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Subject[HMM v13 14/18] mm/hmm/migrate: support un-addressable ZONE_DEVICE page in migration
Date
Allow to unmap and restore special swap entry of un-addressable
ZONE_DEVICE memory.

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
---
mm/migrate.c | 11 ++++++++++-
mm/rmap.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 66ce6b4..6b6b457 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -40,6 +40,7 @@
#include <linux/mmu_notifier.h>
#include <linux/page_idle.h>
#include <linux/page_owner.h>
+#include <linux/memremap.h>

#include <asm/tlbflush.h>

@@ -248,7 +249,15 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
pte = arch_make_huge_pte(pte, vma, new, 0);
}
#endif
- flush_dcache_page(new);
+
+ if (unlikely(is_zone_device_page(new)) && !is_addressable_page(new)) {
+ entry = make_device_entry(new, pte_write(pte));
+ pte = swp_entry_to_pte(entry);
+ if (pte_swp_soft_dirty(*ptep))
+ pte = pte_mksoft_dirty(pte);
+ } else
+ flush_dcache_page(new);
+
set_pte_at(mm, addr, ptep, pte);

if (PageHuge(new)) {
diff --git a/mm/rmap.c b/mm/rmap.c
index 1ef3640..fff3578 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -61,6 +61,7 @@
#include <linux/hugetlb.h>
#include <linux/backing-dev.h>
#include <linux/page_idle.h>
+#include <linux/memremap.h>

#include <asm/tlbflush.h>

@@ -1455,6 +1456,52 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
goto out;
}

+ if ((flags & TTU_MIGRATION) && is_zone_device_page(page)) {
+ swp_entry_t entry;
+ pte_t swp_pte;
+ pmd_t *pmdp;
+
+ if (!(page->pgmap->flags & MEMORY_MOVABLE))
+ goto out;
+
+ pmdp = mm_find_pmd(mm, address);
+ if (!pmdp)
+ goto out;
+
+ pte = pte_offset_map_lock(mm, pmdp, address, &ptl);
+ if (!pte)
+ goto out;
+
+ pteval = ptep_get_and_clear(mm, address, pte);
+ if (pte_present(pteval) || pte_none(pteval)) {
+ set_pte_at(mm, address, pte, pteval);
+ goto out_unmap;
+ }
+
+ entry = pte_to_swp_entry(pteval);
+ if (!is_device_entry(entry)) {
+ set_pte_at(mm, address, pte, pteval);
+ goto out_unmap;
+ }
+
+ if (device_entry_to_page(entry) != page) {
+ set_pte_at(mm, address, pte, pteval);
+ goto out_unmap;
+ }
+
+ /*
+ * Store the pfn of the page in a special migration
+ * pte. do_swap_page() will wait until the migration
+ * pte is removed and then restart fault handling.
+ */
+ entry = make_migration_entry(page, 0);
+ swp_pte = swp_entry_to_pte(entry);
+ if (pte_soft_dirty(*pte))
+ swp_pte = pte_swp_mksoft_dirty(swp_pte);
+ set_pte_at(mm, address, pte, swp_pte);
+ goto discard;
+ }
+
pte = page_check_address(page, mm, address, &ptl,
PageTransCompound(page));
if (!pte)
--
2.4.3
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