[PATCH v2 4/7] mm, sysctl: make charging surplus hugepages controllable

[TSUKADA Koutaro <tsukada@xxxxxxxxxxxx>]

Make the default hugetlb surplus hugepage controlable by
/proc/sys/vm/charge_surplus_hugepages.

Signed-off-by: TSUKADA Koutaro <tsukada@xxxxxxxxxxxx>
---
 include/linux/hugetlb.h |    2 ++
 kernel/sysctl.c         |    7 +++++++
 mm/hugetlb.c            |   21 +++++++++++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 33fe5be..9314b07 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -80,6 +80,8 @@ struct hugepage_subpool *hugepage_new_subpool(struct hstate *h, long max_hpages,
 void reset_vma_resv_huge_pages(struct vm_area_struct *vma);
 int hugetlb_sysctl_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
 int hugetlb_overcommit_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
+int hugetlb_charge_surplus_handler(struct ctl_table *, int, void __user *,
+					size_t *, loff_t *);
 int hugetlb_treat_movable_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);

 #ifdef CONFIG_NUMA
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6a78cf7..d562d64 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1394,6 +1394,13 @@ static int sysrq_sysctl_handler(struct ctl_table *table, int write,
 		.mode		= 0644,
 		.proc_handler	= hugetlb_overcommit_handler,
 	},
+	{
+		.procname	= "charge_surplus_hugepages",
+		.data		= NULL,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= hugetlb_charge_surplus_handler,
+	},
 #endif
 	{
 		.procname	= "lowmem_reserve_ratio",
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2e7b543..9a9549c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3069,6 +3069,27 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write,
 	return ret;
 }

+int hugetlb_charge_surplus_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos)
+{
+	struct hstate *h = &default_hstate;
+	int tmp, ret;
+
+	if (!hugepages_supported())
+		return -EOPNOTSUPP;
+
+	tmp = h->charge_surplus_huge_pages ? 1 : 0;
+	table->data = &tmp;
+	table->maxlen = sizeof(int);
+	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+	if (ret)
+		goto out;
+
+	if (write)
+		h->charge_surplus_huge_pages = tmp ? true : false;
+out:
+	return ret;
+}
 #endif /* CONFIG_SYSCTL */

 void hugetlb_report_meminfo(struct seq_file *m)

--
Tsukada