dhugetlb: skip dissolve hugepage belonging to dynamic hugetlb

hulk inclusion
category: feature
bugzilla: 46904, https://gitee.com/openeuler/kernel/issues/I6BDME
CVE: NA

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

The memory hotplug and memory failure will dissolve freed hugepages to
buddy system, this is not the expected behavior for dynamic hugetlb.
Skip the dissolve operation for hugepages belonging to dynamic hugetlb.
For memory hotplug, the hotplug operation is not allowed, if dhugetlb pool
existed. For memory failure, the hugepage will be discard directly.
Signed-off-by: NLiu Shixin <liushixin2@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

include/linux/hugetlb.h

@@ -751,6 +751,11 @@ static inline struct dhugetlb_pool *get_dhugetlb_pool_from_task(
 {
 	return NULL;
 }
+static inline struct dhugetlb_pool *get_dhugetlb_pool_from_dhugetlb_pagelist(
+							struct page *page)
+{
+	return NULL;
+}
 static inline void dhugetlb_pool_put(struct dhugetlb_pool *hpool) { return; }
 #endif /* CONFIG_DYNAMIC_HUGETLB */
 

mm/hugetlb.c

@@ -1769,12 +1769,20 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
 int dissolve_free_huge_page(struct page *page)
 {
 	int rc = -EBUSY;
+	struct dhugetlb_pool *hpool;
 
 retry:
 	/* Not to disrupt normal path by vainly holding hugetlb_lock */
 	if (!PageHuge(page))
 		return 0;
 
+	/* Skip dissolve hugepage for dynamic hugetlb */
+	hpool = get_dhugetlb_pool_from_dhugetlb_pagelist(page);
+	if (hpool) {
+		dhugetlb_pool_put(hpool);
+		return -EBUSY;
+	}
+
 	spin_lock(&hugetlb_lock);
 	if (!PageHuge(page)) {
 		rc = 0;
@@ -3426,8 +3434,12 @@ struct dhugetlb_pool *get_dhugetlb_pool_from_dhugetlb_pagelist(
 							struct page *page)
 {
 	struct dhugetlb_pool *hpool = NULL;
-	unsigned long idx = page_to_pfn(page) >> (PUD_SHIFT - PAGE_SHIFT);
+	unsigned long idx;
+
+	if (!dhugetlb_enabled)
+		return NULL;
 
+	idx = page_to_pfn(page) >> (PUD_SHIFT - PAGE_SHIFT);
 	read_lock(&dhugetlb_pagelist_rwlock);
 	if (idx < dhugetlb_pagelist_t->count)
 		hpool = dhugetlb_pagelist_t->hpool[idx];