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From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Rik van Riel <riel@surriel.com>,
	Muchun Song <songmuchun@bytedance.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	peterx@redhat.com, James Houghton <jthoughton@google.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	David Hildenbrand <david@redhat.com>,
	Miaohe Lin <linmiaohe@huawei.com>,
	Mike Kravetz <mike.kravetz@oracle.com>
Subject: [PATCH RFC v2 09/12] mm/hugetlb: Use hugetlb walker lock in hugetlb_vma_maps_page()
Date: Thu, 17 Nov 2022 20:10:22 -0500	[thread overview]
Message-ID: <20221118011025.2178986-10-peterx@redhat.com> (raw)
In-Reply-To: <20221118011025.2178986-1-peterx@redhat.com>

Hugetlb walker lock makes sure the pte_t* won't go away from under us.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 fs/hugetlbfs/inode.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index fdb16246f46e..265508981ba1 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -387,21 +387,24 @@ static bool hugetlb_vma_maps_page(struct vm_area_struct *vma,
 				unsigned long addr, struct page *page)
 {
 	pte_t *ptep, pte;
+	bool result = false;
 
+	hugetlb_walker_lock();
 	ptep = huge_pte_offset(vma->vm_mm, addr,
 			huge_page_size(hstate_vma(vma)));
 
 	if (!ptep)
-		return false;
+		goto out;
 
 	pte = huge_ptep_get(ptep);
 	if (huge_pte_none(pte) || !pte_present(pte))
-		return false;
+		goto out;
 
 	if (pte_page(pte) == page)
-		return true;
-
-	return false;
+		result = true;
+out:
+	hugetlb_walker_unlock();
+	return result;
 }
 
 /*
-- 
2.37.3


  parent reply	other threads:[~2022-11-18  1:13 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-18  1:10 [PATCH RFC v2 00/12] mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare Peter Xu
2022-11-18  1:10 ` [PATCH RFC v2 01/12] mm/hugetlb: Let vma_offset_start() to return start Peter Xu
2022-11-18  1:10 ` [PATCH RFC v2 02/12] mm/hugetlb: Move swap entry handling into vma lock for fault Peter Xu
2022-11-18  1:35   ` Peter Xu
2022-11-18  1:10 ` [PATCH RFC v2 03/12] mm/hugetlb: Don't wait for migration entry during follow page Peter Xu
2022-11-18  1:10 ` [PATCH RFC v2 04/12] mm/hugetlb: Add pgtable walker lock Peter Xu
2022-11-18  1:10 ` [PATCH RFC v2 05/12] mm/hugetlb: Make userfaultfd_huge_must_wait() safe to pmd unshare Peter Xu
2022-11-18  1:10 ` [PATCH RFC v2 06/12] mm/hugetlb: Protect huge_pmd_share() with walker lock Peter Xu
2022-11-18  1:17   ` Peter Xu
2022-11-18  1:10 ` [PATCH RFC v2 07/12] mm/hugetlb: Use hugetlb walker lock in hugetlb_follow_page_mask() Peter Xu
2022-11-18  1:10 ` [PATCH RFC v2 08/12] mm/hugetlb: Use hugetlb walker lock in follow_hugetlb_page() Peter Xu
2022-11-18  1:10 ` Peter Xu [this message]
2022-11-18  1:10 ` [PATCH RFC v2 10/12] mm/hugetlb: Use hugetlb walker lock in walk_hugetlb_range() Peter Xu
2022-11-18  1:11 ` [PATCH RFC v2 11/12] mm/hugetlb: Use hugetlb walker lock in page_vma_mapped_walk() Peter Xu
2022-11-18  1:11 ` [PATCH RFC v2 12/12] mm/hugetlb: Introduce hugetlb_walk() Peter Xu
2022-11-23  9:40 ` [PATCH RFC v2 00/12] mm/hugetlb: Make huge_pte_offset() thread-safe for pmd unshare David Hildenbrand
2022-11-23 15:09   ` Peter Xu
2022-11-23 18:21     ` Mike Kravetz
2022-11-23 18:56       ` Peter Xu
2022-11-23 19:31         ` David Hildenbrand
2022-11-25  9:43     ` David Hildenbrand
2022-11-25 13:55       ` Peter Xu

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