Commit e7d25e74 authored by Liu Shixin's avatar Liu Shixin
Browse files

mm/dynamic_hugetlb: reduce the number of migration attempts 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I9K8D1


CVE: NA

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

do_migrate_range() will firstly isolate pages and then migrate pages. If
a pages is failed to isolate, it may not be successful in a short time
even if tried many times. Since migrate_pages() has already tried 10 times
to migrate the pages, there is also no need to migrate pages many times.

So just call do_migrate_range() once. This will reduce the log of migration
failures.

Fixes: cdbeee51 ("mm/dynamic_hugetlb: add migration function")
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
parent 154d1b25

mm/dynamic_hugetlb.c

+17 −16
Original line number Diff line number Diff line
@@ -231,9 +231,6 @@ static void reclaim_pages_from_percpu_pool(struct dhugetlb_pool *hpool, 
	}

}



/* We only try 5 times to reclaim pages */

#define	HPOOL_RECLAIM_RETRIES	5



static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bool force_merge)

{

	struct huge_pages_pool *hpages_pool, *src_hpages_pool;
@@ -242,7 +239,8 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo 
	struct page *page, *next, *p;

	struct percpu_pages_pool *percpu_pool;

	bool need_migrate = false, need_initial = false;

	int i, try;

	bool tried_migrate, can_merge;

	int i;

	LIST_HEAD(wait_page_list);



	lockdep_assert_held(&hpool->lock);
@@ -269,9 +267,11 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo 
		return -ENOMEM;



	list_for_each_entry_safe(split_page, split_next, &hpages_pool->hugepage_splitlists, head_pages) {

		try = 0;

		tried_migrate = false;



merge:

		can_merge = true;



		/*

		 * If we are merging 4K page to 2M page, we need to get

		 * lock of percpu pool sequentially and clear percpu pool.
@@ -290,8 +290,14 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo 
		for (i = 0; i < nr_pages; i+= block_size) {

			p = pfn_to_page(split_page->start_pfn + i);

			if (PagePool(p)) {

				if (!need_migrate)

					goto next;

				/*

				 * Some pages still in use, can't merge.

				 * If don't need migration or have tried,

				 * then skip merging these pages.

				 */

				can_merge = false;

				if (!need_migrate || tried_migrate)

					break;

				else

					goto migrate;

			}
@@ -303,6 +309,9 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo 
			 */

			dhugetlb_percpu_pool_unlock_all(hpool);



		if (!can_merge)

			continue;



		list_del(&split_page->head_pages);

		hpages_pool->split_normal_pages--;

		for (i = 0; i < nr_pages; i+= block_size) {
@@ -333,16 +342,8 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo 
		add_new_page_to_pool(hpool, page, hpages_pool_idx);

		trace_dynamic_hugetlb_split_merge(hpool, page, DHUGETLB_MERGE, page_size(page));

		return 0;

next:

		if (hpages_pool_idx == HUGE_PAGES_POOL_2M)

			/* Unlock percpu pool before try next */

			dhugetlb_percpu_pool_unlock_all(hpool);



		continue;

migrate:

		/* page migration only used for HUGE_PAGES_POOL_2M */

		if (try++ >= HPOOL_RECLAIM_RETRIES)

			goto next;

		tried_migrate = true;



		/* Isolate free page first. */

		INIT_LIST_HEAD(&wait_page_list);