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

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Date:   Wed, 10 Apr 2019 22:24:13 +0000
From:   Wei Yang <richard.weiyang@...il.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        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: Re: [PATCH] mm/memory_hotplug: Drop memory device reference after
 find_memory_block()

On Wed, Apr 10, 2019 at 12:14:55PM +0200, David Hildenbrand wrote:
>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>

You are right.

Reviewed-by: Wei Yang <richard.weiyang@...il.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

-- 
Wei Yang
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