linux-kernel - Re: [PATCH] mm/hotplug: Verify hotplug memory range

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Date:	Thu, 08 Aug 2013 13:59:10 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>, dave@...1.net,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Tang Chen <tangchen@...fujitsu.com>,
	"vasilis.liaskovitis" <vasilis.liaskovitis@...fitbricks.com>
Subject: Re: [PATCH] mm/hotplug: Verify hotplug memory range

On Thu, 2013-08-08 at 15:53 -0400, KOSAKI Motohiro wrote:
> On Thu, Aug 8, 2013 at 12:47 PM, Toshi Kani <toshi.kani@...com> 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 <toshi.kani@...com>
> > ---
> >  mm/memory_hotplug.c |   22 ++++++++++++++++++++++
> 
> memory_hotplug.c is maintained by me and kamezawa-san. Please cc us
> if you have a subsequent patch.

Oh, I see.  Sorry about that.  Yes, I will copy you two from the next
time. 

> Acked-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>

Thanks!
-Toshi

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