On Fri, Feb 16, 2018 at 08:53:04AM +0100, Jiri Olsa wrote: > On Fri, Feb 16, 2018 at 10:25:31AM +0800, Jin, Yao wrote: > > SNIP > > > > From my opinion, the option '--max-stack' in perf report looks not very > > > necessary. While it's just my personal opinion, need to hear from more > > > people. :) > > > > > > Thanks > > > Jin Yao > > > > > > > thanks, > > > > jirka > > > > > > > > > > > > --- > > > > diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c > > > > index b6140950301e..b50b7b70dcca 100644 > > > > --- a/tools/perf/util/hist.c > > > > +++ b/tools/perf/util/hist.c > > > > @@ -879,7 +879,7 @@ iter_prepare_cumulative_entry(struct > > > > hist_entry_iter *iter, > > > > * cumulated only one time to prevent entries more than 100% > > > > * overhead. > > > > */ > > > > - he_cache = malloc(sizeof(*he_cache) * (iter->max_stack + 1)); > > > > + he_cache = malloc(sizeof(*he_cache) * (callchain_cursor.nr + 1)); > > > > if (he_cache == NULL) > > > > return -ENOMEM; > > > > > > > > Hi Jiri, > > > > I guess you will post this patch, right? > > yep, later today
here it is.. I think we want this change now to fix the crash, and some more fixes later to ensure that the branch stack code follows properly the logic of --max-stack, which is not the case now thanks, jirka --- Jin Yao reported memory corrupton in perf report with branch info used for stack trace: > Following command lines will cause perf crash. > perf record -j call -g -a <application> > perf report --branch-history > > *** Error in `perf': double free or corruption (!prev): 0x00000000104aa040 *** > ======= Backtrace: ========= > /lib/x86_64-linux-gnu/libc.so.6(+0x77725)[0x7f6b37254725] > /lib/x86_64-linux-gnu/libc.so.6(+0x7ff4a)[0x7f6b3725cf4a] > /lib/x86_64-linux-gnu/libc.so.6(cfree+0x4c)[0x7f6b37260abc] > perf[0x51b914] > perf(hist_entry_iter__add+0x1e5)[0x51f305] > perf[0x43cf01] > perf[0x4fa3bf] > perf[0x4fa923] > perf[0x4fd396] > perf[0x4f9614] > perf(perf_session__process_events+0x89e)[0x4fc38e] > perf(cmd_report+0x15d2)[0x43f202] > perf[0x4a059f] > perf(main+0x631)[0x427b71] > /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f6b371fd830] > perf(_start+0x29)[0x427d89] For the cumulative output, we allocate he_cache array based on the --max-stack option value and populate it with data from callchain_cursor. The --max-stack option value does not ensure now the limit for number of callchain_cursor nodes, so the cumulative iter code will allocate smaller array than it's actually needed and cause above corruption. I think the --max-stack limit does not apply here anyway, because we add callchain data as normal hist entries, while the --max-stack control the limit of single entry callchain depth. Using the callchain_cursor.nr as he_cache array count to fix this. Also removing struct hist_entry_iter::max_stack, because there's no longer any use for it. We need more fixes to ensure that the branch stack code follows properly the logic of --max-stack, which is not the case at the moment. Reported-by: Jin Yao <yao....@linux.intel.com> Original-patch-by: Jin Yao <yao....@linux.intel.com> Link: http://lkml.kernel.org/n/tip-qj1kdpvyu25ac6w22lhmy...@git.kernel.org Signed-off-by: Jiri Olsa <jo...@kernel.org> --- tools/perf/util/hist.c | 4 +--- tools/perf/util/hist.h | 1 - 2 files changed, 1 insertion(+), 4 deletions(-) diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c index b6140950301e..44a8456cea10 100644 --- a/tools/perf/util/hist.c +++ b/tools/perf/util/hist.c @@ -879,7 +879,7 @@ iter_prepare_cumulative_entry(struct hist_entry_iter *iter, * cumulated only one time to prevent entries more than 100% * overhead. */ - he_cache = malloc(sizeof(*he_cache) * (iter->max_stack + 1)); + he_cache = malloc(sizeof(*he_cache) * (callchain_cursor.nr + 1)); if (he_cache == NULL) return -ENOMEM; @@ -1045,8 +1045,6 @@ int hist_entry_iter__add(struct hist_entry_iter *iter, struct addr_location *al, if (err) return err; - iter->max_stack = max_stack_depth; - err = iter->ops->prepare_entry(iter, al); if (err) goto out; diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h index 02721b579746..e869cad4d89f 100644 --- a/tools/perf/util/hist.h +++ b/tools/perf/util/hist.h @@ -107,7 +107,6 @@ struct hist_entry_iter { int curr; bool hide_unresolved; - int max_stack; struct perf_evsel *evsel; struct perf_sample *sample; -- 2.13.6
