Re: memory-hotplug : suppres "Trying to free nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>" warning
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-10-05 21:09:40
Also in:
linux-mm, linuxppc-dev
On Thu, 4 Oct 2012 14:31:09 +0900 Yasuaki Ishimatsu [off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>" 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>