Messages in this thread Patch in this message | | | From | KOSAKI Motohiro <> | Subject | [PATCH v3] x86-64, NUMA: fix fakenuma boot failure | Date | Fri, 15 Apr 2011 20:39:01 +0900 (JST) |
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Hello,
> Hello, > > On Thu, Apr 14, 2011 at 09:51:00AM +0900, KOSAKI Motohiro wrote: > > hmm... My carbon copy is not corrupted. Maybe crappy intermediate > > server override it ? > > Sorry about that. Problem was on my side. > > The patch itself looks good to me now, so, > > Acked-by: Tejun Heo <tj@kernel.org> > > but I have some nitpicky comments and it would be nice if you can > respin the patch with the suggested updates.
Reflected.
From 38f7fa6d48f2025bf620f1b8b27ccc7e0698d653 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 may panic due to devide by zero error depending on CPU configuration
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 divede by zero is caused following line. (ie group->cpu_power==0)
kernel/sched_fair.c::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 by commit e23bba6044 (x86-64, NUMA: Unify emulated distance mapping) because it changes cpu -> node mapping in the process of dropping fake_physnodes().
old) all cpus are assinged node 0 now) cpus are assigned round robin (the logic is implemented by numa_init_array())
Note: The change is heppen only if the system doesn't have neigher ACPI srat table nor AMD northbridge NUMA information.
Why round robin assignment doesn't work? Because init_numa_sched_groups_power() assumes all logical cpus in the same physical cpu share the same node (Then it only accounts for group_first_cpu()), and the simple round robin breaks the above assumption.
Thus, this patch implement to reassign node-id if buggy firmware or numa emulation makes wrong cpu node map. it enforce all logical cpus in the same physical cpu share the same node.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: 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..8ed8908 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 assumes all logical cpus in the same physical cpu + * share the same node. But, buggy ACPI 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
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