linux-kernel - [PATCH 1/3] memory-hotplug: add move_pfn

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Date:	Mon,  9 May 2016 12:53:37 -0500
From:	Reza Arbab <arbab@...ux.vnet.ibm.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Daniel Kiper <daniel.kiper@...cle.com>,
	Dan Williams <dan.j.williams@...el.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Tang Chen <tangchen@...fujitsu.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	David Vrabel <david.vrabel@...rix.com>,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Andrew Banman <abanman@....com>, Chen Yucong <slaoub@...il.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Reza Arbab <arbab@...ux.vnet.ibm.com>
Subject: [PATCH 1/3] memory-hotplug: add move_pfn_range()

Add move_pfn_range(), a wrapper to call move_pfn_range_left() or
move_pfn_range_right().

No functional change. This will be utilized by a later patch.

Signed-off-by: Reza Arbab <arbab@...ux.vnet.ibm.com>
---
 mm/memory_hotplug.c | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index aa34431..6b4b005 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -434,6 +434,25 @@ out_fail:
 	return -1;
 }
 
+static struct zone * __meminit move_pfn_range(int zone_shift,
+		unsigned long start_pfn, unsigned long end_pfn)
+{
+	struct zone *zone = page_zone(pfn_to_page(start_pfn));
+	int ret = 0;
+
+	if (zone_shift < 0)
+		ret = move_pfn_range_left(zone + zone_shift, zone,
+					  start_pfn, end_pfn);
+	else if (zone_shift)
+		ret = move_pfn_range_right(zone, zone + zone_shift,
+					   start_pfn, end_pfn);
+
+	if (ret)
+		return NULL;
+
+	return zone + zone_shift;
+}
+
 static void __meminit grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
 				      unsigned long end_pfn)
 {
@@ -1024,6 +1043,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 	int nid;
 	int ret;
 	struct memory_notify arg;
+	int zone_shift = 0;
 
 	/*
 	 * This doesn't need a lock to do pfn_to_page().
@@ -1038,18 +1058,16 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 		return -EINVAL;
 
 	if (online_type == MMOP_ONLINE_KERNEL &&
-	    zone_idx(zone) == ZONE_MOVABLE) {
-		if (move_pfn_range_left(zone - 1, zone, pfn, pfn + nr_pages))
-			return -EINVAL;
-	}
+	    zone_idx(zone) == ZONE_MOVABLE)
+		zone_shift = -1;
+
 	if (online_type == MMOP_ONLINE_MOVABLE &&
-	    zone_idx(zone) == ZONE_MOVABLE - 1) {
-		if (move_pfn_range_right(zone, zone + 1, pfn, pfn + nr_pages))
-			return -EINVAL;
-	}
+	    zone_idx(zone) == ZONE_MOVABLE - 1)
+		zone_shift = 1;
 
-	/* Previous code may changed the zone of the pfn range */
-	zone = page_zone(pfn_to_page(pfn));
+	zone = move_pfn_range(zone_shift, pfn, pfn + nr_pages);
+	if (!zone)
+		return -EINVAL;
 
 	arg.start_pfn = pfn;
 	arg.nr_pages = nr_pages;
-- 
1.8.3.1