[arch-general] valgrind - memory exclusion files on the fritz?

[Chi-Hsuan Yen]

On Thu, Nov 24, 2016 at 8:45 AM, David C. Rankin
<drankinatty at suddenlinkmail.com> wrote:
> On 11/23/2016 08:49 AM, Chi-Hsuan Yen via arch-general wrote:
>> As far as I know it's impossible (yet) to skip specific functions in
>> memory usage counters. Only memory leak reports can be filtered. And
>> things may be different on SuSE and Arch as they ship with different
>> glibc versions and/or patches.
>>
>> Best,
>>
>> Yen, Chi-Hsuan
>
> I have a couple of old arch boxes I cranked up just to test:
>
> $ uname -a
> Linux providence 3.5.3-1-ARCH #1 SMP PREEMPT Sun Aug 26 08:15:06 UTC 2012 i686
> GNU/Linux
>
> $ valgrind ./bin/valgrindchk
> ==7060== Memcheck, a memory error detector
> ==7060== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
> ==7060== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
> ==7060== Command: ./bin/valgrindchk
> ==7060==
>  s : 0123456789
> ==7060==
> ==7060== HEAP SUMMARY:
> ==7060==     in use at exit: 0 bytes in 0 blocks
> ==7060==   total heap usage: 1 allocs, 1 frees, 11 bytes allocated
> ==7060==
> ==7060== All heap blocks were freed -- no leaks are possible
> ==7060==
> ==7060== For counts of detected and suppressed errors, rerun with: -v
> ==7060== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
>
> and a second old arch box:
>
> $ uname -a
> Linux nirvana 3.4.6-1-ARCH #1 SMP PREEMPT Fri Jul 20 08:21:26 CEST 2012 x86_64
> GNU/Linux
>
> $ valgrind ./bin/valgrindchk
> ==3481== Memcheck, a memory error detector
> ==3481== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
> ==3481== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
> ==3481== Command: ./bin/valgrindchk
> ==3481==
>  s : 0123456789
> ==3481==
> ==3481== HEAP SUMMARY:
> ==3481==     in use at exit: 0 bytes in 0 blocks
> ==3481==   total heap usage: 1 allocs, 1 frees, 11 bytes allocated
> ==3481==
> ==3481== All heap blocks were freed -- no leaks are possible
> ==3481==
> ==3481== For counts of detected and suppressed errors, rerun with: -v
> ==3481== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 1 from 1)
>
>   Both boxes show the correct valgrind behavior. So sometime (I don't know
> when), something has changed in the way valgrind is packaged or patched. I
> have some old ABS backups I'll take a look at and see if anything is apparent.
>
>   The whole reason this jumped out at me is I know this used to work correctly
> on Arch which incorporated the proper exclusion files up to at least valgrind
> 3.10-0 as shown above.
>
> --
> David C. Rankin, J.D.,P.E.

OK I found the cause of the extra malloc() call. Since glibc 2.23
printf uses malloc instead of mmap to allocate file buffers. If you
want to keep the old behavior, keep the old glibc.

See https://sourceware.org/bugzilla/show_bug.cgi?id=16734

Best,

Yen, Chi-Hsuan