Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751870Ab2F1F0n (ORCPT ); Thu, 28 Jun 2012 01:26:43 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:48499 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751315Ab2F1F0l convert rfc822-to-8bit (ORCPT ); Thu, 28 Jun 2012 01:26:41 -0400 MIME-Version: 1.0 In-Reply-To: <4FEA9DB1.7010303@jp.fujitsu.com> References: <4FEA9C88.1070800@jp.fujitsu.com> <4FEA9DB1.7010303@jp.fujitsu.com> From: KOSAKI Motohiro Date: Thu, 28 Jun 2012 01:26:21 -0400 X-Google-Sender-Auth: Y18m_kKX9oj5-uF4wFT7hBHiGDE Message-ID: Subject: Re: [RFC PATCH 2/12] memory-hogplug : check memory offline in offline_pages To: Yasuaki Ishimatsu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, wency@cn.fujitsu.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4593 Lines: 116 On Wed, Jun 27, 2012 at 1:44 AM, Yasuaki Ishimatsu wrote: > When offline_pages() is called to offlined memory, the function fails since > all memory has been offlined. In this case, the function should succeed. > The patch adds the check function into offline_pages(). I don't understand your point. I think following misoperation should fail. Otherwise administrator have no way to know their fault. $ echo offline > memoryN/state $ echo offline > memoryN/state In general, we don't like to ignore an error except the standard require it. > > 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 > > --- > ?drivers/base/memory.c ?| ? 20 ++++++++++++++++++++ > ?include/linux/memory.h | ? ?1 + > ?mm/memory_hotplug.c ? ?| ? ?5 +++++ > ?3 files changed, 26 insertions(+) > > Index: linux-3.5-rc4/drivers/base/memory.c > =================================================================== > --- linux-3.5-rc4.orig/drivers/base/memory.c ? ?2012-06-26 13:28:16.726211752 +0900 > +++ linux-3.5-rc4/drivers/base/memory.c 2012-06-26 13:34:22.423639904 +0900 > @@ -70,6 +70,26 @@ void unregister_memory_isolate_notifier( > ?} > ?EXPORT_SYMBOL(unregister_memory_isolate_notifier); > > +bool memory_is_offline(unsigned long start_pfn, unsigned long end_pfn) I dislike this function name. 'memory' is too vague to me. > +{ > + ? ? ? struct memory_block *mem; > + ? ? ? struct mem_section *section; > + ? ? ? unsigned long pfn, section_nr; > + > + ? ? ? for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { > + ? ? ? ? ? ? ? section_nr = pfn_to_section_nr(pfn); > + ? ? ? ? ? ? ? section = __nr_to_section(section_nr); > + ? ? ? ? ? ? ? mem = find_memory_block(section); This seems to have strong sparse dependency. Hm, I wonder why memory-hotplug.c can enable when X86_64_ACPI_NUMA. # eventually, we can have this option just 'select SPARSEMEM' config MEMORY_HOTPLUG bool "Allow for memory hot-add" depends on SPARSEMEM || X86_64_ACPI_NUMA > + ? ? ? ? ? ? ? if (!mem) > + ? ? ? ? ? ? ? ? ? ? ? continue; > + ? ? ? ? ? ? ? if (mem->state == MEM_OFFLINE) > + ? ? ? ? ? ? ? ? ? ? ? continue; > + ? ? ? ? ? ? ? return false; > + ? ? ? } > + > + ? ? ? return true; > +} > + > ?/* > ?* register_memory - Setup a sysfs device for a memory block > ?*/ > Index: linux-3.5-rc4/include/linux/memory.h > =================================================================== > --- linux-3.5-rc4.orig/include/linux/memory.h ? 2012-06-25 04:53:04.000000000 +0900 > +++ linux-3.5-rc4/include/linux/memory.h ? ? ? ?2012-06-26 13:34:22.424639891 +0900 > @@ -120,6 +120,7 @@ extern int memory_isolate_notify(unsigne > ?extern struct memory_block *find_memory_block_hinted(struct mem_section *, > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct memory_block *); > ?extern struct memory_block *find_memory_block(struct mem_section *); > +extern bool memory_is_offline(unsigned long start_pfn, unsigned long end_pfn); > ?#define CONFIG_MEM_BLOCK_SIZE ?(PAGES_PER_SECTION< ?enum mem_add_context { BOOT, HOTPLUG }; > ?#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ > Index: linux-3.5-rc4/mm/memory_hotplug.c > =================================================================== > --- linux-3.5-rc4.orig/mm/memory_hotplug.c ? ? ?2012-06-26 13:28:16.743211538 +0900 > +++ linux-3.5-rc4/mm/memory_hotplug.c ? 2012-06-26 13:48:38.264940468 +0900 > @@ -887,6 +887,11 @@ static int __ref offline_pages(unsigned > > ? ? ? ?lock_memory_hotplug(); > > + ? ? ? if (memory_is_offline(start_pfn, end_pfn)) { > + ? ? ? ? ? ? ? ret = 0; > + ? ? ? ? ? ? ? goto out; > + ? ? ? } > + > ? ? ? ?zone = page_zone(pfn_to_page(start_pfn)); > ? ? ? ?node = zone_to_nid(zone); > ? ? ? ?nr_pages = end_pfn - start_pfn; > > -- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/