On 11/2/2026 9:37 AM, Baoquan He wrote:
On 10/31/26 at 05:00pm, Ridong Chen wrote:
From: Ridong Chen <[email protected]>
Move include/trace/events/vmscan.h to mm/trace_vmscan.h so that the
tracepoints can be extended to reference vmscan-internal structures such
as struct scan_control, which is not visible outside mm/. This mirrors
what several other subsystems already do with their trace headers (e.g.
fs/fuse/fuse_trace.h, fs/gfs2/trace_gfs2.h, fs/lockd/trace.h). As they
do, set TRACE_INCLUDE_PATH to "." and add mm/ to the include path of
vmscan.o, the only user that defines CREATE_TRACE_POINTS.
No functional change.
Signed-off-by: Ridong Chen <[email protected]>
Reviewed-by: Barry Song <[email protected]>
---
MAINTAINERS | 2 ++
mm/Makefile | 1 +
mm/shrinker.c | 2 +-
include/trace/events/vmscan.h => mm/trace_vmscan.h | 4 ++++
mm/vmscan.c | 2 +-
5 files changed, 9 insertions(+), 2 deletions(-)
rename include/trace/events/vmscan.h => mm/trace_vmscan.h (99%)
diff --git a/MAINTAINERS b/MAINTAINERS
index aaf2825ac945..2ad01107fa05 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17653,6 +17653,7 @@ F: Documentation/admin-guide/mm/multigen_lru.rst
F: Documentation/mm/multigen_lru.rst
F: include/linux/mm_inline.h
F: include/linux/mmzone.h
+F: mm/trace_vmscan.h
F: mm/vmscan.c
F: mm/workingset.c
@@ -17802,6 +17803,7 @@ R: Shakeel Butt <[email protected]>
R: Lorenzo Stoakes <[email protected]>
L: [email protected]
S: Maintained
+F: mm/trace_vmscan.h
F: mm/vmscan.c
F: mm/workingset.c
diff --git a/mm/Makefile b/mm/Makefile
index 2a3ec53d62ee..277b97f7f8d7 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -32,6 +32,7 @@ KCOV_INSTRUMENT_vmstat.o := n
KCOV_INSTRUMENT_failslab.o := n
CFLAGS_init-mm.o += -Wno-override-init
+CFLAGS_vmscan.o += -I$(src)
One nit:
Does it really need the above line? It affects mm/shrinker.c too, did your
shrinker.o building fail?
Seems it's redundant because kbuild adds -I$(src) -I$(obj) for every object
in the directory since commit cdd750bfb1f7 ("kbuild: remove 'addtree' and
'flags' magic for header search paths"). Please correct me if I am
wrong.
Hi Baoquan,
Thanks for the review.
The line is needed for vmscan.o, and mm/shrinker.c is fine without it,
because the two files include trace_vmscan.h in different ways.
mm/shrinker.c only does a plain #include "trace_vmscan.h". The lookup
starts from mm/, where the header lives, so no -I is needed.
mm/vmscan.c defines CREATE_TRACE_POINTS before including the header.
In that case <trace/define_trace.h>, included at the end of
trace_vmscan.h, includes the header again to generate the tracepoint
definitions:
#include TRACE_INCLUDE(TRACE_INCLUDE_FILE) /* -> "./trace_vmscan.h" */
This #include is in include/trace/define_trace.h, so the lookup starts
from include/trace/ and only finds the header through -I. Without the
flag, vmscan.o fails to build:
./include/trace/define_trace.h:118:42: fatal error: ./trace_vmscan.h: No such
file or directory
As for cdd750bfb1f7, it doesn't add -I$(src) for every build. kbuild
only adds -I$(src) -I$(obj) automatically when building with O=
(see "ifdef building_out_of_srctree" in scripts/Makefile.lib). So
with O= the line is indeed redundant and vmscan.o builds fine without
it, but a plain in-tree "make" fails with the error above. The
explicit flag keeps both working.
To be honest, I had the same worry at first: I thought every .c file
that includes the header would need a Makefile change. That's why v3
used a relative TRACE_INCLUDE_PATH (../../mm) instead. Steven corrected
me and pointed out that the proper way is TRACE_INCLUDE_PATH "." plus
-I$(src) for the one object that defines CREATE_TRACE_POINTS [1]. That
turned out to need only this one line. Thanks again to Steven for
that.
[1] https://lore.kernel.org/all/[email protected]/
Other than the nit, this patch looks good to me,
Reviewed-by: Baoquan He <[email protected]>
Thanks.
mmu-y := nommu.o
mmu-$(CONFIG_MMU) := highmem.o memory.o mincore.o \
diff --git a/mm/shrinker.c b/mm/shrinker.c
index 4fb424e721bc..4fbdade6d2f6 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -3,7 +3,7 @@
#include <linux/rwsem.h>
#include <linux/shrinker.h>
#include <linux/rculist.h>
-#include <trace/events/vmscan.h>
+#include "trace_vmscan.h"
#include "internal.h"
diff --git a/include/trace/events/vmscan.h b/mm/trace_vmscan.h
similarity index 99%
rename from include/trace/events/vmscan.h
rename to mm/trace_vmscan.h
index 8a872990b4be..ad90f0e9bf2e 100644
--- a/include/trace/events/vmscan.h
+++ b/mm/trace_vmscan.h
@@ -648,4 +648,8 @@ TRACE_EVENT(mm_vmscan_kswapd_clear_hopeless,
#endif /* _TRACE_VMSCAN_H */
/* This part must be outside protection */
+#undef TRACE_INCLUDE_FILE
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#define TRACE_INCLUDE_FILE trace_vmscan
#include <trace/define_trace.h>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9959ca158ce8..79d2d614afd0 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -71,7 +71,7 @@
#include "swap.h"
#define CREATE_TRACE_POINTS
-#include <trace/events/vmscan.h>
+#include "trace_vmscan.h"
struct scan_control {
/* How many pages shrink_list() should reclaim */
--
2.43.0
--
Best regards
Ridong
