From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 0/2] Make task doing heavy writing killable
Date: Mon, 14 Nov 2011 07:05:46 -0500
Message-ID: <20111114120546.GA31037@infradead.org>
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Cc: Jan Kara <jack@suse.cz>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	Al Viro <viro@ZenIV.linux.org.uk>,
	"k-mio@sx.jp.nec.com" <k-mio@sx.jp.nec.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Christoph Hellwig <hch@infradead.org>
To: Wu Fengguang <fengguang.wu@intel.com>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
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On Mon, Nov 14, 2011 at 07:59:12PM +0800, Wu Fengguang wrote:
> On Mon, Nov 14, 2011 at 07:10:28PM +0800, Jan Kara wrote:
> > 
> >   Hello,
> > 
> >   these two patches aim at making task waiting in balance_dirty_pages()
> > killable.  This is desirable because otherwise if filesystem stops accepting
> > writes (e.g. if device has been removed or other serious error condidion) we
> > have a task stuck in D state forever.
> 
> Agreed totally. I myself has run into such conditions and get very
> annoyed not being able to kill the hard throttled tasks -- they just
> stuck there for ever if the error condition does not change.
> 
> >   I'm not sure who should merge these two patches... Al, Fengguang?
> 
> I'd like to do it -- otherwise there will obviously be merge conflicts.
> 
> Actually I also queued a patch to do this (attached). Your patches do
> better on TASK_KILLABLE and the use of signal_pending() in write
> routines, while mine goes further to add the break to various
> filesystems.  How about combining them together?

Can you make balance_dirty_pages(_ratelimited) return an error instead
of opencoding the fatal signal check everywhere?  That would make the
interface a bit more obvious.