[PATCH] ARM: mm: avoid attempting to flush the gate_vma with VIVT caches

[Will Deacon]

On Thu, Jul 19, 2012 at 02:03:50PM +0100, Uros Bizjak wrote:
> On Thu, Jul 19, 2012 at 2:28 PM, Will Deacon <will.deacon at arm.com> wrote:
> 
> > On Mon, Jul 16, 2012 at 05:23:46PM +0100, Will Deacon wrote:
> >> The vivt_flush_cache_{range,page} functions check that the mm_struct
> >> of the VMA being flushed has been active on the current CPU before
> >> performing the cache maintenance.
> >>
> >> The gate_vma has a NULL mm_struct pointer and, as such, will cause a
> >> kernel fault if we try to flush it with the above operations. This
> >> happens during ELF core dumps, which include the gate_vma as it may be
> >> useful for debugging purposes.
> >>
> >> This patch adds checks to the VIVT cache flushing functions so that VMAs
> >> with a NULL mm_struct are ignored.
> >
> > Would one of you be able to test this patch please? I've not managed to
> > trigger the bug you reported on my boards, so it would be useful to know
> > whether or not this patch solves the problem for you.
> 
> Patched kernel works as expected. Also, backport to 3.4 (where
> original problem was triggered) works OK, so I'd suggest to backport
> this patch to 3.4.
> 
> Tested-by: Uros Bizjak <ubizjak at gmail.com>

Thanks Uros, I'll add that and CC stable on the patch too.

Will