Merge branch 'work.d_name' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

[linux-2.6-microblaze.git] / lib / percpu-refcount.c

diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index e59eda0..a1071cd 100644 (file)
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -5,6 +5,7 @@
 #include <linux/sched.h>
 #include <linux/wait.h>
 #include <linux/slab.h>
+#include <linux/mm.h>
 #include <linux/percpu-refcount.h>
 
 /*
@@ -168,6 +169,7 @@ static void percpu_ref_switch_to_atomic_rcu(struct rcu_head *rcu)
                        struct percpu_ref_data, rcu);
        struct percpu_ref *ref = data->ref;
        unsigned long __percpu *percpu_count = percpu_count_ptr(ref);
+       static atomic_t underflows;
        unsigned long count = 0;
        int cpu;
 
@@ -191,9 +193,13 @@ static void percpu_ref_switch_to_atomic_rcu(struct rcu_head *rcu)
         */
        atomic_long_add((long)count - PERCPU_COUNT_BIAS, &data->count);
 
-       WARN_ONCE(atomic_long_read(&data->count) <= 0,
-                 "percpu ref (%ps) <= 0 (%ld) after switching to atomic",
-                 data->release, atomic_long_read(&data->count));
+       if (WARN_ONCE(atomic_long_read(&data->count) <= 0,
+                     "percpu ref (%ps) <= 0 (%ld) after switching to atomic",
+                     data->release, atomic_long_read(&data->count)) &&
+           atomic_inc_return(&underflows) < 4) {
+               pr_err("%s(): percpu_ref underflow", __func__);
+               mem_dump_obj(data);
+       }
 
        /* @ref is viewed as dead on all CPUs, send out switch confirmation */
        percpu_ref_call_confirm_rcu(rcu);