The patch titled
Subject: mm: migrate: simplify the file-backed pages validation when migrating its mapping
has been added to the -mm tree. Its filename is
mm-migrate-simplify-the-file-backed-pages-validation-when-migrating-its-mapping.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-migrate-simplify-the-file-backed-pages-validation-when-migrating-its-mapping.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-migrate-simplify-the-file-backed-pages-validation-when-migrating-its-mapping.patch
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------------------------------------------------------
From: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Subject: mm: migrate: simplify the file-backed pages validation when migrating its mapping
Patch series "Some cleanup for page migration", v3.
This patchset does some cleanups and improvements for page migration.
This patch (of 4):
There is no need to validate the file-backed page's refcount before trying
to freeze the page's expected refcount, instead we can rely on the
folio_ref_freeze() to validate if the page has the expected refcount
before migrating its mapping.
Moreover we are always under the page lock when migrating the page
mapping, which means nowhere else can remove it from the page cache, so we
can remove the xas_load() validation under the i_pages lock.
Link: https://lkml.kernel.org/r/cover.1629447552.git.baolin.wang@xxxxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/df4c129fd8e86a95dbc55f4663d77441cc0d3bd1.1629447552.git.baolin.wang@xxxxxxxxxxxxxxxxx
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 6 ------
1 file changed, 6 deletions(-)
--- a/mm/migrate.c~mm-migrate-simplify-the-file-backed-pages-validation-when-migrating-its-mapping
+++ a/mm/migrate.c
@@ -404,12 +404,6 @@ int folio_migrate_mapping(struct address
newzone = folio_zone(newfolio);
xas_lock_irq(&xas);
- if (folio_ref_count(folio) != expected_count ||
- xas_load(&xas) != folio) {
- xas_unlock_irq(&xas);
- return -EAGAIN;
- }
-
if (!folio_ref_freeze(folio, expected_count)) {
xas_unlock_irq(&xas);
return -EAGAIN;
_
Patches currently in -mm which might be from baolin.wang@xxxxxxxxxxxxxxxxx are
mm-memcontrol-set-the-correct-memcg-swappiness-restriction.patch
mm-mempolicy-use-readable-numa_no_node-macro-instead-of-magic-numer.patch
mm-migrate-simplify-the-file-backed-pages-validation-when-migrating-its-mapping.patch
mm-migrate-introduce-a-local-variable-to-get-the-number-of-pages.patch
mm-migrate-fix-the-incorrect-function-name-in-comments.patch
mm-migrate-change-to-use-bool-type-for-page_was_mapped.patch
