Dave Jones <davej@xxxxxxxxxxxxxxxxx> 于2019年8月13日周二 上午1:05写道： > > On Wed, Aug 07, 2019 at 12:30:07AM +0000, Linux Kernel wrote: > > Commit: 4b663366246be1d1d4b1b8b01245b2e88ad9e706 > > Parent: 16b2084a8afa1432d14ba72b7c97d7908e178178 > > Web: https://git.kernel.org/torvalds/c/4b663366246be1d1d4b1b8b01245b2e88ad9e706 > > Author: Alexis Bauvin <abauvin@xxxxxxxxxxxx> > > AuthorDate: Tue Jul 23 16:23:01 2019 +0200 > > > > tun: mark small packets as owned by the tap sock > > > > - v1 -> v2: Move skb_set_owner_w to __tun_build_skb to reduce patch size > > > > Small packets going out of a tap device go through an optimized code > > path that uses build_skb() rather than sock_alloc_send_pskb(). The > > latter calls skb_set_owner_w(), but the small packet code path does not. > > > > The net effect is that small packets are not owned by the userland > > application's socket (e.g. QEMU), while large packets are. > > This can be seen with a TCP session, where packets are not owned when > > the window size is small enough (around PAGE_SIZE), while they are once > > the window grows (note that this requires the host to support virtio > > tso for the guest to offload segmentation). > > All this leads to inconsistent behaviour in the kernel, especially on > > netfilter modules that uses sk->socket (e.g. xt_owner). > > > > Fixes: 66ccbc9c87c2 ("tap: use build_skb() for small packet") > > Signed-off-by: Alexis Bauvin <abauvin@xxxxxxxxxxxx> > > Acked-by: Jason Wang <jasowang@xxxxxxxxxx> > > This commit breaks ipv6 routing when I deployed on it a linode. > It seems to work briefly after boot, and then silently all packets get > dropped. (Presumably, it's dropping RA or ND packets) > > With this reverted, everything works as it did in rc3. > > Dave > Thanks for reporting, Dave. +cc stable Just noticed, the patch has been backported to 4.14,4.19, 5.2 Regards, Jack Wang
