From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: block allocator issue with ext4+DAX Date: Thu, 31 Mar 2016 10:59:25 +0200 Message-ID: <20160331085925.GC11041@quack.suse.cz> References: <20160330220129.GA9101@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , Theodore Ts'o , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Ross Zwisler Return-path: Content-Disposition: inline In-Reply-To: <20160330220129.GA9101@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Wed 30-03-16 16:01:29, Ross Zwisler wrote: > I've hit an issue in my testing which I believe to be related to the ext4 > block allocator when using the DAX mount option. I originally found this > issue with the generic/102 xfstest, but have reduced it to the minimal > reproducer at the bottom of this email. I've been able to reproduce this with > both BRD and with PMEM as the underlying block device. > > For this test we're running in a very small filesystem, only 512 MiB. We > fallocate() 400 MiB of that space, unlink the file, then try and rewrite that > 400 MiB file one chunk at a time. > > What actually happens is that during the rewrite we run out of memory and the > DAX call to get_block() in dax_io() fails with -ENOSPC. Yes, I have already sent a fix for this bug here: http://www.spinics.net/lists/linux-ext4/msg51649.html Ted, can you please pick it up? Thanks! Honza -- Jan Kara SUSE Labs, CR