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Date: Wed, 27 Nov 2002 08:25:56 -0700
From: Matt Porter <porter@cox.net>
To: "David S. Miller" <davem@redhat.com>
Cc: Matt Porter <porter@cox.net>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][2.4] update ref counts on all allocated pages
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In-Reply-To: <1038393091.14825.0.camel@rth.ninka.net>; from davem@redhat.com on Wed, Nov 27, 2002 at 02:31:31AM -0800
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On Wed, Nov 27, 2002 at 02:31:31AM -0800, David S. Miller wrote:
> On Tue, 2002-11-26 at 16:07, Matt Porter wrote:
> > The following patch sets the ref count on all pages of an
> > allocation.  This allows an allocation with order>0 to be freed
> > via individual __free_page() calls within vfree().
> 
> If your pci_alloc_consistent implementation is doing something
> strang, _it_ should be doing the per-page reference counts.
> 
> Don't make every caller eat this overhead.

I'm surprised that's the recommended solution.  It seems pretty
dangerous to have allocated pages in the system where the per-page
ref counts are bogus.

To clarify then, on an order>0 allocation, it is only valid/defined
to free the same order of pages.  Is that a true statement?  If so,
I'll submit a docs patch and adjust our our local implementation.

Thanks,
-- 
Matt Porter
porter@cox.net
This is Linux Country. On a quiet night, you can hear Windows reboot.
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