userfaultfd: buildsystem activation

This allows to select the userfaultfd during configuration to build it.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/Makefile b/fs/Makefile
index 09e051fefc5b4ed5b6759c9e191c2cca4cd496e7..f79cf4043e60d9c854adfce1634164e1a0fef53f 100644 (file)
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_ANON_INODES)     += anon_inodes.o
 obj-$(CONFIG_SIGNALFD)         += signalfd.o
 obj-$(CONFIG_TIMERFD)          += timerfd.o
 obj-$(CONFIG_EVENTFD)          += eventfd.o
+obj-$(CONFIG_USERFAULTFD)      += userfaultfd.o
 obj-$(CONFIG_AIO)               += aio.o
 obj-$(CONFIG_FS_DAX)           += dax.o
 obj-$(CONFIG_FILE_LOCKING)      += locks.o

diff --git a/init/Kconfig b/init/Kconfig
index bb9b4dd55889f0605b07ddfc73cc105d72b18908..161acd8bc56fc5cc5bcf0ecd830e9ffcfa574873 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1576,6 +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