you must be very concerned about it too.
If you don't have the fallback prevention all your efforts around the
allocations targeted directoy zone normal will be completely worthless.
Either that or you want to drop ZONE_NORMAL enterely because it means
nothing uses zone-normal dynamically anymore (ZONE_NORMAL seen as a
place that is directly mapped, not necessairly always 32bit dma
capable).
> 64GB isn't getting any testing that I know of; I'd hold off until
> someone's actually stood up and confessed to attempting to boot
> Linux on such a beast. Or until I get some more RAM. =)
64GB is an example, a good example for this thing, but a 16G machine or
a 4G machine can run in the very same issues. As said just swapoff -a
and malloc(1G) and such 1G is all ZONE_NORMAL before you could allocate
enough inodes for your workload. Or alloc 1G of pagetables by setting
everything protnone, and sugh 1G of pagetables goes in zone-normal
because the highmem is filled by cache. Choose whatever is your
preferred example of real life bug fixed by the lowmem-reservation patch
that is absolutely necessary to run stable on a big box with normal zone
and highmem (not only a 64G box).
The only place where you must not be concerned about these fixes are the
64bit archs.
Andrea
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