similar to: [PATCH net] virtio-net: fix page refcnt leaking when fail to allocate frag skb

On Tue, Nov 19, 2013 at 06:03:48AM -0800, Eric Dumazet wrote: > On Tue, 2013-11-19 at 16:05 +0800, Jason Wang wrote: > > We need to drop the refcnt of page when we fail to allocate an skb for frag > > list, otherwise it will be leaked. The bug was introduced by commit > > 2613af0ed18a11d5c566a81f9a6510b73180660a ("virtio_net: migrate mergeable rx > > buffers to page

On Tue, Nov 19, 2013 at 06:03:48AM -0800, Eric Dumazet wrote: > On Tue, 2013-11-19 at 16:05 +0800, Jason Wang wrote: > > We need to drop the refcnt of page when we fail to allocate an skb for frag > > list, otherwise it will be leaked. The bug was introduced by commit > > 2613af0ed18a11d5c566a81f9a6510b73180660a ("virtio_net: migrate mergeable rx > > buffers to page

When mergeable buffer were used, we only put the first page buf leave the rest of buffers in the virt queue. This will cause the driver could not get the correct head buffer any more. Fix this by dropping the rest of buffers for this packet. The bug was introduced by commit 9ab86bbcf8be755256f0a5e994e0b38af6b4d399 (virtio_net: Defer skb allocation in receive path). Cc: Rusty Russell <rusty at

When mergeable buffer were used, we only put the first page buf leave the rest of buffers in the virt queue. This will cause the driver could not get the correct head buffer any more. Fix this by dropping the rest of buffers for this packet. The bug was introduced by commit 9ab86bbcf8be755256f0a5e994e0b38af6b4d399 (virtio_net: Defer skb allocation in receive path). Cc: Rusty Russell <rusty at

On Wed, Nov 20, 2013 at 05:07:26PM +0800, Jason Wang wrote: > We need decrease the rq->num after we can get a buf through > virtqueue_get_buf() even if we could not allocate frag skb. Otherwise, the > refill routine won't be triggered under heavy memory stress since the driver may > still think there's enough room. > > This bug was introduced by commit

On Wed, Nov 20, 2013 at 05:07:26PM +0800, Jason Wang wrote: > We need decrease the rq->num after we can get a buf through > virtqueue_get_buf() even if we could not allocate frag skb. Otherwise, the > refill routine won't be triggered under heavy memory stress since the driver may > still think there's enough room. > > This bug was introduced by commit

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

The virtio_net driver's mergeable receive buffer allocator uses 4KB packet buffers. For MTU-sized traffic, SKB truesize is > 4KB but only ~1500 bytes of the buffer is used to store packet data, reducing the effective TCP window size substantially. This patch addresses the performance concerns with mergeable receive buffers by allocating MTU-sized packet buffers using page frag allocators.

The virtio_net driver's mergeable receive buffer allocator uses 4KB packet buffers. For MTU-sized traffic, SKB truesize is > 4KB but only ~1500 bytes of the buffer is used to store packet data, reducing the effective TCP window size substantially. This patch addresses the performance concerns with mergeable receive buffers by allocating MTU-sized packet buffers using page frag allocators.

On Wed, Nov 20, 2013 at 07:08:50AM -0500, Jason Wang wrote: > > > ----- ???? ----- > > On Wed, Nov 20, 2013 at 05:07:26PM +0800, Jason Wang wrote: > > > We need decrease the rq->num after we can get a buf through > > > virtqueue_get_buf() even if we could not allocate frag skb. Otherwise, the > > > refill routine won't be triggered under heavy

On Wed, Nov 20, 2013 at 07:08:50AM -0500, Jason Wang wrote: > > > ----- ???? ----- > > On Wed, Nov 20, 2013 at 05:07:26PM +0800, Jason Wang wrote: > > > We need decrease the rq->num after we can get a buf through > > > virtqueue_get_buf() even if we could not allocate frag skb. Otherwise, the > > > refill routine won't be triggered under heavy

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

Sometimes we need to coalesce the rx frags to avoid frag list. One example is virtio-net driver which tries to use small frags for both MTU sized packet and GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Michael Dalton <mwdalton at google.com> Cc: Eric Dumazet

On 12/17/2013 08:16 AM, Michael Dalton wrote: > The virtio-net driver currently uses netdev_alloc_frag() for GFP_ATOMIC > mergeable rx buffer allocations. This commit migrates virtio-net to use > per-receive queue page frags for GFP_ATOMIC allocation. This change unifies > mergeable rx buffer memory allocation, which now will use skb_refill_frag() > for both atomic and GFP-WAIT

On 12/17/2013 08:16 AM, Michael Dalton wrote: > The virtio-net driver currently uses netdev_alloc_frag() for GFP_ATOMIC > mergeable rx buffer allocations. This commit migrates virtio-net to use > per-receive queue page frags for GFP_ATOMIC allocation. This change unifies > mergeable rx buffer memory allocation, which now will use skb_refill_frag() > for both atomic and GFP-WAIT

On Tue, Nov 19, 2013 at 01:36:36PM -0800, Eric Dumazet wrote: > On Tue, 2013-11-19 at 22:49 +0200, Michael S. Tsirkin wrote: > > On Tue, Nov 19, 2013 at 06:03:48AM -0800, Eric Dumazet wrote: > > > On Tue, 2013-11-19 at 16:05 +0800, Jason Wang wrote: > > > > We need to drop the refcnt of page when we fail to allocate an skb for frag > > > > list, otherwise

On Tue, Nov 19, 2013 at 01:36:36PM -0800, Eric Dumazet wrote: > On Tue, 2013-11-19 at 22:49 +0200, Michael S. Tsirkin wrote: > > On Tue, Nov 19, 2013 at 06:03:48AM -0800, Eric Dumazet wrote: > > > On Tue, 2013-11-19 at 16:05 +0800, Jason Wang wrote: > > > > We need to drop the refcnt of page when we fail to allocate an skb for frag > > > > list, otherwise