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perf record: Fix memory leak in vDSO

PATCH Applied Namhyung Kim 3 participants 6 messages Mar 15, 2021 – Mar 24, 2021 perf events

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Namhyung Kim

author maintainer
#0 lore raw

PATCH 1/1 perf record: Fix memory leak in vDSO

I got several memory leak reports from Asan with a simple command. It was because VDSO is not released due to the refcount. Like in __dsos_addnew_id(), it should put the refcount after adding to the list.

  $ perf record true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.030 MB perf.data (10 samples) ]

=================================================================
==692599==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 439 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce4aa8ee in dso__new_id util/dso.c:1256
    #2 0x559bce59245a in __machine__addnew_vdso util/vdso.c:132
    #3 0x559bce59245a in machine__findnew_vdso util/vdso.c:347
    #4 0x559bce50826c in map__new util/map.c:175
    #5 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #6 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #7 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #8 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #9 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #10 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #11 0x559bce519bea in perf_session__process_events util/session.c:2297
    #12 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #13 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #14 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #15 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #16 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #17 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #18 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #19 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #20 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

Indirect leak of 32 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce520907 in nsinfo__copy util/namespaces.c:169
    #2 0x559bce50821b in map__new util/map.c:168
    #3 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #4 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #5 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #6 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #7 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #8 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #9 0x559bce519bea in perf_session__process_events util/session.c:2297
    #10 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #11 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #12 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #13 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #14 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #15 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #16 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #17 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #18 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: 471 byte(s) leaked in 2 allocation(s).

Signed-off-by Namhyung Kim <[email protected]>
---
 tools/perf/util/vdso.c | 2 ++
 1 file changed, 2 insertions(+)
tools/perf/util/vdso.c +2 -0
index 3cc91ad048ea..43beb169631d 100644
@@ -133,6 +133,8 @@ static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s
 	if (dso != NULL) {
 		__dsos__add(&machine->dsos, dso);
 		dso__set_long_name(dso, long_name, false);
+		/* Put dso here because __dsos_add already got it */
+		dso__put(dso);
 	}
 
 	return dso;
Signature · 1 line
2.31.0.rc2.261.g7f71774620-goog
#1 lore raw
Quoted 67 lines · Namhyung Kim

I got several memory leak reports from Asan with a simple command. It was because VDSO is not released due to the refcount. Like in __dsos_addnew_id(), it should put the refcount after adding to the list.

  $ perf record true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.030 MB perf.data (10 samples) ]

=================================================================
==692599==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 439 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce4aa8ee in dso__new_id util/dso.c:1256
    #2 0x559bce59245a in __machine__addnew_vdso util/vdso.c:132
    #3 0x559bce59245a in machine__findnew_vdso util/vdso.c:347
    #4 0x559bce50826c in map__new util/map.c:175
    #5 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #6 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #7 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #8 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #9 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #10 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #11 0x559bce519bea in perf_session__process_events util/session.c:2297
    #12 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #13 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #14 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #15 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #16 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #17 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #18 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #19 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #20 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

Indirect leak of 32 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce520907 in nsinfo__copy util/namespaces.c:169
    #2 0x559bce50821b in map__new util/map.c:168
    #3 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #4 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #5 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #6 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #7 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #8 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #9 0x559bce519bea in perf_session__process_events util/session.c:2297
    #10 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #11 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #12 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #13 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #14 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #15 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #16 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #17 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #18 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: 471 byte(s) leaked in 2 allocation(s).

Signed-off-by Namhyung Kim <[email protected]>
---
 tools/perf/util/vdso.c | 2 ++
 1 file changed, 2 insertions(+)
tools/perf/util/vdso.c +0 -0
index 3cc91ad048ea..43beb169631d 100644

tools/perf/util/vdso.c static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s · line 137

Quoted 5 lines
tools/perf/util/vdso.c +2 -0
@@ -133,6 +133,8 @@ static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s
 	if (dso != NULL) {
 		__dsos__add(&machine->dsos, dso);
 		dso__set_long_name(dso, long_name, false);
+		/* Put dso here because __dsos_add already got it */
+		dso__put(dso);

from quick look I don't understand why we take refcnt down right after adding to the list.. it would make sense to me if dso is not stored elsewhere so we want dsos__exit to release it.. but it's still stored in map object

I checked and we do extra dso__get in machine__findnew_vdso (and also in dsos__findnew_id) ... so that one seems to me like the one we should remove

but I might be missing something, I'll try to check more deeply later on

jirka

author maintainer
#2 lore raw
Quoted 80 lines · Jiri Olsa
Quoted 67 lines · Namhyung Kim

I got several memory leak reports from Asan with a simple command. It was because VDSO is not released due to the refcount. Like in __dsos_addnew_id(), it should put the refcount after adding to the list.

  $ perf record true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.030 MB perf.data (10 samples) ]

=================================================================
==692599==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 439 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce4aa8ee in dso__new_id util/dso.c:1256
    #2 0x559bce59245a in __machine__addnew_vdso util/vdso.c:132
    #3 0x559bce59245a in machine__findnew_vdso util/vdso.c:347
    #4 0x559bce50826c in map__new util/map.c:175
    #5 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #6 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #7 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #8 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #9 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #10 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #11 0x559bce519bea in perf_session__process_events util/session.c:2297
    #12 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #13 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #14 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #15 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #16 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #17 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #18 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #19 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #20 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

Indirect leak of 32 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce520907 in nsinfo__copy util/namespaces.c:169
    #2 0x559bce50821b in map__new util/map.c:168
    #3 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #4 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #5 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #6 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #7 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #8 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #9 0x559bce519bea in perf_session__process_events util/session.c:2297
    #10 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #11 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #12 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #13 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #14 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #15 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #16 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #17 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #18 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: 471 byte(s) leaked in 2 allocation(s).

Signed-off-by Namhyung Kim <[email protected]>
---
 tools/perf/util/vdso.c | 2 ++
 1 file changed, 2 insertions(+)
tools/perf/util/vdso.c +0 -0
index 3cc91ad048ea..43beb169631d 100644

tools/perf/util/vdso.c static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s · line 137

Quoted 5 lines
tools/perf/util/vdso.c +2 -0
@@ -133,6 +133,8 @@ static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s
      if (dso != NULL) {
              __dsos__add(&machine->dsos, dso);
              dso__set_long_name(dso, long_name, false);
+             /* Put dso here because __dsos_add already got it */
+             dso__put(dso);

from quick look I don't understand why we take refcnt down right after adding to the list.. it would make sense to me if dso is not stored elsewhere so we want dsos__exit to release it.. but it's still stored in map object

Quoted 6 lines

I checked and we do extra dso__get in machine__findnew_vdso (and also in dsos__findnew_id) ... so that one seems to me like the one we should remove

but I might be missing something, I'll try to check more deeply later on

I think we assume the find/findnew APIs include increment of the refcount, otherwise all callers should be converted to do it explicitly.

Then the 'find' part should increase it but the 'new' part is not (as it already has 2) and that's why we have that.

Thanks,
Namhyung

maintainer
#3 lore raw

Em Tue, Mar 16, 2021 at 11:28:12AM +0900, Namhyung Kim escreveu:

Quoted 65 lines · Jiri Olsa
Quoted 64 lines · Namhyung Kim
Quoted 62 lines

I got several memory leak reports from Asan with a simple command. It was because VDSO is not released due to the refcount. Like in __dsos_addnew_id(), it should put the refcount after adding to the list.

  $ perf record true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.030 MB perf.data (10 samples) ]

=================================================================
==692599==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 439 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce4aa8ee in dso__new_id util/dso.c:1256
    #2 0x559bce59245a in __machine__addnew_vdso util/vdso.c:132
    #3 0x559bce59245a in machine__findnew_vdso util/vdso.c:347
    #4 0x559bce50826c in map__new util/map.c:175
    #5 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #6 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #7 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #8 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #9 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #10 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #11 0x559bce519bea in perf_session__process_events util/session.c:2297
    #12 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #13 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #14 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #15 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #16 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #17 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #18 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #19 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #20 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

Indirect leak of 32 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce520907 in nsinfo__copy util/namespaces.c:169
    #2 0x559bce50821b in map__new util/map.c:168
    #3 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #4 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #5 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #6 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #7 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #8 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #9 0x559bce519bea in perf_session__process_events util/session.c:2297
    #10 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #11 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #12 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #13 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #14 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #15 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #16 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #17 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #18 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: 471 byte(s) leaked in 2 allocation(s).

Signed-off-by Namhyung Kim <[email protected]>
---
 tools/perf/util/vdso.c | 2 ++
 1 file changed, 2 insertions(+)
Quoted 13 lines
Quoted 5 lines
Quoted 5 lines
tools/perf/util/vdso.c +0 -0
index 3cc91ad048ea..43beb169631d 100644
@@ -133,6 +133,8 @@ static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s
Quoted 8 lines

tools/perf/util/vdso.c static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s · line 137

Quoted 5 lines
tools/perf/util/vdso.c +2 -0
      if (dso != NULL) {
              __dsos__add(&machine->dsos, dso);
              dso__set_long_name(dso, long_name, false);
+             /* Put dso here because __dsos_add already got it */
+             dso__put(dso);

from quick look I don't understand why we take refcnt down right after adding to the list.. it would make sense to me

That is the right pattern, i.e. the list has a reference to it, if it is removed outside the __dsos__add(), then list traversal may be corrupted.

Quoted 6 lines
Quoted 6 lines

if dso is not stored elsewhere so we want dsos__exit to release it.. but it's still stored in map object

I checked and we do extra dso__get in machine__findnew_vdso (and also in dsos__findnew_id) ... so that one seems to me like the one we should remove

findnew _needs_ to grab te refcount while holding the lock, so that what it returns won't go away in a different thread.

Quoted 6 lines
Quoted 2 lines

but I might be missing something, I'll try to check more deeply later on

I think we assume the find/findnew APIs include increment of the refcount, otherwise all callers should be converted to do it explicitly.

The callers can't grab the reference safely, i.e. its outside the lock.

Quoted 5 lines

Then the 'find' part should increase it but the 'new' part is not (as it already has 2) and that's why we have that.

Thanks,
Namhyung

Signature · 1 line
- Arnaldo
Acked-by
#4 lore raw
Quoted 93 lines · Arnaldo Carvalho de Melo

Em Tue, Mar 16, 2021 at 11:28:12AM +0900, Namhyung Kim escreveu:

Quoted 65 lines · Jiri Olsa
Quoted 64 lines · Namhyung Kim
Quoted 62 lines

I got several memory leak reports from Asan with a simple command. It was because VDSO is not released due to the refcount. Like in __dsos_addnew_id(), it should put the refcount after adding to the list.

  $ perf record true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.030 MB perf.data (10 samples) ]

=================================================================
==692599==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 439 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce4aa8ee in dso__new_id util/dso.c:1256
    #2 0x559bce59245a in __machine__addnew_vdso util/vdso.c:132
    #3 0x559bce59245a in machine__findnew_vdso util/vdso.c:347
    #4 0x559bce50826c in map__new util/map.c:175
    #5 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #6 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #7 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #8 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #9 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #10 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #11 0x559bce519bea in perf_session__process_events util/session.c:2297
    #12 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #13 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #14 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #15 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #16 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #17 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #18 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #19 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #20 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

Indirect leak of 32 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce520907 in nsinfo__copy util/namespaces.c:169
    #2 0x559bce50821b in map__new util/map.c:168
    #3 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #4 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #5 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #6 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #7 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #8 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #9 0x559bce519bea in perf_session__process_events util/session.c:2297
    #10 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #11 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #12 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #13 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #14 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #15 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #16 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #17 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #18 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: 471 byte(s) leaked in 2 allocation(s).

Signed-off-by Namhyung Kim <[email protected]>
---
 tools/perf/util/vdso.c | 2 ++
 1 file changed, 2 insertions(+)
Quoted 13 lines
Quoted 5 lines
Quoted 5 lines
tools/perf/util/vdso.c +0 -0
index 3cc91ad048ea..43beb169631d 100644
@@ -133,6 +133,8 @@ static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s
Quoted 8 lines

tools/perf/util/vdso.c static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s · line 137

Quoted 5 lines
tools/perf/util/vdso.c +2 -0
      if (dso != NULL) {
              __dsos__add(&machine->dsos, dso);
              dso__set_long_name(dso, long_name, false);
+             /* Put dso here because __dsos_add already got it */
+             dso__put(dso);

from quick look I don't understand why we take refcnt down right after adding to the list.. it would make sense to me

That is the right pattern, i.e. the list has a reference to it, if it is removed outside the __dsos__add(), then list traversal may be corrupted.

Quoted 6 lines
Quoted 6 lines

if dso is not stored elsewhere so we want dsos__exit to release it.. but it's still stored in map object

I checked and we do extra dso__get in machine__findnew_vdso (and also in dsos__findnew_id) ... so that one seems to me like the one we should remove

findnew _needs_ to grab te refcount while holding the lock, so that what it returns won't go away in a different thread.

Quoted 11 lines
Quoted 6 lines
Quoted 2 lines

but I might be missing something, I'll try to check more deeply later on

I think we assume the find/findnew APIs include increment of the refcount, otherwise all callers should be converted to do it explicitly.

The callers can't grab the reference safely, i.e. its outside the lock.

Quoted 2 lines

Then the 'find' part should increase it but the 'new' part is not (as it already has 2) and that's why we have that.

map__new
{
machine__findnew_vdso

  {
    __machine__addnew_vdso
    {
      dso__new                      refcnt=1
      __dsos__add                   refcnt=2
      dso__put                      refcnt=1
    }
    dso__get                        refcnt=2

}
map__init refcnt=3
dso__put refcnt=2
}

we end up with refcnt=2, which is fine, because there's dsos list and map owners but the process is tricky ;-)

anyway I'm ok with the change

Acked-by Jiri Olsa <[email protected]>

thanks,
jirka

maintainer Applied
#5 lore raw

Em Tue, Mar 16, 2021 at 02:50:48PM +0100, Jiri Olsa escreveu:

Quoted 122 lines · Arnaldo Carvalho de Melo
Quoted 93 lines

Em Tue, Mar 16, 2021 at 11:28:12AM +0900, Namhyung Kim escreveu:

Quoted 65 lines · Jiri Olsa
Quoted 64 lines · Namhyung Kim
Quoted 62 lines

I got several memory leak reports from Asan with a simple command. It was because VDSO is not released due to the refcount. Like in __dsos_addnew_id(), it should put the refcount after adding to the list.

  $ perf record true
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.030 MB perf.data (10 samples) ]

=================================================================
==692599==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 439 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce4aa8ee in dso__new_id util/dso.c:1256
    #2 0x559bce59245a in __machine__addnew_vdso util/vdso.c:132
    #3 0x559bce59245a in machine__findnew_vdso util/vdso.c:347
    #4 0x559bce50826c in map__new util/map.c:175
    #5 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #6 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #7 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #8 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #9 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #10 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #11 0x559bce519bea in perf_session__process_events util/session.c:2297
    #12 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #13 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #14 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #15 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #16 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #17 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #18 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #19 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #20 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

Indirect leak of 32 byte(s) in 1 object(s) allocated from:

    #0 0x7fea52341037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x559bce520907 in nsinfo__copy util/namespaces.c:169
    #2 0x559bce50821b in map__new util/map.c:168
    #3 0x559bce503c92 in machine__process_mmap2_event util/machine.c:1787
    #4 0x559bce512f6b in machines__deliver_event util/session.c:1481
    #5 0x559bce515107 in perf_session__deliver_event util/session.c:1551
    #6 0x559bce51d4d2 in do_flush util/ordered-events.c:244
    #7 0x559bce51d4d2 in __ordered_events__flush util/ordered-events.c:323
    #8 0x559bce519bea in __perf_session__process_events util/session.c:2268
    #9 0x559bce519bea in perf_session__process_events util/session.c:2297
    #10 0x559bce2e7a52 in process_buildids /home/namhyung/project/linux/tools/perf/builtin-record.c:1017
    #11 0x559bce2e7a52 in record__finish_output /home/namhyung/project/linux/tools/perf/builtin-record.c:1234
    #12 0x559bce2ed4f6 in __cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2026
    #13 0x559bce2ed4f6 in cmd_record /home/namhyung/project/linux/tools/perf/builtin-record.c:2858
    #14 0x559bce422db4 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:313
    #15 0x559bce2acac8 in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:365
    #16 0x559bce2acac8 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:409
    #17 0x559bce2acac8 in main /home/namhyung/project/linux/tools/perf/perf.c:539
    #18 0x7fea51e76d09 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: 471 byte(s) leaked in 2 allocation(s).

Signed-off-by Namhyung Kim <[email protected]>
---
 tools/perf/util/vdso.c | 2 ++
 1 file changed, 2 insertions(+)
Quoted 13 lines
Quoted 5 lines
Quoted 5 lines
tools/perf/util/vdso.c +0 -0
index 3cc91ad048ea..43beb169631d 100644
@@ -133,6 +133,8 @@ static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s
Quoted 8 lines

tools/perf/util/vdso.c static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s · line 137

Quoted 5 lines
tools/perf/util/vdso.c +2 -0
      if (dso != NULL) {
              __dsos__add(&machine->dsos, dso);
              dso__set_long_name(dso, long_name, false);
+             /* Put dso here because __dsos_add already got it */
+             dso__put(dso);

from quick look I don't understand why we take refcnt down right after adding to the list.. it would make sense to me

That is the right pattern, i.e. the list has a reference to it, if it is removed outside the __dsos__add(), then list traversal may be corrupted.

Quoted 6 lines
Quoted 6 lines

if dso is not stored elsewhere so we want dsos__exit to release it.. but it's still stored in map object

I checked and we do extra dso__get in machine__findnew_vdso (and also in dsos__findnew_id) ... so that one seems to me like the one we should remove

findnew _needs_ to grab te refcount while holding the lock, so that what it returns won't go away in a different thread.

Quoted 11 lines
Quoted 6 lines
Quoted 2 lines

but I might be missing something, I'll try to check more deeply later on

I think we assume the find/findnew APIs include increment of the refcount, otherwise all callers should be converted to do it explicitly.

The callers can't grab the reference safely, i.e. its outside the lock.

Quoted 2 lines

Then the 'find' part should increase it but the 'new' part is not (as it already has 2) and that's why we have that.

map__new
{
machine__findnew_vdso

  {
    __machine__addnew_vdso
    {
      dso__new                      refcnt=1
      __dsos__add                   refcnt=2
      dso__put                      refcnt=1
    }
    dso__get                        refcnt=2

}
map__init refcnt=3
dso__put refcnt=2
}

Quoted 6 lines

we end up with refcnt=2, which is fine, because there's dsos list and map owners but the process is tricky ;-)

anyway I'm ok with the change

Acked-by Jiri Olsa <[email protected]>

Thanks, applied.

- Arnaldo