From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 021436B02AE for ; Tue, 15 Nov 2016 13:50:18 -0500 (EST) Received: by mail-wm0-f71.google.com with SMTP id i131so6194782wmf.3 for ; Tue, 15 Nov 2016 10:50:17 -0800 (PST) Received: from newverein.lst.de (verein.lst.de. [213.95.11.211]) by mx.google.com with ESMTPS id pp3si29667002wjb.160.2016.11.15.10.50.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 Nov 2016 10:50:16 -0800 (PST) Date: Tue, 15 Nov 2016 19:50:15 +0100 From: Christoph Hellwig Subject: Re: [PATCH] mm: add ZONE_DEVICE statistics to smaps Message-ID: <20161115185015.GA5854@lst.de> References: <147881591739.39198.1358237993213024627.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: Christoph Hellwig , Dave Hansen , "linux-nvdimm@lists.01.org" , "linux-kernel@vger.kernel.org" , Linux MM , Andrew Morton Hi Dan, On Mon, Nov 14, 2016 at 07:14:22PM -0800, Dan Williams wrote: > Wanted to get your opinion on this given your earlier concerns about > the VM_DAX flag. > > This instead lets an application know how much of a vma is backed by > ZONE_DEVICE pages, but does not make any indications about the vma > having DAX semantics or not. I.e. it is possible that 'device' and > 'device_huge' are non-zero *and* vma_is_dax() is false. So, it is > purely accounting the composition of the present pages in the vma. > > Another option is to have something like 'shared_thp' just to account > for file backed huge pages that dax can map. However if ZONE_DEVICE > is leaking into other use cases I think it makes sense to have it be a > first class-citizen with respect to accounting alongside > 'anonymous_thp'. This counter sounds fine to me, it's a debug tool and not an obvious abuse candidate like VM_DAX. But I'll defer to the VM folks for a real review. -- 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