From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id m9R84l0O014839 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 27 Oct 2008 17:04:47 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id EA1EC1B801F for ; Mon, 27 Oct 2008 17:04:46 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (s6.gw.fujitsu.co.jp [10.0.50.96]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id C0BCC2DC015 for ; Mon, 27 Oct 2008 17:04:46 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 9C14D1DB803F for ; Mon, 27 Oct 2008 17:04:46 +0900 (JST) Received: from ml12.s.css.fujitsu.com (ml12.s.css.fujitsu.com [10.249.87.102]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 57C371DB803C for ; Mon, 27 Oct 2008 17:04:46 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [RFC][PATCH] lru_add_drain_all() don't use schedule_on_each_cpu() In-Reply-To: <1225094190.16159.3.camel@twins> References: <20081027120405.1B45.KOSAKI.MOTOHIRO@jp.fujitsu.com> <1225094190.16159.3.camel@twins> Message-Id: <20081027170156.9659.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Mon, 27 Oct 2008 17:03:51 +0900 (JST) Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: kosaki.motohiro@jp.fujitsu.com, Heiko Carstens , Nick Piggin , linux-kernel@vger.kernel.org, Hugh Dickins , Andrew Morton , Linus Torvalds , Rik van Riel , Lee Schermerhorn , linux-mm@kvack.org, Christoph Lameter , Gautham Shenoy , Oleg Nesterov , Rusty Russell , mpm List-ID: > On Mon, 2008-10-27 at 12:14 +0900, KOSAKI Motohiro wrote: > > > Right, and would be about 4k+sizeof(task_struct), some people might be > > > bothered, but most won't care. > > > > > > > Perhaps, I misunderstand your intension. so can you point your > > > > previous discussion url? > > > > > > my google skillz fail me, but once in a while people complain that we > > > have too many kernel threads. > > > > > > Anyway, if we can re-use this per-cpu workqueue for more goals, I guess > > > there is even less of an objection. > > > > In general, you are right. > > but this is special case. mmap_sem is really widely used various subsystem and drivers. > > (because page fault via copy_user introduce to depend on mmap_sem) > > > > Then, any work-queue reu-sing can cause similar dead-lock easily. > > Yeah, I know, and the cpu-hotplug discussion needed another thread due > to yet another locking incident. I was hoping these two could go > together. Yeah, I found its thread. (I think it is "work_on_cpu: helper for doing task on a CPU.", right?) So I'll read it soon. Please wait a bit. > > Neither are general-purpose workqueues, both need to stay away from the > normal eventd due to deadlocks. > > ego, does you extra thread ever use mmap_sem? -- 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