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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
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@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;
_



[Index of Archives]     [Kernel Archive]     [IETF Annouce]     [DCCP]     [Netdev]     [Networking]     [Security]     [Bugtraq]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux SCSI]

  Powered by Linux