From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 83EEE6B004A for ; Tue, 14 Sep 2010 04:44:42 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o8E8ie6P018533 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Tue, 14 Sep 2010 17:44:40 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id E032245DE52 for ; Tue, 14 Sep 2010 17:44:39 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id B8F1145DE50 for ; Tue, 14 Sep 2010 17:44:39 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 7FEC21DB803F for ; Tue, 14 Sep 2010 17:44:39 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 3A9251DB803B for ; Tue, 14 Sep 2010 17:44:39 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH 05/17] writeback: quit throttling when signal pending In-Reply-To: <20100914083338.GA20295@localhost> References: <20100914172028.C9B2.A69D9226@jp.fujitsu.com> <20100914083338.GA20295@localhost> Message-Id: <20100914174017.C9BB.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Tue, 14 Sep 2010 17:44:37 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: kosaki.motohiro@jp.fujitsu.com, Neil Brown , linux-mm , LKML , Andrew Morton , Theodore Ts'o , Dave Chinner , Jan Kara , Peter Zijlstra , Mel Gorman , Rik van Riel , Chris Mason , Christoph Hellwig , "Li, Shaohua" List-ID: > On Tue, Sep 14, 2010 at 04:23:56PM +0800, KOSAKI Motohiro wrote: > > > Subject: writeback: quit throttling when fatal signal pending > > > From: Wu Fengguang > > > Date: Wed Sep 08 17:40:22 CST 2010 > > > > > > This allows quick response to Ctrl-C etc. for impatient users. > > > > > > It mainly helps the rare bdi/global dirty exceeded cases. > > > In the normal case of not exceeded, it will quit the loop anyway. > > > > > > CC: Neil Brown > > > Signed-off-by: Wu Fengguang > > > --- > > > mm/page-writeback.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > --- linux-next.orig/mm/page-writeback.c 2010-09-12 13:25:23.000000000 +0800 > > > +++ linux-next/mm/page-writeback.c 2010-09-13 11:39:33.000000000 +0800 > > > @@ -552,6 +552,9 @@ static void balance_dirty_pages(struct a > > > __set_current_state(TASK_INTERRUPTIBLE); > > > io_schedule_timeout(pause); > > > > > > + if (fatal_signal_pending(current)) > > > + break; > > > + > > > check_exceeded: > > > /* > > > * The bdi thresh is somehow "soft" limit derived from the > > > > I think we need to change callers (e.g. generic_perform_write) too. > > Otherwise, plenty write + SIGKILL combination easily exceed dirty limit. > > It mean we can see strange OOM. > > If it's dangerous, we can do without this patch. How? > The users can still > get quick response in normal case after all. > > However, I suspect the process is guaranteed to exit on > fatal_signal_pending, so it won't dirty more pages :) Process exiting is delayed until syscall exiting. So, we exit write syscall manually if necessary. Am I missing anything? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org