Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753906Ab2FMBNH (ORCPT ); Tue, 12 Jun 2012 21:13:07 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:64999 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753665Ab2FMBMU (ORCPT ); Tue, 12 Jun 2012 21:12:20 -0400 Date: Wed, 13 Jun 2012 09:12:04 +0800 From: Wanpeng Li To: Fengguang Wu Cc: Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Gavin Shan , Wanpeng Li Subject: Re: [PATCH] writeback: fix hung_task alarm when sync block Message-ID: <20120613011151.GA2181@kernel> Reply-To: Wanpeng Li References: <1339548774-4834-1-git-send-email-liwp.linux@gmail.com> <20120613005945.GA24091@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120613005945.GA24091@localhost> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2511 Lines: 76 On Wed, Jun 13, 2012 at 08:59:46AM +0800, Fengguang Wu wrote: >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? Not yet, I will test it today. > >> --- >> 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. if sysctl_hung_task_timeout_secs is equal to ZERO, it means infinite timeout -- no checking done. So I think wait_for_completion_timeout makes no sense this time. Regards, Wanpeng Li > >> + while (!wait_for_completion_timeout(&done, HZ/2)) >> + ; >> + else >> + wait_for_completion(&done); >> } >> EXPORT_SYMBOL(writeback_inodes_sb_nr); >> >> -- >> 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/