[Nouveau] Is Nouveau really using the io_reserve_lru?

Koenig, Christian Christian.Koenig at amd.com
Fri Sep 27 12:19:56 UTC 2019

Am 26.09.19 um 23:44 schrieb Ben Skeggs:
> On Tue, 24 Sep 2019 at 22:19, Christian K├Ânig
> <ckoenig.leichtzumerken at gmail.com> wrote:
>> Hi guys,
>> while working through more old TTM functionality I stumbled over the
>> io_reserve_lru.
>> Basic idea is that when this flag is set the driver->io_mem_reserve()
>> callback can return -EAGAIN resulting in unmapping of other BOs.
>> But Nouveau doesn't seem to return -EAGAIN in the call path of
>> io_mem_reserve anywhere.
> I believe this is a bug in Nouveau.  We *should* be returning -EAGAIN
> if we fail to find space in BAR1 to map the BO into.

Yeah, thought that this is rather odd. But I can't fix it since I don't 
really know the code.

On the other hand do you have any objections that I move the remaining 
io_reserve_lru functionality into Nouveau then?

It's only used by this driver and since Thomas cleaned up the VM 
handling that shouldn't be a problem any more.


> Ben.
>> So is this unused or am I missing something?
>> Regards,
>> Christian.
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>> Nouveau at lists.freedesktop.org
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