[PATCH 17/35] mm, dmemfs: support unmap_page_range() for dmemfs pmd

[yulei . kernel]

From: Yulei Zhang <yuleixzh...@tencent.com>

It is required by munmap() for dmemfs mapping.

Signed-off-by: Chen Zhuo <sagazc...@tencent.com>
Signed-off-by: Yulei Zhang <yuleixzh...@tencent.com>
---
 mm/huge_memory.c | 2 ++
 mm/memory.c      | 8 +++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 531493a0bc82..73af337b454e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1636,6 +1636,8 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct 
vm_area_struct *vma,
                spin_unlock(ptl);
                if (is_huge_zero_pmd(orig_pmd))
                        tlb_remove_page_size(tlb, pmd_page(orig_pmd), 
HPAGE_PMD_SIZE);
+       } else if (pmd_special(orig_pmd)) {
+               spin_unlock(ptl);
        } else if (is_huge_zero_pmd(orig_pmd)) {
                zap_deposited_table(tlb->mm, pmd);
                spin_unlock(ptl);
diff --git a/mm/memory.c b/mm/memory.c
index 469af373ae76..2d2c0f8a966b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1178,10 +1178,12 @@ static inline unsigned long zap_pmd_range(struct 
mmu_gather *tlb,
        pmd = pmd_offset(pud, addr);
        do {
                next = pmd_addr_end(addr, end);
-               if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 
pmd_devmap(*pmd)) {
-                       if (next - addr != HPAGE_PMD_SIZE)
+               if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
+                       pmd_devmap(*pmd) || pmd_special(*pmd)) {
+                       if (next - addr != HPAGE_PMD_SIZE) {
+                               VM_BUG_ON(pmd_special(*pmd));
                                __split_huge_pmd(vma, pmd, addr, false, NULL);
-                       else if (zap_huge_pmd(tlb, vma, pmd, addr))
+                       } else if (zap_huge_pmd(tlb, vma, pmd, addr))
                                goto next;
                        /* fall through */
                }
-- 
2.28.0