gup_fast will skip over non present ptes (pte_numa requires the pte to be non present). So no explicit check is needed for pte_numa in the pte case. gup_fast will also automatically skip over THP when the trans huge pmd is non present (pmd_numa requires the pmd to be non present). But for the special pmd mode scan of knuma_scand (/sys/kernel/mm/autonuma/knuma_scand/pmd == 1), the pmd may be of numa type (so non present too), the pte may be present. gup_pte_range wouldn't notice the pmd is of numa type. So to avoid losing a NUMA hinting page fault with gup_fast we need an explicit check for pmd_numa() here to be sure it will fault through gup -> handle_mm_fault. Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> --- arch/x86/mm/gup.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index dd74e46..bf36575 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -164,7 +164,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, * wait_split_huge_page() would never return as the * tlb flush IPI wouldn't run. */ - if (pmd_none(pmd) || pmd_trans_splitting(pmd)) + if (pmd_none(pmd) || pmd_trans_splitting(pmd) || pmd_numa(pmd)) return 0; if (unlikely(pmd_large(pmd))) { if (!gup_huge_pmd(pmd, addr, next, write, pages, nr)) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>