1Documentation for /proc/sys/user/*	kernel version 4.9.0
2	(c) 2016		Eric Biederman <ebiederm@xmission.com>
3
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5
6This file contains the documentation for the sysctl files in
7/proc/sys/user.
8
9The files in this directory can be used to override the default
10limits on the number of namespaces and other objects that have
11per user per user namespace limits.
12
13The primary purpose of these limits is to stop programs that
14malfunction and attempt to create a ridiculous number of objects,
15before the malfunction becomes a system wide problem.  It is the
16intention that the defaults of these limits are set high enough that
17no program in normal operation should run into these limits.
18
19The creation of per user per user namespace objects are charged to
20the user in the user namespace who created the object and
21verified to be below the per user limit in that user namespace.
22
23The creation of objects is also charged to all of the users
24who created user namespaces the creation of the object happens
25in (user namespaces can be nested) and verified to be below the per user
26limits in the user namespaces of those users.
27
28This recursive counting of created objects ensures that creating a
29user namespace does not allow a user to escape their current limits.
30
31Currently, these files are in /proc/sys/user:
32
33- max_cgroup_namespaces
34
35  The maximum number of cgroup namespaces that any user in the current
36  user namespace may create.
37
38- max_ipc_namespaces
39
40  The maximum number of ipc namespaces that any user in the current
41  user namespace may create.
42
43- max_mnt_namespaces
44
45  The maximum number of mount namespaces that any user in the current
46  user namespace may create.
47
48- max_net_namespaces
49
50  The maximum number of network namespaces that any user in the
51  current user namespace may create.
52
53- max_pid_namespaces
54
55  The maximum number of pid namespaces that any user in the current
56  user namespace may create.
57
58- max_user_namespaces
59
60  The maximum number of user namespaces that any user in the current
61  user namespace may create.
62
63- max_uts_namespaces
64
65  The maximum number of user namespaces that any user in the current
66  user namespace may create.
67