linux-kernel - [PATCH 5.4 082/141] mm/migrate.c: fix potential indeterminate pte entry in migrate_vma_insert

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Date:   Mon, 17 May 2021 16:02:14 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miaohe Lin <linmiaohe@...wei.com>,
        David Hildenbrand <david@...hat.com>,
        Alistair Popple <apopple@...dia.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Rafael Aquini <aquini@...hat.com>,
        Yang Shi <shy828301@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 082/141] mm/migrate.c: fix potential indeterminate pte entry in migrate_vma_insert_page()

From: Miaohe Lin <linmiaohe@...wei.com>

[ Upstream commit 34f5e9b9d1990d286199084efa752530ee3d8297 ]

If the zone device page does not belong to un-addressable device memory,
the variable entry will be uninitialized and lead to indeterminate pte
entry ultimately.  Fix this unexpected case and warn about it.

Link: https://lkml.kernel.org/r/20210325131524.48181-4-linmiaohe@huawei.com
Fixes: df6ad69838fc ("mm/device-public-memory: device memory cache coherent with CPU")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Reviewed-by: David Hildenbrand <david@...hat.com>
Cc: Alistair Popple <apopple@...dia.com>
Cc: Jerome Glisse <jglisse@...hat.com>
Cc: Rafael Aquini <aquini@...hat.com>
Cc: Yang Shi <shy828301@...il.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 mm/migrate.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/migrate.c b/mm/migrate.c
index c4c313e47f12..00bbe57c1ce2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2771,6 +2771,13 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
 
 			swp_entry = make_device_private_entry(page, vma->vm_flags & VM_WRITE);
 			entry = swp_entry_to_pte(swp_entry);
+		} else {
+			/*
+			 * For now we only support migrating to un-addressable
+			 * device memory.
+			 */
+			pr_warn_once("Unsupported ZONE_DEVICE page type.\n");
+			goto abort;
 		}
 	} else {
 		entry = mk_pte(page, vma->vm_page_prot);
-- 
2.30.2