Unverified Commit 72228248 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!11702 userfaultfd: fix checks for huge PMDs 

Merge Pull Request from: @ci-robot 
 
PR sync from: Liu Shixin <liushixin2@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/K2F3PCNL6H3ZEZR36ARFQIQ67WZOCKOC/ 
 
https://gitee.com/src-openeuler/kernel/issues/IARWOX 
 
Link:https://gitee.com/openeuler/kernel/pulls/11702

 

Reviewed-by: default avatarYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: default avatarYang Yingliang <yangyingliang@huawei.com>
parents 37e1c472 4983e704

mm/userfaultfd.c

+12 −10
Original line number Diff line number Diff line
@@ -583,21 +583,23 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, 
		}



		dst_pmdval = pmd_read_atomic(dst_pmd);

		/*

		 * If the dst_pmd is mapped as THP don't

		 * override it and just be strict.

		 */

		if (unlikely(pmd_trans_huge(dst_pmdval))) {

			err = -EEXIST;

			break;

		}

		if (unlikely(pmd_none(dst_pmdval)) &&

		    unlikely(__pte_alloc(dst_mm, dst_pmd))) {

			err = -ENOMEM;

			break;

		}

		/* If an huge pmd materialized from under us fail */

		if (unlikely(pmd_trans_huge(*dst_pmd))) {

		dst_pmdval = pmd_read_atomic(dst_pmd);

		/*

		 * If the dst_pmd is THP don't override it and just be strict.

		 * (This includes the case where the PMD used to be THP and

		 * changed back to none after __pte_alloc().)

		 */

		if (unlikely(!pmd_present(dst_pmdval) || pmd_trans_huge(dst_pmdval) ||

			     pmd_devmap(dst_pmdval))) {

			err = -EEXIST;

			break;

		}

		if (unlikely(pmd_bad(dst_pmdval))) {

			err = -EFAULT;

			break;

		}