From c1ef8e2c0235bffe4b0505c3325bb8a6af954021 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 12 Dec 2016 16:43:12 -0800 Subject: [PATCH] mm: disable numa migration faults for dax vmas Mark dax vmas as not migratable to exclude them from task_numa_work(). This is especially relevant for device-dax which wants to ensure predictable access latency and not incur periodic faults. [akpm@linux-foundation.org: add comment] Link: http://lkml.kernel.org/r/147892450132.22062.16875659431109209179.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reported-by: Aneesh Kumar K.V Cc: Michal Hocko Cc: Vlastimil Babka Cc: "Kirill A. Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mempolicy.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h index 5e5b2969d931..5f4d8281832b 100644 --- a/include/linux/mempolicy.h +++ b/include/linux/mempolicy.h @@ -7,6 +7,7 @@ #include +#include #include #include #include @@ -177,6 +178,13 @@ static inline bool vma_migratable(struct vm_area_struct *vma) if (vma->vm_flags & (VM_IO | VM_PFNMAP)) return false; + /* + * DAX device mappings require predictable access latency, so avoid + * incurring periodic faults. + */ + if (vma_is_dax(vma)) + return false; + #ifndef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION if (vma->vm_flags & VM_HUGETLB) return false; -- 2.30.2