kevin/linux
1
Fork 0
Code

cgroup: Disallow mounting v1 hierarchies without controller implementation

Browse Source 
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>
This commit is contained in:
Michal Koutný 2024-09-09 18:32:22 +02:00 committed by Tejun Heo
parent 659f90f863
commit 3c41382e92
1 changed files with 10 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
kernel/cgroup/cgroup-v1.c
View File

@ -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;