From 0ef024621417fa3fcdeb2c3320f90ee34e18a5d9 Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Wed, 10 Nov 2021 20:32:37 -0800 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 Suggested-by: Matthew Wilcox Cc: Yang Shi Cc: Alistair Popple Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/migrate.c | 6 ------ 1 file changed, 6 deletions(-) (limited to 'mm/migrate.c') diff --git a/mm/migrate.c b/mm/migrate.c index a11e948593df..43dd88c7fcdc 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -404,12 +404,6 @@ int folio_migrate_mapping(struct address_space *mapping, 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; -- cgit