Re: [BUG] perf: memory leak in perf top

[Arnaldo Carvalho de Melo]

Em Fri, Aug 05, 2016 at 06:58:12PM +0800, Wangnan (F) escreveu:
> perf top comsumes too much memory than it need.
> 
> Using following commands:
> 
>  # yes '' > /dev/null
>  # perf top -e raw_syscalls:sys_enter
> 
> System will quickly become unresponsive because of out of memory.
> 
> Using GDB I find two call stacks of malloc. See below.
> 
> [call stack 1]
> 
> #0 __GI___libc_malloc (bytes=140723951319552) at malloc.c:2841
> #1 0x00000000004b7246 in memdup (src=0x7f515e04b054, len=68) at
> ../lib/string.c:29
> #2 0x00000000004f9299 in hist_entry__init (sample_self=true,
> template=0x7ffcd9213a80, he=0xa37da50) at util/hist.c:401
> #3 hist_entry__new (template=template@entry=0x7ffcd9213a80
> <mailto:%28template=template@entry=0x7ffcd9213a80>,
> sample_self=sample_self@entry=true)
> <mailto:sample_self=sample_self@entry=true%29> at util/hist.c:458
> #4 0x00000000004fa13f in hists__findnew_entry (hists=0x3549d30,
> hists=0x3549d30, al=0x7ffcd9213ca0, sample_self=true, entry=0x
> 7ffcd9213a80) at util/hist.c:544
> #5 __hists__add_entry (hists=0x3549d30, al=0x7ffcd9213ca0,
> sym_parent=<optimized out>, bi=bi@entry=0x0 <mailto:bi=bi@entry=0x0>,
> mi=mi@entry=0x0 <mailto:mi=mi@entry=0x0>, sampl
> e=<optimized out>, sample_self=sample_self@entry=true
> <mailto:sample_self=sample_self@entry=true>, ops=ops@entry=0x0)
> <mailto:ops=ops@entry=0x0%29> at util/hist.c:600
> #6 0x00000000004fa3d6 in hists__add_entry (sample_self=true,
> sample=<optimized out>, mi=0x0, bi=0x0, sym_parent=<optimized out
> >, al=<optimized out>, hists=<optimized out>) at util/hist.c:611
> #7 iter_add_single_normal_entry (iter=0x7ffcd9213ce0, al=<optimized out>) at
> util/hist.c:823
> #8 0x00000000004fc3c5 in hist_entry_iter__add (iter=0x7ffcd9213ce0,
> al=0x7ffcd9213ca0, max_stack_depth=<optimized out>, arg=0x
> 7ffcd9214120) at util/hist.c:1030
> #9 0x00000000004536d7 in perf_event__process_sample (machine=<optimized
> out>, sample=0x7ffcd9213d30, evsel=0x3549bb0, event=<o
> ptimized out>, tool=0x7ffcd9214120) at builtin-top.c:800
> #10 perf_top__mmap_read_idx (top=top@entry=0x7ffcd9214120
> <mailto:%28top=top@entry=0x7ffcd9214120>, idx=idx@entry=0)
> <mailto:idx=idx@entry=0%29> at builtin-top.c:866
> #11 0x00000000004559fd in perf_top__mmap_read (top=0x7ffcd9214120) at
> builtin-top.c:883
> #12 __cmd_top (top=0x7ffcd9214120) at builtin-top.c:1018
> #13 cmd_top (argc=<optimized out>, argv=<optimized out>, prefix=<optimized
> out>) at builtin-top.c:1344
> #14 0x0000000000493561 in run_builtin (p=p@entry=0x948000
> <mailto:%28p=p@entry=0x948000> <commands+288>, argc=argc@entry=4
> <mailto:argc=argc@entry=4>, argv=argv@entry=0x7ffcd92199b0)
> <mailto:argv=argv@entry=0x7ffcd92199b0%29> at
> perf.c:357
> #15 0x0000000000437157 in handle_internal_command (argv=0x7ffcd92199b0,
> argc=4) at perf.c:419
> #16 run_argv (argv=0x7ffcd9219720, argcp=0x7ffcd921972c) at perf.c:465
> #17 main (argc=4, argv=0x7ffcd92199b0) at perf.c:609
> 
> [call stack 2]
 
> #0 __GI___libc_malloc (bytes=140723951319456) at malloc.c:2841
> #1 0x00000000005766de in trace_seq_init (s=0x7ffcd92139b0) at trace-seq.c:60
> #2 0x00000000004f7047 in get_trace_output (he=0x7ffcd9213a80) at
> util/sort.c:584

Yeah, this allocates 4K, way too much, can you try with this patch,
which amounts to a trace_seq_trim()?

diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
index 947d21f38398..37ddcf57500f 100644
--- a/tools/perf/util/sort.c
+++ b/tools/perf/util/sort.c
@@ -588,7 +588,7 @@ static char *get_trace_output(struct hist_entry *he)
 	} else {
 		pevent_event_info(&seq, evsel->tp_format, &rec);
 	}
-	return seq.buffer;
+	return realloc(seq.buffer, seq.len);
 }
 
 static int64_t
> #3 sort__trace_cmp (left=0x40e6d30, right=0x7ffcd9213a80) at util/sort.c:606
> #4 0x00000000004fa007 in hist_entry__cmp (right=0x7ffcd9213a80,
> left=0x40e6d30) at util/hist.c:1072
> #5 hists__findnew_entry (hists=0x3549d30, hists=0x3549d30,
> al=0x7ffcd9213ca0, sample_self=true, entry=0x7ffcd9213a80) at util/
> hist.c:509
> #6 __hists__add_entry (hists=0x3549d30, al=0x7ffcd9213ca0,
> sym_parent=<optimized out>, bi=bi@entry=0x0 <mailto:bi=bi@entry=0x0>,
> mi=mi@entry=0x0 <mailto:mi=mi@entry=0x0>, sampl
> e=<optimized out>, sample_self=sample_self@entry=true
> <mailto:sample_self=sample_self@entry=true>, ops=ops@entry=0x0)
> <mailto:ops=ops@entry=0x0%29> at util/hist.c:600
> #7 0x00000000004fa3d6 in hists__add_entry (sample_self=true,
> sample=<optimized out>, mi=0x0, bi=0x0, sym_parent=<optimized out
> >, al=<optimized out>, hists=<optimized out>) at util/hist.c:611
> #8 iter_add_single_normal_entry (iter=0x7ffcd9213ce0, al=<optimized out>) at
> util/hist.c:823
> #9 0x00000000004fc3c5 in hist_entry_iter__add (iter=0x7ffcd9213ce0,
> al=0x7ffcd9213ca0, max_stack_depth=<optimized out>, arg=0x
> 7ffcd9214120) at util/hist.c:1030
> #10 0x00000000004536d7 in perf_event__process_sample (machine=<optimized
> out>, sample=0x7ffcd9213d30, evsel=0x3549bb0, event=<o
> ptimized out>, tool=0x7ffcd9214120) at builtin-top.c:800
> #11 perf_top__mmap_read_idx (top=top@entry=0x7ffcd9214120
> <mailto:%28top=top@entry=0x7ffcd9214120>, idx=idx@entry=0)
> <mailto:idx=idx@entry=0%29> at builtin-top.c:866
> #12 0x00000000004559fd in perf_top__mmap_read (top=0x7ffcd9214120) at
> builtin-top.c:883
> #13 __cmd_top (top=0x7ffcd9214120) at builtin-top.c:1018
> #14 cmd_top (argc=<optimized out>, argv=<optimized out>, prefix=<optimized
> out>) at builtin-top.c:1344
> #15 0x0000000000493561 in run_builtin (p=p@entry=0x948000
> <mailto:%28p=p@entry=0x948000> <commands+288>, argc=argc@entry=4
> <mailto:argc=argc@entry=4>, argv=argv@entry=0x7ffcd92199b0)
> <mailto:argv=argv@entry=0x7ffcd92199b0%29> at
> perf.c:357
> #16 0x0000000000437157 in handle_internal_command (argv=0x7ffcd92199b0,
> argc=4) at perf.c:419
> #17 run_argv (argv=0x7ffcd9219720, argcp=0x7ffcd921972c) at perf.c:465
> #18 main (argc=4, argv=0x7ffcd92199b0) at perf.c:609