mm: Support compiling out madvise and fadvise

Many embedded systems will not need these syscalls, and omitting them
saves space.  Add a new EXPERT config option CONFIG_ADVISE_SYSCALLS
(default y) to support compiling them out.

bloat-o-meter:
add/remove: 0/3 grow/shrink: 0/0 up/down: 0/-2250 (-2250)
function                                     old     new   delta
sys_fadvise64                                 57       -     -57
sys_fadvise64_64                             691       -    -691
sys_madvise                                 1502       -   -1502

Signed-off-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/init/Kconfig b/init/Kconfig
index e84c6423a2e5..782a65bf76ea 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1537,6 +1537,16 @@ config AIO
           by some high performance threaded applications. Disabling
           this option saves about 7k.
 
+config ADVISE_SYSCALLS
+        bool "Enable madvise/fadvise syscalls" if EXPERT
+        default y
+        help
+          This option enables the madvise and fadvise syscalls, used by
+          applications to advise the kernel about their future memory or file
+          usage, improving performance. If building an embedded system where no
+          applications use these syscalls, you can disable this option to save
+          space.
+
 config PCI_QUIRKS
         default y
         bool "Enable PCI quirk workarounds" if EXPERT