mm: fix pageref leak in do_swap_page()
mm: fix pageref leak in do_swap_page()

By the time the memory cgroup code is notified about a swapin we
already hold a reference on the fault page.

If the cgroup callback fails make sure to unlock AND release the page
reference which was taken by lookup_swap_cach(), or we leak the reference.

Signed-off-by: Johannes Weiner <331be22c6b63ca3e0a03d408c2d906b1b02cd5f2@cmpxchg.org>
Cc: Balbir Singh <65a1aed538f36fed73d8c45e9ddfc585ce9f4abf@linux.vnet.ibm.com>
Reviewed-by: Minchan Kim <12330474acf818c36105a159b1ab0efedce0665c@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <634f508bd7c47cf0ee4126243675c3e598920fbc@jp.fujitsu.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas