Messages in this thread | | | Date | Fri, 15 May 2015 11:08:04 +0900 | From | Namhyung Kim <> | Subject | Re: [GIT PULL 00/30] perf/core improvements and fixes |
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Hi Arnaldo,
On Thu, May 14, 2015 at 10:18:27AM -0300, Arnaldo Carvalho de Melo wrote: > Em Thu, May 14, 2015 at 05:23:30PM +0900, Namhyung Kim escreveu: > > On Mon, May 11, 2015 at 11:06:26AM -0300, Arnaldo Carvalho de Melo wrote: > > > Em Mon, May 11, 2015 at 02:09:39PM +0900, Namhyung Kim escreveu: > > > > I'm seeing a segfault on 'perf report' with a large data file after > > > > applying thread refcount change - it happens regardless of the atomic > > > > operation. > > > > Any specific 'perf record' command line? Does it take a long time to > > > reproduce? Any backtraces? I'll try to repro, its possible that we're > > > doing one too many thread__put()... > > > It's a kernel build with '-j 20' and recorded data size is ~2.1GB. > > It takes ~30 sec to reproduce. > > > > $ perf report -i threaded/kbuild7.data --header-only > > # ======== > > # captured on: Thu Dec 18 12:06:35 2014 > > # hostname : sejong > > # os release : 3.17.4-1-ARCH > > # perf version : 3.18.rc3.gcb4774b > > # arch : x86_64 > > # nrcpus online : 12 > > # nrcpus avail : 12 > > # cpudesc : Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz > > # cpuid : GenuineIntel,6,45,7 > > # total memory : 24646828 kB > > # cmdline : /home/namhyung/project/linux/tools/perf/perf record -ag -o /home/namhyung/tmp/perf/threaded/kbuild7.data -- make -j20 > > # event : name = cycles, , size = 104, { sample_period, sample_freq } = 4000, sample_type = IP|TID|TIME|CALLCHAIN|CPU|PERIOD, disabled = 1, inherit > > # HEADER_CPU_TOPOLOGY info available, use -I to display > > # HEADER_NUMA_TOPOLOGY info available, use -I to display > > # pmu mappings: cpu = 4, software = 1, power = 24, uncore_pcu = 13, tracepoint = 2, uncore_imc_0 = 15, uncore_imc_1 = 16, uncore_imc_2 = 17, uncore_ > > # ======== > > # > > > > > > $ perf data stat -i threaded/kbuild7.data > > > > Total event stats for 'threaded/kbuild7.data' file: > > > > TOTAL events: 25126492 > > MMAP events: 114 > > COMM events: 117957 > > EXIT events: 240544 > > THROTTLE events: 16 > > UNTHROTTLE events: 16 > > FORK events: 120488 > > SAMPLE events: 23878219 > > MMAP2 events: 745325 > > FINISHED_ROUND events: 23813 > > > > Sample event stats: > > > > 20,579,564,471,104 cycles > > 23,878,219 samples # sampling ratio 99.745% (3989/4000) > > > > 498.736917889 second time sampled > > > > > > $ perf report -i threaded/kbuild7.data > > We need to improve this segfault backtrace, I have to always use > addr2line to resolve those missing entries, i.e. if you try: > > addr2line -fe /path/to/your/perf 0x4dd9c8 > addr2line -fe /path/to/your/perf 0x4e2580 > > We would have resolved those lines :-/
Right, I'll add it to my TODO list.
Anyway, this is a backtrace using gdb..
Thanks, Namhyung
Program received signal SIGSEGV, Segmentation fault. 0x00007ffff5fb229e in __strcmp_sse2_unaligned () from /usr/lib/libc.so.6 (gdb) bt #0 0x00007ffff5fb229e in __strcmp_sse2_unaligned () from /usr/lib/libc.so.6 #1 0x00000000004d3948 in _sort__dso_cmp (map_r=<optimized out>, map_l=<optimized out>) at util/sort.c:142 #2 sort__dso_cmp (left=<optimized out>, right=<optimized out>) at util/sort.c:148 #3 0x00000000004d7f08 in hist_entry__cmp (right=0x7fffffffc530, left=0x323a27f0) at util/hist.c:911 #4 add_hist_entry (sample_self=true, al=0x7fffffffc710, entry=0x7fffffffc530, hists=0x18f6690) at util/hist.c:389 #5 __hists__add_entry (hists=0x18f6690, al=0x7fffffffc710, sym_parent=<optimized out>, bi=bi@entry=0x0, mi=mi@entry=0x0, period=<optimized out>, weight=0, transaction=0, sample_self=true) at util/hist.c:471 #6 0x00000000004d8234 in iter_add_single_normal_entry (iter=0x7fffffffc740, al=<optimized out>) at util/hist.c:662 #7 0x00000000004d8765 in hist_entry_iter__add (iter=0x7fffffffc740, al=0x7fffffffc710, evsel=0x18f6550, sample=<optimized out>, max_stack_depth=<optimized out>, arg=0x7fffffffd0a0) at util/hist.c:871 #8 0x0000000000436353 in process_sample_event (tool=0x7fffffffd0a0, event=<optimized out>, sample=0x7fffffffc870, evsel=0x18f6550, machine=<optimized out>) at builtin-report.c:171 #9 0x00000000004bbe23 in perf_evlist__deliver_sample (machine=0x18f4cc0, evsel=0x18f6550, sample=0x7fffffffc870, event=0x7fffe0bd3220, tool=0x7fffffffd0a0, evlist=0x18f5b50) at util/session.c:972 #10 machines__deliver_event (machines=machines@entry=0x18f4cc0, evlist=<optimized out>, event=event@entry=0x7fffe0bd3220, sample=sample@entry=0x7fffffffc870, tool=tool@entry=0x7fffffffd0a0, file_offset=file_offset@entry=1821434400) at util/session.c:1009 #11 0x00000000004bc681 in perf_session__deliver_event (file_offset=1821434400, tool=0x7fffffffd0a0, sample=0x7fffffffc870, event=0x7fffe0bd3220, session=<optimized out>) at util/session.c:1050 #12 ordered_events__deliver_event (oe=0x18f4e00, event=<optimized out>) at util/session.c:109 #13 0x00000000004bf12b in __ordered_events__flush (oe=0x18f4e00) at util/ordered-events.c:207 #14 ordered_events__flush (oe=0x18f4e00, how=OE_FLUSH__ROUND) at util/ordered-events.c:271 #15 0x00000000004bc8aa in perf_session__process_user_event (file_offset=1821919744, event=0x7fffe0c49a00, session=0x18f4c00) at util/session.c:1087 #16 perf_session__process_event (session=session@entry=0x18f4c00, event=event@entry=0x7fffe0c49a00, file_offset=file_offset@entry=1821919744) at util/session.c:1200 #17 0x00000000004bdcd0 in __perf_session__process_events (file_size=2160054608, data_size=<optimized out>, data_offset=<optimized out>, session=0x18f4c00) at util/session.c:1501 #18 perf_session__process_events (session=session@entry=0x18f4c00) at util/session.c:1548 #19 0x0000000000437609 in __cmd_report (rep=0x7fffffffd0a0) at builtin-report.c:487 #20 cmd_report (argc=0, argv=0x7fffffffe8d0, prefix=<optimized out>) at builtin-report.c:878 #21 0x000000000047de33 in run_builtin (p=p@entry=0x85a6e8 <commands+168>, argc=argc@entry=6, argv=argv@entry=0x7fffffffe8d0) at perf.c:370 #22 0x000000000042893a in handle_internal_command (argv=0x7fffffffe8d0, argc=6) at perf.c:429 #23 run_argv (argv=0x7fffffffe660, argcp=0x7fffffffe66c) at perf.c:473 #24 main (argc=6, argv=0x7fffffffe8d0) at perf.c:588
> > But I think this is a longstanding bug in handling hist_entries, i.e. > probably we have more than one pointer to a hist_entry and are accessing > it in two places at the same time, with one of them deleting it and > possibly reusing the data. > > > perf: Segmentation fault > > -------- backtrace -------- > > perf[0x51c7cb] > > /usr/lib/libc.so.6(+0x33540)[0x7f37eb37e540] > > /usr/lib/libc.so.6(+0x9029e)[0x7f37eb3db29e] > > perf[0x4dd9c8] > > perf(__hists__add_entry+0x188)[0x4e2258] > > perf[0x4e2580] > > perf(hist_entry_iter__add+0x9d)[0x4e2a7d] > > perf[0x437fda] > > perf[0x4c4c8e] > > perf[0x4c5176] > > perf[0x4c8bab] > > perf[0x4c53c2] > > perf[0x4c5f0c] > > perf(perf_session__process_events+0xb3)[0x4c6b23] > > perf(cmd_report+0x12a0)[0x439310] > > perf[0x483ec3] > > perf(main+0x60a)[0x42979a] > > /usr/lib/libc.so.6(__libc_start_main+0xf0)[0x7f37eb36b800] > > perf(_start+0x29)[0x4298b9] > > [0x0] > > > > It seems like some memory area was corrupted.. > > Right, looks like use after free, for instance, freeing something still > on a list or rbtree :-/ > > - Arnaldo > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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