Messages in this thread Patch in this message | | | From | Minchan Kim <> | Subject | [RFC 2/6] mm: keep dirty bit on anonymous page migration | Date | Wed, 3 Jun 2015 15:15:41 +0900 |
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Currently, If VM migrates anonymous page, we lose dirty bit of page table entry. Instead, VM translates dirty bit of page table as PG_dirty of page flags. It was okay because dirty bit of page table for anonymous page was no matter to swap out. Instead, VM took care of PG_dirty.
However, with introducing MADV_FREE, it's important to keep page table's dirty bit because It could make MADV_FREE handling logics more straighforward without taking care of PG_dirty.
This patch aims for preparing to remove PG_dirty check for MADV_FREE.
Signed-off-by: Minchan Kim <minchan@kernel.org> --- mm/migrate.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/mm/migrate.c b/mm/migrate.c index 236ee25e79d9..add30c3aaaa9 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -151,6 +151,10 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, if (is_write_migration_entry(entry)) pte = maybe_mkwrite(pte, vma); + /* MADV_FREE relies on pte_dirty. */ + if (PageAnon(new)) + pte = pte_mkdirty(pte); + #ifdef CONFIG_HUGETLB_PAGE if (PageHuge(new)) { pte = pte_mkhuge(pte); -- 1.9.1
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