[PATCH] mm: improve function of sc->may_writepage

Make sc->may_writepage control the writeout behavior of shrink_list.

Remove the laptop_mode trick from shrink_list and instead set may_writepage
in try_to_free_pages properly.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>