aboutsummaryrefslogtreecommitdiffstats
path: root/mm
diff options
context:
space:
mode:
authorHugh Dickins <hughd@google.com>2010-09-09 16:38:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-09-09 18:57:25 -0700
commit910321ea817a202ff70fac666e37e2c8e2f88823 (patch)
treeaaead29e7797986e2b804746b565bb5d05117c54 /mm
parentac8456d6f9a3011c824176bd6084d39e5f70a382 (diff)
downloadmrst-s0i3-test-910321ea817a202ff70fac666e37e2c8e2f88823.tar.gz
mrst-s0i3-test-910321ea817a202ff70fac666e37e2c8e2f88823.tar.xz
mrst-s0i3-test-910321ea817a202ff70fac666e37e2c8e2f88823.zip
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/swapfile.c94
1 files changed, 22 insertions, 72 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 1f3f9c59a73..f08d165871b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -47,8 +47,6 @@ long nr_swap_pages;
long total_swap_pages;
static int least_priority;
-static bool swap_for_hibernation;
-
static const char Bad_file[] = "Bad swap file entry ";
static const char Unused_file[] = "Unused swap file entry ";
static const char Bad_offset[] = "Bad swap offset entry ";
@@ -453,8 +451,6 @@ swp_entry_t get_swap_page(void)
spin_lock(&swap_lock);
if (nr_swap_pages <= 0)
goto noswap;
- if (swap_for_hibernation)
- goto noswap;
nr_swap_pages--;
for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
@@ -487,6 +483,28 @@ noswap:
return (swp_entry_t) {0};
}
+/* The only caller of this function is now susupend routine */
+swp_entry_t get_swap_page_of_type(int type)
+{
+ struct swap_info_struct *si;
+ pgoff_t offset;
+
+ spin_lock(&swap_lock);
+ si = swap_info[type];
+ if (si && (si->flags & SWP_WRITEOK)) {
+ nr_swap_pages--;
+ /* This is called for allocating swap entry, not cache */
+ offset = scan_swap_map(si, 1);
+ if (offset) {
+ spin_unlock(&swap_lock);
+ return swp_entry(type, offset);
+ }
+ nr_swap_pages++;
+ }
+ spin_unlock(&swap_lock);
+ return (swp_entry_t) {0};
+}
+
static struct swap_info_struct *swap_info_get(swp_entry_t entry)
{
struct swap_info_struct *p;
@@ -746,74 +764,6 @@ int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep)
#endif
#ifdef CONFIG_HIBERNATION
-
-static pgoff_t hibernation_offset[MAX_SWAPFILES];
-/*
- * Once hibernation starts to use swap, we freeze swap_map[]. Otherwise,
- * saved swap_map[] image to the disk will be an incomplete because it's
- * changing without synchronization with hibernation snap shot.
- * At resume, we just make swap_for_hibernation=false. We can forget
- * used maps easily.
- */
-void hibernation_freeze_swap(void)
-{
- int i;
-
- spin_lock(&swap_lock);
-
- printk(KERN_INFO "PM: Freeze Swap\n");
- swap_for_hibernation = true;
- for (i = 0; i < MAX_SWAPFILES; i++)
- hibernation_offset[i] = 1;
- spin_unlock(&swap_lock);
-}
-
-void hibernation_thaw_swap(void)
-{
- spin_lock(&swap_lock);
- if (swap_for_hibernation) {
- printk(KERN_INFO "PM: Thaw Swap\n");
- swap_for_hibernation = false;
- }
- spin_unlock(&swap_lock);
-}
-
-/*
- * Because updateing swap_map[] can make not-saved-status-change,
- * we use our own easy allocator.
- * Please see kernel/power/swap.c, Used swaps are recorded into
- * RB-tree.
- */
-swp_entry_t get_swap_for_hibernation(int type)
-{
- pgoff_t off;
- swp_entry_t val = {0};
- struct swap_info_struct *si;
-
- spin_lock(&swap_lock);
-
- si = swap_info[type];
- if (!si || !(si->flags & SWP_WRITEOK))
- goto done;
-
- for (off = hibernation_offset[type]; off < si->max; ++off) {
- if (!si->swap_map[off])
- break;
- }
- if (off < si->max) {
- val = swp_entry(type, off);
- hibernation_offset[type] = off + 1;
- }
-done:
- spin_unlock(&swap_lock);
- return val;
-}
-
-void swap_free_for_hibernation(swp_entry_t ent)
-{
- /* Nothing to do */
-}
-
/*
* Find the swap type that corresponds to given device (if any).
*