[PATCH] [ARM] Do not call flush_cache_user_range with mmap_sem held

[Russell King - ARM Linux]

On Mon, May 03, 2010 at 09:07:03PM -0700, Dima Zavin wrote:
> >> The point of this code is to first validate that the region we're working
> >> on is valid.  As soon as we drop the lock, we lose the guarantee that
> >> the region is valid while we operate on it - indeed, the region could be
> >> unmapped and remapped by a different thread.
> >
> > So what if it was remapped? The worst case scenario in this case is
> > that we needlessly flush a region of memory, but its not "wrong". It
> > can't be any worse than just doing a full cache flush. If another
> > thread unmapped the region, then we should (and will) segfault the
> > flushing thread, which is the correct behavior IMHO.
> 
> ping.

I still do not think this is a good idea for the reasons I've already
mentioned.