From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx102.postini.com [74.125.245.102]) by kanga.kvack.org (Postfix) with SMTP id E0ADD6B0082 for ; Wed, 18 Jul 2012 06:20:54 -0400 (EDT) Message-ID: <50068F0A.20100@cn.fujitsu.com> Date: Wed, 18 Jul 2012 18:25:14 +0800 From: Wen Congyang MIME-Version: 1.0 Subject: Re: [PATCH v4 3/13] memory-hotplug : check whether memory is present or not References: <50068974.1070409@jp.fujitsu.com> <50068AE9.3050804@jp.fujitsu.com> In-Reply-To: <50068AE9.3050804@jp.fujitsu.com> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-2022-JP Sender: owner-linux-mm@kvack.org List-ID: To: Yasuaki Ishimatsu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com At 07/18/2012 06:07 PM, Yasuaki Ishimatsu Wrote: > If system supports memory hot-remove, online_pages() may online removed pages. > So online_pages() need to check whether onlining pages are present or not. > > CC: David Rientjes > CC: Jiang Liu > CC: Len Brown > CC: Benjamin Herrenschmidt > CC: Paul Mackerras > CC: Christoph Lameter > Cc: Minchan Kim > CC: Andrew Morton > CC: KOSAKI Motohiro > CC: Wen Congyang > Signed-off-by: Yasuaki Ishimatsu > > --- > include/linux/mmzone.h | 21 +++++++++++++++++++++ > mm/memory_hotplug.c | 13 +++++++++++++ > 2 files changed, 34 insertions(+) > > Index: linux-3.5-rc6/include/linux/mmzone.h > =================================================================== > --- linux-3.5-rc6.orig/include/linux/mmzone.h 2012-07-08 09:23:56.000000000 +0900 > +++ linux-3.5-rc6/include/linux/mmzone.h 2012-07-17 16:10:21.588186145 +0900 > @@ -1168,6 +1168,27 @@ void sparse_init(void); > #define sparse_index_init(_sec, _nid) do {} while (0) > #endif /* CONFIG_SPARSEMEM */ > > +#ifdef CONFIG_SPARSEMEM > +static inline int pfns_present(unsigned long pfn, unsigned long nr_pages) > +{ > + int i; > + for (i = 0; i < nr_pages; i++) { > + if (pfn_present(pfn + 1)) > + continue; > + else { > + unlock_memory_hotplug(); Why do you unlock memory hotplug here? The caller will do it. Thanks Wen Congyang > + return -EINVAL; > + } > + } > + return 0; > +} > +#else > +static inline int pfns_present(unsigned long pfn, unsigned long nr_pages) > +{ > + return 0; > +} > +#endif /* CONFIG_SPARSEMEM*/ > + > #ifdef CONFIG_NODES_SPAN_OTHER_NODES > bool early_pfn_in_nid(unsigned long pfn, int nid); > #else > Index: linux-3.5-rc6/mm/memory_hotplug.c > =================================================================== > --- linux-3.5-rc6.orig/mm/memory_hotplug.c 2012-07-17 14:26:40.000000000 +0900 > +++ linux-3.5-rc6/mm/memory_hotplug.c 2012-07-17 16:09:50.070580170 +0900 > @@ -467,6 +467,19 @@ int __ref online_pages(unsigned long pfn > struct memory_notify arg; > > lock_memory_hotplug(); > + /* > + * If system supports memory hot-remove, the memory may have been > + * removed. So we check whether the memory has been removed or not. > + * > + * Note: When CONFIG_SPARSEMEM is defined, pfns_present() become > + * effective. If CONFIG_SPARSEMEM is not defined, pfns_present() > + * always returns 0. > + */ > + ret = pfns_present(pfn, nr_pages); > + if (ret) { > + unlock_memory_hotplug(); > + return ret; > + } > arg.start_pfn = pfn; > arg.nr_pages = nr_pages; > arg.status_change_nid = -1; > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org