[PATCH 4/5] Add sysctl for default hstate nodes_allowed.

[Lee Schermerhorn <lee.schermerhorn@hp.com>]

[PATCH 4/5] add sysctl for default hstate nodes_allowed.

Against:  17may09 mmotm

This patch adds a sysctl -- /proc/sys/vm/hugepages_nodes_allowed --
to set/query the default hstate's nodes_allowed.  I don't know
that this patch is required, given that we have the per hstate
controls in /sys/kernel/mm/hugepages/*. However, we've added sysctls
for other recent hugepages controls, like nr_overcommit_hugepages,
so I've followed that convention.

Factor the formatting of the nodes_allowed mask out of nodes_allowed_show()
for use by both that function and the hugetlb_nodes_allowed_handler().

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp>

 include/linux/hugetlb.h |    1 +
 kernel/sysctl.c         |    8 ++++++++
 mm/hugetlb.c            |   43 ++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 47 insertions(+), 5 deletions(-)

Index: linux-2.6.30-rc8-mmotm-090603-1633/include/linux/hugetlb.h
===================================================================
--- linux-2.6.30-rc8-mmotm-090603-1633.orig/include/linux/hugetlb.h	2009-06-04 12:59:32.000000000 -0400
+++ linux-2.6.30-rc8-mmotm-090603-1633/include/linux/hugetlb.h	2009-06-04 12:59:35.000000000 -0400
@@ -22,6 +22,7 @@ void reset_vma_resv_huge_pages(struct vm
 int hugetlb_sysctl_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int hugetlb_overcommit_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int hugetlb_treat_movable_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
+int hugetlb_nodes_allowed_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
 int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *, struct vm_area_struct *);
 int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, struct page **, struct vm_area_struct **, unsigned long *, int *, int, int);
 void unmap_hugepage_range(struct vm_area_struct *,
Index: linux-2.6.30-rc8-mmotm-090603-1633/kernel/sysctl.c
===================================================================
--- linux-2.6.30-rc8-mmotm-090603-1633.orig/kernel/sysctl.c	2009-06-04 12:59:26.000000000 -0400
+++ linux-2.6.30-rc8-mmotm-090603-1633/kernel/sysctl.c	2009-06-04 12:59:35.000000000 -0400
@@ -1108,6 +1108,14 @@ static struct ctl_table vm_table[] = {
 		.extra1		= (void *)&hugetlb_zero,
 		.extra2		= (void *)&hugetlb_infinity,
 	},
+	{
+		.ctl_name	= CTL_UNNUMBERED,
+		.procname	= "hugepages_nodes_allowed",
+		.data		= NULL,
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= &hugetlb_nodes_allowed_handler,
+	},
 #endif
 	{
 		.ctl_name	= VM_LOWMEM_RESERVE_RATIO,
Index: linux-2.6.30-rc8-mmotm-090603-1633/mm/hugetlb.c
===================================================================
--- linux-2.6.30-rc8-mmotm-090603-1633.orig/mm/hugetlb.c	2009-06-04 12:59:33.000000000 -0400
+++ linux-2.6.30-rc8-mmotm-090603-1633/mm/hugetlb.c	2009-06-04 12:59:35.000000000 -0400
@@ -1354,19 +1354,27 @@ static ssize_t nr_overcommit_hugepages_s
 }
 HSTATE_ATTR(nr_overcommit_hugepages);
 
-static ssize_t nodes_allowed_show(struct kobject *kobj,
-					struct kobj_attribute *attr, char *buf)
+static int format_hstate_nodes_allowed(struct hstate *h, char *buf,
+					size_t buflen)
 {
-	struct hstate *h = kobj_to_hstate(kobj);
 	int len = 3;
 
 	if (h->nodes_allowed == &node_online_map)
 		strcpy(buf, "all");
 	else
-		len = nodelist_scnprintf(buf, PAGE_SIZE,
+		len = nodelist_scnprintf(buf, buflen,
 					*h->nodes_allowed);
+	return len;
+
+}
+
+static ssize_t nodes_allowed_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	struct hstate *h = kobj_to_hstate(kobj);
+	int len =  format_hstate_nodes_allowed(h, buf, PAGE_SIZE);
 
-	if (len)
+	if (len && (len +1) < PAGE_SIZE)
 		buf[len++] = '\n';
 
 	return len;
@@ -1684,6 +1692,31 @@ int hugetlb_overcommit_handler(struct ct
 	return 0;
 }
 
+#define NODES_ALLOWED_MAX 64
+int hugetlb_nodes_allowed_handler(struct ctl_table *table, int write,
+			struct file *file, void __user *buffer,
+			size_t *length, loff_t *ppos)
+{
+	struct hstate *h = &default_hstate;
+	int ret = 0;
+
+	if (write) {
+		(void)set_hstate_nodes_allowed(h, buffer, 1);
+	} else {
+		char buf[NODES_ALLOWED_MAX];
+		struct ctl_table tbl = {
+			.data = buf,
+			.maxlen = NODES_ALLOWED_MAX,
+		};
+		int len =  format_hstate_nodes_allowed(h, buf, sizeof(buf));
+
+		if (len)
+			ret = proc_dostring(&tbl, write, file, buffer,
+						 length, ppos);
+	}
+	return ret;
+}
+
 #endif /* CONFIG_SYSCTL */
 
 void hugetlb_report_meminfo(struct seq_file *m)

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