Re: [RFC][PATCH 0/9] Network receive deadlock prevention for NBD
From: Peter Zijlstra
Date: Sat Aug 12 2006 - 07:45:59 EST
On Sat, 2006-08-12 at 14:42 +0400, Evgeniy Polyakov wrote:
> When network uses the same allocator, it depends on it, and thus it is
> possible to have (cut by you) a situation when reserve (which depends on
> SLAB and it's OOM too) is not filled or even does not exist.
No, the reserve does not depend on SLAB, and I totally short-circuit the
SLAB allocator for skbs and related on memory pressure.
The memalloc reserve is on the page allocator level and is only
accessable for PF_MEMALLOC processes or __GFP_MEMALLOC (new in my
patches) allocations. (arguably there could be some more deadlocks wrt.
PF_MEMALLOC where the code under PF_MEMALLOC is not properly bounded,
those would be bugs and should be fixed if present/found)
> If transferred to your implementation, then just steal some pages from
> SLAB when new network device is added and use them when OOM happens.
> It is much simpler and can help in the most of situations.
SLAB reclaim is painfull and has been tried by the time you OOM.
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