Re: Problem with VMAP_STACK=y
From: Jiri Kosina
Date: Tue Oct 04 2016 - 09:28:01 EST
On Tue, 4 Oct 2016, JÃrg Otte wrote:
> With kernel 4.8.0-01558-g21f54dd I get thousands of
> "dvb-usb: bulk message failed: -11 (1/0)"
> messages in the logs and the DVB adapter is not working.
> It tourned out the new config option VMAP_STACK=y (which is the default)
> is the culprit.
> No problems for me with VMAP_STACK=n.
I'd guess that this is EAGAIN coming from usb_hcd_map_urb_for_dma() as the
DVB driver is trying to perform on-stack DMA.
Not really knowing which driver exactly you're using, I quickly skimmed
through DVB sources, and it turns out this indeed seems to be rather
common antipattern, and it should be fixed nevertheless. See
Adding relevant CCs.