[BUG] arm64: an infinite loop in generic_perform_write()

[Christoph Hellwig]

On Thu, Jun 24, 2021 at 04:24:46AM +0100, Matthew Wilcox wrote:
> On Thu, Jun 24, 2021 at 11:10:41AM +0800, Chen Huang wrote:
> > In userspace, I perform such operation:
> > 
> >  	fd = open("/tmp/test", O_RDWR | O_SYNC);
> >         access_address = (char *)mmap(NULL, uio_size, PROT_READ, MAP_SHARED, uio_fd, 0);
> >         ret = write(fd, access_address + 2, sizeof(long));
> 
> ... you know that accessing this at unaligned offsets isn't going to
> work.  It's completely meaningless.  Why are you trying to do it?

We still should not cause an infinite loop in kernel space due to a
a userspace programmer error.