The patch titled
Swapless page migration: modify core logic
has been removed from the -mm tree. Its filename is
swapless-page-migration-modify-core-logic.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: Swapless page migration: modify core logic
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 | 53 +++++++++++++++++++------------------------------
2 files changed, 23 insertions(+), 34 deletions(-)
diff -puN mm/Kconfig~swapless-page-migration-modify-core-logic mm/Kconfig
--- a/mm/Kconfig~swapless-page-migration-modify-core-logic
+++ a/mm/Kconfig
@@ -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
--- a/mm/migrate.c~swapless-page-migration-modify-core-logic
+++ a/mm/migrate.c
@@ -254,14 +254,20 @@ static int migrate_page_move_mapping(str
{
struct page **radix_pointer;
+ if (!mapping) {
+ /* Anonymous page */
+ if (page_count(page) != 1)
+ return -EAGAIN;
+ return 0;
+ }
+
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) != 2 + !!PagePrivate(page) ||
+ if (page_count(page) != 2 + !!PagePrivate(page) ||
*radix_pointer != page) {
write_unlock_irq(&mapping->tree_lock);
return -EAGAIN;
@@ -271,10 +277,12 @@ 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);
@@ -308,7 +316,9 @@ 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);
@@ -353,16 +363,6 @@ 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);
@@ -530,23 +530,7 @@ 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)
@@ -569,9 +553,9 @@ 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
@@ -584,10 +568,15 @@ 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
mm-remove-vm_locked-before-remap_pfn_range-and-drop-vm_shm.patch
page-migration-support-a-vma-migration-function.patch
allow-migration-of-mlocked-pages.patch
zoned-vm-counters-create-vmstatc-h-from-page_allocc-h.patch
zoned-vm-counters-basic-zvc-zoned-vm-counter-implementation.patch
zoned-vm-counters-basic-zvc-zoned-vm-counter-implementation-tidy.patch
zoned-vm-counters-convert-nr_mapped-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_pagecache-to-per-zone-counter.patch
zoned-vm-counters-remove-nr_file_mapped-from-scan-control-structure.patch
zoned-vm-counters-remove-nr_file_mapped-from-scan-control-structure-fix.patch
zoned-vm-counters-split-nr_anon_pages-off-from-nr_file_mapped.patch
zoned-vm-counters-zone_reclaim-remove-proc-sys-vm-zone_reclaim_interval.patch
zoned-vm-counters-conversion-of-nr_slab-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_pagetables-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_dirty-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_writeback-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_unstable-to-per-zone-counter.patch
zoned-vm-counters-conversion-of-nr_bounce-to-per-zone-counter.patch
zoned-vm-counters-remove-useless-struct-wbs.patch
cpuset-remove-extra-cpuset_zone_allowed-check-in-__alloc_pages.patch
corrections-to-memory-barrier-doc.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
