consistent_free re-revisited

[Benjamin Herrenschmidt]

>> That's the least of our worries - the current consistent_alloc() is
>> badly broken.  It breaks the DMA-mapping.txt rules, because it can't
>> safely be called from interrupt context.  I think we need generic
>> changes (gfp masks to various functions) to fix this sanely.
>
>IIRC, to fix the interrupt context bit, we need something like the
>following, which was Paul's idea, and he said he would talk to Dave M.
>about it.  Did anything ever happen there?

I tend to hate anything that relies on in_interrupt() as they
are other contexts that will have in_interrupt() cleared but still
have the same limitations. Typically, anything on the VM path must
do either GFP_ATOMIC or GFP_NOIO allocations, wether it's running
at interrupt time or not.

Ben.


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