanned = 0;
total_reclaimed = 0;
sc.gfp_mask = GFP_KERNEL;
- sc.may_writepage = 0;
+ sc.may_writepage = !laptop_mode;
+ sc.may_swap = 1;
sc.nr_mapped = read_page_state(nr_mapped);
inc_page_state(pageoutrun);
}
module_init(kswapd_init)
+
+#ifdef CONFIG_NUMA
+/*
+ * Zone reclaim mode
+ *
+ * If non-zero call zone_reclaim when the number of free pages falls below
+ * the watermarks.
+ *
+ * In the future we may add flags to the mode. However, the page allocator
+ * should only have to check that zone_reclaim_mode != 0 before calling
+ * zone_reclaim().
+ */
+int zone_reclaim_mode __read_mostly;
+
+#define RECLAIM_OFF 0
+#define RECLAIM_ZONE (1<<0) /* Run shrink_cache on the zone */
+#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
+#define RECLAIM_SWAP (1<<2) /* Swap pages out during reclaim */
+#define RECLAIM_SLAB (1<<3) /* Do a global slab shrink if the zone is out of memory */
+
+/*
+ * Mininum time between zone reclaim scans
+ */
+int zone_reclaim_interval __read_mostly = 30*HZ;
+
+/*
+ * Priority for ZONE_RECLAIM. This determines the fraction of pages
+ * of a node considered for each zone_reclaim. 4 scans 1/16th of
+ * a zone.
+ */
+#define ZONE_RECLAIM_PRIORITY 4
+
+/*
+ * Try to free up some pages from this zone through reclaim.
+ */
+int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
+{
+ int nr_pages;
+ struct task_struct *p = current;
+ struct reclaim_state reclaim_state;
+ struct scan_control sc;
+ cpumask_t mask;
+ int node_id;
+
+ if (time_before(jiffies,
+ zone->last_unsuccessful_zone_reclaim + zone_reclaim_interval))
+ return 0;
+
+ if (!(gfp_mask & __GFP_WAIT) ||
+ zone->all_unreclaimable ||
+ atomic_read(&zone->reclaim_in_progress) > 0)
+ return 0;
+
+ node_id = zone->zone_pgdat->node_id;
+ mask = node_to_cpumask(node_id);
+ if (!cpus_empty(mask) && node_id != numa_node_id())
+ return 0;
+
+ sc.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE);
+ sc.may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP);
+ sc.nr_scanned = 0;
+ sc.nr_reclaimed = 0;
+ sc.priority = ZONE_RECLAIM_PRIORITY + 1;
+ sc.nr_mapped = read_page_state(nr_mapped);
+ sc.gfp_mask = gfp_mask;
+
+ disable_swap_token();
+
+ nr_pages = 1 << order;
+ if (nr_pages > SWAP_CLUSTER_MAX)
+ sc.swap_cluster_max = nr_pages;
+ else
+ sc.swap_cluster_max = SWAP_CLUSTER_MAX;
+
+ cond_resched();
+ p->flags |= PF_MEMALLOC;
+ reclaim_state.reclaimed_slab = 0;
+ p->reclaim_state = &reclaim_state;
+
+ /*
+ * Free memory by calling shrink zone with increasing priorities
+ * until we have enough memory freed.
+ */
+ do {
+ sc.priority--;
+ shrink_zone(zone, &sc);
+
+ } while (sc.nr_reclaimed < nr_pages && sc.priority > 0);
+
+ if (sc.nr_reclaimed < nr_pages && (zone_reclaim_mode & RECLAIM_SLAB)) {
+ /*
+ * shrink_slab does not currently allow us to determine
+ * how many pages were freed in the zone. So we just
+ * shake the slab and then go offnode for a single allocation.
+ *
+ * shrink_slab will free memory on all zones and may take
+ * a long time.
+ */
+ shrink_slab(sc.nr_scanned, gfp_mask, order);
+ sc.nr_reclaimed = 1; /* Avoid getting the off node timeout */
+ }
+
+ p->reclaim_state = NULL;
+ current->flags &= ~PF_MEMALLOC;
+
+ if (sc.nr_reclaimed == 0)
+ zone->last_unsuccessful_zone_reclaim = jiffies;
+
+ return sc.nr_reclaimed >= nr_pages;
+}
+#endif
+