hibernation: freeze swap at hibernation
When taking a memory snapshot in hibernate_snapshot(), all (directly
called) memory allocations use GFP_ATOMIC. Hence swap misusage during
hibernation never occurs.
But from a pessimistic point of view, there is no guarantee that no page
allcation has __GFP_WAIT. It is better to have a global indication "we
enter hibernation, don't use swap!".
This patch tries to freeze new-swap-allocation during hibernation. (All
user processes are frozenm so swapin is not a concern).
This way, no updates will happen to swap_map[] between
hibernate_snapshot() and save_image(). Swap is thawed when swsusp_free()
is called. We can be assured that swap corruption will not occur.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Hugh Dickins <hughd@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Ondrej Zary <linux@rainbow-software.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/swap.h b/include/linux/swap.h
index ff4acea..91c9d3f 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -316,7 +316,6 @@
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);
@@ -333,6 +332,13 @@
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 *);