Transfer the soft_dirty from pmd to pte during THP splits.
This fix avoids losing the soft_dirty bit and avoids userland memory
corruption in the checkpoint.
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
---
mm/huge_memory.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b9570b5..cb95a83 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1512,7 +1512,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
struct page *page;
pgtable_t pgtable;
pmd_t _pmd;
- bool young, write, dirty;
+ bool young, write, dirty, soft_dirty;
unsigned long addr;
int i;
@@ -1546,6 +1546,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
write = pmd_write(*pmd);
young = pmd_young(*pmd);
dirty = pmd_dirty(*pmd);
+ soft_dirty = pmd_soft_dirty(*pmd);
pmdp_huge_split_prepare(vma, haddr, pmd);
pgtable = pgtable_trans_huge_withdraw(mm, pmd);
@@ -1562,6 +1563,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
swp_entry_t swp_entry;
swp_entry = make_migration_entry(page + i, write);
entry = swp_entry_to_pte(swp_entry);
+ if (soft_dirty)
+ entry = pte_swp_mksoft_dirty(entry);
} else {
entry = mk_pte(page + i, vma->vm_page_prot);
entry = maybe_mkwrite(entry, vma);
@@ -1569,6 +1572,8 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
entry = pte_wrprotect(entry);
if (!young)
entry = pte_mkold(entry);
+ if (soft_dirty)
+ entry = pte_mksoft_dirty(entry);
}
if (dirty)
SetPageDirty(page + i);
--
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