Hi Geert,
On 2017-03-29 14:31:33 +0200, Geert Uytterhoeven wrote:
> Hi Niklas,
>
> On Wed, Mar 29, 2017 at 12:40 AM, Niklas Söderlund
> <niklas.soderlund+renesas@xxxxxxxxxxxx> wrote:
> > This fixes a race condition where the channel resources could be freed
> > before the ISR had finished running resulting in a NULL pointer
> > reference from the ISR.
> >
> > [ 167.148934] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> > [ 167.157051] pgd = ffff80003c641000
> > [ 167.160449] [00000000] *pgd=000000007c507003, *pud=000000007c4ff003, *pmd=0000000000000000
> > [ 167.168719] Internal error: Oops: 96000046 [#1] PREEMPT SMP
> > [ 167.174289] Modules linked in:
> > [ 167.177348] CPU: 3 PID: 10547 Comm: dma_ioctl Not tainted 4.11.0-rc1-00001-g8d92afddc2f6633a #73
> > [ 167.186131] Hardware name: Renesas Salvator-X board based on r8a7795 (DT)
> > [ 167.192917] task: ffff80003a411a00 task.stack: ffff80003bcd4000
> > [ 167.198850] PC is at rcar_dmac_chan_prep_sg+0xe0/0x400
> > [ 167.203985] LR is at rcar_dmac_chan_prep_sg+0x48/0x400
>
> Do you have a test case to trigger this?
Yes I have a testcase, it's rather complex and involves both a kernel
module and a userspaces application to stress the rcar-dmac. I'm
checking if I can share this publicly or not, please hold :-)
>
> Thanks!
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
--
Regards,
Niklas Söderlund
