Re: Problem with VMAP_STACK=y

From: JÃrg Otte
Date: Wed Oct 05 2016 - 11:21:54 EST


2016-10-05 11:04 GMT+02:00 Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>:
> Em Wed, 5 Oct 2016 09:50:42 +0200 (CEST)
> Jiri Kosina <jikos@xxxxxxxxxx> escreveu:
>
>> On Wed, 5 Oct 2016, Patrick Boettcher wrote:
>>
>> > > > Thanks for the quick response.
>> > > > Drivers are:
>> > > > dvb_core, dvb_usb, dbv_usb_cynergyT2
>> > >
>> > > This dbv_usb_cynergyT2 is not from Linus' tree, is it? I don't seem
>> > > to be able to find it, and the only google hit I am getting is your
>> > > very mail to LKML :)
>> >
>> > It's a typo, it should say dvb_usb_cinergyT2.
>>
>> Ah, thanks. Same issues there in
>>
>> cinergyt2_frontend_attach()
>> cinergyt2_rc_query()
>>
>> I think this would require more in-depth review of all the media drivers
>> and having all this fixed for 4.9. It should be pretty straightforward;
>> all the instances I've seen so far should be just straightforward
>> conversion to kmalloc() + kfree(), as the buffer is not being embedded in
>> any structure etc.
>
> What we're doing on most cases is to put a buffer (usually with 80
> chars for USB drivers) inside the "state" struct (on DVB drivers),
> in order to avoid doing kmalloc/kfree all the times. One such patch is
> changeset c4a98793a63c4.
>
> I'm enclosing a non-tested patch fixing it for the cinergyT2-core.c
> driver.
>
> Thanks,
> Mauro
>
> [PATCH] cinergyT2-core: don't do DMA on stack
>

Tried the cinergyT2 patch. No success. When I select a TV channel
just nothing happens. There are no error messages.

JÃrg