From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from omx2.sgi.com (omx2-ext.sgi.com [192.48.171.19]) by ozlabs.org (Postfix) with ESMTP id 435E0679F0 for ; Tue, 4 Apr 2006 03:42:05 +1000 (EST) Date: Mon, 3 Apr 2006 10:42:02 -0700 (PDT) From: Christoph Lameter To: Nathan Lynch Subject: Re: Fw: 2.6.16 crashes when running numastat on p575 In-Reply-To: <20060403141027.GB25663@localdomain> Message-ID: References: <20060402213216.2e61b74e.akpm@osdl.org> <20060402221513.96f05bdc.pj@sgi.com> <20060403141027.GB25663@localdomain> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: Christoph Lameter Cc: akpm@osdl.org, linuxppc-dev@ozlabs.org, Paul Jackson , ak@suse.com, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 3 Apr 2006, Nathan Lynch wrote: > In this case, disabling preempt around the for_each_online_cpu loop > would prevent any cpu from going down in the meantime. But since this > function doesn't look like it's a hot path, and we're potentially > traversing lots of zones and cpus, lock_cpu_hotplug might be preferable. > > As Paul noted, the fix as it stands isn't adequate. There are many other for_each_*_cpu loops in the kernel that do not have any of the instrumentation you suggest. I suggest you come up with a general solution and then go through all of them and fix this. Please be aware that many of these loops are performance critical.