Re: [15/17] SLUB: Support virtual fallback via SLAB_VFALLBACK

From: Peter Zijlstra
Date: Sat Sep 29 2007 - 04:58:51 EST



On Sat, 2007-09-29 at 10:47 +0200, Peter Zijlstra wrote:

> Ah, right, that was the detail... all this lumpy reclaim is useless for
> atomic allocations. And with SLUB using higher order pages, atomic !0
> order allocations will be very very common.
>
> One I can remember was:
>
> add_to_page_cache()
> radix_tree_insert()
> radix_tree_node_alloc()
> kmem_cache_alloc()
>
> which is an atomic callsite.
>
> Which leaves us in a situation where we can load pages, because there is
> free memory, but can't manage to allocate memory to track them..

Ah, I found a boot log of one of these sessions, its also full of
order-2 OOMs.. :-/

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