[Fedora-xen] Re: [Xen-ia64-devel] Fedora-xen-ia64 test status

[Rik van Riel]

Akio Takebe wrote:
> Hi, Dave and Xen people
> 
>>> Do we need CONFIG_DEBUG_SPINLOCK_SLEEP?
>> Yes, because it highlights bugs like the above.
>>
>>> If we need CONFIG_DEBUG_SPINLOCK_SLEEP, we must modify __might_sleep().
>> No, you must fix ia64 so that it doesn't call down_read with
>> interrupts disabled.
> OK, but I think this is not bug.
> I thik this messages are caused by domain scheduler of Xen.
> Time slice of domain schedule is longer than HZ. (probably)
> Am I right, xen people?

Nope, __might_sleep() is simply called from code paths that
might sleep.  The only reason there's timer code in __might_sleep()
is for printk rate limiting.

You can not call down_read() with interrupts disabled, because
the mutex code might need to sleep.  The code needs to be fixed.

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan