netdev - Re: [PATCH v2] virtio_net: fix missing dma unmap for resize

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Date: Thu, 4 Jan 2024 10:35:51 +0800
From: Jason Wang <jasowang@...hat.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Jakub Kicinski <kuba@...nel.org>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, 
	virtualization@...ts.linux-foundation.org, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v2] virtio_net: fix missing dma unmap for resize

On Thu, Jan 4, 2024 at 6:18 AM Michael S. Tsirkin <mst@...hat.com> wrote:
>
> On Wed, Jan 03, 2024 at 01:58:03PM -0800, Jakub Kicinski wrote:
> > On Tue, 26 Dec 2023 17:43:33 +0800 Xuan Zhuo wrote:
> > > For rq, we have three cases getting buffers from virtio core:
> > >
> > > 1. virtqueue_get_buf{,_ctx}
> > > 2. virtqueue_detach_unused_buf
> > > 3. callback for virtqueue_resize
> > >
> > > But in commit 295525e29a5b("virtio_net: merge dma operations when
> > > filling mergeable buffers"), I missed the dma unmap for the #3 case.
> > >
> > > That will leak some memory, because I did not release the pages referred
> > > by the unused buffers.
> > >
> > > If we do such script, we will make the system OOM.
> > >
> > >     while true
> > >     do
> > >             ethtool -G ens4 rx 128
> > >             ethtool -G ens4 rx 256
> > >             free -m
> > >     done
> > >
> > > Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers")
> > > Signed-off-by: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
> >
> > Michael, Jason, looks good? Worth pushing it to v6.7?
>
> I'd say yes.
>
> Acked-by: Michael S. Tsirkin <mst@...hat.com>

Acked-by: Jason Wang <jasowang@...hat.com>

Thanks

>