mm/dynamic_hugetlb: use pfn to traverse subpages

hulk inclusion
category: bugfix
bugzilla: 46904 https://gitee.com/openeuler/kernel/issues/I4Y0XO

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

For 1G huge pages, the struct page of each subpages may be discontinuous, but
pfn must be continuous, so it's better to traverse subpages using pfn rathan
than struct page.
Signed-off-by: NLiu Shixin <liushixin2@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

mm/dynamic_hugetlb.c

@@ -54,20 +54,21 @@ static void __hpool_split_gigantic_page(struct dhugetlb_pool *hpool, struct page
 {
 	int nr_pages = 1 << (PUD_SHIFT - PAGE_SHIFT);
 	int nr_blocks = 1 << (PMD_SHIFT - PAGE_SHIFT);
-	int i;
+	int i, pfn = page_to_pfn(page);
 
 	lockdep_assert_held(&hpool->lock);
 	atomic_set(compound_mapcount_ptr(page), 0);
 	atomic_set(compound_pincount_ptr(page), 0);
 
 	for (i = 1; i < nr_pages; i++)
-		clear_compound_head(&page[i]);
+		clear_compound_head(pfn_to_page(pfn + i));
 	set_compound_order(page, 0);
 	page[1].compound_nr = 0;
 	__ClearPageHead(page);
 
 	for (i = 0; i < nr_pages; i+= nr_blocks)
-		add_new_page_to_pool(hpool, &page[i], HUGE_PAGES_POOL_2M);
+		add_new_page_to_pool(hpool, pfn_to_page(pfn + i),
+				     HUGE_PAGES_POOL_2M);
 }
 
 static void __hpool_split_huge_page(struct dhugetlb_pool *hpool, struct page *page)
@@ -208,7 +209,7 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo
 	struct huge_pages_pool *hpages_pool, *src_hpages_pool;
 	struct split_hugepage *split_page, *split_next;
 	unsigned long nr_pages, block_size;
-	struct page *page, *next;
+	struct page *page, *next, *p;
 	bool need_migrate = false;
 	int i, try;
 	LIST_HEAD(wait_page_list);
@@ -242,7 +243,8 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo
 		clear_percpu_pools(hpool);
 		page = pfn_to_page(split_page->start_pfn);
 		for (i = 0; i < nr_pages; i+= block_size) {
-			if (PagePool(&page[i])) {
+			p = pfn_to_page(split_page->start_pfn + i);
+			if (PagePool(p)) {
 				if (!need_migrate)
 					goto next;
 				else
@@ -252,11 +254,12 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo
 
 		list_del(&split_page->head_pages);
 		hpages_pool->split_normal_pages--;
-		kfree(split_page);
 		for (i = 0; i < nr_pages; i+= block_size) {
-			list_del(&page[i].lru);
+			p = pfn_to_page(split_page->start_pfn + i);
+			list_del(&p->lru);
 			src_hpages_pool->free_normal_pages--;
 		}
+		kfree(split_page);
 		add_new_page_to_pool(hpool, page, hpages_pool_idx);
 		trace_dynamic_hugetlb_split_merge(hpool, page, DHUGETLB_MERGE, page_size(page));
 		return 0;
@@ -269,8 +272,9 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo
 		/* Isolate free page first. */
 		INIT_LIST_HEAD(&wait_page_list);
 		for (i = 0; i < nr_pages; i+= block_size) {
-			if (!PagePool(&page[i])) {
-				list_move(&page[i].lru, &wait_page_list);
+			p = pfn_to_page(split_page->start_pfn + i);
+			if (!PagePool(p)) {
+				list_move(&p->lru, &wait_page_list);
 				src_hpages_pool->free_normal_pages--;
 			}
 		}
@@ -278,12 +282,13 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo
 		/* Unlock and try migration. */
 		spin_unlock(&hpool->lock);
 		for (i = 0; i < nr_pages; i+= block_size) {
-			if (PagePool(&page[i]))
+			p = pfn_to_page(split_page->start_pfn + i);
+			if (PagePool(p))
 				/*
 				 * TODO: fatal migration failures should bail
 				 * out
 				 */
-				do_migrate_range(page_to_pfn(&page[i]), page_to_pfn(&page[i]) + block_size);
+				do_migrate_range(page_to_pfn(p), page_to_pfn(p) + block_size);
 		}
 		spin_lock(&hpool->lock);
 
@@ -756,6 +761,9 @@ static int free_hugepage_to_hugetlb(struct dhugetlb_pool *hpool)
 	unsigned int nr_pages;
 	int nid, ret = 0;
 
+	if (!h)
+		return ret;
+
 	spin_lock(&hpool->lock);
 	spin_lock(&hugetlb_lock);
 	list_for_each_entry_safe(page, next, &hpages_pool->hugepage_freelists, lru) {
@@ -1028,7 +1036,7 @@ int hugetlb_pool_info_show(struct seq_file *m, void *v)
 		return 0;
 
 	if (!hpool) {
-		seq_printf(m, "Curent hierarchial have not memory pool.\n");
+		seq_printf(m, "Current hierarchial have not memory pool.\n");
 		return 0;
 	}