1 files changed, 28 insertions, 16 deletions

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index ef3a2cd3fe64..38e2b2a470a5 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -241,24 +241,31 @@ static ssize_t __init setup_pcpu_remap(size_t static_size)
  * Embedding allocator
  *
  * The first chunk is sized to just contain the static area plus
- * PERCPU_DYNAMIC_RESERVE and allocated as a contiguous area using
- * bootmem allocator and used as-is without being mapped into vmalloc
- * area.  This enables the first chunk to piggy back on the linear
- * physical PMD mapping and doesn't add any additional pressure to
- * TLB.
+ * module and dynamic reserves, and allocated as a contiguous area
+ * using bootmem allocator and used as-is without being mapped into
+ * vmalloc area.  This enables the first chunk to piggy back on the
+ * linear physical PMD mapping and doesn't add any additional pressure
+ * to TLB.  Note that if the needed size is smaller than the minimum
+ * unit size, the leftover is returned to the bootmem allocator.
  */
 static void *pcpue_ptr __initdata;
+static size_t pcpue_size __initdata;
 static size_t pcpue_unit_size __initdata;
 
 static struct page * __init pcpue_get_page(unsigned int cpu, int pageno)
 {
-        return virt_to_page(pcpue_ptr + cpu * pcpue_unit_size
-                            + ((size_t)pageno << PAGE_SHIFT));
+        size_t off = (size_t)pageno << PAGE_SHIFT;
+
+        if (off >= pcpue_size)
+                return NULL;
+
+        return virt_to_page(pcpue_ptr + cpu * pcpue_unit_size + off);
 }
 
 static ssize_t __init setup_pcpu_embed(size_t static_size)
 {
         unsigned int cpu;
+        size_t dyn_size;
 
         /*
          * If large page isn't supported, there's no benefit in doing
@@ -269,25 +276,30 @@ static ssize_t __init setup_pcpu_embed(size_t static_size)
                 return -EINVAL;
 
         /* allocate and copy */
-        pcpue_unit_size = PFN_ALIGN(static_size + PERCPU_DYNAMIC_RESERVE);
-        pcpue_unit_size = max_t(size_t, pcpue_unit_size, PCPU_MIN_UNIT_SIZE);
+        pcpue_size = PFN_ALIGN(static_size + PERCPU_DYNAMIC_RESERVE);
+        pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
+        dyn_size = pcpue_size - static_size;
+
         pcpue_ptr = pcpu_alloc_bootmem(0, num_possible_cpus() * pcpue_unit_size,
                                        PAGE_SIZE);
         if (!pcpue_ptr)
                 return -ENOMEM;
 
-        for_each_possible_cpu(cpu)
-                memcpy(pcpue_ptr + cpu * pcpue_unit_size, __per_cpu_load,
-                       static_size);
+        for_each_possible_cpu(cpu) {
+                void *ptr = pcpue_ptr + cpu * pcpue_unit_size;
+
+                free_bootmem(__pa(ptr + pcpue_size),
+                             pcpue_unit_size - pcpue_size);
+                memcpy(ptr, __per_cpu_load, static_size);
+        }
 
         /* we're ready, commit */
         pr_info("PERCPU: Embedded %zu pages at %p, static data %zu bytes\n",
-                pcpue_unit_size >> PAGE_SHIFT, pcpue_ptr, static_size);
+                pcpue_size >> PAGE_SHIFT, pcpue_ptr, static_size);
 
         return pcpu_setup_first_chunk(pcpue_get_page, static_size,
-                                      pcpue_unit_size,
-                                      pcpue_unit_size - static_size, pcpue_ptr,
-                                      NULL);
+                                      pcpue_unit_size, dyn_size,
+                                      pcpue_ptr, NULL);
 }
 
 /*