On Thu, May 17, 2007 at 09:38:59PM +1000, Keith Owens wrote: > Robin Holt (on Thu, 17 May 2007 06:16:52 -0500) wrote: ... > AFAICT there is no lock on struct task_struct p that stops it being > scheduled to run after you test if it is running. proc_task_lookup() > only does get_task_struct() which prevents the task from being deleted, > it does not prevent the task from being scheduled while you are looking > at it. > > So even with that check, it can race between not running and running > while you do the unwind, and still get the MCA. I realized the problem, but don't see an easy fix. I think the hope is we would be far enough back in the call trace so that portion of the stack would be constant. To me, this still seems like a reasonable check. Do you object to this patch or are you just pointing out the hole. I see the other architectures have the same problem. Would you suggest repeating the check before each call to unw_unwind()? Thanks, Robin - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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