From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4703EBE0.7080106@sgi.com> Date: Wed, 03 Oct 2007 12:22:08 -0700 From: Mike Travis MIME-Version: 1.0 Subject: Re: [PATCH 08/10] ia64: Convert cpu_sibling_map to a per_cpu data array (v3) References: <20070912015644.927677070@sgi.com> <20070912015647.214306428@sgi.com> <20070928024901.24ab6c99.pj@sgi.com> In-Reply-To: <20070928024901.24ab6c99.pj@sgi.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Paul Jackson Cc: akpm@linux-foundation.org, ak@suse.de, clameter@sgi.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, sparclinux@vger.kernel.org List-ID: Hi Paul, I just now found this. I'll take a look immediately. I tried it on a couple of systems but not margin. Thanks, Mike Paul Jackson wrote: > Mike, > > I think there is a bug either in this ia64 patch, or in the related > generic arch patch: Convert cpu_sibling_map to be a per cpu variable > (v3). > > It dies early in boot on me, on the SGI internal 8 processor IA64 > system that you and I know as 'margin'. The death is a hard hang, due > to a corrupt stack, due to a bogus cpu index. > > I haven't tracked it down all the way, but have gotten this far. If I add > the following patch, I get a panic on the BUG_ON if I have these two patches > in 2.6.23-rc8-mm1, but it boots just fine if I don't have these two patches. > > It seems that the "cpu_sibling_map[cpu]" cpumask_t is empty (all zero > bits) with your two patches applied, but has some non-zero bits > otherwise, which leads to 'group' being NR_CPUS instead of a useful CPU > number. Unfortunately, I have no idea why the "cpu_sibling_map[cpu]" > cpumask_t is empty -- good luck on that part. > > The patch that catches this bug earlier is this: > > --- 2.6.23-rc8-mm1.orig/kernel/sched.c 2007-09-28 01:42:20.144561024 -0700 > +++ 2.6.23-rc8-mm1/kernel/sched.c 2007-09-28 02:27:14.239075497 -0700 > @@ -5905,6 +5905,7 @@ static int cpu_to_phys_group(int cpu, co > #else > group = cpu; > #endif > + BUG_ON(group == NR_CPUS); > if (sg) > *sg = &per_cpu(sched_group_phys, group); > return group; > > -- 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