1 files changed, 282 insertions, 76 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index 2196fae24f00..b3d0bcff8c7c 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -59,6 +59,7 @@
 #include <linux/bitmap.h>
 #include <linux/bootmem.h>
 #include <linux/list.h>
+#include <linux/log2.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -1594,75 +1595,259 @@ out_free_ar:
  * Large page remapping first chunk setup helper
  */
 #ifdef CONFIG_NEED_MULTIPLE_NODES
+
+/**
+ * pcpu_lpage_build_unit_map - build unit_map for large page remapping
+ * @static_size: the size of static percpu area in bytes
+ * @reserved_size: the size of reserved percpu area in bytes
+ * @dyn_sizep: in/out parameter for dynamic size, -1 for auto
+ * @unit_sizep: out parameter for unit size
+ * @unit_map: unit_map to be filled
+ * @cpu_distance_fn: callback to determine distance between cpus
+ *
+ * This function builds cpu -> unit map and determine other parameters
+ * considering needed percpu size, large page size and distances
+ * between CPUs in NUMA.
+ *
+ * CPUs which are of LOCAL_DISTANCE both ways are grouped together and
+ * may share units in the same large page.  The returned configuration
+ * is guaranteed to have CPUs on different nodes on different large
+ * pages and >=75% usage of allocated virtual address space.
+ *
+ * RETURNS:
+ * On success, fills in @unit_map, sets *@dyn_sizep, *@unit_sizep and
+ * returns the number of units to be allocated.  -errno on failure.
+ */
+int __init pcpu_lpage_build_unit_map(size_t static_size, size_t reserved_size,
+                                     ssize_t *dyn_sizep, size_t *unit_sizep,
+                                     size_t lpage_size, int *unit_map,
+                                     pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
+{
+        static int group_map[NR_CPUS] __initdata;
+        static int group_cnt[NR_CPUS] __initdata;
+        int group_cnt_max = 0;
+        size_t size_sum, min_unit_size, alloc_size;
+        int upa, max_upa, uninitialized_var(best_upa);  /* units_per_alloc */
+        int last_allocs;
+        unsigned int cpu, tcpu;
+        int group, unit;
+
+        /*
+         * Determine min_unit_size, alloc_size and max_upa such that
+         * alloc_size is multiple of lpage_size and is the smallest
+         * which can accomodate 4k aligned segments which are equal to
+         * or larger than min_unit_size.
+         */
+        size_sum = pcpu_calc_fc_sizes(static_size, reserved_size, dyn_sizep);
+        min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
+
+        alloc_size = roundup(min_unit_size, lpage_size);
+        upa = alloc_size / min_unit_size;
+        while (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
+                upa--;
+        max_upa = upa;
+
+        /* group cpus according to their proximity */
+        for_each_possible_cpu(cpu) {
+                group = 0;
+        next_group:
+                for_each_possible_cpu(tcpu) {
+                        if (cpu == tcpu)
+                                break;
+                        if (group_map[tcpu] == group &&
+                            (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
+                             cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
+                                group++;
+                                goto next_group;
+                        }
+                }
+                group_map[cpu] = group;
+                group_cnt[group]++;
+                group_cnt_max = max(group_cnt_max, group_cnt[group]);
+        }
+
+        /*
+         * Expand unit size until address space usage goes over 75%
+         * and then as much as possible without using more address
+         * space.
+         */
+        last_allocs = INT_MAX;
+        for (upa = max_upa; upa; upa--) {
+                int allocs = 0, wasted = 0;
+
+                if (alloc_size % upa || ((alloc_size / upa) & ~PAGE_MASK))
+                        continue;
+
+                for (group = 0; group_cnt[group]; group++) {
+                        int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
+                        allocs += this_allocs;
+                        wasted += this_allocs * upa - group_cnt[group];
+                }
+
+                /*
+                 * Don't accept if wastage is over 25%.  The
+                 * greater-than comparison ensures upa==1 always
+                 * passes the following check.
+                 */
+                if (wasted > num_possible_cpus() / 3)
+                        continue;
+
+                /* and then don't consume more memory */
+                if (allocs > last_allocs)
+                        break;
+                last_allocs = allocs;
+                best_upa = upa;
+        }
+        *unit_sizep = alloc_size / best_upa;
+
+        /* assign units to cpus accordingly */
+        unit = 0;
+        for (group = 0; group_cnt[group]; group++) {
+                for_each_possible_cpu(cpu)
+                        if (group_map[cpu] == group)
+                                unit_map[cpu] = unit++;
+                unit = roundup(unit, best_upa);
+        }
+
+        return unit;    /* unit contains aligned number of units */
+}
+
 struct pcpul_ent {
-        unsigned int    cpu;
         void            *ptr;
+        void            *map_addr;
 };
 
 static size_t pcpul_size;
-static size_t pcpul_unit_size;
+static size_t pcpul_lpage_size;
+static int pcpul_nr_lpages;
 static struct pcpul_ent *pcpul_map;
-static struct vm_struct pcpul_vm;
+
+static bool __init pcpul_unit_to_cpu(int unit, const int *unit_map,
+                                     unsigned int *cpup)
+{
+        unsigned int cpu;
+
+        for_each_possible_cpu(cpu)
+                if (unit_map[cpu] == unit) {
+                        if (cpup)
+                                *cpup = cpu;
+                        return true;
+                }
+
+        return false;
+}
+
+static void __init pcpul_lpage_dump_cfg(const char *lvl, size_t static_size,
+                                        size_t reserved_size, size_t dyn_size,
+                                        size_t unit_size, size_t lpage_size,
+                                        const int *unit_map, int nr_units)
+{
+        int width = 1, v = nr_units;
+        char empty_str[] = "--------";
+        int upl, lpl;   /* units per lpage, lpage per line */
+        unsigned int cpu;
+        int lpage, unit;
+
+        while (v /= 10)
+                width++;
+        empty_str[min_t(int, width, sizeof(empty_str) - 1)] = '\0';
+
+        upl = max_t(int, lpage_size / unit_size, 1);
+        lpl = rounddown_pow_of_two(max_t(int, 60 / (upl * (width + 1) + 2), 1));
+
+        printk("%spcpu-lpage: sta/res/dyn=%zu/%zu/%zu unit=%zu lpage=%zu", lvl,
+               static_size, reserved_size, dyn_size, unit_size, lpage_size);
+
+        for (lpage = 0, unit = 0; unit < nr_units; unit++) {
+                if (!(unit % upl)) {
+                        if (!(lpage++ % lpl)) {
+                                printk("\n");
+                                printk("%spcpu-lpage: ", lvl);
+                        } else
+                                printk("| ");
+                }
+                if (pcpul_unit_to_cpu(unit, unit_map, &cpu))
+                        printk("%0*d ", width, cpu);
+                else
+                        printk("%s ", empty_str);
+        }
+        printk("\n");
+}
 
 /**
  * pcpu_lpage_first_chunk - remap the first percpu chunk using large page
  * @static_size: the size of static percpu area in bytes
  * @reserved_size: the size of reserved percpu area in bytes
- * @dyn_size: free size for dynamic allocation in bytes, -1 for auto
+ * @dyn_size: free size for dynamic allocation in bytes
+ * @unit_size: unit size in bytes
  * @lpage_size: the size of a large page
+ * @unit_map: cpu -> unit mapping
+ * @nr_units: the number of units
  * @alloc_fn: function to allocate percpu lpage, always called with lpage_size
  * @free_fn: function to free percpu memory, @size <= lpage_size
  * @map_fn: function to map percpu lpage, always called with lpage_size
  *
- * This allocator uses large page as unit.  A large page is allocated
- * for each cpu and each is remapped into vmalloc area using large
- * page mapping.  As large page can be quite large, only part of it is
- * used for the first chunk.  Unused part is returned to the bootmem
- * allocator.
- *
- * So, the large pages are mapped twice - once to the physical mapping
- * and to the vmalloc area for the first percpu chunk.  The double
- * mapping does add one more large TLB entry pressure but still is
- * much better than only using 4k mappings while still being NUMA
- * friendly.
+ * This allocator uses large page to build and map the first chunk.
+ * Unlike other helpers, the caller should always specify @dyn_size
+ * and @unit_size.  These parameters along with @unit_map and
+ * @nr_units can be determined using pcpu_lpage_build_unit_map().
+ * This two stage initialization is to allow arch code to evaluate the
+ * parameters before committing to it.
+ *
+ * Large pages are allocated as directed by @unit_map and other
+ * parameters and mapped to vmalloc space.  Unused holes are returned
+ * to the page allocator.  Note that these holes end up being actively
+ * mapped twice - once to the physical mapping and to the vmalloc area
+ * for the first percpu chunk.  Depending on architecture, this might
+ * cause problem when changing page attributes of the returned area.
+ * These double mapped areas can be detected using
+ * pcpu_lpage_remapped().
  *
  * RETURNS:
  * The determined pcpu_unit_size which can be used to initialize
  * percpu access on success, -errno on failure.
  */
 ssize_t __init pcpu_lpage_first_chunk(size_t static_size, size_t reserved_size,
-                                      ssize_t dyn_size, size_t lpage_size,
+                                      size_t dyn_size, size_t unit_size,
+                                      size_t lpage_size, const int *unit_map,
+                                      int nr_units,
                                       pcpu_fc_alloc_fn_t alloc_fn,
                                       pcpu_fc_free_fn_t free_fn,
                                       pcpu_fc_map_fn_t map_fn)
 {
-        size_t size_sum;
+        static struct vm_struct vm;
+        size_t chunk_size = unit_size * nr_units;
         size_t map_size;
         unsigned int cpu;
-        int i, j;
         ssize_t ret;
+        int i, j, unit;
 
-        /*
-         * Currently supports only single page.  Supporting multiple
-         * pages won't be too difficult if it ever becomes necessary.
-         */
-        size_sum = pcpu_calc_fc_sizes(static_size, reserved_size, &dyn_size);
+        pcpul_lpage_dump_cfg(KERN_DEBUG, static_size, reserved_size, dyn_size,
+                             unit_size, lpage_size, unit_map, nr_units);
 
-        pcpul_unit_size = lpage_size;
-        pcpul_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
-        if (pcpul_size > pcpul_unit_size) {
-                pr_warning("PERCPU: static data is larger than large page, "
-                           "can't use large page\n");
-                return -EINVAL;
-        }
+        BUG_ON(chunk_size % lpage_size);
+
+        pcpul_size = static_size + reserved_size + dyn_size;
+        pcpul_lpage_size = lpage_size;
+        pcpul_nr_lpages = chunk_size / lpage_size;
 
         /* allocate pointer array and alloc large pages */
-        map_size = PFN_ALIGN(num_possible_cpus() * sizeof(pcpul_map[0]));
+        map_size = pcpul_nr_lpages * sizeof(pcpul_map[0]);
         pcpul_map = alloc_bootmem(map_size);
 
-        for_each_possible_cpu(cpu) {
+        /* allocate all pages */
+        for (i = 0; i < pcpul_nr_lpages; i++) {
+                size_t offset = i * lpage_size;
+                int first_unit = offset / unit_size;
+                int last_unit = (offset + lpage_size - 1) / unit_size;
                 void *ptr;
 
+                /* find out which cpu is mapped to this unit */
+                for (unit = first_unit; unit <= last_unit; unit++)
+                        if (pcpul_unit_to_cpu(unit, unit_map, &cpu))
+                                goto found;
+                continue;
+        found:
                 ptr = alloc_fn(cpu, lpage_size);
                 if (!ptr) {
                         pr_warning("PERCPU: failed to allocate large page "
@@ -1670,53 +1855,79 @@ ssize_t __init pcpu_lpage_first_chunk(size_t static_size, size_t reserved_size,
                         goto enomem;
                 }
 
-                /*
-                 * Only use pcpul_size bytes and give back the rest.
-                 *
-                 * Ingo: The lpage_size up-rounding bootmem is needed
-                 * to make sure the partial lpage is still fully RAM -
-                 * it's not well-specified to have a incompatible area
-                 * (unmapped RAM, device memory, etc.) in that hole.
-                 */
-                free_fn(ptr + pcpul_size, lpage_size - pcpul_size);
-
-                pcpul_map[cpu].cpu = cpu;
-                pcpul_map[cpu].ptr = ptr;
+                pcpul_map[i].ptr = ptr;
+        }
 
-                memcpy(ptr, __per_cpu_load, static_size);
+        /* return unused holes */
+        for (unit = 0; unit < nr_units; unit++) {
+                size_t start = unit * unit_size;
+                size_t end = start + unit_size;
+                size_t off, next;
+
+                /* don't free used part of occupied unit */
+                if (pcpul_unit_to_cpu(unit, unit_map, NULL))
+                        start += pcpul_size;
+
+                /* unit can span more than one page, punch the holes */
+                for (off = start; off < end; off = next) {
+                        void *ptr = pcpul_map[off / lpage_size].ptr;
+                        next = min(roundup(off + 1, lpage_size), end);
+                        if (ptr)
+                                free_fn(ptr + off % lpage_size, next - off);
+                }
         }
 
-        /* allocate address and map */
-        pcpul_vm.flags = VM_ALLOC;
-        pcpul_vm.size = num_possible_cpus() * pcpul_unit_size;
-        vm_area_register_early(&pcpul_vm, pcpul_unit_size);
+        /* allocate address, map and copy */
+        vm.flags = VM_ALLOC;
+        vm.size = chunk_size;
+        vm_area_register_early(&vm, unit_size);
+
+        for (i = 0; i < pcpul_nr_lpages; i++) {
+                if (!pcpul_map[i].ptr)
+                        continue;
+                pcpul_map[i].map_addr = vm.addr + i * lpage_size;
+                map_fn(pcpul_map[i].ptr, lpage_size, pcpul_map[i].map_addr);
+        }
 
         for_each_possible_cpu(cpu)
-                map_fn(pcpul_map[cpu].ptr, pcpul_unit_size,
-                       pcpul_vm.addr + cpu * pcpul_unit_size);
+                memcpy(vm.addr + unit_map[cpu] * unit_size, __per_cpu_load,
+                       static_size);
 
         /* we're ready, commit */
         pr_info("PERCPU: Remapped at %p with large pages, static data "
-                "%zu bytes\n", pcpul_vm.addr, static_size);
+                "%zu bytes\n", vm.addr, static_size);
 
         ret = pcpu_setup_first_chunk(static_size, reserved_size, dyn_size,
-                                     pcpul_unit_size, pcpul_vm.addr, NULL);
-
-        /* sort pcpul_map array for pcpu_lpage_remapped() */
-        for (i = 0; i < num_possible_cpus() - 1; i++)
-                for (j = i + 1; j < num_possible_cpus(); j++)
-                        if (pcpul_map[i].ptr > pcpul_map[j].ptr) {
-                                struct pcpul_ent tmp = pcpul_map[i];
-                                pcpul_map[i] = pcpul_map[j];
-                                pcpul_map[j] = tmp;
-                        }
+                                     unit_size, vm.addr, unit_map);
+
+        /*
+         * Sort pcpul_map array for pcpu_lpage_remapped().  Unmapped
+         * lpages are pushed to the end and trimmed.
+         */
+        for (i = 0; i < pcpul_nr_lpages - 1; i++)
+                for (j = i + 1; j < pcpul_nr_lpages; j++) {
+                        struct pcpul_ent tmp;
+
+                        if (!pcpul_map[j].ptr)
+                                continue;
+                        if (pcpul_map[i].ptr &&
+                            pcpul_map[i].ptr < pcpul_map[j].ptr)
+                                continue;
+
+                        tmp = pcpul_map[i];
+                        pcpul_map[i] = pcpul_map[j];
+                        pcpul_map[j] = tmp;
+                }
+
+        while (pcpul_nr_lpages && !pcpul_map[pcpul_nr_lpages - 1].ptr)
+                pcpul_nr_lpages--;
 
         return ret;
 
 enomem:
-        for_each_possible_cpu(cpu)
-                if (pcpul_map[cpu].ptr)
-                        free_fn(pcpul_map[cpu].ptr, pcpul_size);
+        for (i = 0; i < pcpul_nr_lpages; i++)
+                if (pcpul_map[i].ptr)
+                        free_fn(pcpul_map[i].ptr, lpage_size);
         free_bootmem(__pa(pcpul_map), map_size);
         return -ENOMEM;
 }
@@ -1739,10 +1950,10 @@ enomem:
  */
 void *pcpu_lpage_remapped(void *kaddr)
 {
-        unsigned long unit_mask = pcpul_unit_size - 1;
-        void *lpage_addr = (void *)((unsigned long)kaddr & ~unit_mask);
-        unsigned long offset = (unsigned long)kaddr & unit_mask;
-        int left = 0, right = num_possible_cpus() - 1;
+        unsigned long lpage_mask = pcpul_lpage_size - 1;
+        void *lpage_addr = (void *)((unsigned long)kaddr & ~lpage_mask);
+        unsigned long offset = (unsigned long)kaddr & lpage_mask;
+        int left = 0, right = pcpul_nr_lpages - 1;
         int pos;
 
         /* pcpul in use at all? */
@@ -1757,13 +1968,8 @@ void *pcpu_lpage_remapped(void *kaddr)
                         left = pos + 1;
                 else if (pcpul_map[pos].ptr > lpage_addr)
                         right = pos - 1;
-                else {
-                        /* it shouldn't be in the area for the first chunk */
-                        WARN_ON(offset < pcpul_size);
-
-                        return pcpul_vm.addr +
-                                pcpul_map[pos].cpu * pcpul_unit_size + offset;
-                }
+                else
+                        return pcpul_map[pos].map_addr + offset;
         }
 
         return NULL;