On Tue, 6 Jan 2026 14:19:23 -0800, Vishwanath Seshagiri <[email protected]> wrote:
> Use page_pool for RX buffer allocation in mergeable and small buffer
> modes. skb_mark_for_recycle() enables page reuse.
>
> Big packets mode is unchanged because it uses page->private for linked
> list chaining of multiple pages per buffer, which conflicts with
> page_pool's internal use of page->private.
>
> Page pools are created in ndo_open and destroyed in remove (not
> ndo_close). This follows existing driver behavior where RX buffers
> remain in the virtqueue across open/close cycles and are only freed
> on device removal.
>
> The rx_mode_work_enabled flag prevents virtnet_rx_mode_work() from
> sending control virtqueue commands while ndo_close is tearing down
> device state. With MEM_TYPE_PAGE_POOL, xdp_rxq_info_unreg() calls
> page_pool_destroy() during close, and concurrent rx_mode_work can
> cause virtqueue corruption. The check is after rtnl_lock() to
> synchronize with ndo_close(), which sets the flag under the same lock.
>
> Signed-off-by: Vishwanath Seshagiri <[email protected]>
> ---
> drivers/net/virtio_net.c | 246 ++++++++++++++++++++++++++++++++-------
> 1 file changed, 205 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 22d894101c01..c36663525c17 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -26,6 +26,7 @@
> #include <net/netdev_rx_queue.h>
> #include <net/netdev_queues.h>
> #include <net/xdp_sock_drv.h>
> +#include <net/page_pool/helpers.h>
>
> static int napi_weight = NAPI_POLL_WEIGHT;
> module_param(napi_weight, int, 0444);
> @@ -359,6 +360,8 @@ struct receive_queue {
> /* Page frag for packet buffer allocation. */
> struct page_frag alloc_frag;
>
> + struct page_pool *page_pool;
> +
> /* RX: fragments + linear part + virtio header */
> struct scatterlist sg[MAX_SKB_FRAGS + 2];
>
> @@ -524,11 +527,13 @@ static int virtnet_xdp_handler(struct bpf_prog
> *xdp_prog, struct xdp_buff *xdp,
> struct virtnet_rq_stats *stats);
> static void virtnet_receive_done(struct virtnet_info *vi, struct
> receive_queue *rq,
> struct sk_buff *skb, u8 flags);
> -static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
> +static struct sk_buff *virtnet_skb_append_frag(struct receive_queue *rq,
> + struct sk_buff *head_skb,
> struct sk_buff *curr_skb,
> struct page *page, void *buf,
> int len, int truesize);
> static void virtnet_xsk_completed(struct send_queue *sq, int num);
> +static void free_unused_bufs(struct virtnet_info *vi);
>
> enum virtnet_xmit_type {
> VIRTNET_XMIT_TYPE_SKB,
> @@ -709,15 +714,24 @@ static struct page *get_a_page(struct receive_queue
> *rq, gfp_t gfp_mask)
> return p;
> }
>
> +static void virtnet_put_page(struct receive_queue *rq, struct page *page,
> + bool allow_direct)
> +{
> + if (rq->page_pool)
> + page_pool_put_page(rq->page_pool, page, -1, allow_direct);
> + else
> + put_page(page);
> +}
> +
> static void virtnet_rq_free_buf(struct virtnet_info *vi,
> struct receive_queue *rq, void *buf)
> {
> if (vi->mergeable_rx_bufs)
> - put_page(virt_to_head_page(buf));
> + virtnet_put_page(rq, virt_to_head_page(buf), false);
> else if (vi->big_packets)
> give_pages(rq, buf);
> else
> - put_page(virt_to_head_page(buf));
> + virtnet_put_page(rq, virt_to_head_page(buf), false);
> }
>
> static void enable_delayed_refill(struct virtnet_info *vi)
> @@ -894,9 +908,11 @@ static struct sk_buff *page_to_skb(struct virtnet_info
> *vi,
> if (unlikely(!skb))
> return NULL;
>
> - page = (struct page *)page->private;
> - if (page)
> - give_pages(rq, page);
> + if (!rq->page_pool) {
> + page = (struct page *)page->private;
> + if (page)
> + give_pages(rq, page);
> + }
> goto ok;
> }
>
> @@ -931,7 +947,10 @@ static struct sk_buff *page_to_skb(struct virtnet_info
> *vi,
> skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, offset,
> frag_size, truesize);
> len -= frag_size;
> - page = (struct page *)page->private;
> + if (!rq->page_pool)
> + page = (struct page *)page->private;
> + else
> + page = NULL;
> offset = 0;
> }
>
> @@ -942,7 +961,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info
> *vi,
> hdr = skb_vnet_common_hdr(skb);
> memcpy(hdr, hdr_p, hdr_len);
> if (page_to_free)
> - put_page(page_to_free);
> + virtnet_put_page(rq, page_to_free, true);
>
> return skb;
> }
> @@ -982,15 +1001,10 @@ static void virtnet_rq_unmap(struct receive_queue *rq,
> void *buf, u32 len)
> static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void
> **ctx)
> {
> struct virtnet_info *vi = rq->vq->vdev->priv;
> - void *buf;
>
> BUG_ON(vi->big_packets && !vi->mergeable_rx_bufs);
>
> - buf = virtqueue_get_buf_ctx(rq->vq, len, ctx);
> - if (buf)
> - virtnet_rq_unmap(rq, buf, *len);
> -
> - return buf;
> + return virtqueue_get_buf_ctx(rq->vq, len, ctx);
> }
>
> static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32
> len)
> @@ -1084,9 +1098,6 @@ static void virtnet_rq_unmap_free_buf(struct virtqueue
> *vq, void *buf)
> return;
> }
>
> - if (!vi->big_packets || vi->mergeable_rx_bufs)
> - virtnet_rq_unmap(rq, buf, 0);
> -
> virtnet_rq_free_buf(vi, rq, buf);
> }
>
> @@ -1352,7 +1363,7 @@ static int xsk_append_merge_buffer(struct virtnet_info
> *vi,
>
> truesize = len;
>
> - curr_skb = virtnet_skb_append_frag(head_skb, curr_skb, page,
> + curr_skb = virtnet_skb_append_frag(rq, head_skb, curr_skb,
> page,
> buf, len, truesize);
> if (!curr_skb) {
> put_page(page);
> @@ -1788,7 +1799,7 @@ static int virtnet_xdp_xmit(struct net_device *dev,
> return ret;
> }
>
> -static void put_xdp_frags(struct xdp_buff *xdp)
> +static void put_xdp_frags(struct xdp_buff *xdp, struct receive_queue *rq)
> {
> struct skb_shared_info *shinfo;
> struct page *xdp_page;
> @@ -1798,7 +1809,7 @@ static void put_xdp_frags(struct xdp_buff *xdp)
> shinfo = xdp_get_shared_info_from_buff(xdp);
> for (i = 0; i < shinfo->nr_frags; i++) {
> xdp_page = skb_frag_page(&shinfo->frags[i]);
> - put_page(xdp_page);
> + virtnet_put_page(rq, xdp_page, true);
> }
> }
> }
> @@ -1914,7 +1925,7 @@ static struct page *xdp_linearize_page(struct
> net_device *dev,
> off = buf - page_address(p);
>
> if (check_mergeable_len(dev, ctx, buflen)) {
> - put_page(p);
> + virtnet_put_page(rq, p, true);
> goto err_buf;
> }
>
> @@ -1922,14 +1933,14 @@ static struct page *xdp_linearize_page(struct
> net_device *dev,
> * is sending packet larger than the MTU.
> */
> if ((page_off + buflen + tailroom) > PAGE_SIZE) {
> - put_page(p);
> + virtnet_put_page(rq, p, true);
> goto err_buf;
> }
>
> memcpy(page_address(page) + page_off,
> page_address(p) + off, buflen);
> page_off += buflen;
> - put_page(p);
> + virtnet_put_page(rq, p, true);
> }
>
> /* Headroom does not contribute to packet length */
> @@ -1979,7 +1990,7 @@ static struct sk_buff *receive_small_xdp(struct
> net_device *dev,
> unsigned int headroom = vi->hdr_len + header_offset;
> struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset;
> struct page *page = virt_to_head_page(buf);
> - struct page *xdp_page;
> + struct page *xdp_page = NULL;
> unsigned int buflen;
> struct xdp_buff xdp;
> struct sk_buff *skb;
> @@ -2013,7 +2024,7 @@ static struct sk_buff *receive_small_xdp(struct
> net_device *dev,
> goto err_xdp;
>
> buf = page_address(xdp_page);
> - put_page(page);
> + virtnet_put_page(rq, page, true);
> page = xdp_page;
> }
>
> @@ -2045,13 +2056,19 @@ static struct sk_buff *receive_small_xdp(struct
> net_device *dev,
> if (metasize)
> skb_metadata_set(skb, metasize);
>
> + if (rq->page_pool && !xdp_page)
> + skb_mark_for_recycle(skb);
> +
> return skb;
>
> err_xdp:
> u64_stats_inc(&stats->xdp_drops);
> err:
> u64_stats_inc(&stats->drops);
> - put_page(page);
> + if (xdp_page)
> + put_page(page);
> + else
> + virtnet_put_page(rq, page, true);
> xdp_xmit:
> return NULL;
> }
> @@ -2099,12 +2116,15 @@ static struct sk_buff *receive_small(struct
> net_device *dev,
> }
>
> skb = receive_small_build_skb(vi, xdp_headroom, buf, len);
> - if (likely(skb))
> + if (likely(skb)) {
> + if (rq->page_pool)
> + skb_mark_for_recycle(skb);
> return skb;
> + }
>
> err:
> u64_stats_inc(&stats->drops);
> - put_page(page);
> + virtnet_put_page(rq, page, true);
> return NULL;
> }
>
> @@ -2159,7 +2179,7 @@ static void mergeable_buf_free(struct receive_queue
> *rq, int num_buf,
> }
> u64_stats_add(&stats->bytes, len);
> page = virt_to_head_page(buf);
> - put_page(page);
> + virtnet_put_page(rq, page, true);
> }
> }
>
> @@ -2270,7 +2290,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device
> *dev,
> offset = buf - page_address(page);
>
> if (check_mergeable_len(dev, ctx, len)) {
> - put_page(page);
> + virtnet_put_page(rq, page, true);
> goto err;
> }
>
> @@ -2289,7 +2309,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device
> *dev,
> return 0;
>
> err:
> - put_xdp_frags(xdp);
> + put_xdp_frags(xdp, rq);
> return -EINVAL;
> }
>
> @@ -2364,7 +2384,7 @@ static void *mergeable_xdp_get_buf(struct virtnet_info
> *vi,
>
> *frame_sz = PAGE_SIZE;
>
> - put_page(*page);
> + virtnet_put_page(rq, *page, true);
>
> *page = xdp_page;
>
> @@ -2386,6 +2406,7 @@ static struct sk_buff *receive_mergeable_xdp(struct
> net_device *dev,
> struct page *page = virt_to_head_page(buf);
> int offset = buf - page_address(page);
> unsigned int xdp_frags_truesz = 0;
> + struct page *org_page = page;
> struct sk_buff *head_skb;
> unsigned int frame_sz;
> struct xdp_buff xdp;
> @@ -2410,6 +2431,8 @@ static struct sk_buff *receive_mergeable_xdp(struct
> net_device *dev,
> head_skb = build_skb_from_xdp_buff(dev, vi, &xdp,
> xdp_frags_truesz);
> if (unlikely(!head_skb))
> break;
> + if (rq->page_pool && page == org_page)
> + skb_mark_for_recycle(head_skb);
> return head_skb;
>
> case XDP_TX:
> @@ -2420,10 +2443,13 @@ static struct sk_buff *receive_mergeable_xdp(struct
> net_device *dev,
> break;
> }
>
> - put_xdp_frags(&xdp);
> + put_xdp_frags(&xdp, rq);
>
> err_xdp:
> - put_page(page);
> + if (page != org_page)
> + put_page(page);
> + else
> + virtnet_put_page(rq, page, true);
> mergeable_buf_free(rq, num_buf, dev, stats);
>
> u64_stats_inc(&stats->xdp_drops);
> @@ -2431,7 +2457,8 @@ static struct sk_buff *receive_mergeable_xdp(struct
> net_device *dev,
> return NULL;
> }
>
> -static struct sk_buff *virtnet_skb_append_frag(struct sk_buff *head_skb,
> +static struct sk_buff *virtnet_skb_append_frag(struct receive_queue *rq,
> + struct sk_buff *head_skb,
> struct sk_buff *curr_skb,
> struct page *page, void *buf,
> int len, int truesize)
> @@ -2463,7 +2490,7 @@ static struct sk_buff *virtnet_skb_append_frag(struct
> sk_buff *head_skb,
>
> offset = buf - page_address(page);
> if (skb_can_coalesce(curr_skb, num_skb_frags, page, offset)) {
> - put_page(page);
> + virtnet_put_page(rq, page, true);
> skb_coalesce_rx_frag(curr_skb, num_skb_frags - 1,
> len, truesize);
> } else {
> @@ -2512,10 +2539,13 @@ static struct sk_buff *receive_mergeable(struct
> net_device *dev,
> }
>
> head_skb = page_to_skb(vi, rq, page, offset, len, truesize, headroom);
> + if (unlikely(!head_skb))
> + goto err_skb;
> +
> curr_skb = head_skb;
>
> - if (unlikely(!curr_skb))
> - goto err_skb;
> + if (rq->page_pool)
> + skb_mark_for_recycle(head_skb);
> while (--num_buf) {
> buf = virtnet_rq_get_buf(rq, &len, &ctx);
> if (unlikely(!buf)) {
> @@ -2534,7 +2564,7 @@ static struct sk_buff *receive_mergeable(struct
> net_device *dev,
> goto err_skb;
>
> truesize = mergeable_ctx_to_truesize(ctx);
> - curr_skb = virtnet_skb_append_frag(head_skb, curr_skb, page,
> + curr_skb = virtnet_skb_append_frag(rq, head_skb, curr_skb,
> page,
> buf, len, truesize);
> if (!curr_skb)
> goto err_skb;
> @@ -2544,7 +2574,7 @@ static struct sk_buff *receive_mergeable(struct
> net_device *dev,
> return head_skb;
>
> err_skb:
> - put_page(page);
> + virtnet_put_page(rq, page, true);
> mergeable_buf_free(rq, num_buf, dev, stats);
>
> err_buf:
> @@ -2683,6 +2713,8 @@ static void receive_buf(struct virtnet_info *vi, struct
> receive_queue *rq,
> static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue
> *rq,
> gfp_t gfp)
> {
> + unsigned int offset;
> + struct page *page;
> char *buf;
> unsigned int xdp_headroom = virtnet_get_headroom(vi);
> void *ctx = (void *)(unsigned long)xdp_headroom;
> @@ -2692,6 +2724,24 @@ static int add_recvbuf_small(struct virtnet_info *vi,
> struct receive_queue *rq,
> len = SKB_DATA_ALIGN(len) +
> SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
>
> + if (rq->page_pool) {
Why we need to check this? The page pool should be created when probing the
device?
> + page = page_pool_alloc_frag(rq->page_pool, &offset, len, gfp);
> + if (unlikely(!page))
> + return -ENOMEM;
> +
> + buf = page_address(page) + offset;
> + buf += VIRTNET_RX_PAD + xdp_headroom;
> +
> + sg_init_table(rq->sg, 1);
> + sg_set_buf(&rq->sg[0], buf, vi->hdr_len + GOOD_PACKET_LEN);
> +
> + err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
> + if (err < 0)
> + page_pool_put_page(rq->page_pool,
> + virt_to_head_page(buf), -1, false);
> + return err;
> + }
> +
> if (unlikely(!skb_page_frag_refill(len, &rq->alloc_frag, gfp)))
> return -ENOMEM;
>
> @@ -2786,6 +2836,8 @@ static int add_recvbuf_mergeable(struct virtnet_info
> *vi,
> unsigned int tailroom = headroom ? sizeof(struct skb_shared_info) : 0;
> unsigned int room = SKB_DATA_ALIGN(headroom + tailroom);
> unsigned int len, hole;
> + unsigned int offset;
> + struct page *page;
> void *ctx;
> char *buf;
> int err;
> @@ -2796,6 +2848,39 @@ static int add_recvbuf_mergeable(struct virtnet_info
> *vi,
> */
> len = get_mergeable_buf_len(rq, &rq->mrg_avg_pkt_len, room);
>
> + if (rq->page_pool) {
> + page = page_pool_alloc_frag(rq->page_pool, &offset,
> + len + room, gfp);
> + if (unlikely(!page))
> + return -ENOMEM;
> +
> + buf = page_address(page) + offset;
> + buf += headroom; /* advance address leaving hole at front of
> pkt */
> +
> + hole = PAGE_SIZE - (offset + len + room);
> + if (hole < len + room) {
> + /* To avoid internal fragmentation, if there is very
> likely not
> + * enough space for another buffer, add the remaining
> space to
> + * the current buffer.
> + * XDP core assumes that frame_size of xdp_buff and the
> length
> + * of the frag are PAGE_SIZE, so we disable the hole
> mechanism.
> + */
> + if (!headroom)
> + len += hole;
> + }
> +
> + ctx = mergeable_len_to_ctx(len + room, headroom);
> +
> + sg_init_table(rq->sg, 1);
> + sg_set_buf(&rq->sg[0], buf, len);
> +
> + err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp);
> + if (err < 0)
> + page_pool_put_page(rq->page_pool,
> + virt_to_head_page(buf), -1, false);
> + return err;
> + }
> +
> if (unlikely(!skb_page_frag_refill(len + room, alloc_frag, gfp)))
> return -ENOMEM;
>
> @@ -3181,7 +3266,10 @@ static int virtnet_enable_queue_pair(struct
> virtnet_info *vi, int qp_index)
> return err;
>
> err = xdp_rxq_info_reg_mem_model(&vi->rq[qp_index].xdp_rxq,
> - MEM_TYPE_PAGE_SHARED, NULL);
> + vi->rq[qp_index].page_pool ?
> + MEM_TYPE_PAGE_POOL :
> + MEM_TYPE_PAGE_SHARED,
> + vi->rq[qp_index].page_pool);
> if (err < 0)
> goto err_xdp_reg_mem_model;
>
> @@ -3221,11 +3309,77 @@ static void virtnet_update_settings(struct
> virtnet_info *vi)
> vi->duplex = duplex;
> }
>
> +static int virtnet_create_page_pools(struct virtnet_info *vi)
> +{
> + int i, err;
> +
> + for (i = 0; i < vi->curr_queue_pairs; i++) {
> + struct receive_queue *rq = &vi->rq[i];
> + struct page_pool_params pp_params = { 0 };
> +
> + if (rq->page_pool)
> + continue;
> +
> + if (rq->xsk_pool)
> + continue;
> +
> + if (!vi->mergeable_rx_bufs && vi->big_packets)
> + continue;
> +
> + pp_params.order = 0;
> + pp_params.pool_size = virtqueue_get_vring_size(rq->vq);
> + pp_params.nid = dev_to_node(vi->vdev->dev.parent);
> + pp_params.dev = vi->vdev->dev.parent;
> + pp_params.netdev = vi->dev;
> + pp_params.napi = &rq->napi;
> + pp_params.flags = 0;
> +
> + rq->page_pool = page_pool_create(&pp_params);
> + if (IS_ERR(rq->page_pool)) {
> + err = PTR_ERR(rq->page_pool);
> + rq->page_pool = NULL;
> + goto err_cleanup;
> + }
> + }
> + return 0;
> +
> +err_cleanup:
> + while (--i >= 0) {
> + struct receive_queue *rq = &vi->rq[i];
> +
> + if (rq->page_pool) {
> + page_pool_destroy(rq->page_pool);
> + rq->page_pool = NULL;
> + }
> + }
> + return err;
> +}
> +
> +static void virtnet_destroy_page_pools(struct virtnet_info *vi)
> +{
> + int i;
> +
> + for (i = 0; i < vi->max_queue_pairs; i++) {
> + struct receive_queue *rq = &vi->rq[i];
> +
> + if (rq->page_pool) {
> + page_pool_destroy(rq->page_pool);
> + rq->page_pool = NULL;
> + }
> + }
> +}
> +
> static int virtnet_open(struct net_device *dev)
> {
> struct virtnet_info *vi = netdev_priv(dev);
> int i, err;
>
> + err = virtnet_create_page_pools(vi);
> + if (err)
> + return err;
> +
> + vi->rx_mode_work_enabled = true;
> +
> enable_delayed_refill(vi);
>
> for (i = 0; i < vi->max_queue_pairs; i++) {
> @@ -3251,6 +3405,7 @@ static int virtnet_open(struct net_device *dev)
> return 0;
>
> err_enable_qp:
> + vi->rx_mode_work_enabled = false;
> disable_delayed_refill(vi);
> cancel_delayed_work_sync(&vi->refill);
>
> @@ -3856,6 +4011,8 @@ static int virtnet_close(struct net_device *dev)
> */
> cancel_work_sync(&vi->config_work);
>
> + vi->rx_mode_work_enabled = false;
> +
> for (i = 0; i < vi->max_queue_pairs; i++) {
> virtnet_disable_queue_pair(vi, i);
> virtnet_cancel_dim(vi, &vi->rq[i].dim);
> @@ -3892,6 +4049,11 @@ static void virtnet_rx_mode_work(struct work_struct
> *work)
>
> rtnl_lock();
>
> + if (!vi->rx_mode_work_enabled) {
> + rtnl_unlock();
> + return;
> + }
> +
> *promisc_allmulti = !!(dev->flags & IFF_PROMISC);
> sg_init_one(sg, promisc_allmulti, sizeof(*promisc_allmulti));
>
> @@ -7193,6 +7355,8 @@ static void remove_vq_common(struct virtnet_info *vi)
>
> free_receive_page_frags(vi);
>
> + virtnet_destroy_page_pools(vi);
> +
> virtnet_del_vqs(vi);
> }
>
> --
> 2.47.3
>
