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>
diff --git a/init/Kconfig b/init/Kconfig
index e84c642..782a65b 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1537,6 +1537,16 @@
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
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 391d4dd..d4709d4 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -156,6 +156,9 @@
cond_syscall(compat_sys_process_vm_readv);
cond_syscall(compat_sys_process_vm_writev);
cond_syscall(sys_uselib);
+cond_syscall(sys_fadvise64);
+cond_syscall(sys_fadvise64_64);
+cond_syscall(sys_madvise);
/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);
diff --git a/mm/Makefile b/mm/Makefile
index 632ae77..fe7a053 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -3,7 +3,7 @@
#
mmu-y := nommu.o
-mmu-$(CONFIG_MMU) := fremap.o gup.o highmem.o madvise.o memory.o mincore.o \
+mmu-$(CONFIG_MMU) := fremap.o gup.o highmem.o memory.o mincore.o \
mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
vmalloc.o pagewalk.o pgtable-generic.o
@@ -11,7 +11,7 @@
mmu-$(CONFIG_MMU) += process_vm_access.o
endif
-obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
+obj-y := filemap.o mempool.o oom_kill.o \
maccess.o page_alloc.o page-writeback.o \
readahead.o swap.o truncate.o vmscan.o shmem.o \
util.o mmzone.o vmstat.o backing-dev.o \
@@ -28,6 +28,9 @@
obj-y += bootmem.o
endif
+ifdef CONFIG_MMU
+ obj-$(CONFIG_ADVISE_SYSCALLS) += fadvise.o madvise.o
+endif
obj-$(CONFIG_HAVE_MEMBLOCK) += memblock.o
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o