Re: [PATCH net 3/9] virtio-net: fix page miscount during XDP linearizing

2016-12-25 Thread Jason Wang 



On 2016年12月23日 23:54, John Fastabend wrote:

On 16-12-23 06:37 AM, Jason Wang wrote:

We don't put page during linearizing, the would cause leaking when
xmit through XDP_TX or the packet exceeds PAGE_SIZE. Fix them by
put page accordingly. Also decrease the number of buffers during
linearizing to make sure caller can free buffers correctly when packet
exceeds PAGE_SIZE. With this patch, we won't get OOM after linearize
huge number of packets.

Cc: John Fastabend 
Signed-off-by: Jason Wang 
---

Thanks! looks good. By the way do you happen to have any actual
configuration where this path is hit? I obviously didn't test this
very long other than a quick test with my hacked vhost driver.

Acked-by: John Fastabend 


Yes, I have. Just increase the MTU above 1500 for both virtio and tap 
and produce some traffic with size which will lead underestimated of rxbuf.


Thanks

Re: [PATCH net 3/9] virtio-net: fix page miscount during XDP linearizing

2016-12-23 Thread John Fastabend 
On 16-12-23 06:37 AM, Jason Wang wrote:
> We don't put page during linearizing, the would cause leaking when
> xmit through XDP_TX or the packet exceeds PAGE_SIZE. Fix them by
> put page accordingly. Also decrease the number of buffers during
> linearizing to make sure caller can free buffers correctly when packet
> exceeds PAGE_SIZE. With this patch, we won't get OOM after linearize
> huge number of packets.
> 
> Cc: John Fastabend 
> Signed-off-by: Jason Wang 
> ---

Thanks! looks good. By the way do you happen to have any actual
configuration where this path is hit? I obviously didn't test this
very long other than a quick test with my hacked vhost driver.

Acked-by: John Fastabend

[PATCH net 3/9] virtio-net: fix page miscount during XDP linearizing

2016-12-23 Thread Jason Wang 
We don't put page during linearizing, the would cause leaking when
xmit through XDP_TX or the packet exceeds PAGE_SIZE. Fix them by
put page accordingly. Also decrease the number of buffers during
linearizing to make sure caller can free buffers correctly when packet
exceeds PAGE_SIZE. With this patch, we won't get OOM after linearize
huge number of packets.

Cc: John Fastabend 
Signed-off-by: Jason Wang 
---
 drivers/net/virtio_net.c | 19 +++
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index fe4562d..58ad40e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -483,7 +483,7 @@ static struct sk_buff *receive_big(struct net_device *dev,
  * anymore.
  */
 static struct page *xdp_linearize_page(struct receive_queue *rq,
-  u16 num_buf,
+  u16 *num_buf,
   struct page *p,
   int offset,
   unsigned int *len)
@@ -497,7 +497,7 @@ static struct page *xdp_linearize_page(struct receive_queue 
*rq,
memcpy(page_address(page) + page_off, page_address(p) + offset, *len);
page_off += *len;
 
-   while (--num_buf) {
+   while (--*num_buf) {
unsigned int buflen;
unsigned long ctx;
void *buf;
@@ -507,19 +507,22 @@ static struct page *xdp_linearize_page(struct 
receive_queue *rq,
if (unlikely(!ctx))
goto err_buf;
 
+   buf = mergeable_ctx_to_buf_address(ctx);
+   p = virt_to_head_page(buf);
+   off = buf - page_address(p);
+
/* guard against a misconfigured or uncooperative backend that
 * is sending packet larger than the MTU.
 */
-   if ((page_off + buflen) > PAGE_SIZE)
+   if ((page_off + buflen) > PAGE_SIZE) {
+   put_page(p);
goto err_buf;
-
-   buf = mergeable_ctx_to_buf_address(ctx);
-   p = virt_to_head_page(buf);
-   off = buf - page_address(p);
+   }
 
memcpy(page_address(page) + page_off,
   page_address(p) + off, buflen);
page_off += buflen;
+   put_page(p);
}
 
*len = page_off;
@@ -555,7 +558,7 @@ static struct sk_buff *receive_mergeable(struct net_device 
*dev,
/* This happens when rx buffer size is underestimated */
if (unlikely(num_buf > 1)) {
/* linearize data for XDP */
-   xdp_page = xdp_linearize_page(rq, num_buf,
+   xdp_page = xdp_linearize_page(rq, &num_buf,
  page, offset, &len);
if (!xdp_page)
goto err_xdp;
-- 
2.7.4