xen/balloon: don't alloc page while non-preemptible

[~andy/linux] / drivers / xen / balloon.c

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 3101cf6daf5662440682ee5746a5b15d2da04d6c..b232908a61925724bb61bc0f8a09ecbca6b753e6 100644 (file)
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -349,8 +349,6 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
                BUG_ON(page == NULL);
 
                pfn = page_to_pfn(page);
-               BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
-                      phys_to_machine_mapping_valid(pfn));
 
                set_phys_to_machine(pfn, frame_list[i]);
 
@@ -380,6 +378,7 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
        enum bp_state state = BP_DONE;
        unsigned long  pfn, i;
        struct page   *page;
+       struct page   *scratch_page;
        int ret;
        struct xen_memory_reservation reservation = {
                .address_bits = 0,
@@ -412,34 +411,35 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
 
                scrub_page(page);
 
+               /*
+                * Ballooned out frames are effectively replaced with
+                * a scratch frame.  Ensure direct mappings and the
+                * p2m are consistent.
+                */
+               scratch_page = get_balloon_scratch_page();
 #ifdef CONFIG_XEN_HAVE_PVMMU
                if (xen_pv_domain() && !PageHighMem(page)) {
                        ret = HYPERVISOR_update_va_mapping(
                                (unsigned long)__va(pfn << PAGE_SHIFT),
-                               pfn_pte(page_to_pfn(__get_cpu_var(balloon_scratch_page)),
+                               pfn_pte(page_to_pfn(scratch_page),
                                        PAGE_KERNEL_RO), 0);
                        BUG_ON(ret);
                }
 #endif
-       }
-
-       /* Ensure that ballooned highmem pages don't have kmaps. */
-       kmap_flush_unused();
-       flush_tlb_all();
-
-       /* No more mappings: invalidate P2M and add to balloon. */
-       for (i = 0; i < nr_pages; i++) {
-               pfn = mfn_to_pfn(frame_list[i]);
                if (!xen_feature(XENFEAT_auto_translated_physmap)) {
                        unsigned long p;
-                       struct page *pg;
-                       pg = __get_cpu_var(balloon_scratch_page);
-                       p = page_to_pfn(pg);
+                       p = page_to_pfn(scratch_page);
                        __set_phys_to_machine(pfn, pfn_to_mfn(p));
                }
+               put_balloon_scratch_page();
+
                balloon_append(pfn_to_page(pfn));
        }
 
+       /* Ensure that ballooned highmem pages don't have kmaps. */
+       kmap_flush_unused();
+       flush_tlb_all();
+
        set_xen_guest_handle(reservation.extent_start, frame_list);
        reservation.nr_extents   = nr_pages;
        ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);