1 files changed, 157 insertions, 60 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index 43d8cacfdaa5..5adfc268b408 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -153,7 +153,10 @@ static int pcpu_reserved_chunk_limit;
  *
  * During allocation, pcpu_alloc_mutex is kept locked all the time and
  * pcpu_lock is grabbed and released as necessary.  All actual memory
- * allocations are done using GFP_KERNEL with pcpu_lock released.
+ * allocations are done using GFP_KERNEL with pcpu_lock released.  In
+ * general, percpu memory can't be allocated with irq off but
+ * irqsave/restore are still used in alloc path so that it can be used
+ * from early init path - sched_init() specifically.
  *
  * Free path accesses and alters only the index data structures, so it
  * can be safely called from atomic context.  When memory needs to be
@@ -352,62 +355,86 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
 }
 
 /**
- * pcpu_extend_area_map - extend area map for allocation
- * @chunk: target chunk
+ * pcpu_need_to_extend - determine whether chunk area map needs to be extended
+ * @chunk: chunk of interest
  *
- * Extend area map of @chunk so that it can accomodate an allocation.
- * A single allocation can split an area into three areas, so this
- * function makes sure that @chunk->map has at least two extra slots.
+ * Determine whether area map of @chunk needs to be extended to
+ * accomodate a new allocation.
  *
  * CONTEXT:
- * pcpu_alloc_mutex, pcpu_lock.  pcpu_lock is released and reacquired
- * if area map is extended.
+ * pcpu_lock.
  *
  * RETURNS:
- * 0 if noop, 1 if successfully extended, -errno on failure.
+ * New target map allocation length if extension is necessary, 0
+ * otherwise.
  */
-static int pcpu_extend_area_map(struct pcpu_chunk *chunk)
+static int pcpu_need_to_extend(struct pcpu_chunk *chunk)
 {
         int new_alloc;
-        int *new;
-        size_t size;
 
-        /* has enough? */
         if (chunk->map_alloc >= chunk->map_used + 2)
                 return 0;
 
-        spin_unlock_irq(&pcpu_lock);
-
         new_alloc = PCPU_DFL_MAP_ALLOC;
         while (new_alloc < chunk->map_used + 2)
                 new_alloc *= 2;
 
-        new = pcpu_mem_alloc(new_alloc * sizeof(new[0]));
-        if (!new) {
-                spin_lock_irq(&pcpu_lock);
+        return new_alloc;
+}
+
+/**
+ * pcpu_extend_area_map - extend area map of a chunk
+ * @chunk: chunk of interest
+ * @new_alloc: new target allocation length of the area map
+ *
+ * Extend area map of @chunk to have @new_alloc entries.
+ *
+ * CONTEXT:
+ * Does GFP_KERNEL allocation.  Grabs and releases pcpu_lock.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+static int pcpu_extend_area_map(struct pcpu_chunk *chunk, int new_alloc)
+{
+        int *old = NULL, *new = NULL;
+        size_t old_size = 0, new_size = new_alloc * sizeof(new[0]);
+        unsigned long flags;
+
+        new = pcpu_mem_alloc(new_size);
+        if (!new)
                 return -ENOMEM;
-        }
 
-        /*
-         * Acquire pcpu_lock and switch to new area map.  Only free
-         * could have happened inbetween, so map_used couldn't have
-         * grown.
-         */
-        spin_lock_irq(&pcpu_lock);
-        BUG_ON(new_alloc < chunk->map_used + 2);
+        /* acquire pcpu_lock and switch to new area map */
+        spin_lock_irqsave(&pcpu_lock, flags);
+
+        if (new_alloc <= chunk->map_alloc)
+                goto out_unlock;
 
-        size = chunk->map_alloc * sizeof(chunk->map[0]);
-        memcpy(new, chunk->map, size);
+        old_size = chunk->map_alloc * sizeof(chunk->map[0]);
+        memcpy(new, chunk->map, old_size);
 
         /*
          * map_alloc < PCPU_DFL_MAP_ALLOC indicates that the chunk is
          * one of the first chunks and still using static map.
          */
         if (chunk->map_alloc >= PCPU_DFL_MAP_ALLOC)
-                pcpu_mem_free(chunk->map, size);
+                old = chunk->map;
 
         chunk->map_alloc = new_alloc;
         chunk->map = new;
+        new = NULL;
+
+out_unlock:
+        spin_unlock_irqrestore(&pcpu_lock, flags);
+
+        /*
+         * pcpu_mem_free() might end up calling vfree() which uses
+         * IRQ-unsafe lock and thus can't be called under pcpu_lock.
+         */
+        pcpu_mem_free(old, old_size);
+        pcpu_mem_free(new, new_size);
+
         return 0;
 }
 
@@ -1043,8 +1070,11 @@ 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;
-        int slot, off;
+        const char *err;
+        int slot, off, new_alloc;
+        unsigned long flags;
 
         if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
                 WARN(true, "illegal size (%zu) or align (%zu) for "
@@ -1053,17 +1083,31 @@ static void *pcpu_alloc(size_t size, size_t align, bool reserved)
         }
 
         mutex_lock(&pcpu_alloc_mutex);
-        spin_lock_irq(&pcpu_lock);
+        spin_lock_irqsave(&pcpu_lock, flags);
 
         /* serve reserved allocations from the reserved chunk if available */
         if (reserved && pcpu_reserved_chunk) {
                 chunk = pcpu_reserved_chunk;
-                if (size > chunk->contig_hint ||
-                    pcpu_extend_area_map(chunk) < 0)
+
+                if (size > chunk->contig_hint) {
+                        err = "alloc from reserved chunk failed";
                         goto fail_unlock;
+                }
+
+                while ((new_alloc = pcpu_need_to_extend(chunk))) {
+                        spin_unlock_irqrestore(&pcpu_lock, flags);
+                        if (pcpu_extend_area_map(chunk, new_alloc) < 0) {
+                                err = "failed to extend area map of reserved chunk";
+                                goto fail_unlock_mutex;
+                        }
+                        spin_lock_irqsave(&pcpu_lock, flags);
+                }
+
                 off = pcpu_alloc_area(chunk, size, align);
                 if (off >= 0)
                         goto area_found;
+
+                err = "alloc from reserved chunk failed";
                 goto fail_unlock;
         }
 
@@ -1074,13 +1118,20 @@ restart:
                         if (size > chunk->contig_hint)
                                 continue;
 
-                        switch (pcpu_extend_area_map(chunk)) {
-                        case 0:
-                                break;
-                        case 1:
-                                goto restart;   /* pcpu_lock dropped, restart */
-                        default:
-                                goto fail_unlock;
+                        new_alloc = pcpu_need_to_extend(chunk);
+                        if (new_alloc) {
+                                spin_unlock_irqrestore(&pcpu_lock, flags);
+                                if (pcpu_extend_area_map(chunk,
+                                                         new_alloc) < 0) {
+                                        err = "failed to extend area map";
+                                        goto fail_unlock_mutex;
+                                }
+                                spin_lock_irqsave(&pcpu_lock, flags);
+                                /*
+                                 * pcpu_lock has been dropped, need to
+                                 * restart cpu_slot list walking.
+                                 */
+                                goto restart;
                         }
 
                         off = pcpu_alloc_area(chunk, size, align);
@@ -1090,23 +1141,26 @@ restart:
         }
 
         /* hmmm... no space left, create a new chunk */
-        spin_unlock_irq(&pcpu_lock);
+        spin_unlock_irqrestore(&pcpu_lock, flags);
 
         chunk = alloc_pcpu_chunk();
-        if (!chunk)
+        if (!chunk) {
+                err = "failed to allocate new chunk";
                 goto fail_unlock_mutex;
+        }
 
-        spin_lock_irq(&pcpu_lock);
+        spin_lock_irqsave(&pcpu_lock, flags);
         pcpu_chunk_relocate(chunk, -1);
         goto restart;
 
 area_found:
-        spin_unlock_irq(&pcpu_lock);
+        spin_unlock_irqrestore(&pcpu_lock, flags);
 
         /* populate, map and clear the area */
         if (pcpu_populate_chunk(chunk, off, size)) {
-                spin_lock_irq(&pcpu_lock);
+                spin_lock_irqsave(&pcpu_lock, flags);
                 pcpu_free_area(chunk, off);
+                err = "failed to populate";
                 goto fail_unlock;
         }
 
@@ -1116,9 +1170,16 @@ area_found:
         return __addr_to_pcpu_ptr(chunk->base_addr + off);
 
 fail_unlock:
-        spin_unlock_irq(&pcpu_lock);
+        spin_unlock_irqrestore(&pcpu_lock, flags);
 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 +1408,10 @@ 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 +1639,7 @@ 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 +1651,26 @@ 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 +1679,7 @@ 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 +1693,9 @@ 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 +1708,11 @@ 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 +1862,7 @@ 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 +1912,25 @@ 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_t(size_t, 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%zx 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,