[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/sched.c b/kernel/sched.c
index 5c848fd4e461..b946209d9c15 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5272,9 +5272,11 @@ static struct notifier_block __cpuinitdata migration_notifier = {
 int __init migration_init(void)
 {
         void *cpu = (void *)(long)smp_processor_id();
+        int err;
 
         /* Start one for the boot CPU: */
-        migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
+        err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
+        BUG_ON(err == NOTIFY_BAD);
         migration_call(&migration_notifier, CPU_ONLINE, cpu);
         register_cpu_notifier(&migration_notifier);