Commit 3a32dc14 authored by Liu Shixin's avatar Liu Shixin Committed by Zheng Zengkai
Browse files

mm/dynamic_hugetlb: check free_pages_prepares when split pages 

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



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

The hugepages may still remain PG_uptodate flags when freed. When splitting
hugepage to pages, the flag is not clear. This causes the page to be allocated
with PG_uptodate flags and user may read incorrect datas.

In order to solve this problem and similar problems, add free_pages_prepares()
to clear page when splitting pages to small pool.

Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 440bde99

mm/dynamic_hugetlb.c

+6 −4
Original line number Diff line number Diff line
@@ -74,14 +74,16 @@ static void __hpool_split_huge_page(struct dhugetlb_pool *hpool, struct page *pa 


	__ClearPageHead(page);

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

		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |

				1 << PG_referenced | 1 << PG_dirty |

				1 << PG_active | 1 << PG_private |

				1 << PG_writeback);

		if (i != 0) {

			page[i].mapping = NULL;

			clear_compound_head(&page[i]);

		}

		/*

		 * If a hugepage is mapped in private mode, the PG_uptodate bit

		 * will not be cleared when the hugepage freed. Clear the

		 * hugepage using free_pages_prepare() here.

		 */

		free_pages_prepare(&page[i], 0, false);

		add_new_page_to_pool(hpool, &page[i], HUGE_PAGES_POOL_4K);

	}

}