From a5430dda8a3a1cdd532e37270e6f36436241b6e7 Mon Sep 17 00:00:00 2001
From: Jérôme Glisse <jglisse@redhat.com>
Date: Fri, 8 Sep 2017 16:12:17 -0700
Subject: mm/migrate: support un-addressable ZONE_DEVICE page in migration
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Allow to unmap and restore special swap entry of un-addressable
ZONE_DEVICE memory.

Link: http://lkml.kernel.org/r/20170817000548.32038-17-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/page_vma_mapped.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'mm/page_vma_mapped.c')

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 3bd3008db4cb..6a03946469a9 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -48,6 +48,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw)
 		if (!is_swap_pte(*pvmw->pte))
 			return false;
 		entry = pte_to_swp_entry(*pvmw->pte);
+
 		if (!is_migration_entry(entry))
 			return false;
 		if (migration_entry_to_page(entry) - pvmw->page >=
@@ -60,6 +61,15 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw)
 		WARN_ON_ONCE(1);
 #endif
 	} else {
+		if (is_swap_pte(*pvmw->pte)) {
+			swp_entry_t entry;
+
+			entry = pte_to_swp_entry(*pvmw->pte);
+			if (is_device_private_entry(entry) &&
+			    device_private_entry_to_page(entry) == pvmw->page)
+				return true;
+		}
+
 		if (!pte_present(*pvmw->pte))
 			return false;
 
-- 
cgit