Re: [discuss] mmap, mbind and write to mmap'ed memory crashes 2.6.16-rc1[2] on 2 node X86_64

From: Andi Kleen
Date: Wed Feb 08 2006 - 11:05:46 EST

On Wednesday 08 February 2006 16:59, Christoph Lameter wrote:
> On Wed, 8 Feb 2006, Andi Kleen wrote:
> > On Wednesday 08 February 2006 16:42, Christoph Lameter wrote:
> >
> > > However, this has implications for policy_zone. This variable should store
> > > the zone that policies apply to. However, in your case this zone will vary
> > > which may lead to all sorts of weird behavior even if we fix
> > > bind_zonelist. To which zone does policy apply? ZONE_NORMAL or ZONE_DMA32?
> >
> > It really needs to apply to both (currently you can't police 4GB of your
> > memory on x86-64) But I haven't worked out a good design how to implement it yet.
> So a provisional solution would be to simply ignore empty zones in
> bind_zonelist?

That would likely prevent the crash yes (Bharata can you test?)

But of course it still has the problem of a lot of memory being unpolicied
on machines with >4GB if there's both DMA32 and NORMAL.

> Or fall back to earlier zones (which includes unpolicied
> zones in the bind zone list?)

Or that.


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