From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 2BE3C202E60EF for ; Fri, 20 Oct 2017 09:25:55 -0700 (PDT) Date: Fri, 20 Oct 2017 18:29:33 +0200 From: Christoph Hellwig Subject: Re: [PATCH v3 02/13] dax: require 'struct page' for filesystem dax Message-ID: <20171020162933.GA26320@lst.de> References: <150846713528.24336.4459262264611579791.stgit@dwillia2-desk3.amr.corp.intel.com> <150846714747.24336.14704246566580871364.stgit@dwillia2-desk3.amr.corp.intel.com> <20171020075735.GA14378@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Dan Williams Cc: Jan Kara , "linux-nvdimm@lists.01.org" , Benjamin Herrenschmidt , Heiko Carstens , "linux-kernel@vger.kernel.org" , linux-xfs@vger.kernel.org, Linux MM , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , linux-fsdevel , Andrew Morton , Christoph Hellwig , Gerald Schaefer List-ID: T24gRnJpLCBPY3QgMjAsIDIwMTcgYXQgMDg6MjM6MDJBTSAtMDcwMCwgRGFuIFdpbGxpYW1zIHdy b3RlOgo+IFllcywgaG93ZXZlciBpdCBzZWVtcyB0aGVzZSBkcml2ZXJzIC8gcGxhdGZvcm1zIGhh dmUgYmVlbiBsaXZpbmcgd2l0aAo+IHRoZSBsYWNrIG9mIHN0cnVjdCBwYWdlIGZvciBhIGxvbmcg dGltZS4gU28gdGhleSBlaXRoZXIgZG9uJ3QgdXNlIERBWCwKPiBvciB0aGV5IGhhdmUgYSBjb25z dHJhaW5lZCB1c2UgY2FzZSB0aGF0IG5ldmVyIHRyaWdnZXJzCj4gZ2V0X3VzZXJfcGFnZXMoKS4g SWYgaXQgaXMgdGhlIGxhdHRlciB0aGVuIHRoZXkgY291bGQgaW50cm9kdWNlIGEgbmV3Cj4gY29u ZmlndXJhdGlvbiBvcHRpb24gdGhhdCBieXBhc3NlcyB0aGUgcGZuX3RfZGV2bWFwKCkgY2hlY2sg aW4KPiBiZGV2X2RheF9zdXBwb3J0ZWQoKSBhbmQgZml4IHVwIHRoZSBnZXRfdXNlcl9wYWdlcygp IHBhdGhzIHRvIGZhaWwuCj4gU28sIEknZCBsaWtlIHRvIHVuZGVyc3RhbmQgaG93IHRoZXNlIGRy aXZlcnMgaGF2ZSBiZWVuIHVzaW5nIERBWAo+IHN1cHBvcnQgd2l0aG91dCBzdHJ1Y3QgcGFnZSB0 byBzZWUgaWYgd2UgbmVlZCBhIHdvcmthcm91bmQgb3Igd2UgY2FuCj4gZ28gYWhlYWQgZGVsZXRl IHRoaXMgc3VwcG9ydC4gSWYgdGhlIHVzYWdlIGlzIGxpbWl0ZWQgdG8KPiBleGVjdXRlLWluLXBs YWNlIHBlcmhhcHMgd2UgY2FuIGRvIGEgY29uc3RyYWluZWQgLT5kaXJlY3RfYWNjZXNzKCkgZm9y Cj4ganVzdCB0aGF0IGNhc2UuCgpGb3IgYXhvbnJhbSBJIGRvdWJ0IGFueW9uZSBpcyB1c2luZyBp dCBhbnkgbW9yZSAtIGl0IHdhcyBhIHZlcnkgZm9yCnRoZSBJQk0gQ2VsbCBibGFkZXMsIHdoaWNo IHdlcmUgcHJvZHVjZdGVIGluIGEgcmF0aGVyIGxpbWl0ZWQgbnVtYmVyLgpBbmQgQ2VsbCBiYXNp Y2FsbHkgc2VlbXMgdG8gYmUgZGVhZCBhcyBmYXIgYXMgSSBjYW4gdGVsbC4KCkZvciBTLzM5MCBN YXJ0aW4gbWlnaHQgYmUgYWJsZSB0byBoZWxwIG91dCB3aGF0IHRoZSBzdGF0dXMgb2YgeHByYW0K aW4gZ2VuZXJhbCBhbmQgREFYIHN1cHBvcnQgaW4gcGFydGljdWxhciBpcy4KX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KTGludXgtbnZkaW1tIG1haWxpbmcg bGlzdApMaW51eC1udmRpbW1AbGlzdHMuMDEub3JnCmh0dHBzOi8vbGlzdHMuMDEub3JnL21haWxt YW4vbGlzdGluZm8vbGludXgtbnZkaW1tCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753256AbdJTQ3h (ORCPT ); Fri, 20 Oct 2017 12:29:37 -0400 Received: from verein.lst.de ([213.95.11.211]:49750 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752934AbdJTQ3f (ORCPT ); Fri, 20 Oct 2017 12:29:35 -0400 Date: Fri, 20 Oct 2017 18:29:33 +0200 From: Christoph Hellwig To: Dan Williams Cc: Christoph Hellwig , Andrew Morton , Jan Kara , "linux-nvdimm@lists.01.org" , Benjamin Herrenschmidt , Heiko Carstens , "linux-kernel@vger.kernel.org" , linux-xfs@vger.kernel.org, Linux MM , Jeff Moyer , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , linux-fsdevel , Ross Zwisler , Gerald Schaefer Subject: Re: [PATCH v3 02/13] dax: require 'struct page' for filesystem dax Message-ID: <20171020162933.GA26320@lst.de> References: <150846713528.24336.4459262264611579791.stgit@dwillia2-desk3.amr.corp.intel.com> <150846714747.24336.14704246566580871364.stgit@dwillia2-desk3.amr.corp.intel.com> <20171020075735.GA14378@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 20, 2017 at 08:23:02AM -0700, Dan Williams wrote: > Yes, however it seems these drivers / platforms have been living with > the lack of struct page for a long time. So they either don't use DAX, > or they have a constrained use case that never triggers > get_user_pages(). If it is the latter then they could introduce a new > configuration option that bypasses the pfn_t_devmap() check in > bdev_dax_supported() and fix up the get_user_pages() paths to fail. > So, I'd like to understand how these drivers have been using DAX > support without struct page to see if we need a workaround or we can > go ahead delete this support. If the usage is limited to > execute-in-place perhaps we can do a constrained ->direct_access() for > just that case. For axonram I doubt anyone is using it any more - it was a very for the IBM Cell blades, which were produceѕ in a rather limited number. And Cell basically seems to be dead as far as I can tell. For S/390 Martin might be able to help out what the status of xpram in general and DAX support in particular is. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 20 Oct 2017 18:29:33 +0200 From: Christoph Hellwig To: Dan Williams Cc: Christoph Hellwig , Andrew Morton , Jan Kara , "linux-nvdimm@lists.01.org" , Benjamin Herrenschmidt , Heiko Carstens , "linux-kernel@vger.kernel.org" , linux-xfs@vger.kernel.org, Linux MM , Jeff Moyer , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , linux-fsdevel , Ross Zwisler , Gerald Schaefer Subject: Re: [PATCH v3 02/13] dax: require 'struct page' for filesystem dax Message-ID: <20171020162933.GA26320@lst.de> References: <150846713528.24336.4459262264611579791.stgit@dwillia2-desk3.amr.corp.intel.com> <150846714747.24336.14704246566580871364.stgit@dwillia2-desk3.amr.corp.intel.com> <20171020075735.GA14378@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: On Fri, Oct 20, 2017 at 08:23:02AM -0700, Dan Williams wrote: > Yes, however it seems these drivers / platforms have been living with > the lack of struct page for a long time. So they either don't use DAX, > or they have a constrained use case that never triggers > get_user_pages(). If it is the latter then they could introduce a new > configuration option that bypasses the pfn_t_devmap() check in > bdev_dax_supported() and fix up the get_user_pages() paths to fail. > So, I'd like to understand how these drivers have been using DAX > support without struct page to see if we need a workaround or we can > go ahead delete this support. If the usage is limited to > execute-in-place perhaps we can do a constrained ->direct_access() for > just that case. For axonram I doubt anyone is using it any more - it was a very for the IBM Cell blades, which were produceѕ in a rather limited number. And Cell basically seems to be dead as far as I can tell. For S/390 Martin might be able to help out what the status of xpram in general and DAX support in particular is. -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id 343B46B025F for ; Fri, 20 Oct 2017 12:29:40 -0400 (EDT) Received: by mail-wr0-f199.google.com with SMTP id c42so5993843wrc.13 for ; Fri, 20 Oct 2017 09:29:40 -0700 (PDT) Received: from newverein.lst.de (verein.lst.de. [213.95.11.211]) by mx.google.com with ESMTPS id c10si1008093wrd.350.2017.10.20.09.29.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 20 Oct 2017 09:29:38 -0700 (PDT) Date: Fri, 20 Oct 2017 18:29:33 +0200 From: Christoph Hellwig Subject: Re: [PATCH v3 02/13] dax: require 'struct page' for filesystem dax Message-ID: <20171020162933.GA26320@lst.de> References: <150846713528.24336.4459262264611579791.stgit@dwillia2-desk3.amr.corp.intel.com> <150846714747.24336.14704246566580871364.stgit@dwillia2-desk3.amr.corp.intel.com> <20171020075735.GA14378@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: Christoph Hellwig , Andrew Morton , Jan Kara , "linux-nvdimm@lists.01.org" , Benjamin Herrenschmidt , Heiko Carstens , "linux-kernel@vger.kernel.org" , linux-xfs@vger.kernel.org, Linux MM , Jeff Moyer , Paul Mackerras , Michael Ellerman , Martin Schwidefsky , linux-fsdevel , Ross Zwisler , Gerald Schaefer On Fri, Oct 20, 2017 at 08:23:02AM -0700, Dan Williams wrote: > Yes, however it seems these drivers / platforms have been living with > the lack of struct page for a long time. So they either don't use DAX, > or they have a constrained use case that never triggers > get_user_pages(). If it is the latter then they could introduce a new > configuration option that bypasses the pfn_t_devmap() check in > bdev_dax_supported() and fix up the get_user_pages() paths to fail. > So, I'd like to understand how these drivers have been using DAX > support without struct page to see if we need a workaround or we can > go ahead delete this support. If the usage is limited to > execute-in-place perhaps we can do a constrained ->direct_access() for > just that case. For axonram I doubt anyone is using it any more - it was a very for the IBM Cell blades, which were produceN? in a rather limited number. And Cell basically seems to be dead as far as I can tell. For S/390 Martin might be able to help out what the status of xpram in general and DAX support in particular is. -- 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