x86: fix stack overflow for large values of MAX_APICS

physid_mask_of_physid() causes a huge stack (12k) to be created if the
number of APICS is large. Replace physid_mask_of_physid() with a
new function that does not create large stacks. This is a problem only
on large x86_64 systems.

this paves the way to increase MAX_APICS.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Cc: linux-mm@kvack.org
Cc: mingo@elte.hu
Cc: tglx@linutronix.de
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 4 insertions, 5 deletions

diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c
index d5767cb19d56..3f13a1aa07cd 100644
--- a/arch/x86/kernel/apic_32.c
+++ b/arch/x86/kernel/apic_32.c
@@ -1269,7 +1269,7 @@ int __init APIC_init_uniprocessor(void)
 #ifdef CONFIG_CRASH_DUMP
         boot_cpu_physical_apicid = GET_APIC_ID(read_apic_id());
 #endif
-        phys_cpu_present_map = physid_mask_of_physid(boot_cpu_physical_apicid);
+        physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
 
         setup_local_APIC();
 
diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index 0633cfd0dc29..5e22f8d2d507 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -942,7 +942,7 @@ int __init APIC_init_uniprocessor(void)
 
         verify_local_APIC();
 
-        phys_cpu_present_map = physid_mask_of_physid(boot_cpu_physical_apicid);
+        physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
         apic_write(APIC_ID, SET_APIC_ID(boot_cpu_physical_apicid));
 
         setup_local_APIC();
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3e1cecedde42..664a5db36d40 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1091,10 +1091,9 @@ static __init void disable_smp(void)
         smpboot_clear_io_apic_irqs();
 #endif
         if (smp_found_config)
-                phys_cpu_present_map =
-                                physid_mask_of_physid(boot_cpu_physical_apicid);
+                physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
         else
-                phys_cpu_present_map = physid_mask_of_physid(0);
+                physid_set_mask_of_physid(0, &phys_cpu_present_map);
         map_cpu_to_logical_apicid();
         cpu_set(0, per_cpu(cpu_sibling_map, 0));
         cpu_set(0, per_cpu(cpu_core_map, 0));