[lxc-devel] [PATCH] c/r: use freezer to seize tasks

[Stéphane Graber]

On Fri, Nov 06, 2015 at 05:26:43PM -0700, Tycho Andersen wrote:
> Instead of relying on the old ptrace loop, we should instead put all the
> tasks in the container into the freezer. This will stop them all at the
> same time, preventing fork bombs from causing criu to infinite loop (and is
> also simply a lot faster).
> 
> Note that this uses --freeze-cgroup which isn't in criu 1.7, so it should
> only go into master.
> 
> Signed-off-by: Tycho Andersen <tycho.andersen at canonical.com>

Acked-by: Stéphane Graber <stgraber at ubuntu.com>

> ---
>  src/lxc/criu.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/src/lxc/criu.c b/src/lxc/criu.c
> index 7ee6cbe..695a763 100644
> --- a/src/lxc/criu.c
> +++ b/src/lxc/criu.c
> @@ -37,6 +37,7 @@
>  #include "bdev.h"
>  #include "cgroup.h"
>  #include "conf.h"
> +#include "commands.h"
>  #include "criu.h"
>  #include "log.h"
>  #include "lxc.h"
> @@ -64,8 +65,8 @@ void exec_criu(struct criu_opts *opts)
>  	 * +1 for final NULL */
>  
>  	if (strcmp(opts->action, "dump") == 0) {
> -		/* -t pid */
> -		static_args += 2;
> +		/* -t pid --freeze-cgroup /lxc/ct */
> +		static_args += 4;
>  
>  		/* --leave-running */
>  		if (!opts->stop)
> @@ -133,13 +134,30 @@ void exec_criu(struct criu_opts *opts)
>  		DECLARE_ARG("-vvvvvv");
>  
>  	if (strcmp(opts->action, "dump") == 0) {
> -		char pid[32];
> +		char pid[32], *freezer_relative;
>  
>  		if (sprintf(pid, "%d", opts->c->init_pid(opts->c)) < 0)
>  			goto err;
>  
> +
>  		DECLARE_ARG("-t");
>  		DECLARE_ARG(pid);
> +
> +		freezer_relative = lxc_cmd_get_cgroup_path(opts->c->name,
> +							   opts->c->config_path,
> +							   "freezer");
> +		if (!freezer_relative) {
> +			ERROR("failed getting freezer path");
> +			goto err;
> +		}
> +
> +		ret = snprintf(log, sizeof(log), "/sys/fs/cgroup/freezer/%s", freezer_relative);
> +		if (ret < 0 || ret >= sizeof(log))
> +			goto err;
> +
> +		DECLARE_ARG("--freeze-cgroup");
> +		DECLARE_ARG(log);
> +
>  		if (!opts->stop)
>  			DECLARE_ARG("--leave-running");
>  	} else if (strcmp(opts->action, "restore") == 0) {
> -- 
> 2.6.2
> 
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel

-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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