linux-kernel - Re: [PATCH v1 2/2] Drivers: virtio: balloon: Report inflated memory

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Date:   Tue, 9 Aug 2022 17:44:49 +0000
From:   Nadav Amit <namit@...are.com>
To:     Alexander Atanasov <alexander.atanasov@...tuozzo.com>
CC:     "Michael S. Tsirkin" <mst@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "kernel@...nvz.org" <kernel@...nvz.org>,
        Wei Liu <wei.liu@...nel.org>,
        Linux Virtualization <virtualization@...ts.linux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Pv-drivers <Pv-drivers@...are.com>
Subject: Re: [PATCH v1 2/2] Drivers: virtio: balloon: Report inflated memory

On Aug 9, 2022, at 2:53 AM, Alexander Atanasov <alexander.atanasov@...tuozzo.com> wrote:

> Update the value in page_alloc on balloon fill/leak.

Some general comments if this patch goes forward.

Please cc pv-drivers@...are.com in the future.

> 
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Wei Liu <wei.liu@...nel.org>
> Cc: Nadav Amit <namit@...are.com>
> 
> Signed-off-by: Alexander Atanasov <alexander.atanasov@...tuozzo.com>
> ---
> drivers/virtio/virtio_balloon.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
> 
> Firts user, other balloons i will do if it is accepted to avoid too much emails.
> 
> 
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index b9737da6c4dd..e2693ffbd48b 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -208,6 +208,16 @@ static void set_page_pfns(struct virtio_balloon *vb,
> 					  page_to_balloon_pfn(page) + i);
> }
> 
> +static void update_meminfo(struct virtio_balloon *vb)

Putting aside the less-than-optimal function name, I would like to ask that
any new generic balloon logic would go into balloon_compaction.[hc] as much
as possible. I made the effort to reuse this infrastructure (which is now
used by both VMware and virtio), and would prefer to share as much code as
possible.

For instance, I would appreciate if the update upon inflate would go into
balloon_page_list_enqueue() and balloon_page_enqueue(). VMware's 2MB pages
logic is not shared, so it would require a change that is specific for
VMware code.