Re: dwarf_loader.c: Fixed leaked bogon

[Rakesh Pandit <rakesh.pandit-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Finally had a look at this case again and I am able to reproduce it.
Kernel kills the command:
[rakesh@simu build]$ ./pfunct -l -P
~/testrpms/webkitgtk-debuginfo-1.1.12-1.fc12.x86_64/usr/lib/debug/usr/lib64/libwebkit-1.0.so.2.debug
with message:
May 10 12:19:20 simu kernel: Out of memory: kill process 2956 (bash)
score 496818 or a child
May 10 12:19:20 simu kernel: Killed process 5758 (pfunct)

On 6 January 2010 22:14, Arnaldo Carvalho de Melo  wrote:
> Em Wed, Jan 06, 2010 at 08:54:59PM +0530, Rakesh Pandit escreveu:
>> While checking one of big shared objects I found kernel getting
>> unhappy and sending SIGKILL. File was 282M libwebkit-1.0.so.2.8.1 from
>> webkit project. (Can be obtained from
>> http://kojipkgs.fedoraproject.org/packages/webkitgtk/1.1.12/2.fc12/x86_64/webkitgtk-debuginfo-1.1.12-2.fc12.x86_64.rpm
>> and extracted via rpm2cpio, file is libwebkit-1.0.so.2.8.1.debug)
>>
>> URL: http://rakesh.fedorapeople.org/misc/0001-dwarf_loader.c-Fixed-leaked-bogon.patch
>
> What is the exact command line you are using? You cannot destroy that
> obstack if you really will use the extra debugging info that is has
> many pointers that will point to some other info if you destroy it.
>
> By default cu->extra_dbg_info is false, it only is true if set
> explicitely by one of the tools, like:
>
> [acme@doppio pahole]$ grep extra_dbg_info *.c
> dwarf_loader.c: if (cu->extra_dbg_info) {
> dwarf_loader.c: return cu->extra_dbg_info ?
> dwarf_loader.c: return cu->extra_dbg_info ? dtag->decl_line : 0;
> dwarf_loader.c: return cu->extra_dbg_info ? dtag->id : 0;
> dwarf_loader.c: return cu->extra_dbg_info ? dtag->type : 0;
> dwarf_loader.c:         cu->extra_dbg_info = conf ? conf->extra_dbg_info : 0;
> dwarf_loader.c:         if (!cu->extra_dbg_info)
> dwarves.c:              self->extra_dbg_info = 0;
> pahole.c:                 conf_load.extra_dbg_info = 1;         break;
> pahole.c:                 conf_load.extra_dbg_info = 1;         break;
> pahole.c:                 conf_load.extra_dbg_info = 1;         break;
> pfunct.c:                 conf_load.extra_dbg_info = true;
> pfunct.c:                 conf_load.extra_dbg_info = 1;          break;
> pfunct.c:                 conf_load.extra_dbg_info = true;
> [acme@doppio pahole]$
>
> pahole and pfunct, and inpahole, assuming it is the one you are using:
>
>                .name = "decl_exclude",
>                .key  = 'D',
>                .arg  = "PREFIX",
>                .doc  = "exclude classes declared in files with PREFIX",
>
>        case 'D': decl_exclude_prefix = arg;
>                  decl_exclude_prefix_len = strlen(decl_exclude_prefix);
>                  conf_load.extra_dbg_info = 1;         break;
>
>                .name = "show_decl_info",
>                .key  = 'I',
>                .doc  = "Show the file and line number where the tags were defined"
>
>        case 'I': conf.show_decl_info = 1;
>                  conf_load.extra_dbg_info = 1;         break;
>
>                .name = "packable",
>                .key  = 'P',
>                .doc  = "show only structs that has holes that can be packed",
>
>        case 'P': show_packable = 1;
>                  conf_load.extra_dbg_info = 1;         break;
>
>
> The only seemingly "strange" case above is --packable, that I bet is
> what you're using, where it needs the extra debug info because for
> anonymous structs it shows in which file and line the struct is, and
> that is only available from the DWARF info.
>

I am using -l ( along with -P & one more option also) among the above.
ELF file is webkitgtk-debuginfo-1.1.12-1.fc12.x86_64/usr/lib/debug/usr/lib64/libwebkit-1.0.so.2.debug
which is essentially a symlink to libwebkit-1.0.so.2.8.1.debug in same
debuginfo rpm.

Link to debuginfo rpm is:
http://kojipkgs.fedoraproject.org/packages/webkitgtk/1.1.12/1.fc12/x86_64/webkitgtk-debuginfo-1.1.12-1.fc12.x86_64.rpm

It is 290 MB ELF file.

> Can you try the following patch to see if the problem goes away? We may
> want to just enable extra_dbg_info in this case if used with --verbose,
> something like that.
>

Looking into where this leaks happens and what would be better way to
deal with it.

-- 
Rakesh Pandit
https://fedoraproject.org/wiki/User:Rakesh
freedom, friends, features, first
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