[PATCH v7 5/5] docs: proc: add documentation about relaxing visibility restrictions

Alexey Gladkov
2026-01-13T09:21:25Z

Signed-off-by: Alexey Gladkov <legion@kernel.org>
---
Documentation/filesystems/proc.rst | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index c8864fcbdec7..3acf178c1202 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -2417,7 +2417,8 @@ so will give an `-EBUSY` error).
If user namespaces are in use, the kernel additionally checks the instances of
procfs available to the mounter and will not allow procfs to be mounted if:

- 1. This mount is not fully visible.
+ 1. This mount is not fully visible unless the new procfs is going to be
+ mounted with subset=pid option.

a. It's root directory is not the root directory of the filesystem.
b. If any file or non-empty procfs directory is hidden by another mount.
--
2.52.0