Add a sysctl knob, '/proc/sys/vm/migrc_enable' to switch on/off migrc.
Signed-off-by: Byungchul Park <byungchul@xxxxxx>
---
mm/migrate.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 46 insertions(+), 2 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index badef3d89c6c..c57536a0b2a6 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -59,6 +59,48 @@
#include "internal.h"
#ifdef CONFIG_MIGRC
+static int sysctl_migrc_enable = 1;
+#ifdef CONFIG_SYSCTL
+static int sysctl_migrc_enable_handler(struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table t;
+ int err;
+ int enabled = sysctl_migrc_enable;
+
+ if (write && !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ t = *table;
+ t.data = &enabled;
+ err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
+ if (err < 0)
+ return err;
+ if (write)
+ sysctl_migrc_enable = enabled;
+ return err;
+}
+
+static struct ctl_table migrc_sysctls[] = {
+ {
+ .procname = "migrc_enable",
+ .data = NULL, /* filled in by handler */
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = sysctl_migrc_enable_handler,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+ {}
+};
+
+static int __init migrc_sysctl_init(void)
+{
+ register_sysctl_init("vm", migrc_sysctls);
+ return 0;
+}
+late_initcall(migrc_sysctl_init);
+#endif
/*
* TODO: Yeah, it's a non-sense magic number. This simple value manages
@@ -288,6 +330,7 @@ int migrc_pending_nr_in_zone(struct zone *z)
}
#else
+static const int sysctl_migrc_enable;
static inline bool migrc_src_pending(struct folio *f) { return false; }
static inline bool migrc_dst_pending(struct folio *f) { return false; }
static inline bool migrc_is_full(int nid) { return true; }
@@ -1878,8 +1921,9 @@ static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
!list_empty(from) && !list_is_singular(from));
- migrc_cond1 = (reason == MR_DEMOTION && current_is_kswapd()) ||
- (reason == MR_NUMA_MISPLACED);
+ migrc_cond1 = sysctl_migrc_enable &&
+ ((reason == MR_DEMOTION && current_is_kswapd()) ||
+ (reason == MR_NUMA_MISPLACED));
if (migrc_cond1)
migrc_req_start();
--
2.17.1
