> +               goto fail_hdr_dmamap_destroy;
> +
> +       error =3D sglist_append_phys(sg, hdr_paddr, sc->vtnet_hdr_size);
>         if (error !=3D 0 || sg->sg_nseg !=3D 1) {
>                 KASSERT(0, ("%s: cannot add header to sglist error %d nse=
g %d",
>                     __func__, error, sg->sg_nseg));
> -               goto fail;
> +               goto fail_hdr_dmamap_unload;
>         }
>
> -       error =3D sglist_append_mbuf(sg, m);
> +       bus_dmamap_sync(sc->vtnet_tx_dmat, hdr_dmap, BUS_DMASYNC_PREWRITE=
);
> +
> +       error =3D bus_dmamap_create(sc->vtnet_tx_dmat, 0, &dmap);
> +       if (error)
> +               goto fail_hdr_dmamap_unload;
> +
> +       nsegs =3D 0;
> +       error =3D bus_dmamap_load_mbuf_sg(sc->vtnet_tx_dmat, dmap, m, seg=
s,
> +           &nsegs, BUS_DMA_NOWAIT);
> +       if (error !=3D 0)
> +               goto fail_dmamap_destroy;
> +       KASSERT(nsegs <=3D sc->vtnet_tx_nsegs,
> +           ("%s: unexpected number of DMA segments for tx buffer: %d (ma=
x %d)",
> +           __func__, nsegs, sc->vtnet_tx_nsegs));
> +
> +       bus_dmamap_sync(sc->vtnet_tx_dmat, dmap, BUS_DMASYNC_PREWRITE);
> +
> +       for (i =3D 0; i < nsegs && !error; i++)
> +               error =3D sglist_append_phys(sg, segs[i].ds_addr, segs[i]=
.ds_len);
> +
>         if (error) {
> +               sglist_reset(sg);
> +               bus_dmamap_unload(sc->vtnet_tx_dmat, dmap);
> +
> +               error =3D sglist_append_phys(sg, hdr_paddr, sc->vtnet_hdr=
_size);
> +               if (error !=3D 0 || sg->sg_nseg !=3D 1) {
> +                       KASSERT(0, ("%s: cannot add header to sglist erro=
r %d nseg %d",
> +                           __func__, error, sg->sg_nseg));
> +                       goto fail_dmamap_destroy;
> +               }
> +
>                 m =3D m_defrag(m, M_NOWAIT);
>                 if (m =3D=3D NULL) {
>                         sc->vtnet_stats.tx_defrag_failed++;
> @@ -2545,16 +2761,41 @@ vtnet_txq_enqueue_buf(struct vtnet_txq *txq, stru=
ct mbuf **m_head,
>                 *m_head =3D m;
>                 sc->vtnet_stats.tx_defragged++;
>
> -               error =3D sglist_append_mbuf(sg, m);
> +               nsegs =3D 0;
> +               error =3D bus_dmamap_load_mbuf_sg(sc->vtnet_tx_dmat, dmap=
, m,
> +                   segs, &nsegs, BUS_DMA_NOWAIT);
> +               if (error !=3D 0)
> +                       goto fail_dmamap_destroy;
> +               KASSERT(nsegs <=3D sc->vtnet_tx_nsegs,
> +                   ("%s: unexpected number of DMA segments for tx buffer=
: %d (max %d)",
> +                   __func__, nsegs, sc->vtnet_tx_nsegs));
> +
> +               bus_dmamap_sync(sc->vtnet_tx_dmat, dmap, BUS_DMASYNC_PREW=
RITE);
> +
> +               for (i =3D 0; i < nsegs && !error; i++)
> +                       error =3D sglist_append_phys(sg, segs[i].ds_addr,
> +                           segs[i].ds_len);
> +
>                 if (error)
> -                       goto fail;
> +                       goto fail_dmamap_unload;
>         }
>
>         txhdr->vth_mbuf =3D m;
> +       txhdr->dmap =3D dmap;
> +       txhdr->hdr_dmap =3D hdr_dmap;
> +
>         error =3D virtqueue_enqueue(vq, txhdr, sg, sg->sg_nseg, 0);
>
>         return (error);
>
> +fail_dmamap_unload:
> +       bus_dmamap_unload(sc->vtnet_tx_dmat, dmap);
> +fail_dmamap_destroy:
> +       bus_dmamap_destroy(sc->vtnet_tx_dmat, dmap);
> +fail_hdr_dmamap_unload:
> +       bus_dmamap_unload(sc->vtnet_tx_dmat, hdr_dmap);
> +fail_hdr_dmamap_destroy:
> +       bus_dmamap_destroy(sc->vtnet_tx_dmat, hdr_dmap);
>  fail:
>         m_freem(*m_head);
>         *m_head =3D NULL;
> diff --git a/sys/dev/virtio/network/if_vtnetvar.h b/sys/dev/virtio/networ=
k/if_vtnetvar.h
> index eb5e6784b07f..6cafe827d733 100644
> --- a/sys/dev/virtio/network/if_vtnetvar.h
> +++ b/sys/dev/virtio/network/if_vtnetvar.h
> @@ -190,6 +190,12 @@ struct vtnet_softc {
>         struct mtx               vtnet_mtx;
>         char                     vtnet_mtx_name[16];
>         uint8_t                  vtnet_hwaddr[ETHER_ADDR_LEN];
> +
> +       bus_dma_tag_t            vtnet_rx_dmat;
> +       struct mtx               vtnet_rx_mtx;
> +
> +       bus_dma_tag_t            vtnet_tx_dmat;
> +       struct mtx               vtnet_tx_mtx;
>  };
>  /* vtnet flag descriptions for use with printf(9) %b identifier. */
>  #define VTNET_FLAGS_BITS \
> @@ -273,6 +279,10 @@ struct vtnet_tx_header {
>         } vth_uhdr;
>
>         struct mbuf *vth_mbuf;
> +
> +       bus_dmamap_t dmap;
> +
> +       bus_dmamap_t hdr_dmap;
>  };
>
>  /*
>

I believe this is causing a massive memory leak in the devbuf malloc
type.  I can't even get through a build over nfs on a VM without
hitting OOM.  Reverting b5bad6df467cc95bea641afe674c55cd5b9f1510 and
c16c95192f01237a876eb7bc336e3bbda9310171 fixes the leak.  Can you
please fix or revert this?

You can monitor the leak with something like
vmstat -m | grep devbuf

> @@ -1562,13 +1643,43 @@ vtnet_rx_alloc_buf(struct vtnet_softc *sc, int nb=
ufs, struct mbuf **m_tailp)
>                 }
>
>                 m->m_len =3D size;
> +               vthdr =3D (struct vtnet_rx_buffer_header *)m->m_data;
> +
> +               /* Reserve space for header */
> +               m_adj(m, VTNET_RX_BUFFER_HEADER_OFFSET);
> +
>                 /*
>                  * Need to offset the mbuf if the header we're going to a=
dd
>                  * will misalign.
>                  */
> -               if (VTNET_ETHER_ALIGN !=3D 0 && sc->vtnet_hdr_size % 4 =
=3D=3D 0) {
> +               if (VTNET_ETHER_ALIGN !=3D 0 && sc->vtnet_hdr_size % 4 =
=3D=3D 0)
>                         m_adj(m, VTNET_ETHER_ALIGN);
> +
> +               err =3D bus_dmamap_create(sc->vtnet_rx_dmat, 0, &dmap);
> +               if (err) {
> +                       printf("Failed to create dmamap, err :%d\n",
> +                           err);
> +                       m_freem(m);
> +                       return (NULL);
>                 }
> +
> +               nsegs =3D 0;
> +               err =3D bus_dmamap_load_mbuf_sg(sc->vtnet_rx_dmat, dmap, =
m, segs,
> +                   &nsegs, BUS_DMA_NOWAIT);

Where is the bus_dmamap_unload and bus_dmamap_destroy for the rx bufs?

Ryan