Re: 2.6.10-mm1 hang

[Andrew Morton <akpm@osdl.org>]

Badari Pulavarty <pbadari@us.ibm.com> wrote:
>
> I was playing with kexec+kdump and ran into this on 2.6.10-mm1.
>  I have seen similar behaviour on 2.6.10. 
> 
>  I am using a 4-way P-III machine. I have a module which tries
>  gets same spinlock twice. When I try to "insmod" this module,
>  my system hangs. All my windows froze, no more new logins,
>  console froze, doesn't respond to sysrq. I wasn't expecting
>  a system hang. Why ? Ideas ?
> 

Maybe all the other CPUs are stuck trying to send an IPI to this one?  An
NMI watchdog trace would tell.

>  #include <linux/init.h>
>  #include <asm/uaccess.h>
>  #include <linux/spinlock.h>
>  spinlock_t mylock = SPIN_LOCK_UNLOCKED;
>  static int __init panic_init(void)
>  {
>          spin_lock_irq(&mylock);
>          spin_lock_irq(&mylock);
>         return 1;
>  }