Re: [PATCH 2/2 V2] slub, hotplug: ignore unrelated node's hot-addingand hot-removing

[Pekka Enberg]

On Wed, Oct 24, 2012 at 12:43 PM, Lai Jiangshan <laijs@xxxxxxxxxxxxxx> wrote:
> SLUB only fucus on the nodes which has normal memory, so ignore the other
> node's hot-adding and hot-removing.
>
> Aka: if some memroy of a node(which has no onlined memory) is online,
> but this new memory onlined is not normal memory(HIGH memory example),
> we should not allocate kmem_cache_node for SLUB.
>
> And if the last normal memory is offlined, but the node still has memroy,
> we should remove kmem_cache_node for that node.(current code delay it when
> all of the memory is offlined)
>
> so we only do something when marg->status_change_nid_normal > 0.
> marg->status_change_nid is not suitable here.
>
> The same problem doesn't exsit in SLAB, because SLAB allocates kmem_list3
> for every node even the node don't have normal memory, SLAB tolerates
> kmem_list3 on alien nodes. SLUB only fucus on the nodes which has normal
> memory, it don't tolerates alien kmem_cache_node, the patch makes
> SLUB become self-compatible and avoid WARN and BUG in a rare condition.
>
> CC: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
> CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> CC: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
> CC: Rob Landley <rob@xxxxxxxxxxx>
> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> CC: Jiang Liu <jiang.liu@xxxxxxxxxx>
> CC: Kay Sievers <kay.sievers@xxxxxxxx>
> CC: Greg Kroah-Hartman <gregkh@xxxxxxx>
> CC: Mel Gorman <mgorman@xxxxxxx>
> CC: 'FNST-Wen Congyang' <wency@xxxxxxxxxxxxxx>
> CC: linux-doc@xxxxxxxxxxxxxxx
> CC: linux-kernel@xxxxxxxxxxxxxxx
> CC: linux-mm@xxxxxxxxx
> Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>

The patch looks OK but changelog doesn't say what problem this fixes,
how you found about it, and do we need this in stable.
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