From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx105.postini.com [74.125.245.105]) by kanga.kvack.org (Postfix) with SMTP id 7EAF46B0031 for ; Fri, 9 Aug 2013 01:53:39 -0400 (EDT) Message-ID: <5204838E.1060602@cn.fujitsu.com> Date: Fri, 09 Aug 2013 13:52:14 +0800 From: Tang Chen MIME-Version: 1.0 Subject: Re: [PATCH] mm/hotplug: Verify hotplug memory range References: <1375980460-28311-1-git-send-email-toshi.kani@hp.com> In-Reply-To: <1375980460-28311-1-git-send-email-toshi.kani@hp.com> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, dave@sr71.net, isimatu.yasuaki@jp.fujitsu.com, vasilis.liaskovitis@profitbricks.com On 08/09/2013 12:47 AM, Toshi Kani wrote: > 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 > --- > mm/memory_hotplug.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index ca1dd3a..ac182de 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("Unsupported hotplug range: start 0x%llx, size 0x%llx\n", > + start, size); I think the message here should tell users that only support range aligned to section. Others seems OK to me. Reviewed-by: Tang Chen Thanks. > + 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