From:   Peter Xu <peterx@redhat.com>
To:     linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc:     Axel Rasmussen <axelrasmussen@google.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Hugh Dickins <hughd@google.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        Alistair Popple <apopple@nvidia.com>,
        Jerome Glisse <jglisse@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>, peterx@redhat.com,
        David Hildenbrand <david@redhat.com>,
        Andrea Arcangeli <aarcange@redhat.com>
Subject: [PATCH v6 03/23] mm: Check against orig_pte for finish_fault()
Date:   Mon, 15 Nov 2021 15:55:02 +0800
Message-Id: <20211115075522.73795-4-peterx@redhat.com>
In-Reply-To: <20211115075522.73795-1-peterx@redhat.com>
References: <20211115075522.73795-1-peterx@redhat.com>
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We used to check against none pte and in those cases orig_pte should always be
none pte anyway.

This change prepares us to be able to call do_fault() on !none ptes.  For
example, we should allow that to happen for pte marker so that we can restore
information out of the pte markers.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 mm/memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index 04662b010005..d5966d9e24c3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4052,7 +4052,7 @@ vm_fault_t finish_fault(struct vm_fault *vmf)
 				      vmf->address, &vmf->ptl);
 	ret = 0;
 	/* Re-check under ptl */
-	if (likely(pte_none(*vmf->pte)))
+	if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
 		do_set_pte(vmf, page, vmf->address);
 	else
 		ret = VM_FAULT_NOPAGE;
-- 
2.32.0