Re: [PATCH v2 1/2] vhost: fix memory leak in Virtio Tx split path

[David Marchand <david.marchand@redhat.com>]

On Wed, Jan 31, 2024 at 8:53 PM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
>
> When vIOMMU is enabled and Virtio device is bound to kernel
> driver in guest, rte_vhost_dequeue_burst() will often return
> early because of IOTLB misses.

In theory, we can hit this issue with a dpdk pmd too, as long as the
vIOMMU is in use.
But the consequence would be a "really small" leak which does not have
the same impact as what was seen with the kernel driver which
maps/unmaps pages associated with virtio-net skb way more often :-).
So maybe rephrase this part emphasizing on the kernel case like:

"""
When vIOMMU is enabled, rte_vhost_dequeue_burst() can return early
because of IOTLB misses.
Such IOTLB misses are especially frequent when a Virtio device is
bound to a kernel driver in guest.
"""

>
> This patch fixes a mbuf leak occurring in this case.
>
> Fixes: 242695f6122a ("vhost: allocate and free packets in bulk in Tx split")
> Cc: stable@dpdk.org
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> Signed-off-by: David Marchand <david.marchand@redhat.com>

Reviewed-by: David Marchand <david.marchand@redhat.com>


-- 
David Marchand