On Tue 14-12-21 12:57:48, Andrew Morton wrote:
On Tue, 14 Dec 2021 11:11:54 +0100 Michal Hocko mhocko@suse.com wrote:
I need some clarification here. It sounds like memoryless nodes work on x86, but hotplug + memoryless nodes isn't a supported use case or you're introducing it as a new use case?
If this is a new use case, then I'm inclined to say this patch should NOT go in and a proper fix should be implemented on hotplug's side. I don't want to be in the business of having/seeing this conversation reoccur because we just papered over this issue in percpu.
The patch still seems to be in the mmotm tree. I have sent a different fix candidate [1] which should be more robust and cover also other potential places.
[1] http://lkml.kernel.org/r/20211214100732.26335-1-mhocko@kernel.org
Is cool, I'm paying attention.
We do want something short and simple for backporting to -stable (like Alexey's patch) so please bear that in mind while preparing an alternative.
I think we want something that fixes the underlying problem. Please keep in mind that the pcp allocation is not the only place to hit the issue. We have more. I do not want we want to handle each and every one separately.
I am definitly not going to push for my solution but if there is a consensus this is the right approach then I do not think we really want to implement these partial workarounds.