The patch titled
Subject: mm: page migration remove_migration_ptes at lock+unlock level
has been added to the -mm tree. Its filename is
mm-page-migration-remove_migration_ptes-at-lockunlock-level.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page-migration-remove_migration_ptes-at-lockunlock-level.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page-migration-remove_migration_ptes-at-lockunlock-level.patch
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------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: mm: page migration remove_migration_ptes at lock+unlock level
Clean up page migration a little more by calling remove_migration_ptes()
from the same level, on success or on failure, from __unmap_and_move() or
from unmap_and_move_huge_page().
Don't reset page->mapping of a PageAnon old page in move_to_new_page(),
leave that to when the page is freed. Except for here in page migration,
it has been an invariant that a PageAnon (bit set in page->mapping) page
stays PageAnon until it is freed, and I think we're safer to keep to that.
And with the above rearrangement, it's necessary because zap_pte_range()
wants to identify whether a migration entry represents a file or an anon
page, to update the appropriate rss stats without waiting on it.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)
diff -puN mm/migrate.c~mm-page-migration-remove_migration_ptes-at-lockunlock-level mm/migrate.c
--- a/mm/migrate.c~mm-page-migration-remove_migration_ptes-at-lockunlock-level
+++ a/mm/migrate.c
@@ -722,7 +722,7 @@ static int fallback_migrate_page(struct
* MIGRATEPAGE_SUCCESS - success
*/
static int move_to_new_page(struct page *newpage, struct page *page,
- int page_was_mapped, enum migrate_mode mode)
+ enum migrate_mode mode)
{
struct address_space *mapping;
int rc;
@@ -755,19 +755,21 @@ static int move_to_new_page(struct page
* space which also has its own migratepage callback. This
* is the most common path for page migration.
*/
- rc = mapping->a_ops->migratepage(mapping,
- newpage, page, mode);
+ rc = mapping->a_ops->migratepage(mapping, newpage, page, mode);
else
rc = fallback_migrate_page(mapping, newpage, page, mode);
- if (rc != MIGRATEPAGE_SUCCESS) {
+ /*
+ * When successful, old pagecache page->mapping must be cleared before
+ * page is freed; but stats require that PageAnon be left as PageAnon.
+ */
+ if (rc == MIGRATEPAGE_SUCCESS) {
+ set_page_memcg(page, NULL);
+ if (!PageAnon(page))
+ page->mapping = NULL;
+ } else {
set_page_memcg(newpage, NULL);
newpage->mapping = NULL;
- } else {
- set_page_memcg(page, NULL);
- if (page_was_mapped)
- remove_migration_ptes(page, newpage);
- page->mapping = NULL;
}
return rc;
}
@@ -902,10 +904,11 @@ static int __unmap_and_move(struct page
}
if (!page_mapped(page))
- rc = move_to_new_page(newpage, page, page_was_mapped, mode);
+ rc = move_to_new_page(newpage, page, mode);
- if (rc && page_was_mapped)
- remove_migration_ptes(page, page);
+ if (page_was_mapped)
+ remove_migration_ptes(page,
+ rc == MIGRATEPAGE_SUCCESS ? newpage : page);
out_unlock_both:
unlock_page(newpage);
@@ -1066,10 +1069,11 @@ static int unmap_and_move_huge_page(new_
}
if (!page_mapped(hpage))
- rc = move_to_new_page(new_hpage, hpage, page_was_mapped, mode);
+ rc = move_to_new_page(new_hpage, hpage, mode);
- if (rc != MIGRATEPAGE_SUCCESS && page_was_mapped)
- remove_migration_ptes(hpage, hpage);
+ if (page_was_mapped)
+ remove_migration_ptes(hpage,
+ rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage);
unlock_page(new_hpage);
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx are
memcg-simplify-and-inline-__mem_cgroup_from_kmem-fix-2.patch
mm-documentation-undoc-non-linear-vmas.patch
mm-rmap-use-pte-lock-not-mmap_sem-to-set-pagemlocked.patch
mm-page-migration-fix-pagemlocked-on-migrated-pages.patch
mm-rename-mem_cgroup_migrate-to-mem_cgroup_replace_page.patch
mm-correct-a-couple-of-page-migration-comments.patch
mm-page-migration-use-the-put_new_page-whenever-necessary.patch
mm-page-migration-trylock-newpage-at-same-level-as-oldpage.patch
mm-page-migration-remove_migration_ptes-at-lockunlock-level.patch
mm-simplify-page-migrations-anon_vma-comment-and-flow.patch
mm-page-migration-use-migration-entry-for-swapcache-too.patch
mm-page-migration-avoid-touching-newpage-until-no-going-back.patch
mm-migrate-dirty-page-without-clear_page_dirty_for_io-etc.patch
mm-use-unsigned-int-for-page-order-fix-2.patch
mm-dont-split-thp-page-when-syscall-is-called-fix-4.patch
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