On Wed, 2010-09-01 at 11:42 +0300, Avi Kivity wrote: > I recently added perf_event support to kvm_stat, to display kvm > tracepoints as statistics (I'd like to fold this to tools/perf > eventually, but that's another story). However I'm seeing a resource > leak - after I quit the tool, there are quite a few references into the > kvm module: > > kvm_intel 43655 0 > kvm 272984 269 kvm_intel > > The tool is just a python script that reads > /sys/kernel/debug/tracing/events/kvm to find out which events are > available, uses perf_event_open() to create one group per cpu to which a > lot of events are attached. The only special thing I can think of is > that we use an ioctl to attach a filter to many perf_event descriptors. > > You can find the source at > http://git.kernel.org/?p=virt/kvm/qemu-kvm.git;a=blob_plain;f=kvm/kvm_stat;hb=5bd5f131b50cb373ff4e2a3632c6dad00a1f0b55. > All it needs are the kvm modules loaded; no need to actually run a > guest. Run as root. > Does something like the below cure that? I seem to remember C doesn't make any promises about the order of logic statements, hence we need to explicitly pull out that try_module_get() so that it evaluates after the rest of the conditions. --- kernel/trace/trace_event_perf.c | 10 ++++++---- 1 files changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index 000e6e8..35051f2 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -88,10 +88,11 @@ int perf_trace_init(struct perf_event *p_event) mutex_lock(&event_mutex); list_for_each_entry(tp_event, &ftrace_events, list) { if (tp_event->event.type == event_id && - tp_event->class && tp_event->class->reg && - try_module_get(tp_event->mod)) { - ret = perf_trace_event_init(tp_event, p_event); - break; + tp_event->class && tp_event->class->reg) { + if (try_module_get(tp_event->mod)) { + ret = perf_trace_event_init(tp_event, p_event); + break; + } } } mutex_unlock(&event_mutex); @@ -138,6 +139,7 @@ void perf_trace_destroy(struct perf_event *p_event) free_percpu(tp_event->perf_events); tp_event->perf_events = NULL; + module_put(tp_event->mod); if (!--total_ref_count) { for (i = 0; i < 4; i++) { -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
