valgrind-users — General discussion list for Valgrind users

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Philippe W. <phi...@sk...>]

On Wed, 2022-08-31 at 17:42 +0000, Bresalier, Rob (Nokia - US/Murray Hill) wrote:
> > When running memcheck on a massive monolith embedded executable
> > (237MB stripped, 1.8GiB unstripped), after I stop the executable under
> > valgrind I see the "HEAP SUMMARY" but then valgrind dies before any leak
> > reports are printed. The parent process sees that the return status of
> > memcheck is that it was SIGKILLed (status returned in waitpid call is '9').
> 
> We found that removing a call to _exit(0) made it so that valgrind is no longer
> SIGKILLED.
> 
> Any ideas why using _exit(0) may get rid of valgrind getting SIGKILLed?
> 
> Previously exit(0) was called, without the leading underscore, but changed it to
> _exit(0) to really make sure no memory was being deallocated. This worked well on a
> different process, so we carried it over to this one, that is why we did it.
> 
> Even with exit(0) (no underscore), in this process there is not much deallocation going
> on in exit handlers, so have lots of doubts that valgrind/memcheck was using too much
> memory and invoking the OOM killer.
> 
> Using strace and dmesg while we had _exit(0) in use didn't show that OOM killer was
> SIGKILLing valgrind.
> 
> I also tried reducing number of callers from 12 to 6 when using _exit(0), still got the
> SIGKILL.
> 
> Also tried using a system that had an additional 4GByte of memory, and also got the
> SIGKILL there.
> 
> So I have many doubts that Valgrind was getting SIGKILLed due to too much memory usage.
> 
> Don't know why removing _exit(0) got rid of the SIGKILL. Was wondering if anyone had any
> ideas?
Normally, if it is the OOM that kills a process, you should find a trace of this in the
system logs.

I do not understand what you mean by reducing the nr of callers from 12 to 6.
What are these callers ? Is that some threads of the process you are
running under valgrind ?

And just in case: are you using the last version of Valgrind ?

You might use "strace" on valgrind to see what is going on at the time _exit(0) is called.
You might also start valgrind with some debug trace e.g.  -d -d -d -d -v -v -v -v

Philippe

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Bresalier, R. (N. - US/M. Hill) <rob...@no...>]

> When running memcheck on a massive monolith embedded executable
> (237MB stripped, 1.8GiB unstripped), after I stop the executable under
> valgrind I see the "HEAP SUMMARY" but then valgrind dies before any leak
> reports are printed. The parent process sees that the return status of
> memcheck is that it was SIGKILLed (status returned in waitpid call is '9').

We found that removing a call to _exit(0) made it so that valgrind is no longer SIGKILLED.

Any ideas why using _exit(0) may get rid of valgrind getting SIGKILLed?

Previously exit(0) was called, without the leading underscore, but changed it to _exit(0) to really make sure no memory was being deallocated. This worked well on a different process, so we carried it over to this one, that is why we did it.

Even with exit(0) (no underscore), in this process there is not much deallocation going on in exit handlers, so have lots of doubts that valgrind/memcheck was using too much memory and invoking the OOM killer.

Using strace and dmesg while we had _exit(0) in use didn't show that OOM killer was SIGKILLing valgrind.

I also tried reducing number of callers from 12 to 6 when using _exit(0), still got the SIGKILL.

Also tried using a system that had an additional 4GByte of memory, and also got the SIGKILL there.

So I have many doubts that Valgrind was getting SIGKILLed due to too much memory usage.

Don't know why removing _exit(0) got rid of the SIGKILL. Was wondering if anyone had any ideas?

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Philippe W. <phi...@sk...>]

> 
> > Is there anything that can be done with memcheck to make it consume less memory?
> 
> No.
In fact, Yes :).
Or more precisely, yes, memory can be somewhat reduced :).
See my other mail.

Philippe

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Philippe W. <phi...@sk...>]

On Fri, 2022-08-05 at 15:34 +0000, Bresalier, Rob (Nokia - US/Murray Hill) wrote:
> > If finding memory leaks is the only goal (for instance, if you are satisfied that
> > memcheck has found all the overrun blocks, uninitialized reads, etc.) then
> > https://github.com/KDE/heaptrack  is the best tool.  
> 
> Thanks! I didn't know about heaptrack. I will look definitely into that. Does heaptrack
> also show  the 'still reachable' types of leaks that memcheck does?
> 
> Any chance that the 'massif' tool would survive the OOM killer? This may be easier for
> me to get going as I already have valgrind built.
> 
> Is there anything that can be done with memcheck to make it consume less memory?
You might be interested in looking at the slides of the FOSDEM presentation
  'Tuning Valgrind for your workload'
https://archive.fosdem.org/2015/schedule/event/valgrind_tuning/attachments/slides/743/export/events/attachments/valgrind_tuning/slides/743/tuning_V_for_your_workload.pdf

There are several things you can do to reduce memcheck memory usage.

Note also that you can also run leak search while your program runs,
either via memcheck client requests or from the shell, using vgdb.

Philippe

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Julian S. <jse...@gm...>]

> Is there anything that can be done with memcheck to make it consume less memory?

First of all, figure out whether memcheck got sigkilled because the machine
ran out of space, or because you hit some shell limit/ulimit.  In the former
case, you can then try adding swap space to the machine.  In the latter case
you'll need to mess with the shell's ulimit settings.

You could also try reducing the (data) size of the workload.

Massif and Memcheck are different tools and do largely different things.
Whether or not you can use one or the other depends a lot on the specifics
of what problem you're trying to solve.

J

Re: [Valgrind-users] Valgrind trace Memory Addresses while running?

[Eliot M. <mo...@cs...>]

On 8/5/2022 8:47 PM, G N Srinivasa Prasanna wrote:
> Thanks for this information.
> 
> We are doing a memory system simulation, and need the address stream. At this point of time, we 
> don't care if we need a Terabyte even, we can delete the files later.
> 
> Is there anything we can use from Valgrind?

The lackey tool does just that - output a trace of memory references.

-- Eliot Moss

Re: [Valgrind-users] Valgrind trace Memory Addresses while running?

[G N S. P. <gns...@ii...>]

Thanks, will check it out.

Best
________________________________
From: Eliot Moss <mo...@cs...>
Sent: 06 August 2022 07:10
To: G N Srinivasa Prasanna <gns...@ii...>; John Reiser <jr...@bi...>; val...@li... <val...@li...>
Subject: Re: [Valgrind-users] Valgrind trace Memory Addresses while running?

On 8/5/2022 8:47 PM, G N Srinivasa Prasanna wrote:
> Thanks for this information.
>
> We are doing a memory system simulation, and need the address stream. At this point of time, we
> don't care if we need a Terabyte even, we can delete the files later.
>
> Is there anything we can use from Valgrind?

The lackey tool does just that - output a trace of memory references.

-- Eliot Moss

Re: [Valgrind-users] Valgrind trace Memory Addresses while running?

[G N S. P. <gns...@ii...>]

Thanks for this information.

We are doing a memory system simulation, and need the address stream. At this point of time, we don't care if we need a Terabyte even, we can delete the files later.

Is there anything we can use from Valgrind?

Best
________________________________
From: John Reiser <jr...@bi...>
Sent: 06 August 2022 01:18
To: val...@li... <val...@li...>
Subject: Re: [Valgrind-users] Valgrind trace Memory Addresses while running?

>> if we can get a list of all the physical addresses the program used, in the order the program accessed them, and whether read/write.


>  For any real world application the size of the log would be overwhelmingly huge ... (unless you only want unique addresses).

Of course this is the purpose of data compression (such as gzip, etc).
You get some/much/most of the benefit of restricting to unique addresses
while still capturing the entire stream of references.

But as Paul noted, valgrind works in virtual addresses.
Getting all the actual physical addresses is close to impossible.
If you are working in an embedded device environment
and care only about a small handful of memory-mapped
device registers, then you can (must) process the
mapping yourself.





_______________________________________________
Valgrind-users mailing list
Val...@li...
https://lists.sourceforge.net/lists/listinfo/valgrind-users

[Valgrind-users] massif doesn't detect 'definite' leaks?

[Bresalier, R. (N. - US/M. Hill) <rob...@no...>]

I tried 'massif' on a simple program shown below where there are "definitely lost" leaks.

massif doesn't seem to find "definitely lost" leaks, is this correct?

I'm tried with both 3.19.0 and 3.15.0 versions of valgrind/massif, same result, "definitely lost" leaks are not found.

I launch massif via:

valgrind --tool=massif --sigill-diagnostics=no --error-limit=no --massif-out-file=definitely.%p.massif definitely.elf

When I use memcheck it does find these definite leaks as below:

==29917== 60 bytes in 3 blocks are definitely lost in loss record 1 of 1
==29917==    at 0x402F67C: malloc (vg_replace_malloc.c:381)
==29917==    by 0x80491D1: f2() (definitely.cpp:11)
==29917==    by 0x804920F: f1() (definitely.cpp:17)
==29917==    by 0x8049262: main (definitely.cpp:25)

But massif doesn't find them at all? Is this correct?

When I use massif on a program with "still reachable" it does find the still reachable, but it isn't finding definite leaks.

Shouldn't massif also find definite leaks?

The C code for "definitely.elf" is below:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

void*
f2()
{
  return malloc(20);
}

void
f1()
{
  f2();
}

int
main()
{
  for (int i = 1; i <= 3; i++)
  {
    f1();
  }

  return 0;
}

Thanks,
Rob

Re: [Valgrind-users] Valgrind trace Memory Addresses while running?

[John R. <jr...@bi...>]

>> if we can get a list of all the physical addresses the program used, in the order the program accessed them, and whether read/write.


>  For any real world application the size of the log would be overwhelmingly huge ... (unless you only want unique addresses).

Of course this is the purpose of data compression (such as gzip, etc).
You get some/much/most of the benefit of restricting to unique addresses
while still capturing the entire stream of references.

But as Paul noted, valgrind works in virtual addresses.
Getting all the actual physical addresses is close to impossible.
If you are working in an embedded device environment
and care only about a small handful of memory-mapped
device registers, then you can (must) process the
mapping yourself.

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[John R. <jr...@bi...>]

>> Is there anything that can be done with memcheck to make it consume less memory?
> 
> No.

Well, you can use the command-line argument "--num-callers=<number>" to reduce the length
of tracebacks that are stored in the "red zones" just before and after an allocated block.
This might help enough if you have zillions of "still reachable" blocks.  But you get
shorter tracebacks, which might not give enough information to find and fix the leak
quickly.
If you do not have zillions of "still reachable" blocks, then --num-callers
will not help so much; but probably would not be needed anyway.

Re: [Valgrind-users] Valgrind trace Memory Addresses while running?

[Paul F. <pj...@wa...>]

> On 5 Aug 2022, at 20:53, G N Srinivasa Prasanna <gns...@ii...> wrote:
> 
> 
> This is the first time we are using Valgrind, and we want to know if we can get a list of all the physical addresses the program used, in the order the program accessed them, and whether read/write.
> 
> Please let us know if we can get this from Valgrind - the webpage information is not clear.
> 

Hi

Why do you need this?

I’m not sure how to translate from virtual to physical address. Do you really mean physical address? For any real world application the size of the log would be overwhelmingly huge and I suspect would very rapidly fill most disks (unless you only want unique addresses).

A+
Paul

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[John R. <jr...@bi...>]

> Does heaptrack also show  the 'still reachable' types of leaks that memcheck does?

Heaptrack intercepts malloc+free+etc, then logs the parameters, result, and
traceback; but otherwise lets the progcess-original malloc+free+etc do the work.
Heaptrack does not notice, and does not care, what you do with the result of
malloc(), except whether or not the pointer returned by malloc() ever gets
passed as an argument to free().

When heaptrack performs analysis, then any result from malloc() that has not
been free()d is a "leak" as far as heaptrack is concerned.  So that includes
what memcheck calls "still reachable" but not (yet) a leak.

> Any chance that the 'massif' tool would survive the OOM killer? This may be easier for me to get going as I already have valgrind built.

Worth a try if you have a day or so to spend.  Like all valgrind tools,
massif relies on emulating the instruction stream, so the basic ~10X
run-time slowdown applies.

> Is there anything that can be done with memcheck to make it consume less memory?

No.

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Bresalier, R. (N. - US/M. Hill) <rob...@no...>]

> > If you want to know for sure who killed it then strace it while it
> > runs and it should show you who sends the signel but my bet is that
> > it's the kernel.
> 

I tried strace -p <pid> on my process before I triggered its exit. The strace output ends saying with: "+++ killed by SIGKILL +++", but I don't find anything about who sent it.

> Or possibly watch `dmesg -w` running in another shell.
> 

I tried 'dmesg -w' but it didn't say anything about the SIGKILL. Is there something that has to be configured for dmesg to say the source of the SIGKILL?

[Valgrind-users] Valgrind trace Memory Addresses while running?

[G N S. P. <gns...@ii...>]

This is the first time we are using Valgrind, and we want to know if we can get a list of all the physical addresses the program used, in the order the program accessed them, and whether read/write.

Please let us know if we can get this from Valgrind - the webpage information is not clear.

Thanks
Prasanna

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Bresalier, R. (N. - US/M. Hill) <rob...@no...>]

Thanks Tom.

Do you think I'd have better luck using the "massif" tool? Would "massif" be able to avoid the OOM killer?

Or is there a way to reduce the amount of memory that memcheck will use?

-----Original Message-----
From: Tom Hughes <to...@co...> 
Sent: Friday, August 5, 2022 10:08 AM
To: Bresalier, Rob (Nokia - US/Murray Hill) <rob...@no...>; val...@li...
Subject: Re: memcheck is getting SIGKILLed before leak report is output

On 05/08/2022 14:09, Bresalier, Rob (Nokia - US/Murray Hill) wrote:

> When running memcheck on a massive monolith embedded executable (237MB 
> stripped, 1.8GiB unstripped), after I stop the executable under 
> valgrind I see the “HEAP SUMMARY” but then valgrind dies before any 
> leak reports are printed. The parent process sees that the return 
> status of memcheck is that it was SIGKILLed (status returned in 
> waitpid call is ‘9’). I am 99.9% sure that the parent process is not the one sending the SIGKILL.
> Is it possible that valgrind SIGKILLs itself? Is there a reason that 
> the linux kernel (Wind River Linux) could be sending a SIGKILL to 
> valgrind/memcheck? I do not see any messages about Out of Memory/OOM 
> killer killing valgrind. Previous experience with this executable is 
> that there are almost 3 million leak reports (most of them are “still 
> reachable”), could that be occupying too much memory. Any ideas/advice 
> to figure out what is going on?

Almost certainly the kernel OOM kiied it.

If you want to know for sure who killed it then strace it while it runs and it should show you who sends the signel but my bet is that it's the kernel.

> One thing I see in the logs is about “unhandled ioctl 0xa5 with no 
> size/direction hints”. Could this be a trigger for this crash/sigkill?

Not really, no.

Tom

--
Tom Hughes (to...@co...)
http://compton.nu/

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Bresalier, R. (N. - US/M. Hill) <rob...@no...>]

> If finding memory leaks is the only goal (for instance, if you are satisfied that
> memcheck has found all the overrun blocks, uninitialized reads, etc.) then
> https://github.com/KDE/heaptrack  is the best tool.  

Thanks! I didn't know about heaptrack. I will look definitely into that. Does heaptrack also show  the 'still reachable' types of leaks that memcheck does?

Any chance that the 'massif' tool would survive the OOM killer? This may be easier for me to get going as I already have valgrind built.

Is there anything that can be done with memcheck to make it consume less memory?

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Julian S. <jse...@gm...>]

On 05/08/2022 16:08, Tom Hughes via Valgrind-users wrote:

> If you want to know for sure who killed it then strace it while
> it runs and it should show you who sends the signel but my bet is
> that it's the kernel.

Or possibly watch `dmesg -w` running in another shell.

J

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[John R. <jr...@bi...>]

> When running memcheck on a massive monolith embedded executable (237MB stripped, 1.8GiB unstripped), after I stop the executable under valgrind I see the “HEAP SUMMARY” but then valgrind dies before any leak reports are printed.
If finding memory leaks is the only goal (for instance, if you are satisfied
that memcheck has found all the overrun blocks, uninitialized reads, etc.)
then https://github.com/KDE/heaptrack  is the best tool.  The data-gathering
phase runs in any Linux process using LD_PRELOAD and libunwind.  The analysis
phase runs a GUI under KDE, and/or generates *useful* text reports: leaks by
individual size, leaks by total size for a given traceback, allocations
(leaked or not) by frequency or total size, etc.  I like the text-only
analysis, which avoids the requirement for KDE.  Heaptrack CPU overhead
tends to be around 20% or less, so it does not take forever.  Heaptrack
does require disk space to record data (sequential access only),
so you may need several gigabytes (locally or via network.)

Re: [Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Tom H. <to...@co...>]

On 05/08/2022 14:09, Bresalier, Rob (Nokia - US/Murray Hill) wrote:

> When running memcheck on a massive monolith embedded executable (237MB 
> stripped, 1.8GiB unstripped), after I stop the executable under valgrind 
> I see the “HEAP SUMMARY” but then valgrind dies before any leak reports 
> are printed. The parent process sees that the return status of memcheck 
> is that it was SIGKILLed (status returned in waitpid call is ‘9’). I am 
> 99.9% sure that the parent process is not the one sending the SIGKILL. 
> Is it possible that valgrind SIGKILLs itself? Is there a reason that the 
> linux kernel (Wind River Linux) could be sending a SIGKILL to 
> valgrind/memcheck? I do not see any messages about Out of Memory/OOM 
> killer killing valgrind. Previous experience with this executable is 
> that there are almost 3 million leak reports (most of them are “still 
> reachable”), could that be occupying too much memory. Any ideas/advice 
> to figure out what is going on?

Almost certainly the kernel OOM kiied it.

If you want to know for sure who killed it then strace it while
it runs and it should show you who sends the signel but my bet is
that it's the kernel.

> One thing I see in the logs is about “unhandled ioctl 0xa5 with no 
> size/direction hints”. Could this be a trigger for this crash/sigkill?

Not really, no.

Tom

-- 
Tom Hughes (to...@co...)
http://compton.nu/

[Valgrind-users] memcheck is getting SIGKILLed before leak report is output

[Bresalier, R. (N. - US/M. Hill) <rob...@no...>]

When running memcheck on a massive monolith embedded executable (237MB stripped, 1.8GiB unstripped), after I stop the executable under valgrind I see the "HEAP SUMMARY" but then valgrind dies before any leak reports are printed. The parent process sees that the return status of memcheck is that it was SIGKILLed (status returned in waitpid call is '9'). I am 99.9% sure that the parent process is not the one sending the SIGKILL. Is it possible that valgrind SIGKILLs itself? Is there a reason that the linux kernel (Wind River Linux) could be sending a SIGKILL to valgrind/memcheck? I do not see any messages about Out of Memory/OOM killer killing valgrind. Previous experience with this executable is that there are almost 3 million leak reports (most of them are "still reachable"), could that be occupying too much memory. Any ideas/advice to figure out what is going on?

We don't seem to get the sigkill if valgrind/memcheck is stopped earlier in the life of this executable. But to find the leak I need it to run past that point.

I've tried many different versions of valgrind that have worked to find leaks on this executable in the past (3.16.1, 3.18.1, 3.19.0) but they all have this same issue of being sigkilled before any leaks get printed.

One thing I see in the logs is about "unhandled ioctl 0xa5 with no size/direction hints". Could this be a trigger for this crash/sigkill?

Would appreciate any ideas/advice.

Thanks,
Rob

Re: [Valgrind-users] [SGCheck][Array overrun detection] seems found nothing in multiple version

[Paul F. <pj...@wa...>]

Hi

Sgcheck never got beyond experimental and was removed from Valgrind a few versions ago. My advice is simply to not use it.

A+
Paul

> On 4 Aug 2022, at 07:45, Pahome Chen via Valgrind-users <val...@li...> wrote:
> 
> 
> Dear all,
>  
> I read the sgcheck’s doc and know it’s a experimental tool, but it seems found no error even a very simple program.
> Does this still work or need to wait for another version?
>  
> Below is from my script and experiment, and fail in Valgrind-3.8.1/3.9.0/3.10.0/3.11.0/3.12.0
> E.g.
> >$ cat test_valgrind.c
> #include<stdio.h>
> #include<stdlib.h>
> int main()
> {
>     int val[10] = {0};
>     int tmp = val[1], i = 0;
>     tmp += val[15]; // array overrun
>     tmp *= val[20]; // array overrun
>     for (i=0; i<20; ++i) { int tmp = val[i]; } // array overrun
>     return 0;
> }
>  
> When I run above version of Valgrind mentioned, it always comes out following message.
>  
> ==11673== exp-sgcheck, a stack and global array overrun detector
> ==11673== NOTE: This is an Experimental-Class Valgrind Tool
> ==11673== Copyright (C) 2003-2015, and GNU GPL'd, by OpenWorks Ltd et al.
> ==11673== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
> ==11673== Command: ./run
> ==11673==
>  
> exp-sgcheck: sg_main.c:2332 (sg_instrument_IRStmt): the 'impossible' happened.
>  
> host stacktrace:
> ==11673==    at 0x3800CC09: show_sched_status_wrk (m_libcassert.c:343)
> ==11673==    by 0x3800CEF4: report_and_quit (m_libcassert.c:415)
> ==11673==    by 0x3800D127: vgPlain_assert_fail (m_libcassert.c:481)
> ==11673==    by 0x38004A03: sg_instrument_IRStmt (sg_main.c:2332)
> ==11673==    by 0x380003B3: h_instrument (h_main.c:683)
> ==11673==    by 0x3802968D: tool_instrument_then_gdbserver_if_needed (m_translate.c:238)
> ==11673==    by 0x380D3290: LibVEX_Translate (main_main.c:934)
> ==11673==    by 0x380271BF: vgPlain_translate (m_translate.c:1765)
> ==11673==    by 0x3805F857: vgPlain_scheduler (scheduler.c:1048)
> ==11673==    by 0x38090445: run_a_thread_NORETURN (syswrap-linux.c:102)
>  
> sched status:
>   running_tid=1
>  
> Thread 1: status = VgTs_Runnable (lwpid 11673)
> ==11673==    at 0x40169EA: _dl_runtime_resolve_xsave (in /usr/lib64/ld-2.17.so)
> ==11673==    by 0x1B: ???
> ==11673==    by 0x40057F: ??? (in /PATH/peihung/test/run)
> ==11673==    by 0xFFEFFF517: ???
>  
>  
> Note: see also the FAQ in the source distribution.
> It contains workarounds to several common problems.
> In particular, if Valgrind aborted or crashed after
> identifying problems in your program, there's a good chance
> that fixing those problems will prevent Valgrind aborting or
> crashing, especially if it happened in m_mallocfree.c.
>  
> My machine environment is Centos7 and x86_64
>  
>  
>  
>  
> Thanks.
> Best regards,
> Pahome
>  
> _______________________________________________
> Valgrind-users mailing list
> Val...@li...
> https://lists.sourceforge.net/lists/listinfo/valgrind-users

[Valgrind-users] [SGCheck][Array overrun detection] seems found nothing in multiple version

[Pahome C. <Pei...@sy...>]

Dear all,

I read the sgcheck's doc and know it's a experimental tool, but it seems found no error even a very simple program.
Does this still work or need to wait for another version?

Below is from my script and experiment, and fail in Valgrind-3.8.1/3.9.0/3.10.0/3.11.0/3.12.0
E.g.
>$ cat test_valgrind.c
#include<stdio.h>
#include<stdlib.h>
int main()
{
    int val[10] = {0};
    int tmp = val[1], i = 0;
    tmp += val[15]; // array overrun
    tmp *= val[20]; // array overrun
    for (i=0; i<20; ++i) { int tmp = val[i]; } // array overrun
    return 0;
}

When I run above version of Valgrind mentioned, it always comes out following message.

==11673== exp-sgcheck, a stack and global array overrun detector
==11673== NOTE: This is an Experimental-Class Valgrind Tool
==11673== Copyright (C) 2003-2015, and GNU GPL'd, by OpenWorks Ltd et al.
==11673== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==11673== Command: ./run
==11673==

exp-sgcheck: sg_main.c:2332 (sg_instrument_IRStmt): the 'impossible' happened.

host stacktrace:
==11673==    at 0x3800CC09: show_sched_status_wrk (m_libcassert.c:343)
==11673==    by 0x3800CEF4: report_and_quit (m_libcassert.c:415)
==11673==    by 0x3800D127: vgPlain_assert_fail (m_libcassert.c:481)
==11673==    by 0x38004A03: sg_instrument_IRStmt (sg_main.c:2332)
==11673==    by 0x380003B3: h_instrument (h_main.c:683)
==11673==    by 0x3802968D: tool_instrument_then_gdbserver_if_needed (m_translate.c:238)
==11673==    by 0x380D3290: LibVEX_Translate (main_main.c:934)
==11673==    by 0x380271BF: vgPlain_translate (m_translate.c:1765)
==11673==    by 0x3805F857: vgPlain_scheduler (scheduler.c:1048)
==11673==    by 0x38090445: run_a_thread_NORETURN (syswrap-linux.c:102)

sched status:
  running_tid=1

Thread 1: status = VgTs_Runnable (lwpid 11673)
==11673==    at 0x40169EA: _dl_runtime_resolve_xsave (in /usr/lib64/ld-2.17.so)
==11673==    by 0x1B: ???
==11673==    by 0x40057F: ??? (in /PATH/peihung/test/run)
==11673==    by 0xFFEFFF517: ???


Note: see also the FAQ in the source distribution.
It contains workarounds to several common problems.
In particular, if Valgrind aborted or crashed after
identifying problems in your program, there's a good chance
that fixing those problems will prevent Valgrind aborting or
crashing, especially if it happened in m_mallocfree.c.

My machine environment is Centos7 and x86_64




Thanks.
Best regards,
Pahome

Re: [Valgrind-users] new error message from Valgrind

[Mark W. <ma...@kl...>]

Hi,

On Wed, Aug 03, 2022 at 05:32:56PM +0100, Tom Hughes wrote:
> No, it's clone3:
> 
> https://bugs.kde.org/show_bug.cgi?id=420906

So please upgrade to valgrind 3.18.0 or higher (latest is 3.19.0).

Cheers,

Mark

Re: [Valgrind-users] new error message from Valgrind

[Mark R. <ma...@cs...>]

Just tried running the Valgrind test suite on WSL2 (win 10, Ubuntu 22.04).
I'm not surprised that there were lots of failures.  But the majority were:
WARNING: unhandled amd64-linux syscall: 435

I suspect WSL is not a platform you care much about, but looking at syswrap
for Darwin I see this might be pid hibernate?  Would it be difficult to add
support for this?

Thank you,
Mark

-----Original Message-----
From: Mark Wielaard [mailto:ma...@kl...]
Sent: Monday, August 1, 2022 4:56 AM
To: Tom Hughes <to...@co...>; Mark Roberts <ma...@cs...>;
val...@li...
Subject: Re: [Valgrind-users] new error message from Valgrind

On Thu, 2022-07-28 at 22:22 +0100, Tom Hughes via Valgrind-users wrote:
> On 28/07/2022 21:39, Mark Roberts wrote:
> > I recently upgraded from Ubutu 20.04 to 22.04 and am now getting a
> > new error message from Valgrind:
> >
> > --915-- WARNING: unhandled amd64-linux syscall: 334
> >
> > --915-- You may be able to write your own handler.
> >
> > --915-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
> >
> > --915-- Nevertheless we consider this a bug.  Please report
> >
> > --915-- it at http://valgrind.org/support/bug_reports.html
> > <http://valgrind.org/support/bug_reports.html>.
> >
> > Using same version of Valgrind as before (3.17).
> >
> > Any ideas as to what’s happening?
>
> Yes, your libc has started trying to use rseq.
>
> It's harmless - the next version of valgrind will silently reject it
> with ENOSYS which is what is happening now anyway just with a warning.

Where the next version of valgrind is 3.19.0 which is already released (in
April).  So you might just want to upgrade your valgrind.

If you want to backport to older versions then the commit that got rid of
the warning was:

commit 1024237358f01009fe233cb1294f3b8211304eaa
Author: Mark Wielaard <ma...@kl...>
Date:   Fri Dec 10 17:41:59 2021 +0100

    Implement linux rseq syscall as ENOSYS

    This implements rseq for amd64, arm, arm64, ppc32, ppc64,
    s390x and x86 linux as ENOSYS (without warning).

    glibc will start using rseq to accelerate sched_getcpu, if
    available. This would cause a warning from valgrind every
    time a new thread is started.

    Real rseq (restartable sequences) support is pretty hard, so
    for now just explicitly return ENOSYS (just like we do for clone3).


https://sourceware.org/pipermail/libc-alpha/2021-December/133656.html

Cheers,

Mark