From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marco Stornelli Subject: Re: BUG: enabling psacct breaks fsfreeze Date: Fri, 02 Nov 2012 10:50:50 +0100 Message-ID: <5093977A.9010507@gmail.com> References: <20121023094351.GC27919@pcnci.linuxbox.cz> <20121031121517.GD18424@quack.suse.cz> <20121031124600.GM20752@pcnci.linuxbox.cz> <20121101093723.GC6584@quack.suse.cz> <20121101111957.GD6584@quack.suse.cz> <20121101142325.GD20752@pcnci.linuxbox.cz> <20121101225053.GB31937@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Nikola Ciprich , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Jan Kara Return-path: In-Reply-To: <20121101225053.GB31937@quack.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Il 01/11/2012 23:50, Jan Kara ha scritto: > On Thu 01-11-12 15:23:25, Nikola Ciprich wrote: >> Nov 1 14:23:25 vmnci22 [ 1075.178123] SysRq : Show Blocked State >> Nov 1 14:23:25 vmnci22 [ 1075.180555] task PC stack pid father >> Nov 1 14:23:25 vmnci22 [ 1075.180592] fsfreeze D 0000000000000000 0 4215 4195 0x00000000 >> Nov 1 14:23:25 vmnci22 [ 1075.180599] ffff8800090b9b28 0000000000000046 0000000000000000 ffffffff00000000 >> Nov 1 14:23:25 vmnci22 [ 1075.180606] 0000000000013780 ffff8800090b9fd8 ffff88000f716170 ffff88000f715e80 >> Nov 1 14:23:25 vmnci22 [ 1075.180612] ffff88000f715dc0 ffffffff81566080 ffff88000f716170 000000010002f405 >> Nov 1 14:23:25 vmnci22 [ 1075.180619] Call Trace: >> Nov 1 14:23:25 vmnci22 [ 1075.180693] [] __generic_file_aio_write+0xbb/0x420 >> Nov 1 14:23:25 vmnci22 [ 1075.180729] [] ? autoremove_wake_function+0x0/0x40 >> Nov 1 14:23:25 vmnci22 [ 1075.180736] [] generic_file_aio_write+0x5f/0xc0 > Thanks. So the system isn't really deadlocked. It's just that fsfreeze > command hangs, isn't it? OK, I understand that it's kind of incovenient > situation because every command will hang like this when the filesystem is > frozen. > > Now I only have to come up with a way to improve this... It isn't quite > simple - to properly protect against freezing be have to communicate down > into generic_file_aio_write() that we want to bail out if filesystem is > frozen instead of waiting. > > Honza > I saw this behavior (task-hang) when I tested the fsfreeze code. I was writing a little patch to replace fsfreeze's wait queue with a killable queue, in this way the user can do at least "kill -9", but since the behavior was the same before your patch I didn't send it. I don't know if we can break any previous behavior. The funny thing here is that it's like if fsfreeze freezes itself :) Marco