kernel crash: solved (Was: copy_process && utrace_init_task)

[Oleg Nesterov]

On 11/17, Oleg Nesterov wrote:
>
> On 11/16, Oleg Nesterov wrote:
> >
> > On 11/16, Oleg Nesterov wrote:
> > >
> > > And I didn't check "make xcheck", I guess it still crashes the kernel.
> >
> > Yes it does. I am almost sure the bug should be trivial, but
> > somehow can't find find it.
>
> Found the trivial but nasty problem.
>
> And! While this bug could perfectly explain the crash, it doesn't.
> I appiled this patch
>
> 	--- UTRACE-PTRACE/kernel/fork.c~XXX_CRASH	2009-11-16 20:26:23.000000000 +0100
> 	+++ UTRACE-PTRACE/kernel/fork.c	2009-11-17 20:33:50.000000000 +0100
> 	@@ -1019,6 +1019,7 @@ static struct task_struct *copy_process(
> 		if (!p)
> 			goto fork_out;
> 	 
> 	+p->utrace = NULL;
> 		ftrace_graph_init_task(p);
> 	 
> 		rt_mutex_init_task(p);
>
> but "make xcheck" still crashes. Still investigating.

Damn!!!

It works, the kernel does NOT crash.

(by mistake, I copied bzImage to the wrong location, iow I tested
 the kernel without the patch above).

Oleg.