Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932298AbVISFLG (ORCPT ); Mon, 19 Sep 2005 01:11:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932306AbVISFLG (ORCPT ); Mon, 19 Sep 2005 01:11:06 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.144]:43693 "EHLO e4.ny.us.ibm.com") by vger.kernel.org with ESMTP id S932298AbVISFLE (ORCPT ); Mon, 19 Sep 2005 01:11:04 -0400 Date: Mon, 19 Sep 2005 10:40:24 +0530 From: Srivatsa Vaddagiri To: "Li, Shaohua" Cc: Nigel Cunningham , Andrew Morton , Linus Torvalds , Zwane Mwaikambo , Linux Kernel Mailing List , Rusty Russell , Ingo Molnar Subject: Re: PATCH: Fix race in cpu_down (hotplug cpu) Message-ID: <20050919051024.GA8653@in.ibm.com> Reply-To: vatsa@in.ibm.com References: <59D45D057E9702469E5775CBB56411F171F7E0@pdsmsx406> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <59D45D057E9702469E5775CBB56411F171F7E0@pdsmsx406> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 858 Lines: 25 On Mon, Sep 19, 2005 at 12:48:38PM +0800, Li, Shaohua wrote: > I guess Nigel's point is cpu_idle is preempted before take_cpu_down. If > the preempt occurs after the cpu_is_offline check, when the cpu (after How can that happen? Idle task is running at max priority (MAX_RT_PRIO-1) and with SCHED_FIFO policy at this point. If that is indeed happening, then we need to modify sched_idle_next not to allow that. > sched_idle_next) goes into idle again, nobody can wake it up. Nigel, > isn't it? -- Thanks and Regards, Srivatsa Vaddagiri, Linux Technology Center, IBM Software Labs, Bangalore, INDIA - 560017 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/