[PATCH] Core dumps for threads

From: Don Dugger (ddugger@willie.n0ano.com)
Date: Tue Feb 27 2001 - 12:29:54 EST

OK, I followed Alan's suggestion and here is a patch, relative to
the 2.4.1 kernel, that copies the mm and dumps the corefile from
that copy. Also, whenever there are multiple users of the original
mm it creates the core dump in the file `core.n' where `n' is the
PID of the offending process.

I would contend that this fixes a bug and should be put into the
2.4 but if the concensus is that it's a new 2.5 feature that's fine.

On Sat, Feb 24, 2001 at 09:57:44PM +0000, Alan Cox wrote:
> > 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.
>
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-- 
Don Dugger
"Censeo Toto nos in Kansa esse decisse." - D. Gale
n0ano@valinux.com
Ph: 303/938-9838
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