[PATCH V8 1/2] mm: compaction: move compaction sysctl to its own file

From: ye.xingchen
Date: Tue Mar 28 2023 - 02:46:47 EST

From: Minghao Chi <chi.minghao@xxxxxxxxxx>

This moves all compaction sysctls to its own file.

Move sysctl to where the functionality truly belongs to improve
readability, reduce merge conflicts, and facilitate maintenance.

I use x86_defconfig and linux-next-20230327 branch
$ make defconfig;make all -jn
CONFIG_COMPACTION=y

add/remove: 1/0 grow/shrink: 1/1 up/down: 350/-256 (94)
Function old new delta
vm_compaction - 320 +320
kcompactd_init 180 210 +30
vm_table 2112 1856 -256
Total: Before=21119987, After=21120081, chg +0.00%

Despite the addition of 94 bytes the patch still seems a worthwile
cleanup.

Link: https://lore.kernel.org/lkml/067f7347-ba10-5405-920c-0f5f985c84f4@xxxxxxx/
Signed-off-by: Minghao Chi <chi.minghao@xxxxxxxxxx>
---
include/linux/compaction.h | 7 ----
kernel/sysctl.c | 59 --------------------------
mm/compaction.c | 84 ++++++++++++++++++++++++++++++++------
3 files changed, 72 insertions(+), 78 deletions(-)

diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 52a9ff65faee..a6e512cfb670 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -81,13 +81,6 @@ static inline unsigned long compact_gap(unsigned int order)
}

#ifdef CONFIG_COMPACTION
-extern unsigned int sysctl_compaction_proactiveness;
-extern int sysctl_compaction_handler(struct ctl_table *table, int write,
- void *buffer, size_t *length, loff_t *ppos);
-extern int compaction_proactiveness_sysctl_handler(struct ctl_table *table,
- int write, void *buffer, size_t *length, loff_t *ppos);
-extern int sysctl_extfrag_threshold;
-extern int sysctl_compact_unevictable_allowed;

extern unsigned int extfrag_for_order(struct zone *zone, unsigned int order);
extern int fragmentation_index(struct zone *zone, unsigned int order);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 0a8a3c9c82e4..bfe53e835524 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -42,7 +42,6 @@
#include <linux/highuid.h>
#include <linux/writeback.h>
#include <linux/ratelimit.h>
-#include <linux/compaction.h>
#include <linux/hugetlb.h>
#include <linux/initrd.h>
#include <linux/key.h>
@@ -746,27 +745,6 @@ int proc_dointvec(struct ctl_table *table, int write, void *buffer,
return do_proc_dointvec(table, write, buffer, lenp, ppos, NULL, NULL);
}

-#ifdef CONFIG_COMPACTION
-static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table,
- int write, void *buffer, size_t *lenp, loff_t *ppos)
-{
- int ret, old;
-
- if (!IS_ENABLED(CONFIG_PREEMPT_RT) || !write)
- return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-
- old = *(int *)table->data;
- ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
- if (ret)
- return ret;
- if (old != *(int *)table->data)
- pr_warn_once("sysctl attribute %s changed by %s[%d]\n",
- table->procname, current->comm,
- task_pid_nr(current));
- return ret;
-}
-#endif
-
/**
* proc_douintvec - read a vector of unsigned integers
* @table: the sysctl table
@@ -2157,43 +2135,6 @@ static struct ctl_table vm_table[] = {
.extra1 = SYSCTL_ONE,
.extra2 = SYSCTL_FOUR,
},
-#ifdef CONFIG_COMPACTION
- {
- .procname = "compact_memory",
- .data = NULL,
- .maxlen = sizeof(int),
- .mode = 0200,
- .proc_handler = sysctl_compaction_handler,
- },
- {
- .procname = "compaction_proactiveness",
- .data = &sysctl_compaction_proactiveness,
- .maxlen = sizeof(sysctl_compaction_proactiveness),
- .mode = 0644,
- .proc_handler = compaction_proactiveness_sysctl_handler,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE_HUNDRED,
- },
- {
- .procname = "extfrag_threshold",
- .data = &sysctl_extfrag_threshold,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE_THOUSAND,
- },
- {
- .procname = "compact_unevictable_allowed",
- .data = &sysctl_compact_unevictable_allowed,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax_warn_RT_change,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
- },
-
-#endif /* CONFIG_COMPACTION */
{
.procname = "min_free_kbytes",
.data = &min_free_kbytes,
diff --git a/mm/compaction.c b/mm/compaction.c
index e689d66cedf4..3dfdb84b9c98 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1728,7 +1728,14 @@ typedef enum {
* Allow userspace to control policy on scanning the unevictable LRU for
* compactable pages.
*/
-int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNEVICTABLE_DEFAULT;
+static int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNEVICTABLE_DEFAULT;
+/*
+ * Tunable for proactive compaction. It determines how
+ * aggressively the kernel should compact memory in the
+ * background. It takes values in the range [0, 100].
+ */
+static unsigned int __read_mostly sysctl_compaction_proactiveness = 20;
+static int sysctl_extfrag_threshold = 500;

static inline void
update_fast_start_pfn(struct compact_control *cc, unsigned long pfn)
@@ -2584,8 +2591,6 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
return ret;
}

-int sysctl_extfrag_threshold = 500;
-
/**
* try_to_compact_pages - Direct compact to satisfy a high-order allocation
* @gfp_mask: The GFP mask of the current allocation
@@ -2742,14 +2747,7 @@ static void compact_nodes(void)
compact_node(nid);
}

-/*
- * Tunable for proactive compaction. It determines how
- * aggressively the kernel should compact memory in the
- * background. It takes values in the range [0, 100].
- */
-unsigned int __read_mostly sysctl_compaction_proactiveness = 20;
-
-int compaction_proactiveness_sysctl_handler(struct ctl_table *table, int write,
+static int compaction_proactiveness_sysctl_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
int rc, nid;
@@ -2779,7 +2777,7 @@ int compaction_proactiveness_sysctl_handler(struct ctl_table *table, int write,
* This is the entry point for compacting all nodes via
* /proc/sys/vm/compact_memory
*/
-int sysctl_compaction_handler(struct ctl_table *table, int write,
+static int sysctl_compaction_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
if (write)
@@ -3075,6 +3073,65 @@ static int kcompactd_cpu_online(unsigned int cpu)
return 0;
}

+static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table,
+ int write, void *buffer, size_t *lenp, loff_t *ppos)
+{
+ int ret, old;
+
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT) || !write)
+ return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+
+ old = *(int *)table->data;
+ ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+ if (ret)
+ return ret;
+ if (old != *(int *)table->data)
+ pr_warn_once("sysctl attribute %s changed by %s[%d]\n",
+ table->procname, current->comm,
+ task_pid_nr(current));
+ return ret;
+}
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table vm_compaction[] = {
+ {
+ .procname = "compact_memory",
+ .data = NULL,
+ .maxlen = sizeof(int),
+ .mode = 0200,
+ .proc_handler = sysctl_compaction_handler,
+ },
+ {
+ .procname = "compaction_proactiveness",
+ .data = &sysctl_compaction_proactiveness,
+ .maxlen = sizeof(sysctl_compaction_proactiveness),
+ .mode = 0644,
+ .proc_handler = compaction_proactiveness_sysctl_handler,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE_HUNDRED,
+ },
+ {
+ .procname = "extfrag_threshold",
+ .data = &sysctl_extfrag_threshold,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE_THOUSAND,
+ },
+ {
+ .procname = "compact_unevictable_allowed",
+ .data = &sysctl_compact_unevictable_allowed,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax_warn_RT_change,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+ { }
+};
+#endif
+
static int __init kcompactd_init(void)
{
int nid;
@@ -3090,6 +3147,9 @@ static int __init kcompactd_init(void)

for_each_node_state(nid, N_MEMORY)
kcompactd_run(nid);
+#ifdef CONFIG_SYSCTL
+ register_sysctl_init("vm", vm_compaction);
+#endif
return 0;
}
subsys_initcall(kcompactd_init)
--
2.25.1