Thanks Jiri! On Wed, Jan 16, 2019 at 1:34 PM Jiri Olsa <jo...@redhat.com> wrote: > > On Wed, Jan 16, 2019 at 10:57:49AM -0800, Song Liu wrote: > > Hi, > > > > We are debugging a segfault of perf in ordered_events__free(). > > hi, > any backtrace or info on how to reproduce it?
Here is the backtrace: #0 0x0000000000500055 in ordered_events(float, long double,...)(...) () #1 0x0000000000500196 in ordered_events.reinit () #2 0x00000000004fe413 in perf_session.process_events () #3 0x0000000000440431 in cmd_record () #4 0x00000000004a439f in run_builtin () #5 0x000000000042b3e5 in main ()" > > > Disassemble shows the segfault was caused by oe->buff == NULL > > in the following line: > > > > /* > > * Current buffer might not have all the events allocated > > * yet, we need to free only allocated ones ... > > */ > > list_del(&oe->buffer->list); > > > > After poking around the code, I suspect it is caused by the following > > condition in alloc_event(): > > > > } else if (oe->buffer) { > > new = &oe->buffer->event[oe->buffer_idx]; > > if (++oe->buffer_idx == MAX_SAMPLE_BUFFER) > > oe->buffer = NULL; > > > argh.. yea, we need to check oe->buffer in ordered_events__free > > would attached change fix it for you? Let me try roll a fixed version to confirm. Thanks again! Song > > thanks, > jirka > > > --- > diff --git a/tools/perf/util/ordered-events.c > b/tools/perf/util/ordered-events.c > index 897589507d97..ea523d3b248f 100644 > --- a/tools/perf/util/ordered-events.c > +++ b/tools/perf/util/ordered-events.c > @@ -391,8 +391,10 @@ void ordered_events__free(struct ordered_events *oe) > * Current buffer might not have all the events allocated > * yet, we need to free only allocated ones ... > */ > - list_del(&oe->buffer->list); > - ordered_events_buffer__free(oe->buffer, oe->buffer_idx, oe); > + if (oe->buffer) { > + list_del(&oe->buffer->list); > + ordered_events_buffer__free(oe->buffer, oe->buffer_idx, oe); > + } > > /* ... and continue with the rest */ > list_for_each_entry_safe(buffer, tmp, &oe->to_free, list) {