OpenVZ creates per-container kernel threads and they live in
container's cgroups. CRIU should skip these threads, it's impossiable to
get any state of them.
Signed-off-by: Andrew Vagin <avagin@virtuozzo.org>
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Without using a freezer cgroup, we need to do a few iterations to catch
all tasks, because a new tasks can be born. If new tasks appear faster
than criu collects them, criu fails. The freezer cgroup allows to
solve this problem.
We freeze the freezer group, then attaches to tasks with ptrace and thaw
the freezer cgroup. We suppose that all tasks which are going to be
dumped in a specified freezer group.
v2: fix comments from Christopher
Reviewed-by: Christopher Covington <cov@codeaurora.org>
v3: refactor task_seize
v4: fix comments from Pavel
Cc: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Before cr_errno was called from open_pid_proc(), but
now it isn't called if a root task doesn't exist.
Reported-by: Mr Jenkins
Fixes: b9b0730cb1 ("ptrace: split task_seize into seize_catch_task and seize_wait_task")
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
It's preparation to use a freezer cgroup for freezing tasks.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
