From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f174.google.com (mail-wi0-f174.google.com [209.85.212.174]) by kanga.kvack.org (Postfix) with ESMTP id A2F946B0098 for ; Fri, 29 May 2015 15:34:34 -0400 (EDT) Received: by wicmc15 with SMTP id mc15so24393123wic.1 for ; Fri, 29 May 2015 12:34:34 -0700 (PDT) Received: from mail-wg0-f43.google.com (mail-wg0-f43.google.com. [74.125.82.43]) by mx.google.com with ESMTPS id ey5si11355754wjd.74.2015.05.29.12.34.32 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 29 May 2015 12:34:33 -0700 (PDT) Received: by wgez8 with SMTP id z8so70848183wge.0 for ; Fri, 29 May 2015 12:34:32 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1432924340.23540.78.camel@misato.fc.hp.com> References: <1432739944-22633-1-git-send-email-toshi.kani@hp.com> <1432739944-22633-13-git-send-email-toshi.kani@hp.com> <20150529091129.GC31435@pd.tnic> <1432911782.23540.55.camel@misato.fc.hp.com> <1432924340.23540.78.camel@misato.fc.hp.com> Date: Fri, 29 May 2015 12:34:32 -0700 Message-ID: Subject: Re: [PATCH v10 12/12] drivers/block/pmem: Map NVDIMM with ioremap_wt() From: Dan Williams Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani Cc: Borislav Petkov , Ross Zwisler , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Andrew Morton , Arnd Bergmann , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" , X86 ML , "linux-nvdimm@lists.01.org" , Juergen Gross , Stefan Bader , Andy Lutomirski , Henrique de Moraes Holschuh , Yigal Korman , Konrad Rzeszutek Wilk , "Elliott, Robert (Server Storage)" , Luis Rodriguez , Christoph Hellwig , Matthew Wilcox On Fri, May 29, 2015 at 11:32 AM, Toshi Kani wrote: > On Fri, 2015-05-29 at 11:19 -0700, Dan Williams wrote: >> On Fri, May 29, 2015 at 8:03 AM, Toshi Kani wrote: >> > On Fri, 2015-05-29 at 07:43 -0700, Dan Williams wrote: >> >> On Fri, May 29, 2015 at 2:11 AM, Borislav Petkov wrote: >> >> > On Wed, May 27, 2015 at 09:19:04AM -0600, Toshi Kani wrote: >> >> >> The pmem driver maps NVDIMM with ioremap_nocache() as we cannot > : >> >> >> - pmem->virt_addr = ioremap_nocache(pmem->phys_addr, pmem->size); >> >> >> + pmem->virt_addr = ioremap_wt(pmem->phys_addr, pmem->size); >> >> >> if (!pmem->virt_addr) >> >> >> goto out_release_region; >> >> > >> >> > Dan, Ross, what about this one? >> >> > >> >> > ACK to pick it up as a temporary solution? >> >> >> >> I see that is_new_memtype_allowed() is updated to disallow some >> >> combinations, but the manual seems to imply any mixing of memory types >> >> is unsupported. Which worries me even in the current code where we >> >> have uncached mappings in the driver, and potentially cached DAX >> >> mappings handed out to userspace. >> > >> > is_new_memtype_allowed() is not to allow some combinations of mixing of >> > memory types. When it is allowed, the requested type of ioremap_xxx() >> > is changed to match with the existing map type, so that mixing of memory >> > types does not happen. >> >> Yes, but now if the caller was expecting one memory type and gets >> another one that is something I think the driver would want to know. >> At a minimum I don't think we want to get emails about pmem driver >> performance problems when someone's platform is silently degrading WB >> to UC for example. > > The pmem driver creates an ioremap map to an NVDIMM range first. So, > there will be no conflict at this point, unless there is a conflicting > driver claiming the same NVDIMM range. Hmm, I thought it would be WB due to this comment in is_new_memtype_allowed() /* * PAT type is always WB for untracked ranges, so no need to check. */ -- 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