docs: namespace: Tweak and reword resource control doc

Fix the document title and reword the phrasing to active voice.

Signed-off-by: Joel Savitz <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Jonathan Corbet <[email protected]>

Author: theyoyojo

Documentation/admin-guide/namespaces/resource-control.rst

@@ -1,17 +1,17 @@
-===========================
-Namespaces research control
-===========================
+====================================
+User namespaces and resource control
+====================================
 
-There are a lot of kinds of objects in the kernel that don't have
-individual limits or that have limits that are ineffective when a set
-of processes is allowed to switch user ids.  With user namespaces
-enabled in a kernel for people who don't trust their users or their
-users programs to play nice this problems becomes more acute.
+The kernel contains many kinds of objects that either don't have
+individual limits or that have limits which are ineffective when
+a set of processes is allowed to switch their UID. On a system
+where the admins don't trust their users or their users' programs,
+user namespaces expose the system to potential misuse of resources.
 
-Therefore it is recommended that memory control groups be enabled in
-kernels that enable user namespaces, and it is further recommended
-that userspace configure memory control groups to limit how much
-memory user's they don't trust to play nice can use.
+In order to mitigate this, we recommend that admins enable memory
+control groups on any system that enables user namespaces.
+Furthermore, we recommend that admins configure the memory control
+groups to limit the maximum memory usable by any untrusted user.
 
 Memory control groups can be configured by installing the libcgroup
 package present on most distros editing /etc/cgrules.conf,