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

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Message-ID: <d87cac0d-e395-a528-4c25-226399a09121@ascade.co.jp>
Date:   Fri, 18 May 2018 13:36:11 +0900
From:   TSUKADA Koutaro <tsukada@...ade.co.jp>
To:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Jonathan Corbet <corbet@....net>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <guro@...com>,
        David Rientjes <rientjes@...gle.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        Marc-Andre Lureau <marcandre.lureau@...hat.com>,
        Punit Agrawal <punit.agrawal@....com>,
        Dan Williams <dan.j.williams@...el.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, cgroups@...r.kernel.org, tsukada@...ade.co.jp
Subject: [PATCH v2 4/7] mm, sysctl: make charging surplus hugepages
 controllable

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

Signed-off-by: TSUKADA Koutaro <tsukada@...ade.co.jp>
---
 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