We received an error report that perf-record caused 'Segmentation fault'
on a newly system (e.g. on the new installed ubuntu).
(gdb) backtrace
#0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
#1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
#2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
#3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
#4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
#5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
The root cause is, evlist__add_bpf_sb_event() just returns 0 if
HAVE_LIBBPF_SUPPORT is not defined (inline function path). So it will
not create a valid evsel for side-band event.
But perf-record still creates BPF side band thread to process the
side-band event, then the error happpens.
We can reproduce this issue by removing the libelf-dev. e.g.
1. apt-get remove libelf-dev
2. perf record -a -- sleep 1
root@test:~# ./perf record -a -- sleep 1
perf: Segmentation fault
Obtained 6 stack frames.
./perf(+0x28eee8) [0x5562d6ef6ee8]
/lib/x86_64-linux-gnu/libc.so.6(+0x46210) [0x7fbfdc65f210]
./perf(+0x342e74) [0x5562d6faae74]
./perf(+0x257e39) [0x5562d6ebfe39]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x9609) [0x7fbfdc990609]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7fbfdc73b103]
Segmentation fault (core dumped)
To fix this issue,
1. We either install the missing libraries to let HAVE_LIBBPF_SUPPORT
be defined.
e.g. apt-get install libelf-dev and install other related libraries.
2. Use this patch to skip the side-band event setup if HAVE_LIBBPF_SUPPORT
is not set.
Signed-off-by: Jin Yao <[email protected]>
---
tools/perf/builtin-record.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index b6bdccd875bc..ae97f98e2753 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1506,6 +1506,7 @@ static int record__synthesize(struct record *rec, bool tail)
return err;
}
+#ifdef HAVE_LIBBPF_SUPPORT
static int record__process_signal_event(union perf_event *event __maybe_unused, void *data)
{
struct record *rec = data;
@@ -1550,6 +1551,12 @@ static int record__setup_sb_evlist(struct record *rec)
return 0;
}
+#else
+static int record__setup_sb_evlist(struct record *rec __maybe_unused)
+{
+ return 0;
+}
+#endif
static int __cmd_record(struct record *rec, int argc, const char **argv)
{
--
2.17.1
On Wed, Aug 05, 2020 at 10:29:37AM +0800, Jin Yao wrote:
> We received an error report that perf-record caused 'Segmentation fault'
> on a newly system (e.g. on the new installed ubuntu).
>
> (gdb) backtrace
> #0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
> #1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
> #2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
> #3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
> #4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
> #5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
> #6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
hum, I recall discussing the same issue,
I thought it was already fixed :-\ in any case:
Acked-by: Jiri Olsa <[email protected]>
thanks,
jirka
>
> The root cause is, evlist__add_bpf_sb_event() just returns 0 if
> HAVE_LIBBPF_SUPPORT is not defined (inline function path). So it will
> not create a valid evsel for side-band event.
>
> But perf-record still creates BPF side band thread to process the
> side-band event, then the error happpens.
>
> We can reproduce this issue by removing the libelf-dev. e.g.
> 1. apt-get remove libelf-dev
> 2. perf record -a -- sleep 1
>
> root@test:~# ./perf record -a -- sleep 1
> perf: Segmentation fault
> Obtained 6 stack frames.
> ./perf(+0x28eee8) [0x5562d6ef6ee8]
> /lib/x86_64-linux-gnu/libc.so.6(+0x46210) [0x7fbfdc65f210]
> ./perf(+0x342e74) [0x5562d6faae74]
> ./perf(+0x257e39) [0x5562d6ebfe39]
> /lib/x86_64-linux-gnu/libpthread.so.0(+0x9609) [0x7fbfdc990609]
> /lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7fbfdc73b103]
> Segmentation fault (core dumped)
>
> To fix this issue,
>
> 1. We either install the missing libraries to let HAVE_LIBBPF_SUPPORT
> be defined.
> e.g. apt-get install libelf-dev and install other related libraries.
>
> 2. Use this patch to skip the side-band event setup if HAVE_LIBBPF_SUPPORT
> is not set.
>
> Signed-off-by: Jin Yao <[email protected]>
> ---
> tools/perf/builtin-record.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index b6bdccd875bc..ae97f98e2753 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -1506,6 +1506,7 @@ static int record__synthesize(struct record *rec, bool tail)
> return err;
> }
>
> +#ifdef HAVE_LIBBPF_SUPPORT
> static int record__process_signal_event(union perf_event *event __maybe_unused, void *data)
> {
> struct record *rec = data;
> @@ -1550,6 +1551,12 @@ static int record__setup_sb_evlist(struct record *rec)
>
> return 0;
> }
> +#else
> +static int record__setup_sb_evlist(struct record *rec __maybe_unused)
> +{
> + return 0;
> +}
> +#endif
>
> static int __cmd_record(struct record *rec, int argc, const char **argv)
> {
> --
> 2.17.1
>
Hi Jiri,
On 8/7/2020 3:43 AM, Jiri Olsa wrote:
> On Wed, Aug 05, 2020 at 10:29:37AM +0800, Jin Yao wrote:
>> We received an error report that perf-record caused 'Segmentation fault'
>> on a newly system (e.g. on the new installed ubuntu).
>>
>> (gdb) backtrace
>> #0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
>> #1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
>> #2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
>> #3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
>> #4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
>> #5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
>> #6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
>
> hum, I recall discussing the same issue,
> I thought it was already fixed :-\ in any case:
>
Is it possible some patches have been posted but we missed? :)
> Acked-by: Jiri Olsa <[email protected]>
>
Thanks!
Thanks
Jin Yao
> thanks,
> jirka
>
>>
>> The root cause is, evlist__add_bpf_sb_event() just returns 0 if
>> HAVE_LIBBPF_SUPPORT is not defined (inline function path). So it will
>> not create a valid evsel for side-band event.
>>
>> But perf-record still creates BPF side band thread to process the
>> side-band event, then the error happpens.
>>
>> We can reproduce this issue by removing the libelf-dev. e.g.
>> 1. apt-get remove libelf-dev
>> 2. perf record -a -- sleep 1
>>
>> root@test:~# ./perf record -a -- sleep 1
>> perf: Segmentation fault
>> Obtained 6 stack frames.
>> ./perf(+0x28eee8) [0x5562d6ef6ee8]
>> /lib/x86_64-linux-gnu/libc.so.6(+0x46210) [0x7fbfdc65f210]
>> ./perf(+0x342e74) [0x5562d6faae74]
>> ./perf(+0x257e39) [0x5562d6ebfe39]
>> /lib/x86_64-linux-gnu/libpthread.so.0(+0x9609) [0x7fbfdc990609]
>> /lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7fbfdc73b103]
>> Segmentation fault (core dumped)
>>
>> To fix this issue,
>>
>> 1. We either install the missing libraries to let HAVE_LIBBPF_SUPPORT
>> be defined.
>> e.g. apt-get install libelf-dev and install other related libraries.
>>
>> 2. Use this patch to skip the side-band event setup if HAVE_LIBBPF_SUPPORT
>> is not set.
>>
>> Signed-off-by: Jin Yao <[email protected]>
>> ---
>> tools/perf/builtin-record.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index b6bdccd875bc..ae97f98e2753 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -1506,6 +1506,7 @@ static int record__synthesize(struct record *rec, bool tail)
>> return err;
>> }
>>
>> +#ifdef HAVE_LIBBPF_SUPPORT
>> static int record__process_signal_event(union perf_event *event __maybe_unused, void *data)
>> {
>> struct record *rec = data;
>> @@ -1550,6 +1551,12 @@ static int record__setup_sb_evlist(struct record *rec)
>>
>> return 0;
>> }
>> +#else
>> +static int record__setup_sb_evlist(struct record *rec __maybe_unused)
>> +{
>> + return 0;
>> +}
>> +#endif
>>
>> static int __cmd_record(struct record *rec, int argc, const char **argv)
>> {
>> --
>> 2.17.1
>>
>
Em Thu, Aug 06, 2020 at 09:43:57PM +0200, Jiri Olsa escreveu:
> On Wed, Aug 05, 2020 at 10:29:37AM +0800, Jin Yao wrote:
> > We received an error report that perf-record caused 'Segmentation fault'
> > on a newly system (e.g. on the new installed ubuntu).
> >
> > (gdb) backtrace
> > #0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
> > #1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
> > #2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
> > #3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
> > #4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
> > #5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
> > #6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
>
> hum, I recall discussing the same issue,
> I thought it was already fixed :-\ in any case:
>
> Acked-by: Jiri Olsa <[email protected]>
I added this:
Fixes: 23cbb41c939a ("perf record: Move side band evlist setup to separate routine")
To help this fixe go back to a few stable kernels. Technically the
problem was introduced much earlier, when the side band thread was
added, but then this would require more cherry-picking of patches and
since we have a workaround, i.e. build with libbpf, I think this is
enough.
Applied,
- Arnaldo
> thanks,
> jirka
>
> >
> > The root cause is, evlist__add_bpf_sb_event() just returns 0 if
> > HAVE_LIBBPF_SUPPORT is not defined (inline function path). So it will
> > not create a valid evsel for side-band event.
> >
> > But perf-record still creates BPF side band thread to process the
> > side-band event, then the error happpens.
> >
> > We can reproduce this issue by removing the libelf-dev. e.g.
> > 1. apt-get remove libelf-dev
> > 2. perf record -a -- sleep 1
> >
> > root@test:~# ./perf record -a -- sleep 1
> > perf: Segmentation fault
> > Obtained 6 stack frames.
> > ./perf(+0x28eee8) [0x5562d6ef6ee8]
> > /lib/x86_64-linux-gnu/libc.so.6(+0x46210) [0x7fbfdc65f210]
> > ./perf(+0x342e74) [0x5562d6faae74]
> > ./perf(+0x257e39) [0x5562d6ebfe39]
> > /lib/x86_64-linux-gnu/libpthread.so.0(+0x9609) [0x7fbfdc990609]
> > /lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7fbfdc73b103]
> > Segmentation fault (core dumped)
> >
> > To fix this issue,
> >
> > 1. We either install the missing libraries to let HAVE_LIBBPF_SUPPORT
> > be defined.
> > e.g. apt-get install libelf-dev and install other related libraries.
> >
> > 2. Use this patch to skip the side-band event setup if HAVE_LIBBPF_SUPPORT
> > is not set.
> >
> > Signed-off-by: Jin Yao <[email protected]>
> > ---
> > tools/perf/builtin-record.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > index b6bdccd875bc..ae97f98e2753 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -1506,6 +1506,7 @@ static int record__synthesize(struct record *rec, bool tail)
> > return err;
> > }
> >
> > +#ifdef HAVE_LIBBPF_SUPPORT
> > static int record__process_signal_event(union perf_event *event __maybe_unused, void *data)
> > {
> > struct record *rec = data;
> > @@ -1550,6 +1551,12 @@ static int record__setup_sb_evlist(struct record *rec)
> >
> > return 0;
> > }
> > +#else
> > +static int record__setup_sb_evlist(struct record *rec __maybe_unused)
> > +{
> > + return 0;
> > +}
> > +#endif
> >
> > static int __cmd_record(struct record *rec, int argc, const char **argv)
> > {
> > --
> > 2.17.1
> >
>
--
- Arnaldo
Em Fri, Aug 07, 2020 at 09:08:24AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Aug 06, 2020 at 09:43:57PM +0200, Jiri Olsa escreveu:
> > On Wed, Aug 05, 2020 at 10:29:37AM +0800, Jin Yao wrote:
> > > We received an error report that perf-record caused 'Segmentation fault'
> > > on a newly system (e.g. on the new installed ubuntu).
> > >
> > > (gdb) backtrace
> > > #0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
> > > #1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
> > > #2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
> > > #3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
> > > #4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
> > > #5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
> > > #6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
> >
> > hum, I recall discussing the same issue,
> > I thought it was already fixed :-\ in any case:
> >
> > Acked-by: Jiri Olsa <[email protected]>
>
> I added this:
>
> Fixes: 23cbb41c939a ("perf record: Move side band evlist setup to separate routine")
>
> To help this fixe go back to a few stable kernels. Technically the
> problem was introduced much earlier, when the side band thread was
> added, but then this would require more cherry-picking of patches and
> since we have a workaround, i.e. build with libbpf, I think this is
> enough.
I backtrack on that, as the sideband event is not just for BPF... The
switch-output-event code uses it as well, so it can't be dependent on
LIBBPF being built...
I'll see what I can do
- Arnaldo
Em Fri, Aug 07, 2020 at 09:09:56AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Aug 07, 2020 at 09:08:24AM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Thu, Aug 06, 2020 at 09:43:57PM +0200, Jiri Olsa escreveu:
> > > On Wed, Aug 05, 2020 at 10:29:37AM +0800, Jin Yao wrote:
> > > > We received an error report that perf-record caused 'Segmentation fault'
> > > > on a newly system (e.g. on the new installed ubuntu).
> > > >
> > > > (gdb) backtrace
> > > > #0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
> > > > #1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
> > > > #2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
> > > > #3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
> > > > #4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
> > > > #5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
> > > > #6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
> > >
> > > hum, I recall discussing the same issue,
> > > I thought it was already fixed :-\ in any case:
> > >
> > > Acked-by: Jiri Olsa <[email protected]>
> >
> > I added this:
> >
> > Fixes: 23cbb41c939a ("perf record: Move side band evlist setup to separate routine")
> >
> > To help this fixe go back to a few stable kernels. Technically the
> > problem was introduced much earlier, when the side band thread was
> > added, but then this would require more cherry-picking of patches and
> > since we have a workaround, i.e. build with libbpf, I think this is
> > enough.
>
> I backtrack on that, as the sideband event is not just for BPF... The
> switch-output-event code uses it as well, so it can't be dependent on
> LIBBPF being built...
>
> I'll see what I can do
So this is the change I made, the side band thread is may have been
already created by
[acme@quaco ~]$ perf record -h switch-output-event
Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]
--switch-output-event <switch output event>
switch output event selector. use 'perf list' to list available events
[acme@quaco ~]$
I'm doing some extra checking now on your report, and the patch below
has skews because it clashed with the clockid patches by Jiri so I had
to resolve its merge.
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 7d97c8e9f7f9..c12b5b072519 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1511,6 +1511,7 @@ static int record__synthesize(struct record *rec, bool tail)
return err;
}
+#ifdef HAVE_LIBBPF_SUPPORT
static int record__process_signal_event(union perf_event *event __maybe_unused, void *data)
{
struct record *rec = data;
@@ -1592,6 +1593,12 @@ static int record__init_clock(struct record *rec)
session->header.env.clock.clockid_ns = ref;
return 0;
}
+#else
+static int record__setup_sb_evlist(struct record *rec __maybe_unused)
+{
+ return 0;
+}
+#endif
static int __cmd_record(struct record *rec, int argc, const char **argv)
{
Em Fri, Aug 07, 2020 at 09:16:29AM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Aug 07, 2020 at 09:09:56AM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Fri, Aug 07, 2020 at 09:08:24AM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Thu, Aug 06, 2020 at 09:43:57PM +0200, Jiri Olsa escreveu:
> > > > On Wed, Aug 05, 2020 at 10:29:37AM +0800, Jin Yao wrote:
> > > > > We received an error report that perf-record caused 'Segmentation fault'
> > > > > on a newly system (e.g. on the new installed ubuntu).
> > > > >
> > > > > (gdb) backtrace
> > > > > #0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
> > > > > #1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
> > > > > #2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
> > > > > #3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
> > > > > #4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
> > > > > #5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
> > > > > #6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
> > > >
> > > > hum, I recall discussing the same issue,
> > > > I thought it was already fixed :-\ in any case:
> > > >
> > > > Acked-by: Jiri Olsa <[email protected]>
> > >
> > > I added this:
> > >
> > > Fixes: 23cbb41c939a ("perf record: Move side band evlist setup to separate routine")
> > >
> > > To help this fixe go back to a few stable kernels. Technically the
> > > problem was introduced much earlier, when the side band thread was
> > > added, but then this would require more cherry-picking of patches and
> > > since we have a workaround, i.e. build with libbpf, I think this is
> > > enough.
> >
> > I backtrack on that, as the sideband event is not just for BPF... The
> > switch-output-event code uses it as well, so it can't be dependent on
> > LIBBPF being built...
> >
> > I'll see what I can do
>
> So this is the change I made, the side band thread is may have been
> already created by
>
> [acme@quaco ~]$ perf record -h switch-output-event
>
> Usage: perf record [<options>] [<command>]
> or: perf record [<options>] -- <command> [<options>]
>
> --switch-output-event <switch output event>
> switch output event selector. use 'perf list' to list available events
>
> [acme@quaco ~]$
>
> I'm doing some extra checking now on your report, and the patch below
> has skews because it clashed with the clockid patches by Jiri so I had
> to resolve its merge.
Sorry, I resent your patch, doh, here is the end result, with my change,
its ok to call perf_evlist__start_sb_thread() with a NULL evlist, it'll
just return 0.
- Arnald
commit b13536a7e93680625094beb18cdce4ae47a3dbfb
Author: Jin Yao <[email protected]>
Date: Wed Aug 5 10:29:37 2020 +0800
perf record: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set
We received an error report that perf-record caused 'Segmentation fault'
on a newly system (e.g. on the new installed ubuntu).
(gdb) backtrace
#0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
#1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
#2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
#3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
#4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
#5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
The root cause is, evlist__add_bpf_sb_event() just returns 0 if
HAVE_LIBBPF_SUPPORT is not defined (inline function path). So it will
not create a valid evsel for side-band event.
But perf-record still creates BPF side band thread to process the
side-band event, then the error happpens.
We can reproduce this issue by removing the libelf-dev. e.g.
1. apt-get remove libelf-dev
2. perf record -a -- sleep 1
root@test:~# ./perf record -a -- sleep 1
perf: Segmentation fault
Obtained 6 stack frames.
./perf(+0x28eee8) [0x5562d6ef6ee8]
/lib/x86_64-linux-gnu/libc.so.6(+0x46210) [0x7fbfdc65f210]
./perf(+0x342e74) [0x5562d6faae74]
./perf(+0x257e39) [0x5562d6ebfe39]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x9609) [0x7fbfdc990609]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7fbfdc73b103]
Segmentation fault (core dumped)
To fix this issue,
1. We either install the missing libraries to let HAVE_LIBBPF_SUPPORT
be defined.
e.g. apt-get install libelf-dev and install other related libraries.
2. Use this patch to skip the side-band event setup if HAVE_LIBBPF_SUPPORT
is not set.
Committer notes:
The side band thread is not used just with BPF, it is also used with
--switch-output-event, so narrow the ifdef to the BPF specific part.
Fixes: 23cbb41c939a ("perf record: Move side band evlist setup to separate routine")
Signed-off-by: Jin Yao <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Jin Yao <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 7d97c8e9f7f9..f91352f847c0 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1531,7 +1531,7 @@ static int record__setup_sb_evlist(struct record *rec)
evlist__set_cb(rec->sb_evlist, record__process_signal_event, rec);
rec->thread_id = pthread_self();
}
-
+#ifdef HAVE_LIBBPF_SUPPORT
if (!opts->no_bpf_event) {
if (rec->sb_evlist == NULL) {
rec->sb_evlist = evlist__new();
@@ -1547,7 +1547,7 @@ static int record__setup_sb_evlist(struct record *rec)
return -1;
}
}
-
+#endif
if (perf_evlist__start_sb_thread(rec->sb_evlist, &rec->opts.target)) {
pr_debug("Couldn't start the BPF side band thread:\nBPF programs starting from now on won't be annotatable\n");
opts->no_bpf_event = true;
Hi Arnaldo,
On 8/7/2020 8:28 PM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Aug 07, 2020 at 09:16:29AM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Fri, Aug 07, 2020 at 09:09:56AM -0300, Arnaldo Carvalho de Melo escreveu:
>>> Em Fri, Aug 07, 2020 at 09:08:24AM -0300, Arnaldo Carvalho de Melo escreveu:
>>>> Em Thu, Aug 06, 2020 at 09:43:57PM +0200, Jiri Olsa escreveu:
>>>>> On Wed, Aug 05, 2020 at 10:29:37AM +0800, Jin Yao wrote:
>>>>>> We received an error report that perf-record caused 'Segmentation fault'
>>>>>> on a newly system (e.g. on the new installed ubuntu).
>>>>>>
>>>>>> (gdb) backtrace
>>>>>> #0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
>>>>>> #1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
>>>>>> #2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
>>>>>> #3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
>>>>>> #4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
>>>>>> #5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
>>>>>> #6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
>>>>>
>>>>> hum, I recall discussing the same issue,
>>>>> I thought it was already fixed :-\ in any case:
>>>>>
>>>>> Acked-by: Jiri Olsa <[email protected]>
>>>>
>>>> I added this:
>>>>
>>>> Fixes: 23cbb41c939a ("perf record: Move side band evlist setup to separate routine")
>>>>
>>>> To help this fixe go back to a few stable kernels. Technically the
>>>> problem was introduced much earlier, when the side band thread was
>>>> added, but then this would require more cherry-picking of patches and
>>>> since we have a workaround, i.e. build with libbpf, I think this is
>>>> enough.
>>>
>>> I backtrack on that, as the sideband event is not just for BPF... The
>>> switch-output-event code uses it as well, so it can't be dependent on
>>> LIBBPF being built...
>>>
>>> I'll see what I can do
>>
>> So this is the change I made, the side band thread is may have been
>> already created by
>>
>> [acme@quaco ~]$ perf record -h switch-output-event
>>
>> Usage: perf record [<options>] [<command>]
>> or: perf record [<options>] -- <command> [<options>]
>>
>> --switch-output-event <switch output event>
>> switch output event selector. use 'perf list' to list available events
>>
>> [acme@quaco ~]$
>>
>> I'm doing some extra checking now on your report, and the patch below
>> has skews because it clashed with the clockid patches by Jiri so I had
>> to resolve its merge.
>
> Sorry, I resent your patch, doh, here is the end result, with my change,
> its ok to call perf_evlist__start_sb_thread() with a NULL evlist, it'll
> just return 0.
>
> - Arnald
>
>
> commit b13536a7e93680625094beb18cdce4ae47a3dbfb
> Author: Jin Yao <[email protected]>
> Date: Wed Aug 5 10:29:37 2020 +0800
>
> perf record: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set
>
> We received an error report that perf-record caused 'Segmentation fault'
> on a newly system (e.g. on the new installed ubuntu).
>
> (gdb) backtrace
> #0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
> #1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
> #2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
> #3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
> #4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
> #5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
> #6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
>
> The root cause is, evlist__add_bpf_sb_event() just returns 0 if
> HAVE_LIBBPF_SUPPORT is not defined (inline function path). So it will
> not create a valid evsel for side-band event.
>
> But perf-record still creates BPF side band thread to process the
> side-band event, then the error happpens.
>
> We can reproduce this issue by removing the libelf-dev. e.g.
> 1. apt-get remove libelf-dev
> 2. perf record -a -- sleep 1
>
> root@test:~# ./perf record -a -- sleep 1
> perf: Segmentation fault
> Obtained 6 stack frames.
> ./perf(+0x28eee8) [0x5562d6ef6ee8]
> /lib/x86_64-linux-gnu/libc.so.6(+0x46210) [0x7fbfdc65f210]
> ./perf(+0x342e74) [0x5562d6faae74]
> ./perf(+0x257e39) [0x5562d6ebfe39]
> /lib/x86_64-linux-gnu/libpthread.so.0(+0x9609) [0x7fbfdc990609]
> /lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7fbfdc73b103]
> Segmentation fault (core dumped)
>
> To fix this issue,
>
> 1. We either install the missing libraries to let HAVE_LIBBPF_SUPPORT
> be defined.
> e.g. apt-get install libelf-dev and install other related libraries.
>
> 2. Use this patch to skip the side-band event setup if HAVE_LIBBPF_SUPPORT
> is not set.
>
> Committer notes:
>
> The side band thread is not used just with BPF, it is also used with
> --switch-output-event, so narrow the ifdef to the BPF specific part.
>
> Fixes: 23cbb41c939a ("perf record: Move side band evlist setup to separate routine")
> Signed-off-by: Jin Yao <[email protected]>
> Acked-by: Jiri Olsa <[email protected]>
> Cc: Alexander Shishkin <[email protected]>
> Cc: Andi Kleen <[email protected]>
> Cc: Jin Yao <[email protected]>
> Cc: Kan Liang <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Link: http://lore.kernel.org/lkml/[email protected]
> Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 7d97c8e9f7f9..f91352f847c0 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -1531,7 +1531,7 @@ static int record__setup_sb_evlist(struct record *rec)
> evlist__set_cb(rec->sb_evlist, record__process_signal_event, rec);
> rec->thread_id = pthread_self();
> }
> -
> +#ifdef HAVE_LIBBPF_SUPPORT
> if (!opts->no_bpf_event) {
> if (rec->sb_evlist == NULL) {
> rec->sb_evlist = evlist__new();
> @@ -1547,7 +1547,7 @@ static int record__setup_sb_evlist(struct record *rec)
> return -1;
> }
> }
> -
> +#endif
> if (perf_evlist__start_sb_thread(rec->sb_evlist, &rec->opts.target)) {
> pr_debug("Couldn't start the BPF side band thread:\nBPF programs starting from now on won't be annotatable\n");
> opts->no_bpf_event = true;
>
Thanks so much for helping to refine the patch!
Thanks
Jin Yao