dhugetlb: set hpool to NULL for cont-bit hugepage

hulk inclusion
category: bugfix
bugzilla: 46904, https://gitee.com/openeuler/kernel/issues/I6FCQZ
CVE: NA

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

When dynamic hugetlb is enabled, the hpool should be NULL for cont-bit
hugepage, set it.

Fixes: f15774c6 ("dhugetlb: only support 1G/2M hugepage and ARM64_4K_PAGES")
Signed-off-by: NLiu Shixin <liushixin2@huawei.com>
Reviewed-by: NNanyong Sun <sunnanyong@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

fs/hugetlbfs/inode.c

@@ -1183,6 +1183,8 @@ static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
 	if (huge_page_size(sbinfo->hstate) == PMD_SIZE ||
 	    huge_page_size(sbinfo->hstate) == PUD_SIZE)
 		p->hpool = get_dhugetlb_pool_from_task(current);
+	else
+		p->hpool = NULL;
 #endif
 
 	return &p->vfs_inode;