The patch titled
Swapless page migration: modify core logic
has been added to the -mm tree. Its filename is
swapless-page-migration-modify-core-logic.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
From: Christoph Lameter <clameter@xxxxxxx>
Use the migration entries for page migration
This modifies the migration code to use the new migration entries. It now
becomes possible to migrate anonymous pages without having to add a swap
entry.
We add a couple of new functions to replace migration entries with the proper
ptes.
We cannot take the tree_lock for migrating anonymous pages anymore. However,
we know that we hold the only remaining reference to the page when the page
count reaches 1.
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/Kconfig | 4 +--
mm/migrate.c | 50 +++++++++++++++++++------------------------------
2 files changed, 22 insertions(+), 32 deletions(-)
diff -puN mm/Kconfig~swapless-page-migration-modify-core-logic mm/Kconfig
--- devel/mm/Kconfig~swapless-page-migration-modify-core-logic 2006-04-29 00:20:56.000000000 -0700
+++ devel-akpm/mm/Kconfig 2006-04-29 00:20:56.000000000 -0700
@@ -138,8 +138,8 @@ config SPLIT_PTLOCK_CPUS
#
config MIGRATION
bool "Page migration"
- def_bool y if NUMA
- depends on SWAP && NUMA
+ def_bool y
+ depends on NUMA
help
Allows the migration of the physical location of pages of processes
while the virtual addresses are not changed. This is useful for
diff -puN mm/migrate.c~swapless-page-migration-modify-core-logic mm/migrate.c
--- devel/mm/migrate.c~swapless-page-migration-modify-core-logic 2006-04-29 00:20:56.000000000 -0700
+++ devel-akpm/mm/migrate.c 2006-04-29 00:20:56.000000000 -0700
@@ -258,6 +258,13 @@ static int migrate_page_move_mapping(str
{
struct page **radix_pointer;
+ if (!mapping) {
+ /* Anonymous page */
+ if (page_count(page) != 1 || !page->mapping)
+ return -EAGAIN;
+ return 0;
+ }
+
write_lock_irq(&mapping->tree_lock);
radix_pointer = (struct page **)radix_tree_lookup_slot(
@@ -275,10 +282,12 @@ static int migrate_page_move_mapping(str
* Now we know that no one else is looking at the page.
*/
get_page(newpage);
+#ifdef CONFIG_SWAP
if (PageSwapCache(page)) {
SetPageSwapCache(newpage);
set_page_private(newpage, page_private(page));
}
+#endif
*radix_pointer = newpage;
__put_page(page);
@@ -312,7 +321,9 @@ static void migrate_page_copy(struct pag
set_page_dirty(newpage);
}
+#ifdef CONFIG_SWAP
ClearPageSwapCache(page);
+#endif
ClearPageActive(page);
ClearPagePrivate(page);
set_page_private(page, 0);
@@ -357,16 +368,6 @@ int migrate_page(struct address_space *m
return rc;
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);
@@ -534,23 +535,7 @@ redo:
goto unlock_page;
/*
- * 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.
+ * Establish migration ptes or remove ptes
*/
rc = -EPERM;
if (try_to_unmap(page, 1) == SWAP_FAIL)
@@ -573,9 +558,9 @@ redo:
*/
mapping = page_mapping(page);
if (!mapping)
- goto unlock_both;
+ rc = migrate_page(mapping, newpage, page);
- if (mapping->a_ops->migratepage)
+ else if (mapping->a_ops->migratepage)
/*
* Most pages have a mapping and most filesystems
* should provide a migration function. Anonymous
@@ -588,10 +573,15 @@ redo:
else
rc = fallback_migrate_page(mapping, newpage, page);
-unlock_both:
+ if (!rc)
+ remove_migration_ptes(page, newpage);
+
unlock_page(newpage);
unlock_page:
+ if (rc)
+ remove_migration_ptes(page, page);
+
unlock_page(page);
next:
_
Patches currently in -mm which might be from clameter@xxxxxxx are
origin.patch
page-migration-fix-fallback-behavior-for-dirty-pages.patch
page-migration-make-do_swap_page-redo-the-fault.patch
slab-extract-cache_free_alien-from-__cache_free.patch
migration-remove-unnecessary-pageswapcache-checks.patch
page-migration-cleanup-rename-ignrefs-to-migration.patch
page-migration-cleanup-group-functions.patch
page-migration-cleanup-remove-useless-definitions.patch
page-migration-cleanup-drop-nr_refs-in-remove_references.patch
page-migration-cleanup-extract-try_to_unmap-from-migration-functions.patch
page-migration-cleanup-pass-mapping-to-migration-functions.patch
page-migration-cleanup-move-fallback-handling-into-special-function.patch
swapless-pm-add-r-w-migration-entries.patch
swapless-page-migration-rip-out-swap-based-logic.patch
swapless-page-migration-modify-core-logic.patch
more-page-migration-do-not-inc-dec-rss-counters.patch
more-page-migration-use-migration-entries-for-file-pages.patch
-
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