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Subject: Re: [PATCH] Core dumps for threads
To: ddugger@willie.n0ano.com (Don Dugger)
Date: Tue, 27 Feb 2001 17:55:45 +0000 (GMT)
Cc: torvalds@transmeta.com (Linus Torvalds), linux-kernel@vger.kernel.org,
        alan@lxorguk.ukuu.org.uk (Alan Cox)
In-Reply-To: <20010227102954.A26230@willie.n0ano.com> from "Don Dugger" at Feb 27, 2001 10:29:54 AM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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> 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.

> +	if ((mm = kmem_cache_alloc(mm_cachep, SLAB_KERNEL)) == NULL)
> +		goto close_fail;
> +	memcpy(mm, current->mm, sizeof(*mm));
> +	if (!mm_init(mm)) {
> +		kmem_cache_free(mm_cachep, mm);
> +		goto close_fail;
> +	}
> +	down(&current->mm->mmap_sem);

Umm not quite what I meant. Take a look at copy_mm in fork.c

The code starting

	m = allocate_mm()

down to just before

	/*
  	 * child gets a 

Does the real thing you need to do to be sure the mm is properly set up.
You can also drop the original mm and make that current->mm to avoid the
passing of mm around. In fact you probably should do that.