On Fri, Nov 30, 2018 at 03:47:45PM -0800, Roman Gushchin wrote: > Describe cgroup v2 freezer interface in the cgroup v2 admin guide. > > Signed-off-by: Roman Gushchin <guro@xxxxxx> > Cc: Tejun Heo <tj@xxxxxxxxxx> > Cc: linux-doc@xxxxxxxxxxxxxxx > Cc: kernel-team@xxxxxx Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > --- > Documentation/admin-guide/cgroup-v2.rst | 27 +++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index 07e06136a550..f8335e26b362 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -864,6 +864,8 @@ All cgroup core files are prefixed with "cgroup." > populated > 1 if the cgroup or its descendants contains any live > processes; otherwise, 0. > + frozen > + 1 if the cgroup is frozen; otherwise, 0. > > cgroup.max.descendants > A read-write single value files. The default is "max". > @@ -897,6 +899,31 @@ All cgroup core files are prefixed with "cgroup." > A dying cgroup can consume system resources not exceeding > limits, which were active at the moment of cgroup deletion. > > + cgroup.freeze > + A read-write single value file which exists on non-root cgroups. > + Allowed values are "0" and "1". The default is "0". > + > + Writing "1" to the file causes freezing of the cgroup and all > + descendant cgroups. This means that all belonging processes will > + be stopped and will not run until the cgroup will be explicitly > + unfrozen. Freezing of the cgroup may take some time; when this action > + is completed, the "frozen" value in the cgroup.events control file > + will be updated to "1" and the corresponding notification will be > + issued. > + > + A cgroup can be frozen either by its own settings, or by settings > + of any ancestor cgroups. If any of ancestor cgroups is frozen, the > + cgroup will remain frozen. > + > + Processes in the frozen cgroup can be killed by a fatal signal. > + They also can enter and leave a frozen cgroup: either by an explicit > + move by a user, or if freezing of the cgroup races with fork(). > + If a process is moved to a frozen cgroup, it stops. If a process is > + moved out of a frozen cgroup, it becomes running. > + > + Frozen status of a cgroup doesn't affect any cgroup tree operations: > + it's possible to delete a frozen (and empty) cgroup, as well as > + create new sub-cgroups. > > Controllers > =========== > -- > 2.17.2 > -- Sincerely yours, Mike.
