Re: [Patch] shm cleanups

[Ingo Molnar <mingo@chiara.csoma.elte.hu>]

On 4 Nov 1999, Christoph Rohland wrote:

> I do get swapping also with 8GB of RAM, but it runs out of memory
> before running out of swap space since prepare_highmem_swapout is
> failing way to often.
> 
> (It then locks up since it cannot free the shm segments and so is
> unable to free the memory. This should be perhaps addressed later in
> the oom handler. It cannot handle the case where nearly all memory is
> allocted in shm segments)

ho humm. I think prepare_highmem_swapout() has a design bug. It's way too
naive in low memory situations, it should keep a short list of pages for
emergency swapout. It's the GFP_ATOMIC that is failing too often, right?

i believe we should have some explicit mechanizm that tells vmscan that
there is 'IO in progress which will result in more memory', to distinct
between true out-of-memory and 'wait a little bit to get more RAM' cases?
I think we'd have a lot less to worry about and there would be a much
clearer distinction between true out-of-mem and 'just cannot allocate it
right now but help is on the way' cases.

	Ingo

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