1 files changed, 33 insertions, 17 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index b70f2acd8853..3311c8919f37 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -8,12 +8,12 @@
  *
  * This is percpu allocator which can handle both static and dynamic
  * areas.  Percpu areas are allocated in chunks in vmalloc area.  Each
- * chunk is consisted of num_possible_cpus() units and the first chunk
- * is used for static percpu variables in the kernel image (special
- * boot time alloc/init handling necessary as these areas need to be
- * brought up before allocation services are running).  Unit grows as
- * necessary and all units grow or shrink in unison.  When a chunk is
- * filled up, another chunk is allocated.  ie. in vmalloc area
+ * chunk is consisted of nr_cpu_ids units and the first chunk is used
+ * for static percpu variables in the kernel image (special boot time
+ * alloc/init handling necessary as these areas need to be brought up
+ * before allocation services are running).  Unit grows as necessary
+ * and all units grow or shrink in unison.  When a chunk is filled up,
+ * another chunk is allocated.  ie. in vmalloc area
  *
  *  c0                           c1                         c2
  *  -------------------          -------------------        ------------
@@ -197,7 +197,12 @@ static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
 static bool pcpu_chunk_page_occupied(struct pcpu_chunk *chunk,
                                      int page_idx)
 {
-        return *pcpu_chunk_pagep(chunk, 0, page_idx) != NULL;
+        /*
+         * Any possible cpu id can be used here, so there's no need to
+         * worry about preemption or cpu hotplug.
+         */
+        return *pcpu_chunk_pagep(chunk, raw_smp_processor_id(),
+                                 page_idx) != NULL;
 }
 
 /* set the pointer to a chunk in a page struct */
@@ -297,6 +302,14 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
                 return pcpu_first_chunk;
         }
 
+        /*
+         * The address is relative to unit0 which might be unused and
+         * thus unmapped.  Offset the address to the unit space of the
+         * current processor before looking it up in the vmalloc
+         * space.  Note that any possible cpu id can be used here, so
+         * there's no need to worry about preemption or cpu hotplug.
+         */
+        addr += raw_smp_processor_id() * pcpu_unit_size;
         return pcpu_get_page_chunk(vmalloc_to_page(addr));
 }
 
@@ -558,7 +571,7 @@ static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme)
 static void pcpu_unmap(struct pcpu_chunk *chunk, int page_start, int page_end,
                        bool flush_tlb)
 {
-        unsigned int last = num_possible_cpus() - 1;
+        unsigned int last = nr_cpu_ids - 1;
         unsigned int cpu;
 
         /* unmap must not be done on immutable chunk */
@@ -643,7 +656,7 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size,
  */
 static int pcpu_map(struct pcpu_chunk *chunk, int page_start, int page_end)
 {
-        unsigned int last = num_possible_cpus() - 1;
+        unsigned int last = nr_cpu_ids - 1;
         unsigned int cpu;
         int err;
 
@@ -749,7 +762,7 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
         chunk->map[chunk->map_used++] = pcpu_unit_size;
         chunk->page = chunk->page_ar;
 
-        chunk->vm = get_vm_area(pcpu_chunk_size, GFP_KERNEL);
+        chunk->vm = get_vm_area(pcpu_chunk_size, VM_ALLOC);
         if (!chunk->vm) {
                 free_pcpu_chunk(chunk);
                 return NULL;
@@ -1067,9 +1080,9 @@ size_t __init pcpu_setup_first_chunk(pcpu_get_page_fn_t get_page_fn,
                                         PFN_UP(size_sum));
 
         pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
-        pcpu_chunk_size = num_possible_cpus() * pcpu_unit_size;
+        pcpu_chunk_size = nr_cpu_ids * pcpu_unit_size;
         pcpu_chunk_struct_size = sizeof(struct pcpu_chunk)
-                + num_possible_cpus() * pcpu_unit_pages * sizeof(struct page *);
+                + nr_cpu_ids * pcpu_unit_pages * sizeof(struct page *);
 
         if (dyn_size < 0)
                 dyn_size = pcpu_unit_size - static_size - reserved_size;
@@ -1248,7 +1261,7 @@ ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
         } else
                 pcpue_unit_size = max_t(size_t, pcpue_size, PCPU_MIN_UNIT_SIZE);
 
-        chunk_size = pcpue_unit_size * num_possible_cpus();
+        chunk_size = pcpue_unit_size * nr_cpu_ids;
 
         pcpue_ptr = __alloc_bootmem_nopanic(chunk_size, PAGE_SIZE,
                                             __pa(MAX_DMA_ADDRESS));
@@ -1259,12 +1272,15 @@ ssize_t __init pcpu_embed_first_chunk(size_t static_size, size_t reserved_size,
         }
 
         /* return the leftover and copy */
-        for_each_possible_cpu(cpu) {
+        for (cpu = 0; cpu < nr_cpu_ids; 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);
+                if (cpu_possible(cpu)) {
+                        free_bootmem(__pa(ptr + pcpue_size),
+                                     pcpue_unit_size - pcpue_size);
+                        memcpy(ptr, __per_cpu_load, static_size);
+                } else
+                        free_bootmem(__pa(ptr), pcpue_unit_size);
         }
 
         /* we're ready, commit */