x86: leave initial __cpu_pda array in place until cpus are booted

Ingo Molnar wrote:
...
> they crashed after about 3 randconfig iterations with:
>
>   early res: 4 [8000-afff] PGTABLE
>   early res: 5 [b000-b87f] MEMNODEMAP
> PANIC: early exception 0e rip 10:ffffffff8077a150 error 2 cr2 37
> Pid: 0, comm: swapper Not tainted 2.6.25-sched-devel.git-x86-latest.git #14
>
> Call Trace:
>  [<ffffffff81466196>] early_idt_handler+0x56/0x6a
>  [<ffffffff8077a150>] ? numa_set_node+0x30/0x60
>  [<ffffffff8077a129>] ? numa_set_node+0x9/0x60
>  [<ffffffff8147a543>] numa_init_array+0x93/0xf0
>  [<ffffffff8147b039>] acpi_scan_nodes+0x3b9/0x3f0
>  [<ffffffff8147a496>] numa_initmem_init+0x136/0x150
>  [<ffffffff8146da5f>] setup_arch+0x48f/0x700
>  [<ffffffff802566ea>] ? clockevents_register_notifier+0x3a/0x50
>  [<ffffffff81466a87>] start_kernel+0xd7/0x440
>  [<ffffffff81466422>] x86_64_start_kernel+0x222/0x280
...
Here's the fixup...  This one should follow the previous patches.

Thanks,
Mike
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/head64.c

@@ -29,17 +29,13 @@
 static struct x8664_pda _boot_cpu_pda __read_mostly;
 
 #ifdef CONFIG_SMP
-#ifdef CONFIG_DEBUG_PER_CPU_MAPS
 /*
- * We install an empty cpu_pda pointer table to trap references before
- * the actual cpu_pda pointer table is created in setup_cpu_pda_map().
+ * We install an empty cpu_pda pointer table to indicate to early users
+ * (numa_set_node) that the cpu_pda pointer table for cpus other than
+ * the boot cpu is not yet setup.
  */
 static struct x8664_pda *__cpu_pda[NR_CPUS] __initdata;
 #else
-static struct x8664_pda *__cpu_pda[1] __read_mostly;
-#endif
-
-#else /* !CONFIG_SMP (NR_CPUS will be 1) */
 static struct x8664_pda *__cpu_pda[NR_CPUS] __read_mostly;
 #endif