From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 28 Jun 2018 10:30:20 -0600 From: Ross Zwisler To: Matthew Wilcox Cc: Ross Zwisler , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jan Kara , Jeff Layton , Lukas Czerner , Christoph Hellwig , Goldwyn Rodrigues , Nicholas Piggin , Ryusuke Konishi , linux-nilfs@vger.kernel.org, Jaegeuk Kim , Chao Yu , linux-f2fs-devel@lists.sourceforge.net Subject: Re: [PATCH v14 00/74] Convert page cache to XArray Message-ID: <20180628163020.GA18192@linux.intel.com> References: <20180617020052.4759-1-willy@infradead.org> <20180619031257.GA12527@linux.intel.com> <20180619092230.GA1438@bombadil.infradead.org> <20180619164037.GA6679@linux.intel.com> <20180619171638.GE1438@bombadil.infradead.org> <20180627110529.GA19606@bombadil.infradead.org> <20180627194438.GA20774@linux.intel.com> <20180628083909.GA7646@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180628083909.GA7646@bombadil.infradead.org> Sender: owner-linux-mm@kvack.org List-ID: On Thu, Jun 28, 2018 at 01:39:09AM -0700, Matthew Wilcox wrote: > On Wed, Jun 27, 2018 at 01:44:38PM -0600, Ross Zwisler wrote: > > On Wed, Jun 27, 2018 at 04:05:29AM -0700, Matthew Wilcox wrote: > > > On Tue, Jun 19, 2018 at 10:16:38AM -0700, Matthew Wilcox wrote: > > > > I think I see a bug. No idea if it's the one you're hitting ;-) > > > > > > > > I had been intending to not use the 'entry' to decide whether we were > > > > waiting on a 2MB or 4kB page, but rather the xas. I shelved that idea, > > > > but not before dropping the DAX_PMD flag being passed from the PMD > > > > pagefault caller. So if I put that back ... > > > > > > Did you get a chance to test this? > > > > With this patch it doesn't deadlock, but the test dies with a SIGBUS and we > > hit a WARN_ON in the DAX code: > > > > WARNING: CPU: 5 PID: 1678 at fs/dax.c:226 get_unlocked_entry+0xf7/0x120 > > > > I don't have a lot of time this week to debug further. The quickest path to > > victory is probably for you to get this reproducing in your test setup. Does > > XFS + DAX + generic/340 pass for you? > > I won't be back in front of my test box until Tuesday, but that test > does work for me because I couldn't get your instructions to give me a > 2MB aligned DAX setup. I had to settle for 4k, so none of the 2MB stuff > has been tested properly. Ah. I've documented both my qemu setup and my filesystem setup here: https://nvdimm.wiki.kernel.org/pmem_in_qemu https://nvdimm.wiki.kernel.org/2mib_fs_dax This should be enough to get you up and running in QEMU and able to reliably get filesystem DAX PMD faults.