[PATCH] cgroup: Avoid warning when procfs is disabled

[PATCH] cgroup: Avoid warning when procfs is disabled

[Karl Mehltretter]

With CGROUPS=y and PROC_FS=n, proc_create_single() returns NULL and
cgroup initialization warns during every boot.

Only check creation of /proc/cgroups when procfs is enabled.

Fixes: 035f4f510583 ("cgroup: replace error handling in cgroup_init() with WARN_ON()s")
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
---
 kernel/cgroup/cgroup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 227d09704ca5..567afb75a4ec 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6612,7 +6612,9 @@ int __init cgroup_init(void)
 	WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
 	WARN_ON(register_filesystem(&cgroup_fs_type));
 	WARN_ON(register_filesystem(&cgroup2_fs_type));
-	WARN_ON(!proc_create_single("cgroups", 0, NULL, proc_cgroupstats_show));
+	if (IS_ENABLED(CONFIG_PROC_FS))
+		WARN_ON(!proc_create_single("cgroups", 0, NULL,
+					    proc_cgroupstats_show));
 #ifdef CONFIG_CPUSETS_V1
 	WARN_ON(register_filesystem(&cpuset_fs_type));
 #endif
-- 
2.53.0

Re: [PATCH] cgroup: Avoid warning when procfs is disabled

[Michal Koutný]

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On Mon, Oct 12, 2026 at 07:42:19AM +0200, Karl Mehltretter <kmehltretter@gmail.com> wrote:
> With CGROUPS=y and PROC_FS=n,

What is practical about this config? Is it real life usage?

> proc_create_single() returns NULL and
> cgroup initialization warns during every boot.
> 
> Only check creation of /proc/cgroups when procfs is enabled.

The dependency on CONFIG_PROC_FS is encoded in the
proc_create_single already, it's unfortunate that it returns a value
that signifies an error.
I'd prefer more generic fix that doesn't target cgroup_init()
specifically.

Thanks,
Michal

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