From: Michal Koutný mkoutny@suse.com
[ Upstream commit 3c41382e920f1dd5c9f432948fe799c07af1cced ]
The configs that disable some v1 controllers would still allow mounting them but with no controller-specific files. (Making such hierarchies equivalent to named v1 hierarchies.) To achieve behavior consistent with actual out-compilation of a whole controller, the mounts should treat respective controllers as non-existent.
Wrap implementation into a helper function, leverage legacy_files to detect compiled out controllers. The effect is that mounts on v1 would fail and produce a message like: [ 1543.999081] cgroup: Unknown subsys name 'memory'
Signed-off-by: Michal Koutný mkoutny@suse.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/cgroup/cgroup-v1.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index b9dbf6bf2779d..784337694a4be 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -46,6 +46,12 @@ bool cgroup1_ssid_disabled(int ssid) return cgroup_no_v1_mask & (1 << ssid); }
+static bool cgroup1_subsys_absent(struct cgroup_subsys *ss) +{ + /* Check also dfl_cftypes for file-less controllers, i.e. perf_event */ + return ss->legacy_cftypes == NULL && ss->dfl_cftypes; +} + /** * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' * @from: attach to all cgroups of a given task @@ -932,7 +938,8 @@ int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param) if (ret != -ENOPARAM) return ret; for_each_subsys(ss, i) { - if (strcmp(param->key, ss->legacy_name)) + if (strcmp(param->key, ss->legacy_name) || + cgroup1_subsys_absent(ss)) continue; if (!cgroup_ssid_enabled(i) || cgroup1_ssid_disabled(i)) return invalfc(fc, "Disabled controller '%s'", @@ -1024,7 +1031,8 @@ static int check_cgroupfs_options(struct fs_context *fc) mask = ~((u16)1 << cpuset_cgrp_id); #endif for_each_subsys(ss, i) - if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i)) + if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i) && + !cgroup1_subsys_absent(ss)) enabled |= 1 << i;
ctx->subsys_mask &= enabled;