From: Simon Jeons <simon.jeons@gmail.com>
To: Dave Jones <davej@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>,
linux-mm@kvack.org, Linux Kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org
Subject: Re: livelock in __writeback_inodes_wb ?
Date: Tue, 11 Dec 2012 20:26:22 -0600 [thread overview]
Message-ID: <1355279182.1532.4.camel@kernel.cn.ibm.com> (raw)
In-Reply-To: <20121211142942.GA1943@redhat.com>
On Tue, 2012-12-11 at 09:29 -0500, Dave Jones wrote:
> On Tue, Dec 11, 2012 at 04:23:27PM +0800, Fengguang Wu wrote:
> > On Wed, Nov 28, 2012 at 09:55:15AM -0500, Dave Jones wrote:
> > > We had a user report the soft lockup detector kicked after 22
> > > seconds of no progress, with this trace..
> >
> > Where is the original report? The reporter may help provide some clues
> > on the workload that triggered the bug.
>
> https://bugzilla.redhat.com/show_bug.cgi?id=880949
>
> > The bug reporter should know best whether there are heavy IO.
> >
> > However I suspect it's not directly caused by heavy IO: we will
> > release &wb->list_lock before each __writeback_single_inode() call,
> > which starts writeback IO for each inode.
> >
> > > Should there be something in this loop periodically poking
> > > the watchdog perhaps ?
> >
> > It seems we failed to release &wb->list_lock in wb_writeback() for
> > long time (dozens of seconds). That is, the inode_sleep_on_writeback()
> > is somehow not called. However it's not obvious to me how come this
> > can happen..
>
> Right, it seems that we only drop the lock when there is more work to do.
> And if there is no work to do, then we would have bailed from the loop.
If no work to do, lock will be dropped after for loop.
>
> mysterious.
>
> Dave
>
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prev parent reply other threads:[~2012-12-12 2:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-28 14:55 livelock in __writeback_inodes_wb ? Dave Jones
2012-12-11 8:23 ` Fengguang Wu
2012-12-11 13:41 ` Jan Kara
2012-12-14 9:13 ` Fengguang Wu
2012-12-11 14:29 ` Dave Jones
2012-12-12 2:26 ` Simon Jeons [this message]
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