From: Bobby Eshleman <bobbyeshleman@meta.com>

Update the vsock child_ns_mode documentation to include the new
write-once semantics of setting child_ns_mode. The semantics are
implemented in a preceding patch in this series.

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
Changes in v3:
- update language to clarify language that first value is locked, but subsequent
  writes succeed.
---
 Documentation/admin-guide/sysctl/net.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
index c10530624f1e..3b2ad61995d4 100644
--- a/Documentation/admin-guide/sysctl/net.rst
+++ b/Documentation/admin-guide/sysctl/net.rst
@@ -594,6 +594,9 @@ Values:
 	  their sockets will only be able to connect within their own
 	  namespace.
 
+The first write to ``child_ns_mode`` locks its value. Subsequent writes of the
+same value succeed, but writing a different value returns ``-EBUSY``.
+
 Changing ``child_ns_mode`` only affects namespaces created after the change;
 it does not modify the current namespace or any existing children.
 

-- 
2.47.3

On Mon, Feb 23, 2026 at 02:38:34PM -0800, Bobby Eshleman wrote:
>From: Bobby Eshleman <bobbyeshleman@meta.com>
>
>Update the vsock child_ns_mode documentation to include the new
>write-once semantics of setting child_ns_mode. The semantics are
>implemented in a preceding patch in this series.
>
>Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
>---
>Changes in v3:
>- update language to clarify language that first value is locked, but subsequent
>  writes succeed.
>---
> Documentation/admin-guide/sysctl/net.rst | 3 +++
> 1 file changed, 3 insertions(+)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/Documentation/admin-guide/sysctl/net.rst b/Documentation/admin-guide/sysctl/net.rst
>index c10530624f1e..3b2ad61995d4 100644
>--- a/Documentation/admin-guide/sysctl/net.rst
>+++ b/Documentation/admin-guide/sysctl/net.rst
>@@ -594,6 +594,9 @@ Values:
> 	  their sockets will only be able to connect within their own
> 	  namespace.
>
>+The first write to ``child_ns_mode`` locks its value. Subsequent writes of the
>+same value succeed, but writing a different value returns ``-EBUSY``.
>+
> Changing ``child_ns_mode`` only affects namespaces created after the change;
> it does not modify the current namespace or any existing children.
>
>
>-- 
>2.47.3
>