diff mbox series

[3/7] mm: migrate: simplify the file-backed pages validation when migrating its mapping

Message ID 20211111043237.NQd7m0u64%akpm@linux-foundation.org (mailing list archive)
State New
Headers show
Series [1/7] mm/page_owner.c: modify the type of argument "order" in some functions | expand

Commit Message

Andrew Morton Nov. 11, 2021, 4:32 a.m. UTC 
From: Baolin Wang <baolin.wang@linux.alibaba.com>
Subject: mm: migrate: simplify the file-backed pages validation when migrating its mapping

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@linux.alibaba.com
Link: https://lkml.kernel.org/r/df4c129fd8e86a95dbc55f4663d77441cc0d3bd1.1629447552.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate.c |    6 ------
 1 file changed, 6 deletions(-)
diff mbox series

Patch

--- 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;