From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f71.google.com (mail-pa0-f71.google.com [209.85.220.71]) by kanga.kvack.org (Postfix) with ESMTP id A58256B0038 for ; Mon, 14 Nov 2016 19:25:31 -0500 (EST) Received: by mail-pa0-f71.google.com with SMTP id rf5so101886929pab.3 for ; Mon, 14 Nov 2016 16:25:31 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id m24si24210350pfg.258.2016.11.14.16.25.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 14 Nov 2016 16:25:30 -0800 (PST) Date: Mon, 14 Nov 2016 16:25:29 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: disable numa migration faults for dax vmas Message-Id: <20161114162529.1a5b08ff90f6f199c1be8cc9@linux-foundation.org> In-Reply-To: <147892450132.22062.16875659431109209179.stgit@dwillia2-desk3.amr.corp.intel.com> References: <147892450132.22062.16875659431109209179.stgit@dwillia2-desk3.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: Michal Hocko , linux-nvdimm@ml01.01.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" , Vlastimil Babka , "Aneesh Kumar K.V" On Fri, 11 Nov 2016 20:21:41 -0800 Dan Williams wrote: > 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. > > ... > > @@ -177,6 +178,9 @@ static inline bool vma_migratable(struct vm_area_struct *vma) > if (vma->vm_flags & (VM_IO | VM_PFNMAP)) > return false; > > + if (vma_is_dax(vma)) > + return false; > + > #ifndef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION > if (vma->vm_flags & VM_HUGETLB) > return false; I don't think the reader could figure out why this code is here, so... this? --- a/include/linux/mempolicy.h~mm-disable-numa-migration-faults-for-dax-vmas-fix +++ a/include/linux/mempolicy.h @@ -180,6 +180,10 @@ static inline bool vma_migratable(struct 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; _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org