Re: CVS commit: src/sys/arch/xen/xen

[Adam Hamsik <haaaad%gmail.com@localhost>]

On Apr,Monday 18 2011, at 10:26 AM, Mindaugas Rasiukevicius wrote:

> "Cherry G. Mathew" <cherry.g.mathew%gmail.com@localhost> wrote:
>>>>> On Mon, Apr 18, 2011 at 03:04:32AM +0000, Mindaugas Rasiukevicius
>>>>> wrote:
>>>>>> Module Name:        src
>>>>>> Committed By:       rmind
>>>>>> Date:               Mon Apr 18 03:04:31 UTC 2011
>>>>>> 
>>>>>> Modified Files:
>>>>>>     src/sys/arch/xen/xen: balloon.c
>>>>>> 
>>>>>> Log Message:
>>>>>> balloon_xenbus_attach: use KM_SLEEP for allocation.
>>>>>> 
>>>>>> Note: please do not use KM_NOSLEEP.
>>>>> 
>>>>> And, according to yamt@, KM_SLEEP can fail in the current design...
>>>> 
>>>> IIRC yamt@ fixed it a year or few ago.
>>>> 
>>> 
>>> And in the more specific immediate context:
>>> http://mail-index.netbsd.org/port-xen/2011/04/07/msg006613.html
>>> 
>>> 
>> 
>> Hi,
>> 
>> PS: Can you please revert ? Unless it's breaking anything else, or you
>> have a fix for the problem mentioned in the thread above, ie;
> 
> Change is for balloon_xenbus_attach(), which is irrelevant to the issue
> described in that email.
> 
> Are you aware that KM_NOSLEEP might fail not only because there is no
> memory (or KVA) available, though?

I had several problems with memory hungry zfs, where allocation failed just
because some lock in uvm was hold when KM_NOSLEEP allocation was issued. 
We should avoid of using KM_NOSLEEP whenever is it possible.

Regards

Adam.