[PATCH v2] x86-64, NUMA: fix fakenuma boot failure

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

Hi

> Hello,
> 
> On Wed, Apr 13, 2011 at 04:02:43PM +0900, KOSAKI Motohiro wrote:
> > Your patch have two mistake.
> > 
> >  1) link_thread_siblings() is for HT
> >     set_cpu_sibling_map() has another sibling calculations.
> >  2) numa_set_node() is not enough. scheduler is using node_to_cpumask_map[] too.
> 
> Thanks for seeing this through but your patch is badly whitespace
> broken.  Can you please check your mail setup and repost?  Also, some
> comments below.

hmm...
My carbon copy is not corrupted. Maybe crappy intermediate server override it?


> > btw, Please see cpu_coregroup_mask(). its return value depend on 
> > sched_mc_power_savings and sched_smt_power_savings. then, we need to care
> > both cpu_core_mask and cpu_llc_shared_mask. I think.
> 
> Hmmmm....
> 
> > +static void __cpuinit node_cpumap_same_phys(int cpu1, int cpu2)
> 
> What does the "phys" mean?  Maybe something like
> check_cpu_siblings_on_same_node() is a better name?

ok, will fix.


> 
> > +	/*
> > +	 * Our CPU scheduler assume all cpus in the same physical cpu package
> > +	 * are assigned the same node. But, Buggy ACPI table or NUMA emulation
> > +	 * might assigne them to different node. Fix it.
> 		typo

Grr. thank you.

> 
> > +	*/
> > +	if (node1 != node2) {
> > +		pr_warning("CPU %d in node %d and CPU %d in node %d are in the same physical CPU. forcing same node %d\n",
> > +			   cpu1, node1, cpu2, node2, node2);
> > +
> > +		numa_set_node(cpu1, node2);
> > +		cpumask_set_cpu(cpu1, node_to_cpumask_map[node2]);
> > +		cpumask_clear_cpu(cpu1, node_to_cpumask_map[node1]);
> 
> Maybe what you want is the following?
> 
> 	numa_remove_cpu(cpu1);
> 	numa_set_node(cpu1, node2)
> 	numa_add_cpu(cpu1)

Right. That's better.


>From 1b7868de51941f39699c08f0d6ab429cd9db15bf Mon Sep 17 00:00:00 2001
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date: Wed, 13 Apr 2011 15:47:12 +0900
Subject: [PATCH] x86-64, NUMA: fix fakenuma boot failure

Currently, numa=fake boot parameter is broken. If it's used, kernel
doesn't boot and makes panic by zero divide error.

Call Trace:
 [<ffffffff8104ad4c>] find_busiest_group+0x38c/0xd30
 [<ffffffff81086aff>] ? local_clock+0x6f/0x80
 [<ffffffff81050533>] load_balance+0xa3/0x600
 [<ffffffff81050f53>] idle_balance+0xf3/0x180
 [<ffffffff81550092>] schedule+0x722/0x7d0
 [<ffffffff81550538>] ? wait_for_common+0x128/0x190
 [<ffffffff81550a65>] schedule_timeout+0x265/0x320
 [<ffffffff81095815>] ? lock_release_holdtime+0x35/0x1a0
 [<ffffffff81550538>] ? wait_for_common+0x128/0x190
 [<ffffffff8109bb6c>] ? __lock_release+0x9c/0x1d0
 [<ffffffff815534e0>] ? _raw_spin_unlock_irq+0x30/0x40
 [<ffffffff815534e0>] ? _raw_spin_unlock_irq+0x30/0x40
 [<ffffffff81550540>] wait_for_common+0x130/0x190
 [<ffffffff81051920>] ? try_to_wake_up+0x510/0x510
 [<ffffffff8155067d>] wait_for_completion+0x1d/0x20
 [<ffffffff8107f36c>] kthread_create_on_node+0xac/0x150
 [<ffffffff81077bb0>] ? process_scheduled_works+0x40/0x40
 [<ffffffff8155045f>] ? wait_for_common+0x4f/0x190
 [<ffffffff8107a283>] __alloc_workqueue_key+0x1a3/0x590
 [<ffffffff81e0cce2>] cpuset_init_smp+0x6b/0x7b
 [<ffffffff81df3d07>] kernel_init+0xc3/0x182
 [<ffffffff8155d5e4>] kernel_thread_helper+0x4/0x10
 [<ffffffff81553cd4>] ? retint_restore_args+0x13/0x13
 [<ffffffff81df3c44>] ? start_kernel+0x400/0x400
 [<ffffffff8155d5e0>] ? gs_change+0x13/0x13

The zero divede is caused following line. (ie group->cpu_power==0)

update_sg_lb_stats()
        /* Adjust by relative CPU power of the group */
        sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) /
group->cpu_power;

This is regression  since commit e23bba6044 (x86-64, NUMA: Unify
emulated distance mapping). Because It drop fake_physnodes() and
then cpu-node mapping was changed.

old) all cpus are assinged node 0
now) cpus are assigned round robin
     (the logic is implemented by numa_init_array())

Why round robin assignment doesn't work? Because init_numa_sched_groups_power()
assume all logical cpus in the same physical cpu are assigned the same node.
(Then it only account group_first_cpu()). But the simple round robin
broke the above assumption.

Thus, this patch implement to reassigne node-id if buggy firmware or numa
emulation makes wrong cpu node map.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Shaohui Zheng <shaohui.zheng@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/kernel/smpboot.c |   23 +++++++++++++++++++++++
 1 files changed, 23 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index c2871d3..78c422d 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -312,6 +312,26 @@ void __cpuinit smp_store_cpu_info(int id)
 		identify_secondary_cpu(c);
 }
 
+static void __cpuinit check_cpu_siblings_on_same_node(int cpu1, int cpu2)
+{
+	int node1 = early_cpu_to_node(cpu1);
+	int node2 = early_cpu_to_node(cpu2);
+
+	/*
+	 * Our CPU scheduler assume all logical cpus in the same physical cpu
+	 * package are assigned the same node. But, Buggy ACPI table or NUMA
+	 * emulation might assign them to different node. Fix it.
+	*/
+	if (node1 != node2) {
+		pr_warning("CPU %d in node %d and CPU %d in node %d are in the same physical CPU. forcing same node %d\n",
+			   cpu1, node1, cpu2, node2, node2);
+
+		numa_remove_cpu(cpu1);
+		numa_set_node(cpu1, node2);
+		numa_add_cpu(cpu1);
+	}
+}
+
 static void __cpuinit link_thread_siblings(int cpu1, int cpu2)
 {
 	cpumask_set_cpu(cpu1, cpu_sibling_mask(cpu2));
@@ -320,6 +340,7 @@ static void __cpuinit link_thread_siblings(int cpu1, int cpu2)
 	cpumask_set_cpu(cpu2, cpu_core_mask(cpu1));
 	cpumask_set_cpu(cpu1, cpu_llc_shared_mask(cpu2));
 	cpumask_set_cpu(cpu2, cpu_llc_shared_mask(cpu1));
+	check_cpu_siblings_on_same_node(cpu1, cpu2);
 }
 
 
@@ -361,10 +382,12 @@ void __cpuinit set_cpu_sibling_map(int cpu)
 		    per_cpu(cpu_llc_id, cpu) == per_cpu(cpu_llc_id, i)) {
 			cpumask_set_cpu(i, cpu_llc_shared_mask(cpu));
 			cpumask_set_cpu(cpu, cpu_llc_shared_mask(i));
+			check_cpu_siblings_on_same_node(cpu, i);
 		}
 		if (c->phys_proc_id == cpu_data(i).phys_proc_id) {
 			cpumask_set_cpu(i, cpu_core_mask(cpu));
 			cpumask_set_cpu(cpu, cpu_core_mask(i));
+			check_cpu_siblings_on_same_node(cpu, i);
 			/*
 			 *  Does this new cpu bringup a new core?
 			 */
-- 
1.7.3.1