linux-kernel - Re: Repeated fork() causes SLAB to grow without bound

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Message-ID: <CANN689FiU87Vju7zTJ2yZNkw2aDd=K05fRKhoRGTn6Dp8btjLg@mail.gmail.com>
Date:	Mon, 20 Aug 2012 12:11:43 -0700
From:	Michel Lespinasse <walken@...gle.com>
To:	Rik van Riel <riel@...hat.com>
Cc:	Hugh Dickins <hughd@...gle.com>,
	Daniel Forrest <dan.forrest@...c.wisc.edu>,
	Andrea Arcangeli <aarcange@...hat.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: Repeated fork() causes SLAB to grow without bound

On Mon, Aug 20, 2012 at 4:53 AM, Michel Lespinasse <walken@...gle.com> wrote:
> I wonder if it might help to add the child VMA onto the parent's
> anon_vma only at the first child COW event. That way it would at least
> be possible (with userspace changes) for any forking servers to
> separate the areas they want to write into from the parent (such as
> things that need expensive initialization), from the ones that they
> want to write into from the child, and have none of the anon_vma lists
> grow too large.

Actually that wouldn't work. The parent's anon pages are visible from
the child, so the child vma needs to be on the parent anon_vma list.
Sorry for the noise :/

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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