linux-kernel - [PATCH 2/2 V2] slub, hotplug: ignore unrelated node's hot-adding and hot-removing

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Message-Id: <1351071840-5060-3-git-send-email-laijs@cn.fujitsu.com>
Date:	Wed, 24 Oct 2012 17:43:52 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	linux-kernel@...r.kernel.org
Cc:	Lai Jiangshan <laijs@...fujitsu.com>,
	David Rientjes <rientjes@...gle.com>,
	Minchan Kim <minchan.kim@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Rob Landley <rob@...dley.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiang Liu <jiang.liu@...wei.com>,
	Kay Sievers <kay.sievers@...y.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Mel Gorman <mgorman@...e.de>,
	"'FNST-Wen Congyang'" <wency@...fujitsu.com>,
	linux-doc@...r.kernel.org, linux-mm@...ck.org,
	Christoph Lameter <cl@...ux-foundation.org>,
	Pekka Enberg <penberg@...nel.org>,
	Matt Mackall <mpm@...enic.com>
Subject: [PATCH 2/2 V2] slub, hotplug: ignore unrelated node's hot-adding and hot-removing

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@...gle.com>
Cc: Minchan Kim <minchan.kim@...il.com>
CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
CC: Rob Landley <rob@...dley.net>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: Jiang Liu <jiang.liu@...wei.com>
CC: Kay Sievers <kay.sievers@...y.org>
CC: Greg Kroah-Hartman <gregkh@...e.de>
CC: Mel Gorman <mgorman@...e.de>
CC: 'FNST-Wen Congyang' <wency@...fujitsu.com>
CC: linux-doc@...r.kernel.org
CC: linux-kernel@...r.kernel.org
CC: linux-mm@...ck.org
Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
---
 mm/slub.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index a0d6984..487f0bd 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3573,7 +3573,7 @@ static void slab_mem_offline_callback(void *arg)
 	struct memory_notify *marg = arg;
 	int offline_node;
 
-	offline_node = marg->status_change_nid;
+	offline_node = marg->status_change_nid_normal;
 
 	/*
 	 * If the node still has available memory. we need kmem_cache_node
@@ -3606,7 +3606,7 @@ static int slab_mem_going_online_callback(void *arg)
 	struct kmem_cache_node *n;
 	struct kmem_cache *s;
 	struct memory_notify *marg = arg;
-	int nid = marg->status_change_nid;
+	int nid = marg->status_change_nid_normal;
 	int ret = 0;
 
 	/*
-- 
1.7.4.4

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