[RFC PATCH] smpboot: Check for successfull allocation of cpumask vars

[Pranith Kumar <bobby.prani@gmail.com>]

zalloc_cpumask_var() can return 0 on allocation failure when
CONFIG_CPUMASK_OFFSTACK is set. Check for the return value and WARN() on failure
of an allocation in such cases.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
---
 arch/x86/kernel/smpboot.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 7a8f584..9b1df21 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1083,6 +1083,7 @@ static void __init smp_cpu_index_default(void)
 void __init native_smp_prepare_cpus(unsigned int max_cpus)
 {
 	unsigned int i;
+	bool ret = true;
 
 	preempt_disable();
 	smp_cpu_index_default();
@@ -1096,9 +1097,12 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 
 	current_thread_info()->cpu = 0;  /* needed? */
 	for_each_possible_cpu(i) {
-		zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
-		zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
-		zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
+		ret &= zalloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
+		ret &= zalloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
+		ret &= zalloc_cpumask_var(&per_cpu(cpu_llc_shared_map, i), GFP_KERNEL);
+
+		if (WARN(!ret, "cpumask alloc for cpu %d failed!", i))
+			break;
 	}
 	set_cpu_sibling_map(0);
 
-- 
1.9.1