Currently, khugepaged does not let swapin, if there is no enough young pages in a THP. The problem is when a THP does not have enough young page, khugepaged leaks mapped ptes.
This patch prohibits leaking mapped ptes. Signed-off-by: Ebru Akagunduz <[email protected]> Suggested-by: Andrea Arcangeli <[email protected]> --- mm/khugepaged.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 79c52d0..f401e9d 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -881,6 +881,11 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, .pmd = pmd, }; + /* we only decide to swapin, if there is enough young ptes */ + if (referenced < HPAGE_PMD_NR/2) { + trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); + return false; + } fe.pte = pte_offset_map(pmd, address); for (; fe.address < address + HPAGE_PMD_NR*PAGE_SIZE; fe.pte++, fe.address += PAGE_SIZE) { @@ -888,11 +893,6 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, if (!is_swap_pte(pteval)) continue; swapped_in++; - /* we only decide to swapin, if there is enough young ptes */ - if (referenced < HPAGE_PMD_NR/2) { - trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); - return false; - } ret = do_swap_page(&fe, pteval); /* do_swap_page returns VM_FAULT_RETRY with released mmap_sem */ -- 1.9.1
