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Date: Mon, 13 Oct 2003 01:11:17 -0700
From: Andrew Morton <akpm@osdl.org>
To: Zwane Mwaikambo <zwane@arm.linux.org.uk>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH][2.6] No swapping on memory backed swapfiles
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Zwane Mwaikambo <zwane@arm.linux.org.uk> wrote:
>
> +	bdi = mapping->backing_dev_info;
>  +	if (bdi->memory_backed)
>  +		goto bad_swap;
>  +

I guess that makes sense, although someone might want to swap onto a
ramdisk-backed file just for some testing purpose.

Why not simply test for a null ->readpage()?