From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261644AbUBVCXb (ORCPT ); Sat, 21 Feb 2004 21:23:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261642AbUBVCXb (ORCPT ); Sat, 21 Feb 2004 21:23:31 -0500 Received: from dp.samba.org ([66.70.73.150]:34215 "EHLO lists.samba.org") by vger.kernel.org with ESMTP id S261644AbUBVCX3 (ORCPT ); Sat, 21 Feb 2004 21:23:29 -0500 From: Rusty Russell To: Pavel Machek Cc: akpm@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Booting when CPUs fail to come up. In-reply-to: Your message of "Sat, 21 Feb 2004 14:33:59 BST." <20040221133359.GA339@elf.ucw.cz> Date: Sun, 22 Feb 2004 12:43:04 +1100 Message-Id: <20040222022340.E9D132C361@lists.samba.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In message <20040221133359.GA339@elf.ucw.cz> you write: > Hi! > > > > > I recently played with setting a bit in cpu_possible_map that wasn't > > > > in cpu_online_map: this can happen without hotplug CPU when a CPU > > > > fails to boot, for example. > > > > > > Is it safe to continue when one cpu is apparently malfunctioning? > > > > Well, patch was overzealous and no longer required. > > > > But we shouldn't crash when this happens just because a CPU didn't > > come up. > > I still do not agree. You're entitled. However, on x86 we booted before when a secondary CPU didn't come up, and the patch was designed to ensure that we still did so. > You have a system you tried to kick CPU #13 alive, and something very > wrong happened, CPU #13 did not come up. It is there, has full access > to memory, it is probably running some kind of program.... No, it's possible, but not online. This actually happens on archs where you have hotplug cpus, as well as x86 boot failures. > I'd not dare mount disks read-write in such situation and I believe > crashing early is actually right thing to do. Sure, send a patch for x86 to do that, and we can discuss that. I'm not going to break existing behavior by stealth though. Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell.