From: Andrew Morton <akpm@linux-foundation.org>
To: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: qiuxishi <qiuxishi@gmail.com>,
mgorman@suse.de, tony.luck@intel.com,
Jiang Liu <jiang.liu@huawei.com>,
qiuxishi@huawei.com, bessel.wang@huawei.com,
wujianguo@huawei.com, paul.gortmaker@windriver.com,
kamezawa.hiroyu@jp.fujitsu.com, kosaki.motohiro@jp.fujitsu.com,
rientjes@google.com, Minchan Kim <minchan@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Wen Congyang <wency@cn.fujitsu.com>
Subject: Re: [PATCH RESEND] memory hotplug: fix a double register section info bug
Date: Fri, 14 Sep 2012 13:14:28 -0700 [thread overview]
Message-ID: <20120914131428.1f530681.akpm@linux-foundation.org> (raw)
In-Reply-To: <50530E39.5020100@jp.fujitsu.com>
On Fri, 14 Sep 2012 20:00:09 +0900
Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> wrote:
> > @@ -187,9 +184,10 @@ void register_page_bootmem_info_node(struct pglist_data *pgdat)
> > end_pfn = pfn + pgdat->node_spanned_pages;
> >
> > /* register_section info */
> > - for (; pfn < end_pfn; pfn += PAGES_PER_SECTION)
> > - register_page_bootmem_info_section(pfn);
> > -
> > + for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> > + if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
>
> I cannot judge whether your configuration is correct or not.
> Thus if it is correct, I want a comment of why the node check is
> needed. In usual configuration, a node does not span the other one.
> So it is natural that "pfn_to_nid(pfn) is same as "pgdat->node_id".
> Thus we may remove the node check in the future.
yup. How does this look?
--- a/mm/memory_hotplug.c~memory-hotplug-fix-a-double-register-section-info-bug-fix
+++ a/mm/memory_hotplug.c
@@ -185,6 +185,12 @@ void register_page_bootmem_info_node(str
/* register_section info */
for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ /*
+ * Some platforms can assign the same pfn to multiple nodes - on
+ * node0 as well as nodeN. To avoid registering a pfn against
+ * multiple nodes we check that this pfn does not already
+ * reside in some other node.
+ */
if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
register_page_bootmem_info_section(pfn);
}
_
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next prev parent reply other threads:[~2012-09-14 20:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-14 3:43 [PATCH RESEND] memory hotplug: fix a double register section info bug qiuxishi
2012-09-14 9:52 ` Mel Gorman
2012-09-14 16:24 ` Luck, Tony
2012-09-17 14:21 ` Mel Gorman
2012-09-14 11:00 ` Yasuaki Ishimatsu
2012-09-14 20:14 ` Andrew Morton [this message]
2012-09-16 10:14 ` xishi qiu
2012-09-18 0:11 ` Yasuaki Ishimatsu
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