[CRIU] Error (sk-inet.c:153): In-flight connection (l) for 4bad5

[Adrian Reber]

On Mon, Jun 06, 2016 at 02:56:22PM +0300, Pavel Emelyanov wrote:
> On 06/01/2016 07:19 PM, Adrian Reber wrote:
> > On Wed, Jun 01, 2016 at 11:56:02AM +0300, Pavel Emelyanov wrote:
> >> On 05/31/2016 06:27 PM, Adrian Reber wrote:
> >>> I have a lxc container with a tomcat server and postgresql database in
> >>> it. The tomcat server is running an test application which connects to
> >>> the database, reads and modifies a field.
> >>>
> >>> I can checkpoint and restart that container most of the times. If I am
> >>> reloading the tomcat application in a while true; do loop with curl I
> >>> sometimes get a dump failure like this:
> >>>
> >>> 27112 fdinfo 50: pos: 0x               0 flags:             4002/0
> >>> 	Searching for socket 4bad5 (family 10.6)
> >>> Error (sk-inet.c:153): In-flight connection (l) for 4bad5
> >>> ----------------------------------------
> >>> Error (cr-dump.c:1312): Dump files (pid: 27112) failed with -1
> >>>
> >>> I guess this is a TCP connection which is in a state that criu cannot
> >>> handle. Is that correct?
> >>
> >> Yes. This happens when a client sens SYN to server, server responds with
> >> SYN-ACK, but the almost-new connection hasn't yet been accept()-ed by
> >> server.
> > 
> > Thanks for the explanation. Is there any way to checkpoint a container
> > with such connection?
> 
> Only unseizing/unfreezing it and waiting for the connection to get accepted.
> 
> > Would it be possible to drop a TCP connection in
> > that state. I would rather see my container migrated than an error
> > during checkpointing. It would be 'unfortunate' for the client as the
> > connection establishment fails and is silently dropped, but I guess
> > the TCP stack will resend the packages after a timeout.
> 
> Yes, we can patch criu to just ignore this thing. The conn request will end
> up with reset flag send to peer and the container being migrated won't
> even notice it.

Okay, let me provide a patch that provides a new option telling criu to
ignore connections in this state.

		Adrian