* perf segfault in in ordered_events__free()
@ 2019-01-16 18:57 Song Liu
2019-01-16 21:34 ` Jiri Olsa
0 siblings, 1 reply; 5+ messages in thread
From: Song Liu @ 2019-01-16 18:57 UTC (permalink / raw)
To: open list, Jiri Olsa; +Cc: acme
Hi,
We are debugging a segfault of perf in ordered_events__free().
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;
Does this theory make sense? If so, what would be the best fix?
Thanks in advance!
Song
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: perf segfault in in ordered_events__free() 2019-01-16 18:57 perf segfault in in ordered_events__free() Song Liu @ 2019-01-16 21:34 ` Jiri Olsa 2019-01-16 21:53 ` Song Liu 0 siblings, 1 reply; 5+ messages in thread From: Jiri Olsa @ 2019-01-16 21:34 UTC (permalink / raw) To: Song Liu; +Cc: open list, Jiri Olsa, acme 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? > 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? 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) { ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: perf segfault in in ordered_events__free() 2019-01-16 21:34 ` Jiri Olsa @ 2019-01-16 21:53 ` Song Liu 2019-01-17 7:33 ` Song Liu 0 siblings, 1 reply; 5+ messages in thread From: Song Liu @ 2019-01-16 21:53 UTC (permalink / raw) To: Jiri Olsa; +Cc: open list, Jiri Olsa, acme Thanks Jiri! On Wed, Jan 16, 2019 at 1:34 PM Jiri Olsa <jolsa@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) { ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: perf segfault in in ordered_events__free() 2019-01-16 21:53 ` Song Liu @ 2019-01-17 7:33 ` Song Liu 2019-01-17 9:18 ` Jiri Olsa 0 siblings, 1 reply; 5+ messages in thread From: Song Liu @ 2019-01-17 7:33 UTC (permalink / raw) To: Jiri Olsa; +Cc: open list, Jiri Olsa, acme On Wed, Jan 16, 2019 at 1:53 PM Song Liu <liu.song.a23@gmail.com> wrote: > > Thanks Jiri! > > On Wed, Jan 16, 2019 at 1:34 PM Jiri Olsa <jolsa@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. Yes, the patch fixes this segfault. Please CC me on the official patch to back port the official version. Thanks, Song ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: perf segfault in in ordered_events__free() 2019-01-17 7:33 ` Song Liu @ 2019-01-17 9:18 ` Jiri Olsa 0 siblings, 0 replies; 5+ messages in thread From: Jiri Olsa @ 2019-01-17 9:18 UTC (permalink / raw) To: Song Liu; +Cc: open list, Jiri Olsa, acme On Wed, Jan 16, 2019 at 11:33:55PM -0800, Song Liu wrote: > On Wed, Jan 16, 2019 at 1:53 PM Song Liu <liu.song.a23@gmail.com> wrote: > > > > Thanks Jiri! > > > > On Wed, Jan 16, 2019 at 1:34 PM Jiri Olsa <jolsa@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. > > Yes, the patch fixes this segfault. Please CC me on the official patch to > back port the official version. thanks for testing, will post it today jirka ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-01-17 9:18 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-01-16 18:57 perf segfault in in ordered_events__free() Song Liu 2019-01-16 21:34 ` Jiri Olsa 2019-01-16 21:53 ` Song Liu 2019-01-17 7:33 ` Song Liu 2019-01-17 9:18 ` Jiri Olsa
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