swap: revert special hibernation allocation

Please revert 2.6.36-rc commit d2997b1042ec150616c1963b5e5e919ffd0b0ebf
"hibernation: freeze swap at hibernation".  It complicated matters by
adding a second swap allocation path, just for hibernation; without in any
way fixing the issue that it was intended to address - page reclaim after
fixing the hibernation image might free swap from a page already imaged as
swapcache, letting its swap be reallocated to store a different page of
the image: resulting in data corruption if the imaged page were freed as
clean then swapped back in.  Pages freed to si->swap_map were still in
danger of being reallocated by the alternative allocation path.

I guess it inadvertently fixed slow SSD swap allocation for hibernation,
as reported by Nigel Cunningham: by missing out the discards that occur on
the usual swap allocation path; but that was unintentional, and needs a
separate fix.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ondrej Zary <linux@rainbow-software.org>
Cc: Andrea Gelmini <andrea.gelmini@gmail.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nigel Cunningham <nigel@tuxonice.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 1 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 5e7edfb05e66..f6cd6faf84fd 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1086,7 +1086,6 @@ void swsusp_free(void)
         buffer = NULL;
         alloc_normal = 0;
         alloc_highmem = 0;
-        hibernation_thaw_swap();
 }
 
 /* Helper functions used for the shrinking of memory. */