samples: introduce new samples subdir for cgroup

Patch series "samples: introduce cgroup events listeners", v3.

To begin with, this patch series relocates the cgroup example code to the
samples/cgroup directory, which is the appropriate location for such code
snippets.

Furthermore, a new memcg events listener is introduced.  This listener is
a simple yet effective tool for monitoring memory events and managing
counter changes during runtime.

Additionally, as per Andrew Morton's suggestion, a helpful reminder
comment is included in the memcontrol implementation.  This comment serves
to ensure that the samples code is updated whenever new events are added.

This patch (of 3):

Move the cgroup_event_listener for cgroup v1 to the samples directory.
This suggestion was proposed by Andrew Morton during the discussion [1].

Link: https://lore.kernel.org/all/20231106140934.3f5d4960141562fe8da53906@linux-foundation.org/
Link: https://lkml.kernel.org/r/20231123071945.25811-1-ddrokosov@salutedevices.com
Link: https://lkml.kernel.org/r/20231123071945.25811-2-ddrokosov@salutedevices.com
Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/MAINTAINERS b/MAINTAINERS
index 5c9d3d8546714a8a46fed7fd9384fbede2b9e4c7..6f5d6962d26d1c3098cf30787b3241a92ae1467c 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5339,6 +5339,7 @@ L:        linux-mm@kvack.org
 S:     Maintained
 F:     mm/memcontrol.c
 F:     mm/swap_cgroup.c
+F:     samples/cgroup/*
 F:     tools/testing/selftests/cgroup/memcg_protection.m
 F:     tools/testing/selftests/cgroup/test_hugetlb_memcg.c
 F:     tools/testing/selftests/cgroup/test_kmem.c

diff --git a/samples/Kconfig b/samples/Kconfig
index b0ddf5f3673887174da5a0a5c1d46f51003ebdf2..b288d9991d27ae9f064e388fb691ff0d6f0c2ff8 100644 (file)
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -285,6 +285,12 @@ config SAMPLE_KMEMLEAK
           Build a sample program which have explicitly leaks memory to test
           kmemleak
 
+config SAMPLE_CGROUP
+       bool "Build cgroup sample code"
+       depends on CGROUPS && CC_CAN_LINK && HEADERS_INSTALL
+       help
+         Build samples that demonstrate the usage of the cgroup API.
+
 source "samples/rust/Kconfig"
 
 endif # SAMPLES

diff --git a/samples/Makefile b/samples/Makefile
index 0a551c2b33f430d639ad6f420b1e391a0599ccf7..b85fa64390c515e14224e07918688b04eabb54b3 100644 (file)
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -3,6 +3,7 @@
 
 subdir-$(CONFIG_SAMPLE_AUXDISPLAY)     += auxdisplay
 subdir-$(CONFIG_SAMPLE_ANDROID_BINDERFS) += binderfs
+subdir-$(CONFIG_SAMPLE_CGROUP) += cgroup
 obj-$(CONFIG_SAMPLE_CONFIGFS)          += configfs/
 obj-$(CONFIG_SAMPLE_CONNECTOR)         += connector/
 obj-$(CONFIG_SAMPLE_FANOTIFY_ERROR)    += fanotify/

diff --git a/samples/cgroup/Makefile b/samples/cgroup/Makefile
new file mode 100644 (file)
index 0000000..deef453
--- /dev/null
+++ b/samples/cgroup/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+
+userprogs-always-y += cgroup_event_listener
+
+userccflags += -I usr/include

diff --git a/tools/cgroup/cgroup_event_listener.c b/samples/cgroup/cgroup_event_listener.c
similarity index 100%
rename from tools/cgroup/cgroup_event_listener.c
rename to samples/cgroup/cgroup_event_listener.c

diff --git a/tools/cgroup/Makefile b/tools/cgroup/Makefile
deleted file mode 100644 (file)
index ffca068..0000000
--- a/tools/cgroup/Makefile
+++ /dev/null
@@ -1,11 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0
-# Makefile for cgroup tools
-
-CFLAGS = -Wall -Wextra
-
-all: cgroup_event_listener
-%: %.c
-       $(CC) $(CFLAGS) -o $@ $^
-
-clean:
-       $(RM) cgroup_event_listener