From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected Date: Tue, 26 Aug 2008 00:46:07 -0700 (PDT) Message-ID: <20080826.004607.253712060.davem@davemloft.net> References: <20080826072220.GB31876@elte.hu> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080826072220.GB31876-X9Un+BFzKDI@public.gmane.org> Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: Text/Plain; charset="us-ascii" To: mingo-X9Un+BFzKDI@public.gmane.org Cc: torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, Alan.Brunelle-VXdhtT5mjnY@public.gmane.org, travis-sJ/iWh9BUns@public.gmane.org, tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org, rjw-KKrjLPT3xs0@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-testers-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, arjan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org From: Ingo Molnar Date: Tue, 26 Aug 2008 09:22:20 +0200 > And i guess the next generation of 4K CPUs support should just get away > from cpumask_t-on-kernel-stack model altogether, as the current model is > not maintainable. We tried the on-kernel-stack variant, and it really > does not work reliably. We can fix this in v2.6.28. I recenetly did some work on sparc64 to use cpumask pointers as much as possible. The only case that didn't work was due to a limitation in arch interfaces for the new generic smp_call_function() code. It passes a cpumask_t instead of a pointer to one via arch_send_call_function_ipi(). But other than that, the whole sparc64 SMP stuff uses cpumask_t pointers only. What it comes down to is that you have to do the "self cpu" and other tests in the cross-call dispatch routines themselves, instead of at the top-level working on cpumask_t objects. Otherwise you have to modify cpumask_t objects and thus pluck them onto the stack where they take up silly amounts of space.