在 2021/6/4 上午1:09, Xuan Zhuo 写道:
In virtio-net's large packet mode, there is a hole in the space behind
buf.
before the buf actually or behind the vnet header?
hdr_padded_len - hdr_len
We must take this into account when calculating tailroom.
[ 44.544385] skb_put.cold (net/core/skbuff.c:5254 (discriminator 1) net/core/skbuff.c:5252 (discriminator 1))
[ 44.544864] page_to_skb (drivers/net/virtio_net.c:485) [ 44.545361] receive_buf (drivers/net/virtio_net.c:849 drivers/net/virtio_net.c:1131)
[ 44.545870] ? netif_receive_skb_list_internal (net/core/dev.c:5714)
[ 44.546628] ? dev_gro_receive (net/core/dev.c:6103)
[ 44.547135] ? napi_complete_done (./include/linux/list.h:35 net/core/dev.c:5867 net/core/dev.c:5862 net/core/dev.c:6565)
[ 44.547672] virtnet_poll (drivers/net/virtio_net.c:1427 drivers/net/virtio_net.c:1525)
[ 44.548251] __napi_poll (net/core/dev.c:6985)
[ 44.548744] net_rx_action (net/core/dev.c:7054 net/core/dev.c:7139)
[ 44.549264] __do_softirq (./arch/x86/include/asm/jump_label.h:19 ./include/linux/jump_label.h:200 ./include/trace/events/irq.h:142 kernel/softirq.c:560)
[ 44.549762] irq_exit_rcu (kernel/softirq.c:433 kernel/softirq.c:637 kernel/softirq.c:649)
[ 44.551384] common_interrupt (arch/x86/kernel/irq.c:240 (discriminator 13))
[ 44.551991] ? asm_common_interrupt (./arch/x86/include/asm/idtentry.h:638)
[ 44.552654] asm_common_interrupt (./arch/x86/include/asm/idtentry.h:638)
Fixes: fb32856b16ad ("virtio-net: page_to_skb() use build_skb when there's sufficient tailroom")
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Reported-by: Corentin Noël <corentin.noel@xxxxxxxxxxxxx>
Tested-by: Corentin Noël <corentin.noel@xxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index fa407eb8b457..78a01c71a17c 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -406,7 +406,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
* add_recvbuf_mergeable() + get_mergeable_buf_len()
*/
truesize = headroom ? PAGE_SIZE : truesize;
- tailroom = truesize - len - headroom;
+ tailroom = truesize - len - headroom - (hdr_padded_len - hdr_len);
The patch looks correct and I saw it has been merged.
But I prefer to do that in receive_big() instead of here.
Thanks
buf = p - headroom;
len -= hdr_len;
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