Re: [PATCH] mm/memory_hotplug: Drop memory device reference after find_memory_block()

From: Wei Yang
Date: Wed Apr 10 2019 - 18:24:18 EST

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@xxxxxxxxxxxxxxxxxxxx>
>Cc: Oscar Salvador <osalvador@xxxxxxx>
>Cc: Michal Hocko <mhocko@xxxxxxxx>
>Cc: David Hildenbrand <david@xxxxxxxxxx>
>Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
>Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
>Cc: Qian Cai <cai@xxxxxx>
>Cc: Arun KS <arunks@xxxxxxxxxxxxxx>
>Cc: Mathieu Malaterre <malat@xxxxxxxxxx>
>Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>

You are right.

Reviewed-by: Wei Yang <richard.weiyang@xxxxxxxxx>

> 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);

Wei Yang
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