Date: Sun, 19 Mar 2017 20:08:21 +0000
From: Mel Gorman <mgorman@techsingularity.net>
To: J?r?me Glisse <jglisse@redhat.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, John Hubbard <jhubbard@nvidia.com>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        David Nellans <dnellans@nvidia.com>,
        Russell King <linux@armlinux.org.uk>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, Chris Metcalf <cmetcalf@mellanox.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [HMM 01/16] mm/memory/hotplug: convert device bool to int to
 allow for more flags v3
Message-ID: <20170319200821.GB2774@techsingularity.net>
References: <1489680335-6594-1-git-send-email-jglisse@redhat.com>
 <1489680335-6594-2-git-send-email-jglisse@redhat.com>
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On Thu, Mar 16, 2017 at 12:05:20PM -0400, J?r?me Glisse wrote:
> When hotpluging memory we want more informations on the type of memory and
> its properties. Replace the device boolean flag by an int and define a set
> of flags.
> 
> New property for device memory is an opt-in flag to allow page migration
> from and to a ZONE_DEVICE. Existing user of ZONE_DEVICE are not expecting
> page migration to work for their pages. New changes to page migration i
> changing that and we now need a flag to explicitly opt-in page migration.
> 
> Changes since v2:
>   - pr_err() in case of hotplug failure
> 
> Changes since v1:
>   - Improved commit message
>   - Improved define name
>   - Improved comments
>   - Typos
> 
> Signed-off-by: J?r?me Glisse <jglisse@redhat.com>

Fairly minor but it's standard for flags to be unsigned due to
uncertainity about what happens when a signed type is bit shifted.
May not apply to your case but fairly trivial to address.