linux-kernel - [PATCH v1 03/11] mm/memory_hotplug: simplify checking if all pages are isolated in offline

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Message-Id: <20200819101157.12723-4-david@redhat.com>
Date:   Wed, 19 Aug 2020 12:11:49 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>,
        Baoquan He <bhe@...hat.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Oscar Salvador <osalvador@...e.de>
Subject: [PATCH v1 03/11] mm/memory_hotplug: simplify checking if all pages are isolated in offline_pages()

We make sure that we cannot have any memory holes right at the beginning
of offline_pages(). We no longer need walk_system_ram_range() and can
call test_pages_isolated() directly.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Wei Yang <richard.weiyang@...ux.alibaba.com>
Cc: Baoquan He <bhe@...hat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@...il.com>
Cc: Oscar Salvador <osalvador@...e.de>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/memory_hotplug.c | 16 +---------------
 1 file changed, 1 insertion(+), 15 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 6856702af68d9..f64478349148d 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1384,17 +1384,6 @@ offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
 	return 0;
 }
 
-/*
- * Check all pages in range, recorded as memory resource, are isolated.
- */
-static int
-check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
-			void *data)
-{
-	return test_pages_isolated(start_pfn, start_pfn + nr_pages,
-				   MEMORY_OFFLINE);
-}
-
 static int __init cmdline_parse_movable_node(char *p)
 {
 	movable_node_enabled = true;
@@ -1579,10 +1568,7 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 			reason = "failure to dissolve huge pages";
 			goto failed_removal_isolated;
 		}
-		/* check again */
-		ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn,
-					    NULL, check_pages_isolated_cb);
-	} while (ret);
+	} while (test_pages_isolated(start_pfn, end_pfn, MEMORY_OFFLINE));
 
 	/* Ok, all of our target is isolated.
 	   We cannot do rollback at this point. */
-- 
2.26.2