userfaultfd: avoid missing wakeups during refile in userfaultfd_read

[karo-tx-linux.git] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index ba1e6eaf4c36e72bdf29d0b683b9c118fb0b38db..161acd8bc56fc5cc5bcf0ecd830e9ffcfa574873 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -947,6 +947,22 @@ config CGROUP_FREEZER
          Provides a way to freeze and unfreeze all tasks in a
          cgroup.
 
+config CGROUP_PIDS
+       bool "PIDs cgroup subsystem"
+       help
+         Provides enforcement of process number limits in the scope of a
+         cgroup. Any attempt to fork more processes than is allowed in the
+         cgroup will fail. PIDs are fundamentally a global resource because it
+         is fairly trivial to reach PID exhaustion before you reach even a
+         conservative kmemcg limit. As a result, it is possible to grind a
+         system to halt without being limited by other cgroup policies. The
+         PIDs cgroup subsystem is designed to stop this from happening.
+
+         It should be noted that organisational operations (such as attaching
+         to a cgroup hierarchy will *not* be blocked by the PIDs subsystem),
+         since the PIDs limit only affects a process's ability to fork, not to
+         attach to a cgroup.
+
 config CGROUP_DEVICE
        bool "Device controller for cgroups"
        help
@@ -1560,6 +1576,17 @@ config ADVISE_SYSCALLS
          applications use these syscalls, you can disable this option to save
          space.
 
+config USERFAULTFD
+       bool "Enable userfaultfd() system call"
+       select ANON_INODES
+       default y
+       depends on MMU
+       help
+         Enable the userfaultfd() system call that allows to intercept and
+         handle page faults in userland.
+
+         If unsure, say Y.
+
 config PCI_QUIRKS
        default y
        bool "Enable PCI quirk workarounds" if EXPERT