The only user of devmap PTEs is FS DAX, and khugepaged should not be scanning these VMAs. This is checked by calling hugepage_vma_check. Therefore khugepaged should never encounter a devmap PTE. Warn if this occurs. Signed-off-by: Alistair Popple <apopple@xxxxxxxxxx> --- Note this is a transitory patch to test the above assumption both at runtime and during review. I will likely remove it as the whole thing gets deleted when pXX_devmap is removed. --- mm/khugepaged.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 88433cc..b10db15 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -955,7 +955,7 @@ static int find_pmd_or_thp_or_none(struct mm_struct *mm, return SCAN_PMD_NULL; if (pmd_trans_huge(pmde)) return SCAN_PMD_MAPPED; - if (pmd_devmap(pmde)) + if (WARN_ON_ONCE(pmd_devmap(pmde))) return SCAN_PMD_NULL; if (pmd_bad(pmde)) return SCAN_PMD_NULL; -- git-series 0.9.1
