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

[Rik van Riel]

On 08/20/2012 05:39 AM, Michel Lespinasse wrote:

> I would still prefer if we could just remove the anon_vma_chain stuff, though.

If only we could.

That simply replaces a medium issue at fork time, with the
potential for a catastrophic issue at page reclaim time,
in any workload with heavily forking server software.

Without the anon_vma_chains, we end up scanning every single
one of the child processes (and the parent) for every COWed
page, which can be a real issue when the VM runs into 1000
such pages, for 1000 child processes.

Unfortunately, we have seen this happen...

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