vmap: cope with vm_unmap_aliases before vmalloc_init()

Xen can end up calling vm_unmap_aliases() before vmalloc_init() has
been called.  In this case its safe to make it a simple no-op.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Linux Memory Management List <linux-mm@kvack.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 66fad3fc02b1310806ebc6302593cdad00a82c48..ba6b0f5f7fac6dcce7a9e8a7c71f00e0e691d193 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -592,6 +592,8 @@ static void free_unmap_vmap_area_addr(unsigned long addr)
 
 #define VMAP_BLOCK_SIZE                (VMAP_BBMAP_BITS * PAGE_SIZE)
 
+static bool vmap_initialized __read_mostly = false;
+
 struct vmap_block_queue {
        spinlock_t lock;
        struct list_head free;
@@ -828,6 +830,9 @@ void vm_unmap_aliases(void)
        int cpu;
        int flush = 0;
 
+       if (unlikely(!vmap_initialized))
+               return;
+
        for_each_possible_cpu(cpu) {
                struct vmap_block_queue *vbq = &per_cpu(vmap_block_queue, cpu);
                struct vmap_block *vb;
@@ -942,6 +947,8 @@ void __init vmalloc_init(void)
                INIT_LIST_HEAD(&vbq->dirty);
                vbq->nr_dirty = 0;
        }
+
+       vmap_initialized = true;
 }
 
 void unmap_kernel_range(unsigned long addr, unsigned long size)