hugetlb: new sysfs interface

Provide new hugepages user APIs that are more suited to multiple hstates
in sysfs.  There is a new directory, /sys/kernel/hugepages.  Underneath
that directory there will be a directory per-supported hugepage size,
e.g.:

/sys/kernel/hugepages/hugepages-64kB
/sys/kernel/hugepages/hugepages-16384kB
/sys/kernel/hugepages/hugepages-16777216kB

corresponding to 64k, 16m and 16g respectively.  Within each
hugepages-size directory there are a number of files, corresponding to the
tracked counters in the hstate, e.g.:

/sys/kernel/hugepages/hugepages-64/nr_hugepages
/sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages
/sys/kernel/hugepages/hugepages-64/free_hugepages
/sys/kernel/hugepages/hugepages-64/resv_hugepages
/sys/kernel/hugepages/hugepages-64/surplus_hugepages

Of these files, the first two are read-write and the latter three are
read-only.  The size of the hugepage being manipulated is trivially
deducible from the enclosing directory and is always expressed in kB (to
match meminfo).

[dave@linux.vnet.ibm.com: fix build]
[nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel]
[nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency]
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 222 insertions, 66 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4cf7a90e9140..bb49ce5d0067 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -14,6 +14,7 @@
 #include <linux/mempolicy.h>
 #include <linux/cpuset.h>
 #include <linux/mutex.h>
+#include <linux/sysfs.h>
 
 #include <asm/page.h>
 #include <asm/pgtable.h>
@@ -942,72 +943,6 @@ static void __init report_hugepages(void)
         }
 }
 
-static int __init hugetlb_init(void)
-{
-        BUILD_BUG_ON(HPAGE_SHIFT == 0);
-
-        if (!size_to_hstate(HPAGE_SIZE)) {
-                hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
-                parsed_hstate->max_huge_pages = default_hstate_max_huge_pages;
-        }
-        default_hstate_idx = size_to_hstate(HPAGE_SIZE) - hstates;
-
-        hugetlb_init_hstates();
-
-        report_hugepages();
-
-        return 0;
-}
-module_init(hugetlb_init);
-
-/* Should be called on processing a hugepagesz=... option */
-void __init hugetlb_add_hstate(unsigned order)
-{
-        struct hstate *h;
-        if (size_to_hstate(PAGE_SIZE << order)) {
-                printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
-                return;
-        }
-        BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
-        BUG_ON(order == 0);
-        h = &hstates[max_hstate++];
-        h->order = order;
-        h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
-        hugetlb_init_one_hstate(h);
-        parsed_hstate = h;
-}
-
-static int __init hugetlb_setup(char *s)
-{
-        unsigned long *mhp;
-
-        /*
-         * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
-         * so this hugepages= parameter goes to the "default hstate".
-         */
-        if (!max_hstate)
-                mhp = &default_hstate_max_huge_pages;
-        else
-                mhp = &parsed_hstate->max_huge_pages;
-
-        if (sscanf(s, "%lu", mhp) <= 0)
-                *mhp = 0;
-
-        return 1;
-}
-__setup("hugepages=", hugetlb_setup);
-
-static unsigned int cpuset_mems_nr(unsigned int *array)
-{
-        int node;
-        unsigned int nr = 0;
-
-        for_each_node_mask(node, cpuset_current_mems_allowed)
-                nr += array[node];
-
-        return nr;
-}
-
 #ifdef CONFIG_SYSCTL
 #ifdef CONFIG_HIGHMEM
 static void try_to_free_low(struct hstate *h, unsigned long count)
@@ -1105,6 +1040,227 @@ out:
         return ret;
 }
 
+#define HSTATE_ATTR_RO(_name) \
+        static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
+
+#define HSTATE_ATTR(_name) \
+        static struct kobj_attribute _name##_attr = \
+                __ATTR(_name, 0644, _name##_show, _name##_store)
+
+static struct kobject *hugepages_kobj;
+static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
+
+static struct hstate *kobj_to_hstate(struct kobject *kobj)
+{
+        int i;
+        for (i = 0; i < HUGE_MAX_HSTATE; i++)
+                if (hstate_kobjs[i] == kobj)
+                        return &hstates[i];
+        BUG();
+        return NULL;
+}
+
+static ssize_t nr_hugepages_show(struct kobject *kobj,
+                                        struct kobj_attribute *attr, char *buf)
+{
+        struct hstate *h = kobj_to_hstate(kobj);
+        return sprintf(buf, "%lu\n", h->nr_huge_pages);
+}
+static ssize_t nr_hugepages_store(struct kobject *kobj,
+                struct kobj_attribute *attr, const char *buf, size_t count)
+{
+        int err;
+        unsigned long input;
+        struct hstate *h = kobj_to_hstate(kobj);
+
+        err = strict_strtoul(buf, 10, &input);
+        if (err)
+                return 0;
+
+        h->max_huge_pages = set_max_huge_pages(h, input);
+
+        return count;
+}
+HSTATE_ATTR(nr_hugepages);
+
+static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
+                                        struct kobj_attribute *attr, char *buf)
+{
+        struct hstate *h = kobj_to_hstate(kobj);
+        return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
+}
+static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
+                struct kobj_attribute *attr, const char *buf, size_t count)
+{
+        int err;
+        unsigned long input;
+        struct hstate *h = kobj_to_hstate(kobj);
+
+        err = strict_strtoul(buf, 10, &input);
+        if (err)
+                return 0;
+
+        spin_lock(&hugetlb_lock);
+        h->nr_overcommit_huge_pages = input;
+        spin_unlock(&hugetlb_lock);
+
+        return count;
+}
+HSTATE_ATTR(nr_overcommit_hugepages);
+
+static ssize_t free_hugepages_show(struct kobject *kobj,
+                                        struct kobj_attribute *attr, char *buf)
+{
+        struct hstate *h = kobj_to_hstate(kobj);
+        return sprintf(buf, "%lu\n", h->free_huge_pages);
+}
+HSTATE_ATTR_RO(free_hugepages);
+
+static ssize_t resv_hugepages_show(struct kobject *kobj,
+                                        struct kobj_attribute *attr, char *buf)
+{
+        struct hstate *h = kobj_to_hstate(kobj);
+        return sprintf(buf, "%lu\n", h->resv_huge_pages);
+}
+HSTATE_ATTR_RO(resv_hugepages);
+
+static ssize_t surplus_hugepages_show(struct kobject *kobj,
+                                        struct kobj_attribute *attr, char *buf)
+{
+        struct hstate *h = kobj_to_hstate(kobj);
+        return sprintf(buf, "%lu\n", h->surplus_huge_pages);
+}
+HSTATE_ATTR_RO(surplus_hugepages);
+
+static struct attribute *hstate_attrs[] = {
+        &nr_hugepages_attr.attr,
+        &nr_overcommit_hugepages_attr.attr,
+        &free_hugepages_attr.attr,
+        &resv_hugepages_attr.attr,
+        &surplus_hugepages_attr.attr,
+        NULL,
+};
+
+static struct attribute_group hstate_attr_group = {
+        .attrs = hstate_attrs,
+};
+
+static int __init hugetlb_sysfs_add_hstate(struct hstate *h)
+{
+        int retval;
+
+        hstate_kobjs[h - hstates] = kobject_create_and_add(h->name,
+                                                        hugepages_kobj);
+        if (!hstate_kobjs[h - hstates])
+                return -ENOMEM;
+
+        retval = sysfs_create_group(hstate_kobjs[h - hstates],
+                                                        &hstate_attr_group);
+        if (retval)
+                kobject_put(hstate_kobjs[h - hstates]);
+
+        return retval;
+}
+
+static void __init hugetlb_sysfs_init(void)
+{
+        struct hstate *h;
+        int err;
+
+        hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
+        if (!hugepages_kobj)
+                return;
+
+        for_each_hstate(h) {
+                err = hugetlb_sysfs_add_hstate(h);
+                if (err)
+                        printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
+                                                                h->name);
+        }
+}
+
+static void __exit hugetlb_exit(void)
+{
+        struct hstate *h;
+
+        for_each_hstate(h) {
+                kobject_put(hstate_kobjs[h - hstates]);
+        }
+
+        kobject_put(hugepages_kobj);
+}
+module_exit(hugetlb_exit);
+
+static int __init hugetlb_init(void)
+{
+        BUILD_BUG_ON(HPAGE_SHIFT == 0);
+
+        if (!size_to_hstate(HPAGE_SIZE)) {
+                hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
+                parsed_hstate->max_huge_pages = default_hstate_max_huge_pages;
+        }
+        default_hstate_idx = size_to_hstate(HPAGE_SIZE) - hstates;
+
+        hugetlb_init_hstates();
+
+        report_hugepages();
+
+        hugetlb_sysfs_init();
+
+        return 0;
+}
+module_init(hugetlb_init);
+
+/* Should be called on processing a hugepagesz=... option */
+void __init hugetlb_add_hstate(unsigned order)
+{
+        struct hstate *h;
+        if (size_to_hstate(PAGE_SIZE << order)) {
+                printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
+                return;
+        }
+        BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
+        BUG_ON(order == 0);
+        h = &hstates[max_hstate++];
+        h->order = order;
+        h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
+        snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
+                                        huge_page_size(h)/1024);
+        hugetlb_init_one_hstate(h);
+        parsed_hstate = h;
+}
+
+static int __init hugetlb_setup(char *s)
+{
+        unsigned long *mhp;
+
+        /*
+         * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
+         * so this hugepages= parameter goes to the "default hstate".
+         */
+        if (!max_hstate)
+                mhp = &default_hstate_max_huge_pages;
+        else
+                mhp = &parsed_hstate->max_huge_pages;
+
+        if (sscanf(s, "%lu", mhp) <= 0)
+                *mhp = 0;
+
+        return 1;
+}
+__setup("hugepages=", hugetlb_setup);
+
+static unsigned int cpuset_mems_nr(unsigned int *array)
+{
+        int node;
+        unsigned int nr = 0;
+
+        for_each_node_mask(node, cpuset_current_mems_allowed)
+                nr += array[node];
+
+        return nr;
+}
+
 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
                            struct file *file, void __user *buffer,
                            size_t *length, loff_t *ppos)