[CRIU] [PATCH] dump: pre-load kernel modules

[Tycho Andersen]

On Thu, Dec 11, 2014 at 04:55:34PM -0500, Christopher Covington wrote:
> On 10/14/2014 06:21 AM, Pavel Emelyanov wrote:
> > On 10/14/2014 11:49 AM, Tycho Andersen wrote:
> 
> >> diff --git a/sockets.c b/sockets.c
> >> index 0268d35..6c71503 100644
> >> --- a/sockets.c
> >> +++ b/sockets.c
> >> @@ -96,6 +96,41 @@ bool socket_test_collect_bit(unsigned int family, unsigned int proto)
> >>  	return test_bit(nr, socket_cl_bits) != 0;
> >>  }
> >>  
> >> +void preload_socket_modules()
> >> +{
> >> +	/*
> >> +	 * If the task to dump (e.g. an LXC container) has any netlink
> >> +	 * KOBJECT_UEVENT socket open and the _diag modules aren't
> >> +	 * loaded is dumped, criu will freeze the task and then the
> >> +	 * kernel will send it messages on the socket, and then we will
> >> +	 * fail to dump because the socket has pending data. The Real
> >> +	 * Solution is to dump this pending data, but we just modprobe
> >> +	 * things beforehand for now so that the first dump doesn't
> >> +	 * fail.
> >> +	 *
> >> +	 * We ignore failure since these could be compiled directly
> >> +	 * in, instead of being kernel modules.
> >> +	 */
> >> +	char *modules[] = {
> >> +		"netlink_diag",
> >> +		"af_packet_diag",
> >> +		"udp_diag",
> >> +		"tcp_diag",
> >> +		"unix_diag",
> >> +		NULL,
> >> +	};
> >> +	int i;
> >> +	char *args[2] = {
> >> +		"modprobe",
> >> +		NULL
> >> +	};
> >> +
> >> +	for (i = 0; modules[i]; i++) {
> >> +		args[1] = modules[i];
> >> +		cr_system(-1, -1, -1, args[0], args);
> 
> With this patch I get the following spurious prints. Is there some way they
> could be avoided?

I suppose they could be avoided by checking if the modules are already
loaded, but modprobe shouldn't exit 1 in that case. Do you know why it
is failing?

Tycho

> (00.058688) Error (util.c:571): exited, status=1
> (00.112076) Error (util.c:571): exited, status=1
> (00.161681) Error (util.c:571): exited, status=1
> (00.200197) Error (util.c:571): exited, status=1
> (00.251205) Error (util.c:571): exited, status=1
> 
> >> +	}
> >> +}
> 
> Thanks,
> Chris
> 
> -- 
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