Some controllers can be disabled in kernel options. In this case they
are shown in /proc/cgroups, but they could not be mounted.
All enabled controllers can be collected from /proc/self/cgroup.
https://github.com/xemul/criu/issues/28
v2: ',' is used to separate controllers
Cc: Tycho Andersen <tycho.andersen@canonical.com>
Reported-by: Ross Boucher <boucher@gmail.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
The motivation for this is to be able to restore containers into cgroups other
than what they were dumped in (if, e.g. they might conflict with an existing
container). Suppose you have a container in:
memory:/mycontainer
cpuacct,cpu:/mycontainer
blkio:/mycontainer
name=systemd:/mycontainer
You could then restore them to /mycontainer2 via --cgroup-root /mycontainer2.
If you want to restore different controllers to different paths, you can
provide multiple arguments, for example, passing:
--cgroup-root /mycontainer2 --cgroup-root cpuacct,cpu:/specialcpu \
--cgroup-root name=systemd:/specialsystemd
Would result in things being restored to:
memory:/mycontainer2
cpuacct,cpu:/specialcpu
blkio:/mycontainer2
name=systemd:/specialsystemd
i.e. a --cgroup-root without a controller prefix specifies the new default root
for all cgroups.
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Restores 2 cgroup properties after the criu restoration of tasks.
Currently the cgroup files to be restored are static but
are easily extendable. To change the properties to be restored,
edit this list at the top of cgroup.c. If a cgroup exists during
restoration, its properties will not be overwritten.
Work based off Tycho Anderson tycho.andersen@canonical.com
Change-Id: Ida32b9773eeac1d4d6e82ad644524ed099d5f9b1
Signed-off-by: Garrison Bellack <gbellack@google.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
During the dump phase, /proc/cgroups is parsed to find co-mounted cgroups.
Then, for each task /proc/self/cgroup is parsed for the cgroups that it is a
member of, and that cgroup is traversed to find any child cgroups which may
also need restoring. Any cgroups not currently mounted will be temporarily
mounted and traversed. All of this information is persisted along with the
original cg_sets, which indicate which cgroups a task is a member of.
On restore, an initial phase creates all the cgroups which were saved. Tasks
are then restored into these cgroups via cg_sets as usual.
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
On restore find out in which sets tasks live in and move
them there.
Optimization note -- move tasks into cgroups _before_ fork
kids to make them inherit cgroups if required. This saves
a lot of time.
Accessibility note -- when moving tasks into cgroups don't
search for existing host mounts (they may be not available)
and don't mount temporary ones (may be impossible due to
user namespaces). Instead introduce service fd with a yard
of mounts.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Each task points to a single ID of cgroup-set it lives in. This
is done so to save some space in the image, as tasks likely
live in the same set of cgroups.
Other than this we keep track of what cgroup set we dump the
subtree from. If it happens, that root task lives in the same
cgroup set as criu does, we don't allow for any other sub-cgroups
and make restore (next patch) much simpler and faster.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
