mm/dynamic_hugetlb: add interface to disable normal pages allocation

hulk inclusion
category: feature
bugzilla: 46904, https://gitee.com/openeuler/kernel/issues/I4QSHG
CVE: NA

--------------------------------

Add new interface "dhugetlb.disable_normal_pages" to disable the allocation
of normal pages from a hpool. This makes dynamic hugetlb more flexible.
Signed-off-by: NLiu Shixin <liushixin2@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

include/linux/dynamic_hugetlb.h

@@ -81,6 +81,8 @@ ssize_t write_2M_reserved_pages(struct kernfs_open_file *of,
 				char *buf, size_t nbytes, loff_t off);
 ssize_t write_1G_reserved_pages(struct kernfs_open_file *of,
 				char *buf, size_t nbytes, loff_t off);
+int normal_pages_disabled_write(struct cgroup_subsys_state *css, struct cftype *cft, u64 val);
+u64 normal_pages_disabled_read(struct cgroup_subsys_state *css, struct cftype *cft);
 ssize_t write_hugepage_to_hpool(struct kernfs_open_file *of,
 				char *buf, size_t nbytes, loff_t off);
 int hugetlb_pool_info_show(struct seq_file *m, void *v);

mm/dynamic_hugetlb.c

@@ -449,6 +449,8 @@ static struct page *__alloc_page_from_dhugetlb_pool(void)
 	if (!get_hpool_unless_zero(hpool))
 		return NULL;
 
+	if (hpool->normal_pages_disabled)
+		goto out;
 	percpu_pool = &hpool->percpu_pool[smp_processor_id()];
 	/*
 	 * Before we lock percpu_pool, must be sure hpool is unlocked.
@@ -474,6 +476,7 @@ static struct page *__alloc_page_from_dhugetlb_pool(void)
 
 unlock:
 	spin_unlock_irqrestore(&percpu_pool->lock, flags);
+out:
 	put_hpool(hpool);
 	return page;
 }
@@ -810,6 +813,33 @@ ssize_t write_1G_reserved_pages(struct kernfs_open_file *of,
 	return update_reserved_pages(memcg, buf, HUGE_PAGES_POOL_1G) ?: nbytes;
 }
 
+int normal_pages_disabled_write(struct cgroup_subsys_state *css,
+			       struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct dhugetlb_pool *hpool = memcg->hpool;
+
+	if (!dhugetlb_enabled || !hpool)
+		return -EINVAL;
+	if (!((val == 0) || (val == 1)))
+		return -EINVAL;
+
+	hpool->normal_pages_disabled = val;
+	return 0;
+}
+
+u64 normal_pages_disabled_read(struct cgroup_subsys_state *css,
+			      struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct dhugetlb_pool *hpool = memcg->hpool;
+
+	if (!dhugetlb_enabled || !hpool)
+		return 0;
+
+	return hpool->normal_pages_disabled;
+}
+
 ssize_t write_hugepage_to_hpool(struct kernfs_open_file *of,
 				char *buf, size_t nbytes, loff_t off)
 {

mm/memcontrol.c

@@ -5212,6 +5212,12 @@ static struct cftype mem_cgroup_legacy_files[] = {
 		.write = write_2M_reserved_pages,
 		.flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE | CFTYPE_NOT_ON_ROOT,
 	},
+	{
+		.name = "dhugetlb.disable_normal_pages",
+		.read_u64 = normal_pages_disabled_read,
+		.write_u64 = normal_pages_disabled_write,
+		.flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE | CFTYPE_NOT_ON_ROOT,
+	},
 #endif
 #ifdef CONFIG_NUMA
 	{