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