linux-kernel - [PATCH v1 06/11] mm/memory_hotplug: drop nr_isolate_pageblock in offline

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Date:   Wed, 19 Aug 2020 12:11:52 +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 06/11] mm/memory_hotplug: drop nr_isolate_pageblock in offline_pages()

We make sure that we cannot have any memory holes right at the beginning
of offline_pages() and we only support to online/offline full sections.
Both, sections and pageblocks are a power of two in size, and sections
always span full pageblocks.

We can directly calculate the number of isolated pageblocks from nr_pages.

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 | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 50aa5df696e9d..098361fcb4504 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1460,10 +1460,10 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 {
 	const unsigned long end_pfn = start_pfn + nr_pages;
 	unsigned long pfn, system_ram_pages = 0;
-	int ret, node, nr_isolate_pageblock;
 	unsigned long flags;
 	struct zone *zone;
 	struct memory_notify arg;
+	int ret, node;
 	char *reason;
 
 	/* We can only offline full sections (e.g., SECTION_IS_ONLINE) */
@@ -1507,7 +1507,6 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 		reason = "failure to isolate range";
 		goto failed_removal;
 	}
-	nr_isolate_pageblock = ret;
 
 	arg.start_pfn = start_pfn;
 	arg.nr_pages = nr_pages;
@@ -1569,7 +1568,7 @@ int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 	 * pageblocks zone counter here.
 	 */
 	spin_lock_irqsave(&zone->lock, flags);
-	zone->nr_isolate_pageblock -= nr_isolate_pageblock;
+	zone->nr_isolate_pageblock -= nr_pages / pageblock_nr_pages;
 	spin_unlock_irqrestore(&zone->lock, flags);
 
 	/* removal success */
-- 
2.26.2