On Wed, Oct 24, 2012 at 12:43 PM, Lai Jiangshan [off-list ref] 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 <redacted>
CC: KOSAKI Motohiro <redacted>
CC: Yasuaki Ishimatsu <redacted>
CC: Rob Landley <redacted>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Jiang Liu <redacted>
CC: Kay Sievers <redacted>
CC: Greg Kroah-Hartman <gregkh@suse.de>
CC: Mel Gorman <mgorman@suse.de>
CC: 'FNST-Wen Congyang' <redacted>
CC: linux-doc@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: linux-mm@kvack.org
Signed-off-by: Lai Jiangshan <redacted>

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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