[PATCH] swsusp: avoid problems if there are too many pages to save

The following patch makes swsusp avoid problems during resume if there are
too many pages to save on suspend.  It adds a constant that allows us to
verify if we are going to save too many pages and implements the check
(this is done as early as we can tell that the check will trigger, which is
in swsusp_alloc()).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 8 insertions, 1 deletions

diff --git a/kernel/power/power.h b/kernel/power/power.h
index 9c9167d910dd..6748de23e83c 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -9,6 +9,9 @@
 #define SUSPEND_CONSOLE (MAX_NR_CONSOLES-1)
 #endif
 
+#define MAX_PBES        ((PAGE_SIZE - sizeof(struct new_utsname) \
+                        - 4 - 3*sizeof(unsigned long) - sizeof(int) \
+                        - sizeof(void *)) / sizeof(swp_entry_t))
 
 struct swsusp_info {
         struct new_utsname      uts;
@@ -18,7 +21,7 @@ struct swsusp_info {
         unsigned long           image_pages;
         unsigned long           pagedir_pages;
         suspend_pagedir_t       * suspend_pagedir;
-        swp_entry_t             pagedir[768];
+        swp_entry_t             pagedir[MAX_PBES];
 } __attribute__((aligned(PAGE_SIZE)));
 
 
diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
index 0dfb24948907..acf79ac1cb6d 100644
--- a/kernel/power/swsusp.c
+++ b/kernel/power/swsusp.c
@@ -931,6 +931,10 @@ static int swsusp_alloc(void)
         if (!enough_swap())
                 return -ENOSPC;
 
+        if (MAX_PBES < nr_copy_pages / PBES_PER_PAGE +
+            !!(nr_copy_pages % PBES_PER_PAGE))
+                return -ENOSPC;
+
         if (!(pagedir_save = alloc_pagedir(nr_copy_pages))) {
                 printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
                 return -ENOMEM;