Re: Core dumps for threads

[Alan Cox]

> Can anyone explain why this test is in routine `do_coredump'
> in file `fs/exec.c' in the 2.4.0 kernel?
> 
>     if (!current->dumpable || atomic_read(&current->mm->mm_users) != 1)
> 	goto fail;
> 
> The only thing the test on `mm_users' seems to be doing is stopping
> a thread process from dumping core.  What's the rationale for this?

The I/O to dump the core would race other changes on the mm. The right fix
is probably to copy the mm (as fork does) then dump the copy.