ARM64: kernel panics in DABT in sys_msync path

[Will Deacon]

Yury, Richard,

On Tue, Sep 26, 2017 at 08:23:35AM -0600, Ruigrok, Richard wrote:
> On 9/26/2017 4:23 AM, Will Deacon wrote:
> > On Mon, Sep 25, 2017 at 01:54:57PM -0600, Ruigrok, Richard wrote:
> >> I also found this issue with kernels from 4.11 through 4.13.  In my tests, I
> >> found that it reproduces only with 4K page and Transparent Huge Pages. With 64K
> >> page I was not able to reproduce. RH also reported it here: https://
> >> bugzilla.redhat.com/show_bug.cgi?id=1491504 Linaro reported on the RPK kernel
> >> (4.12) on Centriq2400 and ThunderX
> >>  
> >>
> >> https://bugs.linaro.org/show_bug.cgi?id=3191
> >>
> >> https://bugs.linaro.org/show_bug.cgi?id=3068.
> > These two aren't the same bug (that's a forward progress issue that we're
> > currently working on). I don't have permission to look at the redhat one,
> > but is it just an RCU stall or actually the Oops reported by Yury?
> >
> >> I was able to bisect down to a specific commit.
> > I think we're chasing two different things here, so not sure I trust the
> > bisect!
> >
> The RCU stall is side effect.  The issue I'm seeing has the same stack
> trace and same stimulus (rwtest).  Following are the details.

FWIW, I think I've worked out what's going on here and I should have a patch
tomorrow.

Will