[PATCH 07/35] autonuma: teach gup_fast about pte_numa

[Andrea Arcangeli]

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))
--
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