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Message-ID: <alpine.LSU.2.00.1009060104410.13600@sister.anvils>
Date: Mon, 6 Sep 2010 01:10:55 -0700 (PDT)
From: Hugh Dickins <hughd@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Ondrej Zary <linux@...nbow-software.org>,
Andrea Gelmini <andrea.gelmini@...il.com>,
Balbir Singh <balbir@...ibm.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Nigel Cunningham <nigel@...onice.net>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] 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@...gle.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Ondrej Zary <linux@...nbow-software.org>
Cc: Andrea Gelmini <andrea.gelmini@...il.com>
Cc: Balbir Singh <balbir@...ibm.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Nigel Cunningham <nigel@...onice.net>
---
include/linux/swap.h | 8 ---
kernel/power/hibernate.c | 1
kernel/power/snapshot.c | 1
kernel/power/swap.c | 6 +-
mm/swapfile.c | 94 ++++++++-----------------------------
5 files changed, 26 insertions(+), 84 deletions(-)
--- 2.6.36-rc3/include/linux/swap.h 2010-08-16 00:17:59.000000000 -0700
+++ swap1/include/linux/swap.h 2010-09-05 22:37:07.000000000 -0700
@@ -315,6 +315,7 @@ extern long nr_swap_pages;
extern long total_swap_pages;
extern void si_swapinfo(struct sysinfo *);
extern swp_entry_t get_swap_page(void);
+extern swp_entry_t get_swap_page_of_type(int);
extern int valid_swaphandles(swp_entry_t, unsigned long *);
extern int add_swap_count_continuation(swp_entry_t, gfp_t);
extern void swap_shmem_alloc(swp_entry_t);
@@ -331,13 +332,6 @@ extern int reuse_swap_page(struct page *
extern int try_to_free_swap(struct page *);
struct backing_dev_info;
-#ifdef CONFIG_HIBERNATION
-void hibernation_freeze_swap(void);
-void hibernation_thaw_swap(void);
-swp_entry_t get_swap_for_hibernation(int type);
-void swap_free_for_hibernation(swp_entry_t val);
-#endif
-
/* linux/mm/thrash.c */
extern struct mm_struct *swap_token_mm;
extern void grab_swap_token(struct mm_struct *);
--- 2.6.36-rc3/kernel/power/hibernate.c 2010-08-16 00:18:00.000000000 -0700
+++ swap1/kernel/power/hibernate.c 2010-09-05 22:37:07.000000000 -0700
@@ -338,7 +338,6 @@ int hibernation_snapshot(int platform_mo
goto Close;
suspend_console();
- hibernation_freeze_swap();
saved_mask = clear_gfp_allowed_mask(GFP_IOFS);
error = dpm_suspend_start(PMSG_FREEZE);
if (error)
--- 2.6.36-rc3/kernel/power/snapshot.c 2010-08-16 00:18:00.000000000 -0700
+++ swap1/kernel/power/snapshot.c 2010-09-05 22:37:07.000000000 -0700
@@ -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. */
--- 2.6.36-rc3/kernel/power/swap.c 2010-08-16 00:18:00.000000000 -0700
+++ swap1/kernel/power/swap.c 2010-09-05 22:37:07.000000000 -0700
@@ -136,10 +136,10 @@ sector_t alloc_swapdev_block(int swap)
{
unsigned long offset;
- offset = swp_offset(get_swap_for_hibernation(swap));
+ offset = swp_offset(get_swap_page_of_type(swap));
if (offset) {
if (swsusp_extents_insert(offset))
- swap_free_for_hibernation(swp_entry(swap, offset));
+ swap_free(swp_entry(swap, offset));
else
return swapdev_block(swap, offset);
}
@@ -163,7 +163,7 @@ void free_all_swap_pages(int swap)
ext = container_of(node, struct swsusp_extent, node);
rb_erase(node, &swsusp_extents);
for (offset = ext->start; offset <= ext->end; offset++)
- swap_free_for_hibernation(swp_entry(swap, offset));
+ swap_free(swp_entry(swap, offset));
kfree(ext);
}
--- 2.6.36-rc3/mm/swapfile.c 2010-08-16 00:18:01.000000000 -0700
+++ swap1/mm/swapfile.c 2010-09-05 22:37:07.000000000 -0700
@@ -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
#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).
*
--
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