| Message ID | 530B4534.3000106@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Feb 24, 2014 at 09:12:20PM +0800, Qin Chuanyu wrote: > with vhost tx zero_copy, guest nic might get hang when host reserving > skb in socket queue delivered by guest, the case has been solved in > tun, it also been needed by bridge. This could easily happened when a > LAST_ACK state tcp occuring between guest and host. > > Signed-off-by: Chuanyu Qin <qinchuanyu@huawei.com> Do you actually observe guest hang? I would expect orphan frags in __netif_receive_skb_core to be enough. > --- > net/bridge/br_input.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c > index 28d5446..744e27a 100644 > --- a/net/bridge/br_input.c > +++ b/net/bridge/br_input.c > @@ -117,6 +117,8 @@ int br_handle_frame_finish(struct sk_buff *skb) > br->dev->stats.multicast++; > } else if ((dst = __br_fdb_get(br, dest, vid)) && > dst->is_local) { > + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) > + goto drop; > skb2 = skb; > /* Do not forward the packet since it's local. */ > skb = NULL; > @@ -136,6 +138,7 @@ int br_handle_frame_finish(struct sk_buff *skb) > out: > return 0; > drop: > + skb_tx_error(skb); > kfree_skb(skb); > goto out; > } > -- > 1.7.3.1.msysgit.0 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2014/2/24 21:29, Michael S. Tsirkin wrote: > On Mon, Feb 24, 2014 at 09:12:20PM +0800, Qin Chuanyu wrote: >> with vhost tx zero_copy, guest nic might get hang when host reserving >> skb in socket queue delivered by guest, the case has been solved in >> tun, it also been needed by bridge. This could easily happened when a >> LAST_ACK state tcp occuring between guest and host. >> >> Signed-off-by: Chuanyu Qin <qinchuanyu@huawei.com> > > Do you actually observe guest hang? > yes, guest nic could not xmit any more until the skb holded by host has been freed, the mainly reason is that though virtio-net could use vring desc out of order, but ubufs is been used by vhost in order. so only one skb could cause guest nic hang. > I would expect orphan frags in > __netif_receive_skb_core to be enough. > yes, it would be better. I would deliver another patch soon. > >> --- >> net/bridge/br_input.c | 3 +++ >> 1 files changed, 3 insertions(+), 0 deletions(-) >> >> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c >> index 28d5446..744e27a 100644 >> --- a/net/bridge/br_input.c >> +++ b/net/bridge/br_input.c >> @@ -117,6 +117,8 @@ int br_handle_frame_finish(struct sk_buff *skb) >> br->dev->stats.multicast++; >> } else if ((dst = __br_fdb_get(br, dest, vid)) && >> dst->is_local) { >> + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) >> + goto drop; >> skb2 = skb; >> /* Do not forward the packet since it's local. */ >> skb = NULL; >> @@ -136,6 +138,7 @@ int br_handle_frame_finish(struct sk_buff *skb) >> out: >> return 0; >> drop: >> + skb_tx_error(skb); >> kfree_skb(skb); >> goto out; >> } >> -- >> 1.7.3.1.msysgit.0 > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2014/2/24 21:52, Qin Chuanyu wrote: > On 2014/2/24 21:29, Michael S. Tsirkin wrote: >> On Mon, Feb 24, 2014 at 09:12:20PM +0800, Qin Chuanyu wrote: >>> with vhost tx zero_copy, guest nic might get hang when host reserving >>> skb in socket queue delivered by guest, the case has been solved in >>> tun, it also been needed by bridge. This could easily happened when a >>> LAST_ACK state tcp occuring between guest and host. >>> >>> Signed-off-by: Chuanyu Qin <qinchuanyu@huawei.com> >> >> Do you actually observe guest hang? >> > yes, guest nic could not xmit any more until the skb holded by host has > been freed, the mainly reason is that though virtio-net could use vring > desc out of order, but ubufs is been used by vhost in order. so only > one skb could cause guest nic hang. >> I would expect orphan frags in >> __netif_receive_skb_core to be enough. >> > yes, it would be better. I would deliver another patch soon. >> After thinking for a while, I think that orphan frags could only been involved in virtual nic receive path, because after __netif_receive_skb_core, skb would been transmitted by physic nic, in this way orphan frags is unnecessary. >>> --- >>> net/bridge/br_input.c | 3 +++ >>> 1 files changed, 3 insertions(+), 0 deletions(-) >>> >>> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c >>> index 28d5446..744e27a 100644 >>> --- a/net/bridge/br_input.c >>> +++ b/net/bridge/br_input.c >>> @@ -117,6 +117,8 @@ int br_handle_frame_finish(struct sk_buff *skb) >>> br->dev->stats.multicast++; >>> } else if ((dst = __br_fdb_get(br, dest, vid)) && >>> dst->is_local) { >>> + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) >>> + goto drop; >>> skb2 = skb; >>> /* Do not forward the packet since it's local. */ >>> skb = NULL; >>> @@ -136,6 +138,7 @@ int br_handle_frame_finish(struct sk_buff *skb) >>> out: >>> return 0; >>> drop: >>> + skb_tx_error(skb); >>> kfree_skb(skb); >>> goto out; >>> } >>> -- >>> 1.7.3.1.msysgit.0 >> >> > > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Feb 24, 2014 at 09:52:11PM +0800, Qin Chuanyu wrote: > On 2014/2/24 21:29, Michael S. Tsirkin wrote: > >On Mon, Feb 24, 2014 at 09:12:20PM +0800, Qin Chuanyu wrote: > >>with vhost tx zero_copy, guest nic might get hang when host reserving > >>skb in socket queue delivered by guest, the case has been solved in > >>tun, it also been needed by bridge. This could easily happened when a > >>LAST_ACK state tcp occuring between guest and host. > >> > >>Signed-off-by: Chuanyu Qin <qinchuanyu@huawei.com> > > > >Do you actually observe guest hang? > > > yes, guest nic could not xmit any more until the skb holded by host has > been freed, the mainly reason is that though virtio-net could use vring > desc out of order, but ubufs is been used by vhost in order. so only > one skb could cause guest nic hang. > >I would expect orphan frags in > >__netif_receive_skb_core to be enough. > > > yes, it would be better. I would deliver another patch soon. well __netif_receive_skb_core already calls orphan frags already. What's left to do? > > > >>--- > >> net/bridge/br_input.c | 3 +++ > >> 1 files changed, 3 insertions(+), 0 deletions(-) > >> > >>diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c > >>index 28d5446..744e27a 100644 > >>--- a/net/bridge/br_input.c > >>+++ b/net/bridge/br_input.c > >>@@ -117,6 +117,8 @@ int br_handle_frame_finish(struct sk_buff *skb) > >> br->dev->stats.multicast++; > >> } else if ((dst = __br_fdb_get(br, dest, vid)) && > >> dst->is_local) { > >>+ if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) > >>+ goto drop; > >> skb2 = skb; > >> /* Do not forward the packet since it's local. */ > >> skb = NULL; > >>@@ -136,6 +138,7 @@ int br_handle_frame_finish(struct sk_buff *skb) > >> out: > >> return 0; > >> drop: > >>+ skb_tx_error(skb); > >> kfree_skb(skb); > >> goto out; > >> } > >>-- > >>1.7.3.1.msysgit.0 > > > > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2014/2/24 23:49, Michael S. Tsirkin wrote: > On Mon, Feb 24, 2014 at 09:52:11PM +0800, Qin Chuanyu wrote: >> On 2014/2/24 21:29, Michael S. Tsirkin wrote: >>> On Mon, Feb 24, 2014 at 09:12:20PM +0800, Qin Chuanyu wrote: >>>> with vhost tx zero_copy, guest nic might get hang when host reserving >>>> skb in socket queue delivered by guest, the case has been solved in >>>> tun, it also been needed by bridge. This could easily happened when a >>>> LAST_ACK state tcp occuring between guest and host. >>>> >>>> Signed-off-by: Chuanyu Qin <qinchuanyu@huawei.com> >>> >>> Do you actually observe guest hang? >>> >> yes, guest nic could not xmit any more until the skb holded by host has >> been freed, the mainly reason is that though virtio-net could use vring >> desc out of order, but ubufs is been used by vhost in order. so only >> one skb could cause guest nic hang. >>> I would expect orphan frags in >>> __netif_receive_skb_core to be enough. >>> >> yes, it would be better. I would deliver another patch soon. > > well __netif_receive_skb_core already calls orphan frags already. > What's left to do? > None :) , I will use with this change. >>> >>>> --- >>>> net/bridge/br_input.c | 3 +++ >>>> 1 files changed, 3 insertions(+), 0 deletions(-) >>>> >>>> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c >>>> index 28d5446..744e27a 100644 >>>> --- a/net/bridge/br_input.c >>>> +++ b/net/bridge/br_input.c >>>> @@ -117,6 +117,8 @@ int br_handle_frame_finish(struct sk_buff *skb) >>>> br->dev->stats.multicast++; >>>> } else if ((dst = __br_fdb_get(br, dest, vid)) && >>>> dst->is_local) { >>>> + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) >>>> + goto drop; >>>> skb2 = skb; >>>> /* Do not forward the packet since it's local. */ >>>> skb = NULL; >>>> @@ -136,6 +138,7 @@ int br_handle_frame_finish(struct sk_buff *skb) >>>> out: >>>> return 0; >>>> drop: >>>> + skb_tx_error(skb); >>>> kfree_skb(skb); >>>> goto out; >>>> } >>>> -- >>>> 1.7.3.1.msysgit.0 >>> >>> >> > > . > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 02/24/2014 09:12 PM, Qin Chuanyu wrote: > with vhost tx zero_copy, guest nic might get hang when host reserving > skb in socket queue delivered by guest, the case has been solved in > tun, it also been needed by bridge. This could easily happened when a > LAST_ACK state tcp occuring between guest and host. > > Signed-off-by: Chuanyu Qin <qinchuanyu@huawei.com> > --- > net/bridge/br_input.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c > index 28d5446..744e27a 100644 > --- a/net/bridge/br_input.c > +++ b/net/bridge/br_input.c > @@ -117,6 +117,8 @@ int br_handle_frame_finish(struct sk_buff *skb) > br->dev->stats.multicast++; > } else if ((dst = __br_fdb_get(br, dest, vid)) && > dst->is_local) { > + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) > + goto drop; > skb2 = skb; > /* Do not forward the packet since it's local. */ > skb = NULL; > @@ -136,6 +138,7 @@ int br_handle_frame_finish(struct sk_buff *skb) > out: > return 0; > drop: > + skb_tx_error(skb); > kfree_skb(skb); > goto out; > } Pretty similar to the issue we found for non-work conserving qdiscs. The questions is whether or not should we audit all such cases ( I believe we could find even more ) and does the skb_orphan_frags(), or doing something like switch to use data copy in this case I will post a patch that switch to use data copy when the number of pending DMAs exceed a limit. Looks like it can help here. Another question is whether or nor do we need a skb_orphan() here now (at least for packets from tun) ? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c index 28d5446..744e27a 100644 --- a/net/bridge/br_input.c +++ b/net/bridge/br_input.c @@ -117,6 +117,8 @@ int br_handle_frame_finish(struct sk_buff *skb) br->dev->stats.multicast++; } else if ((dst = __br_fdb_get(br, dest, vid)) && dst->is_local) { + if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC))) + goto drop; skb2 = skb; /* Do not forward the packet since it's local. */ skb = NULL; @@ -136,6 +138,7 @@ int br_handle_frame_finish(struct sk_buff *skb) out: return 0; drop: + skb_tx_error(skb); kfree_skb(skb); goto out; }
with vhost tx zero_copy, guest nic might get hang when host reserving skb in socket queue delivered by guest, the case has been solved in tun, it also been needed by bridge. This could easily happened when a LAST_ACK state tcp occuring between guest and host. Signed-off-by: Chuanyu Qin <qinchuanyu@huawei.com> --- net/bridge/br_input.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)