From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx176.postini.com [74.125.245.176]) by kanga.kvack.org (Postfix) with SMTP id EB5836B002B for ; Mon, 8 Oct 2012 22:52:10 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 74DFE3EE0C0 for ; Tue, 9 Oct 2012 11:52:08 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 5AD8345DE53 for ; Tue, 9 Oct 2012 11:52:08 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 4170945DE4E for ; Tue, 9 Oct 2012 11:52:08 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 2C5661DB803E for ; Tue, 9 Oct 2012 11:52:08 +0900 (JST) Received: from g01jpexchyt06.g01.fujitsu.local (g01jpexchyt06.g01.fujitsu.local [10.128.194.45]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id B36FA1DB8040 for ; Tue, 9 Oct 2012 11:52:07 +0900 (JST) Message-ID: <5073913A.3080103@jp.fujitsu.com> Date: Tue, 9 Oct 2012 11:51:38 +0900 From: Yasuaki Ishimatsu MIME-Version: 1.0 Subject: Re: memory-hotplug : suppres "Trying to free nonexistent resource " warning References: <506D1F1D.9000301@jp.fujitsu.com> <20121005140938.e3e1e196.akpm@linux-foundation.org> In-Reply-To: <20121005140938.e3e1e196.akpm@linux-foundation.org> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: x86@kernel.org, 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, kosaki.motohiro@jp.fujitsu.com, wency@cn.fujitsu.com, dave@linux.vnet.ibm.com Hi Andrew, 2012/10/06 6:09, Andrew Morton wrote: > On Thu, 4 Oct 2012 14:31:09 +0900 > Yasuaki Ishimatsu wrote: > >> When our x86 box calls __remove_pages(), release_mem_region() shows >> many warnings. And x86 box cannot unregister iomem_resource. >> >> "Trying to free nonexistent resource " >> >> release_mem_region() has been changed as called in each PAGES_PER_SECTION >> chunk since applying a patch(de7f0cba96786c). Because powerpc registers >> iomem_resource in each PAGES_PER_SECTION chunk. But when I hot add memory >> on x86 box, iomem_resource is register in each _CRS not PAGES_PER_SECTION >> chunk. So x86 box unregisters iomem_resource. >> >> The patch fixes the problem. >> >> --- linux-3.6.orig/arch/powerpc/platforms/pseries/hotplug-memory.c 2012-10-04 14:22:59.833520792 +0900 >> +++ linux-3.6/arch/powerpc/platforms/pseries/hotplug-memory.c 2012-10-04 14:23:05.150521411 +0900 >> @@ -77,7 +77,8 @@ static int pseries_remove_memblock(unsig >> { >> unsigned long start, start_pfn; >> struct zone *zone; >> - int ret; >> + int i, ret; >> + int sections_to_remove; >> >> start_pfn = base >> PAGE_SHIFT; >> >> @@ -97,9 +98,13 @@ static int pseries_remove_memblock(unsig >> * to sysfs "state" file and we can't remove sysfs entries >> * while writing to it. So we have to defer it to here. >> */ >> - ret = __remove_pages(zone, start_pfn, memblock_size >> PAGE_SHIFT); >> - if (ret) >> - return ret; >> + sections_to_remove = (memblock_size >> PAGE_SHIFT) / PAGES_PER_SECTION; >> + for (i = 0; i < sections_to_remove; i++) { >> + unsigned long pfn = start_pfn + i * PAGES_PER_SECTION; >> + ret = __remove_pages(zone, start_pfn, PAGES_PER_SECTION); >> + if (ret) >> + return ret; >> + } > > It is inappropriate that `i' have a signed 32-bit type. I doubt if > there's any possibility of an overflow bug here, but using a consistent > and well-chosen type would eliminate all doubt. > > Note that __remove_pages() does use an unsigned long for this, although > it stupidly calls that variable "i", despite the C programmers' > expectation that a variable called "i" has type "int". > > The same applies to `sections_to_remove', but __remove_pages() went and > decided to use an `int' for that variable. Sigh. > > Anyway, please have a think, and see if we can come up with the best > and most accurate choice of types and identifiers in this code. Your concern is right. Overflow bug may occur in the future. So I changed type of "i" and "sections_to_remove" to "unsigned long". Please merge it into your tree instead of previous patch. __remove_pages() also has same concern. So I'll fix it. ----------------------------------------------------------------------- When our x86 box calls __remove_pages(), release_mem_region() shows many warnings. And x86 box cannot unregister iomem_resource. "Trying to free nonexistent resource " release_mem_region() has been changed as called in each PAGES_PER_SECTION chunk since applying a patch(de7f0cba96786c). Because powerpc registers iomem_resource in each PAGES_PER_SECTION chunk. But when I hot add memory on x86 box, iomem_resource is register in each _CRS not PAGES_PER_SECTION chunk. So x86 box unregisters iomem_resource. The patch fixes the problem. 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 --- arch/powerpc/platforms/pseries/hotplug-memory.c | 11 ++++++++--- mm/memory_hotplug.c | 4 ++-- 2 files changed, 10 insertions(+), 5 deletions(-) Index: linux-3.6/arch/powerpc/platforms/pseries/hotplug-memory.c =================================================================== --- linux-3.6.orig/arch/powerpc/platforms/pseries/hotplug-memory.c 2012-10-05 14:33:09.516197839 +0900 +++ linux-3.6/arch/powerpc/platforms/pseries/hotplug-memory.c 2012-10-09 11:27:50.555709827 +0900 @@ -78,6 +78,7 @@ static int pseries_remove_memblock(unsig unsigned long start, start_pfn; struct zone *zone; int ret; + unsigned long i, sections_to_remove; start_pfn = base >> PAGE_SHIFT; @@ -97,9 +98,13 @@ static int pseries_remove_memblock(unsig * to sysfs "state" file and we can't remove sysfs entries * while writing to it. So we have to defer it to here. */ - ret = __remove_pages(zone, start_pfn, memblock_size >> PAGE_SHIFT); - if (ret) - return ret; + sections_to_remove = (memblock_size >> PAGE_SHIFT) / PAGES_PER_SECTION; + for (i = 0; i < sections_to_remove; i++) { + unsigned long pfn = start_pfn + i * PAGES_PER_SECTION; + ret = __remove_pages(zone, start_pfn, PAGES_PER_SECTION); + if (ret) + return ret; + } /* * Update memory regions for memory remove Index: linux-3.6/mm/memory_hotplug.c =================================================================== --- linux-3.6.orig/mm/memory_hotplug.c 2012-10-05 15:21:42.856325965 +0900 +++ linux-3.6/mm/memory_hotplug.c 2012-10-05 15:21:43.047326148 +0900 @@ -596,11 +596,11 @@ int __remove_pages(struct zone *zone, un BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK); BUG_ON(nr_pages % PAGES_PER_SECTION); + release_mem_region(phys_start_pfn << PAGE_SHIFT, nr_pages * PAGE_SIZE); + sections_to_remove = nr_pages / PAGES_PER_SECTION; for (i = 0; i < sections_to_remove; i++) { unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION; - release_mem_region(pfn << PAGE_SHIFT, - PAGES_PER_SECTION << PAGE_SHIFT); ret = __remove_section(zone, __pfn_to_section(pfn)); if (ret) break; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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