perf_counter: Fix counter inheritance
Srivatsa Vaddagiri reported that a Java workload triggers this
warning in kernel/exit.c:
WARN_ON_ONCE(!list_empty(&tsk->perf_counter_ctx.counter_list));
Add the inherited counter propagation on self-detach, this could
cause counter leaks and incomplete stats in threaded code like
the below:
#include <pthread.h>
#include <unistd.h>
void *thread(void *arg)
{
sleep(5);
return NULL;
}
void main(void)
{
pthread_t thr;
pthread_create(&thr, NULL, thread, NULL);
}
Reported-by: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/exit.c b/kernel/exit.c
index 4741376..16d74f1 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -128,6 +128,12 @@
sig = NULL; /* Marker for below. */
}
+ /*
+ * Flush inherited counters to the parent - before the parent
+ * gets woken up by child-exit notifications.
+ */
+ perf_counter_exit_task(tsk);
+
__unhash_process(tsk);
/*