mm: account skipped entries to avoid looping in find_get_pages
The found entries by find_get_pages() could be all swap entries. In
this case we skip the entries, but make sure the skipped entries are
accounted, so we don't keep looping.
Using nr_found > nr_skip to simplify code as suggested by Eric.
Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>