linux-kernel - Re: [PATCH v2 0/3] Support memory hot-delete to boot memory

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Message-ID: <1365454703.32127.8.camel@misato.fc.hp.com>
Date:	Mon, 08 Apr 2013 14:58:23 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linuxram@...ibm.com, guz.fnst@...fujitsu.com, tmac@...com,
	isimatu.yasuaki@...fujitsu.com, wency@...fujitsu.com,
	tangchen@...fujitsu.com, jiang.liu@...wei.com
Subject: Re: [PATCH v2 0/3] Support memory hot-delete to boot memory

On Mon, 2013-04-08 at 13:44 -0700, Andrew Morton wrote:
> On Mon,  8 Apr 2013 11:09:53 -0600 Toshi Kani <toshi.kani@...com> wrote:
> 
> > Memory hot-delete to a memory range present at boot causes an
> > error message in __release_region(), such as:
> > 
> >  Trying to free nonexistent resource <0000000070000000-0000000077ffffff>
> > 
> > Hot-delete operation still continues since __release_region() is 
> > a void function, but the target memory range is not freed from
> > iomem_resource as the result.  This also leads a failure in a 
> > subsequent hot-add operation to the same memory range since the
> > address range is still in-use in iomem_resource.
> > 
> > This problem happens because the granularity of memory resource ranges
> > may be different between boot and hot-delete.
> 
> So we don't need this new code if CONFIG_MEMORY_HOTPLUG=n?  If so, can
> we please arrange for it to not be present if the user doesn't need it?

Good point!  Yes, since the new function is intended for memory
hot-delete and is only called from __remove_pages() in
mm/memory_hotplug.c, it should be added as #ifdef CONFIG_MEMORY_HOTPLUG
in PATCH 2/3.

I will make the change, and send an updated patch to PATCH 2/3.

Thanks,
-Toshi

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