From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Subject: Re: [PATCH] writeback: fix hung_task alarm when sync block Date: Wed, 13 Jun 2012 08:59:46 +0800 Message-ID: <20120613005945.GA24091@localhost> References: <1339548774-4834-1-git-send-email-liwp.linux@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Gavin Shan , Jan Kara To: Wanpeng Li Return-path: Content-Disposition: inline In-Reply-To: <1339548774-4834-1-git-send-email-liwp.linux@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Jun 13, 2012 at 08:52:53AM +0800, Wanpeng Li wrote: > From: Wanpeng Li > > I use several dd processes to write a slow SD card > dd if=/dev/sda1 of=/dev/sdc4 bs=1M count=4000 > and several sync commands(maybe > 10),dmesg show this: > > [ 366.888741] INFO: task sync:3518 blocked for more than 120 seconds. > [ 366.888742] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 366.888746] sync D 00000201 0 3518 3462 0x00000000 > Too many similar messages flood the logs. So I use a present method to > fix this issue. > ------------------------------------------ > Author: Mark Lord > Date: Fri Sep 24 09:51:13 2010 -0400 > > block: Prevent hang_check firing during long I/O > ------------------------------------------ > > Signed-off-by: Wanpeng Li Yeah that's also what I'd like to do. So you've tested it? > --- > fs/fs-writeback.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index f2d0109..5d403a1 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -1300,6 +1300,7 @@ void writeback_inodes_sb_nr(struct super_block *sb, > enum wb_reason reason) > { > DECLARE_COMPLETION_ONSTACK(done); > + unsigned long hangcheck; > struct wb_writeback_work work = { > .sb = sb, > .sync_mode = WB_SYNC_NONE, > @@ -1311,7 +1312,12 @@ void writeback_inodes_sb_nr(struct super_block *sb, > > WARN_ON(!rwsem_is_locked(&sb->s_umount)); > bdi_queue_work(sb->s_bdi, &work); > - wait_for_completion(&done); > + hangcheck = sysctl_hung_task_timeout_secs; > + if (hangcheck) The hangcheck variable looks redundant. > + while (!wait_for_completion_timeout(&done, HZ/2)) > + ; > + else > + wait_for_completion(&done); > } > EXPORT_SYMBOL(writeback_inodes_sb_nr); > > -- > 1.7.9.5