linux-kernel - Re: [PATCH v1 12/29] virtio-mem: factor out fake-offlining into virtio_mem_fake

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Date:   Tue, 20 Oct 2020 11:31:22 +0200
From:   Pankaj Gupta <pankaj.gupta.linux@...il.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>,
        virtualization@...ts.linux-foundation.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>
Subject: Re: [PATCH v1 12/29] virtio-mem: factor out fake-offlining into virtio_mem_fake_offline()

> ... which now matches virtio_mem_fake_online(). We'll reuse this
> functionality soon.
>
> Cc: "Michael S. Tsirkin" <mst@...hat.com>
> Cc: Jason Wang <jasowang@...hat.com>
> Cc: Pankaj Gupta <pankaj.gupta.linux@...il.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---
>  drivers/virtio/virtio_mem.c | 34 ++++++++++++++++++++++++----------
>  1 file changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
> index 00d1cfca4713..d132bc54ef57 100644
> --- a/drivers/virtio/virtio_mem.c
> +++ b/drivers/virtio/virtio_mem.c
> @@ -832,6 +832,27 @@ static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
>         }
>  }
>
> +/*
> + * Try to allocate a range, marking pages fake-offline, effectively
> + * fake-offlining them.
> + */
> +static int virtio_mem_fake_offline(unsigned long pfn, unsigned long nr_pages)
> +{
> +       int rc;
> +
> +       rc = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE,
> +                               GFP_KERNEL);
> +       if (rc == -ENOMEM)
> +               /* whoops, out of memory */
> +               return rc;
> +       if (rc)
> +               return -EBUSY;
> +
> +       virtio_mem_set_fake_offline(pfn, nr_pages, true);
> +       adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
> +       return 0;
> +}
> +
>  static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
>  {
>         const unsigned long addr = page_to_phys(page);
> @@ -1335,17 +1356,10 @@ static int virtio_mem_mb_unplug_sb_online(struct virtio_mem *vm,
>
>         start_pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
>                              sb_id * vm->subblock_size);
> -       rc = alloc_contig_range(start_pfn, start_pfn + nr_pages,
> -                               MIGRATE_MOVABLE, GFP_KERNEL);
> -       if (rc == -ENOMEM)
> -               /* whoops, out of memory */
> -               return rc;
> -       if (rc)
> -               return -EBUSY;
>
> -       /* Mark it as fake-offline before unplugging it */
> -       virtio_mem_set_fake_offline(start_pfn, nr_pages, true);
> -       adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
> +       rc = virtio_mem_fake_offline(start_pfn, nr_pages);
> +       if (rc)
> +               return rc;
>
>         /* Try to unplug the allocated memory */
>         rc = virtio_mem_mb_unplug_sb(vm, mb_id, sb_id, count);

Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@...il.com>