BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff810af160>] sys_swapon+0x1f0/0xc60
PGD 1dc0b067 PUD 1dc09067 PMD 0
Oops: 0000 [#1] SMP
last sysfs file:
CPU 1
Modules linked in:
Pid: 562, comm: swapon Tainted: G        W  2.6.32-rc5-mm1_64 #867
RIP: 0010:[<ffffffff810af160>]  [<ffffffff810af160>] sys_swapon+0x1f0/0xc60
...

It is due to swap_info_struct->first_swap_extent.list not being
initialized. ->next is NULL in such a situation and
destroy_swap_extents fails to iterate over the list with the BUG
above.

Introduced by swap_info-include-first_swap_extent.patch. Revert the
INIT_LIST_HEAD move.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>