From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot0-f177.google.com ([74.125.82.177]:33677 "EHLO mail-ot0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752553AbdBFQYz (ORCPT ); Mon, 6 Feb 2017 11:24:55 -0500 Received: by mail-ot0-f177.google.com with SMTP id 73so65727618otj.0 for ; Mon, 06 Feb 2017 08:24:55 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20170206143648.GA461@infradead.org> References: <148615748258.43180.1690152053774975329.stgit@djiang5-desk3.ch.intel.com> <20170206143648.GA461@infradead.org> From: Dan Williams Date: Mon, 6 Feb 2017 08:24:48 -0800 Message-ID: Subject: Re: [PATCH] mm: replace FAULT_FLAG_SIZE with parameter to huge_fault Content-Type: text/plain; charset=UTF-8 Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Christoph Hellwig Cc: Dave Jiang , Matthew Wilcox , "linux-nvdimm@lists.01.org" , Dave Hansen , linux-xfs@vger.kernel.org, Linux MM , "Kirill A. Shutemov" , Jan Kara , Andrew Morton , linux-ext4 , Vlastimil Babka On Mon, Feb 6, 2017 at 6:36 AM, Christoph Hellwig wrote: > On Fri, Feb 03, 2017 at 02:31:22PM -0700, Dave Jiang wrote: >> Since the introduction of FAULT_FLAG_SIZE to the vm_fault flag, it has >> been somewhat painful with getting the flags set and removed at the >> correct locations. More than one kernel oops was introduced due to >> difficulties of getting the placement correctly. Removing the flag >> values and introducing an input parameter to huge_fault that indicates >> the size of the page entry. This makes the code easier to trace and >> should avoid the issues we see with the fault flags where removal of the >> flag was necessary in the fallback paths. > > Why is this not in struct vm_fault? Because this is easier to read and harder to get wrong. Same arguments as getting rid of struct blk_dax_ctl. > Also can be use this opportunity > to fold ->huge_fault into ->fault? Hmm, yes, just need a scheme to not attempt huge_faults on pte-only handlers.