linux-kernel - [PATCH] mm/memory_hotplug: Drop memory device reference after find_memory

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Date:   Wed, 10 Apr 2019 12:14:55 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, David Hildenbrand <david@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Oscar Salvador <osalvador@...e.de>,
        Michal Hocko <mhocko@...e.com>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Wei Yang <richard.weiyang@...il.com>, Qian Cai <cai@....pw>,
        Arun KS <arunks@...eaurora.org>,
        Mathieu Malaterre <malat@...ian.org>
Subject: [PATCH] mm/memory_hotplug: Drop memory device reference after find_memory_block()

While current node handling is probably terribly broken for memory block
devices that span several nodes (only possible when added during boot,
and something like that should be blocked completely), properly put the
device reference we obtained via find_memory_block() to get the nid.

Fixes: d0dc12e86b31 ("mm/memory_hotplug: optimize memory hotplug")
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Oscar Salvador <osalvador@...e.de>
Cc: Michal Hocko <mhocko@...e.com>
Cc: David Hildenbrand <david@...hat.com>
Cc: Pavel Tatashin <pasha.tatashin@...een.com>
Cc: Wei Yang <richard.weiyang@...il.com>
Cc: Qian Cai <cai@....pw>
Cc: Arun KS <arunks@...eaurora.org>
Cc: Mathieu Malaterre <malat@...ian.org>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/memory_hotplug.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 5eb4a4c7c21b..328878b6799d 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -854,6 +854,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
 	 */
 	mem = find_memory_block(__pfn_to_section(pfn));
 	nid = mem->nid;
+	put_device(&mem->dev);
 
 	/* associate pfn range with the zone */
 	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
-- 
2.20.1