Re: [PATCH mm-unstable] mm/demotion: Assign correct memory type for multiple dax devices with the same node affinity

[Andrew Morton]

On Fri, 26 Aug 2022 15:32:24 +0530 "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> wrote:

> With multiple dax devices having the same node affinity, the kernel wrongly assigned
> default_dram memory type to some devices after the memory hotplug operation. Fix this by
> not clearing node_memory_types on the dax device remove.
> 
> The current kernel cleared node_memory_type on successful removal of a dax device.
> But then we can have multiple dax devices with the same node affinity. Clearing the
> node_memory_type results in assigning other dax devices to the default dram type when
> we bring them online.

Thanks, I added this as a fix against "mm/demotion/dax/kmem: set node's
abstract distance to MEMTIER_DEFAULT_DAX_ADISTANCE".

Reworked this patch to apply, reworked all the subsequent patches as
a result of applying that, checked that this patch as-sent cleanly reverts
when all are applied, checked that everything compiled at each step of
the resulting series.