1 files changed, 67 insertions, 16 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index 43d8cacfdaa5..4a048abad043 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1043,7 +1043,9 @@ static struct pcpu_chunk *alloc_pcpu_chunk(void)
  */
 static void *pcpu_alloc(size_t size, size_t align, bool reserved)
 {
+        static int warn_limit = 10;
         struct pcpu_chunk *chunk;
+        const char *err;
         int slot, off;
 
         if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
@@ -1059,11 +1061,14 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved)
         if (reserved && pcpu_reserved_chunk) {
                 chunk = pcpu_reserved_chunk;
                 if (size > chunk->contig_hint ||
-                    pcpu_extend_area_map(chunk) < 0)
+                    pcpu_extend_area_map(chunk) < 0) {
+                        err = "failed to extend area map of reserved chunk";
                         goto fail_unlock;
+                }
                 off = pcpu_alloc_area(chunk, size, align);
                 if (off >= 0)
                         goto area_found;
+                err = "alloc from reserved chunk failed";
                 goto fail_unlock;
         }
 
@@ -1080,6 +1085,7 @@ restart:
                         case 1:
                                 goto restart;   /* pcpu_lock dropped, restart */
                         default:
+                                err = "failed to extend area map";
                                 goto fail_unlock;
                         }
 
@@ -1093,8 +1099,10 @@ restart:
         spin_unlock_irq(&pcpu_lock);
 
         chunk = alloc_pcpu_chunk();
-        if (!chunk)
+        if (!chunk) {
+                err = "failed to allocate new chunk";
                 goto fail_unlock_mutex;
+        }
 
         spin_lock_irq(&pcpu_lock);
         pcpu_chunk_relocate(chunk, -1);
@@ -1107,6 +1115,7 @@ area_found:
         if (pcpu_populate_chunk(chunk, off, size)) {
                 spin_lock_irq(&pcpu_lock);
                 pcpu_free_area(chunk, off);
+                err = "failed to populate";
                 goto fail_unlock;
         }
 
@@ -1119,6 +1128,13 @@ fail_unlock:
         spin_unlock_irq(&pcpu_lock);
 fail_unlock_mutex:
         mutex_unlock(&pcpu_alloc_mutex);
+        if (warn_limit) {
+                pr_warning("PERCPU: allocation failed, size=%zu align=%zu, "
+                           "%s\n", size, align, err);
+                dump_stack();
+                if (!--warn_limit)
+                        pr_info("PERCPU: limit reached, disable warning\n");
+        }
         return NULL;
 }
 
@@ -1347,6 +1363,10 @@ struct pcpu_alloc_info * __init pcpu_build_alloc_info(
         struct pcpu_alloc_info *ai;
         unsigned int *cpu_map;
 
+        /* this function may be called multiple times */
+        memset(group_map, 0, sizeof(group_map));
+        memset(group_cnt, 0, sizeof(group_map));
+
         /*
          * Determine min_unit_size, alloc_size and max_upa such that
          * alloc_size is multiple of atom_size and is the smallest
@@ -1574,6 +1594,7 @@ static void pcpu_dump_alloc_info(const char *lvl,
 int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
                                   void *base_addr)
 {
+        static char cpus_buf[4096] __initdata;
         static int smap[2], dmap[2];
         size_t dyn_size = ai->dyn_size;
         size_t size_sum = ai->static_size + ai->reserved_size + dyn_size;
@@ -1585,17 +1606,26 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         int *unit_map;
         int group, unit, i;
 
+        cpumask_scnprintf(cpus_buf, sizeof(cpus_buf), cpu_possible_mask);
+
+#define PCPU_SETUP_BUG_ON(cond) do {                                    \
+        if (unlikely(cond)) {                                           \
+                pr_emerg("PERCPU: failed to initialize, %s", #cond);    \
+                pr_emerg("PERCPU: cpu_possible_mask=%s\n", cpus_buf);   \
+                pcpu_dump_alloc_info(KERN_EMERG, ai);                   \
+                BUG();                                                  \
+        }                                                               \
+} while (0)
+
         /* sanity checks */
         BUILD_BUG_ON(ARRAY_SIZE(smap) >= PCPU_DFL_MAP_ALLOC ||
                      ARRAY_SIZE(dmap) >= PCPU_DFL_MAP_ALLOC);
-        BUG_ON(ai->nr_groups <= 0);
-        BUG_ON(!ai->static_size);
-        BUG_ON(!base_addr);
-        BUG_ON(ai->unit_size < size_sum);
-        BUG_ON(ai->unit_size & ~PAGE_MASK);
-        BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
-
-        pcpu_dump_alloc_info(KERN_DEBUG, ai);
+        PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
+        PCPU_SETUP_BUG_ON(!ai->static_size);
+        PCPU_SETUP_BUG_ON(!base_addr);
+        PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
+        PCPU_SETUP_BUG_ON(ai->unit_size & ~PAGE_MASK);
+        PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
 
         /* process group information and build config tables accordingly */
         group_offsets = alloc_bootmem(ai->nr_groups * sizeof(group_offsets[0]));
@@ -1604,7 +1634,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         unit_off = alloc_bootmem(nr_cpu_ids * sizeof(unit_off[0]));
 
         for (cpu = 0; cpu < nr_cpu_ids; cpu++)
-                unit_map[cpu] = NR_CPUS;
+                unit_map[cpu] = UINT_MAX;
         pcpu_first_unit_cpu = NR_CPUS;
 
         for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
@@ -1618,8 +1648,9 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
                         if (cpu == NR_CPUS)
                                 continue;
 
-                        BUG_ON(cpu > nr_cpu_ids || !cpu_possible(cpu));
-                        BUG_ON(unit_map[cpu] != NR_CPUS);
+                        PCPU_SETUP_BUG_ON(cpu > nr_cpu_ids);
+                        PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
+                        PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
 
                         unit_map[cpu] = unit + i;
                         unit_off[cpu] = gi->base_offset + i * ai->unit_size;
@@ -1632,7 +1663,11 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
         pcpu_nr_units = unit;
 
         for_each_possible_cpu(cpu)
-                BUG_ON(unit_map[cpu] == NR_CPUS);
+                PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
+
+        /* we're done parsing the input, undefine BUG macro and dump config */
+#undef PCPU_SETUP_BUG_ON
+        pcpu_dump_alloc_info(KERN_INFO, ai);
 
         pcpu_nr_groups = ai->nr_groups;
         pcpu_group_offsets = group_offsets;
@@ -1782,7 +1817,7 @@ int __init pcpu_embed_first_chunk(size_t reserved_size, ssize_t dyn_size,
         void *base = (void *)ULONG_MAX;
         void **areas = NULL;
         struct pcpu_alloc_info *ai;
-        size_t size_sum, areas_size;
+        size_t size_sum, areas_size, max_distance;
         int group, i, rc;
 
         ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
@@ -1832,8 +1867,24 @@ int __init pcpu_embed_first_chunk(size_t reserved_size, ssize_t dyn_size,
         }
 
         /* base address is now known, determine group base offsets */
-        for (group = 0; group < ai->nr_groups; group++)
+        max_distance = 0;
+        for (group = 0; group < ai->nr_groups; group++) {
                 ai->groups[group].base_offset = areas[group] - base;
+                max_distance = max(max_distance, ai->groups[group].base_offset);
+        }
+        max_distance += ai->unit_size;
+
+        /* warn if maximum distance is further than 75% of vmalloc space */
+        if (max_distance > (VMALLOC_END - VMALLOC_START) * 3 / 4) {
+                pr_warning("PERCPU: max_distance=0x%lx too large for vmalloc "
+                           "space 0x%lx\n",
+                           max_distance, VMALLOC_END - VMALLOC_START);
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+                /* and fail if we have fallback */
+                rc = -EINVAL;
+                goto out_free;
+#endif
+        }
 
         pr_info("PERCPU: Embedded %zu pages/cpu @%p s%zu r%zu d%zu u%zu\n",
                 PFN_DOWN(size_sum), base, ai->static_size, ai->reserved_size,