xen/balloon: set ballooned out pages as invalid in p2m

[cascardo/linux.git] / drivers / xen / balloon.c

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 61a6ac8..5c660c7 100644 (file)
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -426,20 +426,18 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
                 * p2m are consistent.
                 */
                if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-                       unsigned long p;
-                       struct page   *scratch_page = get_balloon_scratch_page();
-
                        if (!PageHighMem(page)) {
+                               struct page *scratch_page = get_balloon_scratch_page();
+
                                ret = HYPERVISOR_update_va_mapping(
                                                (unsigned long)__va(pfn << PAGE_SHIFT),
                                                pfn_pte(page_to_pfn(scratch_page),
                                                        PAGE_KERNEL_RO), 0);
                                BUG_ON(ret);
-                       }
-                       p = page_to_pfn(scratch_page);
-                       __set_phys_to_machine(pfn, pfn_to_mfn(p));
 
-                       put_balloon_scratch_page();
+                               put_balloon_scratch_page();
+                       }
+                       __set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
                }
 #endif
 
@@ -604,19 +602,29 @@ static void __init balloon_add_region(unsigned long start_pfn,
        }
 }
 
+static int alloc_balloon_scratch_page(int cpu)
+{
+       if (per_cpu(balloon_scratch_page, cpu) != NULL)
+               return 0;
+
+       per_cpu(balloon_scratch_page, cpu) = alloc_page(GFP_KERNEL);
+       if (per_cpu(balloon_scratch_page, cpu) == NULL) {
+               pr_warn("Failed to allocate balloon_scratch_page for cpu %d\n", cpu);
+               return -ENOMEM;
+       }
+
+       return 0;
+}
+
+
 static int balloon_cpu_notify(struct notifier_block *self,
                                    unsigned long action, void *hcpu)
 {
        int cpu = (long)hcpu;
        switch (action) {
        case CPU_UP_PREPARE:
-               if (per_cpu(balloon_scratch_page, cpu) != NULL)
-                       break;
-               per_cpu(balloon_scratch_page, cpu) = alloc_page(GFP_KERNEL);
-               if (per_cpu(balloon_scratch_page, cpu) == NULL) {
-                       pr_warn("Failed to allocate balloon_scratch_page for cpu %d\n", cpu);
+               if (alloc_balloon_scratch_page(cpu))
                        return NOTIFY_BAD;
-               }
                break;
        default:
                break;
@@ -636,15 +644,17 @@ static int __init balloon_init(void)
                return -ENODEV;
 
        if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-               for_each_online_cpu(cpu)
-               {
-                       per_cpu(balloon_scratch_page, cpu) = alloc_page(GFP_KERNEL);
-                       if (per_cpu(balloon_scratch_page, cpu) == NULL) {
-                               pr_warn("Failed to allocate balloon_scratch_page for cpu %d\n", cpu);
+               register_cpu_notifier(&balloon_cpu_notifier);
+
+               get_online_cpus();
+               for_each_online_cpu(cpu) {
+                       if (alloc_balloon_scratch_page(cpu)) {
+                               put_online_cpus();
+                               unregister_cpu_notifier(&balloon_cpu_notifier);
                                return -ENOMEM;
                        }
                }
-               register_cpu_notifier(&balloon_cpu_notifier);
+               put_online_cpus();
        }
 
        pr_info("Initialising balloon driver\n");