[PATCH] cpu: mark cpu_possible_mask as __ro_after_init

[Alexey Dobriyan <adobriyan@gmail.com>]

cpu_possible_mask is by definition "cpus which could be hotplugged
without reboot" -- property which is fixed after kernel enumerates
motheboard capabilities and hardware configuration.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

 kernel/cpu.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -3107,10 +3107,10 @@ const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 EXPORT_SYMBOL(cpu_all_bits);
 
 #ifdef CONFIG_INIT_ALL_POSSIBLE
-struct cpumask __cpu_possible_mask __read_mostly
+struct cpumask __cpu_possible_mask __ro_after_init;
 	= {CPU_BITS_ALL};
 #else
-struct cpumask __cpu_possible_mask __read_mostly;
+struct cpumask __cpu_possible_mask __ro_after_init;
 #endif
 EXPORT_SYMBOL(__cpu_possible_mask);