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Date: Fri, 2 Mar 2007 04:49:10 +0000
From: Christoph Hellwig <hch@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>, support@coraid.com,
       "Ed L. Cashin" <ecashin@coraid.com>, linux-kernel@vger.kernel.org,
       Greg KH <greg@kroah.com>
Subject: Re: PATCH 2.6.21-rc1 aoe: handle zero _count pages in bios
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On Thu, Mar 01, 2007 at 08:48:06PM -0800, Andrew Morton wrote:
> On Fri, 2 Mar 2007 04:30:39 +0000 Christoph Hellwig <hch@infradead.org> wrote:
> 
> > But in this case we'd really need to enforce this, and add a
> > BUG_ON(PageSlab(page)) in bio_add_page to trip everyone submit
> > this kind of pages.
> 
> That would be
> 
> 	BUG_ON(PageSlab(page) && page_count(page) == 0)?

No, all slab pages.  Currently they all have a reference count of
zero, but we generally don't want people to pass in pages that
come from a non-refcounted allocator.