From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx141.postini.com [74.125.245.141]) by kanga.kvack.org (Postfix) with SMTP id 0A5606B005A for ; Fri, 5 Oct 2012 17:09:40 -0400 (EDT) Date: Fri, 5 Oct 2012 14:09:38 -0700 From: Andrew Morton Subject: Re: memory-hotplug : suppres "Trying to free nonexistent resource " warning Message-Id: <20121005140938.e3e1e196.akpm@linux-foundation.org> In-Reply-To: <506D1F1D.9000301@jp.fujitsu.com> References: <506D1F1D.9000301@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: 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, 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 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. -- 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