[PATCH] check return value of cpu_callback

Spawing ksoftirqd, migration, or watchdog, and calling init_timers_cpu()
may fail with small memory.  If it happens in initcalls, kernel NULL
pointer dereference happens later.  This patch makes crash happen
immediately in such cases.  It seems a bit better than getting kernel NULL
pointer dereference later.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 3789ca98197c..bf25015dce16 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -612,7 +612,9 @@ static struct notifier_block __cpuinitdata cpu_nfb = {
 __init int spawn_ksoftirqd(void)
 {
         void *cpu = (void *)(long)smp_processor_id();
-        cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
+        int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
+
+        BUG_ON(err == NOTIFY_BAD);
         cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
         register_cpu_notifier(&cpu_nfb);
         return 0;