From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH 1/2] mm: Make task in balance_dirty_pages() killable
Date: Tue, 15 Nov 2011 19:48:44 +0800
Message-ID: <20111115114844.GA11665@localhost>
References: <1321287324-15121-1-git-send-email-jack@suse.cz>
 <1321287324-15121-2-git-send-email-jack@suse.cz>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Christoph Hellwig <hch@infradead.org>,
	Al Viro <viro@ZenIV.linux.org.uk>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
To: Jan Kara <jack@suse.cz>
Return-path: <linux-fsdevel-owner@vger.kernel.org>
Received: from mga03.intel.com ([143.182.124.21]:1683 "EHLO mga03.intel.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1753227Ab1KOLst (ORCPT <rfc822;linux-fsdevel@vger.kernel.org>);
	Tue, 15 Nov 2011 06:48:49 -0500
Content-Disposition: inline
In-Reply-To: <1321287324-15121-2-git-send-email-jack@suse.cz>
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

> +static int balance_dirty_pages(struct address_space *mapping,
>  				unsigned long pages_dirtied)
>  {
>  	unsigned long nr_reclaimable;	/* = file_dirty + unstable_nfs */
> @@ -1020,6 +1023,7 @@ static void balance_dirty_pages(struct address_space *mapping,
>  	unsigned long pos_ratio;
>  	struct backing_dev_info *bdi = mapping->backing_dev_info;
>  	unsigned long start_time = jiffies;
> +	int err = 0;
>  
>  	for (;;) {
>  		/*
> @@ -1133,7 +1137,7 @@ pause:
>  					  pages_dirtied,
>  					  pause,
>  					  start_time);
> -		__set_current_state(TASK_UNINTERRUPTIBLE);
> +		__set_current_state(TASK_KILLABLE);
>  		io_schedule_timeout(pause);
>  
>  		dirty_thresh = hard_dirty_limit(dirty_thresh);
> @@ -1145,6 +1149,11 @@ pause:
>  		 */
>  		if (nr_dirty < dirty_thresh)
>  			break;
> +
> +		if (fatal_signal_pending(current)) {
> +			err = -EINTR;
> +			break;
> +		}
>  	}
  
The other alternative is to raise the limit on fatal_signal_pending:

                if (fatal_signal_pending(current) && 
                    nr_dirty < dirty_thresh + dirty_thresh / 2)
                        break;

That should work well enough in practice and avoids touching the fs code.

Thanks,
Fengguang