Re: [PATCH] sched/numa, mm: do not promote folios to nodes not set N_MEMORY

[Oscar Salvador]

On Wed, Feb 14, 2024 at 12:53:55PM +0900, Byungchul Park wrote:
> While running qemu with a configuration where some CPUs don't have their
> local memory and with a kernel numa balancing on, the following oops has
> been observed. It's because of null pointers of ->zone_pgdat of zones of
> those nodes that are not initialized at booting time. So should avoid
> nodes not set N_MEMORY from getting promoted.

Looking at free_area_init(), we call free_area_init_node() for each node
found on the system.
And free_area_init_node()->free_area_init_core() inits all zones
belonging to the system via zone_init_internals().
Now, I am not saying the check is wrong because we obviously do not want
migrate memory to a memoryless node, but I am confused as to where
we are crashing.


-- 
Oscar Salvador
SUSE Labs