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

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Date: Wed, 3 Jan 2024 17:18:31 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Jason Wang <jasowang@...hat.com>,
	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 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>