Re: [Feature Request?] Inline compression of process core dumps

[Randy Dunlap]

On Thu, 12 Apr 2007 22:22:18 -0400 Christopher S. Aker wrote:

> Alan Cox wrote:
>  > Indeed. So useful that in current kernels you can set the core dump
>  > path to be
>  >
>  >    "|application"
> 
> Cool stuff!  However, it's not working (2.6.20.6):
> 
>       Core dump to |/home/caker/bin/dumper.pl.4442 pipe failed
> 
> even though...
> 
>       # cat /proc/sys/kernel/core_uses_pid
>       0
>       # cat /proc/sys/kernel/core_pattern
>       |/home/caker/bin/dumper.pl
> 
> Looking at the code, it seems to me that format_corename() is appending 
> .pid, regardless if !core_uses_pid and corename[0]=='|', in which case 
> it creates an invalid path for call_usermodehelper_pipe().
> 
> Bug in the code, or bug in my methods?

What are you trying to dump?  is it a multi-thread group app,
not a "simple" app?  I ask because of this (I'm looking at 2.6.21-rc6)
<mm_users> reference (not that I know what that is):

        if (!pid_in_pattern
            && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
                rc = snprintf(out_ptr, out_end - out_ptr,
                              ".%d", current->tgid);
                if (rc > out_end - out_ptr)
                        goto out;
                out_ptr += rc;
        }

---
~Randy
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