From: Jan Kara Subject: Re: [PATCH v4 10/12] dax: add struct iomap based DAX PMD support Date: Wed, 5 Oct 2016 07:50:20 +0200 Message-ID: <20161005055020.GB20752@quack2.suse.cz> References: <1475189370-31634-1-git-send-email-ross.zwisler@linux.intel.com> <1475189370-31634-11-git-send-email-ross.zwisler@linux.intel.com> <20161003105949.GP6457@quack2.suse.cz> <20161003210557.GA28177@linux.intel.com> <20161004055557.GB17515@quack2.suse.cz> <20161004153948.GA21248@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Theodore Ts'o , Matthew Wilcox , Dave Chinner , linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Andreas Dilger , Alexander Viro , Jan Kara , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jan Kara , Andrew Morton , linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christoph Hellwig To: Ross Zwisler Return-path: Content-Disposition: inline In-Reply-To: <20161004153948.GA21248-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org On Tue 04-10-16 09:39:48, Ross Zwisler wrote: > > The gfp_mask that propagates from __do_fault() or do_page_mkwrite() is fine > > because at that point it is correct. But once we grab filesystem locks > > which are not reclaim safe, we should update vmf->gfp_mask we pass further > > down into DAX code to not contain __GFP_FS (that's a bug we apparently have > > there). And inside DAX code, we definitely are not generally safe to add > > __GFP_FS to mapping_gfp_mask(). Maybe we'd be better off propagating struct > > vm_fault into this function, using passed gfp_mask there and make sure > > callers update gfp_mask as appropriate. > > Yep, that makes sense to me. In reviewing your set it also occurred to me that > we might want to stick a struct vm_area_struct *vma pointer in the vmf, since > you always need a vma when you are using a vmf, but we pass them as a pair > everywhere. Actually, vma pointer will be in struct vm_fault after my DAX write-protection series. So once that lands, we can clean up whatever duplicit function parameters... Honza -- Jan Kara SUSE Labs, CR