swap: warn when a swap area overflows the maximum size

[karo-tx-linux.git] / mm / swapfile.c

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6cf2e60983b7c36c5dea0b745e6aadd907c01532..b5212eea6c3cc431dd97ec7271957e798044a858 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1926,6 +1926,7 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
        int i;
        unsigned long maxpages;
        unsigned long swapfilepages;
+       unsigned long last_page;
 
        if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
                printk(KERN_ERR "Unable to find swap-space signature\n");
@@ -1968,8 +1969,15 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
         */
        maxpages = swp_offset(pte_to_swp_entry(
                        swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
-       if (maxpages > swap_header->info.last_page) {
-               maxpages = swap_header->info.last_page + 1;
+       last_page = swap_header->info.last_page;
+       if (last_page > maxpages) {
+               printk(KERN_WARNING
+                       "Truncating oversized swap area, only using %luk out of %luk\n",
+                       maxpages << (PAGE_SHIFT - 10),
+                       last_page << (PAGE_SHIFT - 10));
+       }
+       if (maxpages > last_page) {
+               maxpages = last_page + 1;
                /* p->max is an unsigned int: don't overflow it */
                if ((unsigned int)maxpages == 0)
                        maxpages = UINT_MAX;