[PATCH 03/19] mm: Mark special bits for huge pfn mappings when inject

Peter Xu
2024-08-09T16:09:24Z

We need these special bits to be around to enable gup-fast on pfnmaps.
Mark properly for !devmap case, reflecting that there's no page struct
backing the entry.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
mm/huge_memory.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 39c401a62e87..e95b3a468aee 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1162,6 +1162,8 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
if (pfn_t_devmap(pfn))
entry = pmd_mkdevmap(entry);
+ else
+ entry = pmd_mkspecial(entry);
if (write) {
entry = pmd_mkyoung(pmd_mkdirty(entry));
entry = maybe_pmd_mkwrite(entry, vma);
@@ -1258,6 +1260,8 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
entry = pud_mkhuge(pfn_t_pud(pfn, prot));
if (pfn_t_devmap(pfn))
entry = pud_mkdevmap(entry);
+ else
+ entry = pud_mkspecial(entry);
if (write) {
entry = pud_mkyoung(pud_mkdirty(entry));
entry = maybe_pud_mkwrite(entry, vma);
--
2.45.0