From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx161.postini.com [74.125.245.161]) by kanga.kvack.org (Postfix) with SMTP id 05A0B6B0031 for ; Sat, 10 Aug 2013 15:18:57 -0400 (EDT) From: Toshi Kani Subject: [PATCH v2] mm/hotplug: Verify hotplug memory range Date: Sat, 10 Aug 2013 13:17:32 -0600 Message-Id: <1376162252-26074-1-git-send-email-toshi.kani@hp.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kosaki.motohiro@jp.fujitsu.com, kamezawa.hiroyu@jp.fujitsu.com, dave@sr71.net, isimatu.yasuaki@jp.fujitsu.com, tangchen@cn.fujitsu.com, vasilis.liaskovitis@profitbricks.com, Toshi Kani add_memory() and remove_memory() can only handle a memory range aligned with section. There are problems when an unaligned range is added and then deleted as follows: - add_memory() with an unaligned range succeeds, but __add_pages() called from add_memory() adds a whole section of pages even though a given memory range is less than the section size. - remove_memory() to the added unaligned range hits BUG_ON() in __remove_pages(). This patch changes add_memory() and remove_memory() to check if a given memory range is aligned with section at the beginning. As the result, add_memory() fails with -EINVAL when a given range is unaligned, and does not add such memory range. This prevents remove_memory() to be called with an unaligned range as well. Note that remove_memory() has to use BUG_ON() since this function cannot fail. Signed-off-by: Toshi Kani Acked-by: KOSAKI Motohiro Reviewed-by: Tang Chen --- v2: Updated the error message. --- mm/memory_hotplug.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index ca1dd3a..3bb1f39 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1069,6 +1069,22 @@ out: return ret; } +static int check_hotplug_memory_range(u64 start, u64 size) +{ + u64 start_pfn = start >> PAGE_SHIFT; + u64 nr_pages = size >> PAGE_SHIFT; + + /* Memory range must be aligned with section */ + if ((start_pfn & ~PAGE_SECTION_MASK) || + (nr_pages % PAGES_PER_SECTION) || (!nr_pages)) { + pr_err("Section-unaligned hotplug range: start 0x%llx, size 0x%llx\n", + start, size); + return -EINVAL; + } + + return 0; +} + /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */ int __ref add_memory(int nid, u64 start, u64 size) { @@ -1078,6 +1094,10 @@ int __ref add_memory(int nid, u64 start, u64 size) struct resource *res; int ret; + ret = check_hotplug_memory_range(start, size); + if (ret) + return ret; + lock_memory_hotplug(); res = register_memory_resource(start, size); @@ -1786,6 +1806,8 @@ void __ref remove_memory(int nid, u64 start, u64 size) { int ret; + BUG_ON(check_hotplug_memory_range(start, size)); + lock_memory_hotplug(); /* -- 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