mm: add tracepoints to ksm

This adds the following tracepoints to ksm:
- start / stop scan
- ksm enter / exit
- merge a page
- merge a page with ksm
- remove a page
- remove a rmap item

This patch has been split off from the RFC patch series "mm:
process/cgroup ksm support".

---
 mm/Makefile    |   1 +
 mm/ksm.c       |  62 ++++--------
 mm/ksm.h       |  45 +++++++++
 mm/ksm_trace.h | 258 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 324 insertions(+), 42 deletions(-)
 create mode 100644 mm/ksm.h
 create mode 100644 mm/ksm_trace.h

index 3a08f5d7b178..1cb6ae4404f2 100644
@@ -35,6 +35,7 @@ KCOV_INSTRUMENT_failslab.o := n
 
 CFLAGS_init-mm.o += $(call cc-disable-warning, override-init)
 CFLAGS_init-mm.o += $(call cc-disable-warning, initializer-overrides)
+CFLAGS_ksm.o		:= -I$(src)
 
 mmu-y			:= nommu.o
 mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \

2.34.1