linux-kernel - [PATCH RFC 3/8] mm: use PG_offline in online/offlining code

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Date:   Fri, 13 Apr 2018 15:16:27 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-mm@...ck.org
Cc:     David Hildenbrand <david@...hat.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Pavel Tatashin <pasha.tatashin@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Johannes Weiner <hannes@...xchg.org>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        devel@...uxdriverproject.org (open list:Hyper-V CORE AND DRIVERS),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH RFC 3/8] mm: use PG_offline in online/offlining code

Let's mark all offline pages with PG_offline. We'll continue to mark
them reserved.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 drivers/hv/hv_balloon.c |  2 +-
 mm/memory_hotplug.c     | 10 ++++++----
 mm/page_alloc.c         |  5 ++++-
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index b3e9f13f8bc3..04d98d9b6191 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -893,7 +893,7 @@ static unsigned long handle_pg_range(unsigned long pg_start,
 			 * backed previously) online too.
 			 */
 			if (start_pfn > has->start_pfn &&
-			    !PageReserved(pfn_to_page(start_pfn - 1)))
+			    !PageOffline(pfn_to_page(start_pfn - 1)))
 				hv_bring_pgs_online(has, start_pfn, pgs_ol);
 
 		}
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d4474781c799..3a8d56476233 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -260,8 +260,8 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
 		return ret;
 
 	/*
-	 * Make all the pages reserved so that nobody will stumble over half
-	 * initialized state.
+	 * Make all the pages offline and reserved so that nobody will stumble
+	 * over half initialized state.
 	 * FIXME: We also have to associate it with a node because page_to_nid
 	 * relies on having page with the proper node.
 	 */
@@ -274,6 +274,7 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
 		page = pfn_to_page(pfn);
 		set_page_node(page, nid);
 		SetPageReserved(page);
+		SetPageOffline(page);
 	}
 
 	if (!want_memblock)
@@ -669,6 +670,7 @@ EXPORT_SYMBOL_GPL(__online_page_increment_counters);
 
 void __online_page_free(struct page *page)
 {
+	ClearPageOffline(page);
 	__free_reserved_page(page);
 }
 EXPORT_SYMBOL_GPL(__online_page_free);
@@ -687,7 +689,7 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 	unsigned long onlined_pages = *(unsigned long *)arg;
 	struct page *page;
 
-	if (PageReserved(pfn_to_page(start_pfn)))
+	if (PageOffline(pfn_to_page(start_pfn)))
 		for (i = 0; i < nr_pages; i++) {
 			page = pfn_to_page(start_pfn + i);
 			(*online_page_callback)(page);
@@ -1437,7 +1439,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 }
 
 /*
- * remove from free_area[] and mark all as Reserved.
+ * remove from free_area[] and mark all as Reserved and Offline.
  */
 static int
 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 647c8c6dd4d1..2e5dcfdb0908 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8030,6 +8030,7 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 		if (unlikely(!PageBuddy(page) && PageHWPoison(page))) {
 			pfn++;
 			SetPageReserved(page);
+			SetPageOffline(page);
 			continue;
 		}
 
@@ -8043,8 +8044,10 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 		list_del(&page->lru);
 		rmv_page_order(page);
 		zone->free_area[order].nr_free--;
-		for (i = 0; i < (1 << order); i++)
+		for (i = 0; i < (1 << order); i++) {
 			SetPageReserved((page+i));
+			SetPageOffline(page + i);
+		}
 		pfn += (1 << order);
 	}
 	spin_unlock_irqrestore(&zone->lock, flags);
-- 
2.14.3