Splitting THP PMD is simple: just unmap it as in DAX case.
Unlike DAX, we also remove the page from rmap and drop reference.
Signed-off-by: Kirill A. Shutemov <redacted>
---
mm/huge_memory.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 15704484abf4..985041c453bf 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2900,10 +2900,16 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
count_vm_event(THP_SPLIT_PMD);
- if (vma_is_dax(vma)) {
- pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+ if (!vma_is_anonymous(vma)) {
+ _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
if (is_huge_zero_pmd(_pmd))
put_huge_zero_page();
+ if (vma_is_dax(vma))
+ return;
+ page = pmd_page(_pmd);
+ page_remove_rmap(page, true);
+ put_page(page);
+ add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
return;
} else if (is_huge_zero_pmd(*pmd)) {
return __split_huge_zero_page_pmd(vma, haddr, pmd);--
2.7.0
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