Re: [PATCH] powerpc/pseries: Track LMB nid instead of using device tree

Nathan Fontenot [off-list ref] writes:

On 09/19/2018 11:38 PM, Michael Ellerman wrote:

quoted

Nathan Fontenot [off-list ref] writes:

quoted

When removing memory we need to remove the memory from the node
it was added to instead of looking up the node it should be in
in the device tree.

During testing we have seen scenarios where the affinity for a
LMB changes due to a partition migration or PRRN event. In these
cases the node the LMB exists in may not match the node the device
tree indicates it belongs in. This can lead to a system crash
when trying to DLAPR remove the LMB after a migration or PRRN
event. The current code looks up the node in the device tree to
remove the LMB from, the crash occurs when we try to offline this
node and it does not have any data, i.e. node_data[nid] == NULL.

This isn't building for 32-bit etc:

arch/powerpc/mm/drmem.c: In function 'init_drmem_v1_lmbs':
arch/powerpc/mm/drmem.c:371:14: error: implicit declaration of function 'memory_add_physaddr_to_nid' [-Werror=implicit-function-declaration]
   lmb->nid = memory_add_physaddr_to_nid(lmb->base_addr);
              ^
cc1: all warnings being treated as errors
scripts/Makefile.build:317: recipe for target 'arch/powerpc/mm/drmem.o' failed

See the failed checks here:
  https://patchwork.ozlabs.org/patch/969150/


Probably drmem.c should only be compiled for 64-bit NUMA etc.

Looks like the root cause is that memory hotplug relies on sparsemem which
is not supported on 32-bit.

Yeah that could be it.

Making drmem.c built just for MEMORY_HOTPLUG would make sense.

This patch is also going to need a refresh to apply cleanly due to other
patches that have gone in. I'll re-submit after looking at the build break issues more.

OK thanks.

cheers