stable.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Jack Wang <xjtuwjp@gmail.com>
To: Dave Jones <davej@codemonkey.org.uk>
Cc: Alexis Bauvin <abauvin@scaleway.com>,
	netdev@vger.kernel.org, stable@vger.kernel.org
Subject: Re: tun: mark small packets as owned by the tap sock
Date: Tue, 13 Aug 2019 09:58:18 +0200	[thread overview]
Message-ID: <CAD+HZHViF0SEbUmRJUoP7tjpYDfU2f8Ev0Gy1Ev9NN8hPV5hyQ@mail.gmail.com> (raw)
In-Reply-To: <20190812221954.GA13314@codemonkey.org.uk>

Dave Jones <davej@codemonkey.org.uk> 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@scaleway.com>
>  > 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@scaleway.com>
>  >     Acked-by: Jason Wang <jasowang@redhat.com>
>
> 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

           reply	other threads:[~2019-08-13  7:58 UTC|newest]

Thread overview: expand[flat|nested]  mbox.gz  Atom feed
 [parent not found: <20190812221954.GA13314@codemonkey.org.uk>]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAD+HZHViF0SEbUmRJUoP7tjpYDfU2f8Ev0Gy1Ev9NN8hPV5hyQ@mail.gmail.com \
    --to=xjtuwjp@gmail.com \
    --cc=abauvin@scaleway.com \
    --cc=davej@codemonkey.org.uk \
    --cc=netdev@vger.kernel.org \
    --cc=stable@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).