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Date: Thu, 08 Oct 2009 14:12:13 +0200
From: Gerald Schaefer <geralds@linux.vnet.ibm.com>
MIME-Version: 1.0
To: Robert Jennings <rcj@linux.vnet.ibm.com>
Subject: Re: [PATCH 2/2][v2] powerpc: Make the CMM memory hotplug aware
References: <20091002184458.GC4908@austin.ibm.com>
	<20091002185248.GD4908@austin.ibm.com>
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Cc: linux-mm@kvack.org, Mel Gorman <mel@csn.ul.ie>,
	linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Badari Pulavarty <pbadari@us.ibm.com>,
	Brian King <brking@linux.vnet.ibm.com>,
	Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@elte.hu>
Reply-To: gerald.schaefer@de.ibm.com
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Hi,

I am currently working on the s390 port for the cmm + hotplug
patch, and I'm a little confused about the memory allocation
policy, see below. Is it correct that the balloon cannot grow
into ZONE_MOVABLE, while the pages for the balloon page list
can?

Robert Jennings wrote:
> @@ -110,6 +125,9 @@ static long cmm_alloc_pages(long nr)
>  	cmm_dbg("Begin request for %ld pages\n", nr);
> 
>  	while (nr) {
> +		if (atomic_read(&hotplug_active))
> +			break;
> +
>  		addr = __get_free_page(GFP_NOIO | __GFP_NOWARN |
>  				       __GFP_NORETRY | __GFP_NOMEMALLOC);
>  		if (!addr)
> @@ -119,8 +137,10 @@ static long cmm_alloc_pages(long nr)
>  		if (!pa || pa->index >= CMM_NR_PAGES) {
>  			/* Need a new page for the page list. */
>  			spin_unlock(&cmm_lock);
> -			npa = (struct cmm_page_array *)__get_free_page(GFP_NOIO | __GFP_NOWARN |
> -								       __GFP_NORETRY | __GFP_NOMEMALLOC);
> +			npa = (struct cmm_page_array *)__get_free_page(
> +					GFP_NOIO | __GFP_NOWARN |
> +					__GFP_NORETRY | __GFP_NOMEMALLOC |
> +					__GFP_MOVABLE);
>  			if (!npa) {
>  				pr_info("%s: Can not allocate new page list\n", __func__);
>  				free_page(addr);

Why is the __GFP_MOVABLE added here, for the page list alloc, and not
above for the balloon page alloc?

--
Regards,
Gerald