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Subject[PATCH v7 4/6] mm: pvmw: add support for walking devmap pages
Date
The devmap pages can not use page_vma_mapped_walk() to check if a huge
devmap page is mapped into a vma. Add support for walking huge devmap
pages so that DAX can use it in the next patch.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
mm/page_vma_mapped.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 1187f9c1ec5b..3da82bf65de8 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -210,16 +210,10 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
*/
pmde = READ_ONCE(*pvmw->pmd);

- if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde)) {
+ if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde) ||
+ (pmd_present(pmde) && pmd_devmap(pmde))) {
pvmw->ptl = pmd_lock(mm, pvmw->pmd);
pmde = *pvmw->pmd;
- if (likely(pmd_trans_huge(pmde))) {
- if (pvmw->flags & PVMW_MIGRATION)
- return not_found(pvmw);
- if (!check_pmd(pmd_pfn(pmde), pvmw))
- return not_found(pvmw);
- return true;
- }
if (!pmd_present(pmde)) {
swp_entry_t entry;

@@ -232,6 +226,13 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
return not_found(pvmw);
return true;
}
+ if (likely(pmd_trans_huge(pmde) || pmd_devmap(pmde))) {
+ if (pvmw->flags & PVMW_MIGRATION)
+ return not_found(pvmw);
+ if (!check_pmd(pmd_pfn(pmde), pvmw))
+ return not_found(pvmw);
+ return true;
+ }
/* THP pmd was split under us: handle on pte level */
spin_unlock(pvmw->ptl);
pvmw->ptl = NULL;
--
2.11.0
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