Commit a00c8f70 authored by Liu Shixin's avatar Liu Shixin Committed by openeuler-sync-bot
Browse files

mm/dynamic_hugetlb: add cond_resched() in hpool_merge_page() 

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


CVE: NA

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

hpool_merge_page() will traver hugepage_splitlists and try to merge pages.
The number of pages may be large and it will try to migrate pages which
are in used. So the process can take a long times. To avoid softlockup,
add cond_resched() before loop and migration.

Fixes: cdbeee51 ("mm/dynamic_hugetlb: add migration function")
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
(cherry picked from commit 55a2e4ab)
parent d4f56462

mm/dynamic_hugetlb.c

+7 −2
Original line number Diff line number Diff line
@@ -272,18 +272,21 @@ static int hpool_merge_page(struct dhugetlb_pool *hpool, int hpages_pool_idx, bo 
merge:

		can_merge = true;



		spin_unlock(&hpool->lock);

		cond_resched();

		/*

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

		 * lock of percpu pool sequentially and clear percpu pool.

		 */

		if (hpages_pool_idx == HUGE_PAGES_POOL_2M) {

			spin_unlock(&hpool->lock);

			dhugetlb_lock_all(hpool);

			for (i = 0; i < NR_PERCPU_POOL; i++) {

				percpu_pool = &hpool->percpu_pool[i];

				reclaim_pages_from_percpu_pool(hpool, percpu_pool,

							       percpu_pool->free_pages);

			}

		} else {

			spin_lock(&hpool->lock);

		}



		page = pfn_to_page(split_page->start_pfn);
@@ -360,13 +363,15 @@ 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 (PagePool(p)) {

				cond_resched();

				/*

				 * TODO: fatal migration failures should bail

				 * out

				 */

				do_migrate_range(page_to_pfn(p), page_to_pfn(p) + block_size);

			}

		}

		spin_lock(&hpool->lock);



		/*