From 0b9d705297b273657923518dbea2377cd03532ed Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Fri, 5 Oct 2012 21:36:27 +0200 Subject: mm: numa: Support NUMA hinting page faults from gup/gup_fast Introduce FOLL_NUMA to tell follow_page to check pte/pmd_numa. get_user_pages must use FOLL_NUMA, and it's safe to do so because it always invokes handle_mm_fault and retries the follow_page later. KVM secondary MMU page faults will trigger the NUMA hinting page faults through gup_fast -> get_user_pages -> follow_page -> handle_mm_fault. Other follow_page callers like KSM should not use FOLL_NUMA, or they would fail to get the pages if they use follow_page instead of get_user_pages. [ This patch was picked up from the AutoNUMA tree. ] Originally-by: Andrea Arcangeli Cc: Linus Torvalds Cc: Andrew Morton Cc: Peter Zijlstra Cc: Andrea Arcangeli Cc: Rik van Riel [ ported to this tree. ] Signed-off-by: Ingo Molnar Reviewed-by: Rik van Riel --- mm/memory.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index 7cf762857baa..cd8e0daf1912 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1517,6 +1517,8 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); goto out; } + if ((flags & FOLL_NUMA) && pmd_numa(*pmd)) + goto no_page_table; if (pmd_trans_huge(*pmd)) { if (flags & FOLL_SPLIT) { split_huge_page_pmd(mm, pmd); @@ -1546,6 +1548,8 @@ split_fallthrough: pte = *ptep; if (!pte_present(pte)) goto no_page; + if ((flags & FOLL_NUMA) && pte_numa(pte)) + goto no_page; if ((flags & FOLL_WRITE) && !pte_write(pte)) goto unlock; @@ -1697,6 +1701,19 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); vm_flags &= (gup_flags & FOLL_FORCE) ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); + + /* + * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault + * would be called on PROT_NONE ranges. We must never invoke + * handle_mm_fault on PROT_NONE ranges or the NUMA hinting + * page faults would unprotect the PROT_NONE ranges if + * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd + * bitflag. So to avoid that, don't set FOLL_NUMA if + * FOLL_FORCE is set. + */ + if (!(gup_flags & FOLL_FORCE)) + gup_flags |= FOLL_NUMA; + i = 0; do { -- cgit v1.2.3