linux-ext4 - [PATCH v1 03/14] mm: add iomem vma selection for memory migration

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Date:   Tue, 24 Aug 2021 22:48:17 -0500
From:   Alex Sierra <alex.sierra@....com>
To:     akpm@...ux-foundation.org, Felix.Kuehling@....com,
        linux-mm@...ck.org, rcampbell@...dia.com,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        hch@....de, jgg@...dia.com, jglisse@...hat.com
Subject: [PATCH v1 03/14] mm: add iomem vma selection for memory migration

In this case, this is used to migrate pages from device memory, back to
system memory. This particular device memory type should be accessible
by the CPU, through IOMEM access. Typically, zone device public type
memory falls into this category.

Signed-off-by: Alex Sierra <alex.sierra@....com>
---
 include/linux/migrate.h | 1 +
 mm/migrate.c            | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 4bb4e519e3f5..6b16f417384f 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -156,6 +156,7 @@ static inline unsigned long migrate_pfn(unsigned long pfn)
 enum migrate_vma_direction {
 	MIGRATE_VMA_SELECT_SYSTEM = 1 << 0,
 	MIGRATE_VMA_SELECT_DEVICE_PRIVATE = 1 << 1,
+	MIGRATE_VMA_SELECT_IOMEM = 1 << 2,
 };
 
 struct migrate_vma {
diff --git a/mm/migrate.c b/mm/migrate.c
index e3a10e2a1bb3..d4ae2da99607 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2406,7 +2406,8 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 			if (is_write_device_private_entry(entry))
 				mpfn |= MIGRATE_PFN_WRITE;
 		} else {
-			if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM))
+			if (!(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM) &&
+			    !(migrate->flags & MIGRATE_VMA_SELECT_IOMEM))
 				goto next;
 			pfn = pte_pfn(pte);
 			if (is_zero_pfn(pfn)) {
-- 
2.32.0