Re: [PATCH] mm: limit lowmem_reserve

[Nick Piggin <nickpiggin@yahoo.com.au>]

Con Kolivas wrote:
> On Saturday 08 April 2006 10:55, Nick Piggin wrote:
>
> > Con Kolivas wrote:
> >
> > > On Friday 07 April 2006 22:40, Nick Piggin wrote:
> > >
> > > > How would zone_watermark_ok always fail though?
> > >
> > > Withdrew this patch a while back; ignore
> >
> > Well, whether or not that particular patch isa good idea, it
> > is definitely a bug if zone_watermark_ok could ever always
> > fail due to lowmem reserve and we should fix it.
>
>
> Ok. I think I presented enough information for why I thought zone_watermark_ok 
> would fail (for ZONE_DMA). With 16MB ZONE_DMA and a vmsplit of 3GB we have a 
> lowmem_reserve of 12MB. It's pretty hard to keep that much ZONE_DMA free, I 
> don't think I've ever seen that much free on my ZONE_DMA on an ordinary 
> desktop without any particular ZONE_DMA users. Changing the tunable can make 
> the lowmem_reserve larger than ZONE_DMA is on any vmsplit too as far as I 
> understand the ratio.

Umm, for ZONE_DMA allocations, ZONE_DMA isn't a lower zone. So that
12MB protection should never come into it (unless it is buggy?).

--
SUSE Labs, Novell Inc.
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