From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1426551AbdD1Rlk (ORCPT ); Fri, 28 Apr 2017 13:41:40 -0400 Received: from mail-io0-f173.google.com ([209.85.223.173]:35100 "EHLO mail-io0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1426525AbdD1RlX (ORCPT ); Fri, 28 Apr 2017 13:41:23 -0400 MIME-Version: 1.0 In-Reply-To: <1743017574.4309811.1493400875692.JavaMail.zimbra@redhat.com> References: <20170428063913.iz6xjcxblecofjlq@gmail.com> <149339998297.24933.1129582806028305912.stgit@dwillia2-desk3.amr.corp.intel.com> <1743017574.4309811.1493400875692.JavaMail.zimbra@redhat.com> From: Dan Williams Date: Fri, 28 Apr 2017 10:41:22 -0700 Message-ID: Subject: Re: [PATCH v2] mm, zone_device: replace {get, put}_zone_device_page() with a single reference To: Jerome Glisse Cc: Ingo Molnar , "linux-kernel@vger.kernel.org" , Linux MM , Ingo Molnar , Andrew Morton , Logan Gunthorpe , Kirill Shutemov Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 28, 2017 at 10:34 AM, Jerome Glisse wrote: >> Kirill points out that the calls to {get,put}_dev_pagemap() can be >> removed from the mm fast path if we take a single get_dev_pagemap() >> reference to signify that the page is alive and use the final put of the >> page to drop that reference. >> >> This does require some care to make sure that any waits for the >> percpu_ref to drop to zero occur *after* devm_memremap_page_release(), >> since it now maintains its own elevated reference. > > This is NAK from HMM point of view as i need those call. So if you remove > them now i will need to add them back as part of HMM. I thought you only need them at page free time? You can still hook __put_page(). From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f200.google.com (mail-io0-f200.google.com [209.85.223.200]) by kanga.kvack.org (Postfix) with ESMTP id 047D46B02F4 for ; Fri, 28 Apr 2017 13:41:24 -0400 (EDT) Received: by mail-io0-f200.google.com with SMTP id l11so33740096iod.15 for ; Fri, 28 Apr 2017 10:41:24 -0700 (PDT) Received: from mail-io0-x22a.google.com (mail-io0-x22a.google.com. [2607:f8b0:4001:c06::22a]) by mx.google.com with ESMTPS id t138si55461ita.48.2017.04.28.10.41.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 28 Apr 2017 10:41:23 -0700 (PDT) Received: by mail-io0-x22a.google.com with SMTP id r16so71576867ioi.2 for ; Fri, 28 Apr 2017 10:41:23 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1743017574.4309811.1493400875692.JavaMail.zimbra@redhat.com> References: <20170428063913.iz6xjcxblecofjlq@gmail.com> <149339998297.24933.1129582806028305912.stgit@dwillia2-desk3.amr.corp.intel.com> <1743017574.4309811.1493400875692.JavaMail.zimbra@redhat.com> From: Dan Williams Date: Fri, 28 Apr 2017 10:41:22 -0700 Message-ID: Subject: Re: [PATCH v2] mm, zone_device: replace {get, put}_zone_device_page() with a single reference Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Jerome Glisse Cc: Ingo Molnar , "linux-kernel@vger.kernel.org" , Linux MM , Ingo Molnar , Andrew Morton , Logan Gunthorpe , Kirill Shutemov On Fri, Apr 28, 2017 at 10:34 AM, Jerome Glisse wrote: >> Kirill points out that the calls to {get,put}_dev_pagemap() can be >> removed from the mm fast path if we take a single get_dev_pagemap() >> reference to signify that the page is alive and use the final put of the >> page to drop that reference. >> >> This does require some care to make sure that any waits for the >> percpu_ref to drop to zero occur *after* devm_memremap_page_release(), >> since it now maintains its own elevated reference. > > This is NAK from HMM point of view as i need those call. So if you remove > them now i will need to add them back as part of HMM. I thought you only need them at page free time? You can still hook __put_page(). -- 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