Re: [RFC PATCH 2/2] mm/vmscan.c: Prevent allocating shrinker_info on offlined nodes

On 12/6/21 05:45, David Hildenbrand wrote:

quoted

This doesn't seen complete. Slab shrinkers are used in the reclaim
context. Previously offline nodes could be onlined later and this would
lead to NULL ptr because there is no hook to allocate new shrinker
infos. This would be also really impractical because this would have to
update all existing memcgs...

Instead of going through the trouble of updating...

...  maybe just keep for_each_node() and check if the target node is
offline. If it's offline, just allocate from the first online node.
After all, we're not using __GFP_THISNODE, so there are no guarantees
either way ...

Thanks for your reviews David :)

Yes, I believe this would be a viable solution. At this point it looks like our
short term solution would be something along this line. Long term we would want
to either allocate all pgdats (which will waste memory) or update the memcgs
with the appropriate node information once a node is onlined. Im currently
working a solution that does the latter.