Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr

From: Tejun Heo
Date: Thu Jan 03 2019 - 13:47:14 EST


On Wed, Jan 02, 2019 at 07:05:38PM +0200, Mike Rapoport wrote:
> I agree that currently the bottom-up allocation after the kernel text has
> issues with KASLR. But this issues are not necessarily related to the
> memory hotplug. Even with a single memory node, a bottom-up allocation will
> fail if KASLR would put the kernel near the end of node0.
> What I am trying to understand is whether there is a fundamental reason to
> prevent allocations from [0, kernel_start)?
> Maybe Tejun can recall why he suggested to start bottom-up allocations from
> kernel_end.

That's from 79442ed189ac ("mm/memblock.c: introduce bottom-up
allocation mode"). I wasn't involved in that patch, so no idea why
the restrictions were added, but FWIW it doesn't seem necessary to me.