[xfs-masters] Re: freeze vs freezer

[Pavel Machek <pavel@xxxxxxx>]

Hi!

(replying to *very* old mail).

>>>> We wait until they can continue.
>>>
>>> So if I have a process blocked on an unavilable NFS mount, I can't
>>> suspend?
>>
>> That's correct, you can't.
>>
>> [And I know what you're going to say. ;-)]
>
> Why exactly does suspend/hibernation depend on "TASK_INTERRUPTIBLE" instead 
> of a zero preempt_count()?  Really what we should do is just iterate over 
> all of the actual physical devices and tell each one "Block new IO requests 
> preemptably, finish pending DMA, put the hardware in low-power mode, and 
> prepare for suspend/hibernate".  As long as each driver knows how to do 
> those simple things we can have an entirely consistent kernel image for 
> both suspend and for hibernation.

Patch would be welcome, actually. It turns out blocking new
IO-requests is not completely trivial.
                                                                        Pavel
-- 
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