percpu: use group information to allocate vmap areas sparsely

ai->groups[] contains which units need to be put consecutively and at
what offset from the chunk base address.  Compile this information
into pcpu_group_offsets[] and pcpu_group_sizes[] in
pcpu_setup_first_chunk() and use them to allocate sparse vm areas
using pcpu_get_vm_areas().

This will be used to allow directly using sparse NUMA memories as
percpu areas.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Nick Piggin <npiggin@suse.de>

1 files changed, 26 insertions, 9 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index 548624309f83..cc9c4c64606d 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -98,7 +98,7 @@ struct pcpu_chunk {
         int                     map_used;       /* # of map entries used */
         int                     map_alloc;      /* # of map entries allocated */
         int                     *map;           /* allocation map */
-        struct vm_struct        *vm;            /* mapped vmalloc region */
+        struct vm_struct        **vms;          /* mapped vmalloc regions */
         bool                    immutable;      /* no [de]population allowed */
         unsigned long           populated[];    /* populated bitmap */
 };
@@ -106,7 +106,7 @@ struct pcpu_chunk {
 static int pcpu_unit_pages __read_mostly;
 static int pcpu_unit_size __read_mostly;
 static int pcpu_nr_units __read_mostly;
-static int pcpu_chunk_size __read_mostly;
+static int pcpu_atom_size __read_mostly;
 static int pcpu_nr_slots __read_mostly;
 static size_t pcpu_chunk_struct_size __read_mostly;
 
@@ -121,6 +121,11 @@ EXPORT_SYMBOL_GPL(pcpu_base_addr);
 static const int *pcpu_unit_map __read_mostly;          /* cpu -> unit */
 const unsigned long *pcpu_unit_offsets __read_mostly;   /* cpu -> unit offset */
 
+/* group information, used for vm allocation */
+static int pcpu_nr_groups __read_mostly;
+static const unsigned long *pcpu_group_offsets __read_mostly;
+static const size_t *pcpu_group_sizes __read_mostly;
+
 /*
  * The first chunk which always exists.  Note that unlike other
  * chunks, this one can be allocated and mapped in several different
@@ -988,8 +993,8 @@ static void free_pcpu_chunk(struct pcpu_chunk *chunk)
 {
         if (!chunk)
                 return;
-        if (chunk->vm)
-                free_vm_area(chunk->vm);
+        if (chunk->vms)
+                pcpu_free_vm_areas(chunk->vms, pcpu_nr_groups);
         pcpu_mem_free(chunk->map, chunk->map_alloc * sizeof(chunk->map[0]));
         kfree(chunk);
 }
@@ -1006,8 +1011,10 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
         chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
         chunk->map[chunk->map_used++] = pcpu_unit_size;
 
-        chunk->vm = get_vm_area(pcpu_chunk_size, VM_ALLOC);
-        if (!chunk->vm) {
+        chunk->vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
+                                       pcpu_nr_groups, pcpu_atom_size,
+                                       GFP_KERNEL);
+        if (!chunk->vms) {
                 free_pcpu_chunk(chunk);
                 return NULL;
         }
@@ -1015,7 +1022,7 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
         INIT_LIST_HEAD(&chunk->list);
         chunk->free_size = pcpu_unit_size;
         chunk->contig_hint = pcpu_unit_size;
-        chunk->base_addr = chunk->vm->addr;
+        chunk->base_addr = chunk->vms[0]->addr - pcpu_group_offsets[0];
 
         return chunk;
 }
@@ -1571,6 +1578,8 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         size_t dyn_size = ai->dyn_size;
         size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
         struct pcpu_chunk *schunk, *dchunk = NULL;
+        unsigned long *group_offsets;
+        size_t *group_sizes;
         unsigned long *unit_off;
         unsigned int cpu;
         int *unit_map;
@@ -1588,7 +1597,9 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
 
         pcpu_dump_alloc_info(KERN_DEBUG, ai);
 
-        /* determine number of units and initialize unit_map and base */
+        /* process group information and build config tables accordingly */
+        group_offsets = alloc_bootmem(ai->nr_groups * sizeof(group_offsets[0]));
+        group_sizes = alloc_bootmem(ai->nr_groups * sizeof(group_sizes[0]));
         unit_map = alloc_bootmem(nr_cpu_ids * sizeof(unit_map[0]));
         unit_off = alloc_bootmem(nr_cpu_ids * sizeof(unit_off[0]));
 
@@ -1599,6 +1610,9 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
                 const struct pcpu_group_info *gi = &ai->groups[group];
 
+                group_offsets[group] = gi->base_offset;
+                group_sizes[group] = gi->nr_units * ai->unit_size;
+
                 for (i = 0; i < gi->nr_units; i++) {
                         cpu = gi->cpu_map[i];
                         if (cpu == NR_CPUS)
@@ -1620,13 +1634,16 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         for_each_possible_cpu(cpu)
                 BUG_ON(unit_map[cpu] == NR_CPUS);
 
+        pcpu_nr_groups = ai->nr_groups;
+        pcpu_group_offsets = group_offsets;
+        pcpu_group_sizes = group_sizes;
         pcpu_unit_map = unit_map;
         pcpu_unit_offsets = unit_off;
 
         /* determine basic parameters */
         pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
         pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
-        pcpu_chunk_size = pcpu_nr_units * pcpu_unit_size;
+        pcpu_atom_size = ai->atom_size;
         pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
                 BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);