Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758690Ab2JSKjI (ORCPT ); Fri, 19 Oct 2012 06:39:08 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:14527 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751150Ab2JSKjD (ORCPT ); Fri, 19 Oct 2012 06:39:03 -0400 X-IronPort-AV: E=Sophos;i="4.80,612,1344182400"; d="scan'208";a="6031215" Message-ID: <50812F13.20503@cn.fujitsu.com> Date: Fri, 19 Oct 2012 18:44:35 +0800 From: Wen Congyang User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: KOSAKI Motohiro CC: Yasuaki Ishimatsu , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, sparclinux@vger.kernel.org, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org Subject: Re: [PATCH 1/10] memory-hotplug : check whether memory is offline or not when removing memory References: <506E43E0.70507@jp.fujitsu.com> <506E451E.1050403@jp.fujitsu.com> In-Reply-To: X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/10/19 18:38:33, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/10/19 18:38:35, Serialize complete at 2012/10/19 18:38:35 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6200 Lines: 167 At 10/06/2012 03:27 AM, KOSAKI Motohiro Wrote: > On Thu, Oct 4, 2012 at 10:25 PM, Yasuaki Ishimatsu > wrote: >> When calling remove_memory(), the memory should be offline. If the function >> is used to online memory, kernel panic may occur. >> >> So the patch checks whether memory is offline or not. > > You don't explain WHY we need the check. This patch is no necessary now, because the newest kernel has checked it. Thanks Wen Congyang > > >> CC: David Rientjes >> CC: Jiang Liu >> CC: Len Brown >> CC: Christoph Lameter >> Cc: Minchan Kim >> CC: Andrew Morton >> CC: KOSAKI Motohiro >> Signed-off-by: Wen Congyang >> Signed-off-by: Yasuaki Ishimatsu >> >> --- >> drivers/base/memory.c | 39 +++++++++++++++++++++++++++++++++++++++ >> include/linux/memory.h | 5 +++++ >> mm/memory_hotplug.c | 17 +++++++++++++++-- >> 3 files changed, 59 insertions(+), 2 deletions(-) >> >> Index: linux-3.6/drivers/base/memory.c >> =================================================================== >> --- linux-3.6.orig/drivers/base/memory.c 2012-10-04 14:22:57.000000000 +0900 >> +++ linux-3.6/drivers/base/memory.c 2012-10-04 14:45:46.653585860 +0900 >> @@ -70,6 +70,45 @@ void unregister_memory_isolate_notifier( >> } >> EXPORT_SYMBOL(unregister_memory_isolate_notifier); >> >> +bool is_memblk_offline(unsigned long start, unsigned long size) > > Don't use memblk. Usually memblk mean struct numa_meminfo for x86/numa. > Maybe memory_range_offlined() is better. > > And, this function don't take struct memory_block, then this file may be no good > place. > > And you need to write down function comment. > > >> +{ >> + struct memory_block *mem = NULL; >> + struct mem_section *section; >> + unsigned long start_pfn, end_pfn; >> + unsigned long pfn, section_nr; >> + >> + start_pfn = PFN_DOWN(start); >> + end_pfn = PFN_UP(start + size); >> + >> + for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { >> + section_nr = pfn_to_section_nr(pfn); >> + if (!present_section_nr(section_nr)) >> + continue; >> + >> + section = __nr_to_section(section_nr); >> + /* same memblock? */ >> + if (mem) >> + if ((section_nr >= mem->start_section_nr) && >> + (section_nr <= mem->end_section_nr)) >> + continue; >> + >> + mem = find_memory_block_hinted(section, mem); >> + if (!mem) >> + continue; >> + if (mem->state == MEM_OFFLINE) >> + continue; >> + >> + kobject_put(&mem->dev.kobj); >> + return false; >> + } >> + >> + if (mem) >> + kobject_put(&mem->dev.kobj); >> + >> + return true; >> +} >> +EXPORT_SYMBOL(is_memblk_offline); >> + >> /* >> * register_memory - Setup a sysfs device for a memory block >> */ >> Index: linux-3.6/include/linux/memory.h >> =================================================================== >> --- linux-3.6.orig/include/linux/memory.h 2012-10-02 18:00:22.000000000 +0900 >> +++ linux-3.6/include/linux/memory.h 2012-10-04 14:44:40.902581028 +0900 >> @@ -106,6 +106,10 @@ static inline int memory_isolate_notify( >> { >> return 0; >> } >> +static inline bool is_memblk_offline(unsigned long start, unsigned long size) >> +{ >> + return false; >> +} >> #else >> extern int register_memory_notifier(struct notifier_block *nb); >> extern void unregister_memory_notifier(struct notifier_block *nb); >> @@ -120,6 +124,7 @@ 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 is_memblk_offline(unsigned long start, unsigned long size); >> #define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<> enum mem_add_context { BOOT, HOTPLUG }; >> #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */ >> Index: linux-3.6/mm/memory_hotplug.c >> =================================================================== >> --- linux-3.6.orig/mm/memory_hotplug.c 2012-10-04 14:31:08.000000000 +0900 >> +++ linux-3.6/mm/memory_hotplug.c 2012-10-04 14:58:22.449687986 +0900 >> @@ -1045,8 +1045,21 @@ int offline_memory(u64 start, u64 size) >> >> int remove_memory(int nid, u64 start, u64 size) >> { > > Your remove_memory() don't remove anything. that's strange. > > >> - /* It is not implemented yet*/ >> - return 0; >> + int ret = 0; >> + lock_memory_hotplug(); >> + /* >> + * The memory might become online by other task, even if you offine it. >> + * So we check whether the memory has been onlined or not. >> + */ >> + if (!is_memblk_offline(start, size)) { >> + pr_warn("memory removing [mem %#010llx-%#010llx] failed, " >> + "because the memmory range is online\n", >> + start, start + size); > > No good warning. You should output which memory block can't be > offlined, I think. > > >> + ret = -EAGAIN; >> + } >> + >> + unlock_memory_hotplug(); >> + return ret; >> } >> EXPORT_SYMBOL_GPL(remove_memory); >> #else >> >> -- >> 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/