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Date:   Wed, 21 Feb 2018 15:44:10 +0100
From:   Jonathan =?utf-8?Q?Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>
To:     Jonathan =?utf-8?Q?Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>
Cc:     christophe leroy <christophe.leroy@c-s.fr>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Michael Ellerman <mpe@ellerman.id.au>, linux-mm@kvack.org,
        Joel Stanley <joel@jms.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Balbir Singh <bsingharora@gmail.com>,
        Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH 1/6] powerpc/mm/32: Use pfn_valid to check if pointer is
 in RAM
Message-ID: <20180221144410.ckm4m366scrgk2rm@latitude>
References: <20180220161424.5421-1-j.neuschaefer@gmx.net>
 <20180220161424.5421-2-j.neuschaefer@gmx.net>
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 <20180221135119.d3qgvdck5yruomi7@latitude>
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On Wed, Feb 21, 2018 at 02:51:19PM +0100, Jonathan Neusch=C3=A4fer wrote:
[...]
> While looking through arch/powerpc/mm, I noticed that there's a
> page_is_ram function, which simply uses the memblocks directly, on
> PPC32.

Oops, I misread the code here. memblock is used on PPC64.

> It seems like a good candidate for the RAM check in
> __ioremap_caller, except that there's this code, which apparently
> trashes memblock 0 completely on non-CONFIG_NEED_MULTIPLE_NODES:
>=20
>   https://elixir.bootlin.com/linux/v4.16-rc2/source/arch/powerpc/mm/mem.c=
#L223
>=20
>=20
> Thanks,
> Jonathan Neusch=C3=A4fer


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