Unverified Commit 3a0ee774 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!14330 mm/khugepaged: fix ->anon_vma race 

Merge Pull Request from: @ci-robot 
 
PR sync from: Jinjiang Tu <tujinjiang@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/J2LLKBOK2MMY2JIQOK5J5AY2U5HCMFD2/ 
 
https://gitee.com/openeuler/kernel/issues/IBE8BO 
 
Link:https://gitee.com/openeuler/kernel/pulls/14330

 

Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: default avatarLi Nan <linan122@huawei.com>
Signed-off-by: default avatarLi Nan <linan122@huawei.com>
parents 7e7ec9c2 cdf360a7

mm/khugepaged.c

+13 −1
Original line number Diff line number Diff line
@@ -1623,7 +1623,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) 
		 * has higher cost too. It would also probably require locking

		 * the anon_vma.

		 */

		if (vma->anon_vma)

		if (READ_ONCE(vma->anon_vma))

			continue;

		addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);

		if (addr & ~HPAGE_PMD_MASK)
@@ -1642,6 +1642,18 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) 
		 * reverse order. Trylock is a way to avoid deadlock.

		 */

		if (mmap_write_trylock(mm)) {

			/*

			 * Re-check whether we have an ->anon_vma, because

			 * collapse_and_free_pmd() requires that either no

			 * ->anon_vma exists or the anon_vma is locked.

			 * We already checked ->anon_vma above, but that check

			 * is racy because ->anon_vma can be populated under the

			 * mmap lock in read mode.

			 */

			if (vma->anon_vma) {

				mmap_write_unlock(mm);

				continue;

			}

			if (!khugepaged_test_exit(mm)) {

				struct mmu_notifier_range range;