From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx127.postini.com [74.125.245.127]) by kanga.kvack.org (Postfix) with SMTP id C002B6B0033 for ; Fri, 9 Aug 2013 11:34:23 -0400 (EDT) Message-ID: <1376062391.10300.245.camel@misato.fc.hp.com> Subject: Re: [PATCH] mm/hotplug: Verify hotplug memory range From: Toshi Kani Date: Fri, 09 Aug 2013 09:33:11 -0600 In-Reply-To: <5204838E.1060602@cn.fujitsu.com> References: <1375980460-28311-1-git-send-email-toshi.kani@hp.com> <5204838E.1060602@cn.fujitsu.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Tang Chen 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 Fri, 2013-08-09 at 13:52 +0800, Tang Chen wrote: > 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. OK, I will change the message to something like this: pr_err("Section-unaligned hotplug range: start 0x%llx, size 0x%llx\n", start, size); > Reviewed-by: Tang Chen Thanks! -Toshi -- 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