percpu: make allocation failures more verbose

[linux-block.git] / mm / percpu.c

diff --git a/mm/percpu.c b/mm/percpu.c
index 83617ca3ba527190c17d23b846245ad79c78ccb7..4a048abad0436d2bd883fd25395b1e44c0b6b99f 100644 (file)
--- 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;
 }