Re: SMP Panic caused by [PATCH] sched: consolidate sched domains

[William Lee Irwin III <wli@holomorphy.com>]

> On Sun, 2004-08-29 at 13:03, William Lee Irwin III wrote:
> >> -#define node_to_cpumask(node)	(cpu_online_map)
> >> +#define node_to_cpumask(node)	(cpu_possible_map)
> 
> On Sun, Aug 29, 2004 at 01:09:49PM -0400, James Bottomley wrote:
> > I really don't think so.  This macro is also used at runtime, so there
> > it would return CPUs that aren't online.
> > It does look like all runtime uses in sched.c pass node_to_cpumask
> > through any_online_cpu(), so at least for the scheduler, the change may
> > be safe, but you'd have to audit all other runtime uses.

On Sun, Aug 29, 2004 at 10:22:50AM -0700, William Lee Irwin III wrote:
> ./drivers/base/node.c:22:	cpumask_t mask = node_to_cpumask(node_dev->sysdev.id);
> ./arch/ia64/sn/io/sn2/ml_SN_intr.c:63:		cpu = first_cpu(node_to_cpumask(cnode));

Okay, how about:


Index: wait-2.6.9-rc1-mm1/kernel/sched.c
===================================================================
--- wait-2.6.9-rc1-mm1.orig/kernel/sched.c	2004-08-28 11:41:47.000000000 -0700
+++ wait-2.6.9-rc1-mm1/kernel/sched.c	2004-08-29 10:25:00.468546856 -0700
@@ -4262,16 +4262,21 @@
 						&cpu_to_isolated_group);
 	}
 
-	/* Set up physical groups */
-	for (i = 0; i < MAX_NUMNODES; i++) {
-		cpumask_t nodemask = node_to_cpumask(i);
-
-		cpus_and(nodemask, nodemask, cpu_default_map);
-		if (cpus_empty(nodemask))
-			continue;
+	if (MAX_NUMNODES == 1)
+		init_sched_build_groups(sched_group_phys, cpu_possible_map,
+							&cpu_to_phys_group);
+	else {
+		/* Set up physical groups */
+		for (i = 0; i < MAX_NUMNODES; i++) {
+			cpumask_t nodemask = node_to_cpumask(i);
+
+			cpus_and(nodemask, nodemask, cpu_default_map);
+			if (cpus_empty(nodemask))
+				continue;
 
-		init_sched_build_groups(sched_group_phys, nodemask,
+			init_sched_build_groups(sched_group_phys, nodemask,
 						&cpu_to_phys_group);
+		}
 	}
 
 #ifdef CONFIG_NUMA