Re: [Intel-IOMMU 02/10] Library routine for pre-allocat pool handling

[Christoph Lameter]

On Sat, 9 Jun 2007, Andi Kleen wrote:

> > Why was it not allowed? Because interrupts are disabled?
> 
> Allocating memory during page out under low memory could 
> lead to deadlocks. That is because Linux used to make no attempt
> to limit dirty pages for anonymous mappings and then you could
> end up with most of your memory dirty and not enough 
> memory cleanable for page out and then when page out 
> needs more memory you could be dead.
> 
> [yes that implies that mmap over NFS was always broken]

Right. We got that fixed in 2.6.19.

> Now there is a anon dirty limit since a few releases, but I'm not
> fully convinced it solves the problem completely.

A gut feeling or is there more?

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