Hi, some related work caused me to look at how we use get/put_mems_online() and get/put_online_cpus() during kmem cache creation/descruction/shrinking, and realize that it should be actually safe to remove all of that with rather small effort (as e.g. Michal Hocko suspected in some of the past discussions already). This has the benefit to avoid rather heavy locks that have caused locking order issues already in the past. So this is the result, Patches 1 and 2 remove memory hotplug and cpu hotplug locking, respectively. Patch 3 is due to realization that in fact some races exist despite the locks (even if not removed), but the most sane solution is not to introduce more of them, but rather accept some wasted memory in scenarios that should be rare anyway (full memory hot remove), as we do the same in other contexts already. It's all RFC for now, as I might have missed some reason why it's not safe. Vlastimil Babka (3): mm, slab, slub: stop taking memory hotplug lock mm, slab, slub: stop taking cpu hotplug lock mm, slub: stop freeing kmem_cache_node structures on node offline mm/slab_common.c | 20 ++++-------------- mm/slub.c | 54 ++++++++++++++++++++++++++++++++---------------- 2 files changed, 40 insertions(+), 34 deletions(-) -- 2.29.2
