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Date: Wed, 31 Oct 2012 09:09:58 +0200
Message-ID: <CAOJsxLFm3UXqz12_0kAXq7f+BkNAwY1a=rExgZTweD1dkT4yJg@mail.gmail.com>
Subject: Re: [PATCH 2/2 V2] slub, hotplug: ignore unrelated node's hot-adding
 and hot-removing
From: Pekka Enberg <penberg@kernel.org>
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To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: linux-kernel@vger.kernel.org, David Rientjes <rientjes@google.com>, Minchan Kim <minchan.kim@gmail.com>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>, Rob Landley <rob@landley.net>, Andrew Morton <akpm@linux-foundation.org>, Jiang Liu <jiang.liu@huawei.com>, Kay Sievers <kay.sievers@vrfy.org>, Greg Kroah-Hartman <gregkh@suse.de>, Mel Gorman <mgorman@suse.de>, FNST-Wen Congyang <wency@cn.fujitsu.com>, linux-doc@vger.kernel.org, linux-mm@kvack.org, Christoph Lameter <cl@linux-foundation.org>, Matt Mackall <mpm@selenic.com>

On Wed, Oct 24, 2012 at 12:43 PM, Lai Jiangshan <laijs@cn.fujitsu.com> 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@google.com>
> Cc: Minchan Kim <minchan.kim@gmail.com>
> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> CC: Rob Landley <rob@landley.net>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: Jiang Liu <jiang.liu@huawei.com>
> CC: Kay Sievers <kay.sievers@vrfy.org>
> CC: Greg Kroah-Hartman <gregkh@suse.de>
> CC: Mel Gorman <mgorman@suse.de>
> CC: 'FNST-Wen Congyang' <wency@cn.fujitsu.com>
> CC: linux-doc@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> CC: linux-mm@kvack.org
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>

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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