Re: [PATCH 4/5] x86: Add config variables for SMP_MAX


* Ingo Molnar <mingo@xxxxxxx> wrote:

NR_CPUS: max limit now 4096
NODES_SHIFT: max limit now 9
THREAD_ORDER: max limit now 3
X86_SMP_MAX: say Y to enable possible cpus == NR_CPUS

Signed-off-by: Mike Travis <travis@xxxxxxx>

i've bisected a boot failure down to this patch (sans the THREAD_ORDER
bits): it causes an instant reboot of the 64-bit kernel upon bootup.
Failing config attached.

and then it crashes with:

[ 0.000000] Bootmem setup node 0 0000000000000000-000000003fff0000
[ 0.000000] KERN_NOTICE cpu_to_node(0): usage too early!
PANIC: early exception 06 rip 10:ffffffff81f77f30 error 0 cr2 f06f53
[ 0.000000] Pid: 0, comm: swapper Not tainted 2.6.24-rc8 #422
[ 0.000000]
[ 0.000000] Call Trace:
[ 0.000000] [<ffffffff81f76b4a>] ? setup_node_bootmem+0x1a0/0x1b8
[ 0.000000] [<ffffffff81f77f30>] ? acpi_scan_nodes+0x204/0x255
[ 0.000000] [<ffffffff81f77f30>] ? acpi_scan_nodes+0x204/0x255
[ 0.000000] [<ffffffff81f77103>] ? numa_initmem_init+0x343/0x471

moral: PLEASE do not use BUG() on in early init code, unless absolutely
necessary.

Ingo

---
include/asm-x86/topology.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

Index: linux/include/asm-x86/topology.h
===================================================================
--- linux.orig/include/asm-x86/topology.h
+++ linux/include/asm-x86/topology.h
@@ -70,10 +70,11 @@ static inline int cpu_to_node(int cpu)
if(x86_cpu_to_node_map_early_ptr) {
printk("KERN_NOTICE cpu_to_node(%d): usage too early!\n",
(int)cpu);
- BUG();
+ dump_stack();
+ return 0;
}
#endif
- if(per_cpu_offset(cpu))
+ if (per_cpu_offset(cpu))
return per_cpu(x86_cpu_to_node_map, cpu);
else
return NUMA_NO_NODE;
--
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