[PATCH] [ARM] Do not call flush_cache_user_range with mmap_sem held
Russell King - ARM Linux
linux at arm.linux.org.uk
Tue May 4 03:40:57 EDT 2010
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.
I still do not think this is a good idea for the reasons I've already
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