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From:   Jason Andryuk <jandryuk@gmail.com>
Date:   Mon, 7 Dec 2020 15:48:09 -0500
Message-ID: <CAKf6xpuqdY=TctOjNsnTTexeBpkV+HMkOHFsAd4vxUudBpxizA@mail.gmail.com>
Subject: Re: [PATCH 2/2] xen: don't use page->lru for ZONE_DEVICE memory
To:     Juergen Gross <jgross@suse.com>
Cc:     xen-devel <xen-devel@lists.xenproject.org>,
        open list <linux-kernel@vger.kernel.org>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Stefano Stabellini <sstabellini@kernel.org>
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On Mon, Dec 7, 2020 at 8:30 AM Juergen Gross <jgross@suse.com> wrote:
>
> Commit 9e2369c06c8a18 ("xen: add helpers to allocate unpopulated
> memory") introduced usage of ZONE_DEVICE memory for foreign memory
> mappings.
>
> Unfortunately this collides with using page->lru for Xen backend
> private page caches.
>
> Fix that by using page->zone_device_data instead.
>
> Fixes: 9e2369c06c8a18 ("xen: add helpers to allocate unpopulated memory")
> Signed-off-by: Juergen Gross <jgross@suse.com>

Would it make sense to add BUG_ON(is_zone_device_page(page)) and the
opposite as appropriate to cache_enq?  Either way:
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>