vmware balloon: clamp number of collected non-balloonable pages

commit 55adaa49 upstream.

Limit number of accumulated non-balloonable pages during inflation cycle,
otherwise there is a chance we will be spinning and growing the list
forever.  This happens during torture tests when balloon target changes
while we are in the middle of inflation cycle and monitor starts refusing
to lock pages (since they are not needed anymore).

Signed-off-by: Dmitry Torokhov <dtor@vmware.com>
Acked-by: Bhavesh Davda <bhavesh@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>