help with SMP debugging...task struct corruption

help with SMP debugging...task struct corruption

[Christopher Friesen]

I'm running a customized 2.6.10 and seeing some interesting behaviour. 
Based on some additional debugging that we added, the "p->signal" member 
is being set to NULL between the time we call spin_lock() and the time 
we return from it.

Anyone have any ideas what might be going on?  It seems to go away if we 
boot with only 1 cpu.  I assume that some other cpu already holds that 
lock and does something while holding it that causes the "p->signal" 
member to become NULL.


void release_task(struct task_struct * p)
{
	int zap_leader;
	task_t *leader;
	struct dentry *proc_dentry;

repeat:
	atomic_dec(&p->user->processes);
	spin_lock(&p->proc_lock);
	proc_dentry = proc_pid_unhash(p);



Thanks,

Chris

Re: help with SMP debugging...task struct corruption

[Arjan van de Ven]

On Tue, 2006-03-21 at 08:52 -0600, Christopher Friesen wrote:
> I'm running a customized 2.6.10 and seeing some interesting behaviour. 
> Based on some additional debugging that we added, the "p->signal" member 
> is being set to NULL between the time we call spin_lock() and the time 
> we return from it.

hmm odd... is your kernel patch available somewhere? Maybe there's a bug
in that (since this is not normal behavior at all)
(but then again 2.6.10 is *old* :)