Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754135Ab2JETdo (ORCPT ); Fri, 5 Oct 2012 15:33:44 -0400 Received: from mail-ob0-f174.google.com ([209.85.214.174]:54966 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751636Ab2JETdl (ORCPT ); Fri, 5 Oct 2012 15:33:41 -0400 MIME-Version: 1.0 In-Reply-To: <506E451E.1050403@jp.fujitsu.com> References: <506E43E0.70507@jp.fujitsu.com> <506E451E.1050403@jp.fujitsu.com> From: KOSAKI Motohiro Date: Fri, 5 Oct 2012 15:27:47 -0400 X-Google-Sender-Auth: qeWi1XyBECpJIlM4Y04FG5BmsSQ Message-ID: Subject: Re: [PATCH 1/10] memory-hotplug : check whether memory is offline or not when removing memory To: Yasuaki Ishimatsu Cc: 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, wency@cn.fujitsu.com 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: 5875 Lines: 157 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. > 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/