From: Artem Bityutskiy Subject: Re: [PATCH 2/2] ext4: implement cgroup writeback support Date: Wed, 23 Sep 2015 15:49:12 +0300 Message-ID: <1443012552.19983.209.camel@gmail.com> References: <1434495193-31182-1-git-send-email-tj@kernel.org> <1434495193-31182-3-git-send-email-tj@kernel.org> <20150722035620.GD2944@thunk.org> Reply-To: dedekind1@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, lizefan@huawei.com, cgroups@vger.kernel.org, hannes@cmpxchg.org, kernel-team@fb.com, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org To: Theodore Ts'o , Tejun Heo Return-path: In-Reply-To: <20150722035620.GD2944@thunk.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Tue, 2015-07-21 at 23:56 -0400, Theodore Ts'o wrote: > > v2: Updated for MS_CGROUPWB -> SB_I_CGROUPWB. > > > > Signed-off-by: Tejun Heo > > Cc: "Theodore Ts'o" > > Cc: Andreas Dilger > > Cc: linux-ext4@vger.kernel.org > > Thanks, applied. Hi, this patch introduces a regression - a major one, I'd say. Symptoms: copy a bunch of file, run sync, then run 'reboot', and after you boot up the copied files are corrupted. So basically the user -visible symptom is that 'sync' does not work. I quite an effort to bisect it, but it led me to this patch. If I take the latest upstream (v4.3-rc2+), and revert this patch: 001e4a8 ext4: imlpement cgroup writeback support then the problem goes away - files are not corrupted after reboot. I use ext4 on top of a "bare" partition, no LVM or dm layers involved. I use Fedora 22 with all the latest package updates, and I only change the kernel there. The corruption seems to be that the start with a bunch of zeroes instead of the real data, but I did not check carefully, looked only at one file briefly. Artem.